Contribution of toll-like receptor 9 gene single-nucleotide polymorphism to systemic lupus erythematosus

Toll-Like Receptor 9 (TLR9) Gene C/T (rs352140) Polymorphisms in Adult Primary Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet count and increased bleeding risk. The initial event(s) leading to antiplatelet autoimmunity remains unclear. Toll-like receptors (TLRs) are the most well-characterized pattern recognition receptors and are a transmembrane protein coded by the Toll genes family. In addition to their protective role in immunity, it is also becoming clear that TLRs exhibit homeostatic roles. Toll-like receptors play potential roles in the development of disease and its maintenance. The objective of this study is to evaluate the distribution of TLR9 gene C/T (rs352140) polymorphisms and its possible association with clinicopathological finding in Egyptian adult primary ITP. This study was carried out at Internal Medicine Department, Menoufia University Hospital, Egypt, from August 2018 to January 2020. Eighty adults (≥ 18 years) were enrolled in the study; 40 patients with primary ITP and 40 healthy individuals as controls. Identification of the TLR9 C/T (rs352140) polymorphic variant was performed by polymerase chain reaction–restriction fragment length polymorphism. In our study, we excluded any other causes of secondary ITP. Distribution of the TLR9 C/T genotypes did not exhibit significant deviation between patients and controls. There was no significant difference between studied groups as regards allele (C and T) frequency. There was no significant difference regarding TLR9 gene C/T (rs352140) polymorphisms between Egyptian adult with primary ITP and controls. TLR9 gene C/T (rs352140) polymorphisms have no relation to any of the clinicohematological variables in primary ITP in Egyptians.

TLR4 and TLR9 polymorphisms are not associated with either rheumatoid arthritis or systemic lupus erythematosus in Mexican patients

Toll-like receptor (TLR)-mediated signaling pathways induce a proinflammatory microenvironment to eradicate pathogens. However, in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), TLRs can promote chronic inflammation. It has been shown that some TLR4 and TLR9 single nucleotide polymorphisms (SNPs) are risk factors for RA and SLE, but these findings have not been replicated in all populations; thus, results are inconclusive. We evaluated the TLR4 Asp299Gly, Thr399Ile, - 1892G/A SNPs, and the TLR9 Pro545Pro SNP to assess potential associations with RA and SLE in Mexican patients. This study included 474 patients with RA, 283 patients with SLE, and 424 healthy controls. We used a 5' nuclease allelic discrimination assay to genotype individuals for the four TLR4 and TLR9 polymorphisms. We found that the genotype or allelic frequencies of the TLR4 Asp299Gly, Thr399Ile, - 1892G/A, and TLR9 Pro545Pro polymorphisms were similar between patients and controls. We found no association under different genetic models. A haplotype analysis of TLR4 showed no association with either RA or SLE. We found no significant differences in the allelic or genotypic frequencies of TLR4 Asp299Gly, Thr399IIe, - 1892G/A, or TLR9 Pro545Pro between patients and controls. These findings suggested that these variants are not risk factors for RA or SLE in Mexican patients.

Association of Toll-like receptor 3 and Toll-like receptor 9 single-nucleotide polymorphisms with hepatitis C virus persistence among Egyptians

Toll-like receptors (TLRs) give the innate immune system a considerable specificity for a large range of pathogens. TLR3 detects dsRNA of viruses while TLR9 recognizes bacterial and viral unmethylated CpG motifs. This study examined whether there is a potential association between single-nucleotide polymorphisms (SNPs) in the TLR3.rs3775290 (c.1377C/T), TLR9.rs5743836 (-1237T→C) and TLR9.rs352140 (G2848A) genes and HCV infection among Egyptian patients and healthcare workers (HCWs). We enrolled 546 subjects (409 HCWs and 137 patients) divided into four groups: group 1 included 265 seronegative, aviremic subjects; group 2 included 25 seronegative, viremic subjects; group 3 included 87 subjects with spontaneously resolved HCV infection; and group 4 included 169 chronic HCV patients. All subjects were genotyped for TLR3.rs3775290, TLR9.rs5743836 and TLR9.rs352140 SNPs by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. TLR3.rs3775290 "CC" genotype was associated with chronic HCV infection, where there was a significantly greater frequency of this genotype among chronic patients when compared to subjects with spontaneously resolved infection (63.9% vs. 51.9%; p = 0.033; OR = 1.639 and 95% CI = 0.94-2.84). However, this SNP did not correlate with the HCV RNA load among the chronic subjects (p > 0.05). There was no significant difference in TLR9.rs5743836 and TLR9.rs352140 genotype distribution between groups (p > 0.05). Lack of association between the three SNPs was found, as the three SNPs are located on two different chromosomes. In conclusion, the TLR3.rs3775290 "CC" genotype was associated with HCV chronicity, while the TLR9 gene may not play a major role in HCV infection.

