Polymorphisms of toll-like receptor 2 and 4 genes in rheumatoid arthritis and systemic lupus erythematosus

Human and Murine Toll-like Receptor-Driven Disease in Systemic Lupus Erythematosus

The pathogenesis of systemic lupus erythematosus (SLE) is linked to the differential roles of toll-like receptors (TLRs), particularly TLR7, TLR8, and TLR9. TLR7 overexpression or gene duplication, as seen with the Y-linked autoimmune accelerator (Yaa) locus or TLR7 agonist imiquimod, correlates with increased SLE severity, and specific TLR7 polymorphisms and gain-of-function variants are associated with enhanced SLE susceptibility and severity. In addition, the X-chromosome location of TLR7 and its escape from X-chromosome inactivation provide a genetic basis for female predominance in SLE. The absence of TLR8 and TLR9 have been shown to exacerbate the detrimental effects of TLR7, leading to upregulated TLR7 activity and increased disease severity in mouse models of SLE. The regulatory functions of TLR8 and TLR9 have been proposed to involve competition for the endosomal trafficking chaperone UNC93B1. However, recent evidence implies more direct, regulatory functions of TLR9 on TLR7 activity. The association between age-associated B cells (ABCs) and autoantibody production positions these cells as potential targets for treatment in SLE, but the lack of specific markers necessitates further research for precise therapeutic intervention. Therapeutically, targeting TLRs is a promising strategy for SLE treatment, with drugs like hydroxychloroquine already in clinical use.

Associations of toll-like receptor polymorphisms with systemic lupus erythematosus: A meta-analysis

Objective

The objective of this study was to examine whether polymorphisms in toll-like receptors 7 and 4 (TLR7 and 4) contribute to vulnerability to systemic lupus erythematosus (SLE).

Methods

We searched MEDLINE, Embase, and Web of Science for relevant articles and performed a meta-analysis to investigate the relationship between TLR7 rs179008, rs3853839, rs1790010, TLR4 rs4986791, and rs798690 polymorphisms and SLE.

Results

Eighteen studies and 16 papers including 8022 patients with SLE and 9822 healthy controls were retrieved. Meta-analysis revealed that the TLR7 rs179008 T variant was not associated with SLE (OR = 1.008, 95% CI = 0.849-1.394, P = 0.504). Ethnic classification revealed no association between the TLR7 rs179008 T gene and SLE in either European or Latin American groups. Additionally, homozygous comparison, recessive, and dominant models revealed no association between the TLR7 rs179008 variant and SLE. In contrast, a significant association between SLE and the TLR7 rsrs3853839 GG + GA allele (OR = 2.135, 95% CI = 1.502-3.035, <0.001; OR = 23.20, 95% CI = 14.13-38.08, <0.001) was observed in the Arab and Asian groups. The T variant of TLR7 rsrs179010 was also associated with SLE in Asians (OR = 1.177, 95% CI = 1.048-1.321, P = 0.006). In contrast, the TLR4 rs4986791 variant was not associated with SLE in Europeans when allele, homozygous comparison, recessive, and dominant models were used. Furthermore, no association between the TLR4 rs4986790 variant and SLE risk in Europeans was found using any genomic model.

Conclusions

Meta-analysis revealed that the TLR7 rs3853839 variant is associated with SLE risk in Asians and Arabs and that TLR7 rs179010 is associated with SLE in Asians. However, TLR7 rs179008, TLR4 rs4986791, and TLR rs798690 polymorphisms were not associated with SLE risk.

The Genetic Association Between TLR-1, -2, -4, and -6 Gene Polymorphisms and Rheumatoid Arthritis Susceptibility in a Chinese Han Population

Aims: The toll-like receptor (TLR) genes were shown to be involved in the pathogenesis of rheumatoid arthritis (RA). We aimed to investigate the genetic associations between the TLR-1, -2, -4, and -6 genes polymorphisms and RA susceptibility in a Chinese Han population. Methods: Six polymorphisms [TLR-1 (rs5743610, rs5743618), -2 (rs5743708), -4 (rs4986790, rs4986791), and -6 (rs5743810)] in TLRs genes were genotyped in 360 patients with RA and 560 matched healthy controls by using direct sequencing method. The odds ratios (ORs) and 95% confidence intervals (CIs) were evaluated using a standard logistic regression analysis. Results: No significant association between the allelic, dominant, and recessive models of TLR-1 rs5743610, TLR-2 rs5743708, TLR-4 rs4986790 and rs4986791, and TLR-6 rs5743810 polymorphisms and RA risk was observed (p > 0.05). However, significant associations were detected between the allelic, dominant, and recessive models of TLR-1 rs5743618 and RA risk (allelic: OR [95% CI] = 2.21 [1.73-2.81], p < 0.0001; dominant: OR [95% CI] = 2.33 [1.75-3.09], p < 0.0001; recessive models: OR [95% CI] = 3.70 [1.85-7.41], p = 0.0002). In addition, the TLR6 rs5743810 was found to be associated with the rheumatoid factor (RF)^- and anticyclic citrullinated peptide (anti-CCP)^- antibody in RA group (RF: OR [95% CI] = 2.29 [1.42-3.69], p = 0.0007; anti-CCP: OR [95% CI] = 2.33 [1.39-3.89], p = 0.001). Conclusions: The allelic, dominant, and recessive models of TLR1 rs5743618 might be associated with RA susceptibility. Also, the TLR6 rs5743810 might be associated with RF and anti-CCP antibody of RA in Chinese Han population.

Role of innate immune receptors TLR4 and TLR2 polymorphisms in systemic lupus erythematosus susceptibility

AIM

Through their recognition of various bacterial cell wall components, TLR2 and TLR4 participate in the innate response and modulate the activation of adaptive immunity. Therefore, the genetic background of these receptors might play a crucial role in autoimmune diseases such as systemic lupus erythematosus (SLE). In this study, we investigated the possible association between polymorphisms within TLR2 and TLR4 genes with SLE susceptibility.

MATERIAL AND METHODS

A total of 100 SLE patients and 200 unrelated healthy controls of the Tunisian population were enrolled in the study.TLR4rs4986790, TLR4rs4986791, and TLR2rs5743708 genotyping were performed using a polymerase chain reaction-restriction fragment length polymorphism method. The number of guanine-thymine (GT) repeat microsatellite in the intron 2 of TLR2 gene was analyzed by sequencing.

RESULTS

We reported a lack of allelic and genotypic association between SNPs of TLR4 and TLR2 genes and SLE pathogenesis. No correlation was found with any SLE features. However, SLE susceptibility was associated with the GT repeat microsatellite polymorphism in the human TLR2 gene. Further subclassification of alleles into three subclasses revealed a significant association between the long-sized repeats ((GT) >23) and SLE.

