Analysis of single nucleotide polymorphisms in Toll-like receptor 4 shows no association with ankylosing spondylitis in a Korean population

Targeting Toll-like Receptor (TLR) Pathways in Inflammatory Arthritis: Two Better Than One?

Inflammatory arthritis is a cluster of diseases caused by unregulated activity of the immune system. The lost homeostasis is followed by the immune attack of one’s self, what damages healthy cells and tissues and leads to chronic inflammation of various tissues and organs (e.g., joints, lungs, heart, eyes). Different medications to control the excessive immune response are in use, however, drug resistances, flare-reactions and adverse effects to the current therapies are common in the affected patients. Thus, it is essential to broaden the spectrum of alternative treatments and to develop disease-modifying drugs. In the last 20 years, the involvement of the innate immune receptors TLRs in inflammatory arthritis has been widely investigated and targeting either the receptor itself or the proteins in the downstream signalling cascades has emerged as a promising therapeutic strategy. Yet, concerns about the use of pharmacological agents that inhibit TLR activity and may leave the host unprotected against invading pathogens and toxicity issues amid inhibition of downstream kinases crucial in various cellular functions have arisen. This review summarizes the existing knowledge on the role of TLRs in inflammatory arthritis; in addition, the likely druggable related targets and the developed inhibitors, and discusses the pros and cons of their potential clinical use.

Associations of toll-like receptor 4 and 2 gene polymorphisms with susceptibility to ankylosing spondylitis: A meta-analysis

BACKGROUND

The published evidences on the correlations of toll-like receptor 4 (TLR4) and TLR9 gene polymorphisms and ankylosing spondylitis (AS) were conflicting. The purpose of this study was to investigate whether TLR4 and TLR9 gene polymorphisms conferred susceptibility to AS through a meta-analysis approach.

METHODS

Databases of PubMed, Web of Science, EMBASE, Cochrane Library, CNKI and Wanfang were retrieved for relevant publications up to 20 June 2020. Study quality was assessed based on Newcastle-Ottawa scale (NOS). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to judge the associations.

RESULTS

Totally, 13 articles with 3,055 AS cases and 4,238 controls were incorporated into this meta-analysis, and four most widely reported polymorphisms (TLR4-rs4986790, TLR4-rs4986791, TLR9-rs55704465 and TLR9-rs187084) were analysed. All included studies were in high quality. The pooled data did not support any significant association between the four studied polymorphisms and AS susceptibility.

CONCLUSIONS

The present meta-analysis suggests there is no significant association between TLR4-rs4986790, TLR4-rs4986791, TLR9-rs55704465 and TLR9-rs187084 polymorphisms and AS.

Toll-like receptor 4 (TLR4) polymorphisms in Iranian patients with visceral leishmaniasis

The role of Toll-like receptor (TLR) 4 in visceral leishmaniasis (VL), a disease caused by an obligate intracellular protozoan parasites belonging to the genus Leishmania, has been shown in the recent leishmaniasis experimental studies. As genetic host factors play an important role in the susceptibility and/or resistance to VL, the association between TLR4 gene mutations [A896G and C1196T single nucleotide polymorphisms (SNPs)] and VL was investigated. Genotyping of A896G (Asp299Gly) and C1196T (Thr399Ile) SNPs was performed in the patients with VL (N = 122) and ethnically matched controls (N = 155) using polymerase chain reaction-restriction fragment length polymorphism method. When VL patients and the controls were compared, no statistically significant differences were observed in A896G and C1196T alleles and genotypes (P > 0.05). The TLR4 A896G and C1196T were in moderate linkage disequilibrium in the controls and patients (r (2) = 0.497, 0.548 and D' = 0.705, 0.808, respectively), and haplotypes reconstructed from these SNPs were not significantly different between the aforementioned study groups. In conclusion, based on the results, TLR4 gene polymorphisms at the positions 896 and 1196 cannot be regarded as the major contributors to VL susceptibility among the Iranian population.

