Genotyping of immune-related genetic variants identifies TYK2 as a novel associated locus for idiopathic inflammatory myopathies

TYK2: an emerging therapeutic target in rheumatic disease

Tyrosine kinase 2 (TYK2) is a member of the JAK kinase family of intracellular signalling molecules. By participating in signalling pathways downstream of type I interferons, IL-12, IL-23 and IL-10, TYK2 elicits a distinct set of immune events to JAK1, JAK2 and JAK3. TYK2 polymorphisms have been associated with susceptibility to various rheumatic diseases including systemic lupus erythematosus and dermatomyositis. In vitro and animal studies substantiate these findings, highlighting a role for TYK2 in diseases currently managed by antagonists of cytokines that signal through TYK2. Various inhibitors of TYK2 have now been studied in human disease, and one of these inhibitors, deucravacitinib, has now been approved for the treatment of psoriasis. Phase II trials of deucravacitinib have also reported positive results in the treatment of psoriatic arthritis and systemic lupus erythematosus, with a preliminary safety profile that seems to differ from that of the JAK1, JAK2 and JAK3 inhibitors. Two other inhibitors of TYK2, brepocitinib and ropsacitinib, are also in earlier stages of clinical trials. Overall, TYK2 inhibitors hold promise for the treatment of a distinct spectrum of autoimmune diseases and could potentially have a safety profile that differs from other JAK inhibitors.

Juvenile idiopathic inflammatory myositis: an update on pathophysiology and clinical care

The childhood-onset or juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogenous group of rare and serious autoimmune diseases of children and young people that predominantly affect the muscles and skin but can also involve other organs, including the lungs, gut, joints, heart and central nervous system. Different myositis-specific autoantibodies have been identified that are associated with different muscle biopsy features, as well as with different clinical characteristics, prognoses and treatment responses. Thus, myositis-specific autoantibodies can be used to subset JIIMs into sub-phenotypes; some of these sub-phenotypes parallel disease seen in adults, whereas others are distinct from adult-onset idiopathic inflammatory myopathies. Although treatments and management have much improved over the past decade, evidence is still lacking for many of the current treatments and few validated prognostic biomarkers are available with which to predict response to treatment, comorbidities (such as calcinosis) or outcome. Emerging data on the pathogenesis of the JIIMs are leading to proposals for new trials and tools for monitoring disease.

Proteomics Analysis of Plasma-Derived Exosomes Unveils the Aberrant Complement and Coagulation Cascades in Dermatomyositis/Polymyositis

Dermatomyositis and polymyositis (DM/PM) are systemic autoimmune diseases characterized by proximal muscle weakness. The underlying pathogenetic mechanism of this disease remains under-researched. Here, using proteomics analysis, a great overlap of differentially expressed plasma exosomal proteins involved in the complement and coagulation cascade pathway, including FGA, FGB, FGG, C1QB, C1QC, and VWF, was identified in DM/PM patients versus healthy controls. Correlation analysis showed that the expression levels of complement-associated proteins (C1QB and C1QC) correlated positively with CRP, ESR, and platelet count. ROC curve analysis demonstrated that complement and coagulation cascade-associated proteins could be strong predictors for DM/PM. In addition, we also identified several other proteins that were differentially expressed in DM and PM. The selected candidate proteins were further validated by parallel reaction monitoring (PRM) and enzyme-linked immunosorbent assay (ELISA). Together, our findings indicate that these exosome-derived proteins might participate in microvascular damage in DM/PM through the activation of the complement and coagulation cascade pathway and function as biomarkers for the clinical diagnosis of DM/PM.

JAK inhibitors: a potential treatment for JDM in the context of the role of interferon-driven pathology

Juvenile Idiopathic Inflammatory Myopathies (IIM) are a group of rare diseases that are heterogeneous in terms of pathology that can include proximal muscle weakness, associated skin changes and systemic involvement. Despite options for treatment, many patients continue to suffer resistant disease and lasting side-effects. Advances in the understanding of the immunopathology and genetics underlying IIM may specify new therapeutic targets, particularly where conventional treatment has not achieved a clinical response. An upregulated type I interferon signature is strongly associated with disease and could be a prime target for developing more specific therapeutics. There are multiple components of the IFN pathway that could be targeted for blockade therapy.Downstream of the cytokine receptor complexes are the Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway, which consists of JAK1-3, TYK2, and STAT1-6. Therapeutic inhibitors have been developed to target components of this pathway. Promising results have been observed in case studies reporting the use of the JAK inhibitors, Baricitinib, Tofacitinib and Ruxolitinib in the treatment of refractory Juvenile Dermatomyositis (JDM). There is still the question of safety and efficacy for the use of JAK inhibitors in JDM that need to be addressed by clinical trials. Here we review the future for the use of JAK inhibitors as a treatment for JDM.

