Genetic variations of Toll-like receptor 9 predispose to systemic lupus erythematosus in Japanese population

Single nucleotide polymorphisms of pattern recognition receptors and chronic periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis is a multifactorial disease influenced partly by genetics. Activation of pattern recognition receptors (PRRs) can lead to the up-regulation of inflammatory pathways, resulting in periodontal tissue destruction. Hence, functional polymorphisms located in PRRs can explain differences in host susceptibility to periodontitis. This study investigated single nucleotide polymorphisms of PRRs including toll-like receptor (TLR)2 (G2408A), TLR4 (A896G), TLR9 (T1486C), TLR9 (T1237C) and CD14 (C260T) in patients with chronic periodontitis and in periodontally healthy subjects.

METHODS

One-hundred and fourteen patients with chronic periodontitis and 77 periodontally healthy subjects were genotyped using TaqMan® allelic discrimination assays. Fisher's exact test and chi-square analyses were performed to compare genotype and allele frequencies.

RESULTS

The frequency of subjects with the CC genotype of CD14 (C260T) (24.6% in the chronic periodontitis group vs. 13% in the periodontally healthy group) and those expressing the T allele of CD14 (C260T) (CT and TT) (75.4% in the chronic periodontitis group vs. 87% in the periodontally healthy group) was statistically different among groups (p = 0.04). Homozygocity for the C allele of the CD14 (C260T) polymorphism (CC) was associated with a two--fold increased susceptibility to periodontitis (p = 0.04; odds ratio, 2.49; 95% confidence interval, 1.06-6.26). Individuals with the CC genotype of TLR9 (T1486C) (14.9% in the chronic periodontitis group vs. 28.6% in the periodontally healthy group) and those expressing the T allele of TLR9 (T1486C) (CT and TT) (85.1% in the chronic periodontitis group vs. 71.4% in the periodontally healthy group) were also significantly differently distributed between groups without adjustment (p = 0.03). Further analysis of nonsmokers revealed a significant difference in the distribution of genotypes between groups for TLR9 (T1486C; p = 0.017) and CD14 (C260T; p = 0.03), polymorphisms again without adjustment.

CONCLUSION

The CC genotype of CD14 (C260T) is related to susceptibility to chronic periodontitis in Caucasians. In addition, differences observed in the distribution of TLR9 (T1486C) genotypes between groups warrant further investigation.

Toll-like receptor gene polymorphisms are associated with susceptibility to Graves' ophthalmopathy in Taiwan males

BACKGROUND

Toll-like receptors (TLRs) are a family of pattern-recognition receptors, which plays a role in eliciting innate/adaptive immune responses and developing chronic inflammation. The polymorphisms of TLRs have been associated with the risk of various autoimmune diseases, including systemic lupus erythematosus (SLE), multiple sclerosis and rheumatorid arthritis. The aim of this study was to evaluate whether TLR genes could be used as genetic markers for the development of Graves' ophthalmopathy (GO).

METHODS

6 TLR-4 and 2 TLR-9 gene polymorphisms in 471 GD patients (200 patients with GO and 271 patients without GO) from a Taiwan Chinese population were evaluated.

RESULTS

No statistically significant difference was observed in the genotypic and allelic frequencies of TLR-4 and TLR-9 gene polymorphisms between the GD patients with and without GO. However, sex-stratified analyses showed that the association between TLR-9 gene polymorphism and GO phenotype was more pronounced in the male patients. The odds ratios (ORs) was 2.11 (95% confidence interval [CI] = 1.14-3.91) for rs187084 AàG polymorphism and 1.97 (95% CI = 1.07-3.62) for rs352140 AàG polymorphism among the male patients. Increasing one G allele of rs287084 and one A allele of rs352140 increased the risk of GO (p values for trend tests were 0.0195 and 0.0345, respectively). Further, in haplotype analyses, the male patients carrying the GA haplotype had a higher risk of GO (odds ratio [OR] = 2.02, 95% confidence interval [CI] = 1.09-3.73) than those not carrying the GA haplotype.

