Content uploaded by Naveed Shah
Author content
All content in this area was uploaded by Naveed Shah on Apr 17, 2024
Content may be subject to copyright.
Journal Pre-proof
The Critical Impacts of Cytokine Storms in Respiratory Disorders
Shahana Riyaz Tramboo, Ahmed M.E. Elkhalifa, Syed Quibtiya, Sofi Imtiyaz Ali,
Naveed Nazir Shah, Syed Taifa, Rabia Rakhshan, Iqra Hussain Shah, Muzafar
Ahmad Mir, Masood Malik, Zahid Ramzan, Nusrat Bashir, Shubeena Ahad, Ibraq
Khursheed, Elsharif.A. Bazie, Elsadig Mohamed Ahmed, Abozer Y. Elderdery, Fawaz
O. Alenazy, Awad Alanazi, Badr Alzahrani, Muharib Alruwaili, Emad Manni, Sana
Elfatih, Ezeldine K. Abdalhabib, Showkat Ul Nabi
PII: S2405-8440(24)05800-6
DOI: https://doi.org/10.1016/j.heliyon.2024.e29769
Reference: HLY 29769
To appear in: HELIYON
Received Date: 16 January 2024
Revised Date: 15 April 2024
Accepted Date: 15 April 2024
Please cite this article as: The Critical Impacts of Cytokine Storms in Respiratory Disorders, HELIYON,
https://doi.org/10.1016/j.heliyon.2024.e29769.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition
of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of
record. This version will undergo additional copyediting, typesetting and review before it is published
in its final form, but we are providing this version to give early visibility of the article. Please note that,
during the production process, errors may be discovered which could affect the content, and all legal
disclaimers that apply to the journal pertain.
© 2024 Published by Elsevier Ltd.
The Critical Impacts of Cytokine Storms in Respiratory Disorders
Shahana Riyaz Tramboo1, Ahmed M. E. Elkhalifa 2, 3*, Syed Quibtiya4, Sofi Imtiyaz Ali1,
Naveed Nazir Shah5, Syed Taifa1, Rabia Rakhshan6, Iqra Hussain Shah1, Muzafar Ahmad Mir1,
Masood Malik1, Zahid Ramzan1, Nusrat Bashir1, Shubeena Ahad1, Ibraq Khursheed7, Elsharif.
A. Bazie8, Elsadig Mohamed Ahmed9,10, Abozer Y. Elderdery11*, Fawaz O. Alenazy11, Awad
Alanazi11, Badr Alzahrani11, Muharib Alruwaili11, Emad Manni11, Sana Elfatih11, Ezeldine K
Abdalhabib11, Showkat Ul Nabi1*
1Preclinical Research Laboratory, Department of Clinical Veterinary Medicine, Ethics &
Jurisprudence, Sher-e-Kashmir University of Agricultural Sciences and Technology
(SKUAST-Kashmir), Srinagar, J&K-190006, India.
2Department of Public Health, College of Health Sciences, Saudi Electronic University, Riyadh
11673, Saudi Arabia.
3Department of Haematology, Faculty of Medical Laboratory Sciences, University of El Imam
El Mahdi, Kosti 1158, Sudan.
4Department of General Surgery, Sher-I-Kashmir Institute of Medical Sciences, Medical
College, Srinagar-190011, Jammu & Kashmir, India.
5Department of Chest Medicine, Govt. Medical College, Srinagar-191202, Jammu & Kashmir,
India.
6Department of Clinical Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir -
190006, India
7Department of Zoology, Central University of Kashmir, 191201 Nunar, Ganderbal, Jammu &
Kashmir, India
8Pediatric Department, Faculty of Medicine; University of El Imam El Mahdi, Kosti 1158,
Sudan.
9Department of Medical Laboratory Sciences, College of Applied Medical Sciences,
University of Bisha, Bisha 61922, Saudi Arabia
10Department of Clinical Chemistry, Faculty of Medical Laboratory Sciences, University of El
Imam El Mahdi, Kosti 1158, Sudan.
11Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf
University, Sakaka, Saudi Arabia.
Journal Pre-proof
*Correspondence at:
First Corresponding Author
Showkat Ul Nabi
Preclinical Research Laboratory, Department of Clinical Veterinary Medicine, Ethics &
Jurisprudence, Sher-e-Kashmir University of Agricultural Sciences and Technology
(SKUAST-Kashmir), Srinagar J&K-190006, India. Email: showkatnabi@skuastkashmir.ac.in
Second Corresponding Author
Ahmed M. E. Elkhalifa
Department of Public Health, College of Health Sciences, Saudi Electronic University, Riyadh
11673, Saudi Arabia.
Department of Haematology, Faculty of Medical Laboratory Sciences, University of El Imam
El Mahdi, Kosti 1158, Sudan Email: a.alkhalifa@seu.edu.sa
Third Corresponding Author
Abozer Y. Elderdery
Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf
University, Sakaka, Saudi Arabia. Email: ayelderdery@ju.edu.sa
Journal Pre-proof
Abstract
Cytokine storm (CS) refers to the spontaneous dysregulated and hyper-activated
inflammatory reaction occurring in various clinical conditions, ranging from microbial
infection to end-stage organ failure. Recently the novel coronavirus involved in COVID-19
(Coronavirus disease-19) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome
Coronavirus 2) has been associated with the pathological phenomenon of CS in critically ill
patients. Furthermore, critically ill patients suffering from CS are likely to have a grave
prognosis and a higher case fatality rate. Pathologically CS is manifested as hyper-immune
activation and is clinically manifested as multiple organ failure. An in-depth understanding
of the etiology of CS will enable the discovery of not just disease risk factors of CS but also
therapeutic approaches to modulate the immune response and improve outcomes in patients
with respiratory diseases having CS in the pathogenic pathway. Owing to the grave
consequences of CS in various diseases, this phenomenon has attracted the attention of
researchers and clinicians throughout the globe. So in the present manuscript, we have
attempted to discuss CS and its ramifications in COVID-19 and other respiratory diseases,
as well as prospective treatment approaches and biomarkers of the cytokine storm.
Furthermore, we have attempted to provide in-depth insight into CS from both a
prophylactic and therapeutic point of view. In addition, we have included recent findings of
CS in respiratory diseases reported from different parts of the world, which are based on
expert opinion, clinical case-control research, experimental research, and a case-controlled
cohort approach.
Keywords: Cytokine storm, SARS-CoV-2, Respiratory diseases, biomarkers, and immune
response.
Journal Pre-proof
1. Introduction
Cytokine storm refers to a dysregulated and excessive immune response characterized by
the release of a large number of pro-inflammatory cytokines into the bloodstream. This
phenomenon can have severe consequences and is associated with various medical
conditions, including viral infections, autoimmune diseases, and certain therapies [1,2]. The
COVID-19 epidemic has underlined the significance of a robust host immune system and
deleterious consequences observed in immunological dysregulation [1,2]. Throughout the
body, a variety of cells release tiny glycoproteins called cytokines that have a variety of
functions prominent among them including cell proliferation, cellular differentiation,
autocrine, paracrine, and/or endocrine functions, as well as influencing immune and
inflammatory responses [3]. The abnormal release of cytokines in response to infection or
stimulation, also known as hypercytokinemia, can result in life-threatening immune
dysregulation [4]. Such systemic inflammatory disorders are characterized by an elevated
number of circulating cytokines, and hyper-activation of immune-cells, all of which cause
multiple organ failure if not treated properly and the pathological condition has been referred
to as cytokine storm (CS) [5]. The phrase "cytokine storm" was coined by [6] during a
medical literature discussion on graft versus host disease. The perplexing etiology of
COVID-19 is marked by significantly enhanced cytokine production which results both in
considerable mortality and grave disease progression [6] The increased case fatality of the
recent SARS-CoV-2 pandemic is attributed to uncontrolled and dysregulated cytokine
production which results from severe Acute Respiratory Distress Syndrome (ARDS)
symptoms, which further causes significantly higher mortality rate in these patients [7].
Studies across the globe have reported that activation of immune cells by various viruses
that infect the pulmonary system promotes secretion of a diverse set of cytokines which
enhances endothelial-vascular permeability and allows blood cells and fluid to migrate into
the alveoli henceforth causing dyspnea and respiratory failure [7-12]. In addition to SARS-
CoV-2 viruses that induce CS include SARS-CoV-1, H1N1 influenza, H5N1 influenza,
Ebola infections, and Influenza Band Parainfluenza virus, [13]. Similarly, non-infectious
diseases, such as Graft-versus-host disease (GvHD) can also result in CS [14]. These viruses
cause the release of numerous cytokines and chemokines after infecting epithelial cells of
the lungs which stimulate alveolar macrophages. Recently, studies have found that the
release of viral nucleic acids causes sensitization/activation of immune cells [15]. CS storm
has been observed in a wide spectrum of diseases and different authors have reported the
Journal Pre-proof
alteration in biochemical and clinical presentation of disease (Table 1). Owing to the
catastrophic outcomes associated with CS, there is an urgent need to have an in-depth
understanding CS, henceforth the study aims to provide insights (i) to provide an
understanding about potential risk/etiological factors responsible for initiation of CS in wide
spectrum of respiratory diseases. (ii) Critical impact of CS on initiation, progression and
outcomes of respiratory disorders (iii) Evaluate the specific cytokines involved CS and their
potential to serve as surrogate and endpoint biomarkers for disease severity and prognosis.
(iv) potential therapeutic regimens available for targeting CS to mitigate inflammation and
improve patient outcomes in respiratory disorders. (v) Enhance understanding of the
interplay between cytokine storms and other pathological processes.
2. Methodology
For drafting the present review, we searched Medline, Pubmed, Elsevier, clinicaltrail.gov.in,
and Google Scholar with the words COVID-19, cytokine storm, clinical trials, and a
combination of these words. We followed the referred reporting in reviews and meta-analysis,
furthermore, for the present study we searched for a database from the World Health
Organization clinical trials registry (WHO) for the collection of data we used the technique of
snowballing to include only relevant studies in the present study. Search design was followed
to include all the published papers on COVID-19-associated CS. A total of 2398 papers were
found to deal with COVID-19, out of these 1753 papers were irrelevant for drafting present
review articles and they were excluded. From the remaining 645 papers, 456 were found to
deal with COVID-19 only and in these papers, there was nothing relevant regarding cytokine
storm so they were also excluded, from the remaining 189 papers we drafted in the current
review article.
2.1 Inclusion/Exclusion Criteria
2.1.1 Inclusion Criteria
i. The present study incorporated case studies/series, meta-analyses/systemic reviews,
observational studies (retrospective/prospective), and clinical trials (randomized/non-
randomized) that featured confirmed diagnoses of CS and respiratory disorders.
ii. Clinical cases with a confirmatory diagnosis of respiratory disorder and concurrently
showing pathognomonic features of CS.
iii. Published Studies/records dealing with the respiratory disorder and concurrent incidence
of CS.
Journal Pre-proof
2.1.2 Exclusion Criteria
i. From the current study, we excluded studies where the confirmatory diagnosis of either
the respiratory disorder or CS was not reported, and clinical and biochemical presentation
was not documented.
ii. Studies where standard diagnostic protocol/procedures were not adopted for diagnostic
criteria established for respiratory disorder and CS.
iii. Unpublished data, thesis, preprints, and studies published in language other than English
language were excluded from the drafting of the current manuscript.
iv. Editorial comments, Newspaper writing, personal suggestions, and incomplete data were
excluded from the current study.
3. Clinical features and clinical abnormalities of CS in pulmonary diseases
Cytokines play vital role in progression, and outcome of the pulmonary diseases. After the
disease's degenerative processes begin, clinical symptoms become more complicated and
complex in manifestation [11]. Because of the simultaneous manifestation of hyper
inflammation, hemostasis disruption, and reduced platelet counts, CS may result in a
significant risk of spontaneous bleeding [1]. A range of illnesses, including kidney failure,
acute hepatitis, and stress-related cardiomyopathy can result in advanced stages of CS [12]
(Figure 1). Similarly, renal failure can cause leaky capillary syndrome which mimics the
changes found in cancer patients undergoing therapeutic intervention using high-dose
interleukin-2 [13]. The cytokine storm's neurotoxic consequences are usually delayed,
taking several days to manifest; these findings are in concurrence with the neurologic side
effects of T-cell immunotherapy known as immune effector cell-associated neurotoxicity
syndrome [14]. Clinical manifestation in CS differs because of the underlying causes and
severity as indicated by nonspecific inflammatory indicators such as C-reactive protein
(CRP) [15]. High triglyceride levels, as well as thrombocytopenia, leukopenia, leukocytosis,
anemia, elevated acute phase proteins, and other blood-count abnormalities, are considered
biochemical mediators which cause dysregulation of immune cum inflammatory pathways
which henceforth results in positive feedback for progression of CS [16]. Serum levels of
interferons, chemokines, interferon-γ, and other pro-inflammatory markers’ as well as T-
cell activation factors are all elevated in CS. In CS induced by therapeutic CAR T-cell
therapy, serum IL-6 levels were observed to be significantly elevated [17] [18]. Furthermore,
the levels of IL-6 were observed to be elevated in individuals affected by SARS and other
diseases experiencing severe manifestations of the illness [19].
Journal Pre-proof
4. Pathophysiological characteristics of pulmonary CS
In respiratory illnesses, cytokine storm generates a variety of functional alterations which
are manifested as clinical signs of the cytokine storm. Cytokines have systemic effects and
can harm important organ systems at certain high levels henceforth rendering them
potentially harmful [20]. Excessive production of cytokines might harm vital organs,
potentially outweighing the benefits of an immune response [1]. Regulatory cells, as well as
decoy receptors for pro-inflammatory cytokines like IL1RA and anti-inflammatory
cytokines like IL-10, suppress inflammatory cell populations; henceforth limiting cytokine-
induced immune hyper-activation [1]. Hyper-immune activation occurs occasionally as a
consequence of dysregulation or increased amplitude of the immune system, to exemplify
CAR T-cell therapy, primary hemophagocytic lymph histiocytosis (HLH) [21]. In each of
these conditions, feedback mechanisms that would otherwise stop hyper-inflammation are
rendered ineffective which results in overproduction of inflammatory cytokines. Owing to
the emergence of COVID-19-associated cytokine storm researchers have had an opportunity
to distinguish COVID-19 CS and other forms of CS, COVID-19 associated CS involves the
release of the wide spectrum of pro-inflammatory cytokines both in quantity and quality
compared to other forms of CS [22], henceforth in COVID-19 CS, there is aggressive
manifestation of disease spectrum. Lymphopenia is less frequently encountered in other
forms of CS compared to COVID-19 CS where lymphopenia constitutes the characteristic
finding [23]. Furthermore, compared to other bacterial CS the therapeutic interventions
required in COVID-19 CS are more aggressive and need to be more precise in targeting
potential targets of the CS. Although the pathogenic pathway involved in COVID-19 CS
has not been established based on the analogy drawn from earlier outbreaks like MERS-
CoV, it can be postulated that viral entry through ACE-2 receptor and release of the RNA
and other components of RNA like double-stranded RNA and PAMPs (pathogen-associated
molecule pattern (PAMP) interact with pattern recognition receptors (PRRs) of host cells
which results in over expression of pro-inflammatory cytokines, especially IFN-1 [24]. The
hyper-inflammatory response impairs viral clearance and causes a cascade of reactions
which further results in the production of more pro-inflammatory cytokines by activation of
local pulmonary innate response [25]. These pro-inflammatory cytokines attract more
inflammatory cells and immune cells, hence causing activation of adaptive immune response
with the recruitment of CD4+ and CD8+ T cells, which results in persistent inflammatory
response that activates emergency granulopoiesis, macrophage activation, and erythro-
Journal Pre-proof
phagocytosis which damages pulmonary tissue architecture. Erythro-phagocytosis results
in anemia, capillary leakage, and activation of the intrinsic pathway of coagulation which
results in the formation of emboli in the blood vascular system [26]. Furthermore, in CS
natural regulatory systems like Tregs which produce IL-10 and TNF-β are down-regulated
by excessive production of pro-inflammatory cytokines. Based on these findings’
researchers have proposed that in COVID-19 CS an unfortunate event of uncontrolled
immune response culminates in a hyper-inflammatory response [15].
