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Immunohistochemical staining of carotid plaques for TLR7 and cell markers. (A, B) TLR7 staining in a T cell-rich area. (C) CD3-positive staining in consecutive slides. (D) CD8 staining in consecutive slides. (E, F) TLR7. (G) CD68. (H) CD163. Positive cells are stained with Vulcan fast red, and the nuclei are stained blue. Scale bars: (A, E) 100 mm. (B-D, F-H) 10 mm.
Source publication
Aims:
Processes in the development of atherosclerotic lesions can lead to plaque rupture or erosion, which can in turn elicit myocardial infarction or ischaemic stroke. The aims of this study were to determine whether Toll-like receptor 7 (TLR7) gene expression levels influence patient outcome and to explore the mechanisms linked to TLR7 expressio...
Contexts in source publication
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... we measured TLR7 levels by immunohistochemistry. TLR7 was expressed in all plaques (Figure 2A, B, E, and F). The staining pattern indi- cated that TLR7 was expressed primarily on cells of haematopoietic ori- gin. Consecutive sections that were stained with T cell (Figure 2A and B) and macrophage ( Figure 2C and D) markers showed that TLR7 co- localized with the areas that were infiltrated by these cell ...
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... we measured TLR7 levels by immunohistochemistry. TLR7 was expressed in all plaques (Figure 2A, B, E, and F). The staining pattern indi- cated that TLR7 was expressed primarily on cells of haematopoietic ori- gin. Consecutive sections that were stained with T cell (Figure 2A and B) and macrophage ( Figure 2C and D) markers showed that TLR7 co- localized with the areas that were infiltrated by these cell ...
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... we measured TLR7 levels by immunohistochemistry. TLR7 was expressed in all plaques (Figure 2A, B, E, and F). The staining pattern indi- cated that TLR7 was expressed primarily on cells of haematopoietic ori- gin. Consecutive sections that were stained with T cell (Figure 2A and B) and macrophage ( Figure 2C and D) markers showed that TLR7 co- localized with the areas that were infiltrated by these cell ...
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... has been used in other studies because it is a TLR7 specific ligand. We sought to investigate the activation level for imiquimod in comparison with other TLR7 ligands. The in vitro system of TLR7- transformed HEK cells was used, and two other ligands, CL307 and R848, were also tested. The comparisons showed a more moderate re- sponse to imiquimod than to CL307 and R848 (see Supplementary ma terial online, Figure ...
Citations
... For example, TLR7 mutations are associated with the symptom severity of COVID-19 (93)(94)(95). TLR7 has also been implicated in the progression of Parkinson's disease (96), Alzheimer's disease (15,97,98), and autoimmune diseases such as systemic lupus erythematosus (99) and atherosclerosis (100,101). Although the growing evidence of TLR7 involvement in the pathogenesis of noninfectious diseases highlights the need for a better understanding of endogenous ssRNA ligands of immune receptors, their exploration and characterization are still at an initial stage, and we are just beginning to appreciate the previously hidden classes of sncRNAs not detected by standard RNA-seq methods. ...
Toll-like receptors (TLRs) are crucial components of the innate immune system. Endosomal TLR7 recognizes single-stranded RNAs, yet its endogenous ssRNA ligands are not fully understood. We previously showed that extracellular (ex-) 5′-half molecules of tRNA HisGUG (the 5′-tRNA HisGUG half) in extracellular vesicles (EVs) of human macrophages activate TLR7 when delivered into endosomes of recipient macrophages. Here, we fully explored immunostimulatory ex-5′-tRNA half molecules and identified the 5′-tRNA ValCAC/AAC half, the most abundant tRNA-derived RNA in macrophage EVs, as another 5′-tRNA half molecule with strong TLR7 activation capacity. Levels of the ex-5′-tRNA ValCAC/AAC half were highly up-regulated in macrophage EVs upon exposure to lipopolysaccharide and in the plasma of patients infected with Mycobacterium tuberculosis . The 5′-tRNA ValCAC/AAC half-mediated activation of TLR7 effectively eradicated bacteria infected in macrophages. Mutation analyses of the 5′-tRNA ValCAC/AAC half identified the terminal GUUU sequence as a determinant for TLR7 activation. We confirmed that GUUU is the optimal ratio of guanosine and uridine for TLR7 activation; microRNAs or other RNAs with the terminal GUUU motif can indeed stimulate TLR7, establishing the motif as a universal signature for TLR7 activation. These results advance our understanding of endogenous ssRNA ligands of TLR7 and offer insights into diverse TLR7-involved pathologies and their therapeutic strategies.