Genetics of idiopathic inflammatory myopathies: insights into disease pathogenesis

To review the advances that have been made in our understanding of the genetics of idiopathic inflammatory myopathies (IIM) in the past 2 years, with a particular focus on dermatomyositis and polymyositis.

Targeted capture sequencing identifies novel genetic variations in Chinese patients with idiopathic inflammatory myopathies

OBJECTIVES

Previous association studies have identified genetic variants in the human leukocyte antigen (HLA) complex as substantial risk factors for idiopathic inflammatory myopathies (IIMs). However, a great number of genes are located in the HLA region, and thus fine mapping is quite necessary.

METHODS

Targeted capture sequencing were performed on the whole HLA region in 42 IIM patients and 24 healthy controls. A microarray analysis was applied to analyze gene expression profiles in additional 20 newly diagnosed IIM and five healthy controls.

RESULTS

The HLA region was confirmed to be associated with IIMs in Chinese patients. By gene expression profiling and pathway analysis, several genes were identified as candidates for IIM risk factors, including HLA-A, HLA-B, HLA-DRB5, HLA-DRB1, HLA-DQA1, HLA-DQB1 and HLA-DQB2. Interestingly, p.Y107V of the HLA-DRB1 was predicted to be a potential causal non-synonymous variation for IIMs that may affect the antigen-binding groove of the HLA-II molecule.

CONCLUSIONS

Our data have revealed novel genetic variations in the HLA region of IIM patients and provide new insight into the pathogenesis and diagnosis of IIMs.

Phase 2 Trial of Selective Tyrosine Kinase 2 Inhibition in Psoriasis

BACKGROUND

Tyrosine kinase 2 (TYK2) signaling pathways, which mediate cytokine signaling, are implicated in the pathophysiology of psoriasis. Selective inhibitors of TYK2 may be effective in treating psoriasis.

METHODS

We conducted a phase 2, double-blind trial of a TYK2 inhibitor, BMS-986165, in adults with moderate-to-severe psoriasis, excluding patients with a previous lack of response to agents targeting cytokine signaling through the same tyrosine kinase pathway. Patients were randomly assigned to receive the drug orally at a dose of 3 mg every other day, 3 mg daily, 3 mg twice daily, 6 mg twice daily, or 12 mg daily or to receive placebo. The primary end point was a 75% or greater reduction from baseline in the Psoriasis Area and Severity Index (PASI) score at week 12 (higher scores indicate greater severity of psoriasis).

RESULTS

A total of 267 patients received at least one dose in an intervention group of the trial. At week 12, the percentage of patients with a 75% or greater reduction in the PASI score was 7% (3 of 45 patients) with placebo, 9% (4 of 44 patients) with 3 mg of BMS-986165 every other day (P=0.49 vs. placebo), 39% (17 of 44 patients) with 3 mg daily (P<0.001 vs. placebo), 69% (31 of 45 patients) with 3 mg twice daily (P<0.001 vs. placebo), 67% (30 of 45 patients) with 6 mg twice daily (P<0.001 vs. placebo), and 75% (33 of 44 patients) with 12 mg daily (P<0.001 vs. placebo). There were three serious adverse events in patients receiving the active drug, as well as one case of malignant melanoma 96 days after the start of treatment.

CONCLUSIONS

Selective inhibition of TYK2 with the oral agent BMS-986165 at doses of 3 mg daily and higher resulted in greater clearing of psoriasis than did placebo over a period of 12 weeks. Larger and longer-duration trials of this drug are required to determine its safety and durability of effect in patients with psoriasis. (Funded by Bristol-Myers Squibb; ClinicalTrials.gov number, NCT02931838 .).