5. Criteria for diagnosis and recognition of CS
The criteria for recognition and diagnosis of CS constitute an important topic of discussion
among researchers and the healthcare community. Various clinical, biochemical, and
radiographic abnormalities are peculiar to CS patients and some of them are pathognomonic
for diagnosis of CS [6, 11] (Table 2 and 3).
5. 1. Radiological findings as criteria for CS diagnosis
Although radiological abnormalities observed in patients with pulmonary form of cytokine
storm require further standardization and verification in COVID-19 patients concurrently
affected with cytokine storm demonstrate gross and microscopic findings which typically
represent a hyper-inflammatory state [27]. The most common findings observed in these
patients include ground-glass opacities which may be especially in subpleural, peripheral,
and bilateral in presentation [28], significantly increased width of pleura [29], ill-defined
margin of the pulmonary architecture [30], alveolar consolidation [31] and interlobular
thickening [32]. The increase production of IL-1β induces the production of pulmonary
exudates which imparts ground glass appearance to lung parenchyma. The cytokine storm
operates in chronological order within the pulmonary tissue; up to 3 days of initiation of
cytokine storm lung parenchyma appears almost normal, and from the 3-9th day ground glass
appearance of pulmonary tissue becomes evident [33, 34]. During the later stage of the
cytokine storm interlobular thickening occurs and a fibrous strip develops inside the lung
parenchyma [35].
5. 2 Biochemical alterations as criteria for CS diagnosis
In recent case series, some of the biochemical alterations have been observed in patients
with CS [28]. It has been observed that patients with CS have a higher incidence of
hypercoagulability which subsequently results in vascular thrombosis mostly observed in
Journal Pre-proof
younger age groups of patients [36]. Among the various biochemical markers considered D-
dimer levels of >1.5 µg/mL had high sensitivity and specificity in the prediction of
hypercoagulability [37]. Concurrently, patients with a serum D-dimer level greater than 1
µg/mL were found to have higher mortality rates compared to those with a serum D-dimer
level below this threshold [38]. Similarly, Pulmonary thromboembolism (PE) has been
reported by Computed Tomography pulmonary angiogram (CTPA) in patients with high D-
dimer levels [38, 9]. Furthermore, in these patients prothrombin time was reported to be
>3.0 s with prolonged aPTT >5 which indirectly indicates thrombotic complications
suggestive of bleeding risk owing to consumption of coagulation factors [39]. Postmortem
examination of patients with CS revealed small blood vessels of pulmonary tissue being
occluded with platelets and small thrombi which consequently resulted in diffuse pulmonary
damage [40]. Owing to the higher incidence of pulmonary thromboembolism in patients
with CS, the hypothesis of hypercoagulability in CS merits further investigation. Recently
large cohort study (n=449) was conducted in CS patients and they found a significant
correlation between higher levels of D-dimer and prothrombin time with mortality rate [41].
So, they proposed D-dimer and prothrombin time can serve as early biomarkers of the
cytokine storm progression. However, they refuted the use of platelet count and aPTT as
markers of the cytokine storm as they could not observe any significant difference between
CS patients and the healthy class of patients [42]. These propositions are further supported
by recently conducted meta-analysis considering 9 studies and they reported unanimously
elevated levels of D-dimer in critically ill patients compared to patients group moderately
ill [43]. Other cellular determinant of cytokine storm recognized include significant
neutrophilia which has been reported to cause cellular damage to the tissue architecture and
causes necrosis of the tissues. Earlier studies conducted in Wuhan have reported significant
elevation in neutrophil count in non-survivors compared to patients that survived,
furthermore, a steady increase in mature and immature neutrophil levels was observed till
the death of these patients [11]. Another study utilized a multi-omics approach and found
that markers of neutrophil (Neutrophil Elastase and Myeloperoxidase) were significantly
elevated in critically ill patients with cytokine storm compared to healthy counterparts [44].
Another study conducted by [45] found increased levels of pyruvate kinase M2 (PKM2) an
indicator of hypoxia in critically ill patients with cytokine storm compared to patients with
mild degree of illness. Furthermore, an immune-metabolomics study found that cytokine
storms cause programming and proliferation of neutrophils [46]. These findings are further
supported by the characteristic clinical presentation of cytokine storm which includes
Journal Pre-proof
elevation in an array of cytokines including interleukins (IL) (IL-1, IL-2, IL-6, IL-7, IL-8,
IL-10, IL-12, IL-17, and IL-18) [47]. In addition to this, lymphopenia has been observed in
CS, indicating that cytokine storm is triggered by innate rather than adaptive immune cells
[47].
5.3 Clinical presentation as criteria for CS diagnosis
The duration of the CS can be predicted by the etiology of the disorders and their therapeutic
interventions used to treat the disease [1]. Almost all patients with CS and respiratory
illnesses experience high fever, tiredness, loss of appetite, headache, rash, diarrhea, joint
pain, muscle pain, and mental symptoms [48] (Figure 1). These symptoms could be caused
by acute physiological changes, cytokine-induced tissue damage, or immunological
reactions mediated by immune cells [49]. They can cause disseminated intravascular
coagulation, hypoxemia, hypotension, dyspnea, hemostasis imbalance, and vasodilatory
shock henceforth may necessitate invasive ventilation in respiratory diseases [50].
Although detailed guidelines for understanding the above-mentioned changes are yet to be
established, henceforth designing a scoring system like that of the Penn grading scale, MS
scoring and HS scoring which are established scoring systems developed for the
characterization of adverse events may provide some benefit in prediction of COVID-19 CS
[51]. In this direction [51], proposed criteria for the characterization of COVID-19 CS based
on three cluster models which include (i). Albumin level less than 2.87 mg/mL, lymphocyte
count less than 10.2 %, and neutrophil count more than 11.4 × 103/mL. (ii). ALT level more
than 60 IU/L, AST level more than 87 IU/L, D-Dimer levels more than 4930 ng/mL, LDH
levels more than 416 U/Land troponin I level more than1.09 ng/mL. (iii). Anion gap less
than 6.8 mmol/L, levels of sodium, potassium, and urea above the reference range values,
and ferritin levels more than 250 ng/mL. On similar lines [52, 53] proposed revised criteria
for diagnosis of CS, which included a fraction of oxygen saturation to a fraction of inspired
oxygen levels (SPO2/FiO2), significantly higher levels of ferritin, C-reactive protein, and D-
Dimer. Recently [13] proposed the use of HS scoring in combination with biochemical assay
for diagnosis of COVID-19 CS. Despite the need for validation and precision, these studies
provide baseline criteria for designing officially accepted guidelines for the fabrication of
diagnostic criteria for COVID-19 CS.
6. Cell types and signaling pathways involved in pulmonary cytokine storm
Journal Pre-proof
Inflammatory cell types such as lymphocytes, reticuloendothelial cells, and NK cells are all
involved in the pathophysiology of CS in respiratory diseases. Neutrophils help to generate
thrombi, whereas macrophages derived from circulating monocytes have several functions,
including ingestion of foreign materials and initiating an immune response. In a cytokine
storm, different immune cells secrete different cytokines, for instance, T cells and NK cells,
release IFN-γ, which stimulates macrophages and causes clinical symptoms characteristic
of CS [54]. The cytokines released from activated immune cells trigger a cascade of immune
signaling pathways causing CS during respiratory diseases. Excessive cytokine release is
induced by macrophages, which can result in tissue damage and organ failure in some cases.
In patients with lung infections, CS has been found to have hemophagocytic macrophages
in their bone marrow. Interferon-γ (IFN-γ) causes macrophage-induced hemophagocytosis,
which may contribute to the cytopenia found in CS patients [55-57]. NK cells cause
cytolysis, which is decreased in some types of cytokine storm, resulting in prolonged
stimulation of antigenic determinants and ineffective resolution of inflammation [58]. In
addition to this by reducing perforin and granzyme synthesis by IL-6, NK-cell function is
reduced. Hence excessive Th1-type inflammatory responses result in considerable levels of
interferon-delayed hypersensitivity reactions and macrophage activation, both of which are
required for intracellular infection defense. COVID-19 CS is a dynamic process that
involves hyper activation of inflammatory processes and the activation of various signaling
pathways. In the subsequent section, we will discuss the related pathways involved in
COVID-19 CS (Figures 2 and 3).
6.1. IL-6/JAK/STAT signaling pathway
The signaling pathway was proposed based on the predominant finding of elevated IL-6
levels observed in critically ill COVID-19 patients [59]. Increased levels of IL-6 cause
activation of trans and cis signaling of JAK/STAT, which is supposed to have a pleiotropic
effect on immune cell activation, reduced synthesis of Tregs, and enhanced recruitment of
immune cells and differentiation of CD4+ and CD8+ T cells [60]. This results in the vicious
circle of further production of pro-inflammatory cytokines and acute phase proteins which
results in hyper-inflammatory response and organ failure [61].
6.2. IFN-γ/JAK/STAT signaling
IFN- γ is the main activator and driver of immune cell proliferation and exerts protection
against viral and bacterial infections through up-regulation of JAK1/JAK2 and down-
Journal Pre-proof
regulation of STAT1-IFN-γ-activated site (GAS) cascades [62]. There is a plethora of
studies that postulate hyper-activation of immune and inflammatory pathways but it is not
clearly defined how IFN- γ is involved in CS. However, based on its role in immune
activation it can be well postulated that IFN- γ has a significant role in CS. Of special
interest, some studies have found significantly decreased levels of IFN- γ produced byCD4+
T cells in patients with severe manifestation of disease compared to patients with mild
manifestation of disease; these findings have been attributed to functional exhaustion of
CD4+ T cells [63]. So, it has been postulated that elevated levels of IFN- γ occurs from
macrophages and not from CD4+ T cells [64].
6.3. TNFα/NF-κB signaling
TNFα is one of the most important pro-inflammatory cytokines produced by immune cells
on their activation [65]. For the production of TNFα and other pro-inflammatory cytokines,
NF-κB plays a pivotal role via activation of pro-inflammatory and anti-apoptotic genes [66].
Henceforth, TNFα/NF-κB interplay causes initiation of CS which subsequently causes
apoptosis of the epithelial cells and results in epithelial-immune cell interplay to fuel
inflammatory processes [67]. Contrary to this hypothesis, a clinical trial conducted in
Wuhan China found significantly reduced levels of TNFα in critically ill patients compared
to moderately ill patients [68] and subsequent studies reported levels of TNFα within the
normal range in different patients’ classes across the severity of disease [69]. Hence there is
an urgent need for further research to understand the role of TNFα in CS, although recent
research suggests that inhibition of the TNFα/NF-κB signaling pathway causes
improvement in critically ill COVID-19 patients [70].
6.4. NLRP3/IL-1β signaling
An important pro-inflammatory cytokine secreted by macrophages causes migration of
immune cells to the infected site, production of various adhesive factors, and has positive
feedback on activation of NF-κB and results in auto-activation for production of more IL-
1β quantity [71]. It has been proposed that excessive ROS (Reactive Oxygen Species)
production causes activation of NLRP3 which results in cleavage of inactive IL-1β precursor
into an active form of IL-1β, hence initiating a vicious circle of cytokine storm [72]. Owing
to the increased incidence of cytokine storm in COVID-19 patients there have been
significant improvements and enhancements in research on cytokine storm-associated
Journal Pre-proof
COVID-19 and various signaling pathways have been proposed. These pathways are
indicated in Table 3.
7. Cytokines involved in pulmonary CS
Among the cytokines involved in the CS, the most prominent are recombinant cytokines and
interferon [73-75]. Key cytokines of CS include INF-γ, IL-1, IL-6, TNF, and IL-18, which
are assumed to serve crucial immunopathology activities [76]. IL-1, IL-6, and TNF-α
produce fever, which is a clinical characteristic of cytokine storm. IL-6, a critical modulator
of the acute inflammatory response and a CS pathophysiological characteristic is greatly
increased in a variety of immunopathology illnesses [13, 77-78). Among the various pro-
inflammatory cytokines, the following pro-inflammatory cytokines deserve special mention
(Table 3).
7.1. IL-6
IL-6 is one of the pivotal cytokines because it is produced by numerous organ systems and
has effects on both immune and non-immune cells. The cis- and trans-signaling routes are
the two main signaling pathways [79] involved in the production of IL-6. Membrane-bound
gp130 is found throughout the body, but membrane-bound IL-6 Receptors are found mostly
in reticuloendothelial cells. The pleiotropic consequences of cis signaling activation on the
immune system cause CS [79]. TNF-α is a multifunctional inflammatory cytokine that
produces fever, increases systemic inflammation, activates antimicrobial responses like IL-
6, and regulates immunity and cell death. It is classified under the TNF–TNF receptor
superfamily. TNF activates NFk-B, which stimulates many genes involved in inflammatory
response.
7.2. IL-18
Furthermore, in addition to these mediators, IL-18 has also been linked to CS [80]. The
alternate pathway involves pathogenic microorganisms and sterile stressors, which are
detected by inflammasomes, which are multi-molecular cytosolic sensors. Caspase-1 is
activated during pyroptosis, which then activates IL-18 and IL-1 from their progenitors [81,
82]. Recently some of the studies have found that IL-18 activatesTh1-type responses by
stimulating the release of INF-γ from immune cells. It produces Th1-type inflammatory
responses in synergism with IL-12 and IL-15. In individuals with CS-induced immune cell
stimulation syndrome, blood concentrations of IL-18 are high [83-85].IL–18–binding
Journal Pre-proof
protein (IL18BP) controls the pro-inflammatory effects of IL-18 and aids in the prevention
of IL-18 and receptor binding [81, 86].
7.3. IL-10
To decrease systemic off-target effects, regulatory cytokines like IL-10 and naturally
occurring pro-inflammatory cytokine antagonists like IL1RA are used as immune
modulators. TNF, IL-1, IL-6, and IL-12 are all inhibited by IL-10, as well as antigen
presentation is also inhibited by IL-10 [87].