CONCLUSION

Though the results showed the absence of genetic association of TLR4 and TLR2 SNPs with the risk of developing SLE, we have identified a protective association between the microsatellite polymorphism in intron 2 of the TLR2 gene and SLE. Functionally, these (GT)n repeats may confer modifying effects or susceptibility to certain inflammatory conditions.

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.

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.

Toll-Like Receptors Gene Polymorphisms in Autoimmune Disease

Toll-like receptors (TLRs) are important initiators of the immune response, both innate and acquired. Evidence suggests that gene polymorphisms within TLRs cause malfunctions of certain key TLR-related signaling pathways, which subsequently increases the risk of autoimmune diseases. We illustrate and discuss the current findings on the role of Toll-like receptor gene polymorphisms in numerous autoimmune diseases in this review, such as type 1 diabetes mellitus, Graves’ disease, rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis. The study of genetic variation in TLRs in different populations has shown a complex interaction between immunity and environmental factors. This interaction suggests that TLR polymorphisms affect the susceptibility to autoimmune diseases differently in various populations. The identification of Toll-like receptor gene polymorphisms can expand our understanding of the pathogenesis of autoimmune diseases, which will subsequently guide effective medical management and provide insight into prognosis and advanced treatments.

Innate Immune Mechanisms of Arterial Hypertension and Autoimmune Disease

The immune system is indispensable in the development of vascular dysfunction and hypertension. The interplay between immune cells and the vasculature, kidneys, heart, and blood pressure regulating nuclei in the central nervous system results in a complex and closely interwoven relationship of the immune system with arterial hypertension. A better understanding of this interplay is necessary for optimized and individualized antihypertensive therapy. Our review article focuses on innate cells in hypertension and to what extent they impact on development and preservation of elevated blood pressure. Moreover, we address the association of hypertension with chronic autoimmune diseases. The latter are ideally suited to learn about immune-mediated mechanisms in cardiovascular disease leading to high blood pressure.

Roles of Interactions Between Toll-Like Receptors and Their Endogenous Ligands in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Systemic juvenile idiopathic arthritis (JIA) and adult-onset Still’s disease (AOSD) are systemic inflammatory disorders that manifest as high-spiking fever, joint pain, evanescent skin rash, and organomegaly. Their pathogenesis is unclear, but inflammation is triggered by activation of the innate immune system with aberrant production of proinflammatory cytokines. Along with extrinsic factors, intrinsic pathways can trigger an unexpected immune response. Damage-associated molecular patterns (DAMPs) induce the activation of innate immune cells, leading to sterile inflammation in systemic JIA and AOSD. These endogenous proteins interact with Toll-like receptors (TLRs), which are pattern recognition receptors, and mediate immune signaling following stimulation by pathogen-associated molecular patterns and DAMPs. Several DAMPs, such as S100 proteins, play a role in the development or severity of systemic JIA and AOSD, in which their interactions with TLRs are altered. Also, the expression levels of genes encoding DAMPs contribute to the susceptibility to systemic JIA and AOSD. Herein, we review reports that TLR and DAMP signaling initiates and/or maintains the inflammatory response in systemic JIA and AOSD, and their correlations with the clinical characteristics of those diseases. In addition, we assess their utility as biomarkers or therapeutics for systemic JIA and AOSD.

Association of two polymorphisms Asp299Gly and Thr399Ile in Toll-like receptor 4 with rheumatoid arthritis: A meta-analysis

Our meta-analysis aims to evaluate the association of Asp299Gly and Thr399Ile with rheumatoid arthritis (RA) susceptibility and severity. By manually searching 3 electronic databases (PubMed, Embase and Web of Science), relevant articles were collected. After checking eligibility for every study, this meta-analysis on eligible studies was performed under 5 genetic models: (1) allelic contrast; (2) heterozygous model; (3) homozygous model; (4) dominant model; (5) recessive model. In Spanish populations, a significantly decreased RA risk was identified in allelic comparison (odds ratio [OR] = 0.73, 95% CI 0.55 ~ 0.96) and dominant model (OR = 0.74, 95% CI 0.56 ~ 0.99) of Asp299Gly polymorphism. A trend of reduced risk was also observed under the heterozygous model (OR = 0.77, 95% CI 0.58 ~ 1.03). As for Thr399Ile, it might also have a protective effect on Spanish populations in allelic comparison (OR = 0.71, 95% CI 0.44 ~ 1.15). In contrast, for both Asp299Gly and Thr399Ile, a higher risk of RA was detected in Chinese Han populations. The frequency of both Asp299Gly and Thr399Ile increased in rheumatoid factor (RF)-positive subjects in Chinese patients (Asp299Gly, RF+:RF- = 0.165:0.145; Thr399Ile, RF+:RF- = 0.170:0.161) and decreased in Spanish patients (Asp299Gly, RF+:RF- = 0.060:0.073; Thr399Ile, RF+:RF- = 0.046:0.056), but not to a statistically significant extent. Our meta-analysis suggested that both Asp299Gly and Thr399Ile might have a protective effect on Spanish populations, but the 2 polymorphisms could act as a susceptible factor in Chinese Han populations. To confirm our results, further investigation concerning the functional impacts of Asp299Gly and Thr399Ile are still needed.

Promoter polymorphism (T-1486C) of TLR-9 gene is associated with knee osteoarthritis in a Turkish population

In this study, we aimed to determine whether TLR-9 T-1486C SNP was associated with susceptibility to OA in the Turkish population. The study group comprised 272 patients with Grade 2-3-4 knee OA according to the Kellgren-Lawrence scoring system and the control group was formed of 296 individuals with Grade 0-1. The TLR-9 genotype were assessed by real-time polymerase chain reaction. An analysis of TLR-9 promoter -1486T/C polymorphism revealed that the -1486CC genotype appeared to have a higher risk for OA and -1486TT and -1486CT genotypes have a protective effect against the development of OA (crude OR = 0.473, 95% CI = 0.297-0.754, p = 0.002, adjusted OR = 0.531, 95% CI = 0.326-0.864, p = 0.011). This study indicate that there is a correlation of TLR-9 T-1486C gene polymorphism with advanced knee OA in a Turkish population. Changed in TLR expression due to different allelles may cause osteoarthrith development outcome cartilage degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2484-2489, 2017.