Association between the BANK1 rs3733197 polymorphism and polymyositis/dermatomyositis in a Chinese Han population

The aim of our study was to investigate the association between single nucleotide polymorphisms (SNPs) in the BANK1 gene and polymyositis/dermatomyositis (PM/DM) in a Chinese Han population. In total, 363 PM patients, 654 DM patients, and 1280 healthy controls were recruited and genotyped using the Sequenom MassArray system. A significant allele association was observed in rs3733197 among the PM/DM patients (OR 0.81, 95%CI 0.70-0.94, Pc = 1.83 × 10^-2). Notably, rs3733197 was associated with DM and PM/DM patients with ILD involvement (Pc = 0.026; Pc = 6.0 × 10^-3, respectively). However, no statistically significant difference was observed in the allele or genotype frequencies of three SNPs (rs4522865, rs17266594, and rs10516487) among the DM, PM, and PM/DM patients and healthy controls (all Pc > 0.05). This study was the first to demonstrate that a BANK1 gene SNP (rs3733197) could confer genetic predisposition in PM/DM patients and PM/DM patients with ILD in a Chinese Han population.

Lung Involvements in Rheumatic Diseases: Update on the Epidemiology, Pathogenesis, Clinical Features, and Treatment

Lung illness encountered in patients with rheumatic diseases bears clinical significance in terms of increased morbidity and mortality as well as potential challenges placed on patient care. Although our understanding of natural history of this important illness is still limited, epidemiologic knowledge has been accumulated during the past decade to provide useful information on the risk factors and prognosis of lung involvements in rheumatic diseases. Moreover, the pathogenesis particularly in the context of genetics has been greatly updated for both the underlying rheumatic disease and associated lung involvement. This review will focus on the current update on the epidemiologic and genetics features and treatment options of the lung involvements associated with four major rheumatic diseases (rheumatoid arthritis, systemic sclerosis, myositis, and systemic lupus erythematosus), with more attention to a specific form of involvement or interstitial lung disease.

Splicing variant of WDFY4 augments MDA5 signalling and the risk of clinically amyopathic dermatomyositis

OBJECTIVES

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases in which both genetic and environmental factors play important roles. To identify genetic factors of IIM including polymyositis, dermatomyositis (DM) and clinically amyopathic DM (CADM), we performed the first genome-wide association study for IIM in an Asian population.

METHODS

We genotyped and tested 496 819 single nucleotide polymorphism for association using 576 patients with IIM and 6270 control subjects. We also examined the causal mechanism of disease-associated variants by in silico analyses using publicly available data sets as well as by in in vitro analyses using reporter assays and apoptosis assays.

RESULTS

We identified a variant in WDFY4 that was significantly associated with CADM (rs7919656; OR=3.87; P=1.5×10^-8). This variant had a cis-splicing quantitative trait locus (QTL) effect for a truncated WDFY4isoform (tr-WDFY4), with higher expression in the risk allele. Transexpression QTL analysis of this variant showed a positive correlation with the expression of NF-κB associated genes. Furthermore, we demonstrated that both WDFY4 and tr-WDFY4 interacted with pattern recognition receptors such as TLR3, TLR4, TLR9 and MDA5 and augmented the NF-κB activation by these receptors. WDFY4 isoforms also enhanced MDA5-induced apoptosis to a greater extent in the tr-WDFY4-transfected cells.

CONCLUSIONS

As CADM is characterised by the appearance of anti-MDA5 autoantibodies and severe lung inflammation, the WDFY4 variant may play a critical role in the pathogenesis of CADM.

Single nucleotide polymorphisms in the ETS1 gene are associated with idiopathic inflammatory myopathies in a northern Chinese Han population

Single-nucleotide polymorphisms (SNPs) in the ETS1 gene are associated with several auto-inflammatory diseases. In this study, we determined whether ETS1 gene polymorphisms confer susceptibility to idiopathic inflammatory myopathies (IIMs) in a northern Chinese Han population. DNA samples were collected from 1017 IIM patients: 363 PM cases and 654 DM cases. The results were compared with those of 1280 healthy controls. Five SNPs in the ETS1 region (rs7117932, rs6590330, rs4937362, rs10893845 and rs1128334) were assessed and genotyped using the Sequenom platform. Our data indicated that the rs7117932 alleles and genotypes are associated with DM and IIMs (P_c = 6.0 × 10⁻³ and P_c = 0.029; P_c = 0.013 and P_c = 0.019, respectively). We found a significantly greater percentage of DM and IIM patients with an A allele of rs6590330 than that in the control population (P_c = 0.033 and P_c = 0.013). Additionally, the rs6590330 genotype was associated with IIMs (P_c = 0.020). The percentages of rs7117932 and rs6590330 SNPs were significantly greater in DM and IIM patients with interstitial lung disease (ILD) (all P_c < 0.05). This is the first study to reveal that ETS1 polymorphisms are associated with IIMs alone and IIMs with ILD in a northern Chinese Han population.