7.4. Complement proteins
Plasma proteins like complement proteins and some less understood proteins act as
promoters to cause CS by providing feedback on cytokine signaling, detecting infections,
and enhancing cellular responses. The production of complement proteins is increased by
cytokines, which maintains the feedback mechanism by increasing or lowering cytokine
production. Complement, although its high efficacy at killing microorganisms, can
occasionally cause collateral damage if created in excess. To support these propositions
Hypocomplementemia has also been discovered in situations of CS caused by the
overconsumption of immune complexes [88]. A significantly positive correlation was found
between levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and
complement factors (C3a, C5a, and factor P (properdin) in critically ill COVID-19 patients
with associated CS compared to moderately ill patients, henceforth these findings reflect the
potential utility of complement factors to serve as biomarkers of severity of disease
progression in COVID-19 associated CS [13].
8. Types of pulmonary cytokine storm
8.1. Iatrogenic cytokine storm
Infusion of engineered CAR T cells into CD19+ lymphoma patients triggers a CS by boosting
IFN-γ and IL-6 levels [88- 90]. Pre-clinical studies have found that macrophages play a pivotal
role in the progression of CS by releasing cytokines and promoting immune dysfunction and
these immune dysregulations can be effectively reversed by IL-1 [91]. Similarly, iatrogenic CS
has been observed as a result of tumor lysis produced by the introduction of pyroptosis in target
tumor cells [92]. Immunotherapy which activates T cells by binding to both CD19+ and CD3+
T cells results in iatrogenic CS and the pathological cascade has been successfully inhibited by
using anti-IL-6 antibody therapy, which further affirms the role of IL-6 [71]. T-cell stimulation
Journal Pre-proof
triggers iatrogenic cytokine storm, which is propagated by immune cell activation. CD28
receptor is a secondary receptor located on the T cell membrane after the primary receptor of
T Cell Receptor (TCR), these two receptors play pivotal roles in the activation of T cells, which
include T cell differentiation and T cell remodeling and immune modulation and immune
regulation. Studies have found that infusion of ant-CD28 (TGN1412) results in an immune
imbalance which triggers hyper-activation of immune cum inflammatory response and
culminates into CS. [93]. This is because of the simultaneous stimulation of diverse sets of
immune cells [94]. Although CAR T cells or Blinatumomab contribute to the cytokine storm,
this is not necessarily the case in all patients due to other factors which include genetic
background of patients, dose of the drug, and time of introduction/initiation of therapy[95, 96].
Other iatrogenic causes of CS include drugs obtained from biological organisms like Rituximab
[70], gene therapies, immune system hotspot inhibitors, organ transplant surgeries [97], and
allogeneic stem-cell transplantation, in addition to these bioterrorism agents like
Staphylococcal enterotoxin B and Francisella tularensis also cause iatrogenic CS [70].
8.2. Pathogen-induced pulmonary cytokine storm
Despite the paucity of evidence, investigations have demonstrated that pathogen-induced
pulmonary CS can be caused by a diverse set of pathogenic micro-organisms [98, 99]. Sepsis
in microbial infections can result in fever, cell death, coagulopathies, and multi-organ failure
due to cytokine production [100, 103] (Table 1). Excess cytokine production can cause more
harm than infection, therefore it can have a more detrimental impact [104].
8.2.1. Bacterial infections
Super-antigens produced by bacteria such as Streptococcus species and Staphylococcus
aureus bind with the MHC and T-cell receptors, resulting in T-cell stimulation and
concurrent release of cytokines which culminate into toxic shock syndrome [105]. These
super antigens are strong T-cell mitogens, capable of causing fever, shock, and death at
doses as low as 0.1pg/ml [96].
8.2.2. Viral infections
It has been found that widespread viral infections can also set off cytokine storms. A high
inflammatory response against infectious agents has been shown to alter pathogen detection,
effectors, regulatory systems, and hyper-activation of inflammation [55, 106]. Furthermore,
studies have reported multi-centric Castleman's disease (HHV-8) caused by Kaposi's
Journal Pre-proof
sarcoma herpesvirus as an important disease that involves CS in its pathogenesis [107].
From cell line studies it has been found that HHV-8 infected cells produce significantly
higher levels of interleukin-6 which results in a CS [108, 109]. By similar pathways viruses
such as herpes simplex virus and influenza viruses such as H5N1 can also induce CS [110].
8.3. Monogenic or autoimmune cytokine storm
This type of CS is caused due to impairments in recessive autosomal genes. For instance, in
patients with primary HLH granule-mediated cytotoxicity has been attributed to recessive
mutation in autosomal genes [111]. In addition to this, patients with secondary HLH,
experience CS as a result of a variety of pathogenic, immune-mediated, or metaplastic
disorders, and mutations in the selected genes [112, 113]. In HLH, the levels of cytokines
are elevated [111]. In some HLH patients, the beneficial effects of immune-suppressants,
anti-neoplastic drugs, anti-inflammatory antibodies, pro-inflammatory antagonists, IL-6
antagonists, and anti-inflammatory drugs point that the pathogenic hotspots targeted by
these medications have a significant role in the progression of auto-immune pulmonary CS
[114]. Humans affected with this disorder have structural changes in genes influencing the
immune system and inflammasome stimulation [115]. Such patients experience unprovoked
release of cytokines and initiation of CS without signs of infection. Based on the studies that
have postulated genetic defects as possible risk factors for the pathogenesis of this disorder,
these studies have reported TNF-α, IL-1, and IL-18 as major drivers of cytokine storms in
these genetic diseases [106]. Chronic granulomatous disease and STAT1 gain-of-function
disease are two hereditary immunodeficiency illnesses that have been associated with CS
[116]. The CS was most severe and was manifested as thrombocytopenia, anasarca, fever,
reticulin fibrosis, and organomegaly (TAFRO) subtype [117]. In the wide spectrum of auto-
immune pulmonary CS instances, IL-6 was found to be the primary driver of pathogenesis,
while the rationale for this is unknown [118]. So recent studies have postulated that CS in
respiratory illnesses promotes pathologic changes via engaging macrophages and/or
monocytes [51]. These changes lead to hyper inflammatory response in respiratory diseases,
with the formation of free radicals which subsequently cause cell death [119]. Henceforth
the ROS (Reactive Oxygen Species) promotes the synthesis of NLRP3 and NF-kB, resulting
in an increase in cytokine production and, eventually, a CS [59]. Ultimately these patients
develop ARDS, sepsis, multiple organ dysfunctions, and as a result, eventually die of auto-
immune pulmonary CS [120].
Journal Pre-proof
9. Relationship between inflammatory cytokine levels and pulmonary disease
progression
A Plethora of preclinical and preclinical studies have investigated the casual relationship
between elevated inflammatory cytokine levels and the progression of pulmonary diseases,
with special emphasis on chronic respiratory conditions such as chronic obstructive
pulmonary disease (COPD) [121], asthma [122], acute respiratory distress syndrome
(ARDS) and interstitial lung diseases [123]. In these respiratory diseases, the role of
dysregulated cytokine responses in driving lung pathology has been identified as a
prominent pathology [124]. Recent investigations into the COVID-19 pandemic have
further emphasized the critical interplay between inflammatory cytokines and pulmonary
disease progression [125]. Understanding the dynamics of inflammatory cytokines in
pulmonary diseases is crucial for the development of targeted therapeutic interventions.
Interventions aimed at modulating cytokine levels, such as the use of anti-cytokine
antibodies or small molecule inhibitors, are areas of active research and may hold promise
for mitigating pulmonary disease progression [126].
So, researchers have investigated the molecular determinant activated by pathogens and they
have identified various cellular and subcellular moieties. Pathogens encounter a robust
immune response orchestrated by the host's defense mechanisms, a critical element in
combating infections [127]. Pattern recognition receptors (PRRs) on host cells play a pivotal
role in identifying a broad spectrum of cellular surface moieties on pathogens, termed
"pathogen-associated molecular patterns" (PAMPs). The interaction between PAMPs and
PRRs initiates an inflammatory cascade, triggering the activation of various products,
including genes encoding pro-inflammatory cytokines [54]. Key mediators, such as NF-kB,
activation protein 1, and interferon response factors 3 and 7, activated by PRRs, drive the
expression of potent inflammatory mediators [128]. Consequently, immune cells and
proteins migrate to the infection site, resisting the invading pathogens. Elevated cytokine
levels facilitate immune cell recruitment from the bloodstream, leading to the destabilization
of endothelial cell-cell connections, capillary endothelial damage, and eventual diffuse
alveolar damage [129]. Cytokine storm (CS) inflicts severe damage to pulmonary tissue,
potentially progressing to Acute Respiratory Distress Syndrome (ARDS), representing the
most devastating consequence of CS [130-132]. Immediate CS treatment is imperative to
prevent ARDS, as a lack of adequate medication may result in multiple organ dysfunctions
and fatalities. Recent findings, notably in the context of the COVID-19 pandemic,
underscore the respiratory infection's severe impact on various organs, particularly the
Journal Pre-proof
lungs. Post-mortem examinations of lung tissue in severely affected COVID-19 patients
reveal extensive alveolar edema, fibroblast infiltration, fibrin deposition, and lymphocytic
infiltration [62]. Critically ill COVID-19 patients exhibit significantly higher concentrations
of interleukins, TNF-α, and immune attractant proteins (protein 1 and protein 1A) compared
to mildly infected cases [133-135]. This underscores the importance of understanding and
addressing cytokine responses, highlighting potential therapeutic interventions to mitigate
the severity of respiratory infections and improve patient outcomes.
10. Clinical Course of cytokine storm
The clinical course of a cytokine storm typically involves distinct phases, ranging from
initiation to resolution or, in severe cases, progression to organ failure [23].
i. Initial phase: This phase is also called as prodromal phase, which is characterized
by the activation of immune cells in response to an event like a viral infection,
microbial infection, or other inflammatory stimuli [136]. As a result of the
production of multiple pro-inflammatory molecules, lung epithelial cells, pulmonary
parenchyma, and associated pulmonary micro-vascular architecture undergo
apoptosis, resulting in alveolar edema [137]. Chronic manifestation of CS results in
pulmonary fibrosis mediated by pro-inflammatory factors as well as chemokines and
reactive oxygen species [138].
ii. Amplification phase: This phase is characterized by excessive release of pro-
inflammatory cytokines (IL-6, TNF-α IL-1β) which contributes to the systemic
nature of the CS and can lead to widespread inflammation and tissue damage [139].
The CS can disrupt endothelial cell function, resulting in coagulation abnormalities,
micro vascular permeability alterations, hemorrhages, and thrombosis [140].
Furthermore, extravasations of solutes, fluid, macromolecules, and hormones, as
well as platelets and blood cells are facilitated by endothelial cells. In normal
circumstances, epithelial cells use a surface enzyme ecto-ATPase to break down
adenosine triphosphate (ATP) and adenosine diphosphate (ADP) in healthy people.
In CS and likewise conditions epithelial cell mal-function leads to abnormal ADP
production and platelet activation, which leads to thrombosis. This initiates a vicious
cycle whereby abnormally high concentration of ADP causes inactivation of surface
enzyme ecto-ATPase henceforth further inhibits hydrolysis of ATP and ADP
molecules [141].
Journal Pre-proof
iii. Organ Dysfunction Phase: This phase of CS leads to organ dysfunction and this
phase is often associated with life-threatening complications and requires intensive
medical intervention [142]. Overall, CS manifests clinically as "overlap syndrome"
marked by a significantly reduced cell count, reduction in ESR, elevated ferritin
level, NK dysfunction, and enhanced auto-hematophagy [143], which leads to
increased perivascular cupping of activated immune cells. Furthermore, this causes
recruitment of fibroblasts in pulmonary tissue which results in widespread fibrin
deposition which leads to alveolar collapse [144, 145].
iv. Resolution Phase: In some cases, CS may resolve spontaneously as anti-
inflammatory and immune modulatory mechanism comes into play. However, this
phase is highly dependent on the specific context and the underlying cause of the
cytokine storm
In the following section, we will be discussing the involvement of the CS in some of the
prominent viral respiratory pandemics in detail. Furthermore, their presentation is tabulated
in Table 1 and Table 2.
10.1. COVID-19
In recent studies conducted throughout the globe, circulating pro-inflammatory cytokine
levels were found to be positively correlated with the severity of diseases in COVID-19
[146]. These pro-inflammatory cytokines have been linked to the cause of mortality in
COVID-19-infected individuals [147]. For instance, CS in COVID-19 can be attributed to
the stimulation of immune receptors that are membrane-bound and which drive Th1 cells,
CD14+ and CD16+ monocytes 148]. The pathogenic Th1 lineage is swiftly stimulated by
SARS-CoV-2, causing the release of IL-6 and granulocyte-macrophage colony-stimulating
factor (GM-CSF) [149]. GM-CSF also causes inflammatory CD14+ and CD16+ monocytes
to become activated and production of IL-6 and TNF-α. Toll-like receptors (TLRs) and F
care types of membrane-bound immune receptors also contribute to dysregulated
inflammatory response, furthermore, insufficient IFN-induction can lead to increased
cytokine output [150]. Recently an important finding has been reported which postulates
that in COVID-19, cytokine release is triggered by extracellular traps of neutrophils [151].
CSIL-6 performs an important function by increasing vascular permeability which
henceforth results in interstitial edema induced by activation of the complement system (CS)
and allowing mast cells to release histamine [152]. Furthermore, the coagulation pathway is
Journal Pre-proof
activated by IL-6 which can lead to DIC (Disseminated Intravascular Coagulation) [153]. In
patients infected with COVID-19, recent research has attributed the grave prognosis of
disease to cytokine storms as well as other factors such as old age, corticosteroid medication,
and immune-competence [63].
10.2. MERS (Middle East respiratory syndrome)
MERS infection is associated with significantly enhanced levels of pro-inflammatory
cytokines [153-155]. Similarly, it was found that antiviral cytokines tend to decrease in
MERS while pro-inflammatory cytokines, particularly IL-6, increase in these individuals
[156]. The clinical manifestations of the disease which include deadly acute respiratory
failure, pulmonary fibrosis, and collapsing alveoli, are attributed to CS [157]. Several
mediators appear to be the most active mediators in the onset of extreme respiratory failures,
as these factors diffuse into tissue substratum and cause tissue damage [158]. Furthermore,
some chemokines and cytokines as well as induced protein 10 (IP10), MCP-1, IL-6, and IL-
1 were considerably enhanced in severe COVID-19, MERS, and SARS, according to recent
investigations [159-161].
10.3. H1N1 Influenza A
These viruses proliferate in pulmonary epithelial cells which create a “cytokine storm" of
inflammatory cytokines/chemokines, which is eventually activated by viral nonstructural
protein 1 (NS1) [162]. The pathophysiology and poor clinical outcomes are mostly caused
by uncontrolled replication of the virus which subsequently causes CS [163, 64]. When the
H2O2-MPO system is activated, the NS1 type of viral protein produced by the cells promotes
excessive production of MCP-1 by macrophages and IL-8 a chemokine by neutrophils
implying that the NS1viral protein of influenza virus H1N1 (PR-8) plays a key role in the
CS [57]. The CS induced by the influenza virus NS1 is considered a primary regulator and
it has been verified in animal models [165]. The CS does not appear to be caused solely by
the infiltration of macrophages and NK cells. The innate immune cells are driven to the lung
which intensifies the cytokine storm, increasing lung damage. The elevated concentrations
of cytokines, serum interferon, and other mediators of inflammation in individuals with
H1N1-induced pneumonia and ARDS are indicative of a CS [166].
