Advances in the genomics of ANCA-associated vasculitis-a view from East Asia.

Recent genome-wide association studies (GWAS) in populations of European ancestry have identified several susceptibility genes to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The most significant association was observed in HLA-DP variants in granulomatosis with polyangiitis and proteinase 3 (PR3)-ANCA positive vasculitis, while HLA-DQ variants were strongly associated with microscopic polyangiitis (MPA) and myeloperoxidase (MPO)-ANCA positive vasculitis (MPO-AAV). In non-HLA genes, SERPINA1, PRTN3 and PTPN22 were identified as susceptibility genes to AAV. The observations in GWAS suggested the presence of shared and non-shared susceptibility genes among AAV subsets. Epidemiological features of AAV are strikingly different in the East Asian populations; the proportions of MPO-AAV among total AAV, MPO-ANCA positive patients among GPA, and patients with interstitial lung disease among total AAV are considerably higher in Japan as compared with Europe. Such population differences suggest the critical role for genetic background behind these conditions. Although no GWAS has been reported in the Asian populations so far, the association of HLA-class II alleles with MPA and MPO-AAV was identified. Future genomics studies on AAV, especially from Asian populations, will provide valuable information to elucidate the molecular mechanisms and to identify molecular targets for AAV.

MUC5B Promoter Variant and Rheumatoid Arthritis with Interstitial Lung Disease.

BACKGROUND: Given the phenotypic similarities between rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) (hereafter, RA-ILD) and idiopathic pulmonary fibrosis, we hypothesized that the strongest risk factor for the development of idiopathic pulmonary fibrosis, the gain-of-function MUC5B promoter variant rs35705950, would also contribute to the risk of ILD among patients with RA. METHODS: Using a discovery population and multiple validation populations, we tested the association of the MUC5B promoter variant rs35705950 in 620 patients with RA-ILD, 614 patients with RA without ILD, and 5448 unaffected controls. RESULTS: Analysis of the discovery population revealed an association of the minor allele of the MUC5B promoter variant with RA-ILD when patients with RA-ILD were compared with unaffected controls (adjusted odds ratio, 3.8; 95% confidence interval [CI], 2.8 to 5.2; P=9.7×10-17). The MUC5B promoter variant was also significantly overrepresented among patients with RA-ILD, as compared with unaffected controls, in an analysis of the multiethnic case series (adjusted odds ratio, 5.5; 95% CI, 4.2 to 7.3; P=4.7×10-35) and in a combined analysis of the discovery population and the multiethnic case series (adjusted odds ratio, 4.7; 95% CI, 3.9 to 5.8; P=1.3×10-49). In addition, the MUC5B promoter variant was associated with an increased risk of ILD among patients with RA (adjusted odds ratio in combined analysis, 3.1; 95% CI, 1.8 to 5.4; P=7.4×10-5), particularly among those with evidence of usual interstitial pneumonia on high-resolution computed tomography (adjusted odds ratio in combined analysis, 6.1; 95% CI, 2.9 to 13.1; P=2.5×10-6). However, no significant association with the MUC5B promoter variant was observed for the diagnosis of RA alone. CONCLUSIONS: We found that the MUC5B promoter variant was associated with RA-ILD and more specifically associated with evidence of usual interstitial pneumonia on imaging. (Funded by Société Française de Rhumatologie and others.).

Association of functional (GA)n microsatellite polymorphism in the FLI1 gene with susceptibility to human systemic sclerosis.

OBJECTIVE: Susceptibility genes that can account for characteristic features of SSc such as fibrosis, vasculopathy and autoimmunity remain to be determined. In mice, deficiency of Friend leukaemia integration 1 transcription factor (Fli1) causes SSc-like disease with these features. The human FLI1 gene contains (GA)n microsatellite, which has been shown to be associated with expression level. Because microsatellite polymorphisms are difficult to capture by genome-wide association studies, we directly genotyped FLI1 (GA)n microsatellite and examined its association with SSc. METHODS: Genomic DNA from 639 Japanese SSc patients and 851 healthy controls was genotyped for (GA)n microsatellite using the fragment assay. The cut-off repeat number for susceptibility to SSc was determined by receiver operating characteristics (ROC) analysis. Association with susceptibility and clinical characteristics was examined using logistic regression analysis. FLI1 mRNA levels were determined using quantitative RT-PCR. RESULTS: Based on the ROC analysis, (GA)n alleles with ≥22 repeats were collectively defined as L alleles and alleles with ≤21 repeats as S alleles. (GA)n L alleles were significantly associated with susceptibility to SSc (P = 5.0e-04, odds ratio 1.34, additive model). Significant association was observed both in diffuse cutaneous and limited cutaneous SSc. Among the SSc, (GA)n L alleles were significantly enriched in the patients with a modified Rodnan total skin thickness score ≥10 compared with those with a score <10. FLI1 mRNA levels were significantly decreased in healthy controls carrying (GA)n L alleles as compared with non-carriers. CONCLUSION: Extended repeat alleles of FLI1 (GA)n microsatellite may be associated with lower FLI1 mRNA levels and susceptibility to human SSc.