CONCLUSION

The present data suggest that TLR-9 gene polymorphisms were significantly associated with increased susceptibility of ophthalmopathy in male GD patients.

Role for toll-like receptors in autoimmune disease: the example of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem disease characterized by an autoimmune response to nuclear antigens. Although the pathophysiology of SLE remains incompletely understood, many recent studies indicate a major role for innate immunity. The toll-like receptors (TLRs), which play a key role in innate responses to infections, are also involved in acute and chronic inflammatory processes induced by endogenous ligands. Numerous in vitro studies have established that TLR7 and TLR9 are involved in immune complex recognition. Activation of these receptors leads to activation of immune cells, most notably B cells and dendritic cells, and to the inappropriate production of many cytokines known to be directly involved in the pathogenesis of SLE. These data prompted studies in several murine models of SLE to assess the impact of inactivation or overexpression of genes encoding TLRs or molecules involved in TLR signaling pathways. The results confirmed the major role for TLR7 and suggested involvement of TLR4 in the induction of an aggressive autoimmune response. However, in vivo data suggest a protective effect of TLR9, thus contradicting the in vitro results. In humans, genetic studies have identified polymorphisms associated with increased susceptibility to SLE.

A naturally occurring variant in human TLR9, P99L, is associated with loss of CpG oligonucleotide responsiveness

The innate immune system employs Toll-like receptors (TLRs) for the detection of invading microorganisms based on distinct molecular patterns. For example, TLR9 is activated by microbial DNA and also by short therapeutic CpG-containing oligonucleotides (CpG-ODN). TLR9 activation leads to the production of interferons and the priming of humoral adaptive immune responses. Unfortunately, the principles of ligand recognition by TLR9 are poorly understood, and genetic variants of TLR9, which may affect its function, have not been characterized systematically on the molecular level. We therefore sought to functionally characterize reported single nucleotide polymorphisms of TLR9 in the HEK293 model system. We discovered that two variants, P99L and M400I, are associated with altered receptor function regarding NF-κB activation and cytokine induction. Our investigations show that for the most functionally impaired variant, P99L, the ability to respond to physiological and therapeutic TLR9 ligands is severely compromised. However, CpG-ODN binding is normal. CpG-ODN recognition by TLR9 thus appears to involve two separate events, CpG-ODN binding and sensing. Our studies highlight Pro-99 as a residue important for the latter process. In genotyping studies, we confirmed that both M400I (rs41308230) and P99L (rs5743844) are relatively rare variants of TLR9. Our data add rs41308230 and rs5743844 to the list of functionally important TLR variants and warrant further research into their relevance for infectious disease susceptibility or responsiveness to CpG-ODN-based therapies.

Toll-like receptor 9 polymorphisms influence mother-to-child transmission of human immunodeficiency virus type 1

Background

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and play a crucial role in the host's innate immune response. Genetic variations in TLR genes may influence host-viral interactions and might impact upon the risk of mother-to-child transmission (MTCT) of Human Immunodeficiency Virus type 1 (HIV-1). The aim of this study was to investigate the influence of genetic variants of TLR 9 gene on MTCT.

Methods

Three hundred children (118 HIV-1-infected and 182 HIV-1-uninfected) born to HIV-1-infected mothers were studied. Single nucleotide polymorphisms (SNPs) NM_017442.2: c.4-44G > A (rs352139) and c.1635A > G (rs352140) of the TLR9 gene were genotyped by TaqMan allelic discrimination assay. Statistical analyses were performed using SNPStats program.

Results

When considered separately, neither of the two SNPs was significantly associated with risk of HIV-1 infection. However, the [A;A] and [G;G] haplotypes were associated with a higher risk of HIV-1 infection compared to the prevalent [G;A] haplotype [odds ratio (OR) = 3.16, 95% confidence interval (CI) 1.24-8.03, p = 0.016, and OR = 5.54, 95% CI 1.76-17.50, p = 0.004, respectively].

