HLA-DR genotypes in patients with systemic lupus erythematosus in Taiwan.

BACKGROUND: Different human leukocyte antigen (HLA)-DR genotypes have been known to be associated with the risk of development of systemic lupus erythematosus (SLE) in different populations, although Lu et al. have reported previously that no correlation exists between the HLA-DR genotype and disease manifestation in SLE patients in Taiwan. We investigated the effects different HLA-DR genotypes had on SLE incidence in Taiwanese patients as to whether risk alleles were associated with different clinical manifestations, and the effects risk alleles had on the age of disease onset. METHODS: Two hundred thirty-four SLE patients and 346 healthy controls were enrolled. HLA-DR genotyping was performed with the HLA FluoGene DRDQ kit for each subject. Chi-square tests and t tests were performed for statistical analysis. RESULTS: HLA-DR2 was significantly more frequently found in SLE patients than in controls (odds ratio [OR] = 2.05, 95% CI, 1.44-2.92, p < 0.001). Notably, HLA-DR6 appeared to trend toward negative correlation with SLE, whereas HLA-DR8 appeared to trend toward positive correlation. HLA-DR2 patients had an earlier onset of disease as well as a higher prevalence of oral ulcer, avascular necrosis of bone, and renal involvement (lupus nephritis). CONCLUSION: HLA-DR2 was associated with SLE susceptibility in this Taiwanese population as well as lower age of disease onset and more severe clinical manifestations.

The Role of Macrophages in Connective Tissue Disease-Associated Interstitial Lung Disease: Focusing on Molecular Mechanisms and Potential Treatment Strategies.

Connective tissue disease-associated interstitial lung disease (CTD-ILD) is a severe manifestation of CTD that leads to significant morbidity and mortality. Clinically, ILD can occur in diverse CTDs. Pathologically, CTD-ILD is characterized by various histologic patterns, such as nonspecific interstitial pneumonia, organizing pneumonia, and usual interstitial pneumonia. Abnormal immune system responses have traditionally been instrumental in its pathophysiology, and various changes in immune cells have been described, especially in macrophages. This article first briefly overviews the epidemiology, clinical characteristics, impacts, and histopathologic changes associated with CTD-ILD. Next, it summarizes the roles of various signaling pathways in macrophages or products of macrophages in ILD, helped by insights gained from animal models. In the following sections, this review returns to studies of macrophages in CTD-ILD in humans for an overall picture of the current understanding. Finally, we direct attention to potential therapies targeting macrophages in CTD-ILD in investigation or in clinical trials, as well as the future directions regarding macrophages in the context of CTD-ILD. Although the field of macrophages in CTD-ILD is still in its infancy, several lines of evidence suggest the potential of this area.

NLRP3 Gene Polymorphisms in Rheumatoid Arthritis and Primary Sjogren's Syndrome Patients.

Aim: The activation of NLRP3 inflammasome leads to the stimulation of cytokines and is significantly involved in the pathogenesis and progression of autoimmune diseases. The purpose of this study is to examine the associations of NLRP3 gene polymorphisms with rheumatoid arthritis (RA) and primary Sjogren's syndrome (SS) patients. Methods: A total of 239 patients with RA, 285 patients with primary SS, and 170 healthy controls were enrolled. Genomic DNA was extracted from peripheral blood mononuclear cells, and gene polymorphisms were genotyped through the TaqMan assay. Antinuclear antibody (ANA), anti-Ro, and anti-CCP antibodies were detected using immunofluorescence immunoassay. Results: The T allele of rs4612666 CT elevated the susceptibility to RA disease. The RF titer during diagnosis of RA was significantly high in RA patients with the A allele of rs12079994 G/A polymorphism. The titer of anti-CCP during diagnosis of RA was high in the absence of the C allele of rs10754558 C/G polymorphisms in RA patients. Antinuclear antibody and anti-CCP were positively associated with the A allele of rs12079994 G/A polymorphism in primary SS. The C allele of rs4612666 C/T was negatively associated with ANA in primary SS. Conclusions: The results have shown that NLRP3 gene polymorphisms may play a role in the pathogenesis of RA and primary SS.