From autoinflammation to autoimmunity: old and recent findings

Autoimmune diseases and autoinflammatory diseases have a number of similar etiopathogenetic and clinical characteristics, including genetic predisposition and recurrent systemic inflammatory flares. The first phase of ADs involves innate immunity: by means of TLRs, autoantigen presentation, B and T cell recruitment and autoantibody synthesis. The second phase involves adaptive immunity, a self-sustaining process in which immune complexes containing nucleic acids and autoantibodies activate self-directed inflammation. The link between autoimmunity and autoinflammation is IL-1ß, which is crucial in connecting the innate immune response due to NLR activation and the adaptive immune responses of T and B cells. In conclusion, although ADs are still considered adaptive immunity-mediated disorders, there is increasing evidence that innate immunity and inflammasomes are also involved. The aim of this review is to highlight the link between the innate and adaptive immune mechanisms involved in autoimmune diseases.

TH1 and TH2 Cytokine Profiles as Predictors of Severity in Acute Pancreatitis

OBJECTIVES

Acute pancreatitis (AP) is severe in up to 20% of patients, with a high mortality rate. Quantification of serum TH1 and TH2 cytokines may provide objective evidence to assess the severity of AP and predict its course.

METHODS

One hundred seventeen patients were studied, measuring serum concentrations of interleukin (IL)1β, IL2, IL4, IL5, IL6, IL10, IL12p70, IL13, IL18, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN) γ, and tumor necrosis factor (TNF) α.

RESULTS

Significant differences were found between patients with severe AP and those with mild or moderately severe AP in IFN-γ (P < 0.001), IL6 (P < 0.001), TNF-α (P = 0.002), GM-CSF (P < 0.001), IL4 (P = 0.002), IL1b (P = 0.017), and IL13 (P < 0.001) concentrations. Interferon-γ, IL6, and TNF-α were associated with severe AP, whereas GM-CSF, IL4, IL1b, and IL13 were associated with mild or moderately severe AP. The IL13/IFNγ ratio was significantly higher in patients with mild AP (P = 7.36 × 10).

CONCLUSIONS

A TH1 profile was associated with severe AP and a TH2 profile with mild or moderately severe AP. We report an IL13/IFNγ ratio of potential value to predict the prognosis in AP.

Associations between PTPN22 and TLR9 polymorphisms and systemic lupus erythematosus: a comprehensive meta-analysis

Previous studies have explored the relationship of PTPN22 and TLR9 polymorphisms with systemic lupus erythematosus (SLE). In consideration of the population stratification, conflicting results and updating data, we conducted a comprehensive meta-analysis, which consists of a total of 17 research articles (9120 cases and 11,724 controls) for PTPN22 and 20 articles (including up to 2808 cases and 3386 controls) for TLR9. Significant association was verified between PTPN22 rs2476601 and SLE in the overall population (OR = 1.511 per T allele, 95% CI 1.338-1.706, P = 2.931 × 10^-11) and under dominant model of T allele (TT+CT vs. CC: OR = 1.531, 95% CI 1.346-1.742, P = 9.17 × 10^-11). Analysis after stratification by ethnicity indicated that PTPN22 rs2476601 was related to SLE in Americans (OR = 2.566, 95% CI 1.796-3.665, P = 2.219 × 10^-7), Europeans (OR = 1.399, 95% CI 1.261-1.552, P = 2.153 × 10^-10), and Africans (OR = 4.14, 95% CI 1.753-9.775, P = 1.0 × 10^-3). We did not observe any association between TLR9 polymorphisms (rs187084, rs352140, rs5743836 and rs352139) and SLE under any model, after excluding the data that were inconsistent with Hardy-Weinberg equilibrium (HWE). In summary, PTPN22 rs2476601 was significantly interrelated with SLE and contributed to susceptibility and development of SLE in Americans, Europeans and Africans in this analysis, while their relationship needs to be validated in Africans by future research.