Human leukocyte antigen in Japanese patients with idiopathic inflammatory myopathy.

Objective: The human leukocyte antigen (HLA) is the strongest genetic risk factor for idiopathic inflammatory myopathy (IIM), and different HLA alleles have been reported to be associated with IIM susceptibility among different ethnic groups. In this study, we have investigated HLA alleles associated with IIM in Japanese patients.Methods: Genotyping of HLA-DRB1 and DPB1 were performed in 252 Japanese IIM patients (166 dermatomyositis [DM] and 86 polymyositis [PM] patients) and the association was analyzed with comparison to controls (n = 1026 for DRB1 and n = 413 for DPB1).Results: DRB1*08:03 was associated with IIM (p = 1.60 × 10-5, pc = .0005, odds ratio [OR] 2.11, 95% confidence interval [CI] 1.52-2.92) and DM (p = .0004, pc = .0128, OR 2.06, 95%CI 1.40-3.02). DPB1*05:01 was also associated with IIM (p = .0001, pc = .0021, OR 1.96, 95%CI 1.38-2.77) and DM (p = .0005, pc = .0075, OR 2.05, 95%CI 1.37-3.08). DRB1*09:01 (p = .0012, pc = .0368, OR 0.35, 95% CI 0.18-0.69) and DPB1*04:01(p = .0004, pc = .0057, OR 0.05, 95% CI 0.00-0.85) were protectively associated with PM. Two locus analyses suggested that DRB1*09:01 and DPB1*04:01 were independently associated with PM.Conclusion: Protective associations of HLA were detected in Japanese PM patients.

HLA-DQB1 DPB1 alleles in Japanese patients with adult-onset Still's disease.

Objective: HLA class II alleles are major determinants of genetic predisposition to rheumatic diseases. Predisposing effects of HLA had been suggested in AOSD, however, ethnic differences may account for variations in AOSD association with HLA. We determined the contribution of HLA-DQB1, DPB1 alleles to susceptibility to Adult-onset Still's disease (AOSD) in the Japanese population. Methods: HLA-DQB1 and DPB1 alleles were analyzed in 87 Japanese patients with AOSD and 413 Japanese healthy subjects. Results: We found significant association between HLA-DQB1*06:02 (Pc = 0.010, odds ratio: 2.54) and AOSD, whereas there was no association between the DQB1*06:02 allele and disease phenotypes of AOSD. Moreover, we did not find a predisposing effect of the HLA-DPB1 allele to AOSD. Haplotype analysis showed that presence of DRB1*15:01-DQB1*06:02 was associated with Japanese patients with AOSD. However, conditional logistic regression tests were unable to demonstrate independent association between DRB1*1501 or DQB1*0602 and AOSD. Conclusions: Our results show significant association between AOSD and the HLA DQB1*06:02 allele, and between the DRB1*1501-DQB1*06:02 haplotype and AOSD susceptibility. These findings suggest that genetic susceptibility to AOSD depends on the genotype combinations of HLA DRB1 and DQB1 alleles.

Association of a single nucleotide polymorphism in TNIP1 with type-1 autoimmune hepatitis in the Japanese population.

Several studies reported that autoimmune diseases share a number of susceptibility genes. Of these genes, a SNP rs7708392 in TNIP1 was reported to be associated with systemic lupus erythematosus (SLE). Autoimmune hepatitis (AIH), a rare chronic progressive liver disease, shares some clinical features with SLE. Therefore, we investigated whether the SNP is associated with Japanese AIH. An association study of rs7708392 was conducted in 343 Japanese AIH patients and 828 controls. We found that rs7708392 is associated with AIH (P = 0.0236, odds ratio (OR) 1.26, 95% confidence interval (CI): 1.03-1.54), under the allele model for C allele. Significant differences of clinical characteristics of the AIH patients with or without G allele of rs7708392 were not detected. Of interest, the association was stronger in AIH without HLA-DRB1*04:05 allele (P = 0.0063, Q = 0.0127, OR 1.48, 95% CI: 1.12-1.96), though the association was not detected in AIH with DRB1*04:05. The C allele of rs7708392 was associated with AIH, especially AIH without DRB1*04:05, an already established risk factor.