Methylation of TET2 Promoter Is Associated with Global Hypomethylation and Hypohydroxymethylation in Peripheral Blood Mononuclear Cells of Systemic Lupus Erythematosus Patients.

(1) Background: It is widely accepted that aberrant methylation patterns contribute to the development of systemic lupus erythematosus (SLE). Ten-eleven translocation (TET) methylcytosine dioxygenase is an essential enzyme of which there are three members, TET1, 2, and 3, involved in hydroxymethylation, a newly uncovered mechanism of active DNA methylation. The epigenomes of gene transcription are regulated by 5-hydroxymethylcytocine (5-hmC) and TETs, leading to dysregulation of the immune system in SLE. The purpose of this study was to investigate the global hydroxymethylation status in SLE peripheral blood mononuclear cells (PBMCs) and to explore the role of TETs in changing the patterns of methylation. (2) Methods: We collected PBMCs from 101 SLE patients and 100 healthy donors. TaqMan real-time polymerase chain-reaction assay was performed for the detection of 5-methylcytosine (5-mC), 5-hmC, and TET2 mRNA expression and single-nucleotide polymorphism genotyping. The methylation rates in different CpG sites of TET2 promoters were examined using next-generation sequencing-based deep bisulfite sequencing. Putative transcription factors were investigated using the UCSC Genome Browser on the Human Dec. 2013 (GRCh38/hg38) Assembly. (3) Results: 5-mC and 5-hmC were both decreased in SLE. The mRNA expression level of TET2 was notably high and found to be correlated with the levels of immunologic biomarkers that are indicative of SLE disease activity. The analysis of methylation rates in the TET2 promoter revealed that SLE patients had significantly higher and lower rates of methylation in TET2 105146072-154 and TET2 105146218-331, respectively. (4) Conclusions: TET2 may play an important role in 5-mC/5-hmC dynamics in the PBMCs of SLE patients. The epigenetic modification of TET2 promoters could contribute to the pathogenesis of SLE and the intensity of the immunologic reaction.

Genetic and epigenetic alterations of cyclic AMP response element modulator in rheumatoid arthritis.

BACKGROUND: Genetic and epigenetic factors are strongly associated with the autoimmune disease rheumatoid arthritis (RA). Cyclic AMP response element modulator (CREM), a gene related to immune system regulation, has been implicated in various immune-mediated inflammatory processes, although it remains unknown whether CREM is involved in RA. METHODS: This study enrolled 278 RA patients and 262 controls. Three variants [rs12765063, rs17499247, rs1213386] were identified through linkage disequilibrium and expression quantitative trait locus analysis, and CREM transcript abundance was determined by quantitative real-time polymerase chain reaction. The identified variants were genotyped using the TaqMan Allelic Discrimination assay, and CREM promoter methylation was assessed by bisulphite sequencing. Differences between groups and correlations between variables were assessed with Student's t-tests and Pearson's correlation coefficients. Associations between phenotypes and genotypes were evaluated with logistic regression. RESULTS: Rheumatoid arthritis patients exhibited increased CREM expression (p < .0001), which was decreased by methotrexate (p = .0223) and biologics (p = .0001), but could not be attributed to CREM variants. Interestingly, rs17499247 displayed a significant association with serositis (p = .0377), and rs1213386 increased the risk of lymphadenopathy (p = .0398). Furthermore, seven CpG sites showed decreased methylation in RA (p = .0477~ p < .0001). CONCLUSIONS: Collectively, our results indicate that CREM hypomethylation and CREM upregulation occur in RA and that CREM variants are involved in the development of serositis and lymphadenopathy in RA. This study highlights the novel roles of CREM in RA pathophysiology.

Genetic Variants in Transcription Factor Binding Sites in Humans: Triggered by Natural Selection and Triggers of Diseases.

