OBJECTIVE:
To assess the relationship between the HLA-DRB1 genes with disease severity as assessed by radiological erosions in Malaysian patients with rheumatoid arthritis (RA).
METHODS:
In this cross-sectional study, we studied 61 RA patients who fulfilled the ACR criteria for the diagnosis of RA. HLA-DRB1 genotyping was performed by sequence specific primer (SSP) - PCR. Radiological grading and erosive score of the hands and wrists was calculated according to the Larsen-Dale method. Demographic data and treatment given to the patients were obtained from their case records.
RESULTS:
Fifty-six females and five males were studied from three ethnic groups. In 57 patients with erosions, rheumatoid factor was detected in 80%, HLA-DR4 in 40%, HLA-DRB1*0405 in 24% and shared epitope (SE) in 31%. The median delay in starting DMARDs was 24 months. The presence of rheumatoid factor, HLA-DR4 and HLA-DRB1*0405 were not significantly associated with a worse erosive score. Patients who possessed the SE had a higher erosive scores, compared to those who did not (p = 0.05). Concurrently, a delay in starting DMARD was associated with a high erosive score (p = 0.023, r = 0.348). However, after adjustment for the delay in starting DMARD, SE was no longer significantly associated with the erosive score.
CONCLUSIONS:
In these patients, the delay in starting DMARDs had a greater influence on the erosive score than SE alone. Whilst we cannot discount the contribution of the SE presence, we would advocate early usage of DMARDs in every RA patient to reduce joint erosions and future disability.
OBJECTIVE: Interleukin-1 receptor antagonist (IL-1Ra) acts as an inhibitor of IL-1; which is one of the culprit cytokines in rheumatoid arthritis (RA). Although +2018 polymorphism of IL-1Ra has been implicated in the pathogenesis of RA, its importance remains poorly understood. Hence, the purpose of this study was to determine the clinical significance of interleukin-1 receptor antagonist (IL-1Ra) +2018 polymorphism in RA.
METHODS: Polymerase chain reaction (PCR) and sequencing were used to determine the genotypes of the IL-1Ra +2018 for 77 RA patients and 18 healthy controls. All RA patients were assessed for the disease activity score that includes 28 joints (DAS28) and radiographic disease damage based on Modified Sharp Score (MSS).
RESULTS: The frequency of the T/T and C/T genotypes did not differ significantly (p = 0.893) between the RA patients and the controls. The C/T genotype had significantly higher mean disease activity (DAS 28) and disease damage (MSS) scores with p values of 0.017 and 0.004, respectively. Additionally, the ESR (erythrocyte sedimentation rate), CRP (C-reactive protein), the number of swollen and tender joints were higher for the C/T individuals. On multivariate analysis the CRP, swollen joint count and MSS remained significant with the following p values i.e. 0.045, 0.046 and less than 0.05.
CONCLUSIONS: C/T genotype of IL-1Ra +2018 prognosticates more aggressive disease in RA.
Study site: Outpatient clinic, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
Worldwide population studies have generally agreed that rheumatoid arthritis (RA) is associated with a group of HLA-DRB1 alleles which share a common amino acid sequence at residues 70-74. This represents the first study to investigate the association of HLA-DRB1 genes with susceptibility to RA amongst Malay, Chinese and Indian ethnic groups in Malaysia. One hundred and thirty three RA patients and one hundred and sixty seven healthy controls were recruited. The HLA-DRB1 alleles were studied using the Phototyping method. The subtypes of HLA-DR4 were detected by "high resolution" PCR-SSP DRB1*04 typing techniques. The prevalence of HLA-DRB1*0405 was significantly higher in Malay patients with RA than in healthy controls (28.9 vs. 8.3%, p = 0.0016, OR = 4.48, 95% CI = 1.26-16.69). Similarly, DRB1*0405 was more common in Chinese RA patients than in controls (30.0 vs. 6.7%, p = 0.0029, OR = 6.00, 95% CI = 1.67-23.48). In addition, DRB1*0901 was a predisposing factor (32.0 vs. 6.7%,p = 0.0015, OR = 6.59, 95% CI = 1.85-25.64) and *0301/04 had a protective role (4.0vs. 25.0%, p = 0.00562, OR = 0.13, 95% CI = 0.02-0.62) in Malaysian Chinese RA. RA in Indians was associated with DRB1*1001 (51.1 vs. 8.5%,p = 0.00002, OR = 11.24, 95% CI = 3.13-44.18). DRB1*0701 (13.3 vs. 42.6%,p = 0.0022, OR = 2.73, 95% CI = 1.40-5.37) may have a protective effect. Therefore, in the Malaysian population, RA is primarily associated with the QRRAA motif, and we suggest that genetic factors play a crucial role in the pathogenesis of RA, compared to environmental factors.