11. Therapeutic options available
Journal Pre-proof
CS results in high death and grave prognosis henceforth early treatment of viral infections
like MERS and SARS [167], as well as the use of immune-modulators to control
inflammatory responses [168] has been shown to enhance the prognosis [169-173] (Figure
4; Figure 2; Table 4).
11.1. IFN-λ
IFN- λ has been employed to cure CS by activating epithelial cells, which reduces IFN-'s
pro-inflammatory effect mediated by mononuclear macrophages [162]. Additionally, it aids
in preventing neutrophils from being assigned to inflammatory areas [163]. The antiviral
genes are activated by IFN-λ in epithelial cells, resulting in antiviral actions without over
stimulation of the immune system [48]. Interferon lowers viral load efficiently when given
early and hence improves patients' clinical symptoms to some degree. Interferon, however,
has failed to control death rates [60] (Figure 4; Figure 2).
11.2. Corticosteroid therapies
Corticosteroids have anti-inflammatory properties and are widely used to reduce
inflammation [164]. Early benefits such as a decrease in fever, relief from lymphocytic
infiltration in pulmonary tissue [165], and improvement in oxygenation have been noted if
corticosteroids are administered appropriately and on time [165]. Corticosteroid-treated
SARS patients had lower death rates, and subsequent infections and associated problems
were uncommon in them [166]. However, investigations have demonstrated that giving
corticosteroids to human SARS-CoV patients has negative consequences. In lung infections
like COVID-19, corticosteroid therapy is still a challenge for clinicians [167], because
timely administration of corticosteroids and adequate dosage is critical. If glucocorticoids
are given too early, the body's immunological defense mechanism is hindered, which leads
to an increase in viral load and ultimately unfavorable effects. As a result, glucocorticoids
are used primarily in the treatment of critically ill patients who are experiencing an
inflammatory cytokine storm. Excessive inflammation is controlled in the early stages of an
inflammatory CS when glucocorticoids are given on time, which successfully prevents
ARDS and protects organ functions in patients. In patients with significantly reduced
oxygen saturation, deteriorated imaging, and an exaggerated inflammatory reaction,
glucocorticoid therapy within 3–5 days has been proven to be beneficial. However, because
of the immunosuppression caused by high dosages of glucocorticoids, the clearance of
coronavirus can be slowed [168-170] (Figure 2).
Journal Pre-proof
11.3. IL family antagonists
11.3.1. IL-1 antagonists
The important pro-inflammatory markers involved in CS are IL-1, IL-6, and IL-33 [171].
Studies that attempted to ameliorate CS by inhibiting IL-1 have received a lot of attention.
An IL-1 blocker, Anakinra, resulted in an improvement in the 28-day survival rate of
seriously ill COVID-19 individuals with extreme sepsis when treated for infection-induced
CS [56]. There is inadequate data that supports the use of specific IL-1 class antagonists for
the treatment of COVID-19, which requires additional verification in actual clinical settings
using randomized case-control clinical studies [172] (Figure 2 and Figure 4).
11.3.2. IL-6 antagonists
Tocilizumab, being an effective IL-6 antagonist has been used against autoimmune illnesses
as it helps in suppressing the immune system [173]. Furthermore, Tocilizumab is a drug that
is used to treat infection-induced cytokine storms [174]. In the case of pulmonary infections
like COVID-19, serum IL-6 levels were found to rise dramatically in seriously ill
individuals. Clinical trials of Tocilizumab in China recorded that it is highly efficient in
curing critically ill subjects with severe pulmonary lesions and increased IL-6 levels
[175,176].
11.4 Pro-inflammatory cytokine blockers
11.4.1. TNF-α blockers
TNFs are major inflammatory mediators and interesting targets for CS management. The
survival rates were considerably improved in patients with sepsis who received anti-TNF
medication as per [52] as well as effective in the treatment of non-infectious disorders such
as atherosclerosis [177].In animal models, TNFs have been associated with acute lung
injury, and TNFs have also been shown to block T cell response in humanized laboratory
animal models of SARS-CoV [178]. Mice were found to be protected from SARS-CoV-
related morbidity and mortality when TNF activity was neutralized or the TNF receptor was
deleted [179] (Figure 2 and Figure 4).
11.4.2. IFN-αβ inhibitors
IFN inhibits virus multiplication by activating the IFN-αβ stimulated gene. IFN-αβ, on the
other hand, has been found to exacerbate illnesses by increasing the stimulation of cells of
Journal Pre-proof
innate immunity and mononuclear macrophages [180]. Early interferon signaling has been
proven to be protective in humanized laboratory animal models of respiratory infection,
whereas chronic IFN signaling has been shown to cause an imbalance of anti-SARS-CoV
immune responses in humans [181]. To minimize excessive inflammatory reactions, these
antagonists should always be used in the early stages of serious illness [182].
11.5. Chloroquine
Chloroquine is an anti-malarial medication that was discovered in 1934 and is included in
the WHO’s Model List of Essential Medicines for 2019 [80]. Chloroquine inhibits the
production of pro-inflammatory cytokines, implying these mediators can ameliorate the CS
in clinical cases of pulmonary infections. Chloroquine phosphate has also been utilized in
China to treat adults aged 18 to 65 infected with COVID-19 [72].
11.6. Ulinastatin
Ulinastatin belongs to the category of natural anti-inflammatory drugs that shield the
vascular endothelium by preventing inflammatory mediators from being produced and
released [183]. It is used against pancreatitis and acute circulatory failure [184]. Ulinastatin
helps to reduce those cytokines that fuel the CS process (TNF, IL-6, and IFN-α) and
simultaneously enhances levels of that cytokine which dampens the inflammatory process
(IL-10). In humans, Ulinastatin maintains the equilibrium between these two classes of
cytokine responses by preventing CS hence regulating inflammation's chain reaction [185].
Several animal studies have shown that high-dose Ulinastatin has an anti-inflammatory
effect similar to glucocorticoid hormones. Ulinastatin, differs from glucocorticoids, as this
drug does not suppress immune response processes and is unlikely to induce side effects
most commonly found in glucocorticoid therapy, for instance, femoral head necrosis. These
drugs are frequently employed in the treatment regimen for COVID-19 individuals.
11.7 Oxidized phospholipids (OxPL) inhibitors
Oxidized phospholipids inhibitors were reported to ameliorate CS in humanized animal
models of respiratory infections by decreasing the release of cytokines/macrophages in
pulmonary tissue via the Toll-like receptor 4 (TLR4) and simultaneously causing induction
of INF-γ signaling pathway [186]. TLR4 antagonist Eritoran has high immune modulatory
properties but no direct antiviral action. Eritoran decreases the synthesis of OxPL,
inflammatory mediators in humanized animal models, resulting in a reduction in mortality
Journal Pre-proof
[187]. Human coronaviruses have been reported to generate enhanced OxPL production in
the lung tissues of patients, leading to ALI (Acute Lung Injury) [186]. The Eritoran and
other OxPL inhibitors, as a result, appear to be effective in reducing HCoV-induced
inflammation.
11.8 Sphingosine-1-phosphate receptor 1 (S1P1) agonist therapy
These drugs belong to the class of signal lysophospholipid that boosts the production and
secretion of cytokines [187]. The CS induced by influenza infection leading to tissue
damage as a consequence of adaptive as well as innate immune responses [57] is
dramatically reduced by the S1P receptor signaling pathways [188]. In a variety of
laboratory animal models of respiratory infections, S1P1 signaling in pulmonary tissue has
been demonstrated to have beneficial effects against inflammatory responses [57]. As a
result, S1P1 agonists act on pathogenic hotspots in the pathogenesis of pulmonary infections
and reduce mortality by preventing uncontrolled recruitment of mediators of inflammation
and chemokines [57, 188]. As SARS-CoV-2 primarily causes disease in epithelial and
endothelial cells of the human lung, antagonists of S1P1 may be viable therapeutic
medications to reduce inflammatory mediators in HCoV patients with triggered hyper-
immune response of cells [57]. Recently these classes of drugs were approved in 2019 to
treat multiple sclerosis. However, more research is needed under clinically controlled
randomized design to determine whether siponimod is a good substitute for CS therapy in
actual clinical settings.
11.9. Stem cell therapy
MSCs (Mesenchyme stem cells) are the type of progenitor cells that have powerful anti-
inflammatory and immunological regulatory properties in addition to the ability to self-
renew and multi-directionally differentiate ability [189]. MSCs promote the development of
regulatory T lymphocytes and macrophages, as well as the reduction of aberrant T
lymphocyte and macrophage recruitment and stimulation, and regulate the release of
mediators of inflammation, henceforth lowering the incidence of hyper-stimulation of the
inflammatory pathway [190]. MSC can also produce hepatocyte growth factor (HGF),
keratinocyte growth factor (KGF), VEGF, and IL-10, which can ameliorate ARDS, repair
lung tissue, and prevent fibrosis [191] (Figure 4).
11.10. Blood purification treatments
Journal Pre-proof
Ultra-blood purification procedures can eliminate inflammatory components from
circulatory blood to some extent. It involves exchange, adsorption, plasma perfusion,
blood/plasma filtration, and other procedures that remove inflammatory components and
obstruct the "cytokine storm" [192]. In the initial phase of the disease, blood purification
procedures can be used to help severely ill subjects. Academician Li Lanjuan's artificial liver
technology can remove inflammatory substances from the blood. Transfusion methodology
is being utilized to avert the H7N9 CS, and its deployment in COVID-19 indicates
encouraging results [65].
11.11. Targeting mononuclear macrophage
The regulation of C-C chemokine receptor type 2 (CCR2) by small interfering RNA
(siRNA) has been shown to diminish the transport of inflammatory cells to infection sites,
which has also been proven in animal studies [193, 194]. The pulmonary tissue of COVID-
19 patients had substantial infiltration of inflammatory cells, according to autopsy studies
[87]. When mononuclear macrophages come into contact with single-stranded RNA
(ssRNA) viruses, TLR7 agonists induce them to produce a powerful inflammatory response.
So using TLR7 antagonists appears to reduce the inflammatory CS caused by SARS-CoV-
2 infection. Recently researchers have proposed the strengthening of endothelial barrier as
a strategy to avert cytokine storm. Significantly enhanced vascular permeability is an
indicator of a modification in the cytokine storm's mechanism. It was discovered in animal
studies with sepsis where this strategy activated the endothelial Slit-Robo4 pathway and
hence significantly reduced vascular permeability, therefore decreasing infection-induced
cytokine storms [192].
12. Conclusion
Inflammation plays a pivotal role in robust immunity against any infection after the
infectious agent has been identified. When a foreign pathogen enters the body, immune cells
are activated, assisting in its eradication and restoring equilibrium. Infected persons with
pulmonary involvement experience CS, which results in deleterious effects caused by CS.
The use of immunomodulators and cytokine antagonists to control the CS early on, as well
as limiting inflammatory cell recruitment in the lungs, is crucial. This increases the efficacy
of CS treatment and reduces the number of people who die from the disease. There is an
urgent need to identify the mechanistic pathways involved in CS identification of potential
hotspots and effective targeting of these hotspots. Although a wide spectrum of medicinal
Journal Pre-proof
preparations have been proposed to be used against CS, these preparations need to be
evaluated in case-controlled randomized clinical trials, so that an effective and precisely
personalized therapeutic regimen can be developed against CS in general and pulmonary
determinants in particular.
Data availability statement
The data supporting this study's findings are available from the corresponding author upon
reasonable request.
Conflict of Interest
The author does not bear any conflict of interest.
Legends
Figure 1: Clinical manifestation of cytokine storm, cytokine storm involves multiple organ
failure mediated by hyper-activation of inflammatory pathways. The wide range of clinical
abnormalities observed in CS varies from patient to patient based on the severity of the
disease.
Figure 2: Various sub-cellular pathways involved in CS, these pathways are involved in the
promotion of hyper-transcription of inflammatory, pro-inflammatory, and other mediators
that fuel the CS.
Figure 3: Potential triggers of CS, positive and negative regulators involved in the
pathogenesis of CS, and description of effective blockers to ameliorate the progression of
CS.
Figure 4: Therapeutic options available for the treatment of cytokine storm in respiratory
disease with a special focus on targeting potential hotspots involved in the progression of
CS.
Table 1: Manifestation of cytokine storm in various infectious diseases with special
emphasis on diagnostic criteria for identification of CS.
Table 2: Diagnostic criteria proposed by researchers for early identification of CS in
COVID-19 patients.
Journal Pre-proof
Table 3: Role of various pro-inflammatory and inflammatory mediators in COVID-19-
associated CS.
Table 4: Therapeutic interventions for the treatment of cytokine storm in respiratory
disease.
References
1. Fajgenbaum, D.C. and June, C.H., 2020. Cytokine storm. NEJM. 383 (23), 2255-
2273.
2. Manik, M. and Singh, R.K., 2022. Role of toll‐like receptors in modulation of
cytokine storm signaling in SARS‐CoV‐2‐induced COVID‐19. J Med
Virol, 94(3), 869-877.
3. Kelleni, M.T., 2022. NSAIDs/nitazoxanide/azithromycin repurposed for COVID-
19: potential mitigation of the cytokine storm interleukin-6 amplifier via
immunomodulatory effects. Expert Rev Anti Infect Ther. 20(1), 17-21.
4. Boni, F.G., Hamdi, I., Koundi, L.M., Shrestha, K. and Xie, J., 2022. Cytokine
storm in tuberculosis and IL-6 involvement. Infect. Genet. Evol, 97, 105-166.
5. Esteban, Y. M., de Jong, J. L. O. & Tesher, M. S. An overview of
hemophagocytic lymphohistiocytosis. Pediatr. Ann.46, e309–e313 (2017).
6. Cohen, J., 1995. IL-12 deaths: explanation and a puzzle. Science. 270 (5238), 908-
908.
7. Ferrara, J.L., Abhyankar, S. and Gilliland, D.G., 1993. February. Cytokine storm
of graft-versus-host disease: a critical effector role for interleukin-1. Transplant.
Proc. 25(1) 1216-1217.
Journal Pre-proof
8. Shah, N. N., Dar, K. A., Quibtiya, S., Azad, A. M. U. D., Mushtaq, M., Bashir, S.
M., ... & Nabi, S. U. (2022). Repurposing of Mycobacterium indicus pranii for the
severe form of COVID‐19 patients in India: A cohort study. Journal of Medical
Virology, 94(5), 1906-1919.
9. Shah, N. N., Nabi, S. U., Rather, M. A., Kalwar, Q., Ali, S. I., Sheikh, W. M., ...
& Bashir, S. M. (2021). An update on emerging therapeutics to combat COVID‐
19. Basic & Clinical Pharmacology & Toxicology, 129(2), 104-129.
10. Elkhalifa, A. M., Shah, N. N., Khan, Z., Ali, S. I., Nabi, S. U., Bashir, S. M., ... &
Ahmed, E. M. (2023, March). Clinical Characterization and Outcomes of Patients
with Hypercreatinemia Affected by COVID-19. In Healthcare (Vol. 11, No. 7, p.