Relevant genetic polymorphisms and kidney expression of Toll-like receptor (TLR)-5 and TLR-9 in lupus nephritis

Toll-like receptor (TLR) genetic polymorphisms may modify their expression causing inflammatory disorders and influencing both susceptibility and severity of lupus erythematosus. We aim to determine whether TLR-5 and TLR-9 gene polymorphisms are implicated in the susceptibility to systemic lupus erythematosus (SLE) and lupus nephritis (LN) and to evaluate their expressions and distributions in renal LN patients' biopsies. The frequencies of two SNP in the TLR-9 gene and one in the TLR-5 gene was examined in 106 SLE patients (among them 37 LN patients) and in 200 matched controls by polymerase chain reaction-restriction fragment-length polymorphisms (PCR-RFLP) analysis. TLR-9 and TLR-5 expressions were assessed by reverse transcription (RT)-PCR and immunohistochemistry carried on LN renal biopsies compared to healthy renal tissue. A significant genotypic and allelic association was revealed between TLR-9-rs352140 and both SLE and LN (P < 0·05). The TLR-9 transcript level was significantly higher in LN biopsies compared to control (P < 0·05). This increase was observed histochemically in the tubulointerstitial compartment. TLR-9 was detectable in LN glomeruli patients but not in normal control glomeruli. No allelic nor genotype association was found with TLR-5-rs5744168 in SLE. but the T allele and the TT genotype were raised significantly in the LN group (P < 0·05). A significant increase in TLR-5 gene expression in LN biopsies, which contrasted with normal kidneys (P < 0·05), was confirmed by an intense and diffuse staining for TLR-5 only in LN tubules (P < 0·05). Our data show that TLR-5 and TLR-9 are susceptible genes to LN and that their expression is dysregulated in LN patients' kidneys, supporting a role of these mediators in the pathogenesis of LN.

TLR4 rs41426344 increases susceptibility of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) in a central south Chinese Han population

BACKGROUND

The aim of the study was to determine whether polymorphisms in toll-like receptor 4 (TLR4) confer susceptibility to rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) in a central south Chinese Han population.

METHODS

Genotyping for six well studied polymorphisms (rs4986790, rs4986791, rs10759932, rs41426344, rs11536889 and rs7873784) in TLR4 gene were conducted in 1074 unrelated patients with RA and 1692 healthy control subjects, as well as in 217 unrelated patients with JIA and 378 healthy control subjects using direct sequencing technique. Comparisons between cases and controls in alleles, genotypes and haplotypes were carried out using Fisher's exact test.

RESULTS

Significant genetic associations were detected between the 3'UTR rs41426344C and RA (p < 0.001, p _adj < 0.001, OR = 2.24) and JIA (p < 0.001, p _adj < 0.001, OR = 2.05). In addition, rs4986790G was found to be significantly associated with the susceptibility for RA (p = 0.005, p _adj = 0.03, OR = 3.43), but not for JIA (p = 0.06, p _adj = 0.36, OR = 2.65). Furthermore, significant increasing in the distributions of haplotypes H4 and H10 in RA (H4: p = 0.001, OR = 1.13; H10: p = 0.001, OR = 1.15) and JIA (H4: p = 0.04, OR = 2.06; H10: p = 0.02, OR = 2.47) were also found. Moreover, the frequency of rs41426344C significantly increased in RF-positive and anti-CCP positive subjects both in RA (RF⁺: p <0.0001, OR = 2.33; anti-CCP⁺: p =0.008, OR = 2.79) and JIA (RF⁺: p =0.02, OR = 2.91; anti-CCP⁺: p = 0.02, OR = 2.78).

CONCLUSIONS

Our study suggested that rs41426344 and rs4986790 of TLR4 might contribute to RA, and rs41426344 might contribute to JIA pathogenesis in central south Chinese Han population.

Association between Toll-Like Receptor 4 Polymorphisms and Systemic Lupus Erythematosus Susceptibility: A Meta-Analysis

Family aggregation was observed among systemic lupus erythematosus (SLE) cases, suggesting the genetic factor may contribute to the susceptibility. Toll-like receptors (TLR) play key role in human immune system; in order to gain better insight on the association between TLR4 polymorphisms and SLE risk, a meta-analysis was conducted. In total 4 case-control studies have been included, involving 503 SLE cases and 636 healthy controls. The association between TLR4 polymorphisms and SLE risk was evaluated by calculating pooled odd ratio (OR) and its 95% confidential interval (CI). The Q-test and I² statistic were used to estimate the degree of heterogeneity. Publication bias among enrolled studies was examined by using Egger's test and Begg's test. Overall, there was no evidence of positive association between SLE risk and D299G and T399I polymorphisms in TLR4. The meta-analysis reported a null association between TLR4 polymorphisms and SLE risk in included study populations, but the role of TLR4 polymorphisms in developing SLE among other populations remains undetermined. Moreover, some laboratory studies still discovered the involvement of TLR4 in SLE process. Therefore, the association between TLR4 polymorphisms and SLE risk requires further investigation both in laboratory and in epidemiological efforts.

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.

Toll-like receptors: potential targets for lupus treatment

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by the loss of tolerance to self-nuclear antigens. Accumulating evidence shows that Toll-like receptors (TLRs), previously proven to be critical for host defense, are implicated in the pathogenesis of autoimmune diseases by recognition of self-molecules. Genome-wide association studies, experimental mouse models and clinical sample studies have provided evidence for the involvement of TLRs, including TLR2/4, TLR5, TLR3 and TLR7/8/9, in SLE pathogenesis. A number of downstream proteins in the TLR signaling cascade (such as MyD88, IRAKs and IFN-α) are identified as potential therapeutic targets for SLE treatment. Numerous antagonists targeting TLR signaling, including oligonucleotides, small molecular inhibitors and antibodies, are currently under preclinical studies or clinical trials for SLE treatment. Moreover, the emerging new manipulation of TLR signaling by microRNA (miRNA) regulation shows promise for the future treatment of SLE.

Toll-like receptors TLR4 (Asp299Gly and Thr399Ile) and TLR2 (Arg677Trp and Arg753Gln) gene polymorphisms in end-stage renal disease patients on peritoneal dialysis

BACKGROUND

Toll-like receptors (TLRs), expressed on cells of the innate immune system, are the first line of host defense. Recognition of bacterial pathogens by the peritoneum is mediated in part by TLR. In this study, we investigated the role of TLR4 (Asp299Gly and Thr399Ile) and TLR2 (Arg677Trp and Arg753Gln) gene polymorphisms in end-stage renal disease (ESRD) patients on peritoneal dialysis (PD).