Pain is the most common symptom reported by patients with rheumatoid arthritis (RA) even after the resolution of chronic joint inflammation. It is believed that RA-associated pain is not solely due to inflammation, but could also be attributed to aberrant modifications to the central nervous system. The P2X4 receptor (P2X4R) is an ATP-activated purinergic receptor that plays a significant role in the transmission of information in the nervous system and pain. The involvement of P2X4R during the pathogenesis of chronic inflammatory pain and neuropathic pain is well-established. The attenuation of this receptor alleviates disease pathogenesis and related symptoms, including hyperalgesia and allodynia. Although some studies have revealed the contribution of P2X4R in promoting joint inflammation in RA, how it implicates pain associated with RA at peripheral and central nervous systems is still lacking. In this review, the possible contributions of P2X4R in the nervous system and how it implicates pain transmission and responses were examined.
OBJECTIVES: Dendritic cell immunoreceptor (DCIR) has been implicated in development of autoimmune disorders in rodent and DCIR polymorphisms were associated with anti-citrullinated proteins antibodies (ACPA)-negative rheumatoid arthritis (RA) in Swedish Caucasians. This study was undertaken to further investigate whether DCIR polymorphisms are also risk factors for the development of RA in four Asian populations originated from China and Malaysia.
METHODS: We genotyped two DCIR SNPs rs2377422 and rs10840759 in Han Chinese population (1,193 cases, 1,278 controls), to assess their association with RA. Subsequently, rs2377422 was further genotyped in three independent cohorts of Malaysian-Chinese subjects (MY_Chinese, 254 cases, 206 controls), Malay subjects (MY_ Malay, 515 cases, 986 controls), and Malaysian-Indian subjects (MY_Indian, 378 cases, 285 controls), to seek confirmation of association in various ethnic groups. Meta-analysis was preformed to evaluate the contribution of rs2377422 polymorphisms to the development of ACPA-negative RA in distinct ethnic groups. Finally, we carried out association analysis of rs2377422 polymorphisms with DCIR mRNA expression levels.
RESULTS: DCIR rs2377422 was found to be significantly associated with ACPA -negative RA in Han Chinese (OR 1.92, 95% CI 1.27-2.90, P=0.0020). Meta-analysis confirms DCIR rs2377422 as a risk factor for ACPA-negative RA across distinct ethnic groups (OR(overall) =1.17, 95% CI 1.06-1.30, P=0.003). The SNP rs2377422 polymorphism showed significant association with DCIR mRNA expression level, i.e. RA-risk CC genotype exhibit a significant increase in the expression of DCIR (P=0.0023, Kruskal-Wallis).
CONCLUSIONS: Our data provide evidence for association between DCIR rs2377422 and RA in non-Caucasian populations and confirm the influence of DCIR polymorphisms on RA susceptibility, especially on ACPA-negative RA.