Variants of transcription factor binding sites (TFBSs) constitute an important part of the human genome. Current evidence demonstrates close links between nucleotides within TFBSs and gene expression. There are multiple pathways through which genomic sequences located in TFBSs regulate gene expression, and recent genome-wide association studies have shown the biological significance of TFBS variation in human phenotypes. However, numerous challenges remain in the study of TFBS polymorphisms. This article aims to cover the current state of understanding as regards the genomic features of TFBSs and TFBS variants; the mechanisms through which TFBS variants regulate gene expression; the approaches to studying the effects of nucleotide changes that create or disrupt TFBSs; the challenges faced in studies of TFBS sequence variations; the effects of natural selection on collections of TFBSs; in addition to the insights gained from the study of TFBS alleles related to gout, its associated comorbidities (increased body mass index, chronic kidney disease, diabetes, dyslipidemia, coronary artery disease, ischemic heart disease, hypertension, hyperuricemia, osteoporosis, and prostate cancer), and the treatment responses of patients.

Association of F11R polymorphisms and gene expression with primary Sjögren's syndrome patients.

AIMS: F11R gene encodes junctional adhesion molecule-A protein (JAM-A), which is expressed in various types of cells and is involved in leukocyte extravasation during inflammation. Sjögren's syndrome (SS) is a chronic systemic inflammatory disease that involves lymphocytes invasion of exocrine glands. F11R has been studied in autoimmune diseases, but any association between F11R and SS has not yet been investigated. Therefore, experiments were undertaken to examine the relationships among F11R gene polymorphism, messenger RNA (mRNA) expression and SS patients. METHODS: Three hundred and twenty-nine patients with SS, and 223 healthy controls were enrolled in their recruitment from the Kaohsiung Medical University Hospital. Genomic DNA was extracted from peripheral blood mononuclear cells and gene polymorphisms were genotyped by TaqMan real-time polymerase chain reaction (PCR). F11R mRNA expression was quantitated by quantitative real-time PCR with TaqMan Gene Expression Assay. RESULTS: Our study showed the genotype -688A/C (rs6695707) was not found in relation to SS patients. The odds ratio of -436A/G (rs12567886) genotype was notably associated with less susceptibility of SS in human leukocyte antigen (HLA)-DR2 negative and HLA-DR3 negative individuals. F11R mRNA expression was lower in SS patients than in the cells of healthy controls. CONCLUSION: The result indicated that G allele of -436A/G genotype has the potential protective effect against SS disease condition. F11R mRNA was expressed significantly lower in SS patients.

Cell lineage-specific methylome and genome alterations in gout.

In this study, we examined data from 69 gout patients and 1,455 non-gout controls using a MethylationEPIC BeadChip assay and Illumina HiSeq platform to identify lineage-specific epigenetic alterations and associated genetic factors that contributed to gouty inflammation. Cell lineage-specific differentially methylated sites were identified using CellDMC after adjusting for sex, age, alcohol drinking, smoking status, and smoking history (total pack-years). Different cell lineages displayed distinct differential methylation. Ingenuity Pathway Analysis and NetworkAnalyst indicated that many differential methylated sites were associated with interleukin-1ß expression in monocytes. On the UCSC Genome Browser and WashU Epigenome Browser, metabolic trait, cis-methylation quantitative trait loci, genetic, and functional annotation analyses identified nine methylation loci located in interleukin-1ß-regulating genes (PRKCZ, CIDEC, VDAC1, CPT1A, BIRC2, BRCA1, STK11, and NLRP12) that were associated specifically with gouty inflammation. All nine sites mapped to active regulatory elements in monocytes. MoLoTool and ReMap analyses indicated that the nine methylation loci overlapped with binding sites of several transcription factors that regulated interleukin-1ß production and gouty inflammation. Decreases in PRKCZ and STK11 methylation were also associated with higher numbers of first-degree relatives who also had gout. The gouty-inflammation specific methylome and genome alterations could potentially aid in the identification of novel therapeutic targets.