METHOD

A total of 100 ESRD patients on PD and 150 healthy controls were enrolled in the study. The patients were divided into two groups: ESRD patients on PD with peritonitis (n = 38) and without peritonitis (n = 62). Genotyping of TLR4 (Asp299Gly and Thr399Ile) and TLR2 (Arg677Trp and Arg753Gln) genes were performed by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP).

RESULTS

Heterozygous variant of TLR4 (Thr399Ile) Thr/Ile genotype showed significant association with both groups of patients (patients with and without peritonitis) with no difference between the groups. Overall, TLR4 (Thr399Ile) Thr/Ile genotype demonstrated an association with ESRD on PD (OR 3.9). Further, TLR4 (Thr399Ile) polymorphism showed significant association with PD patients having two or more episodes of peritonitis compared to patients with no peritonitis. No such association of increased risk of ESRD was observed with TLR4 (Asp299Gly) Asp/Gly genotype and TLR2 polymorphisms. Haplotype frequencies, Gly/Ile and Asp/Ile, conferred 2.46- and 4.62-fold increased risk of ESRD, respectively.

CONCLUSIONS

TLR4 Thr399Ile genotype was associated with ESRD patients on PD; however, the genotype frequency was similar in PD patients with and without peritonitis.

Investigation of Toll-Like Receptor-2 (2258G/A) and Interferon Gamma (+874T/A) Gene Polymorphisms among Infertile Women with Female Genital Tuberculosis

BACKGROUND

Toll-like receptor 2 (TLR2) and interferon-gamma (IFN-γ) coordinate with a diverse array of cellular programs through the transcriptional regulation of immunologically relevant genes and play an important role in immune system, reproductive physiology and basic pathology. Alterations in the functions of TLR2 2258G (guanine)/ A, IFN-γ (+874T/A) and signalling molecules that result from polymorphisms are often associated with susceptibility or resistance, which may, in turn, establish the innate host response to various infectious diseases. Presently, we proposed to investigate the risk of common single nucleotide polymorphism (SNP) of TLR2 and IFN-γ genes, for their effect on infertility in women with female genital tuberculosis (FGTB) and healthy women as controls.

METHODOLOGY/PRINCIPAL FINDINGS

Genotyping of TLR2 and IFN-γ gene polymorphisms was performed by amplification refractory mutation system multi-gene/multi-primer polymerase chain reaction followed by restriction fragment length polymorphism in 175 FGTB patients and 100 healthy control women (HCW). The TLR2 polymorphism [adenine (A) allele] was observed in 57.7 and 58.0% of FGTB patients and HCW, respectively. The IFN-γ (+874T/A) polymorphism (A allele) was significant in 74.3 and 71.0% of FGTB patients and HCW, respectively, while the odds ratios for the AA and TA genotypes for predisposition of FGTB were found to be 0.304 and 1.650 in HCW, respectively. The SNP of TLR2 was not associated with FGTB but the SNP of IFN-γ was found to be associated with mycobacteria infections and to induce infertility.

CONCLUSIONS/SIGNIFICANCE

At present, we hypothesize that infertile women with FGTB and HCW without tuberculosis (TB) have identical frequency of TLR variants, which may be adequate in the production of IFN-γ in response to Mycobacterium tuberculosis infections. Thus, the study appears to be the first of its kind reporting a mutation in the IFN-γ gene [+874 T (thymine) to A] responsible for susceptibility to TB infections and further inducing infertility.

Associations of toll-like receptor (TLR)-4 single nucleotide polymorphisms and rheumatoid arthritis disease progression: an observational cohort study

OBJECTIVE

To examine the associations of toll-like receptor (TLR)-4 single nucleotide polymorphisms (SNPs) with disease progression in rheumatoid arthritis (RA).

METHODS

A total of 1188 RA patients were genotyped for TLR4 SNPs (rs1927911, rs11536878, and rs4986790). Measures of disease activity were examined, including Disease Activity Score-28 (DAS28), Multidimensional Health Assessment Questionnaire (MD-HAQ), Clinical Disease Activity Index (CDAI), and Simplified Disease Activity Index (SDAI). Genetic associations with these longitudinal measures were examined using generalized estimating equations in both univariate and multivariate analyses. Analyses were then stratified by antigen specific anti-citrullinated peptide antibody (ACPA) status including antibody to citrullinated fibrinogen and citrullinated histone H2B.

RESULTS

Disease activity measures progressed less over time in the homozygous minor allele group of rs1927911 including DAS28 (p<0.001), CDAI (p=0.008), and MD-HAQ (p=0.015) in univariate analysis and DAS28, CDAI and SDAI in multivariate analysis. Disease activity progression among those homozygous for the minor allele tended to be lower in the groups with positive ACPA though major differences by autoantibody status were not identified. There were no associations of TLR4 rs11536878 and rs4986790 SNPs with RA disease activity progression.

CONCLUSIONS

In this population, TLR4 rs1927911 genotypes are associated with disease activity independent of other covariates.

Association of Toll like receptor Asp299Gly with rheumatoid arthritis risk: a systematic review of case-control studies and meta-analysis

OBJECTIVE

Rheumatoid arthritis (RA) is thought to be triggered by various genetic and environmental factors. Few human epidemiologic studies demonstrated that single nucleotide polymorphisms (SNPs) in Toll-like receptor (TLR) genes are associated with RA. We aimed to evaluate the effects of TLR polymorphisms on the risk of RA pathogenesis by using a meta-analysis approach.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, a systematic search and meta-analysis of the literature was conducted. We screened the medical literature based on keywords search in MEDLINE and EMBASE 'Toll-like receptor', 'polymorphism', and rheumatoid arthritis. Meta-analyses were performed under the random-effects model by using: (1) recessive, (2) homozygous, (3) dominant, (4) codominant and allele contrast models.

RESULTS

A total of 3086 cases and 3756 controls in nine studies were included in the meta-analysis. Association between TLR4 Asp299Gly and RA risk was marginally significant [OR = 0.856 (95% CI, 0.716-1.022); P = 0.086] in the homozygous model. AA and GG homozygote genotypes tended to be significant protective factors against RA risk.

CONCLUSION

Our overall analyses indicated that TLR4 Asp299Gly polymorphism might contribute to RA pathogenesis.

Susceptibility to SLE in South Indian Tamils may be influenced by genetic selection pressure on TLR2 and TLR9 genes

INTRODUCTION

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with complex etiology. Genetics plays an important role in lupus pathogenesis through its influence on clinical and autoantibody phenotype of the disease. Toll like receptors (TLR) recognize molecular patterns of pathogens and activate the innate immune system. Their ability to identify nucleic acids makes them suitable candidates for investigation of their role in lupus pathogenesis. Hence, this study was carried out to analyze the G to A and C to T transitions in TLR2 and TLR9 genes respectively and to test their association with lupus susceptibility, clinical and autoantibody phenotypes in South Indian Tamils.