... TREM2 promotes the formation of foam cells derived from smooth muscle cells and macrophages through regulating the expression of scavenger receptor CD36, thereby exacerbating the development of atherosclerosis [20]. TLR7 is abundantly expressed in human atherosclerotic plaques and ligation can trigger the secretion of pro-inflammatory and anti-inflammatory cytokines [21]. A previous study found that compared patients with asymptomatic disease, T cells and macrophages in carotid plaques of patients with clinically symptomatic disease have different characteristics [22]. ...
Atherosclerosis is a chronic immuno-inflammatory disease, however, the immune landscape and regulatory mechanisms have not been clear. We detected seven principal immune cell clusters with distinct phenotypic and spatial characteristics using single-cell RNA-sequencing of aortic immune cells from patients with acute coronary syndrome and stable angina pectoris. Then we acquired 265 differentially expressed immune-related genes and the high scores were mainly found in T cells and monocytes, which were differentially regulated in atherosclerotic coronary plaques. The CCL signaling pathway was the most relevant pattern in the T cells and CCL5-CCR1 and CCL5-CCR5 ligand-receptor pairs played a vital role in the CCL signaling pathway. Further comparative analysis indicated MCH-I signaling was the most relevant pattern in the T cells and HLA ligand-related ligand-receptor pairs played a vital role. Functional analysis of the single-cell and bulk transcriptomics pointed to multiple pathways, such as antigen presentation and immune response. Nineteen common differentially expressed immune-related genes were found in both immune cells and the human peripheral blood mononuclear cells. Nine common differentially expressed transcription factors were differentially expressed in both T cell and monocyte clusters from the coronary plaques and human peripheral blood mononuclear cells and the network demonstrated that CEBPB might play an essential role in the transcriptional regulation of atherosclerosis as a hub transcription factor. The definition of immune cell diversity and heterogeneity by single-cell level analysis of aortic immune cell subsets not only unveils cell-type-specific pathways and new immune mechanisms but also discovers the functional correlation of immune cells in human atherosclerosis. Our findings provide great promise for the discovery of novel molecular mechanisms and precise therapeutic targets for atherosclerosis.
... Apolipoprotein B, the cholesterol-carrying component of LDL, is known to have a carcinogenic effect on the retention and accumulation of subendothelial lipids in arteries 37 . Glykeria K et al. found that patients with higher levels of TLR7 transcripts presented with a lower risk of major cardiovascular and cerebrovascular events in the follow-up period after carotid endarterectomy, and carotid plaque immunohistochemistry showed that TLR7 was expressed in all plaques by T cells, macrophages and endothelial cells in capillaries 24 . Similar to TLR7, SAMHD1 38 initiates innate immunity mainly by binding endogenous ligands, including viral-derived ssRNA and mononucleotides 39 . ...
RNA-binding proteins (RBPs) are involved in the regulation of RNA splicing, stability, and localization. How RBPs control the development of atherosclerosis, is not fully understood. To explore the relevant RNA-binding proteins (RBPs) and alternative splicing events (ASEs) in atherosclerosis. We made a comprehensive work to integrate analyses of differentially expressed genes, including differential RBPs, and variable splicing characteristics related to different stages of atherosclerosis in dataset GSE104140. A total of 3712 differentially expressed genes (DEGs) were identified, including 2921 upregulated genes and 791 downregulated genes. Further analysis screened out 54 RBP genes, and 434 AS genes overlapped DEGs. We selected high expression ten RBP genes (SAMHD1, DDX60 L, TLR7, RBM47, MYEF2, RNASE6, PARP12, APOBEC3G, SMAD9, and RNASE1) for co-expression analysis. Meanwhile, we found seven regulated alternative splicing genes (RASGs) (ABI1, FXR1, CHID1, PLEC, PRKACB, BNIP2, PPP3CB) that could be regulated by RBPs. The co-expression network was used to further elucidate the regulatory and interaction relationship between RBPs and AS genes. Apoptotic process and innate immune response, revealed by the functional enrichment analysis of RASGs regulated by RBPs were closely related to atherosclerosis. In addition, 26 of the 344 alternative splicing genes regulated by the above 10 RBPs were transcription factors (TFs), We selected high expression nine TFs (TFDP1, RBBP7, STAT2, CREB5, ERG, ELF1, HMGN3, BCLAF1, and ZEB2) for co-expression analysis. The target genes of these TFs were mainly enriched in inflammatory and immune response pathways that were associated with atherosclerosis. indicating that AS abnormalities of these TFs may have a function in atherosclerosis. Furthermore, the expression of differentially expressed RBPs and the alternative splicing events of AS genes was validated by qRT-PCR in umbilical vein endothelial cells (HUVEC). The results showed that RBM47 were remarkedly difference in HUVEC treated with ox-LDL and the splicing ratio of AS in BCLAF1which is regulated by RBM47 significantly changed. In conclusion, the differentially expressed RBPs identified in our analysis may play important roles in the development of atherosclerosis by regulating the AS of these TF genes.