Systemic Investigation of Promoter-wide Methylome and Genome Variations in Gout.

Current knowledge of gout centers on hyperuricemia. Relatively little is known regarding the pathogenesis of gouty inflammation. To investigate the epigenetic background of gouty inflammation independent of hyperuricemia and its relationship to genetics, 69 gout patients and 1455 non-gout controls were included. Promoter-wide methylation was profiled with EPIC array. Whole-genome sequencing data were included for genetic and methylation quantitative trait loci (meQTL) analyses and causal inference tests. Identified loci were subjected to co-methylation analysis and functional localization with DNase hypersensitivity and histone marks analysis. An expression database was queried to clarify biologic functions of identified loci. A transcription factor dataset was integrated to identify transcription factors coordinating respective expression. In total, seven CpG loci involved in interleukin-1ß production survived genetic/meQTL analyses, or causal inference tests. None had a significant relationship with various metabolic traits. Additional analysis suggested gouty inflammation, instead of hyperuricemia, provides the link between these CpG sites and gout. Six (PGGT1B, INSIG1, ANGPTL2, JNK1, UBAP1, and RAPTOR) were novel genes in the field of gout. One (CNTN5) was previously associated with gouty inflammation. Transcription factor mapping identified several potential transcription factors implicated in the link between differential methylation, interleukin-1ß production, and gouty inflammation. In conclusion, this study revealed several novel genes specific to gouty inflammation and provided enhanced insight into the biological basis of gouty inflammation.

Rapid establishment of a COVID-19 biobank in NHRI by National Biobank Consortium of Taiwan.

By the request of the Minister of Health and Welfare, NHRI Biobank was assigned to establish a COVID-19 biobank in early Feb, 2020 to collect COVID-19 patients' blood samples for Taiwan researchers and industries in an emergent way. It was set up in less than 3 weeks and quickly opened for application. By August 5, 2020, this COVID-19 biobank has collected 165 blood samples of 110 patients from more than 10 hospitals across north, middle and south part of Taiwan, including both COVID-19 (+) and (-) pneumonia patients. This biobank can provide applicants with biosamples, such as serum, DNA and RNA, and also the clinical and genomic data, so as to accelerate the COVID-19 treatment and prevention research in Taiwan. This COID-19 biobank already received 15 applications. It has become the most important research resource for the COVID-19 pandemic in Taiwan, including new screening reagents, disease mechanism, the variable human responses and epidemic preventions. Since it is publicly available for both academic and industrial applicants.

Dual Role of Chondrocytes in Rheumatoid Arthritis: The Chicken and the Egg.

Rheumatoid arthritis (RA) is one of the inflammatory joint diseases that display features of articular cartilage destruction. The underlying disturbance results from immune dysregulation that directly and indirectly influence chondrocyte physiology. In the last years, significant evidence inferred from studies in vitro and in the animal model offered a more holistic vision of chondrocytes in RA. Chondrocytes, despite being one of injured cells in RA, also undergo molecular alterations to actively participate in inflammation and matrix destruction in the human rheumatoid joint. This review covers current knowledge about the specific cellular and biochemical mechanisms that account for the chondrocyte signatures of RA and its potential applications for diagnosis and prognosis in RA.

Differential Expression Profiles of the Transcriptome and miRNA Interactome in Synovial Fibroblasts of Rheumatoid Arthritis Revealed by Next Generation Sequencing.

