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

Abstract

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 with 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 direct sequencing. The odds ratios (ORs) and 95% confidence intervals (CIs) were evaluated using a standard logistic regression analysis.

Results:

No significant associations were observed under the allelic, dominant, or recessive models for TLR-1 rs5743610, TLR-2 rs5743708, TLR-4 rs4986790 and rs4986791, and TLR-6 rs5743810 polymorphisms and RA risk (all p > 0.05). However, significant associations were detected under the allelic, dominant, and recessive models for 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, 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 marker may be associated with RF and the anti-CCP antibody of RA in the Chinese Han population.

Introduction

Rheumatoid arthritis (RA) is a chronic, aggressive, and systemic autoimmune disease (Gallacher, 2015). The incidence of RA varies by region and race, and the prevalence of RA in China is about 0.3-0.5%. Also, the RA prevalence in females is three times than that in males (Yu et al., 2018). Epidemiological studies have found that the incidence of RA is characterized by familial aggregation and co-twin disease, and the heritability of RA in identical twins is 53-65% (Alarcón-Segovia et al., 2005; Kuo et al., 2017). Although the etiology of RA is undetermined, a number of genetic components have been established (Karlson et al., 2013).

Toll-like receptors (TLRs) are the specific type I transmembrane receptors and pathogenic pattern recognition receptors in the natural immune system, and play an important role in inflammation, cell signal transduction, and apoptosis (Netea et al., 2006; Ospelt and Gay, 2010). It has been found that TLRs, especially TLR2 and TLR4, on the cell surface play a key role in the development of RA (Ruckdeschel et al., 2004). Studies showed that the expressions of TLR-2, -3, -4, and -7 in synovial tissues, synovial fibroblasts, peripheral blood monocytes, and CD14⁺ macrophages in synovial fluid of RA patients significantly increased (Iwahashi et al., 2004; Thwaites et al., 2014; Huang et al., 2007).

In addition, according to Spitzer et al., TLRs could interact and modulate with each other. TLR1 and TLR4 can form heterodimer complexes. Their extracellular segments can bind to TLR4 and block the connection between TLR4 and ligand, thus blocking the signal transduction of TLR4 (Spitzer et al., 2002). Furthermore, Bulut et al. (2001) suggested that the synergistic effect of TLR2 and TLR6 may be involved in the identification of all TLR2 ligands. Further experiments also confirmed that the fused TLR2 and TLR6 could inhibit the activation of the ligands of TLR2 and TLR4 (Spitzer et al., 2002).

One of the possible mechanisms driving TLRs dysfunction in RA is genetic variants in genes encoding these receptors. Recently, increasing number of studies has been carried out on the TLRs gene polymorphisms and the susceptibility of RA. Most of studies have focused on the genetic association between TLR2 and TLR4 genes polymorphisms and RA susceptibility. Two well-known missense mutations “Asp299Gly (rs4986790)” and “Thr399Ile (rs4986791)” in TLR4 gene have been shown to be correlated with RA risk. However, such associations were not shown in all the investigated populations (Kilding et al., 2003; Radstake et al., 2004; Zheng et al., 2010). With regard to TLR2 Arg753Gln (rs5743708), it has been shown not to be the risk factor for arthritis in a Spanish population (Sanchez et al., 2004). As for TLR1 and TLR6, no correlation of TLR1 Arg80Thr (rs5743610), Ser602Ile (rs5743618), and TLR6 Ser249Pro (rs5743810) polymorphisms in RA was observed (Jaen et al., 2009).

However, evaluation of the associations between the TLRs, especially the TLR1, TLR2, and TLR6 gene polymorphisms and RA susceptibility in Chinese Han population has been very limited. Thus, by utilizing a case-control method, we aim to investigate whether polymorphisms of the TLR-1, -2, -4, and -6 gene polymorphisms contribute to the development of RA in a Chinese Han population.