944). MDPI.
11. Elkhalifa, Ahmed ME, Showkat Ul Nabi, Naveed Nazir Shah, Khurshid Ahmad
Dar, Syed Quibtiya, Showkeen Muzamil Bashir, Sofi Imtiyaz Ali, Syed Taifa, and
Iqra Hussain. "Evaluation of Convalescent Plasma in the Management of Critically
Ill COVID-19 Patients (with No Detectable Neutralizing Antibodies Nab) in
Kashmir, India." In Healthcare, vol. 11, no. 3, p. 317. MDPI, 2023.
12. Shah, Naveed Nazir, Zaid Khan, Hashim Ahad, Abozer Y. Elderdery, Mohammad
N. Alomary, Banan Atwah, Zain Alhindi et al. "Mucormycosis an added burden to
Covid-19 Patients: An in-depth Systematic Review." Journal of infection and
public health (2022).
13. Ragab, D., Salah Eldin, H., Taeimah, M., Khattab, R. and Salem, R., 2020. The
COVID-19 cytokine storm; what we know so far. Front. Immunol. 1446-1456.
14. Liu, B., Li, M., Zhou, Z., Guan, X. and Xiang, Y., 2020b. Can we use interleukin-
6 (IL-6) blockade for coronavirus disease 2019 (COVID-19)-induced cytokine
release syndrome (CRS)?. J. Autoimmun. 111, 102452.
15. Zhang, B. et al. Immune phenotyping based on the neutrophil-to-lymphocyte ratio
and IgG level predicts disease severity and outcome for patients with COVID-
19.Front. Mol. Biosci.7, 157 (2020).
16. Jiang, Y., Rubin, L., Peng, T., Liu, L., Xing, X., Lazarovici, P. and Zheng, W.,
2022. Cytokine storm in COVID-19: from viral infection to immune responses,
diagnosis and therapy. Int. J. Biol. Sci, 18(2), 459.
17. Shen, W.X., Luo, R.C., Wang, J.Q. and Chen, Z.S., 2021. Features of cytokine
storm identified by distinguishing clinical manifestations in COVID-19. Public
Health Front. 9, 614.
Journal Pre-proof
18. Zhang, Y., Li, J., Zhan, Y., Wu, L., Yu, X., Zhang, W., ... & Lou, J. (2004).
Analysis of serum cytokines in patients with severe acute respiratory syndrome.
Infection and immunity, 72(8), 4410-4415.
19. Templin, C., Ghadri, J.R., Diekmann, J., Napp, L.C., Bataiosu, D.R., Jaguszewski,
M., Cammann, V.L., Sarcon, A., Geyer, V., Neumann, C.A. and Seifert, B., 2015.
Clinical features and outcomes of takotsubo (stress)
cardiomyopathy. NEJM. 373(10), 929-938.
20. Yang, L. et al. COVID-19: immunopathogenesis and Immunotherapeutics.Signal
Transduct. Target Ther.5, 128 (2020).
21. Wilk, A. J. et al. A single-cell atlas of the peripheral immune response in patients
with severe COVID-19.Nat. Med.26, 1070–1076 (2020).
22. Ronit, A. et al. Compartmental immunophenotyping in COVID-19 ARDS: a case
series.J. Allergy Clin. Immunol.147,81–91 (2021).
23. Zheng, H. et al. Virulence and pathogenesis of SARS-CoV-2 infection in rhesus
macaques: a nonhuman primate model of COVID-19 progression.PLoS Pathog.
16, e1008949 (2020).
24. Li, M. et al. Elevated exhaustion levels of NK and CD8(+) T cells as indicators for
progression and prognosis of COVID-19 disease.Front. Immunol.11, 580237
(2020).
25. Zheng, M. et al. Functional exhaustion of antiviral lymphocytes in COVID-19
patients.Cell. Mol. Immunol.17, 533–535 (2020).
26. Muhammad, A., Forcados, G.E., Sani, H., Ndidi, U.S., Adamu, A., Katsayal, B.S.,
Sadiq, I.Z., Abubakar, Y.S., Sulaiman, I., Abubakar, I.B. and Yusuf, A.P., 2022.
Epigenetic modifications associated with genes implicated in cytokine storm: The
potential biotherapeutic effects of vitamins and minerals in COVID‐19. J. Food
Biochem, 140-179.
27. Schwartzentruber, D.J., 2001. Guidelines for the safe administration of high-dose
interleukin-2. J. Immunother. Cancer. 24(4), 287-293.
28. Lee, D.W., Santomasso, B.D., Locke, F.L., Ghobadi, A., Turtle, C.J., Brudno, J.N.,
Maus, M.V., Park, J.H., Mead, E., Pavletic, S. and Go, W.Y., 2019. ASTCT
consensus grading for cytokine release syndrome and neurologic toxicity
associated with immune effector cells. Biol. Blood Marrow Transplant. 25(4),
625-638.
Journal Pre-proof
29. Lee, D.W., Gardner, R., Porter, D.L., Louis, C.U., Ahmed, N., Jensen, M., Grupp,
S.A. and Mackall, C.L., 2014. Current concepts in the diagnosis and management
of cytokine release syndrome. Blood, Am. J. Hematol. 124(2), 188-195.
30. Kumar, A., Sharma, A., Tirpude, N.V., Sharma, S., Padwad, Y.S. and Kumar, S.,
2022. Pharmaco-immunomodulatory interventions for averting cytokine storm-
linked disease severity in SARS-CoV-2 infection. Inflammopharmacology, 1-27.
31. Wang, S. et al. Characterization of neutralizing antibody with prophylactic and
therapeutic efficacy against SARS-CoV-2 in rhesus monkeys. Nat. Commun.11,
5752 (2020).
32. Brinkmann, V. et al. Neutrophil extracellular traps kill bacteria. Science 303, 1532–
1535 (2004).
33. Weiss, S. J. Tissue destruction by neutrophils.N. Engl. J. Med.320, 365–376
(1989).
34. Chen, Y. M. et al. Blood molecular markers associated with COVID-19
immunopathology and multi-organ damage.EMBO J.39, e105896 (2020).
35. Schulte-Schrepping, J. et al. Severe COVID-19 is marked by a dysregulated
myeloid cell compartment.Cell182, 1419–1440.e1423 (2020).
36. McElvaney, O. J. et al. Characterization of the inflammatory response to severe
COVID-19 illness. Am. J. Respir. Crit. Care Med.202, 812–821 (2020).
37. Palsson-McDermott, E. M. et al. Pyruvate kinase M2 regulates Hif-1alpha activity
and IL-1beta induction and is a critical determinant of the Warburg effect in LPS-
activated macrophages. Cell Metab.21, 347 (2015).
38. El-Qutob D, Alvarez-Arroyo L, Barreda I, Nieto M, Pin M, Poveda-Andrés JL,
Carrera-Hueso FJ. High incidence of pulmonary thromboembolism in hospitalized
SARS-CoV-2 infected patients despite thrombo-prophylaxis. Heart Lung. 2022;
53:77-82.
39. Mangalmurti, N. & Hunter, C. A. Cytokine storms: understanding COVID-19.
Immunity 53,19–25 (2020).
40. Ferrara, J. L., Abhyankar, S. & Gilliland, D. G. Cytokine storm of graft-versus-
host disease: a critical effector role for interleukin-1.Transplant. Proc.25, 1216–
1217 (1993).
41. Chousterman, B. G., Swirski, F. K. & Weber, G. F. Cytokine storm and sepsis
disease pathogenesis.Semin. Immunopathol.39, 517–528 (2017).
Journal Pre-proof
42. Kumar, V. Toll-like receptors in sepsis-associated cytokine storm and their
endogenous negative regulators as future immunomodulatory targets. Int.
Immunopharmacol. 89, 107087 (2020).
43. London, N. R. et al. Targeting Robo4-dependent Slit signaling to survive the
cytokine storm in sepsis and influenza. Sci. Transl. Med.2, 23ra19 (2010).
44. Imus, P. H. et al. Severe cytokine release syndrome after haploidentical peripheral
blood stem cell transplantation. Biol. Blood Marrow Transplant. 25, 2431–2437
(2019).
45. Wadia, P. P. & Tambur, A. R. Yin and yang of cytokine regulation in solid organ
graft rejection and tolerance. Clin. Lab. Med.28, 469–479, vii–viii (2008).
46. Davila, M. L. et al. Efficacy and toxicity management of 19-28z CAR T cell
therapy in B cell acute lymphoblastic leukemia. Sci. Transl. Med.6, 224ra225
(2014).
47. Grupp, S. A. et al. Chimeric antigen receptor-modified T cells for acute lymphoid
leukemia. N. Engl. J. Med.368, 1509–1518 (2013).
48. Qin, C. et al. Dysregulation of immune response in patients with coronavirus 2019
(COVID-19) in Wuhan, China.Clin. Infect. Dis.71, 762–768 (2020). 25. Wang, F.
et al. Characteristics of peripheral lymphocyte subset alteration in COVID-19
pneumonia.J. Infect. Dis.221, 1762–1769 (2020).
49. Hadjadj, J. et al. Impaired type I interferon activity and inflammatory responses in
severe COVID-19 patients. Science 369, 718–724 (2020).
50. Diao, B. et al. Reduction and functional exhaustion of T cells in patients with
coronavirus disease 2019 (COVID-19).Front. Immunol.11, 827 (2020).
51. Zhang, J. J. et al. Clinical characteristics of 140 patients infected with SARS-CoV-
2 in Wuhan, China. Allergy75, 1730–1741 (2020).
52. Fang, L., Karakiulakis, G. & Roth, M. Are patients with hypertension and diabetes
mellitus at increased risk for COVID-19 infection?Lancet Respir. Med. 8, e21
(2020).
53. Wang, K. et al. CD147-spike protein is a novel route for SARS-CoV-2 infection to
host cells.Signal Transduct. Target Ther.5, 283 (2020).
54. Norelli, M., Camisa, B., Barbiera, G., Falcone, L., Purevdorj, A., Genua, M.,
Sanvito, F., Ponzoni, M., Doglioni, C., Cristofori, P. and Traversari, C., 2018.
Monocyte-derived IL-1 and IL-6 are differentially required for cytokine-release
syndrome and neurotoxicity due to CAR T cells. Nat. Med. 24(6), 739-748.
Journal Pre-proof
55. Vadhan-Raj, S.A.R.O.J., Nathan, C.F., Sherwin, S.A., Oettgen, H.F. and Krown,
S.E., 1986. Phase I trial of recombinant interferon gamma by 1-hour iv
infusion. Cancer Treat. Rep. 70(5), 609-614.
56. Vignesh, R., Velu, V. and Sureban, S.M., 2021. Could Nutraceutical Approaches
Possibly Attenuate the Cytokine Storm in COVID-19 Patients? Front Cell Infect
Microbiol. 11, 45-54.
57. Arabi, Y.M., Shalhoub, S., Mandourah, Y., Al-Hameed, F., Al-Omari, A., Al
Qasim, E., Jose, J., Alraddadi, B., Almotairi, A., Al Khatib, K. and Abdulmomen,
A., 2020. Ribavirin and interferon therapy for critically ill patients with Middle
East respiratory syndrome: a multicenter observational study. Clin. Infect.
Dis. 70(9), 1837-1844.
58. WHO Expert Committee on the Selection, Use of Essential Medicines and World
Health Organization, 2014. The Selection and Use of Essential Medicines: Report
of the WHO Expert Committee, 2013 (including the 18th WHO Model List of
Essential Medicines and the 4th WHO Model List of Essential Medicines for
Children) (Vol. 985). World Health Organization.
59. Cornelissen, A., Kutyna, M., Cheng, Q., Sato, Y., Kawakami, R., Sakamoto, A.,
Kawai, K., Mori, M., Fernandez, R., Guo, L. and Pellegrini, D., 2022. Effects of
simulated COVID-19 cytokine storm on stent thrombogenicity. Cardiovasc.
Revascularization, 35, 129-138.
60. Wang, X. et al. Retraction Note to: SARS-CoV-2 infects T lymphocytes through
its spike protein-mediated membrane fusion.Cell. Mol. Immunol.17, 894 (2020).
61. Yeleswaram, S. et al. Inhibition of cytokine signaling by ruxolitinib and
implications for COVID-19 treatment.Clin. Immunol.218, 108517 (2020).
62. Seif, F. et al. JAK inhibition as a new treatment strategy for patients with COVID-
19.Int. Arch. Allergy Immunol. 181, 467–475 (2020).
63. Ramasamy, S. and Subbian, S., 2021. Critical determinants of cytokine storm and
type I interferon response in COVID-19 pathogenesis. Clin. Microbiol. Rev. 34(3),
299-305.
64. Schulert, G.S., Zhang, M., Fall, N., Husami, A., Kissell, D., Hanosh, A., Zhang,
K., Davis, K., Jentzen, J.M., Napolitano, L. and Siddiqui, J., 2016. Whole-exome
sequencing reveals mutations in genes linked to hemophagocytic
lymphohistiocytosis and macrophage activation syndrome in fatal cases of H1N1
influenza. J. Infect. Dis. 213(7), 1180-1188.
Journal Pre-proof
65. Shakoory, B., Carcillo, J.A., Chatham, W.W., Amdur, R.L., Zhao, H., Dinarello,
C.A., Cron, R.Q. and Opal, S.M., 2021. Interleukin-1 receptor blockade is
associated with reduced mortality in sepsis patients with features of the
macrophage activation syndrome: Re-analysis of a prior Phase III trial. Crit. Care
Med. 44(2), 275-281.
66. Teijaro, J.R., Walsh, K.B., Cahalan, S., Fremgen, D.M., Roberts, E., Scott, F.,
Martinborough, E., Peach, R., Oldstone, M.B. and Rosen, H., 2011. Endothelial
cells are central orchestrators of cytokine amplification during influenza virus
infection. Cell. 146(6), 980-991.
67. Yao, X.H., Li, T.Y., He, Z.C., Ping, Y.F., Liu, H.W., Yu, S.C., Mou, H.M., Wang,
L.H., Zhang, H.R., Fu, W.J. and Luo, T., 2020. A pathological report of three
COVID-19 cases by minimal invasive autopsies. Chin. J. Pathol. 49(5), 411-417.
68. Copaescu, A., Smibert, O., Gibson, A., Phillips, E.J. and Trubiano, J.A., 2020. The
role of IL-6 and other mediators in the cytokine storm associated with SARS-CoV-
2 infection. J. Allergy Clin. Immunol. Pract. 146(3), 518-534.
69. Zoller, E.E., Lykens, J.E., Terrell, C.E., Aliberti, J., Filipovich, A.H., Henson, P.M.
and Jordan, M.B., 2011. Hemophagocytosis causes a consumptive anemia of
inflammation. J. Exp. Med. 208(6), 1203-1214.