Association of ETS1 polymorphism with granulomatosis with polyangiitis and proteinase 3-anti-neutrophil cytoplasmic antibody positive vasculitis in a Japanese population.

ETS proto-oncogene 1, transcription factor (ETS1) is involved in various immune responses. Genome-wide association studies on systemic lupus erythematosus in Chinese populations identified the association of ETS1 polymorphism in 3' untranslated region, rs1128334A, which was associated with lower ETS1 expression. In view of substantial sharing of susceptibility genes across multiple autoimmune diseases, we examined whether ETS1 is associated with a rare autoimmune rheumatic disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Association of rs1128334 was tested in 466 Japanese patients with AAV and 1099 healthy controls by logistic regression analysis under the additive model. AAV patients were classified into 285 microscopic polyangiitis (MPA), 92 granulomatosis with polyangiitis (GPA), 56 eosinophilic GPA, and 33 unclassifiable AAV, according to the European Medicines Agency (EMEA) algorithm. Among the patients, 376 were positive for MPO-ANCA and 62 for PR3-ANCA. When the patients were classified according to the EMEA classification, rs1128334A allele was significantly increased in GPA (P = 0.0060, P c = 0.030, odds ratio (OR), 1.54; 95% confidence interval (CI), 1.13-2.10). With respect to the ANCA specificity, significant association was observed in PR3-ANCA positive AAV (P = 0.0042, P c = 0.021, OR, 1.72; 95% CI, 1.19-2.49). In conclusion, ETS1 polymorphism was suggested to be associated with GPA and PR3-ANCA positive AAV in a Japanese population.

Biomarker for nontuberculous mycobacterial pulmonary disease in patients with rheumatoid arthritis: Anti-glycopeptidolipid core antigen immunoglobulin A antibodies.

OBJECTIVE: Nontuberculous mycobacterial (NTM) pulmonary disease is occasionally associated with rheumatoid arthritis (RA), influencing the therapeutic strategy of RA. Since chronic lung diseases are frequently associated with RA, the diagnosis of NTM pulmonary disease is quite difficult in RA patients. Recently, a serological diagnostic test detecting serum immunoglobulin A against the glycopeptidolipid (GPL) core antigen was developed. We investigated the serum levels of anti-GPL antibodies in RA patients to determine the usefulness for detecting NTM pulmonary disease. METHODS: Anti-GPL antibodies were detected in the sera from RA patients with or without NTM pulmonary disease. RESULTS: The positivity of anti-GPL antibodies in RA patients with NTM pulmonary disease was higher than in RA without (p = 1.76 × 10-14, odds ratio 70.29, 95% confidence interval [CI] 22.28-221.83). Anti-GPL Ab titers were increased in RA with NTM pulmonary disease (mean titer ± standard deviation [U/ml], RA with NTM pulmonary disease: 4.1 ± 7.0, RA without NTM pulmonary disease: 0.4 ± 1.6, p = 1.51 × 10-10). The area under the curve (AUC) value of the receiver operating characteristic (ROC) curve for anti-GPL antibodies was 0.917 (95%CI 0.860-0.974, p = 3.32 × 10-47). CONCLUSIONS: Serum anti-GPL antibodies are useful for detecting NTM pulmonary disease in RA patients.

Transethnic meta-analysis identifies GSDMA and PRDM1 as susceptibility genes to systemic sclerosis.