GLIS3 and TYK2 Single Nucleotide Polymorphisms Are Not Associated with Dermatomyositis/Polymyositis in Chinese Han Population

AIM

Racial differences and genetic overlap have been shown to be responsible for the difference in susceptibility to dermatomyositis (DM)/polymyositis (PM) in a variety of populations. Single nucleotide polymorphisms (SNPs) in the GLI-similar 3 (GLIS3) and tyrosine kinase 2 (TYK2) genes have been associated with various autoimmune diseases. The aim of this study was to investigate whether SNPs in GLIS3 (rs7020673, rs10758593, and rs10814916) and TYK2 (rs280519, rs2304256, rs17000730, and rs280501) were associated with an increase in susceptibility to DM/PM in a Chinese Han population.

MATERIALS AND METHODS

SNPs in GLIS3 and TYK2 were analyzed in a cohort of 1017 patients with DM/PM and 1280 healthy controls using a Sequenom MassArray system. Association analyses were performed using the PLINK v1.07 software.

RESULTS

In our study, the GLIS3 polymorphisms rs7020673 and rs10758593 were initially found to be predisposing risk factors for PM and PM with interstitial lung disease (p < 0.05). Both rs7020673 and rs10758593 were associated with PM in both additive and dominant models (p < 0.05); however, these observed associations were not apparent after Bonferroni correction. Other SNPs examined in our study were not associated with susceptibility to DM/PM.

CONCLUSION

GLIS3 and TYK2 polymorphisms are not associated with DM/PM in the Chinese Han population. As associations of SNPs in these genes in patients with DM/PM have been previously reported in other populations, we may conclude that the lack of association in our study may be the result of differences in genetic background. Further studies in other populations are needed to confirm our findings.

Positive association of genetic variations in the phospholipase C-like 1 gene with dermatomyositis in Chinese Han

Idiopathic inflammatory myopathies (IIMs) are autoimmune diseases with an underlying yet undefined genetic component. Recently, phospholipase C-like 1 (PLCL1) has been identified as a potential genetic susceptibility locus for dermatomyositis (DM) in patients of European ancestry. Here, association between PLCL1 polymorphisms and IIMs was investigated in Chinese Han. Genomic DNA was isolated from blood samples (2 mL) collected from Chinese Han (≥18 years) with polymyositis (PM, n = 286) or dermatomyositis (DM, n = 535) and ethnically matched controls (n = 968). Patients and controls were genotyped for five SNPs (rs938929, rs1518364, rs6738825, rs2117339, and rs7572733) previously associated with DM, with the Sequenom MassARRAY system. SNPs rs6738825 and rs7572733 were found to be associated with the development of DM in Chinese Han (P c = 0.015; P c = 0.025, respectively) as well as the risk A allele of rs938929 and T allele of rs1518364 (P c = 0.030; P c = 0.029). None of the five SNPs were associated with PM (all P c > 0.05). The frequency of the two haplotypes of these five SNPs was also significantly different between DM patients and healthy controls. In addition, conditional analysis with rs6738825 revealed that these SNPs were not independent factors contributing to DM. Finally, a novel association between rs6738825 and rs7572733 and DM with complicating interstitial lung disease was observed (ILD; P c = 0.040; P c = 0.030, respectively). A positive association between PLCL1 polymorphisms and DM patients and DM patients with ILD was observed, indicating that PLCL1 might be the susceptibility gene for DM patients in Chinese Han.

Targeting cytokine signaling in autoimmunity: back to the future and beyond

Cytokines represent structurally diverse soluble factors with critical roles in normal immune function and the pathogenesis of autoimmunity. The emergence of many successful biological therapies targeting cytokines and cytokine receptors exemplifies the importance of cytokines in driving human autoimmune disease; unsurprisingly, there is no paucity of reviews on this subject. Nonetheless, many patients with autoimmune disease do not respond to biologicals, and cure remains an unmet goal. Thus, targeting the intracellular pathways employed by cytokines provides new therapeutic opportunities. A subset of cytokines utilizes the Janus kinase-signal transducer of activators of transcription (JAK-STAT) pathway as a mode of signal transduction. First generation JAK inhibitors (jakinibs) are used to treat rheumatologic disease, and second-generation jakinibs are being developed. Simultaneously, rapid advances are being made in our understanding of the genomic and epigenomic impact of cytokines. In this review, we will briefly review the role of JAK-STAT-dependent cytokines in immune-mediated disease, the current status of Jakinibs, and future possibilities for therapeutic intervention using genomic insights.

