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Mycobacterium leprae (M. leprae) infection gives rise to the immunologically and histopathologically classified spectrum of leprosy. At present several tools for the stratification of patients are based on acquired immunity markers. However, the role of innate immunity, particularly the complement system, is largely unexplored. The present retrospe...
Citations
... Of the immune proteins specifically, the leprosarium samples contained inter-alpha-trypsin inhibitor heavy chain H4; alpha-1-antitrypsin; histidine-rich glycoprotein; alpha-2-macroglobulin; amyloid-beta A4; arginase-1; C-reactive protein; cathepsin D; clusterin; elF-2-alpha kinase; haptoglobin; heat shock protein beta-1 and HSP 90-beta; osteopontin; thrombospondin; six complement system proteins (C3, C4-A, C8 beta, C8 gamma, factor B); three fibrinogens (alpha, beta, and gamma chains); and 10 immunoglobulins: IgA heavy chain constant region 1, IgG heavy constant 2 and 3, Ig kappa chain constant region, Ig kappa light chain, Ig kappa variable (1-27, 1-6, and 2D-20), and Ig lambda constant 2 and 7. Most of the immune proteins were recovered from the two specific individuals (ZH1114, ZH1117). They may have been suffering from active leprosy infection with a type 2 immune reaction (erythema nodosum leprosum), painful inflammation seen mostly in individuals who have lepromatous leprosy 41,54,57,71,72 (Figures 5 and 6; Table S5E). ...
... While we found that C9 was equally present in individuals from within and outside of the leprosarium, we did see increased PSMs of C3 and C4A in two individuals (ZH1114, ZH1117); as well as complement factor B and H, as well as IHRP in one of the same individuals (ZH1117). Proteins of the complement system are highly linked to the innate response to leprosy, but also to many other unrelated infections, 54,72 and includes the fusion of multiple complement protein fractions to form membrane attack complexes that defend against the pathogen. However, the complement response can often become ''overactivated'' during leprosy infection, resulting in extensive nerve and skin damage in the patient. ...
This study investigates the efficacy of proteomic analysis of human remains to identify active infections in the past through the detection of pathogens and the host response to infection. We advance leprosy as a case study due to the sequestering of sufferers in leprosaria and the suggestive skeletal lesions that can result from the disease. Here we present a sequential enzyme extraction protocol, using trypsin followed by ProAlanase, to reduce the abundance of collagen peptides and in so doing increase the detection of non-collagenous proteins. Through our study of five individuals from an 11th to 18th century leprosarium, as well as four from a contemporaneous non-leprosy associated cemetery in Barcelona, we show that samples from 2 out of 5 leprosarium individuals extracted with the sequential digestion methodology contain numerous host immune proteins associated with modern leprosy. In contrast, individuals from the non-leprosy associated cemetery and all samples extracted with a trypsin-only protocol did not. Through this study, we advance a palaeoproteomic methodology to gain insights into the health of archaeological individuals and take a step toward a proteomics-based method to study immune responses in past populations.
... In leprosy, components of the complement system deposited on the surface of M. leprae are recognized by CR1 and CR3 receptors and subsequently phagocytized by human monocytes [7]. In addition, serum levels of terminal complement components have been associated with the occurrence of leprosy reaction in Bangladeshi patients [8]. Accordingly, a Brazilian study demonstrated that serum PTX3 levels were higher in multibacillary patients before the development of erythema nodosum leprosum and that thalidomide treatment reduced PTX3 levels [9]. ...
Background
Pentraxin 3 (PTX3) is a soluble pattern recognition receptor that plays a crucial role in modulating the inflammatory response and activating the complement system. Additionally, plasma PTX3 has emerged as a potential biomarker for various infectious diseases. The aim of this study was to evaluate the association of PTX3 gene polymorphisms and PTX3 plasma levels with susceptibility to leprosy and clinical characteristics.
Methods
Patients with leprosy from a hyperendemic area in the Northeast Region of Brazil were included. Healthy household contacts and healthy blood donors from the same geographical area were recruited as a control group. The rs1840680 and rs2305619 polymorphisms of PTX3 were determined by real-time PCR. Plasma levels of PTX3 were determined by ELISA.
Results
A total of 512 individuals were included. Of these, 273 were patients diagnosed with leprosy; 53 were household contacts, and 186 were healthy blood donors. No association was observed between PTX3 polymorphisms and susceptibility to leprosy or development of leprosy reaction or physical disability. On the other hand, plasma levels of PTX3 were significantly higher in patients with leprosy when compared to household contacts (p = 0.003) or blood donors (p = 0.04). It was also observed that PTX3 levels drop significantly after multidrug therapy (p < 0.0001).