Materials and Methods

Study subjects

The experimental protocol was evaluated and approved by the Ethics Committee of The First Affiliated Hospital of Soochow University (China) (EC/19021, December 10, 2019). Written informed consent for genetic analysis was obtained from all individuals. Three hundred sixty patients who fulfill the American College of Rheumatology 1987 criteria for RA were enrolled as case group in the present study. A control group consisted of 560 healthy individuals, who carried out physical examination from the First Affiliated Hospital of Soochow University, were also included. The patients and controls were Chinese Han origin and matched for age and sex. Detailed information of patients and controls was concluded in Table 1.

Table 1.

Clinical Characteristics of Rheumatoid Arthritis Patients and Healthy Controls

Clinical characteristics	Case (mean ± SD)	Control (mean ± SD)	p
Sex ratio (female/male)	3.61 (282/78)	3.48 (435/125)	0.17
Age (years)	43.1 ± 10.4	39.8 ± 12.6	0.43
Median of evolution (months)	102 ± 73.53	—
Early onset before 40 years, n (%)	189 (52.4%)	—
Bone erosions, n (%)	129 (35.7%)	—
Shared epitope, n (%)	131 (36.5%)	—
Active RA (DAS28 ≥ 5.1), n (%)	221 (61.4%)
ESR (mm/h)	31.5 ± 12.1	4.6 ± 1.8	<0.001
CRP (mg/L)	27.3 ± 11.6	4.7 ± 1.4	<0.001
IgA IU/mL	79.3 ± 20.5	75.1 ± 14.4	0.79
IgG IU/mL	114.2 ± 17.9	6.3 ± 3.0	<0.001
IgM IU/mL	157.9 ± 22.4	7.7 ± 4.8	<0.001
RF⁺, %	266 (77.4%)	0 (0%)	<0.001
CCP⁺, %	254 (70.5%)	0 (0%)	<0.001

Disease activity score 28 (DAS28): a score for evaluation of RA activity by assessing the state of 28 joints; anti-CCP: anticyclic citrullinated peptide.

CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; RA, rheumatoid arthritis; RF, rheumatoid factor; SD, standard deviation;.

Genotyping

Genomic DNA was extracted by standard phenol chloroform method. Genotyping detection was performed on six polymorphisms of TLR-1 (rs5743610, rs5743618), TLR-2 (rs5743708), TLR-4 (rs4986790, rs4986791), and TLR-6 (rs5743810) genes by direct sequencing.

Statistical analysis

The SPSS 20.0 were applied for statistical analysis of the data. The Hardy-Weinberg equilibrium (HWE) of the single nucleotide polymorphisms (SNPs) in control group was tested with χ². The chi-squared test was used for the difference of genotype and allele frequency between control and RA groups. The corresponding odds ratios (ORs) and 95% confidence intervals (CIs) of RA risk of individuals with genetic models, including allelic, dominant, and recessive models of selected SNPs, were calculated using logistic regression analysis.

In addition, the genetic association between the alleles of selected SNPs and autoantibody status (rheumatoid factor [RF] and anticyclic citrullinated peptide [anti-CCP]) were also performed. Multiple comparison correction was performed to adjust p values using Benja Mini-Hochberg (BH) method based on False Discovery Rate (FDR) standard. Statistical significance was set at p < 0.05. Calculation power was obtained at the 0.05 level of significance, assuming an OR of 1.5 (small effect size) by using the G*Power software (www.gpower.hhu.de).

Results

A total of 360 patients with RA and 560 healthy controls were included in the present study. The genotype distribution was in HWE in the control group for all the SNPs (p > 0.05) (Table 2). Moreover, our study obtained >74.5% power at the 5% significant level (two-tailed) (Table 2).

Table 2.