Conclusions

Overall, results demonstrate a significant correlation between specific genetic variants of the TLR9 gene and risk of MTCT of HIV-1, thus confirming a critical role of innate immunity in perinatal HIV-1 infection. Strategies aimed at modulating innate immunity might be useful for future treatment of pediatric HIV-1 infection and AIDS.

Genetic associations in type I interferon related pathways with autoimmunity

Type I interferons play an outstanding role in innate and adaptive immunity by enhancing functions of dendritic cells, inducing differentiation of monocytes, promoting immunoglobulin class switching in B cells and stimulating effector functions of T cells. The increased production of IFNα/β by plasmacytoid dendritic cells could be responsible for not only efficient antiviral defence, but it also may be a pathological factor in the development of various autoimmune disorders. The first evidence of a genetic link between type I interferons and autoimmune diseases was the observation that elevated IFNα activity is frequently detected in the sera of patients with systemic lupus erythematosus, and that this trait shows high heritability and familial aggregation in their first-degree healthy relatives. To date, a number of genes involved in interferon signalling have been associated with various autoimmune diseases. Patients with systemic lupus erythematosus, Sjögren's syndrome, dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis display a specific expression pattern of interferon-dependent genes in their leukocytes, termed the interferon signature. Here, in an attempt to understand the role of type I interferons in the pathogenesis of autoimmunity, we review the recent advances in the genetics of autoimmune diseases focusing on the association of genes involved in type I interferon pathways.

The role of toll-like receptors in host defenses and their relevance to dermatologic diseases

The family of toll-like receptors (TLRs) plays a central role in the cutaneous immune defense system. To date, different TLRs have been found on several major cell populations of the skin, such as keratinocytes, fibroblasts, antigen-presenting cells, and melanocytes. Activation of TLRs leads, via different intracellular signaling pathways, to the production of pro-inflammatory stimuli, and is considered a danger signal that should transform the skin in to the functional state of defense. However, TLRs have also been implicated in tissue homeostasis and renewal. Within the group of TLRs, two types have been identified: surface-expressed TLRs, which are predominantly active against bacterial cell wall compounds; and intracellular receptors, which preferentially recognize virus-associated pattern molecules. In addition, surface-expressed receptors trigger phagocytotic and maturation signals, while the intracellular TLRs lead to the induction of antiviral genes. Our review aims to outline the importance of TLRs in the pathogenesis of numerous skin diseases and the potential of TLR agonists as a treatment option for various skin diseases.

Polymorphisms in toll-like receptor 4 and toll-like receptor 9 influence viral load in a seroincident cohort of HIV-1-infected individuals

OBJECTIVES

Toll-like receptors (TLRs) are innate immune sensors that are integral to resisting chronic and opportunistic infections. Mounting evidence implicates TLR polymorphisms in susceptibilities to various infectious diseases, including HIV-1. We investigated the impact of TLR single nucleotide polymorphisms (SNPs) on clinical outcome in a seroincident cohort of HIV-1-infected volunteers.

DESIGN

We analyzed TLR SNPs in 201 antiretroviral treatment-naive HIV-1-infected volunteers from a longitudinal seroincident cohort with regular follow-up intervals (median follow-up 4.2 years, interquartile range 4.4). Participants were stratified into two groups according to either disease progression, defined as peripheral blood CD4(+) T-cell decline over time, or peak and setpoint viral load.

METHODS

Haplotype tagging SNPs from TLR2, TLR3, TLR4, and TLR9 were detected by mass array genotyping, and CD4(+) T-cell counts and viral load measurements were determined prior to antiretroviral therapy initiation. The association of TLR haplotypes with viral load and rapid progression was assessed by multivariate regression models using age and sex as covariates.