Conclusions
Our results suggest that PTX3 may play an important role in the pathogenesis of leprosy and point to the potential use of this molecule as an infection marker.
... TLRs are cellular receptors present mainly in antigen-presenting cells (APCs), which are responsible for recognizing different types of antigens. The TLR2-TLR1, TLR2, and TLR4 were identified as the main Toll-like receptors able to recognize M. leprae antigens [51,52], although recently (2021) TLR9 demonstrated to also sensing M. leprae DNA [53]. In fact, phagocytes from the nasal mucosa (MCs and DCs) are known to be the first cells from immune system that recognize M. leprae by TLRs [48,54], once the pathogen is dispersed mainly through the upper airways and notably through the nose. ...
... In addition to APPs, components of the complement system (e.g., C3b, C4b, and iC3b) and immunoglobulins opsonize molecules to promote phagocytosis (114). Notably, terminal complement complex (TCC) and iC3b of the complement system are valuable for the stratification of leprosy patients with or without T1R (115). ...
Leprosy reactions are acute inflammatory episodes that complicate the course of a Mycobacterium leprae infection and are the major cause of leprosy-associated pathology. Two types of leprosy reactions with relatively distinct pathogenesis and clinical features can occur: type 1 reaction, also known as reversal reaction, and type 2 reaction, also known as erythema nodosum leprosum. These acute nerve-destructive immune exacerbations often cause irreversible disabilities and deformities, especially when diagnosis is delayed. However, there is no diagnostic test to detect or predict leprosy reactions before the onset of clinical symptoms. Identification of biomarkers for leprosy reactions, which impede the development of symptoms or correlate with early-onset, will allow precise diagnosis and timely interventions to greatly improve the patients' quality of life. Here, we review the progress of research aimed at identifying biomarkers for leprosy reactions, including its correlation with not only immunity but also genetics, transcripts, and metabolites, providing an understanding of the immune dysfunction and inflammation that underly the pathogenesis of leprosy reactions. Nevertheless, no biomarkers that can reliably predict the subsequent occurrence of leprosy reactions from non-reactional patients and distinguish type I reaction from type II have yet been found.
... In mycobacteria, MBL has been shown to bind to lipoarabinomannan (LAM) from Mycobacterium avium [36] and mannosylated lipoarabinomannan (ManLAM) from several others, e.g., M. tuberculosis, M. bovis, M. kansasii, Mycobacterium gordonae and Mycobacterium smegmatis [40]. The persistence of M. leprae LAM in mice contributes to the deposition of membrane attack complex (MAC), resulting in myelin loss and axonal damage [41]. Conversely, the inhibition of MAC provides neuroprotection in response to M. leprae infection [41]. ...
... The persistence of M. leprae LAM in mice contributes to the deposition of membrane attack complex (MAC), resulting in myelin loss and axonal damage [41]. Conversely, the inhibition of MAC provides neuroprotection in response to M. leprae infection [41]. Multi-drug therapy for the treatment of M. leprae was believed to release dead bacilli, and Mycobacterium. ...
... Multi-drug therapy for the treatment of M. leprae was believed to release dead bacilli, and Mycobacterium. leprae LAM can sustain persistent complement activation, resulting in chronic inflammation [41,42]. ...
The complement system orchestrates a multi-faceted immune response to the invading pathogen, Mycobacterium tuberculosis. Macrophages engulf the mycobacterial bacilli through bacterial cell surface proteins or secrete proteins, which activate the complement pathway. The classical pathway is activated by C1q, which binds to antibody antigen complexes. While the alternative pathway is constitutively active and regulated by properdin, the direct interaction of properdin is capable of complement activation. The lectin-binding pathway is activated in response to bacterial cell surface carbohydrates such as mannose, fucose, and N-acetyl-D-glucosamine. All three pathways contribute to mounting an immune response for the clearance of mycobacteria. However, the bacilli can reside, persist, and evade clearance by the immune system once inside the macrophages using a number of mechanisms. The immune system can compartmentalise the infection into a gran-ulomatous structure, which contains heterogenous sub-populations of M. tuberculosis. The granu-loma consists of many types of immune cells, which aim to clear and contain the infection whilst sacrificing the affected host tissue. The full extent of the involvement of the complement system during infection with M. tuberculosis is not fully understood. Therefore, we reviewed the available literature on M. tuberculosis and other mycobacterial literature to understand the contribution of the complement system during infection.