METHOD

Three hundred SLE patients fulfilling ACR 2012 criteria for SLE and 460 age, sex similar, ethnicity matched controls were recruited as cases and controls. TLR2 (R753Q) and TLR9 (-1237C/T) polymorphisms were analyzed by real time PCR.

RESULTS

The TLR2 gene remained monomorphic in patients and controls, the frequency of the homozygous wild type allele being 100% and 99.6% respectively. Hence, it did not confer susceptibility to SLE. The more frequent T allele of TLR9 gene conferred a significant risk to develop SLE (p=0.011, OR 1.69, 95% CI 1.1-2.6). Both the polymorphisms did not influence clinical or autoantibody phenotype of the disease.

CONCLUSION

Prevailing endemic infections in the Indian subcontinent may have exerted a selection pressure resulting in TLR2 gene remaining monomorphic and the TLR9 adapting to a mutation for its increased expression. These may have an additive effect in the presence of other genetic and environmental risk factors to confer susceptibility to SLE in South Indian Tamils.

Polymorphisms of Toll-like receptors 2 and 4 in chronically infected hepatitis C patients from north-east Croatia

Chronic infection with hepatitis C virus (HCV) is caused by an inadequate immune response. Experimental data suggest that the impaired activation of Toll-like receptors (TLRs) 2 and 4 contributes to chronic infection. We assessed the distribution of three single-nucleotide polymorphisms (SNPs) in the TLR2 (Arg753Gln) and TLR4 (Asp299Gly/Thr399Ile) genes in individuals from north-east Croatia and their effect on the outcome of antiviral therapy. The study consisted of 60 chronically infected patients and 40 healthy subjects. TLR polymorphisms were determined by the PCR-based melting curve analysis. HCV genotyping was performed using the Linear Array Hepatitis C Virus Genotyping Test. Thirty-three patients were treated with standard interferon and ribavirin therapy, and their viral load was evaluated at weeks 28 and 53 after the beginning of therapy. The majority of chronic infections were caused by genotype 1 (77%), followed by genotypes 3 (15%) and 4 (7%). Patients with genotype 1 had higher viral loads than patients infected with other genotypes (P = 0.0428). Healthy individuals and patients with chronic infection had similar frequencies of TLR2-Arg753Gln and TLR4-Asp299Gly/Thr399Ile SNPs. Heterozygous and homozygous TLR4-Asp299Gly/Thr399Ile polymorphisms correlated with higher viral loads and delayed responses to antiviral therapy. We have provided the first evidence that TLR4 polymorphisms influence the success of antiviral therapy in our region. This suggests that therapeutic strategies should be adjusted not only according to HCV genotype but also to individual TLR polymorphism(s).

Association of TLR4 (D299G, T399I), TLR9 -1486T>C, TIRAP S180L and TNF-α promoter (-1031, -863, -857) polymorphisms with risk for systemic lupus erythematosus among South Indians

The rationale of this case-control study was to explore the association of Toll-like receptor 4 (TLR4) D299G, TLR4 T399I, TLR9 -1486 T>C, TIR-domain-containing adaptor protein (TIRAP) S180 L and tumor necrosis-α (TNF-α) promoter polymorphisms with susceptibility and phenotypic heterogeneity of systemic lupus erythematosus (SLE). PCR-RFLP, real-time PCR was used for the genetic analysis and expression studies and ELISA was used for the determination of specific autoantibodies. TLR4 D299G was associated with the risk for SLE (OR: 1.57, 95% CI: 1.08-2.28), while the TNF-α (-1031, -863, -857) CCC haplotype conferred protection. TLR4 and TIRAP polymorphisms were associated with reduced expression of HLA-DR. The presence of TLR4 and TLR9 polymorphisms increases the MHC2TA expression, while TIRAP polymorphism was associated with reduced expression. TLR4 D299 G showed an inverse association with pulmonary hypertension. TLR 4 T399I and TLR9 -1486 T>C showed a positive association with seizures and photosensitivity, respectively. TIRAP S180 L showed a positive association with alopecia and malar rashes, while an inverse association with psychosis was observed. TLR4 T399I (r = 0.14, p = 0.05) and TIRAP S180 L (r = 0.15, p = 0.03) showed a positive association with anti-Ro antibodies. On the other hand, TLR9 -1486 T>C showed an inverse association with anti-La antibodies (r = -0.20, p = 0.006). To conclude, TLR4 D299G increases the risk for SLE, while TNF-α CCC haplotype reduces the risk for SLE. All these polymorphisms contribute toward phenotypic heterogeneity. TLR4 T399I, TLR9 -1486 T>C and TIRAP S180 L influence specific autoantibody production in SLE.

Toll-like receptor 4 gene polymorphism 1196 C/T does not influence the risk of neuropsychiatric systemic lupus erythematosus in Polish population – a preliminary report

Objective

Recent data indicate that Toll-like receptors (TLRs) participate in various neuropathologic conditions, including ictogenesis, myelin disruptions associated with chronic alcohol abuse, behavioral and cognitive dysfunctions associated with alcohol-induced neuroinflammatory damage, and activation of microglia to reduce amyloid β deposits. As seizures and depression are well known neuropsychiatric syndromes in systemic lupus erythematosus (SLE) the aim of the study was to investigate whether TLR4 gene polymorphism 1196C/T (rs4986791, Thr399Ile) was a candidate for susceptibility of development of neuropsychiatric systemic lupus erythematosus (NPSLE).

Methods

The study covered 60 patients with SLE and 100 healthy individuals. TLR4 1196C/T genotyping was performed by real-time polymerase chain reaction with the SimpleProbe.

Results

The SLE group comprised 86.7% of patients with wild-type homozygotes CC and 13.3% heterozygotes CT and no homozygotes TT. The control group consisted of 85% wild-type homozygotes CC, 15% heterozygotes CT and no homozygotes TT. The frequencies of genotype and allele distribution in SLE patients did not differ significantly from those of the control subjects. The probability of describing the possible risk of SLE imputed to genotype did not significantly differ in comparison with the healthy individuals ( p = 0.77, odds ratio = 0.87, 95% confidence interval 0.34–2.19). A significant genotype association of genotype CC with arthritis was found in SLE patients ( p = 0.02). It was further confirmed by a significant association of a dominant allele C with arthritis ( p = 0.02). No association between CC and CT genotypes of TLR4 1196C/T and NPSLE was found. Allele distribution of TLR4 1196C/T also was not associated with NPSLE. No other significant differences were found in genotype and allele frequencies regarding clinical manifestation of SLE patients.