70. Zuccari, S., Damiani, E., Domizi, R., Scorcella, C., D’Arezzo, M., Carsetti, A.,
Pantanetti, S., Vannicola, S., Casarotta, E., Ranghino, A. and Donati, A., 2020.
Changes in cytokines, haemodynamics and microcirculation in patients with
sepsis/septic shock undergoing continuous renal replacement therapy and blood
purification with CytoSorb. Blood Purif. 49(1-2), 107-113.
71. Doherty, G.M., Lange, J.R., Langstein, H.N., Alexander, H.R., Buresh, C.M. and
Norton, J.A., 1992. Evidence for IFN-gamma as a mediator of the lethality of
endotoxin and tumor necrosis factor-alpha. J. Immunol. 149(5), 1666-1670.
72. Atkins, M.B., 2002, June. Interleukin-2: clinical applications. In Seminars in
oncology. 29(3), 12-17. WB Saunders.
73. Reiff, D.D., Zhang, M., Smitherman, E.A., Mannion, M.L., Stoll, M.L., Weiser, P.
and Cron, R.Q., 2022. A Rare STXBP2 Mutation in Severe COVID-19 and
Secondary Cytokine Storm Syndrome. Life, 12(2), 149.
74. Winkler, U., Jensen, M., Manzke, O., Schulz, H., Diehl, V. and Engert, A., 1999.
Cytokine-release syndrome in patients with B-cell chronic lymphocytic leukemia
Journal Pre-proof
and high lymphocyte counts after treatment with an anti-CD20 monoclonal
antibody (rituximab, IDEC-C2B8). Blood, Am. J. Hematol. 94(7), 2217-2224.
75. Teachey, D.T., Rheingold, S.R., Maude, S.L., Zugmaier, G., Barrett, D.M., Seif,
A.E., Nichols, K.E., Suppa, E.K., Kalos, M., Berg, R.A. and Fitzgerald, J.C., 2013.
Cytokine release syndrome after blinatumomab treatment related to abnormal
macrophage activation and ameliorated with cytokine-directed therapy. Blood,Am.
J. Hematol. 121(26), 5154-5157.
76. Kang, S., Tanaka, T., Narazaki, M. and Kishimoto, T., 2019. Targeting interleukin-
6 signaling in clinic. Immunity. 50(4), 1007-1023.
77. Arıkan, F.A., Akdağ, G., Çetiner, M., Uysal, N. and Kabay, S.C., 2022. Isolated
corpus callosum lesion associated with cytokine storm in COVID-19. In Baylor
University Medical Center Proceedings 35(3), 337-338.
78. Martinon, F., Pétrilli, V., Mayor, A., Tardivel, A. and Tschopp, J., 2006. Gout-
associated uric acid crystals activate the NALP3
inflammasome. Nature. 440(7081), 237-241.
79. Frank, D. and Vince, J.E., 2019. Pyroptosis versus necroptosis: similarities,
differences, and crosstalk. Cell Death Differ. 26(1), 99-114.
80. Stolarski, A.E., Kim, J., Zhang, Q. and Remick, D.G., 2021. Cytokine Drizzle—
The Rationale for Abandoning “Cytokine Storm”. Shock. 56(5), 667-672.
81. Mazodier, K., Marin, V., Novick, D., Farnarier, C., Robitail, S., Schleinitz, N.,
Veit, V., Paul, P., Rubinstein, M., Dinarello, C.A. and Harlé, J.R., 2005. Severe
imbalance of IL-18/IL-18BP in patients with secondary hemophagocytic
syndrome. Blood. 106(10), 3483-3489.
82. Pashaki, P.A., Shirbandi, K., Ramezani, S., Rahim, F. and Jamalpoor, Z., 2022.
SARS-Cov2-Induced Cytokine Storm and Schizophrenia, Could There be a
Connection? Arch. Psychiatry res., 58(1), 107-117.
83. Dinarello, C., Novick, D., Kim, S. and Kaplanski, G., 2013. Interleukin-18 and IL-
18 binding protein. Front. Immunol. 4, 289.
84. Ratheesh, M., Sunil, S., Sheethal, S., Jose, S.P., Sandya, S., Ghosh, O.S.N., Rajan,
S., Jagmag, T. and Tilwani, J., 2022. Anti-inflammatory and anti-COVID-19 effect
of a novel polyherbal formulation (Imusil) via modulating oxidative stress,
inflammatory mediators and cytokine storm. Inflammopharmacology, 1-12.
Journal Pre-proof
85. Gorelik, M., Torok, K.S., Kietz, D.A. and Hirsch, R., 2011. Hypocomplementemia
associated with macrophage activation syndrome in systemic juvenile idiopathic
arthritis and adult onset still’s disease: 3 cases. J. Rheumatol. 38(2), 396-397.
86. Porter, D.L., Hwang, W.T., Frey, N.V., Lacey, S.F., Shaw, P.A., Loren, A.W.,
Bagg, A., Marcucci, K.T., Shen, A., Gonzalez, V. and Ambrose, D., 2015.
Chimeric antigen receptor T cells persist and induce sustained remissions in
relapsed refractory chronic lymphocytic leukemia. Sci. Transl. Med. 7(303), 303-
139.
87. Giavridis, T., van der Stegen, S.J., Eyquem, J., Hamieh, M., Piersigilli, A. and
Sadelain, M., 2018. CAR T cell–induced cytokine release syndrome is mediated
by macrophages and abated by IL-1 blockade. Nat. Med. 24(6), 731-738.
88. Singh, N., Hofmann, T.J., Gershenson, Z., Levine, B.L., Grupp, S.A., Teachey,
D.T. and Barrett, D.M., 2017. Monocyte lineage–derived IL-6 does not affect
chimeric antigen receptor T-cell function. Cytotherapy. 19(7), 867-880.
89. Suntharalingam, G., Perry, M.R., Ward, S., Brett, S.J., Castello-Cortes, A.,
Brunner, M.D. and Panoskaltsis, N., 2006. Cytokine storm in a phase 1 trial of the
anti-CD28 monoclonal antibody TGN1412. NEJM. 355(10), 1018-1028.
90. Liu, Q., Zhou, Y.H. and Yang, Z.Q., 2016. The cytokine storm of severe influenza
and development of immunomodulatory therapy. Cell. Mol. Immunol. 13(1), 3-
10.
91. Xu, X.J. and Tang, Y.M., 2014. Cytokine release syndrome in cancer
immunotherapy with chimeric antigen receptor engineered T cells. Cancer
Lett. 343(2), 172-178.
92. Frey, N.V. and Porter, D.L., 2016. Cytokine release syndrome with novel
therapeutics for acute lymphoblastic leukemia. Hematology. Hematology Am Soc
Hematol Educ Program. 2016(1), 567-572.
93. Fenizia, C., Galbiati, S., Vanetti, C., Vago, R., Clerici, M., Tacchetti, C. and
Daniele, T., 2022. Cyclosporine A Inhibits Viral Infection and Release as Well as
Cytokine Production in Lung Cells by Three SARS-CoV-2 Variants. Microbiol.
Spectr. 10(1), 504-521.
94. Bayraktar, N., Turan, H., Bayraktar, M., Ozturk, A. and Erdoğdu, H., 2022.
Analysis of serum cytokine and protective vitamin D levels in severe cases of
COVID‐19. J Med Viral, 94(1), 154-160.
Journal Pre-proof
95. Ojemolon, P.E., Kalidindi, S., Ahlborn, T.A., Aihie, O.P. and Awoyomi, M.I.,
2022. Cytokine Release Syndrome Following Blinatumomab
Therapy. Cureus. 14(1), 23-31.
96. Guo, H., Qian, L. and Cui, J., 2022. Focused evaluation of the roles of macrophages
in chimeric antigen receptor (CAR) T cell therapy associated cytokine release
syndrome. Cancer Biol. Ther. 19(3), 333.
97. Khokhar, M., Tomo, S. and Purohit, P., 2022. MicroRNAs based regulation of
cytokine regulating immune expressed genes and their transcription factors in
COVID-19. Meta gene. 31, 199-203.
98. Khani, E. and Entezari-Maleki, T., 2022. Fluvoxamine and long COVID-19; a new
role for sigma-1 receptor (S1R) agonists. Mol. Psychiatry.1-1.
99. Madsen, N.H., Gad, M. and Larsen, J., 2022. Development of a flow cytometry-
based potency assay for prediction of cytokine storms induced by biosimilar
monoclonal antibodies. J. Immunol. Methods, 502, 113-131.
100. Cataneo, A.H.D., Bordignon, J., Wowk, P.F. and Silveira, G.F., 2022. In
Vitro Cytokine Production by Dengue-Infected Human Monocyte-Derived
Dendritic Cells. In Dengue Virus. 223-234. Humana, New York, NY.
101. Tan, L.L., Lee, M.P., Goh, S.H., Lim, H.H., Goh, A. and Chong, K.W., 2022.
Cytokine release syndrome–a unique entity of Augmentin hypersensitivity
reaction. Asia Pac. Allergy. 12(1), 12-26.
102. Polizzotto, M.N., Uldrick, T.S., Wang, V., Aleman, K., Wyvill, K.M.,
Marshall, V., Pittaluga, S., O’Mahony, D., Whitby, D., Tosato, G. and Steinberg,
S.M., 2013. Human and viral interleukin-6 and other cytokines in Kaposi sarcoma
herpesvirus-associated multicentric Castleman disease. Blood, Hematology Am
Soc. 122(26), 4189-4198.
103. Dispenzieri, A. and Fajgenbaum, D.C., 2020. Overview of Castleman
disease. Blood, 135(16), 1353-1364.
104. Thomas, D., Abraham, A., Joseph, A., Dommy, A. and Shahna, N., 2022.
Periodontal Disease as a factor in morbidity of Covid-19: A Review.
J. Oral Maxillofac. Pathol. 44-48.
105. Rossi, C.M., Lenti, M.V. and Di Sabatino, A., 2022. Adult anaphylaxis: a
state-of-the-art review. Eur. J. Intern. Med. 9(2), 123-145.
106. Zhang, M., Bracaglia, C., Prencipe, G., Bemrich-Stolz, C.J., Beukelman, T.,
Dimmitt, R.A., Chatham, W.W., Zhang, K., Li, H., Walter, M.R. and De Benedetti,
Journal Pre-proof
F., 2016. A heterozygous RAB27A mutation associated with delayed cytolytic
granule polarization and hemophagocytic
lymphohistiocytosis. J. Immunol. 196(6), 2492-2503.
107. Kaufman, K.M., Linghu, B., Szustakowski, J.D., Husami, A., Yang, F.,
Zhang, K., Filipovich, A.H., Fall, N., Harley, J.B., Nirmala, N.R. and Grom, A.A.,
2014. Whole‐exome sequencing reveals overlap between macrophage activation
syndrome in systemic juvenile idiopathic arthritis and familial hemophagocytic
lymphohistiocytosis. Arthritis Rheumatol. 66(12), 3486-3495.
108. Saeed, M.A.M., Mohamed, A.H. and Owaynat, A.H., 2022. Cholecalciferol
level and its impact on COVID-19 patients. EJIM. 34(1), 1-8.
109. Bawaskar, H.S. and Bawaskar, P.H., 2022. Role of methylene blue in the
management of mild, moderate and severe COVID-19 disease. Fam. Med. Prim.
Care Rev. 11(2), 812-821.
110. Faitelson, Y. and Grunebaum, E., 2014. Hemophagocytic
lymphohistiocytosis and primary immune deficiency disorders. J. Clin.
Immunol. 155(1), 118-125.
111. Iwaki, N., Fajgenbaum, D.C., Nabel, C.S., Gion, Y., Kondo, E., Kawano, M.,
Masunari, T., Yoshida, I., Moro, H., Nikkuni, K. and Takai, K., 2016.
Clinicopathologic analysis of TAFRO syndrome demonstrates a distinct subtype
of HHV‐8‐negative multicentric Castleman disease. Am. J. Hematol. 91(2), 220-
226.
112. Thepmankorn, P., Bach, J., Lasfar, A., Zhao, X., Souayah, S., Chong, Z.Z.
and Souayah, N., 2021. Cytokine storm induced by SARS-CoV-2 infection: The
spectrum of its neurological manifestations. Cytokine. 138, 155-204.
113. Hu, B., Huang, S. and Yin, L., 2021. The cytokine storm and COVID‐
19. J Med Virol. 93(1), 250-256.
114. Kim, J.S., Lee, J.Y., Yang, J.W., Lee, K.H., Effenberger, M., Szpirt, W.,
Kronbichler, A. and Shin, J.I., 2021. Immunopathogenesis and treatment of
cytokine storm in COVID-19. Theranostics. 11(1), 316-321.
115. Coon, B.G., Baeyens, N., Han, J., Budatha, M., Ross, T.D., Fang, J.S., Yun,
S., Thomas, J.L. and Schwartz, M.A., 2015. Intramembrane binding of VE-
cadherin to VEGFR2 and VEGFR3 assembles the endothelial mechanosensory
complex. J. Cell Biol. 208(7), 975-986.
Journal Pre-proof
116. Khan, M.A., Khan, Z.A., Charles, M., Pratap, P., Naeem, A., Siddiqui, Z.,
Naqvi, N. and Srivastava, S., 2021. Cytokine storm and mucus hypersecretion in
COVID-19: review of mechanisms. J. Inflamm. Res. 14, 175.
117. Ragab, D., Salah Eldin, H., Taeimah, M., Khattab, R. and Salem, R., 2020.
The COVID-19 cytokine storm; what we know so far. Front. Immunol. 1446-
1456.
118. Ishikawa, T., 2012. Clinical preparedness for cytokine storm induced by the
highly pathogenic H5N1 influenza virus. Pharmacogenomics J. 3(6), 1000-1131.
119. Kalaiyarasu, S., Kumar, M., Senthil Kumar, D., Bhatia, S., Dash, S.K., Bhat,
S., Khetan, R.K. and Nagarajan, S., 2016. Highly pathogenic avian influenza
H5N1 virus induces cytokine dysregulation with suppressed maturation of chicken
monocyte‐derived dendritic cells. Microbiol. Immunol. 60(10), 687-693.
120. Hafezi, B., Chan, L., Knapp, J.P., Karimi, N., Alizadeh, K., Mehrani, Y.,
Bridle, B.W. and Karimi, K., 2021. Cytokine Storm Syndrome in SARS-CoV-2
Infections: A Functional Role of Mast Cells. Cells. 10(7), 1761.
121. Barnes, P. J. (2008). Immunology of asthma and chronic obstructive
pulmonary disease. Nature Reviews Immunology, 8(3), 183–192.
122. Holgate, S. T. (2012). Innate and adaptive immune responses in asthma.
Nature Medicine, 18(5), 673–683.
123. Wynn, T. A. (2011). Integrating mechanisms of pulmonary fibrosis. Journal
of Experimental Medicine, 208(7), 1339–1350.
124. Chung, K. F., & Adcock, I. M. (2008). Multifaceted mechanisms in COPD:
inflammation, immunity, and tissue repair and destruction. European Respiratory
Journal, 31(6), 1334–1356.
125. Matthay, M. A., & Zemans, R. L. (2011). The acute respiratory distress
syndrome: pathogenesis and treatment. Annual Review of Pathology: Mechanisms
of Disease, 6, 147–163.