... Delays in diagnosis of reactions directly translate into negative clinical outcomes, as associated neuropathy not properly diagnosed or treated within the first 6 months of symptoms will likely become permanent 20 alongside the disabilities it may later initiate via recurrent ulcers and other related pathologies 21 . Despite recent scientific progress with respect to complement 22,23 and serum-proteins, particularly CXCL10 (IP-10), as biomarkers associated with onset of reactions [15][16][17][24][25][26] , discovery of accurate, clinically useful prognostic biomarkers remains elusive, leaving early diagnosis of reactions a currently unmet need. ...
Early diagnosis of leprosy is challenging, particularly its inflammatory reactions, the major cause of irreversible neuropathy in leprosy. Current diagnostics cannot identify which patients are at risk of developing reactions. This study assessed blood RNA expression levels as potential biomarkers for leprosy. Prospective cohorts of newly diagnosed leprosy patients, including reactions, and healthy controls were recruited in Bangladesh, Brazil, Ethiopia and Nepal. RNA expression in 1,090 whole blood samples was determined for 103 target genes for innate and adaptive immune profiling by dual color Reverse-Transcription Multiplex Ligation-dependent Probe Amplification (dcRT-MLPA) followed by cluster analysis. We identified transcriptomic biomarkers associated with leprosy disease, different leprosy phenotypes as well as high exposure to Mycobacterium leprae which respectively allow improved diagnosis and classification of leprosy patients and detection of infection. Importantly, a transcriptomic signature of risk for reversal reactions consisting of five genes (CCL2, CD8A, IL2, IL15 and MARCO) was identified based on cross-sectional comparison of RNA expression. In addition, intra-individual longitudinal analyses of leprosy patients before, during and after treatment of reversal reactions, indicated that several IFN-induced genes increased significantly at onset of reaction whereas IL15 decreased. This multi-site study, situated in four leprosy endemic areas, demonstrates the potential of host transcriptomic biomarkers as correlates of risk for leprosy. Importantly, a prospective five-gene signature for reversal reactions could predict reversal reactions at least 2 weeks before onset. Thus, transcriptomic biomarkers provide promise for early detection of these acute inflammatory episodes and thereby help prevent permanent neuropathy and disability in leprosy patients.
... Other molecules belonging to the complement system were also found to contribute to a risk signature as systemic levels of complement factors such as terminal complement complex (TCC) and iC3b were valuable for stratification of patients from Bangladesh and Ethiopia into those with and without T1R [72]. ...
Leprosy is still a considerable health threat in pockets of several low and middle income countries worldwide where intense transmission is witnessed, and often results in irreversible disabilities and deformities due to delayed- or misdiagnosis. Early detection of leprosy represents a substantial hurdle in present-day leprosy health care. The dearth of timely diagnosis has, however, particularly severe consequences in the case of inflammatory episodes, designated leprosy reactions, which represent the major cause of leprosy-associated irreversible neuropathy.
There is currently no accurate, routine diagnostic test to reliably detect leprosy reactions, or to predict which patients will develop these immunological exacerbations. Identification of host biomarkers for leprosy reactions, particularly if correlating with early onset prior to development of clinical symptoms, will allow timely interventions that contribute to decreased morbidity. Development of a point-of-care (POC) test based on such correlates would be a definite game changer in leprosy health care.
In this review, proteomic-, transcriptomic and metabolomic research strategies aiming at identification of host biomarker-based correlates of leprosy reactions are discussed, next to external factors associated with occurrence of these episodes. The vast diversity in research strategies combined with the variability in patient- and control cohorts argues for harmonisation of biomarker discovery studies with geographically overarching study sites. This will improve identification of specific correlates associated with risk of these damaging inflammatory episodes in leprosy and subsequent application to rapid field tests.
... These proteins are related but not directly involved in the leprosum clot formation, because high levels of both proteins were also observed in leprosy patients sera weeks prior to leprosum clot occurrence. It was already demonstrated that complement activation products are highly abundant in leprosy reactional episodes, and their presence in the leprosum clot is probably circumstantial [41]. IHRP, which is also increased in patient's sera and blood clot, belongs to the inter-alphatrypsin inhibitor family of acute phase proteins, comprising the common light chain bikunin. ...