Distribution of the Genotypes of TLR1,2,4,6 Gene Polymorphisms in Rheumatoid Arthritis Cases and Controls

Genes	SNPs	Case	Control	OR [95% CI], p^a_{(Allelic model)}	p ^b _(adj)	OR [95% CI], p^a _{(Dominant model)}	p ^b _(adj)	OR [95% CI], p^a _{(Recessive model)}	p ^b _(adj)	HWE in controls	Power
TLR1	Arg80Thr (rs5743610)	178/136/46	270/234/47	1.08 [0.88-1.32], 0.47	0.71	0.95 [0.73-1.24], 0.72	0.82	1.60 [1.04-2.46], 0.06	0.12	>0.05	74.5
TLR1	Ser602Ile (rs5743618)	207/126/27	425/123/12	2.21 [1.73-2.81], <0.0001	<0.0001	2.33 [1.75-3.09], <0.0001	<0.0001	3.70 [1.85-7.41], 0.0002	0.0012	>0.05
TLR2	Arg753Gln (rs5743708)	256/96/8	433/122/5	1.38 [1.05-1.81], 0.02	0.06	1.39 [1.02-1.87], 0.03	0.09	2.52 [0.82-7.77], 0.11	0.165	>0.05
TLR4	Asp299Gly (rs4986790)	360/0/0	560/0/0	—	—	—	—	—	—	>0.05
TLR4	Thr399Ile (rs4986791)	360/0/0	560/0/0	—	—	—	—	—	—	>0.05
TLR6	Ser249Pro (rs5743810)	222/116/22	363/181/16	1.22 [0.97-1.53], 0.10	0.20	1.15 [0.87-1.51], 0.33	0.66	2.21 [1.15-4.27], 0.02	0.06	>0.05

p Value were calculated using Fisher's exact test.

The FDR adjusting was carried out to adjust the p value.

“—”: not significant; p_adj, p_adjusted.

95% CI, 95% confidence interval; FDR, False Discovery Rate; HWE, Hardy-Weinberg equilibrium; OR, odds ratio; SNP, single nucleotide polymorphism; TLR, toll-like receptor.

The associations between TLRs genes polymorphisms and RA risk

Significant associations were detected between the recessive model of the TLR1 rs5743610 (OR [95% CI] = 1.60 [1.04-2.46], p = 0.03), TLR6 rs5743810 (OR [95% CI] = 2.21 [1.15-4.27], p = 0.02), and RA risk. However, the significant associations disappeared after the FDR correction (rs5743610: p_adj = 0.12; rs5743810: p_adj = 0.06) (Table 2).

Significant difference was found between the distributions of the allelic and dominant models of the TLR2 rs5743708 (allelic model: OR [95% CI] = 1.38 [1.05-1.81], p = 0.02; dominant model: OR [95% CI] = 1.39 [1.02-1.87], p = 0.03) in RA and control groups. However, these significant associations did not exist after the FDR correction (p > 0.05) (Table 2).

In addition, the frequencies of the 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), and recessive models (OR [95% CI] = 3.70 [1.85-7.41], p = 0.0002) of TLR1 rs5743618 were significantly different in RA group from that in the control group, even after the FDR correction (p < 0.05).

Furthermore, no TLR4 rs4986790 and rs4986791 mutations were detected in both RA patients and control subjects (Table 2).

The associations between risk allele in TLRs genes polymorphisms and clinical characteristics

Correlation between the TLR-1, -2, -4, and -6 risk alleles and the status of RF and anti-CCP in patients with RA was evaluated by regression analysis.

As shown in Table 3, 360 patients with RF and anti-CCP information available were divided into two groups (RF status: RF-positive [RF⁺] RA group and RF-negative [RF⁻] RA group; anti-CCP status: anti-CCP-positive [anti-CCP⁺] RA group and anti-CCP-negative [anti-CCP⁻] RA group). Results revealed that no significant association was detected between TLR1 rs5743610, rs5743618, TLR2 rs5743708, TLR4 rs4986790, rs4986791, and RF status, as well as anti-CCP status (p > 0.05). Moreover, the distribution of the TLR6 rs5743810 in RF⁺ (OR [95% CI] = 2.29 [1.42-3.69], p = 0.0007) and anti-CCP⁺ (OR [95% CI] = 2.33 [1.39-3.89], p = 0.001) RA groups were significantly different from those in RF⁻ and anti-CCP⁻ RA groups. These significant associations existed even after the FDR correction (p < 0.05) (Table 3).