126. Short, K. R., & Kroeze, E. J. B. V. (2014). Interactions of non-typeable
Haemophilus influenzae with host innate defense mechanisms. Frontiers in
Immunology, 5, 234.
127. Khadke, S., Ahmed, N., Ahmed, N., Ratts, R., Raju, S., Gallogly, M., de
Lima, M. and Sohail, M.R., 2020. Harnessing the immune system to overcome
cytokine storm and reduce viral load in COVID-19: a review of the phases of
illness and therapeutic agents. Virol. J. 17(1), 1-18.
Journal Pre-proof
128. Chen, G., Wu, D.I., Guo, W., Cao, Y., Huang, D., Wang, H., Wang, T.,
Zhang, X., Chen, H., Yu, H. and Zhang, X., 2020a. Clinical and immunological
features of severe and moderate coronavirus disease
2019. J. Clin. Investig. 130(5), 2620-2629.
129. Chen, L.D., Zhang, Z.Y., Wei, X.J., Cai, Y.Q., Yao, W.Z., Wang, M.H.,
Huang, Q.F. and Zhang, X.B., 2020b. Association between cytokine profiles and
lung injury in COVID-19 pneumonia. Respir. Res. 21(1), 1-8.
130. Chen, N., Zhou, M., Dong, X., Qu, J., Gong, F., Han, Y., Qiu, Y., Wang, J.,
Liu, Y., Wei, Y. and Yu, T., 2020c. Epidemiological and clinical characteristics of
99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive
study. Lancet. 395(10223), 507-513.
131. Kounis, N.G., Koniari, I., de Gregorio, C., Assimakopoulos, S.F., Velissaris,
D., Hung, M.Y., Mplani, V., Saba, L., Brinia, A., Kouni, S.N. and Gogos, C., 2021.
COVID-116 Lau, S.K., Lau, C.C., Chan, K.H., Li, C.P., Chen, H., Jin, D.Y., Chan,
J.F., Woo, P.C. and Yuen, K.Y., 2013. Delayed induction of proinflammatory
cytokines and suppression of innate antiviral response by the novel Middle East
respiratory syndrome coronavirus: implications for pathogenesis and
treatment. J. Gen. Virol. 94(12), 2679-2690.
132. Lukan, N., 2020. “Cytokine storm”, not only in COVID-19 patients. Mini-
review. Immunol. Lett. 228, 38-44.
133. De la Rica, R., Borges, M. and Gonzalez-Freire, M., 2020. COVID-19: in the
eye of the cytokine storm. Front. Immunol. 2313.
134. Fara, A., Mitrev, Z., Rosalia, R.A. and Assas, B.M., 2020. Cytokine storm
and COVID-19: a chronicle of pro-inflammatory cytokines. Open Biol. 10(9),
200160.
135. Cantan, B., Luyt, C.E. and Martin-Loeches, I., 2019, August. Influenza
infections and emergent viral infections in intensive care unit. Semin Respir Crit
Care Med. 40 (4), 488-497.
136. Opal SM, DePalo VA. Anti-inflammatory cytokines. Chest.
2000;117(4):1162-1172.
137. Lordan, R., Tsoupras, A. and Zabetakis, I., 2021. Platelet activation and
prothrombotic mediators at the nexus of inflammation and atherosclerosis:
Potential role of antiplatelet agents. Blood Rev. 45, 100-104.
Journal Pre-proof
138. Hussman, J.P., 2020. Cellular and molecular pathways of COVID-19 and
potential points of therapeutic intervention. Front. Pharmacol. 1169.
139. Mehta P, McAuley DF, Brown M, et al. COVID-19: consider cytokine storm
syndromes and immunosuppression. Lancet. 2020;395(10229):1033-1034.
140. Eljaaly, K., Malibary, H., Alsulami, S., Albanji, M., Badawi, M. and Al-
Tawfiq, J.A., 2021. Description and analysis of cytokine storm in registered
COVID-19 clinical trials: a systematic review. Pathogens. 10(6), 692.
141. Zuo, Y., Yalavarthi, S., Shi, H., Gockman, K., Zuo, M., Madison, J.A., Blair,
C., Weber, A., Barnes, B.J., Egeblad, M. and Woods, R.J., 2020. Neutrophil
extracellular traps in COVID-19. JCI insight, 5(11).
142. Ruan Q, Yang K, Wang W, Jiang L, Song J. Clinical predictors of mortality
due to COVID-19 based on an analysis of data of 150 patients from Wuhan, China.
Intensive Care Med. 2020;46(5):846-848.
143. Drexler, J.F., Corman, V.M. and Drosten, C., 2014. Ecology, evolution and
classification of bat coronaviruses in the aftermath of SARS. Antivir. Res. 101, 45-
56.
144. Gao, Y., Wang, C., Kang, K., Peng, Y., Luo, Y., Liu, H., Yang, W., Zhao,
M. and Yu, K., 2021. Cytokine storm may not be the chief culprit for the
deterioration of COVID-19. Viral Immunol. 34(5), 336-341.
145. Gao, C., Zhu, L., Jin, C.C., Tong, Y.X., Xiao, A.T. and Zhang, S., 2020.
Proinflammatory cytokines are associated with prolonged viral RNA shedding in
COVID-19 patients. J. Clin. Immunol. 221, 108611.
146. Taylor, D.R., 2006. Obstacles and advances in SARS vaccine
development. Vaccine. 24(7), 863-871.
147. Wong, C.K., Lam, C.W.K., Wu, A.K.L., Ip, W.K., Lee, N.L.S., Chan, I.H.S.,
Lit, L.C.W., Hui, D.S.C., Chan, M.H.M., Chung, S.S.C. and Sung, J.J.Y., 2004.
Plasma inflammatory cytokines and chemokines in severe acute respiratory
syndrome. Clin. Exp. Immunol., 136(1), 95-103.
148. Sun, X., Wang, T., Cai, D., Hu, Z., Liao, H., Zhi, L., Wei, H., Zhang, Z., Qiu,
Y., Wang, J. and Wang, A., 2020. Cytokine storm intervention in the early stages
of COVID-19 pneumonia. Cytokine Growth Factor Rev. 53, 38-42.
149. Chan, J.F., Lau, S.K., To, K.K., Cheng, V.C., Woo, P.C. and Yuen, K.Y.,
2015. Middle East respiratory syndrome coronavirus: another zoonotic
betacoronavirus causing SARS-like disease. Clin. Microbiol. Rev. 28(2), 465-522.
Journal Pre-proof
150. Mahallawi, W.H., Khabour, O.F., Zhang, Q., Makhdoum, H.M. and Suliman,
B.A., 2018. MERS-CoV infection in humans is associated with a pro-
inflammatory Th1 and Th17 cytokine profile. Cytokine. 104, 8-13.
151. Iannaccone, G., Scacciavillani, R., Del Buono, M.G., Camilli, M., Ronco, C.,
Lavie, C.J., Abbate, A., Crea, F., Massetti, M. and Aspromonte, N., 2020.
Weathering the cytokine storm in COVID-19: therapeutic
implications. Cardiorenal Med. 10(5), 277-287.
152. Liu, B., Li, M., Zhou, Z., Guan, X. and Xiang, Y., 2020b. Can we use
interleukin-6 (IL-6) blockade for coronavirus disease 2019 (COVID-19)-induced
cytokine release syndrome (CRS)?. J. Autoimmun. 111, 102452.
153. Ryabkova, V.A., Churilov, L.P. and Shoenfeld, Y., 2021. Influenza infection,
SARS, MERS and COVID-19: cytokine storm–the common denominator and the
lessons to be learned. J. Clin. Immunol.223, 108-152.
154. Zeng, H., Belser, J.A., Goldsmith, C.S., Gustin, K.M., Veguilla, V., Katz,
J.M. and Tumpey, T.M., 2015. A (H7N9) virus results in early induction of
proinflammatory cytokine responses in both human lung epithelial and endothelial
cells and shows increased human adaptation compared with avian H5N1 virus. J
Virol. 89(8), 4655-4667.
155. Beigel, J. and Bray, M., 2008. Current and future antiviral therapy of severe
seasonal and avian influenza. Antivir. Res. 78(1), 91-102.
156. Peiris, J.S.M., Yu, W.C., Leung, C.W., Cheung, C.Y., Ng, W.F., Nicholls,
J.A., Ng, T.K., Chan, K.H., Lai, S.T., Lim, W.L. and Yuen, K.Y., 2004. Re-
emergence of fatal human influenza A subtype H5N1 disease. Lancet. 363(9409),
617-619.
157. D'Elia, R.V., Harrison, K., Oyston, P.C., Lukaszewski, R.A. and Clark, G.C.,
2013. Targeting the “cytokine storm” for therapeutic benefit. Clin. Vaccine
Immunol. 20(3), 319-327.
158. Jose, R.J. and Manuel, A., 2020. COVID-19 cytokine storm: the interplay
between inflammation and coagulation. Lancet Respir. Med. 8(6), 46-47.
159. Stockman, L.J., Bellamy, R. and Garner, P., 2006. SARS: systematic review
of treatment effects. PLoS medicine. 3(9), 343.
160. Falzarano, D., De Wit, E., Rasmussen, A.L., Feldmann, F., Okumura, A.,
Scott, D.P., Brining, D., Bushmaker, T., Martellaro, C., Baseler, L. and Benecke,
Journal Pre-proof
A.G., 2013. Treatment with interferon-α2b and ribavirin improves outcome in
MERS-CoV–infected rhesus macaques. Nat. Med. 19(10), 1313-1317.
161. Omrani, A.S., Saad, M.M., Baig, K., Bahloul, A., Abdul-Matin, M.,
Alaidaroos, A.Y., Almakhlafi, G.A., Albarrak, M.M., Memish, Z.A. and Albarrak,
A.M., 2014. Ribavirin and interferon alfa-2a for severe Middle East respiratory
syndrome coronavirus infection: a retrospective cohort study. Lancet
Infect. Dis. 14(11), 1090-1095.
162. Davidson, S., McCabe, T.M., Crotta, S., Gad, H.H., Hessel, E.M., Beinke,
S., Hartmann, R. and Wack, A., 2016. IFN λ is a potent anti‐influenza therapeutic
without the inflammatory side effects of IFN α treatment. EMBO Mol. Med. 8(9),
1099-1112.
163. Blazek, K., Eames, H.L., Weiss, M., Byrne, A.J., Perocheau, D., Pease, J.E.,
Doyle, S., McCann, F., Williams, R.O. and Udalova, I.A., 2015. IFN-λ resolves
inflammation via suppression of neutrophil infiltration and IL-1β production. J.
Exp. Med. 212(6), 845-853.
164. Song, N., Wakimoto, H., Rossignoli, F., Bhere, D., Ciccocioppo, R., Chen,
K.S., Khalsa, J.K., Mastrolia, I., Samarelli, A.V., Dominici, M. and Shah, K., 2021.
Mesenchymal stem cell immunomodulation: In pursuit of controlling COVID-19
related cytokine storm. Stem Cells. 39(6), 707-722.
165. Auyeung, T.W., Lee, J.S., Lai, W.K., Choi, C.H., Lee, H.K., Lee, J.S., Li,
P.C., Lok, K.H., Ng, Y.Y., Wong, W.M. and Yeung, Y.M., 2005. The use of
corticosteroid as treatment in SARS was associated with adverse outcomes: a
retrospective cohort study. J. Infect. 51(2), 98-102.
166. Ho, J.C., Ooi, G.C., Mok, T.Y., Chan, J.W., Hung, I., Lam, B., Wong, P.C.,
Li, P.C., Ho, P.L., Lam, W.K. and Ng, C.K., 2003. High–dose pulse versus
nonpulse corticosteroid regimens in severe acute respiratory syndrome. Am. J.
Respir. Crit. Care Med.168(12), 1449-1456.
167. Yam, L.Y.C., Lau, A.C.W., Lai, F.Y.L., Shung, E., Chan, J., Wong, V. and
Hong Kong Hospital Authority SARS Collaborative Group (HASCOG), 2007.
Corticosteroid treatment of severe acute respiratory syndrome in Hong
Kong. J. Infect. 54(1), 28-39.
168. Chen, R.C., Tang, X.P., Tan, S.Y., Liang, B.L., Wan, Z.Y., Fang, J.Q. and
Zhong, N., 2006. Treatment of severe acute respiratory syndrome with
glucosteroids: the Guangzhou experience. Chest. 129(6), 1441-1452.
Journal Pre-proof
169. Zhao, J.P., Hu, Y., Du, R.H., Chen, Z.S., Jin, Y., Zhou, M., Zhang, J., Qu,
J.M. and Cao, B., 2020. Expert consensus on the use of corticosteroid in patients
with 2019-nCoV pneumonia. Tuberc Respir Dis. 43(3), 183-184.
170. Shimabukuro-Vornhagen, A., Gödel, P., Subklewe, M., Stemmler, H.J.,
Schlößer, H.A., Schlaak, M., Kochanek, M., Böll, B. and von Bergwelt-Baildon,
M.S., 2018. Cytokine release syndrome. J. Immunother. Canc. 6(1), 1-14.
171. Zhao, Z., Wei, Y. and Tao, C., 2021. An enlightening role for cytokine storm
in coronavirus infection. J. Clin. Immunol. 222, 108-115.
172. Biggioggero, M., Crotti, C., Becciolini, A. and Favalli, E.G., 2019.
Tocilizumab in the treatment of rheumatoid arthritis: an evidence-based review
and patient selection. Drug Des. Devel. Ther. 13, 57.
173. Tanaka, T., Narazaki, M. and Kishimoto, T., 2016. Immunotherapeutic
implications of IL-6 blockade for cytokine storm. Immunotherapy. 8(8), 959-970.
174. McDermott, J.E., Mitchell, H.D., Gralinski, L.E., Eisfeld, A.J., Josset, L.,
Bankhead, A., Neumann, G., Tilton, S.C., Schäfer, A., Li, C. and Fan, S., 2016.
The effect of inhibition of PP1 and TNFα signaling on pathogenesis of SARS
coronavirus. BMC Syst. Biol. 10(1), 1-12.
175. Udalova, I., Monaco, C., Nanchahal, J. and Feldmann, M., 2016. Anti-TNF
therapy. Microbiol. Spectr.22-25.
176. Bifulco, M., Fiore, D., Piscopo, C., Gazzerro, P. and Proto, M.C., 2021.
Commentary: Use of cannabinoids to treat acute respiratory distress syndrome and
cytokine storm associated with coronavirus disease-2019. Front. Pharmacol. 12,
145-156.
177. Channappanavar, R., Fehr, A.R., Vijay, R., Mack, M., Zhao, J., Meyerholz,
D.K. and Perlman, S., 2016. Dysregulated type I interferon and inflammatory
monocyte-macrophage responses cause lethal pneumonia in SARS-CoV-infected
mice. Cell Host Microbe. 19(2), 181-193.
178. Jiang, Y., Rubin, L., Peng, T., Liu, L., Xing, X., Lazarovici, P. and Zheng,
W., 2022. Cytokine storm in COVID-19: from viral infection to immune
responses, diagnosis and therapy. Int. J. Biol. Sci, 18(2), 459.