TLR9 -1486T/C and 2848C/T SNPs Are Associated with Human Cytomegalovirus Infection in Infants

Toll-like receptor 9 (TLR9) recognizes non-methylated viral CpG-containing DNA and serves as a pattern recognition receptor that signals the presence of human cytomegalovirus (HCMV). Here, we present the genotype distribution of single-nucleotide polymorphisms (SNPs) of the TLR9 gene in infants and the relationship between TLR9 polymorphisms and HCMV infection. Four polymorphisms (-1237T/C, rs5743836; -1486T/C, rs187084; 1174G/A, rs352139; and 2848C/T, rs352140) in the TLR9 gene were genotyped in 72 infants with symptomatic HCMV infection and 70 healthy individuals. SNP genotyping was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Digested fragments were separated and identified by capillary electrophoresis. The HCMV DNA copy number was measured by a quantitative real-time PCR assay. We found an increased frequency of heterozygous genotypes TLR9 -1486T/C and 2848C/T in infants with HCMV infection compared with uninfected cases. Heterozygous variants of these two SNPs increased the risk of HCMV disease in children (P = 0.044 and P = 0.029, respectively). In infants with a mutation present in at least one allele of -1486T/C and 2848C/T SNPs, a trend towards increased risk of cytomegaly was confirmed after Bonferroni's correction for multiple testing (Pc = 0.063). The rs352139 GG genotype showed a significantly reduced relative risk for HCMV infection (Pc = 0.006). In contrast, the -1237T/C SNP was not related to viral infection. We found no evidence for linkage disequilibrium with the four examined TLR9 SNPs. The findings suggest that the TLR9 -1486T/C and 2848C/T polymorphisms could be a genetic risk factor for the development of HCMV disease.

Association between toll-like receptor polymorphisms and systemic lupus erythematosus: a meta-analysis update

OBJECTIVE

The aim of this study was to determine whether polymorphisms of the Toll-like receptor (TLR) genes are associated with susceptibility to systemic lupus erythematosus (SLE).

METHODS

The authors conducted a meta-analysis of the relationship between 12 TLR polymorphisms and SLE susceptibility.

RESULTS

In total, 26 studies that involved 11,984 patients and 14,572 controls were included in the meta-analysis. The meta-analysis showed no association between the two alleles of the rs352140, rs5743836, and rs352139 polymorphisms of TLR9 and SLE, but indicated an association between the two alleles of the rs187084 polymorphism (TLR9) and SLE in the overall population (OR = 0.869, 95% CI = 0.762-0.992, P = 0.038). No association was detected between rs3764880 (TLR8) and SLE; however, our meta-analysis indicated an association between rs3764879 (TLR8) and SLE in Caucasians (OR = 1.414, 95% CI = 1.139-1.756, P = 0.002). An association between rs179008 (TLR7) and SLE was found in the African (OR = 0.430, 95% CI = 0.238-0.775, P = 0.005), but not in the Caucasian population (OR = 1.206, 95% CI = 0.932-1.614, P = 0.145). Furthermore, our meta-analysis indicated a significant association between rs3853839 (TLR7) and SLE in the Asian population (OR = 0.773, 95% CI = 0.735, 0.823, P < 1.0 × 10(-9)). No associations were found between rs5744168 (TLR5), rs4986791 (TLR4), rs4986790 (TLR4), and rs3775291 (TLR3) polymorphisms and SLE susceptibility.

CONCLUSIONS

Our meta-analysis suggests that TLR7, TLR8, and TLR9 polymorphisms are associated with the development of SLE in Caucasian, Asian, and African populations.

TLR9 polymorphisms and systemic lupus erythematosus risk: an update meta-analysis study