In this study, three single nucleotide polymorphisms (SNPs) located within the promoter of the human interleukin (IL)-10 gene [rs1800896 (position: -1087G>A), rs1800871 (position: -824C>T) and rs1800872 (position: -597C>A)] were investigated in 84 rheumatoid arthritis (RA) patients and 95 age- and sex-matched healthy subjects using polymerase chain reaction-restriction fragment length polymorphism method. Production of IL-10 by peripheral blood lymphocytes from the RA patients and healthy subjects cultured in the presence of Concanavalin A (Con A) was determined by using enzyme-linked immunosorbent assay. The results show that the distribution of the IL-10 genotypes did not differ significantly between RA patients and healthy subjects (P>0.05). However, a significant difference was observed in allele frequencies of -824CT, -824TT, -597CA, and -597AA between the RA patients and healthy volunteers (P=0.04). The -1087A/-824T/-597A (ATA) haplotype, which comprises all mutant alleles, was associated with lower IL-10 production when compared with the other haplotypes. In contrast, the RA patients who did not display the ATA haplotype produced significantly higher levels of IL-10 when compared with those carrying either one (P=0.012) or two (P=0.005) ATA haplotypes. Our findings suggest that there is an association between SNPs in the promoter of the human IL-10 gene and susceptibility to RA.
Study site: Hospital Tuanku Ja’afar, (Hospital Seremban), Seremban, Negeri Sembilan, Malaysia
Rheumatoid arthritis (RA) is a chronic arthritic condition that can lead to deformities and disabilities. Although numerous studies reported the association of human leukocyte antigen (HLA)-DRB1*04 and RA, other genes, e.g. cytokines genes, may contribute towards disease susceptibility. Interleukin-18 (IL-18) is a proinflammatory cytokine postulated to play a role in the acute and chronic inflammatory phases of RA. The IL-18 protein expression seems to be regulated by two single-nucleotide polymorphisms (SNPs) located at positions -607 and -137 in the promoter region of the gene. It is postulated that specific alleles may be associated with susceptibility to the development of RA. In the present study, we described the IL-18 gene promoter region genotypes and combined genotypes (-607/-137) in 106 RA patients and 273 unrelated healthy controls to evaluate the contributions of these alleles to RA predisposition in Chinese, Malays, and Indians. The genotyping were performed using sequence-specific polymerase chain reactions. Rheumatoid factors were assayed by enzyme-linked immunosorbent assay. Biodata were obtained through chart review. The controls had significantly higher frequency of AA genotype at position -607 when compared to RA patients. No significant differences were observed in the distribution of either allelic or genotypic frequencies at position -137. There was no association between the genotypes and the presence of rheumatoid factors. This study did not find evidence of a genetic susceptibility factor but demonstrated the novel finding that the AA genotype at position -607 is associated with a protective effect against development of RA in Chinese individuals. This protection may be mediated through inhibition of cyclic (Adenosine 3', 5'-cyclic monophosphate) AMP-responsive element (CRE)-binding protein by the disruption of the CRE consensus sequence.
Survivin is a biomarker of cancer known for its anti-apoptotic and cell-cycle regulating properties. In the context of non-cancer pathology, high levels of survivin may be measured in blood and synovial fluid of patients with rheumatoid arthritis (RA) and associate with early joint damage and poor therapy response. The aim of the study was to investigate the value of survivin measurements in blood for diagnosis of RA in the frame of the Malaysian epidemiological investigation of rheumatoid arthritis (MyEIRA) study. The study enrolled RA patients from eight rheumatology centres in Peninsular Malaysia. The healthy controls matched by age, gender and ethnicity were recruited on the community basis from the residential area of the patients. Levels of survivin were measured in blood of RA patients (n = 1233) and controls (n = 1566) by an enzyme-linked immuno-sorbent assay (ELISA). The risk for RA was calculated as odds ratio (OR) and 95% confidence intervals in the individuals with high levels of survivin. The risk was calculated in relation to antibodies against cyclic citrullinated peptides (ACPA), detected by ELISA and HLA-DRB1 shared epitope (SE) alleles, identified by the polymerase chain reaction using sequence specific oligonucleotide method. High levels of survivin were detected in 625 of 1233 (50.7%) RA cases and in 85 of 1566 (5.4%) controls, indicating its high specificity for RA. Survivin was association with an increase in RA risk in the patients having neither SE-alleles nor ACPA (OR = 5.40, 95% CI 3.81-7.66). For the patients combining survivin, SE, and ACPA, the estimated risk for RA was 16-folds higher compared to the survivin negative patients with SE and ACPA(OR = 16.21, 95% CI 5.70-46.18). To conclude, detection of survivin in blood provides a simple test to improve diagnostic and to increase predictability for RA.