Table 3.

TLR1,2,4,6 Gene Alleles Frequencies and Autoantibody Levels in Patients with Rheumatoid Arthritis

Genes	SNPs	RF⁺(freq.)	RF⁻ (freq.)	p^a, OR [95% CI]	p _adj	Anti-CC P ⁺ (freq.)	Anti-CC P ⁻ (freq.)	p^a, OR [95% CI]	p _adj
TLR1	Arg80Thr (rs5743610)	0.11	0.13	0.83 [0.48-1.44], 0.50	0.75	0.25	0.21	1.36 [0.86-2.14], 0.19	0.57
TLR1	Ser602Ile (rs5743618)	0.33	0.29	1.39 [0.86-2.25], 0.18	0.54	0.34	0.32	1.19 [0.74-1.92], 0.47	0.94
TLR2	Arg753Gln (rs5743708)	0.33	0.29	1.39 [0.86-2.25], 0.18	0.54	0.34	0.32	1.19 [0.74-1.92], 0.47	0.94
TLR4	Asp299Gly (rs4986790)	0.00	0.00	—	—	—	—	—	—
TLR4	Thr399Ile (rs4986791)	0.00	0.00	—	—	—	—	—	—
TLR6	Ser249Pro (rs5743810)	0.32	0.22	2.29 [1.42-3.69], 0.0007	0.0042	0.41	0.33	2.33 [1.39-3.89], 0.001	0.006

p Value were calculated using Fisher's exact test.

—, not calculated; .

Discussion

TLRs play an important role in both innate and adaptive immune responses (Majewska and Szczepanik, 2006). In innate immunity, TLRs directly trigger the intracellular bactericidal mechanism or induce the production of immune inflammatory factors based on the recognition of pathogenic microorganisms to expand the nonspecific defense (Cho et al., 2017). In adaptive immune response, TLRs can induce dendritic cells to mature, activate them to secrete cytokines and chemokines, and induce their expression of costimulatory molecules (Sun et al., 2018). In addition, TLRs could activate naive B cells, affect the intensity and quality of the memory T cell response, and initiate the CD8⁺T cell response against soluble protein antigen (Massonnet et al., 2009).

Thus, TLRs are widely involved in various pathways of specific immune response and in the occurrence and development of chronic immune inflammatory diseases. Furthermore, increased expression of TLRs was found in peripheral blood mononuclear cells, synovial tissues, synovial fluid, synovial macrophages, and synovial fibroblasts in RA patients. TLR-2, -3, -4, -5, -7, -8, and -9 were also demonstrated to involve in the development of RA (Ospelt et al., 2008; Sacre et al., 2016).

TLR2 and TLR4 are the most studied molecules in the TLR family. The TLR2 gene is located in the 4q31.3 region and works in concert with at least two other heterodimers such as TLR1 and TLR6. Previous studies have found that the positive rate and average fluorescence intensity of TLR2 in peripheral blood mononuclear cells in patients with RA were significantly higher than those in healthy controls suggesting that TLR2 plays an important role in the occurrence and development of RA (Yang et al., 2011).

However, little is known about the relationship of TLR2 rs5743708 and the susceptibility of RA. TLR2 rs5743708 is located at amino acid position 753 of intron. The A/G mutation causes arginine to become glutamine, which is a nonsynonymous mutation. In the present study, we found no association between the TLR2 rs5743708 and RA risk, as well as the RF and anti-CCP status, which was similar with the results reported by Sanchez et al. (2004) in a Spanish population.