Conclusion

In the Polish population of SLE patients, 1196C/T polymorphism of TLR4 gene does not increase the risk of development of NPSLE; however, genotype CC and a dominant allele C is associated with arthritis in the course of SLE.

Association between TLR4 and TLR9 gene polymorphisms with development of pulmonary tuberculosis in Zahedan, southeastern Iran

Some evidence suggests that a variety of genetic factors contribute to development of the tuberculosis (TB). TLR4 and TLR9 have been proposed as susceptibility genes for TB. This study was performed in 124 newly diagnosed TB cases and 149 healthy controls in a TB-endemic region of Iran. The TLR4 genes Asp299Gly, Thr399Ile, and TLR9 gene T-1486C polymorphisms were amplified by polymerase chain reaction (PCR) and then detected by PCR-restriction fragment length polymorphism (RFLP). The frequencies of the mutant alleles of TLR4 Arg299Gly, Thr399Ile, and TLR9 T-1486C polymorphisms were 0.8 versus 0.1, 5.6 versus 3, and 28.6 versus 25.2 in patients and controls, respectively, that were not significant. The synergic effect of TI,II/CC genotypes for TLR4 Thr399Ile and TLR9 T-1486C polymorphisms showed increased risk of PTB susceptibility. In conclusion, no significant relation was found between TLR4 and TLR9 polymorphisms alone and PTB. However, synergic effects of TLR4 Thr399Ile and TLR9-1486T/C polymorphisms might increase risk of PTB.

Polymorphisms of Toll-like receptor-4 and CD14 in systemic lupus erythematosus and rheumatoid arthritis

Background

Toll-like receptor 4 (TLR4) and its co-receptor CD14 play a major role in innate immunity by recognizing PAMPs and signal the activation of adaptive responses. These receptors can recognize endogenous ligands mainly auto-antigens. In addition, TLR4 (Asp299Gly) and CD14 (C/T -159) polymorphisms (SNPs) may modify qualitatively and/or quantitatively their expression. Therefore, they could be implied in autoimmune diseases and can influence both susceptibility and severity of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

Patients and methods

TLR4 (Asp299Gly) and CD14 (C/T -159) SNPs were genotyped using polymerase chain reaction (PCR)-RFLP in 127 SLE patients, 100 RA patients, and 114 healthy controls matched in age and gender.

Results

CD14*T allele was significantly more frequent in SLE patients (0.456) comparatively to controls (0.355), p = 0.02 OR (95% CI) = 1.53 [1.04-2.24]. In RA patients, the higher frequency of CD14*T allele (0.405) failed to reach significance, p = 0.28. Investigation of the TLR4 (Asp299Gly) SNP showed no significant association neither with SLE nor with RA.

Analysis of these SNPs according to clinical and biological features showed a significant higher frequency of arthritis in SLE patients carrying CD14*T/T genotype (92%) comparatively to those with C/C and C/T genotypes (72.5%), p = 0.04. Moreover, SLE patients carrying CD14*T/T/TLR4*A/A haplotype had significantly more arthritis (91.3%) than the rest of SLE group (73%), p = 0,044 and confirmed by multivariable analysis after adjustment according to age and gender, p = 0.01.

Conclusion

The CD14 (-159)*T allele seems to be associated with susceptibility to SLE and arthritis occurrence.

TLR-4 and VEGF polymorphisms in chronic periaortitis

Objective

Chronic periaortitis (CP) is a rare disease that is characterised by fibro-inflammatory tissue surrounding the abdominal aorta and has both non-aneurysmal (idiopathic retroperitoneal fibrosis [IRF]) and aneurysmal forms (inflammatory abdominal aortic aneurysm [IAAA]). We investigated whether toll-like receptor 4 (TLR-4) and vascular endothelial growth factor (VEGF) polymorphisms were associated with susceptibility to, and the clinical features of CP.

Methods

One hundred and two CP patients and 200 healthy controls were molecularly genotyped for TLR-4 gene polymorphism (+896 A/G) (rs4986790), VEGF mutations +936 C/T (rs3025039) and −634 C/G (rs2010963), and an 18 base pair (bp) insertion/deletion (I/D) polymorphism at −2549 of the VEGF promoter region. The patients were grouped on the basis of the type of CP (IRF or IAAA), and the presence or absence of established atherosclerotic disease (ischemic heart disease, cerebrovascular disease, and peripheral arterial disease).

Results

There were no significant differences in the distribution of the studied polymorphisms between the patients and controls. However, carriage of the +936 T allele was significantly more frequent in the patients with IRF than in those with IAAA (26.5% vs 5.3%; p = 0.046; OR 6.49 [95% CI 0.82–51.54]). There were significantly more carriers of the I allele among the patients with ureteral obstruction (83.8% vs 58.8%; p = 0.006; OR 3.63 [95% CI 1.42–9.28]) and those who received conservative treatment (48.5% vs 23.5%; p = 0.015; OR 3.06 [95% CI 1.22–7.721]) than among those without, and II homozygosity was significantly more frequent in the patients with deep vein thrombosis than in those without (30.4% vs 11.7%, p = 0.031; OR 3.31 [95% CI 1.07–10.21]).

Conclusion

The VEGF +936 C/T polymorphism may be associated with an increased risk of developing the non-aneurysmal IRF form of CP. Carriers of the I allele and II homozygosity are respectively at increased risk of developing ureteral obstruction and deep vein thrombosis.

Surface expression and genotypes of Toll-like receptors 2 and 4 in patients with juvenile idiopathic arthritis and systemic lupus erythematosus

BACKGROUND

Chronic arthritis is a common feature of juvenile idiopathic arthritis (JIA) and systemic lupus erythematosus (SLE). It was subsequently discovered that Toll-like receptors (TLRs) are able to upregulate cytokine production in response to endogenous ligands released after tissue damage, suggesting that TLRs can maintain an inflammatory response even in absence of pathogen. Thus, TLRs may contribute to increased inflammation in JIA and SLE patients. The aim of this study was to investigate the role of TLRs in JIA and SLE. We examined the in vivo expression and polymorphisms of TLR2 and TLR4 in peripheral monocytes of patients with JIA and SLE during active and inactive disease phases.

METHODS

This single center cohort study consisted of JIA and SLE affected children and control subjects. TLR2 and TLR4 protein expression on CD14+ monocytes was examined by flow cytometry. TLR2 and TLR4 genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism method (RFLP-PCR).