It has been reported that the Toll-like receptor 9 (TLR9) gene polymorphisms may be associated with systemic lupus erythematosus (SLE) risk. However, some studies yielded conflicting results. Therefore, a comprehensive meta-analysis was performed to assess the precise association between TLR9 polymorphisms and SLE susceptibility. We performed a systematic search in PubMed, Embase (Ovid), China National Knowledge Internet, and Wanfang databases up to July 15, 2015. Odds ratio (OR) and 95 % confidence interval (CI) were used to pool the effect size. Statistical analyses were performed with STATA 11.0 software. In total, 21 studies from nineteen articles with 10,273 subjects were included in this meta-analysis. The overall results suggested that there was a statistically significant association between TLR9 rs187084 polymorphism and SLE risk observed in recessive model (TT vs. TC + CC: OR 1.17, 95 % CI 1.05-1.30, P = 0.005), codominant model (TT vs. CC: OR 1.22, 95 % CI 1.03-1.43, P = 0.019), and allele model (T vs. C: OR 1.15, 95 % CI 1.02-1.30, P = 0.020) in Asians. However, we found that there may be no significant association between the other three TLR9 polymorphisms and SLE risk in either Asians or non-Asians. In conclusion, the meta-analysis results suggested that TLR9 rs187084 polymorphism may increase the risk of SLE in Asians. However, no significant association between TLR9 SNPs (rs352139, rs352140, and rs5743836) and SLE risk was identified.

Translating nucleic acid-sensing pathways into therapies

Nucleic acid sensing by innate receptors initiates immune defences against viruses and other pathogens. A hallmark of this response is the release of interferons (IFNs), which promote protective immunity by inducing IFN-stimulated genes (ISGs). A similar ISG signature is found in autoinflammatory and autoimmune conditions, indicating that chronic activation of nucleic acid-sensing pathways may contribute to these diseases. Here, we review how nucleic acid-sensing pathways are currently being targeted pharmacologically with both agonists and antagonists. We discuss how an improved understanding of the biology of these pathways is leading to novel therapies for infections, cancer, and autoimmune and autoinflammatory disorders, and how new therapeutics will, in turn, generate a deeper understanding of these complex diseases.

Inflammasomes and human autoimmunity: A comprehensive review

Inflammasomes are multi-protein complexes composed of a NOD-like receptor (NLR)/an AIM-like receptor (ALR), the adapter molecule apoptosis-associated speck-like protein that contains a CARD (ASC), and caspase-1. Active caspase-1 cleaves pro-IL-1β and pro-IL-18 to IL-1β and IL-18, resulting in inflammation. Genetic mutations in inflammasomes were first recognized to result in autoinflammatory diseases, which are characterized by the absence of both autoantibodies and autoreactive-T/B cells. However, there is increasing attention being placed on genetic polymorphisms that are involved in the components of inflammasomes, and these have implications for innate immunity and the natural history of autoimmune diseases. For example, while the NOD-like receptor family, pyrin domain containing 1 (NLRP1) haplotypes contributes to susceptibility to developing vitiligo; there are other single nucleotide polymorphisms (SNPs) that alters the susceptibility and severity of rheumatoid arthritis (RA) and juvenile idiopathic arthritis. Indeed, there are multiple factors that contribute to lowering the threshold of immunity and inflammasomes play a key role in this threshold. For example, IL-1β and IL-18 further perpetuate Th17 responses and endothelial cell damage, which potentiate a number of autoimmune diseases, including synovitis in RA, cardiovascular disease, and systemic lupus erythematosus (SLE). There is also increasing data on the role of innate immunity in experimental autoimmune encephalomyelitis (EAE), in lupus nephritis, and in a variety of autoimmune pathologies in which activation of the innate immune system is the driver for the adaptive system. Indeed, it is likely that the chronic pathology of autoimmunity is mediated in part by otherwise innocent bystander cells, augmented by inflammasomes.

Toll-like receptor gene polymorphisms and susceptibility to Epstein-Barr virus-associated and -negative gastric carcinoma in Northern China

BACKGROUND/AIMS

Various polymorphisms in toll-like receptor (TLR) genes have been identified and associated with susceptibility to various malignancies, such as gastric carcinoma (GC), breast cancer, and prostate cancer. However, little is known about the polymorphisms of TLR genes and the susceptibility to GC in Northern China, especially to Epstein-Barr virus-associated GC (EBVaGC). We focused on the association with susceptibility to GC, especially to EBVaGC.

PATIENTS AND METHODS

Polymorphisms of the TLR2, 3, 4, and 9 genes were measured in 52 cases of EBVaGC and 157 cases of EBV-negative GC (EBVnGC). Ninety-four peripheral blood samples from healthy individuals were also examined.