The TLR4 gene is located in the 4q33.1 region. Studies on TLR4 gene polymorphisms and RA are currently focused on two missense mutation sites “Asp299Gly” and “Thr399Ile.” The Asp299Gly (TLR4/896) polymorphism is an amino acid variation, in which aspartic acid at 299 of TLR4 protein is replaced by glycine (Asp/Gly) due to missense mutation of “A/G” at 896th position of TLR4 gene. The Thr399Ile (TLR4/1196) refers to the substitution of cytosine (C) at position 1196 for thymine (T), resulting in substitution of threonine at position 399 by isoleucine (Thr/Ile). Lines of studies have reported the association between TLR4 rs4986790 and rs4986791 and RA in multiple populations. However, the results were inconsistent in different ethnicity groups. Radstake et al. found that TLR4 rs4986790 was associated with RA susceptibility, but not with RA disease activity and prognosis in a Dutch population.

However, no association was found between the TLR4 rs4986790 and rs4986791 and RA in other Caucasian populations, including French (Jaen et al., 2009), Finn (Kuuliala et al., 2006), Spanish (Sanchez et al., 2004), and British (Kilding et al., 2003). The results of the relationship of TLR4 rs4986790 and rs4986791 and RA in Asian populations were more complex. In the present study, both the TLR4 rs4986790 and rs4986791 were found to be not polymorphismic, which was similar with the previous results reported by Zheng et al. (2010), Yuan et al. (2010), and Kang and Lee (2007).

In addition, no significant association between the TLR4 rs4986790 and rs4986791 polymorphisms and RA risk was identified by meta-analysis (Lee and Song, 2013; Tizaoui et al., 2015). Thus, we may conclude that the TLR2 rs5743708, TLR4 rs4986790, and rs4986791 did not contribute to the pathogenesis of RA. These results need to be confirmed in larger number of case-control studies.

TLR1 and TLR6 are the receptors of TLR2, which could induce different transduction pathways (Elass et al., 2005; Massari et al., 2006). TLR6, TLR1 and TLR10 gene are clustered in a 54-kb region on chromosome 4p14 and encode proteins that share a high degree of homology in their overall amino acid sequences (Mikacenic et al., 2013). Genetic variations within TLR6-TLR1-TLR10 gene cluster have been reported to be associated with sarcoidosis (Veltkamp et al., 2011), prostate cancer (Stevens et al., 2010), Meniere's disease (Requena et al., 2013), Legionnaires' disease (Misch et al., 2013), and Crohn's disease (Morgan et al., 2012).

Eleven TLR1 polymorphisms have been reported in a population-based study in Sweden, and three were found to have an association with increased risk of prostate cancer (Chen et al., 2007). A 5′-UTR SNP of TLR1 gene, rs5743565, was demonstrated to have a protective effect against Graves' disease (Xiao et al., 2014). For other two TLR1 polymorphisms, rs5743610 and rs5743618, the TLR1 rs5743618 is a common nonsynonymous SNP lying just at the junction of the transmembrane and cytoplasmic domain of TLR1, resulting in a reduced response to heterodimer antagonists. In addition, the TLR1 rs5743610 and rs5743618 were reported to be associated with complicated skin and skin structure infections (cSSSIs) (Stappers et al., 2014) and Crohn's disease (Marie et al., 2006).

However, rare study has been conducted on the genetic associations between the TLR1 gene polymorphisms and RA risk. To our knowledge, this is the first study of the genetic association between the allelic, dominant, and recessive models of TLR1 rs5743610 and rs5743618 and RA susceptibility was conducted and demonstrated that the TLR1 rs5743618 was a susceptible factor for RA. Further studies with larger number of subjects are needed to investigate the genetic association between TLR1 rs5743618 and RA risk for the relatively small sample size in the present study.

Several TLR6 SNPs have been reported to be related with multiple diseases, including tuberculosis (Zhang et al., 2013), mild malaria (Leoratti et al., 2008), cSSSIs (Stappers et al., 2014), asthma (Hoffjan et al., 2005), and invasive aspergillosis (Kesh et al., 2005). The TLR6 rs5743810 T allele was found to reduce nuclear factor kappa B signaling which led to an altered level of IL-6 production (Shey et al., 2010). However, no study was conducted on the genetic association between TLR6 polymorphisms and RA. Notable, significant associations were first observed between the TLR6 rs5743810 and RA status, as well as anti-CCP status, which was different from the results reported by Jaen et al. (2009). The inconsistency may be due to the different genetic background between the two populations. The function of this SNP is still hardly known. We hypothesized that TLR6 rs5743810 might be associated with disease severity by increasing autoantibody production. To confirm this result, functional study is necessary in the future.