RESULTS

A significant reduction in the level of TLR4 expression (p ≤ 0.001) was observed on monocytes of patients with JIA and SLE compared with that of healthy control subjects. There was no correlation between the TLR2 or TLR4 genotypes and the observed differential TLR protein expression on monocytes.

CONCLUSIONS

To conclude, our observations suggest involvement of investigated TLRs in the pathogenesis of JIA and SLE. It still remains to be elucidated whether reduced TLR4 expression is cause of chronic arthritis or a result of some feedback loop.

Allelic variants in TLR10 gene may influence bilateral affectation and clinical course of Meniere's disease

Toll-like receptors trigger the innate immune response by activating various cell types such us macrophages and lymphocytes. We genotyped SNV of TLR3, TRL7, TLR8 and TLR10 in 863 Spanish and 150 Italian patients with Meniere's disease (MD) and 1,013 controls by using Taqman assays. Real-Time qPCR was used to measure the expression level of TLR10 in peripheral blood leukocytes. The overall dataset showed that the C allele and the CC genotype of rs11096955 in TLR10 gene were more commonly observed in controls than patients (corrected p = 1 × 10(-3), OR = 0.68 [95 % confidence interval, 0.54-0.84] for CC genotype; corrected p = 1.5 × 10(-5), OR = 0.75 [0.66-0.85] for allele C). Moreover, the CC genotype was more frequent in patients with uni- (19 %) than bilateral sensorineural hearing loss (SNHL) (13 %). Logistic regression demonstrated that the time since the onset of MD, Tumarkin crises, hearing stage and rs11096955 were independent factors influencing the risk of bilateral SNHL. In addition, rs11096955 influenced hearing loss progression in patients with bilateral MD. No change in expression of TLR10 was observed according to CC, CA or AA genotypes. Our data suggest that allelic variants of TLR10 gene may influence the susceptibility and time-course of hearing loss of MD in the European population.

Toll-like receptor polymorphisms and rheumatoid arthritis: a systematic review

The aim of this study was to determine whether toll-like receptor (TLR) polymorphisms confer susceptibility to rheumatoid arthritis (RA) and influence the clinical characteristics of RA. The authors conducted a systematic review on associations between TLR polymorphisms and RA susceptibility and clinical findings. Meta-analysis was performed if at least three comparisons of an issue were available. A total of 14 studies were included in this systematic review, which included European and Asian studies. Meta-analysis of five European studies showed no association between the TLR4 Asp299Gly (rs4986790) polymorphism and RA (OR for the minor allele = 0.907, 95% CI = 0.755-1.088, p = 0.291). Furthermore, none of these studies found any association between the polymorphism and clinical characteristics. A significant difference between TLR9 rs187084 allele frequencies in RA patients and controls was found in one Turkish study (p = 0.003), and a moderate association between RF positivity and TLR8 rs5741883 was found in an European study (p = 0.001). The numbers of guanine-thymine [(GT)n] repeats in intron II of the TLR2 gene were found a significantly higher S-allele frequency in Korean patients with RA than in controls (30.3 vs. 23.0 %, p = 0.03). This meta-analysis shows lack of an association between the TLR4 Asp299Gly polymorphism and RA. However, our finding suggests the possibility that TLR polymorphisms are associated with the development and clinical characteristics of RA. Because of a paucity of data of the TLR polymorphisms, case-control studies are required to determine whether TLR2, 4, 8, 9 polymorphisms contribute to RA susceptibility or severity in more than 2,000 patients and controls.

Analysis of TLR4 and TLR2 polymorphisms in inflammatory bowel disease in a Guangxi Zhuang population

AIM: To study the polymorphisms of toll-like receptor 4 (TLR4) gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp and susceptibility to inflammatory bowel disease (IBD) in the Zhuang population from Guangxi, China.

METHODS: A case-control study was performed from February 2007 to October 2011 which included 146 Zhuang patients with IBD in the experimental group and 164 healthy Zhuang subjects who acted as the control group. All patients and healthy subjects were from the Guangxi Zhuang Autonomous Region of China. Genomic DNA was extracted from intestinal tissue by the phenol chloroform method. TLR4 gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp were amplified by polymerase chain reaction (PCR), and then detected by PCR-restriction fragment length polymorphism (RFLP).

RESULTS: The TLR4 gene Asp299Gly was digested using Nco I restriction enzyme, and a single band of 249 bp was observed which showed that it was a wild type (AA). The TLR4 gene Thr399Ile was digested using Hinf Irestriction enzyme and only the wild type (CC) was detected. In addition, the TLR2 gene Arg677Trp was digested using Aci I restriction enzyme and only the wild type (CC) was detected. The TLR2 gene Arg753Gln was digested using Pst I restriction enzyme. Only the wild type (GG) as a single band of 254 bp was observed during RFLP. Overall, no heterozygous or homozygous single nucleotide polymorphism mutations were found in patients with Crohn’s disease and ulcerative colitis both in the TLR4 gene Asp299Gly, Thr399Ile and the TLR2 gene Arg677Trp, Arg753Gln in the Zhuang population from the Guangxi Zhuang Autonomous Region of China.

CONCLUSION: The TLR4 gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp polymorphisms may not be associated with IBD in the Zhuang population from the Guangxi Zhuang Autonomous Region of China.

The presence of anti-LPS antibodies and human serum activity against Proteus mirabilis S/R forms in correlation with TLR4 (Thr399Ile) gene polymorphism in rheumatoid arthritis

OBJECTIVES

Proteus mirabilis strains are human pathogens responsible for urinary tract infections, which may also be involved in rheumatoid arthritis (RA).

DESIGN AND METHODS

We determined whether the binding site of anti-LPS antibodies on the O-polysaccharide part of P. mirabilis LPS correlates with the level of TLR4 (Thr399Ile) gene polymorphism in the sera of RA patients. We investigated the deposition of C3d and C5b complement components on the P. mirabilis LPS. The ELISA method used in this study was optimized with LAL test and laser interferometry.

RESULTS

Depending on LPS P. mirabilis used in these studies, the amount of antibodies in RA patients sera varied. We did not observe a correlation between anti-LPS antibodies binding and the level of TLR4 (Thr399Ile) gene polymorphism. We found that the lower complement components deposition by O49 in contrast to O9 LPS correlates with its reduced sensitivities to human complement-mediated killing.

CONCLUSION

The immunological response against P. mirabilis LPS might play a role in rheumatoid arthritis.

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.