OBJECTIVES: Systemic sclerosis (SSc) is an autoimmune disease characterised by skin and systemic fibrosis culminating in organ damage. Previous genetic studies including genome-wide association studies (GWAS) have identified 12 susceptibility loci satisfying genome-wide significance. Transethnic meta-analyses have successfully expanded the list of susceptibility genes and deepened biological insights for other autoimmune diseases. METHODS: We performed transethnic meta-analysis of GWAS in the Japanese and European populations, followed by a two-staged replication study comprising a total of 4436 cases and 14 751 controls. Associations between significant single nuclear polymorphisms (SNPs) and neighbouring genes were evaluated. Enrichment analysis of H3K4Me3, a representative histone mark for active promoter was conducted with an expanded list of SSc susceptibility genes. RESULTS: We identified two significant SNP in two loci, GSDMA and PRDM1, both of which are related to immune functions and associated with other autoimmune diseases (p=1.4×10-10 and 6.6×10-10, respectively). GSDMA also showed a significant association with limited cutaneous SSc. We also replicated the associations of previously reported loci including a non-GWAS locus, TNFAIP3. PRDM1 encodes BLIMP1, a transcription factor regulating T-cell proliferation and plasma cell differentiation. The top SNP in GSDMA was a missense variant and correlated with gene expression of neighbouring genes, and this could explain the association in this locus. We found different human leukocyte antigen (HLA) association patterns between the two populations. Enrichment analysis suggested the importance of CD4-naïve primary T cell. CONCLUSIONS: GSDMA and PRDM1 are associated with SSc. These findings provide enhanced insight into the genetic and biological basis of SSc.

Association of a single nucleotide polymorphism upstream of ICOS with Japanese autoimmune hepatitis type 1.

Autoimmune hepatitis (AIH) is an uncommon chronic autoimmune liver disease. Several studies reported the association of polymorphisms between CD28, CTLA4 and ICOS gene cluster in 2q33.2 with autoimmune or inflammatory diseases. The previous genome-wide association study on type 1 AIH in a European population has reported a risk G allele of a single nucleotide polymorphism (SNP), rs4325730, in this region. Here, we conducted an association study of this SNP with type 1 AIH in a Japanese population, as a replication study.An association study of rs4325730 was conducted in 343 Japanese AIH patients and 315 controls.We found that rs4325730 is associated with AIH (P=0.0173, odds ratio (OR) 1.30, 95% confidence interval (CI) 1.05-1.62, under the allele model for G allele, P=0.0070, OR 1.62, 95% CI 1.14-2.31, under the dominant model for G allele). This SNP was strongly associated with definite AIH (P=0.0134, OR 1.36, 95% CI 1.07-1.74; under allele model for G, P=0.0035, OR 1.85, 95% CI 1.22-2.81, under dominant model for G).This is the first replication association study of rs4325730 upstream of ICOS with AIH in the Japanese population and rs4325730G is a risk allele.

Plasma miRNA expression profiles in rheumatoid arthritis associated interstitial lung disease.

BACKGROUND: Interstitial lung disease (ILD) is frequently associated with rheumatoid arthritis (RA), and is designated RA-associated ILD (RA-ILD). RA-ILD has a large impact on the prognosis of RA. Here, we investigated the micro RNAs (miRNAs) profiles to determine whether they may be useful for diagnosing RA-ILD. METHODS: RNA was isolated from plasma samples and cDNA was synthesized. Real-time RT-PCR analysis was performed to evaluate 752 miRNA expression profiles in plasma pools from RA patients with or without RA-ILD. Sixteen selected miRNA levels were analyzed in individual plasmas from 64 RA patients with or without RA-ILD. RESULTS: Expression levels of hsa-miR-214-5p (mean relative expression level ± standard deviation, 8.1 ± 28.2 in RA with ILD, 0.2 ± 0.9 in RA without ILD, P = 0.0156) and hsa-miR-7-5p (56.2 ± 260.4 in RA with ILD, 4.7 ± 11.8 in RA without ILD, P = 0.0362) were higher in RA patients with RA-ILD than in those without. The values of miRNA index (214, 7) generated from hsa-miR-214-5p and hsa-miR-7-5p for ILD were significantly elevated in RA patients with RA-ILD compared with those without (0.122 ± 0.332 in RA with ILD, 0.006 ± 0.013 in RA without ILD, P = 0.0010). The area under the curve value of the receiver operating characteristic curve for the miRNA index (214, 7) was 0.740. CONCLUSIONS: To the best of our knowledge, this is the first report of miRNA profiles in RA-ILD. The expression levels of hsa-miR-214-5p and hsa-miR-7-5p were increased in RA with ILD.

Association of BAK1 single nucleotide polymorphism with a risk for dengue hemorrhagic fever.