In summary, our results suggested that the allelic, dominant, and recessive models of TLR1 rs5743618 might be associated with the pathogenesis of RA. The TLR6 rs5743810 might be associated with clinical characteristics (RF and anti-CCP antibody) in RA in Chinese Han population. Further studies of the TLR1 rs5743618 and TLR6 rs5743810 in ethnically well-defined populations as well as functional studies of this variation are warranted to evaluate their role in the pathogenesis of RA.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

Funding Information

This study was funded by the Foundation of Changshu department of Science and Technology (2017BY28020).

References

Alarcón-Segovia

, Alarcón-Riquelme

, Cardiel

, et al. (2005) Familial aggregation of systemic lupus erythematosus, rheumatoid arthritis, and other autoimmune diseases in 1,177 lupus patients from the GLADEL cohort. Arthritis Rheumatol, 52:1138-1147.

Bulut

, Faure

, Thomas

, et al. (2001) Cooperation of toll-like receptor 2 and 6 for cellular activation by soluble tuberculosis factor and Borrelia burgdorferi outer surface protein a lipoprotein: role of toll-interacting protein and IL-1 receptor signaling molecules in toll-like receptor 2 signaling. J Immunol, 167:987-994.

Chen

, Giovannucci

, Kraft

, et al. (2007) Association between Toll-like receptor gene cluster (TLR6, TLR1, and TLR10) and prostate cancer. Cancer Epidemiol Biomark Prev, 16:1982.

Cho

, Wencheng

, Takeshita

, et al. (2017) Evidence for the presence of cell-surface-bound and intracellular bactericidal toxins in the dinoflagellate, Heterocapsa circularisquama. Aquat Toxicol, 189:209-215.

Elass

, Laëtitia

Aubry

, Masson

, et al. (2005) Mycobacterial lipomannan induces matrix metalloproteinase-9 expression in human macrophagic cells through a toll-like receptor 1 (TLR1)/TLR2- and CD14-dependent mechanism. Infect Immunity, 73:7064-7068.

Gallacher

(2015) Rheumatoid arthritis. Nursing standard: official newspaper of the Royal Coll Nurs, 30:61-62.

Hoffjan

, Stemmler

, Parwez

, et al. (2005) Evaluation of the toll-like receptor 6 Ser249Pro polymorphism in patients with asthma, atopic dermatitis and chronic obstructive pulmonary disease. BMC Med Genet, 6:34.

Huang

, Ma

, Adebayo

, et al. (2007) Increased macrophage activation mediated through Toll-like receptors in rheumatoid arthritis. Arthrit Rheumatol, 56:2192-2201.

Iwahashi

, Yamamura

, Aita

, et al. (2004) Expression of toll-like receptor 2 on CD16⁺ blood monocytes and synovial tissue macrophages in rheumatoid arthritis. Arthrit Rheumatol, 50:1457-1467.

10.

Jaen

, Petit-Teixeira

, Kirsten

, et al. (2009) No evidence of major effects in several Toll-like receptor gene polymorphisms in rheumatoid arthritis. Arthrit Res Ther, 11:R5.

11.

Kang

, Lee

(2007) Genotypic analysis of Asp299Gly and Thr399Ile polymorphism of Toll-like receptor. Rheumatol Int, 27:887-889.

12.

Karlson

, Ding

, Keenan

, et al. (2013) Association of environmental and genetic factors and gene-environment interactions with risk of developing rheumatoid arthritis. Arthrit Care Res, 65:1147-1156.

13.