RESULTS

Two TLR4 SNPs in strong linkage disequilibrium [1063 A/G (D299G) and 1363 C/T (T399I)] were more frequent among individuals with high peak viral load compared with low/moderate peak viral load (odds ratio 6.65, 95% confidence interval 2.19-20.46, P < 0.001; adjusted P = 0.002 for 1063 A/G). In addition, a TLR9 SNP previously associated with slow progression was found less frequently among individuals with high viral setpoint compared with low/moderate setpoint (odds ratio 0.29, 95% confidence interval 0.13-0.65, P = 0.003, adjusted P = 0.04).

CONCLUSION

This study suggests a potentially new role for TLR4 polymorphisms in HIV-1 peak viral load and confirms a role for TLR9 polymorphisms in disease progression.

Association of the toll-like receptor 2 A-16934T promoter polymorphism with severe atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a multifactorial pathogenesis and increasing incidence in the Western world. A genetically determined defective function of pattern recognition receptors such as toll-like receptors (TLRs) has been proposed as a candidate mechanism in the pathogenesis of AD.

AIM

To study the impact of genetic predisposition of five genes encoding for pattern recognition-related molecules for the phenotype of AD.

METHODS

We examined nine different single-nucleotide polymorphism (SNP) frequencies in the genes encoding TLR1, -2, -4, -9 and the adapter molecule TIRAP by PCR with subsequent melting curve analysis in a case/control cohort of 136 adult AD patients and 129 age and gender matched non-atopic, healthy individuals. TLR2-expression and -function in cells from genotyped individuals were analysed.

RESULTS

For the SNPs examined, similar genotype frequencies were found in both groups. In a subgroup of patients suffering from severe AD (SCORAD >50), a significantly increased representation of the A-allele in position -16934 of the tlr2 gene was present (P = 0.004). Constitutive tlr2 mRNA expression in peripheral monocytes was independent of this tlr2 promoter SNP. Stimulation assays indicated that IL-6, but not TNF-alpha secretion following TLR2 stimulation is reduced in homozygous tlr2-16934-A allele carriers.

CONCLUSION

These data indicate that TLR2 is relevant for the phenotype of severe AD in adults.

Toll-like receptors and NOD-like receptors in rheumatic diseases

The past 10 years have seen the description of families of receptors that drive proinflammatory cytokine production in infection and tissue injury. Two major classes have been examined in the context of inflammatory joint disease--the Toll-like receptors (TLRs) and NOD-like receptors (NLRs). TLRs such as TLR2 and TLR4 are being implicated in the pathology of rheumatoid arthritis, ankylosing spondylitis, lyme arthritis and osteoarthritis. Nalp3 has been identified as a key NLR for IL-1beta production and has been shown to have a particular role in gout. These findings present new therapeutic opportunities, possibly allowing for the replacement of biologics with small molecule inhibitors.

Pathogen recognition and inflammatory signaling in innate immune defenses

The innate immune system constitutes the first line of defense against invading microbial pathogens and relies on a large family of pattern recognition receptors (PRRs), which detect distinct evolutionarily conserved structures on pathogens, termed pathogen-associated molecular patterns (PAMPs). Among the PRRs, the Toll-like receptors have been studied most extensively. Upon PAMP engagement, PRRs trigger intracellular signaling cascades ultimately culminating in the expression of a variety of proinflammatory molecules, which together orchestrate the early host response to infection, and also is a prerequisite for the subsequent activation and shaping of adaptive immunity. In order to avoid immunopathology, this system is tightly regulated by a number of endogenous molecules that limit the magnitude and duration of the inflammatory response. Moreover, pathogenic microbes have developed sophisticated molecular strategies to subvert host defenses by interfering with molecules involved in inflammatory signaling. This review presents current knowledge on pathogen recognition through different families of PRRs and the increasingly complex signaling pathways responsible for activation of an inflammatory and antimicrobial response. Moreover, medical implications are discussed, including the role of PRRs in primary immunodeficiencies and in the pathogenesis of infectious and autoimmune diseases, as well as the possibilities for translation into clinical and therapeutic applications.