... Atherosclerosis mainly occurs in large and medium-sized arteries of the systemic circulatory system [17]. The pathological process is very long, causing stroke, myocardial infarction, and even sudden death [18]. ...
Background
Atherosclerosis is the pathological basis of cardio-cerebrovascular diseases. Oxidized low-density lipoprotein (ox-LDL) is an important risk factor for atherosclerosis. Ox-LDL leads to endothelial cell (EC) damage and dysfunction through various processes and promotes the occurrence and deterioration of atherosclerosis. High mobility group box-1 (HMGB1) is a protein associated with cellular damage. In the present study, the effect of HMGB1 on ox-LDL-induced EC damage was determined and the underlying mechanism explored.
Materials and methods
Human umbilical vein ECs (HUVECs) were exposed to ox-LDL to induce endothelial damage and changes in HMGB1 expression level were detected using western blotting analysis and reverse transcription-quantitative PCR. To observe the effect of HMGB1 on ox-LDL-induced damage, the HMGB1 expression was downregulated with siRNA, and cell viability, cytotoxicity, and apoptosis rate were assessed. HUVECs were pretreated with LY294002, an inhibitor of the PI3K/Akt pathway, to determine whether the effect of HMGB1 on damage is via the PI3K-Akt pathway.
Results
The results showed that ox-LDL can upregulate HMGB1 expression in HUVECs and downregulation of HMGB1 expression can prevent ox-LDL-induced damage in HUVECs. Furthermore, the effect of HMGB1 on ox-LDL-induced damage could be promoted by inhibiting the PI3K/Akt signaling pathway.
Conclusion
The results indicate HMGB1 may be a promising research target to alleviate ox-LDL-induced EC damage.
... В исследовании Karadimou G. и соавт. [6] представлено, что при инфильтрации зоны атеросклеротического поражения Т-лимфоцитами, макрофага-ми может быть ОИМ или ишемический инсульт. С.Г. ...
We examined 23 patients aged 40 to 65 years (mean age 54.526.72) with a diagnosis of acute coronary syndrome (ACS) at admission, who underwent emergency or delayed coronary stenting a day later. All patients had arterial hypertension as a concomitant disease. Upon additional examination, blood troponin levels were determined, ECG was performed in the time dynamics. Acute myocardial infarction with ST elevation was diagnosed in 7 patients, infarction without ST elevation, in 6 patients, the unstable angina rest, in the rest of this group (Grace risk from 75 to 150 points, on average, 107.727.16 points). To assess the immune status, especially, lymphocyte populations and subsets we used standardized techniques, i.e., flow cytometric assays with Navios cytofluorimeter (Beckman Coulter, USA). The following subpopulations were determined: CD45+ (panleukocyte marker for gating lymphocytes), CD45+, CD3+ (T cells), CD45+, CD3+, CD4+ (helper inducers), CD45+, CD3+, CD8+ (cytotoxic T cells), CD45+, CD3+CD16+, CD56+ (TNK cells) CD45+, CD3-, CD16+, CD56+ (natural killer cells), CD45+, CD3-, CD19+CD5+ (B cells), CD45+, CD3+, CD4+, CD25+ (activated helpers, early activation phase), CD45+, CD3+, HLA-DR (activated T lymphocytes late activation phase). The data obtained indicate that the relative indices of T helper subpopulations, T cells at early and late activation step, and B lymphocytes were increased in the patients with acute coronary syndrome, compared with control group. At the same time, there is a trend for increasing absolute values of these indexes. The subpopulation of TNK lymphocytes proved to be significantly increased both in relative and absolute values, whereas percentages of CD45+CD3+CD19- (p 0.01) and T cytotoxic lymphocytes (p 0.001) were decreased and showed the same trend in absolute terms. The ratio of CD4/CD8 lymphocytes was almost doubled (p 0.001), due to increased content of T-helpers and decrease in cytotoxic T lymphocytes. In clinical blood analyses of ACS patients a tendency for leukocytosis was shown, (10.155.22), with a shift to the band forms.