Kesh

, Mensah

, Peterlongo

, et al. (2005) TLR1 and TLR6 polymorphisms are associated with susceptibility to invasive aspergillosis after allogeneic stem cell transplantation. Ann N Y Acad Sci, 1062:95-103.

14.

Kilding

, Akil

, Till

, et al. (2003) A biologically important single nucleotide polymorphism within the toll-like receptor-4 gene is not associated with rheumatoid arthritis. Clin Exp Rheumatol, 21:340-342.

15.

Kuo

, Grainge

, Valdes

, et al. (2017) Familial aggregation of rheumatoid arthritis and co-aggregation of autoimmune diseases in affected families: a nationwide population-based study. Rheumatology, 56:928-933.

16.

Kuuliala

, Orpana

, Leirisalo-Repo

, et al. (2006) Polymorphism at position +896 of the toll-like receptor 4 gene interferes with rapid response to treatment in rheumatoid arthritis. Ann Rheum Dis, 65:1241-1243.

17.

Lee

, Song

(2013) Meta-analysis demonstrates association between TLR polymorphisms and rheumatoid arthritis. Genet Mol Res, 12:328-334.

18.

Leoratti

, Farias

, Alves

, et al. (2008) Variants in the Toll-like receptor signaling pathway and clinical outcomes of malaria. J Infect Dis, 198:772-780.

19.

Majewska

, Szczepanik

(2006) The role of Toll-like receptors (TLR) in innate and adaptive immune responses and their function in immune response regulation. Postep Hig Med Dosw, 60:52-63.

20.

Marie

, Sofie

, Kristel

(2006) Toll-like receptor-1, -2, and -6 polymorphisms influence disease extension in inflammatory bowel diseases. Inflamm Bowel Dis, 12:1-8.

21.

Massari

, Visintin

, Gunawardana

, et al. (2006) Meningococcal porin PorB binds to TLR2 and requires TLR1 for signaling. J Immunol, 176:2373-2380.

22.

Massonnet

, Delwail

, Ayrault

, et al. (2009) Increased immunoglobulin A in alcoholic liver cirrhosis: exploring the response of B cells to Toll-like receptor 9 activation. Clin Exp Immunol, 158:115-124.

23.

Mikacenic

, Reiner

, Holden

, et al. (2013) Variation in the TLR10/TLR1/TLR6 locus is the major genetic determinant of inter-individual difference in TLR1/2-mediated responses. Genes Immun, 14:52-57.

24.

Misch

. Verbon

, Prins

, et al. (2013) A TLR6 polymorphism is associated with increased risk of Legionnaires' disease. Genes Immun, 14:420-426.

25.

Morgan

, Lam

, Han

, et al. (2012) Genetic variation within TLR10 is associated with Crohn's disease in a New Zealand population. Hum Immunol, 73:416-420.

26.

Netea

, Meer

JWMVD

, Kullberg

(2006) Recognition of pathogenic microorganisms by Toll-like receptors. Drugs Today (Barcelona, Spain: 1998) 42 Suppl, A:99-105.

27.

Ospelt

, Brentano

, Rengel

, et al. (2008) Overexpression of toll-like receptors 3 and 4 in synovial tissue from patients with early rheumatoid arthritis: toll-like receptor expression in early and longstanding arthritis. Arthritis Rheum, 58:3684-3692.

28.

Ospelt

, Gay

(2010) TLRs and chronic inflammation. Int J Biochem Cell Biol, 42:500-505.

29.

Radstake

, Franke

, Hanssen

, et al. (2004) The Toll-like receptor 4 Asp299Gly functional variant is associated with decreased rheumatoid arthritis disease susceptibility but does not influence disease severity and/or outcome. Arthritis Rheum, 50:999-1001.

30.

Requena

, Gazquez

, Moreno

, et al. (2013) Allelic variants in TLR10 gene may influence bilateral affectation and clinical course of Meniere’ s disease. Immunogenetic, 65:345-355.

31.