Improved outcome of hematopoietic SCT in patients with homozygous gene variant of Toll-like receptor 9

Toll-like receptor 9 (TLR9) is part of the innate immune system, which is activated by CpG oligonucleotides (ODNs) and produces potent Th1-type innate and adaptive immune responses. It is reported that TLR9 gene variants, T1486C and T1237C, are associated with a reduced TLR9 expression compared with the wild-type gene. In two cohort analyses, we evaluated the influence of these gene variants on the outcome of transplant in 413 patients and donors. A retrospective analysis of the first cohort (n=293) showed that the homozygous CC gene variant of TLR9 (1486) compared with TC/TT gene variants was significantly associated with a markedly improved 5-year TRM (11.7 versus 36.4%, P<0.003), 5-year OS (86.1 vs 48.3%, P<0.001) and a lower relapse rate (13.2 vs 33.3%, P<0.007), whereas the occurrence of acute GVHD was not different. A prospectively performed analysis of the second cohort (n=120) and multivariate analyses confirmed the influence of the CC gene variant on these end points. Compared with patients with TC/TT gene at position 1486 of TLR9, patients with the homozygous CC gene variant had a lower TLR9 mRNA expression and a delayed T-cell immune reconstitution after transplant, which might prevent them from overwhelming immune responses as sepsis or systemic inflammatory response syndrome (SIRS) associated with an increased TRM. In vitro studies using CpG-rich ODNs showed an upregulation of TLR9 expression in cell lines with CC gene variant, but not in cell lines with wild-type gene.

Association study of a single nucleotide polymorphism in the exon 2 region of toll-like receptor 9 (TLR9) gene with susceptibility to systemic lupus erythematosus among Chinese

Toll-like receptor 9 (TLR9) plays an important role in the induction and regulation of the innate immune system or adaptive immune responses. Genetic variations within human TLR9 have been reported to be associated with a range of immune-related diseases, such as asthma, systemic lupus erythematosus (SLE) and so on. Family-based association analysis was performed to further investigate whether a single nucleotide polymorphism (rs352140) in the exon 2 region of TLR9 gene is associated with susceptibility to SLE in a Chinese population. A total of 77 patients with SLE from 74 nuclear families, aged from 12 to 63 years, were enrolled according to 1997 criteria of American College of Rheumatology (ACR), 211 family members of these patients were also included. Genotyping was performed by PCR-restriction fragment length polymorphism (PCR-RFLP) assay. Among 77 patients with SLE, the CC, CT and TT genetype frequencies of the SNP (rs352140) were 20.8, 61.0 and 18.2%, respectively. Single loci analysis suggested that the T allele at position of rs352140 was significantly associated with the susceptibility to SLE (Z = 2.357, P = 0.018402) in dominant model, but not in additive or recessive model. Genetype analysis showed that individuals with CT genetype had greater susceptibility to SLE than those without (Z = 2.004, P = 0.045067). Our study suggests that a single nucleotide polymorphism (rs352140) in the exon 2 region of TLR9 gene may be a susceptibility factor for SLE in Chinese population.

The expressions of Toll-like receptor 9 and T-bet in circulating B and T cells in newly diagnosed, untreated systemic lupus erythematosus and correlations with disease activity and laboratory data in a Chinese population

Toll-like receptor 9 (TLR9) plays a controversial role in the pathogenesis of systemic lupus erythematosus (SLE). T-bet may be involved in the processes between the initiation of TLR9 activation and the antibodies' production. To clarify the paradox of TLR9, we investigated the intracellular expressions of TLR9 and T-bet in B and T cells in peripheral blood samples from 35 newly diagnosed, untreated patients with SLE and 16 healthy subjects by flow cytometry (FCM). And we collected the clinic laboratory data obtained from the same individual blood sample tested by FCM each time. And the correlations among the expression levels of the two proteins and SLE laboratory data were calculated. We found the percentages of B cells expressing TLR9 and T-bet and of T cells expressing TLR9 were significantly elevated in SLE patients when compared with healthy controls. There was a significantly negative relationship between the proportion of B cells expressing TLR9 and SLE Disease Activity Index (SLEDAI) score. The serum levels of anti-dsDNA antibody reversely correlated with the mean fluorescence intensity (MFI) of B cells co-expressing T-bet and TLR9. The serum levels of anti-C1q antibody significantly associated with the proportion of B cells expressing T-bet. Also, the serum levels of IgM and IgA antibodies both significantly correlated with TLR9 and T-bet expressions in T and B cells. According to the immunological pathway knowledge and the mutually verified associations, the following conclusions are made. Expressions of TLR9 and T-bet were increased in patients with SLE. TLR9 may have a role to play in protecting against lupus. And the increase of the co-expression of TLR9 and T-bet may be of benefit to the protective antibodies' production and pathogenic antibodies' decline, and could be regarded as a good sign for lupus demission and/or treatment.