Using next-generation sequencing to decipher the molecular mechanisms underlying aberrant rheumatoid arthritis synovial fibroblasts (RASF) activation, we performed transcriptome-wide RNA-seq and small RNA-seq on synovial fibroblasts from rheumatoid arthritis (RA) subject and normal donor. Differential expression of mRNA and miRNA was integrated with interaction analysis, functional annotation, regulatory network mapping and experimentally verified miRNA-target interaction data, further validated with microarray expression profiles. In this study, 3049 upregulated mRNA and 3552 downregulated mRNA, together with 50 upregulated miRNA and 35 downregulated miRNA in RASF were identified. Interaction analysis highlighted contribution of miRNA to altered transcriptome. Functional annotation revealed metabolic deregulation and oncogenic signatures of RASF. Regulatory network mapping identified downregulated FOXO1 as master transcription factor resulting in altered transcriptome of RASF. Differential expression in three miRNA and corresponding targets (hsa-miR-31-5p:WASF3, hsa-miR-132-3p:RB1, hsa-miR-29c-3p:COL1A1) were also validated. The interactions of these three miRNA-target genes were experimentally validated with past literature. Our transcriptomic and miRNA interactomic investigation identified gene signatures associated with RASF and revealed the involvement of transcription factors and miRNA in an altered transcriptome. These findings help facilitate our understanding of RA with the hope of serving as a springboard for further discoveries relating to the disease.

Next-Generation Sequencing Profiles of the Methylome and Transcriptome in Peripheral Blood Mononuclear Cells of Rheumatoid Arthritis.

Using next-generation sequencing to decipher methylome and transcriptome and underlying molecular mechanisms contributing to rheumatoid arthritis (RA) for improving future therapies, we performed methyl-seq and RNA-seq on peripheral blood mononuclear cells (PBMCs) from RA subjects and normal donors. Principal component analysis and hierarchical clustering revealed distinct methylation signatures in RA with methylation aberrations noted across chromosomes. Methylation alterations varied with CpG features and genic characteristics. Typically, CpG islands and CpG shores were hypermethylated and displayed the greatest methylation variance. Promoters were hypermethylated and enhancers/gene bodies were hypomethylated, with methylation variance associated with expression variance. RA genetically associated genes preferentially displayed differential methylation and differential expression or interacted with differentially methylated and differentially expressed genes. These differentially methylated and differentially expressed genes were enriched with several signaling pathways and disease categories. 10 genes (CD86, RAB20, XAF1, FOLR3, LTBR, KCNH8, DOK7, PDGFA, PITPNM2, CELSR1) with concomitantly differential methylation in enhancers/promoters/gene bodies and differential expression in B cells were validated. This integrated analysis of methylome and transcriptome identified novel epigenetic signatures associated with RA and highlighted the interaction between genetics and epigenetics in RA. These findings help our understanding of the pathogenesis of RA and advance epigenetic studies in regards to the disease.

GADD45a and GADD45b Genes in Rheumatoid Arthritis and Systemic Lupus Erythematosus Patients.

BACKGROUND: GADD45 genes are stress sensors in response to cellular stress response, activated signal pathways leading to the stimulation of inflammatory cytokines. This study is to examine the associations of GADD45a and GADD45b genes with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients. METHODS: 230 patients of RA, 140 patients of SLE, and 191 healthy controls were enrolled. Genomic DNA was extracted from peripheral blood mononuclear cells and gene polymorphisms were genotyped by TaqMan assay. RNA expression was quantitated with real-time polymerase chain reaction. RESULTS: The RNA expression of the GADD45b gene was significantly lower in RA patients than the control cases (p = 0.03). The odds ratio of GADD45a genotype -589 CC (rs581000) was significantly low (OR = 0.36, 95% CI, 0.15-0.87) in DR4-negative RA patients. The odds ratio of GADD45b genotype -712CT (rs3795024) in DR4-negative RA patients was 0.41 (95% CI, 0.18-0.95). In clinical manifestation, the odds ratio of GADD45b -712CT genotype with anti-RNP antibody was 4.14 (95% CI, 1.10-15.63) in SLE patients. GADD45a genotype -589GG+GC was associated with rheumatoid factor (RF) in SLE patients. CONCLUSIONS: Genotypes GADD45a -589CC and GADD45b -712CT were shown to be less susceptible to RA and related to the disease state in SLE patients.