... Studies have found that TLR7 may regulate inflammation in atherosclerosis by inhibiting the effects of pro-inflammatory cytokines. 402 In addition to the production of plaque, cell-free DNA (cfDNA) is also released in atherosclerotic lesions. TLR9 recognizes cfDNA and plays a key role in the development of vascular inflammation and atherosclerosis by promoting the pro-inflammatory activation of macrophages. ...
Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens, apoptotic host cells, and damaged senescent cells. PRRs bridge nonspecific immunity and specific immunity. Through the recognition and binding of ligands, PRRs can produce nonspecific anti-infection, antitumor, and other immunoprotective effects. Most PRRs in the innate immune system of vertebrates can be classified into the following five types based on protein domain homology: Toll-like receptors (TLRs), nucleotide oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), C-type lectin receptors (CLRs), and absent in melanoma-2 (AIM2)-like receptors (ALRs). PRRs are basically composed of ligand recognition domains, intermediate domains, and effector domains. PRRs recognize and bind their respective ligands and recruit adaptor molecules with the same structure through their effector domains, initiating downstream signaling pathways to exert effects. In recent years, the increased researches on the recognition and binding of PRRs and their ligands have greatly promoted the understanding of different PRRs signaling pathways and provided ideas for the treatment of immune-related diseases and even tumors. This review describes in detail the history, the structural characteristics, ligand recognition mechanism, the signaling pathway, the related disease, new drugs in clinical trials and clinical therapy of different types of PRRs, and discusses the significance of the research on pattern recognition mechanism for the treatment of PRR-related diseases.
... In addition, TLR7/8 agonists were identified as effective candidate adjuvants in vaccine research (Hu et al., 2020). Moreover, TLR7 was shown to be protective in atherosclerosis (Karadimou et al., 2017). The TLR7 agonist R848 was reported to promote survival in cancer (Michaelis et al., 2019). ...
S. japonicum infection can induce granulomatous inflammation in the liver of the host. Granulomatous inflammation limits the spread of infection and plays a role in host protection. Toll-like receptor 7 (TLR7) is an endosomal TLR that recognizes single-stranded RNA (ssRNA). In this study, the role of TLR7 in S. japonicum infection-induced hepatitis was investigated in both normal and TLR7 knockout (KO) C57BL/6 mice. The results indicated that TLR7 KO could aggravate S. japonicum infection-induced damage in the body, with less granuloma formation in the tissue, lower WBCs in blood, and decreased ALT and AST in the serum. Then, the expression of TLR7 was detected in isolated hepatic lymphocytes. The results indicated that the percentage of TLR7⁺ cells was increased in the infected mice. Hepatic macrophages, DCs, and B cells could express TLR7, and most of the TLR7-expressing cells in the liver of infected mice were macrophages. The percentage of TLR7-expressing macrophages was also increased after infection. Moreover, macrophages, T cells, and B cells showed significant changes in the counts, activation-associated molecule expression, and cytokine secretion between S. japonicum-infected WT and TLR7 KO mice. Altogether, this study indicated that TLR7 could delay the progression of S. japonicum infection-induced hepatitis mainly through macrophages. DCs, B cells, and T cells were involved in the TLR7-mediated immune response.
... In addition, the value of TLRs may predict the prognosis of ICH. More Specifically, Greater TLR7 values in atherosclerotic plaques removed by carotid endarterectomy were associated with a better outcome with a lower risk of cerebrovascular complications in an 8-year follow-up study in 123 patients [202]. ...
Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.