BACKGROUND: Dengue hemorrhagic fever (DHF) is a severe life-threatening form of dengue infection. Low platelet count is one of the characteristic clinical manifestations in patients with severe dengue. However, little is known about genetic factors in the host that cause low platelet count in patients with dengue. METHODS: A previous genome-wide association study of hematological and biochemical traits identified single nucleotide polymorphisms (SNPs) associated with low platelet count in healthy subjects. To examine the possible association of these SNPs with DHF, 918 Thai patients with dengue [509 patients with DHF and 409 with dengue fever (DF)] were genotyped for five SNPs: rs5745568 in BAK1, rs6141 in THPO, rs6065 in GP1BA, rs739496 in SH2B3, and rs385893 in RCL1. In addition, rs4804803 in CD209, that has been reported to be associated with dengue infection, was also genotyped to examine if rs4804803 affects the association detected in this study. RESULTS: The allele frequencies of each SNP were compared between the DHF and DF groups. Among the five SNPs, the G allele of rs5745568 in BAK1 was significantly associated with a risk for DHF [P = 0.006 and crude odd ratio (95 % confidence interval) = 1.32 (1.09-1.60)]. The association of this allele with DHF was also significant in a logistic regression analysis adjusted for age, sex, hospital (i.e., geographic region), immune status (i.e., primary or secondary infection), and virus serotype [P = 0.016 and adjusted odd ratio (95 % confidence interval) = 1.29 (1.05-1.58)]. The result was not influenced by rs4804803 [P = 0.0167 and adjusted OR (95 % CI) = 1.29 (1.05-1.58)]. No other SNPs including rs4804803 showed significant association. CONCLUSIONS: The low-level constitutive production of platelets caused by the G allele of rs5745568 seems to increase the risk of bleeding in dengue infection. Our results suggest that BCL-2 homologous antagonist/killer (BAK) protein, encoded by BAK1, plays a crucial role in the pathogenesis of DHF.

Association of human leukocyte antigen alleles with chronic lung diseases in rheumatoid arthritis.

OBJECTIVES: Chronic lung diseases including interstitial lung disease and airway disease (AD) occur in RA patients. Interstitial lung disease and AD in RA are extra-articular manifestations that influence the prognosis quoad vitam of RA. Studies on associations of HLA alleles with RA have been carried out, and shared epitopes of several alleles are reported to be associated with RA susceptibility. Few association studies in RA subpopulations with chronic lung diseases have been conducted. The aim of the study was to identify HLA alleles predisposing to RA phenotypes including the presence of AD. METHODS: Associations of HLA-DRB1 and DQB1 alleles with chronic lung diseases in RA were analysed. RESULTS: A positive association was found between the DR4 serological group and resistance to usual interstitial pneumonia [P = 0.0250, odds ratio (OR) 0.62, 95% CI: 0.41, 0.93]. The DR2 serological group was associated with susceptibility to usual interstitial pneumonia (P = 0.0036, OR = 1.86, 95% CI: 1.23, 2.81). An association was found for shared epitopes alleles with bronchiolitic AD (P = 0.0040, OR = 2.06, 95% CI: 1.24, 3.41). DQB1*03:01 was associated with bronchiectatic AD (P = 0.0021, corrected P-value (Pc) = 0.0315, OR = 1.99, 95% CI: 1.30, 3.06), as well as with emphysema (P = 0.0007, Pc = 0.0104, OR = 2.43, 95% CI: 1.49, 3.95). In combined analysis, a predisposing association of DQB1*03:01 (P = 1.94 ×10(-5), Pc = 0.0003, OR = 2.16, 95% CI: 1.53, 3.06) and a negative association of DQB1*03:02 (P = 0.0008, Pc = 0.0117, OR = 0.33, 95% CI: 0.17, 0.67) with bronchiectatic AD or emphysema were observed in RA. CONCLUSION: The present study identified an association of HLA-DQB1*03:01 with predisposition to, and DQB1*03:02 with resistance to, bronchiectatic AD or emphysema in RA.

Identification of secreted phosphoprotein 1 gene as a new rheumatoid arthritis susceptibility gene.