Background
Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae infection. In 2016, more than 200,000 new cases of leprosy were detected around the world, representing the most frequent cause of infectious irreversible deformities and disabilities.
Principal findings
In the present work, we demonstrate a consistent procoagulant profile on 40 reactional and non-reactional multibacillary leprosy patients. A retrospective analysis in search of signs of coagulation abnormalities among 638 leprosy patients identified 35 leprosy patients (5.48%) which displayed a characteristic lipid-like clot formed between blood clot and serum during serum harvesting, herein named ‘leprosum clot’. Most of these patients (n = 16, 45.7%) belonged to the lepromatous leprosy pole of the disease. In addition, formation of the leprosum clot was directly correlated with increased plasma levels of soluble tissue factor and von Willebrand factor. High performance thin layer chromatography demonstrated a high content of neutral lipids in the leprosum clot, and proteomic analysis demonstrated that the leprosum clot presented in these patients is highly enriched in fibrin. Remarkably, differential 2D-proteomics analysis between leprosum clots and control clots identified two proteins present only in leprosy patients clots: complement component 3 and 4 and inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP). In agreement with those observations we demonstrated that M. leprae induces hepatocytes release of IHRP in vitro.
Conclusions
We demonstrated that leprosy MB patients develop a procoagulant status due to high levels of plasmatic fibrinogen, anti-cardiolipin antibodies, von Willebrand factor and soluble tissue factor. We propose that some of these components, fibrinogen for example, presents potential as predictive biomarkers of leprosy reactions, generating tools for earlier diagnosis and treatment of these events.
... The complement system is crucial for the opsonisation and subsequent killing of bacteria. Previous studies have indicated an important role for complement in leprosy, showing increased levels of complement components by serological and pathological studies [5][6][7][8][9][10][11]. Another study showed deposits of the MAC in cutaneous sensory nerves of leprosy patients, suggesting a possible role for MAC in leprosy pathology [10,12]. ...
Mycobacterium leprae (M. leprae) infection causes nerve damage and the condition worsens often during and long after treatment. Clearance of bacterial antigens including lipoarabinomannan (LAM) during and after treatment in leprosy patients is slow. We previously demonstrated that M. leprae LAM damages peripheral nerves by in situ generation of the membrane attack complex (MAC). Investigating the role of complement activation in skin lesions of leprosy patients might provide insight into the dynamics of in situ immune reactivity and the destructive pathology of M. leprae. In this study, we analyzed in skin lesions of leprosy patients, whether M. leprae antigen LAM deposition correlates with the deposition of complement activation products MAC and C3d on nerves and cells in the surrounding tissue. Skin biopsies of paucibacillary (n = 7), multibacillary leprosy patients (n = 7), and patients with erythema nodosum leprosum (ENL) (n = 6) or reversal reaction (RR) (n = 4) and controls (n = 5) were analyzed. The percentage of C3d, MAC and LAM deposition was significantly higher in the skin biopsies of multibacillary compared to paucibacillary patients (p = <0.05, p = <0.001 and p = <0.001 respectively), with a significant association between LAM and C3d or MAC in the skin biopsies of leprosy patients (r = 0.9578, p< 0.0001 and r = 0.8585, p<0.0001 respectively). In skin lesions of multibacillary patients, MAC deposition was found on axons and co-localizing with LAM. In skin lesions of paucibacillary patients, we found C3d positive T-cells in and surrounding granulomas, but hardly any MAC deposition. In addition, MAC immunoreactivity was increased in both ENL and RR skin lesions compared to non-reactional leprosy patients (p = <0.01 and p = <0.01 respectively). The present findings demonstrate that complement is deposited in skin lesions of leprosy patients, suggesting that inflammation driven by complement activation might contribute to nerve damage in the lesions of these patients. This should be regarded as an important factor in M. leprae nerve damage pathology.
Leprosy is a chronic granulomatous infectious and disabling disease caused by two mycobacteria, Mycobacterium leprae and Mycobacterium lepromatosis. Acute inflammatory responses, known as leprosy reactions, are significant contributors to disabilities. Three types of leprosy reactions have been identified based on excessive cytokine release (e.g. type 1) or the accumulation of immune complexes in tissues inducing multiorgan damage (e.g. types 2 and 3). The type of leprosy reaction has implications on treatment and management strategies, yet are not well understood by health workers caring for leprosy patients. We attempt to describe the immunologic mechanisms behind the different leprosy reactions and the rationale for tailoring clinical treatment and management to the particular type of leprosy reaction based on the underlying immunologic situation.