... Воспаление в нестабильной каротидной бляшке вызывает острое церебральное событие. Инфильтрация атеросклеротического поражения иммунными клетками, такими как макрофаги и Т-лимфоциты, может привести к инфаркту миокарда (ИМ) или ИИ [16]. Воспаление стенки кровеносного сосуда является важным компонентом атеросклероза и вызывает отек, рост vasa vasorum, инфильтрацию иммунных клеток и высокую метаболическую активность в воспаленных бляшках [17]. ...
... ГМ-КСФ увеличивает апоптоз макрофагов в прогрессирующих поражениях. Эти эффекты опосредуются IL-23, который секретируется после активации TLR7 [16]. ...
... Активация TLR7 модулирует баланс между индукцией и подавлением воспаления. Хотя ответ на эндогенные лиганды TLR7 в бляшках неизвестен, можно предположить, что в атерогенезе это равновесие склоняется в пользу воспаления, а после удаления бляшки TLR7 может быть частью модуляции воспалительных реакций, противодействующей эффекту провоспалительных цитокинов [16]. ...
Early recognition of rupture-prone atherosclerotic lesions in patients with high-graded carotid stenosis is an important clinical problem for preventing ischemic stroke. Various pathophysiological mechanisms are responsible for the progression and instability of plaques, such as changes in lipid composition, infiltration by immunoinflammatory cells and degradation of the extracellular matrix of the vascular wall by matrix metalloproteinases, enhanced inflammatory response and plaque neovascularization. These features are the main cause of plaque rupture and, as a consequence, neurologic symptoms. Therefore, matrix metalloproteinases and inflammatory factors can serve as possible markers for patients with severe unstable stenosis of carotid arteries. Due to the heterogeneity of atherosclerotic lesions, only one biomarker is not enough to reliably predict the development of a stroke. The use of a combination of biomarkers is better correlated with clinical data and, therefore, exceeds the analysis of individual factors. To increase the overall sensitivity and specificity and more reliable diagnosis of stroke in patients with symptomatic and asymptomatic carotid stenosis, the biomarker panel should include independent biomarkers. Further preclinical experiments and clinical trials are needed to assess the significance and precise definition of the threshold levels of such biomarkers before they can be used in clinical practice.
... Carotid endarterectomies (carotid plaques, CP) were collected at surgery and retained within the Biobank of Karolinska Endarterectomies (BiKE). The BiKE study cohort demographics, details of sample collection, processing and analyses were previously described (19)(20)(21) All human samples and data in BiKE are collected with written informed consent from patients or organ donors' guardians. Tissue and blood sampling are conducted as part of the ordinary medical and surgical procedures. ...
Objectives and Aims: Vascular smooth muscle cells (VSMCs) are key constituents of both normal arteries and atherosclerotic plaques. They have an ability to adapt to changes in the local environment by undergoing phenotypic modulation. An improved understanding of the mechanisms that regulate VSMC phenotypic changes may provide insights that suggest new therapeutic targets in treatment of cardiovascular disease (CVD). The amino-acid glutamate has been associated with CVD risk and VSMCs metabolism in experimental models, and glutamate receptors regulate VSMC biology and promote pulmonary vascular remodeling. However, glutamate-signaling in human atherosclerosis has not been explored.
Methods and Results: We identified glutamate receptors and glutamate metabolism-related enzymes in VSMCs from human atherosclerotic lesions, as determined by single cell RNA sequencing and microarray analysis. Expression of the receptor subunits glutamate receptor, ionotropic, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA)-type subunit 1 (GRIA1) and 2 (GRIA2) was restricted to cells of mesenchymal origin, primarily VSMCs, as confirmed by immunostaining. In a rat model of arterial injury and repair, changes of GRIA1 and GRIA2 mRNA level were most pronounced at time points associated with VSMC proliferation, migration, and phenotypic modulation. In vitro , human carotid artery SMCs expressed GRIA1, and selective AMPA-type receptor blocking inhibited expression of typical contractile markers and promoted pathways associated with VSMC phenotypic modulation. In our biobank of human carotid endarterectomies, low expression of AMPA-type receptor subunits was associated with higher content of inflammatory cells and a higher frequency of adverse clinical events such as stroke.
Conclusion: AMPA-type glutamate receptors are expressed in VSMCs and are associated with phenotypic modulation. Patients suffering from adverse clinical events showed significantly lower mRNA level of GRIA1 and GRIA2 in their atherosclerotic lesions compared to asymptomatic patients. These results warrant further mapping of neurotransmitter signaling in the pathogenesis of human atherosclerosis.