OBJECTIVE: To evaluate the contribution of the SPP1 rs11439060 and rs9138 polymorphisms, previously reported as autoimmune risk variants, in the rheumatoid arthritis (RA) genetic background according to anti-citrullinated protein antibodies (ACPAs) status of RA individuals. METHODS: We analysed a total of 11,715 RA cases and 26,493 controls from nine independent cohorts; all individuals were genotyped or had imputed genotypes for SPP1 rs11439060 and rs9138. The effect of the SPP1 rs11439060 and rs9138 risk-allele combination on osteopontin (OPN) expression in macrophages and OPN serum levels was investigated. RESULTS: We provide evidence for a distinct contribution of SPP1 to RA susceptibility according to ACPA status: the combination of ≥3 SPP1 rs11439060 and rs9138 common alleles was associated mainly with ACPA negativity (p=1.29×10(-5), ORACPA-negative 1.257 (1.135 to 1.394)) and less with ACPA positivity (p=0.0148, ORACPA-positive 1.072 (1.014 to 1.134)). The ORs between these subgroups (ie, ACPA-positive and ACPA-negative) significantly differed (p=7.33×10(-3)). Expression quantitative trait locus analysis revealed an association of the SPP1 risk-allele combination with decreased SPP1 expression in peripheral macrophages from 599 individuals. To corroborate these findings, we found an association of the SPP1 risk-allele combination and low serum level of secreted OPN (p=0.0157), as well as serum level of secreted OPN correlated positively with ACPA production (p=0.005; r=0.483). CONCLUSIONS: We demonstrate a significant contribution of the combination of SPP1 rs11439060 and rs9138 frequent alleles to risk of RA, the magnitude of the association being greater in patients negative for ACPAs.

A replication study confirms the association of GWAS-identified SNPs at MICB and PLCE1 in Thai patients with dengue shock syndrome.

BACKGROUND: Dengue shock syndrome (DSS), a severe life-threatening form of dengue infection, mostly occurs in children. A recent genome wide association study (GWAS) identified two SNPs, rs3132468 of major histocompatibility complex class I polypeptide-related sequence B (MICB) and rs3765524 of phospholipase C, epsilon 1 (PLCE1), associated with DSS in Vietnamese children. In this study, to examine whether an identical association is found in a different population, the association of these two SNPs with DSS was assessed in Thai children with dengue. METHODS: The rs3132468 and rs3765524 SNPs were genotyped in 917 Thai children with dengue: 76 patients with DSS and 841 patients with non-DSS. The allele frequencies were compared between DSS and non-DSS groups by one-sided Fisher's exact test. The association of rs3132468 and rs3765524 with the mRNA expression levels of MICB and PLCE1 were assessed in EBV-transformed lymphoblastoid cell lines. RESULTS: The reported DSS-risk alleles were significantly associated with DSS in Thai patients with dengue (one-sided P = 0.0213 and odds ratio [OR] = 1.58 for rs3132468-C and one-sided P = 0.0252 and OR = 1.49 for rs3765524-C). The rs3132468-C allele showed a significant association with lower mRNA level of MICB (P = 0.0267), whereas the rs3765524-C allele did not. These results imply that the MICB molecule may play an important role in the prevention of DSS in dengue infection. CONCLUSIONS: Together with previous association studies, we conclude that rs3132468-C at MICB and rs3765524-C at PLCE1 confer risk of DSS in Southeast Asians.

PLD4 as a novel susceptibility gene for systemic sclerosis in a Japanese population.

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune disease for which multiple susceptibility genes have been reported. Genome-wide association studies have shown that large numbers of susceptibility genes are shared among autoimmune diseases. Recently, our group identified 9 novel susceptibility genes associated with rheumatoid arthritis (RA) in a Japanese population. The aim of this study was to elucidate whether the 18 genes that displayed associations or suggestive associations for RA in our previous study are associated with SSc in Japanese. METHODS: We performed an association study that included 415 patients with SSc and 16,891 control subjects, followed by a replication study that included 315 patients and 21,054 control subjects. The 18 markers reported to display association with RA were analyzed for their associations with SSc in the first study, and 5 markers were further analyzed in the replication study. The inverse variance method was used to evaluate the associations of these markers with SSc in a combined study. RESULTS: In the phospholipase D4 gene (PLD4), rs2841277 displayed a significant association with SSc in Japanese patients (P = 0.00017). We observed that rs2841280 in exon 2 of PLD4 was in strong linkage disequilibrium with rs2841277 and introduced an amino acid alteration. We also observed associations between SSc and rs6932056 in TNFAIP3 and rs2280381 in IRF8 (P = 0.0000095 and P = 0.0030, respectively), both of which displayed associations with SSc in a European population. CONCLUSION: We determined that PLD4 is a novel susceptibility gene for SSc in Japanese, thus confirming the involvement of PLD4 in autoimmunity. Associations between SSc and TNFAIP3 or IRF8 were also detected in our Japanese population. SSc and RA appear to share relatively large proportions of their genetic backgrounds.