INTRODUCTION:Rheumatoid arthritis (RA) is a multifactorial autoimmune disease in which genetic and environmental factors interact in the etiology. In this study, we investigated whether smoking and HLA-DRB1 shared-epitope (SE) alleles interact differently in the development of the two major subgroups of rheumatoid arthritis (RA), anti-citrullinated proteins antibody (ACPA)-positive and ACPA-negative disease, in a multiethnic population of Asian descent.
METHODS: A case-control study comprising early diagnosed RA cases was carried out in Malaysia between 2005 and 2009. In total, 1,076 cases and 1,612 matched controls participated in the study. High-resolution HLA-DRB1 genotyping was performed for shared-epitope (SE) alleles. All participants answered a questionnaire on a broad range of issues, including smoking habits. The odds ratio (OR) of developing ACPA-positive and ACPA-negative disease was calculated for smoking and the presence of any SE alleles separately. Potential interaction between smoking history (defined as "ever" and "never" smoking) and HLA-DRB1 SE alleles also was calculated.
RESULTS: In our multiethnic study, both the SE alleles and smoking were associated with an increased risk of developing ACPA-positive RA (OR SE alleles, 4.7; 95% confidence interval (CI), 3.6 to 6.2; OR smoking, 4.1; 95% CI, 1.9 to 9.2). SE-positive smokers had an odds ratio of ACPA-positive RA of 25.6 (95% CI, 10.4 to 63.4), compared with SE-negative never-smokers. The interaction between smoking and SE alleles was significant (attributable proportion due to interaction (AP) was 0.7 (95% CI, 0.5 to 1.0)). The HLA-DRB1*04:05 SE allele, which is common in Asian populations, but not among Caucasians, was associated with an increased risk of ACPA-positive RA, and this allele also showed signs of interaction with smoking (AP, 0.4; 95% CI, -0.1 to 0.9). Neither smoking nor SE alleles nor their combination was associated with an increased risk of ACPA-negative RA.
CONCLUSIONS: The risk of developing ACPA-positive RA is associated with a strong gene-environment interaction between smoking and HLA-DRB1 SE alleles in a Malaysian multiethnic population of Asian descent. This interaction seems to apply also between smoking and the specific HLA-DRB1*04:05 SE allele, which is common in Asian populations but not in Caucasians.
INTRODUCTION: The majority of our knowledge regarding disease-related mechanisms of uncontrolled citrullination and anti-citrullinated protein antibody development in rheumatoid arthritis (RA) was investigated in Caucasian populations. However, peptidylarginine deiminase (PADI) type 4 gene polymorphisms are associated with RA in East Asian populations and weak or no association was found in Caucasian populations. This study explores the association between the PADI4 polymorphisms and RA risk in a multiethnic population residing in South East Asia with the goal of elucidating generalizability of association in non-Caucasian populations.
METHODS: A total of 320 SNPs from the PADI locus (including PADI1, PADI2, PADI3, PADI4 and PADI6 genes) were genotyped in 1,238 RA cases and 1,571 control subjects from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) case-control study. Additionally, we conducted meta-analysis of our data together with the previously published studies of RA from East Asian populations.
RESULTS: The overall odds ratio (ORoverall) for the PADI4 (rs2240340) allelic model was 1.11 (95% confidence interval (CI) = 1.00 to 1.23, P = 0.04) and for the genotypic model was 1.20 (95% CI = 1.01 to 1.44, P = 0.04). Haplotype analysis for four selected PADI4 SNPs revealed a significant association of one with susceptibility (P = 0.001) and of another with a protective effect (P = 0.02). The RA susceptibility was further confirmed when combined meta-analysis was performed using these data together with data from five previously published studies from Asia comprising 5,192 RA cases and 4,317 control subjects (ORoverall = 1.23 (95% CI = 1.16 to 1.31, Pheterogeneity = 0.08) and 1.31 (95% CI = 1.20 to 1.44, Pheterogeneity = 0.32) in allele and genotype-based models, respectively). In addition, we also detected a novel association of PADI2 genetic variant rs1005753 with RA (ORoverall = 0.87 (95% CI = 0.77 to 0.99)).