Lack of association of TLR4 polymorphisms with susceptibility to rheumatoid arthritis and ankylosing spondylitis: a meta-analysis

OBJECTIVE

The aim of the study was to determine whether polymorphisms of toll-like receptor 4 (TLR4) confer susceptibility to rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

METHODS

A meta-analysis was conducted on the association between the D299G/T399I polymorphisms and RA/AS (when available) using (1) the allelic contrast, (2) the recessive, (3) the dominant, and (4) the additive models.

RESULTS

A total of eleven relevant studies met the inclusion criteria were identified, including RA: D299G (six studies), T399I (three studies); AS: D299G (five studies), T399I (four studies). Meta-analysis was performed with fixed/random effect models. Overall, no significant RA/AS risk was found in all genetic models when all studies were pooled into the meta-analysis (P>0.05).

CONCLUSIONS

The present study might suggest that TLR4 D299G/T399I polymorphisms are not associated with RA/AS susceptibility.

Lack of association of single nucleotide polymorphisms in toll-like receptors 2 and 4 with enthesitis-related arthritis category of juvenile idiopathic arthritis in Indian population

Toll-like receptors 2 and 4 are over expressed in patients with enthesitis-related arthritis and cause increased production of pro-inflammatory cytokines. This aberrant functioning could be due to polymorphisms in TLR2 and TLR4. Hence, we genotyped ERA patients for Arg753Gln and Arg677Trp polymorphism in TLR2 gene and Asp299Gly and Thr399Ile polymorphism in TLR4 gene. DNA was extracted from blood from ERA patients and healthy controls. All four polymorphisms were studied by PCR-RFLP method. 200 healthy controls and 97 ERA patients were enrolled. All healthy controls and patients had wild-type allele for Arg753Gln and Arg677Trp TLR2 polymorphism. Regarding TLR4, Asp299Gly polymorphism A allele frequency was 90 % in controls and 96 % in patients (OR 2.7, 95 % CI 0.81-8.8). GG homozygous genotype was detected in one healthy control and was absent from patients. The TLR4 Thr399Ileu variant was not detected in patients. Out of 200 healthy controls, 10 were heterozygous (5 %) and only one was homozygous for rare variant (0.5 %). Polymorphisms in TLR2 and TLR4 are not associated with ERA.

The potential importance of Toll-like receptors in ankylosing spondylitis

Cells involved in innate immunity scan for pathogens via extracellular and intracellular (endosomal) pattern recognition receptors (PRRs). Engagement of PRRs by a specific ligand results in downstream activation of intracellular inflammatory cascades. There is emerging evidence indicating that one class of PRR, the Toll-like receptor (TLR) plays a potential role in the pathogenesis of spondyloarthropathies. Since certain Gram-negative bacteria are known to act as triggers for reactive arthritis, there has been much interest in studying the role of TLRs in spondyloarthropathies. In this article, we introduce the immunology of TLRs followed by a discussion of their potential role in ankylosing spondylitis.

Toll-Like Receptor 2 Gene Polymorphisms in a Korean Population

Objective. To investigate the role of single-nucleotide polymorphisms (SNPs) in the gene encoding Toll-like receptor (TLR) 2 in Korean patients with chronic rhinosinusitis (CRS) and controls.

Study Design and Setting. A case-control study.

Subjects and Methods. Subjects (N = 214) were all adults (>20 years old) and were divided into patients with CRS (n = 106) and controls (n = 108). Five SNPs (rs1898830, rs3804099, rs3804100, R677W, and rs5743708) were selected and genotyped in a case-control study with the single-base-pair primer extension (SNaPshot) assay.

Results. The case-control study revealed that 2 SNPs in TLR2, rs3804099 (odds ratio [OR] = 2.88; 95% confidence interval [CI] = 1.17-7.09; P = .022) and rs3804100 (OR = 3.76; 95% CI = 1.42-9.96; P = .008), showed significant differences in minor allele frequency between CRS patients and controls. These 2 SNPs were correlated with CRS risk in Korean patients.

Conclusions. Two SNPs in TLR2 may be associated with increased risk of CRS in Korean subjects.