Genetic and epigenetic alteration of the programmed cell death 1 in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease where both genetics and epigenetics are contributing factors. In order to discover genetic and epigenetic associations with RA and its phenotypes, we analysed RNA expression, DNA variations and DNA methylation of programmed cell death 1 (PDCD1) in a cohort of RA patients and healthy controls. METHODS: RA patients (n = 206) and healthy controls (n = 234) were included for analysis of PDCD1 expression, PDCD1 polymorphisms and PDCD1 methylation. Differences in continuous variables between groups were compared by applying t tests. Associations between phenotypes and genotypes were evaluated with contingency tables. Sensitivity analyses were conducted to confirm the robustness of results, considering potential confounding factors and different treatment response definitions. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated. RESULTS: Higher expression of PDCD1 was found in RA compared to controls (P < 0.001), with similar PDCD1 polymorphisms in RA and controls. rs36084323 decreased inadequate response to conventional synthetic disease-modifying antirheumatic drugs (OR = 0.37, 95% CI = 0.19-0.72, P = 0.003), and rs41386349 increased rheumatoid factor seropositivity (OR = 11.89, 95% CI = 1.57-89.87, P = 0.003). Sensitivity analysis adjusting for further potential confounders and using different treatment response definition indicated similar results. Additionally, DNA methylation change at regulatory region of PDCD1 was detected in RA (P = 0.036). CONCLUSION: Altogether, this was the first study to suggest genetic and epigenetic changes of PDCD1 in RA subsets and RA. Independent prospective cohorts are awaited to address the implications of these genetic and epigenetic changes in disease pathogenesis and phenotypes of RA.

Next-generation sequencing profiling of mitochondrial genomes in gout.

BACKGROUND: Accumulating evidence implicates mitochondrial DNA (mtDNA) alleles, which are independent of the nuclear genome, in disease, especially in human metabolic diseases. However, this area of investigation has lagged behind in researching the nuclear alleles in complex traits, for example, in gout. METHODS: Next-generation sequencing was utilized to investigate the relationship between mtDNA alleles and phenotypic variations in 52 male patients with gout and 104 age-matched male non-gout controls from the Taiwan Biobank whole-genome sequencing samples. Differences from a reference sequence (GRCh38) were identified. The sequence kernel association test (SKAT) was applied to identify gout-associated alleles in mitochondrial genes. The tools Polymorphism Phenotyping, Sorting Intolerant From Tolerant (SIFT), Predict the pathology of Mutations (PMUT), Human Mitochondrial Genome Database (mtDB), Multiple Alignment using Fast Fourier Transform (MAFFT), and Mammalian Mitochondrial tRNA Genes (Mamit-tRNA) were used to evaluate pathogenicity of alleles. Validation of selected alleles by quantitative polymerase chain reaction of single nucleotide polymorphisms (qPCR SNPs) was also performed. RESULTS: We identified 456 alleles in patients with gout and 640 alleles in non-gout controls with 274 alleles shared by both. Mitochondrial genes were associated with gout, with MT-CO3, MT-TA, MT-TC, and MT-TT containing potentially pathogenic gout-associated alleles and displaying evidence of gene-gene interactions. All heteroplasmy levels of potentially pathogenic alleles exceeded metabolic thresholds for pathogenicity. Validation assays confirmed the next-generation sequencing results of selected alleles. Among them, potentially pathogenic MT-CO3 alleles correlated with high-density lipoprotein (HDL) levels (P = 0.034). CONCLUSION: This study provided two scientific insights. First, this was the most extensive mitochondrial genomic profiling associated with gout. Second, our results supported the roles of mitochondria in gout and HDL, and this comprehensive analysis framework can be applied to other diseases in which mitochondrial dysfunction has been implicated.

ABCG2 contributes to the development of gout and hyperuricemia in a genome-wide association study.