179. Pottoo, F.H., Abu-Izneid, T., Ibrahim, A.M., Javed, M.N., AlHajri, N. and
Hamrouni, A.M., 2021. Immune system response during viral Infections:
Immunomodulators, cytokine storm (CS) and Immunotherapeutics in COVID-
19. SPJ, 29(2), 173-187.
Journal Pre-proof
180. Davidson, S., Maini, M.K. and Wack, A., 2015. Disease-promoting affects
of type I interferons in viral, bacterial, and coinfections. J. Interferon Cytokine
Res. 35(4), 252-264.
181. Meftahi, G.H., Bahari, Z., Jangravi, Z. and Iman, M., 2021. A vicious circle
between oxidative stress and cytokine storm in acute respiratory distress syndrome
pathogenesis at COVID-19 infection. Ukr Biochem J. 93(1), 18-29.
182. Chau, A.S., Weber, A.G., Maria, N.I., Narain, S., Liu, A., Hajizadeh, N.,
Malhotra, P., Bloom, O., Marder, G. and Kaplan, B., 2021. The longitudinal
immune response to coronavirus disease 2019: chasing the cytokine
storm. Arthritis Rheumatol. 73(1), 23-35.
183. Savla, S.R., Prabhavalkar, K.S. and Bhatt, L.K., 2021. Cytokine storm
associated coagulation complications in COVID-19 patients: Pathogenesis and
Management. Expert Rev Anti Infect Ther. 19(11), 1397-1413.
184. Imai, Y., Kuba, K., Neely, G.G., Yaghubian-Malhami, R., Perkmann, T.,
van Loo, G., Ermolaeva, M., Veldhuizen, R., Leung, Y.C., Wang, H. and Liu, H.,
2008. Identification of oxidative stress and Toll-like receptor 4 signaling as a key
pathway of acute lung injury. Cell. 133(2), 235-249.
185. Shirey, K.A., Perkins, D.J., Lai, W., Zhang, W., Fernando, L.R., Gusovsky,
F., Blanco, J.C. and Vogel, S.N., 2019. Influenza “trains” the host for enhanced
susceptibility to secondary bacterial infection. mBio. 10(3), 10-19.
186. Maceyka, M., Harikumar, K.B., Milstien, S. and Spiegel, S., 2012.
Sphingosine-1-phosphate signaling and its role in disease. Trends Cell Biol. 22(1),
50-60.
187. Walsh, K.B., Teijaro, J.R., Rosen, H. and Oldstone, M., 2011. Quelling the
storm: utilization of sphingosine-1-phosphate receptor signaling to ameliorate
influenza virus-induced cytokine storm. Immunol. Res. 51(1), 15-25.
188. Ben-Mordechai, T., Palevski, D., Glucksam-Galnoy, Y., Elron-Gross, I.,
Margalit, R. and Leor, J., 2015. Targeting macrophage subsets for infarct repair. J.
Cardiovasc. Pharmacol. Ther. 20(1), 36-51.
189. Lee, J.W., Fang, X., Krasnodembskaya, A., Howard, J.P. and Matthay, M.A.,
2011. Concise review: mesenchymal stem cells for acute lung injury: role of
paracrine soluble factors. Stem cells. 29(6), 913-919.
190. Leuschner, F., Courties, G., Dutta, P., Mortensen, L.J., Gorbatov, R., Sena,
B., Novobrantseva, T.I., Borodovsky, A., Fitzgerald, K., Koteliansky, V. and
Journal Pre-proof
Iwamoto, Y., 2015. Silencing of CCR2 in myocarditis. Eur Heart J. 36(23), 1478-
1488.
191. Leuschner, F., Dutta, P., Gorbatov, R., Novobrantseva, T.I., Donahoe, J.S.,
Courties, G., Lee, K.M., Kim, J.I., Markmann, J.F., Marinelli, B. and Panizzi, P.,
2011. Therapeutic siRNA silencing in inflammatory monocytes in
mice. Nat. Biotechnol. 29(11), 1005-1010.
192. London, N.R., Zhu, W., Bozza, F.A., Smith, M.C., Greif, D.M., Sorensen,
L.K., Chen, L., Kaminoh, Y., Chan, A.C., Passi, S.F. and Day, C.W., 2010.
Targeting Robo4-dependent Slit signaling to survive the cytokine storm in sepsis
and influenza. Sci. Transl. Med.2(23), 19-23.
Journal Pre-proof
S.No
Disease
Criteria
References
1)
Viral Haemorrhagic
Fever
Haemorrhage, disseminated intravascular coagulation, Immune
suppression, higher levels of Ferritin and C-Reactive Protein
11, 12, 205
2)
Dengue Virus
Significantly elevated levels of vascular endothelial growth factor
alpha (VEGF-α), TNF-α and IL-6. Immune suppression
[114]
3)
Influenza Virus
Infection
Increased production of IL-1α, IL-6, and TNF-α. Increased infiltration of
immune cells inside pulmonary parenchyma. Hyper activation of
inflammatory pathway, higher levels of Ferritin and C-Reactive
Protein
[132, 133,
158]
4)
Bacteria Induced CS
Increased levels of TNF-α, interluekins chemokines and G-CSF,
[51, 185.
190]
5)
SARS-CoV-1
Elevated levels of IL-8, IL-1β, TNF-α, and IL-6 in alveolar lavage
and blood plasma and significant Lymphopenia, higher levels of
Ferritin and C-Reactive Protein
[8, 204]
6)
MERS-CoV-1
Significantly higher levels of procalcitonin, and IL-6 being a
prominent indicator of CS. The main differentiating factors
includes absence of hyperferritinemia and absence of any
significant elevation in C reactive protein levels
[51, 133-
140, 202]
7)
Macrophage Activation
Syndrome
Ferritin levels above the threshold level of 10,000 ng/mL.
Similarly the markers like neopterin, soluble CD163, and soluble
CD25 were found to be elevated.
[74, 75,
121]
8)
SARS-CoV-2
i. Clinical signs suggestive of COVID-19 and positive for
RT-PCR for SARS- CoV-2.
ii. GGO in high resolution CT Scan
iii. BUN: Creatinine ratio greater than 29
iv. ALT, AST, D-Dimers, LDH and Troponin-I levels above
the threshold levels.
v. Neutrophil Abs above >11.4 K/mm3,
vi. ferritin and C Reactive protein levels above threshold
levels of >250 ng/mL and >4.6 mg/dL respectively.
[13, 46, 19,
187-189,
201]
Journal Pre-proof
S.no
Diagnostic Criterion of cytokine storm in COVID-19 patients
References
1)
Serum albumin levels less than 2.87 mg/mL, blood lymphocyte count less than 10.2% and
absolute neutrophil count more than 11.4 × 103/mL
[46, 189,
181]
2)
Significantly higher values of SPO2/FiO2; Neutrophil/Lymphocyte and cytokines/chemokines
are more predictive for COVID-19-CS.
[13, 188,
196]
3)
D-dimer concentrations above 1.5 µg/mL and concurrent incidence of thrombi-embolism is
highly predictive of COVID-19 CS. These parameters were found to have high sensitivity and
high specificity.
[31-34, 198]
4)
Sepsis-induced coagulopathy score of significantly higher with values being more or equal to
4 with concurrently elevated levels of D-Dimer
[34, 187]
5)
ALT levels more than 60 IU/L, AST levels more than 87 IU/L, D-Dimer levels more than
4930 ng/mL, LDH levels more than 416 U/L and levels of troponin-I more than 1.09 ng/mL
[46, 185]
6)
Ground glass appearance, thickening of alveolar walls, presence of pleural fluid and
collapsing of alveoli
[20, 21]
7)
Screening for hyper-inflammatory markers and H Score
[1]
8)
D-Dimer levels significantly elevated with fibrinogen levels above 2.0 g/L
[33, 182]
9)
Anion gap less than 6.8 mmol/L, significantly higher levels of sodium, potassium and blood
urea nitrogen. Levels of ferritin >250 ng/mL and C-Reactive protein >4.6 mg/dL
[46, 186]
10)
Significant increase in levels of D-Dimer and prothrombin time greater than 3.0 s and aPTT
>5 seconds
[33-35]
11)
Post-mortem findings of spleen atrophy, visceral haemorrhages and hepatomegaly in COVID-
19 patients
[33, 62,184]
12)
Severe lymphopenia with pronounced reduction in CD4+ and CD8+ T cell levels with up
regulation of exhaustion markers like NKG2A
[31]
Journal Pre-proof
Pro-
inflammatory
cytokine
Role in cytokine storm
Reference
IL-6
Causes activation of JAK/STAT signalling pathway which results in hyper-
activation of inflammatory cum immune pathways.
Causes transformation and maturation of CD8+ T and B cells
[55, 56, 202]
IFN-γ
Activates JAK/STAT pathway and causes proliferation and sensitization of
macrophage, NK, and T cell.
[57-59, 198]
TNFα
TNFα acts as activator of NF-κB which causes up-regulation of the inflammatory
and apoptotic genes in immune cells
[60-65, 197]
IL-1β
NLRP3 inflammasome causes cleavage of IL-1βprecursor to active form of IL-1β
which provides positive feedback for NF-κB activation which initiates the
inflammatory cascade.
[66, 190-193,
201]
IL-2
Significantly lower levels of IL-2 have been observed in other related
coronaviruses.
Lymphopenia observed in COVID-19-CS have been attributed to lower levels of IL-
2
[40, 192]
IL-7
Significantly higher levels of IL-7 have been attributed to feedback mechanism to
Lymphopenia
[40,200]
IL-10
IL-10 acts as potent immune regulator and is produced by CD8+ T cells and
Tregs. It regulated immune function by autocrine and paracrine manner by acting
on innate immune system.
[40, 48, 80 191,
192 199]
IL-12
Acts as an important immune regulator and acts and causes proliferation of Th1
and Th17 cells and cause activation of diverse set of immune cum inflammatory
cells, henceforth contributes in CS.
[7, 40, 80 187]
IL-17
Causes recruitment of immune cells to site of inflammation and promotes
expression of pro-inflammatory genes via pleiotropic effect. These cytokines have
been reported to cause tissue modelling.
[40, 198]
GM-CSF
Under normal circumstances GM-CSF maintain integrity of alveolar epithelium
and provide local anti-bacterial micro-environment. Under hyper inflammation
GM-CSF causes myelopoiesis and recruits myeloid cells to site of
infection/injury, henceforth maintains sustained inflammatory process.
[128, 132, 195]
Journal Pre-proof
Interventions
Role
Benefits
Drawbacks
References
Hydroxychloroquine/Chloroqui
ne
(n=166)
Inhibits the production of IL-6
and TNF
Reduce viral load and infection
duration
Retinopathy, myopathy, neuromyopathy,
cardiopathy, and arrhythmia
[63]
IL-6 Receptor Inhibitors
(tocilizumab)
(n=21)
(n=3924)
Blocks IL-6 receptors and hence
prevents interaction of IL-6 with
its cellular receptors
Improved clinical outcome
Significantly reduced need for
invasive ventilation
Decreased hospitalization
Significantly reduced mortality
Not well known
[207]
IL-1 β Blocker
anakinra
(N=22)
These drugs bind with IL-1 and
causes competitive inhibition of
the IL-1β
Decreased serum levels of
Ferritin, C reactive protein
Improved clinical score of
patients
Not well known
[208]
IFN-λ blocker
Emapalumab
(trail has been terminated)
These activates anti-viral genes
in epithelial cells
Causes stimulation immune
system without causing over
activation of immune response
Treatment was not able to reduce mortality and at
later stages of disease drug was in-effective
209
IL-6 inhibitors (siltuximab)
(n=30)
Inhibits IL-6 and hence its
interaction with IL-6 receptor
Improvement in clinical outcome
of more than 50% of patients
Not well known
[210]
IL-1 Family Antagonists
Caused immune-modulation
Significantly reduced mortality
during hospital stay of 28 days
Needs to be evaluated through clinical trials and
animal studies
[211]
Corticosteroids
Retrospective study (n=401)
Suppress the host inflammatory
and immune reaction
Reduces mortality and stay in
hospital by 3–5 days
Lower incidence of secondary
infections
impaired viral clearance in non-ICU patients
avascular necrosis, diabetes, and psychosis
[212]
TNF-blockers
infliximab
(n=56)
Ameliorates T cell response and
causes restoration of lung injury
Significantly improved survival of
patients with systemic sepsis.
Limited number of patients have been observed
but study need to be observed in large clinical trial
[7]
Journal Pre-proof
Sepsivac (Mycobacterium
Indicus Parnii)
(n=)
Acts as immune modular and
keeps effective check on
activation of inflammatory
pathways
Reduced days of hospitalization
and need for mechanical
ventilation
No side effects were observed except increase in
levels of ALT and AST.
[213, 214]
Tocilizumab
(n=122)
Blocks IL-6 signaling pathway to
prevent cytokine storm.
Was found to be effective in
patients with bilateral lung
lesions
Improves survival outcome
Decreased days under
mechanical ventilation
Severe infections, neutropenia, hepatic damage,
and thrombocytopenia
[209]
GM-CSF inhibition
Sargramostim/ Molgramostim
(n=13)
Cause modulation of immune
system
Rapid clinical improvement,
restoration of blood biochemistry
to normal and pyrexia resolution
Not well known
[210]
MSC
Prevents the aberrant
stimulation of macrophages and
T cells and the release of
proinflammatory cytokines
Decreases mortality
Not well known
[22]
Anakinra
Inhibits IL-1α and IL-1β
Improves respiratory function
and increases patient survival
rate
Increases bacterial infection risk
[76]
Intravenous immunoglobulins
(n=99)
Block Fc receptors and exert
different immunomodulatory
effects
Reduces severity of inflammation
immune substitution and
immunomodulation
Thrombosis, Lung injury
[211]
Ulinastatin
Decreases IL-6, IFNα and TNF
while increases IL-10 levels
Shield the vascular endothelium
by preventing inflammatory
mediators from being produced
and released
Femoral head necrosis
[207]
JAK/STAT inhibitors
(N=56)
Inhibit inflammatory cytokines
and decrease viral entry into
cells
Improve clinical symptoms and
respiratory parameters
Inhibiting the production of IFNα which is
important for fighting viruses
[206]
Journal Pre-proof
NF-κB pathway blockers
Preclinical studies have reported
that blocking NF-κB causes
immune modulation
Preclinical studies support its
use in randomized clinical trail
Not well known
212
Journal Pre-proof
Journal Pre-proof
Journal Pre-proof
Journal Pre-proof
Journal Pre-proof
Highlights
• Cytokine storm is the outcome of respiratory illnesses such as MERS, SARS, and COVID-
19.
• Patients with cytokine storms exhibit mild to severe clinical manifestations.
• Immune pathways such as JAK/STAT, mTOR, ERK, and TRAF/NF-κB are stimulated in
respiratory illness.
• Cytokine storm can be early controlled using immunomodulators and cytokine antagonists.
Journal Pre-proof
Declaration of interests
☒ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests:
Journal Pre-proof