CONCLUSION: Our study demonstrates an association between PADI4 and RA in the multiethnic population from South East Asia and suggests additional association with a PADI2 gene. The study thus provides further support for the notion that polymorphisms in genes for enzymes responsible for citrullination contribute to RA development in multiple populations of Asian descent.
BACKGROUND: Multiple factors, including interactions between genetic and environmental risks, are important in susceptibility to rheumatoid arthritis (RA). However, the underlying mechanism is not fully understood. This study was undertaken to evaluate whether DNA methylation can mediate the interaction between genotype and smoking in the development of anti-citrullinated peptide antibody (ACPA)-positive RA.
METHODS: We investigated the gene-smoking interactions in DNA methylation using 393 individuals from the Epidemiological Investigation of Rheumatoid Arthritis (EIRA). The interaction between rs6933349 and smoking in the risk of developing ACPA-positive RA was further evaluated in a larger portion of the EIRA (1119 controls and 944 ACPA-positive patients with RA), and in the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) (1556 controls and 792 ACPA-positive patients with RA). Finally, mediation analysis was performed to investigate whether DNA methylation of cg21325723 mediates this gene-environment interaction on the risk of developing of ACPA-positive RA.
RESULTS: We identified and replicated one significant gene-environment interaction between rs6933349 and smoking in DNA methylation of cg21325723. This gene-smoking interaction is a novel interaction in the risk of developing ACPA-positive in both Caucasian (multiplicative P value = 0.056; additive P value = 0.016) and Asian populations (multiplicative P value = 0.035; additive P value = 0.00027), and it is mediated through DNA methylation of cg21325723.
CONCLUSIONS: We showed that DNA methylation of cg21325723 can mediate the gene-environment interaction between rs6933349 and smoking, impacting the risk of developing ACPA-positive RA, thus being a potential regulator that integrates both internal genetic and external environmental risk factors.
OBJECTIVES: Lung exposures including cigarette smoking and silica exposure are associated with the risk of rheumatoid arthritis (RA). We investigated the association between textile dust exposure and the risk of RA in the Malaysian population, with a focus on women who rarely smoke.
METHODS: Data from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis population-based case-control study involving 910 female early RA cases and 910 female age-matched controls were analysed. Self-reported information on ever/never occupationally exposed to textile dust was used to estimate the risk of developing anti-citrullinated protein antibody (ACPA)-positive and ACPA-negative RA. Interaction between textile dust and the human leucocyte antigen DR β-1 (HLA-DRB1) shared epitope (SE) was evaluated by calculating the attributable proportion due to interaction (AP), with 95% CI.
RESULTS: Occupational exposure to textile dust was significantly associated with an increased risk of developing RA in the Malaysian female population (OR 2.8, 95% CI 1.6 to 5.2). The association between occupational exposure to textile dust and risk of RA was uniformly observed for the ACPA-positive RA (OR 2.5, 95% CI 1.3 to 4.8) and ACPA-negative RA (OR 3.5, 95% CI 1.7 to 7.0) subsets, respectively. We observed a significant interaction between exposure to occupational textile dust and HLA-DRB1 SE alleles regarding the risk of ACPA-positive RA (OR for double exposed: 39.1, 95% CI 5.1 to 297.5; AP: 0.8, 95% CI 0.5 to 1.2).
CONCLUSIONS: This is the first study demonstrating that textile dust exposure is associated with an increased risk for RA. In addition, a gene-environment interaction between HLA-DRB1 SE and textile dust exposure provides a high risk for ACPA-positive RA.