Although many genome-wide association studies (GWASs) of hyperuricemia or gout have been reported, the related genetic factors and the mechanisms from hyperuricemia to gouty attack remain unclear. This study aimed to identify genetic factors and pathogenesis of gout from hyperuricemia by genome-wide association study (GWAS). 747 gout patients, 747 hyperuricemia and 2071 age-matched controls were recruited and analyzed with Affymetrix 650 K chip to find the related genetic variants. The functions of the related genes were investigated in an endothelial cell (EC) with urate crystal stimulation. The GWAS results showed 36 SNPs to be strongly associated with gout compared to controls (all p-values < 10-7). Whereas the rs2231142 in ABCG2 gene had significant associations between gout and controls, between gout and hyperuricemia, and between hyperuricemia and controls (all p-values < 10-7), and the ORs were 4.34, 3.37 and 2.15 (all p-values < 0.001) after adjustment of potential confounders, respectively. The cell model showed significantly higher IL-8 release from EC combined with ABCG2 knockdown. We concluded that ABCG2 gene contributed to hyperuricemia but also gout, and that it was involved in the inflammation dysregulation via augmented IL-8 release in EC.

Sex differential association of dermatomyositis with Sjögren syndrome.

BACKGROUND: Although dermatomyositis and Sjögren syndrome share serologic autoantibodies and genetic polymorphisms, population data about the incidence of Sjögren syndrome in patients with dermatomyositis is unavailable. We performed a nationwide cohort study to explore the potential relation between dermatomyositis and Sjögren syndrome and, if an association exists, to elucidate whether it varies by sex. METHODS: We identified all patients with newly diagnosed dermatomyositis from the Registry of Catastrophic Illness Database in Taiwan between Jan. 1, 1998, and Dec. 31, 2011. Each patient was matched to, at most, 5 control patients from the National Health Insurance Research Database by age, sex and entry date. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) of Sjögren syndrome after adjusting for age, sex, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. RESULTS: A total of 1602 patients with dermatomyositis and 7981 control patients were enrolled in the study. There was a positive association of having Sjögren syndrome among patients with dermatomyositis after adjusting for age, sex, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis (HR 2.67, 95% CI 2.01-3.54). The association was more pronounced in the male cohort (HR 2.69, 95% CI 1.19-6.09). INTERPRETATION: We found a sex differential association of Sjögren syndrome among patients with dermatomyositis independent of age and concomitant autoimmune disease. Further studies are required to determine the clinical importance of this association for both outcomes and therapeutic options.

Increased Incidence of Amyotrophic Lateral Sclerosis in Polymyositis: A Nationwide Cohort Study.

OBJECTIVE: Past studies have shown common pathologic characteristics and shared immunologic features between polymyositis (PM) and amyotrophic lateral sclerosis (ALS). To explore the potential relationship between the 2 diseases, we performed a nationwide cohort study. METHODS: We identified all newly diagnosed patients with PM from Taiwan's Registry of Catastrophic Illness Database between January 1, 1998 and December 31, 2011. Each PM patient was matched to ≤5 control patients from the National Health Insurance Research Database by sex, age, and entry date. Cumulative incidence of ALS was calculated by the Kaplan-Meier method and compared using the log rank test. Cox hazard regression was used to calculate the hazard ratio of ALS. RESULTS: A total of 1,778 PM patients and 8,124 control patients were enrolled. PM patients had a higher cumulative incidence of ALS (P < 0.001). There was a positive correlation in being diagnosed with ALS in patients previously diagnosed with PM when stratified by sex. Consistent trends were conserved across different age strata. The strength of this association remained statistically significant after adjusting for sex, age, and concomitant autoimmune diseases (hazard ratio 25.72 [95% confidence interval 2.95-224.58]; P = 0.003). CONCLUSION: This study demonstrates that a diagnosis of PM increased the likelihood of a subsequent ALS diagnosis, independent of sex, age, and concomitant autoimmune diseases. Future studies are warranted to clarify the underlying biologic mechanisms and to translate them into clinical therapeutic options.