Ruckdeschel

, Pfaffinger

, Haase

, et al. (2004) Signaling of apoptosis through TLRs critically involves Toll/IL-1 receptor domain-containing adapter inducing IFN-a, but not MyD88, in bacteria-infected murine macrophages. J Immunol, 173:3320-3328.

32.

Sacre

, Lo

, Gregory

, et al. (2016) Oligodeoxynucleotide inhibition of Toll-like receptors 3, 7, 8, and 9 suppresses cytokine production in a human rheumatoid arthritis model. Eur J Immunol, 46:772-781.

33.

Sanchez

, Orozco

, Lopez-Nevot

, et al. (2004) Polymorphisms of toll-like receptor 2 and 4 genes in rheumatoid arthritis and systemic lupus erythematosus. Tissue Antigens, 63:54-57.

34.

Shey

, Randhawa

, Bowmaker

, et al. (2010) Single nucleotide polymorphisms in toll-like receptor 6 are associated with altered lipopeptide- and mycobacteria-induced interleukin-6 secretion. Genes Immun, 11:561-572.

35.

Spitzer

, Visintin

, Mazzoni

, et al. (2002) Toll-like receptor 1 inhibits Toll-like receptor 4 signaling in endothelial cells. Eur J Immunol, 32:1182-1187.

36.

Stappers

MHT

, Thys

, Oosting

, et al. (2014) TLR1, TLR2, and TLR6 gene polymorphisms are associated with increased susceptibility to complicated skin and skin structure infections. J Infect Dis, 210:311.

37.

Stevens

, Hsing

, Talbot

, et al. (2010) Genetic variation in the toll-like receptor gene cluster (TLR10-TLR1-TLR6) and prostate cancer risk. Int J Cancer, 123:2644-2650.

38.

Sun

, Dai

, Wu

, et al. (2018) TSLP-activated dendritic cells induce T helper type 2 inflammation in Aspergillus fumigatus keratitis. Exp Eye Res, 171:120-130.

39.

Thwaites

, Chamberlain

, Sacre

(2014) Emerging role of endosomal toll-like receptors in rheumatoid arthritis. Front Immunol, 5:1.

40.

Tizaoui

, Naouali

, Kaabachi

, et al. (2015) Association of Toll like receptor Asp299Gly with rheumatoid arthritis risk: a systematic review of case-control studies and meta-analysis. Pathol Res Pract, 211:219-225.

41.

Veltkamp

, Moorsel

, Rijkers

, et al. (2011) Genetic variation in the Toll-like receptor gene cluster (TLR10-TLR1-TLR6) influences disease course in sarcoidosis. Tissue Antigens, 79:25-32.

42.

Xiao

, Liu

, Lin

, et al. (2014) Polymorphisms in TLR1, TLR6 and TLR10 genes and the risk of Graves' disease. Autoimmunity, 48:1-6.

43.

Yang

, Mi

, Wang

, et al. (2011) Expression and significance of TLR2 in rheumatoid arthritis. China Modern Doctor, 49:19-20.

44.

, Li

, Duan

, et al. (2018) Chinese registry of rheumatoid arthritis (CREDIT): introduction and prevalence of remission in Chinese patients with rheumatoid arthritis. Clin Exp Rheumatol, 36:836-840.

45.

Yuan

, Xia

, Ma

, et al. (2010) Lack of the toll-like receptor 4 gene polymorphisms Asp299Gly and Thr399ile in a Chinese population. Int J Neurosci, 120:415-420.

46.

Zhang

, Jiang

, Yang

, et al. (2013) Toll-like receptor -1, -2, and -6 polymorphisms and pulmonary tuberculosis susceptibility: a systematic review and meta-analysis. PLoS One, 8:e63357.

47.

Zheng

, Li

, Wei

, et al. (2010) Lack of association of TLR4 gene Asp299Gly and Thr399Ile polymorphisms with rheumatoid arthritis in Chinese Han population of Yunnan Province. Rheumatol Int, 30:1249-1252.