Serum biomarker analysis of collagen disease patients with acute-onset diffuse interstitial lung disease.

BACKGROUND: Interstitial lung disease (ILD) is frequently associated with collagen diseases. The prognosis of acute-onset diffuse ILD (AoDILD) occurring in collagen disease patients is very poor. Here, we investigated serum biomarker profiles of AoDILD to find markers predicting outcome in patients with collagen diseases. METHODS: A solid-phase antibody array was used for screening 274 biomarkers in pooled sera from collagen disease patients in the AoDILD state and in the stable state. Biomarkers in individual sera were detected without pooling by bead-based immunoassay. RESULTS: The serum levels of matrix metalloproteinase (MMP)-1, tissue inhibitor of metalloproteinase (TIMP)-1, osteopontin, interleukin (IL)-2 receptor α (IL-2Rα), and IL-1 receptor antagonist were significantly increased in AoDILD, but TIMP-2, MMP-3, and eotaxin 2 levels were decreased. The MMP-3 to MMP-1 ratio was reduced in AoDILD state. This tendency was also observed in RA patients with AoDILD. Moreover, serum IL-6 level was significantly increased in the AoDILD state in patients with acute exacerbation of ILD (AE-ILD). Serum TIMP-1 and IL-2Rα levels were significantly increased in the AoDILD state in patients with drug-induced ILD (DI-ILD), whereas TIMP-2, MMP-3, and eotaxin 2 levels were decreased. The MMP-3 to MMP-1 ratio was reduced in AoDILD state in patients with DI-ILD. The serum TIMP-3, MMP-9, osteopontin, IL-2Rα, MMP-1, and MMP-8 levels were significantly increased in the AoDILD state in patients who subsequently died, whereas TIMP-2 and MMP-3 levels were decreased in those who survived. The MMP-3 to MMP-1 ratio was reduced in AoDILD state in patients who died, but not in those who survived. CONCLUSIONS: Serum biomarker profiles could represent prognosis markers for AoDILD in collagen diseases.

Genetics of ANCA-associated vasculitis in Japan: a role for HLA-DRB1*09:01 haplotype.

The epidemiology of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is considerably different between European and Asian populations. Whereas granulomatosis with polyangiitis is the most common form of AAV in northern European populations, microscopic polyangiitis (MPA) accounts for the majority of AAV in Japan. This difference may at least in part derive from the difference in genetic background. In this review, I focus on our observation on HLA, an obvious candidate gene for immune disorders, and discuss its potential implication. In Japanese AAV, significant association was detected with HLA-DRB1*09:01, the carrier frequency of which was increased in MPA [P=0.0087, odds ratio (OR) 1.90, 95% confidence interval (CI) 1.17-3.08] and in myeloperoxidase (MPO)-ANCA-positive AAV (P=0.0016, OR 2.05, 95% CI 1.31-3.23) when compared with healthy Japanese controls. HLA-DRB1*09:01 is one of the most common HLA-DRB1 alleles in Asians but is rare in Caucasian populations. Interestingly, HLA-DRB1*09:01 has been shown to be associated with multiple autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus, suggesting that either HLA-DRB1*09:01 itself or other genes in tight linkage disequilibrium may play a role in a molecular pathway shared by various autoimmune diseases in Japanese and possibly in other Asian populations.

Sex-specific association of X-linked Toll-like receptor 7 (TLR7) with male systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a multisystem, autoimmune disease that predominantly affects women. Previous findings that duplicated Toll-like receptor 7 (Tlr7) promotes lupus-like disease in male BXSB mice prompted us to evaluate TLR7 in human SLE. By using a candidate gene approach, we identified and replicated association of a TLR7 3'UTR SNP, rs3853839 (G/C), with SLE in 9,274 Eastern Asians (P(combined) = 6.5 x 10(-10)), with a stronger effect in male than female subjects [odds ratio, male vs. female = 2.33 (95% CI = 1.64-3.30) vs. 1.24 (95% CI = 1.14-1.34); P = 4.1 x 10(-4)]. G-allele carriers had increased TLR7 transcripts and more pronounced IFN signature than C-allele carriers; heterozygotes had 2.7-fold higher transcripts of G-allele than C-allele. These data established a functional polymorphism in type I IFN pathway gene TLR7 predisposing to SLE, especially in Chinese and Japanese male subjects.