Lack of association between TLR4 rs4986790 polymorphism and risk of cardiovascular disease in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with increased cardiovascular (CV) mortality. Toll-like receptor-4 (TLR4) activates the innate immune response via NF-kB pathway and mitogen-activated protein kinase signaling, leading to expression of proinflammatory cytokines and chemokines. The G allele of TLR4 rs4986790 (+896A>G, Asp299Gly) gene polymorphism has been implicated in reduction of risk of atherosclerosis. In this study, 1481 RA patients fulfilling the 1987 American College of Rheumatology (ACR) criteria were genotyped for the rs4986790 TLR4 variant to determine the influence of this variant in the risk of CV events in these patients. Also, HLA-DRB1 status was determined using molecular based methods. Moreover, potential influence of rs4986790 variant in the development of subclinical atherosclerosis was assessed in a subgroup of RA patients with no history of CV events by the measurement of surrogate markers of subclinical atherosclerosis. No statistically significant differences in allele or genotype frequencies for the rs4986790 variant between RA patients who experienced CV events or not were found. Likewise, no significant association between this gene variant and any of the surrogate markers of subclinical atherosclerosis was found. In summary, results in our study do not support the hypothesis that the rs4986790 (+896A>G, Asp299Gly) TLR4 variant may influence predisposition for subclinical atherosclerosis and clinically evident CV disease in RA patients.

The (-1486T/C) promoter polymorphism of the TLR-9 gene is associated with end-stage knee osteoarthritis in a Chinese population

Based on the recent observation that Toll-like receptors (TLRs) may be involved in the pathogenesis of osteoarthritis (OA) we explored the possibility that human TLR gene polymorphisms are associated with OA. Two separate populations were studied in a two-stage case-control study with a total of 503 OA patients and 428 healthy controls. The TLR-2, TLR-4, and TLR-9 genotypes were assessed by real-time polymerase chain reaction. Our data demonstrated a lack of association among TLR-2, TLR-4, and TLR-9 (T-1237C) polymorphisms and the risk of developing OA in both stages of the study. T-1486C was significantly associated with OA in both populations with G1635A of TLR-9 gene was found to be significantly associated with OA when the two populations were combined. Stratifying the samples by K-L score there were significant differences in the genotype of the TLR-9 T-1486C and G1635A between OA of the knee grade 4 and controls. In haplotype analyses, the haplotype TTG and TTA revealed higher risk of OA and TCA confers a lower risk of OA in combined population. The present results demonstrate that TLR-9 polymorphisms, in particular T-1486C is significantly associated with OA. TLR-9 gene polymorphisms may play a role in the etiology of knee OA.

Toll-like receptors are potential therapeutic targets in rheumatoid arthritis

Toll-like receptors (TLRs) are found on the membranes of pattern recognition receptors and not only play important roles in activating immune responses but are also involved in the pathogenesis of inflammatory disease, injury and cancer. Furthermore, TLRs are also able to recognize endogenous alarmins released by damaged tissue and necrosis and/or apoptotic cells and are present in numerous autoimmune diseases. Therefore, the release of endogenous TLR ligands plays an important role in initiating and driving inflammatory diseases. Increasing data suggest a role for TLR signaling in rheumatoid arthritis, which is an autoimmune disease. Although their involvement is not comprehensively understood, the TLRs signaling transducers may provide potential therapeutic targets.

Genetic variants in toll-like receptors are not associated with rheumatoid arthritis susceptibility or anti-tumour necrosis factor treatment outcome

Background

Several studies point to a role of Toll-like receptors (TLRs) in the development of rheumatoid arthritis (RA). We investigated if genetic variants in TLR genes are associated with RA and response to tumour necrosis factor blocking (anti-TNF) medication.

Methodology and Principal Findings

22 single nucleotide polymorphisms (SNPs) in seven TLR genes were genotyped in a Dutch cohort consisting of 378 RA patients and 294 controls. Significantly associated variants were investigated in replication cohorts from The Netherlands, United Kingdom and Sweden (2877 RA patients and 2025 controls). 182 of the Dutch patients were treated with anti-TNF medication. Using these patients and a replication cohort (269 Swedish patients) we analysed if genetic variants in TLR genes were associated with anti-TNF outcome. In the discovery phase of the study we found a significant association of SNPs rs2072493 in TLR5 and rs3853839 in TLR7 with RA disease susceptibility. Meta-analysis of discovery and replication cohorts did not confirm these findings. SNP rs2072493 in TLR5 was associated with anti-TNF outcome in the Dutch but not in the Swedish population.

Conclusion

We conclude that genetic variants in TLRs do not play a major role in susceptibility for developing RA nor in anti-TNF treatment outcome in a Caucasian population.

Toll-like receptor 4 signaling in liver injury and hepatic fibrogenesis

Toll-like receptors (TLRs) are a family of transmembrane pattern recognition receptors (PRR) that play a key role in innate and adaptive immunity by recognizing structural components unique to bacteria, fungi and viruses. TLR4 is the most studied of the TLRs, and its primary exogenous ligand is lipopolysaccharide, a component of Gram-negative bacterial walls. In the absence of exogenous microbes, endogenous ligands including damage-associated molecular pattern molecules from damaged matrix and injured cells can also activate TLR4 signaling. In humans, single nucleotide polymorphisms of the TLR4 gene have an effect on its signal transduction and on associated risks of specific diseases, including cirrhosis. In liver, TLR4 is expressed by all parenchymal and non-parenchymal cell types, and contributes to tissue damage caused by a variety of etiologies. Intact TLR4 signaling was identified in hepatic stellate cells (HSCs), the major fibrogenic cell type in injured liver, and mediates key responses including an inflammatory phenotype, fibrogenesis and anti-apoptotic properties. Further clarification of the function and endogenous ligands of TLR4 signaling in HSCs and other liver cells could uncover novel mechanisms of fibrogenesis and facilitate the development of therapeutic strategies.

Toll-like receptor signaling pathways--therapeutic opportunities

Toll-like receptors (TLRs) are transmembrane proteins acting mainly as sensors of microbial components. Triggering TLRs results in increased expression of multiple inflammatory genes, which then play a protective role against infection. However, aberrant activation of TLR signaling has a significant impact on the onset of cancer, allergy, sepsis and autoimmunity. Various adaptor proteins, including MyD88, IRAKs, TIRAP, TRIF, and TRAM, are involved in specific TLR signaling pathways. This article reviews the role of these molecules in TLR signaling, and discusses the impact of this pathway on various disease scenarios. Given their important role in infectious and non-infectious disease settings, TLRs and their signaling pathways emerge as attractive targets for therapeutics.