Association of STAT4 with susceptibility to rheumatoid arthritis and systemic lupus erythematosus in the Japanese population

OBJECTIVE

STAT4 encodes a transcriptional factor that transmits signals induced by several key cytokines, and it might be a key molecule in the development of autoimmune diseases. Recently, a STAT4 haplotype was reported to be associated with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in Caucasian populations. This was replicated in a Korean RA population. Interestingly, the degree of risk of RA susceptibility with the STAT4 haplotype was similar in the Caucasian and Korean populations. The present study was undertaken to investigate the effect of STAT4 on susceptibility to RA and SLE in the Japanese.

METHODS

We performed an association study using 3 independent Japanese RA case-control populations (total 3,567 cases and 2,199 controls) and 3 independent Japanese SLE populations (total 591 cases). All samples were genotyped using the TaqMan fluorogenic 5' nuclease assay for single-nucleotide polymorphism (SNP) rs7574865, which tags the susceptibility haplotype. The association of the SNP with disease susceptibility in each case-control study was calculated using Fisher's exact test, and the results were combined, using the Mantel-Haenszel method, to obtain combined odds ratios (ORs).

RESULTS

We observed a significant association of the STAT4 polymorphism with susceptibility to both RA and SLE. The combined ORs for RA and SLE, respectively, were 1.27 (P = 8.4 x 10(-9)) and 1.61 (P = 2.1 x 10(-11)) for allele frequency distribution; these ORs were quite similar to those previously observed in the Caucasian population.

CONCLUSION

We conclude that STAT4 is associated with RA and SLE in the Japanese. Our results indicate that STAT4 is a common genetic risk factor for autoimmune diseases, with similar strength across major racial groups.

Bridging Toll-like- and B cell-receptor signaling: meet me at the autophagosome

In this issue of Immunity, Chaturvedi et al. (2008) describe a mechanism for the bridging of innate and adaptive immune receptor functions. In their model, B cell-receptor signaling induces the fusion of Toll-like receptor 9 (TLR9)-containing endosomes with internalized signaling-competent BCR into autophagosomes.

The B cell receptor governs the subcellular location of Toll-like receptor 9 leading to hyperresponses to DNA-containing antigens

Synergistic engagement of the B cell receptor (BCR) and Toll-like receptor 9 (TLR9) in response to DNA-containing antigens underlies the production of many autoantibodies in systemic autoimmune diseases. However, the molecular basis of this synergistic engagement is not known. Given that these receptors are spatially segregated, with the BCR on the cell surface and TLR9 in endocytic vesicles, achieving synergy must involve unique mechanisms. We show that upon antigen binding, the BCR initiates signaling at the plasma membrane and continues to signal to activate MAP kinases as it traffics to autophagosome-like compartments. The internalized BCR signals through a phospholipase-D-dependent pathway to recruit TLR9-containing endosomes to the autophagosome via the microtubular network. The recruitment of TLR9 to the autophagosomes was necessary for hyperactivation of MAP kinases. This unique mechanism for BCR-induced TLR9 recruitment resulting in B cells hyperresponses may provide new targets for therapeutics for autoimmune diseases.