RESULTS

For the TLR2 gene (196 to 174 del), there was no significant difference between the GC group and control group in genotype, but there was a significant difference in the del allele. As for the TLR3 gene (c. 1377C/T), there were significant differences between the GC group and the control group in both genotype and allelic frequency. No SNPs single nucleotide polymorphisms (SNPs) were found in the TLR4 gene at the sites Asp299Gly and Thr399Ile. As for TLR9 1486T/C (rs187084) and C2848T (rs352140), there was also no association between the GC group and control. In all of the indicators, there were no significant differences between EBVaGCs and EBVnGCs.

CONCLUSIONS

The TLR3 gene (c. 1377C/T) polymorphisms and the del allele of the TLR2 gene ( 196 to 174) were both associated with susceptibility to GC in Shangdong Province of Northern China. There was no interaction between EBV and TLR gene polymorphisms in EBVaGC.

Toll-like receptors in systemic lupus erythematosus: potential for personalized treatment

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by the loss of tolerance to self-nuclear antigens. The symptoms of SLE, progression of pathology and the array of autoantibodies present in the serum differ significantly from patient to patient, which calls for a personalized approach to treatment. SLE is polygenic and strongly influenced by gender, ethnicity, and environmental factors. Data from genome-wide association studies suggests that polymorphisms in as many as 100 genes contribute to SLE susceptibility. Recent research has focused on genes associated with Toll-like receptors (TLRs), type I interferons, immune regulation pathways, and immune-complex clearance. TLR7 and TLR9 have been extensively studied using lupus-prone mouse models. In multiple systems overexpression of TLR7 drives disease progression but interestingly, a loss of TLR9 results in an almost identical phenotype. While TLR7 overexpression has been linked to human SLE, the possible role of TLR9 in human disease remains elusive. In the present review, we focus on TLR polymorphisms and TLR expression in SLE patients and discuss their potential as biomarkers for individualized treatment.

Association study of TLR-9 polymorphisms and systemic lupus erythematosus in northern Chinese Han population

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease, with multiple genetic and environmental factors involving in its etiology. The toll-like receptor 9 (TLR9) gene has been reported to have important roles in the development and progression of SLE. We performed a case-control study to investigate the effects of 4 SNPs in the TLR9 gene in the development of SLE in Northern Chinese population.

METHODS

Four SNPs including rs187084, rs5743836, rs352139 and rs352140 were genotyped using the SNaPshot® method. A group of 430 SLE patients were compared to 424 normal controls. Data were analyzed by SPSS 17.0 and HaploView v 4.1 software.

RESULTS

The frequency distributions of SNP rs351240 and haplotype H2 (TGCT) and H3 (CATT) were found to differ significantly between patient and control groups (p<0.05), while other SNPs and haplotypes showed no significant difference between the two cohorts (p>0.05).

CONCLUSION

The results revealed that variations in the TLR9 gene are associated with SLE, indicating that TLR9 may play an important role in the pathogenesis of SLE in the northern Chinese Han population.

Toll-like receptor 9 promoter polymorphism is associated with decreased risk of Alzheimer's disease in Han Chinese

Background

Toll-like receptors (TLRs), as major innate immune mediators, may be involved in clearance of cerebral amyloid-β (Aβ) deposits. Recently, a novel TLR9 signaling pathway has been uncovered, which is functionally associated with the immune inflammatory response and reducing Aβ burden in Alzheimer’s disease (AD) mice. Therefore, TLR9 might represent a reasonable functional candidate gene for AD.

Findings

Our study investigated 1,133 sporadic late-onset AD (LOAD) and 1,159 healthy controls matched for sex and age in a large Han Chinese population. One selected functional rs187084 polymorphism within the TLR9 gene was genotyped by polymerase chain reaction-ligase detection reaction in a case–control associated study. The TLR9 rs187084 variant homozygote GG was significantly associated with a decreased LOAD risk after adjusting for age, gender, and ApoE ϵ4 status by logistic regression analysis (P = 0.035). Our result showed significant evidence of the interaction of ApoE ϵ4 with rs187084. When we further stratified our data by the ApoE ϵ4 status, we detected significant differences in the genotype and allele distributions of rs187084 between LOAD patients and controls in ApoE ϵ4 carriers (P < 0.001, P = 0.003, respectively). Moreover, we examined TLR9 expression in peripheral blood monocytes by flow cytometry, and the GG genotype of the TLR9 rs187084 polymorphism was associated with a higher TLR9 expression than two other genotypes in LOAD patients.

Conclusion

Our findings support the hypothesis that the TLR9 polymorphism may modify LOAD risk in the Han Chinese population.