TLR-activated B cells suppress T cell-mediated autoimmunity

TLR sense microbial infections, and control activation of immune responses. Dendritic cells, macrophages, and B lymphocytes express TLR and the TLR-signaling adaptor protein MyD88. The impact of TLR-activated B cells on T cell-mediated inflammation is unknown. In this study, we have used mice carrying B cell-restricted deficiencies in MyD88 or in distinct TLR to examine the impact of TLR-activated B cells on a T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis (EAE). We demonstrate that TLR-signaling in B cells suppresses inflammatory T cell responses (both Th1 and Th17), and stimulates recovery from EAE. Only certain TLR are required on B cells for resolution of EAE, and these are dispensable for disease initiation, indicating that a category of TLR agonists preferentially triggers a suppressive function in B cells and thereby limits autoimmune disease. The TLR agonists controlling the regulatory function of B cells are provided by components of Mycobacterium tuberculosis present in the adjuvant. Thus, MyD88 signaling in B cells antagonizes MyD88 signaling in other cells, which drives differentiation of Th17 cells and is required for induction of EAE. Altogether, our data indicate that B cells link recognition of microbial products via TLR to suppression of a T cell-mediated autoimmune disease.

Toll-like receptor polymorphisms and susceptibility to human disease

Although several lines of evidence suggest that variation in human inflammation is genetically controlled, the genes which regulate these responses are largely unknown. TLRs (Toll-like receptors) mediate recognition of microbes, regulate activation of the innate immune response and influence the formation of adaptive immunity. Cellular and molecular studies over the past several years have identified a number of common TLR polymorphisms that modify the cellular immune response and production of cytokines in vitro. In addition, human genetic studies suggest that some of these polymorphisms are associated with susceptibility to a spectrum of diseases. In this review, we summarize studies of common TLR polymorphisms and how this work is beginning to illuminate the influence of human variation on inflammation and disease susceptibility.

Association of polymorphisms in complement component C3 gene with susceptibility to systemic lupus erythematosus

OBJECTIVE

Identification of the genes responsible for systemic lupus erythematosus (SLE).

METHODS

All the exons and putative promoter regions of 53 candidate genes (TNFRSF6/Fas, TNFSF6/FasL, Fli1, TNFSF10/TRAIL, TNFSF12/TWEAK, Bcl-2, PTEN, FADD, TRADD, CDKN1A, TNFRSF1A/TNFR1, TNFRSF4/OX40, TNFSF4/OX40L, TNFSF5/CD40L, TNFSF13B/BAFF, ICOS, CTLA4, CD28, FYN, G2A, CR2, PTPRC/CD45, CD22, CD19, Lyn, PDCD1, PTPN6, TGFB1, TGFB2, TGFB3, TGFBR1, TGFBR2, TGFBR3, CD3Z, DNASE1, APCS, MERTK, C3, C1QA, C1QB, C1QG, C2, MBL2, IGHM, IL-2, IL-4, IL-10, IFNG, TNFA, MAN2A1, TNFRSF11A/RANK, TNFRSF11B/OPG, TNFSF11/OPGL) were screened for single nucleotide polymorphisms (SNPs) and their association with SLE was assessed by case-control studies. A total of 509 cases and 964 controls of Japanese descent were enrolled.

RESULTS

A total of 316 SNPs was identified. When analysed in the Japanese population, the allele frequencies of T at rs7951 and G at rs2230201 of the C3 gene were 0.110 and 0.626, respectively, in SLE patients; significantly higher than the frequencies of 0.081 and 0.584, respectively, in controls [odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.05-1.86, P = 0.016 and OR=1.19, 95% CI = 1.01-1.41, P = 0.038, respectively]. The mean serum C3 level of carriers of the rs7951 T allele was significantly lower than that of non-carriers of the T allele in 87 SLE patients whose medical records were available (P = 0.0018).

CONCLUSION

rs7951 T allele of the C3 gene was significantly associated with SLE, and decreased serum level of C3 seems to be correlated with this allele.