Transcriptomic profiling of long non-coding RNAs in dermatomyositis by microarray analysis

Long non-coding RNAs (lncRNAs) are prevalently transcribed in the genome and have been found to be of functional importance. However, the potential roles of lncRNAs in dermatomyositis (DM) remain unknown. In this study, a lncRNA + mRNA microarray analysis was performed to profile lncRNAs and mRNAs from 15 treatment-naive DM patients and 5 healthy controls. We revealed a total of 1198 lncRNAs (322 up-regulated and 876 down-regulated) and 1213 mRNAs (665 up-regulated and 548 down-regulated) were significantly differentially expressed in DM patients compared with the healthy controls (fold change>2, P < 0.05). Subgrouping DM patients according to the presence of interstitial lung disease and anti-Jo-1 antibody revealed different expression patterns of the lncRNAs. Pathway and gene ontology analysis for the differentially expressed mRNAs confirmed that type 1 interferon signaling was the most significantly dysregulated pathway in all DM subgroups. In addition, distinct pathways that uniquely associated with DM subgroup were also identified. Bioinformatics prediction suggested that linc-DGCR6-1 may be a lncRNA that regulates type 1 interferon-inducible gene USP18, which was found highly expressed in the perifascicular areas of the muscle fibers of DM patients. Our findings provide an overview of aberrantly expressed lncRNAs in DM muscle and further broaden the understanding of DM pathogenesis.

Association between TYK2 polymorphisms and susceptibility to autoimmune rheumatic diseases: a meta-analysis

Objective

This study aimed to explore whether TYK2 polymorphisms are associated with susceptibility to autoimmune rheumatic diseases.

Methods

We conducted a meta-analysis on the association between TYK2 polymorphisms and autoimmune rheumatic diseases.

Results

Twelve studies with a total of 16,335 patients and 30,065 controls were included in the meta-analysis. Meta-analysis revealed an association between rheumatic diseases and the 2 allele of the TYK2 rs2304256 (OR = 0.885, 95% CI = 0.802–0.978, p = 0.016). Furthermore, stratification by ethnicity identified a significant association between this polymorphism and rheumatic diseases in Caucasians (OR = 0.822, 95% CI = 0.706–0.889, p = 9.5 × 10−7), but not in Asians (OR = 1.127, 95% CI = 0.835–1.522, p = 0.434). Meta-analysis by rheumatic disease type revealed a significant association between the 2 allele of the TYK2 rs2304256 and SLE in Caucasians (OR = 0.737, 95% CI = 0.673–0.808, p < 1.0 × 10−8) but not in Asians (OR = 1.211, 95% CI = 0.813–1.804, p = 0.347). Meta-analysis revealed that the rs12720356 polymorphism was associated with susceptibility to rheumatic diseases in Caucasians (OR = 0.812, 95% CI = 0.661–0.997, p = 0.046) but not in Asians. Interestingly, the rs280519 polymorphism was significantly associated with susceptibility to SLE both in Caucasians and Asians. However, no associations were found between the rs12720270, rs280500, rs280523 and rs8108236 polymorphisms and susceptibility to rheumatic diseases.

Conclusions

This meta-analysis demonstrates that the TYK2 rs2304256 and rs12720356 polymorphisms are associated with susceptibility to rheumatic diseases, rs2304256 polymorphism is associated with SLE in Caucasians, and rs280519 polymorphism is associated with SLE in Caucasians and Asians.

Single nucleotide polymorphisms in the FAM167A-BLK gene are associated with polymyositis/dermatomyositis in the Han Chinese population

Idiopathic inflammatory myopathies (IIMs) are autoimmune diseases influenced by genetic background and environmental factors. Recently, FAM167A-BLK gene has been identified as a potential genetic susceptibility locus for dermatomyositis (DM) in patients of European and Japanese populations. Our aim here was to investigate the association between FAM167A-BLK polymorphisms and IIMs risk in Chinese Han. The FAM167A-BLK single nucleotide polymorphisms (SNPs) rs2736340, rs7812879, rs13277113, rs2618479, rs2254546 and rs2248932 were analyzed in polymyositis (PM) patients (n = 310), DM patients (n = 535) and 968 ethnically matched healthy controls, with the Sequenom MassArray system. Our present study demonstrated that strong allele association was observed in overall PM/DM and PM patients for rs2736340 (P_c = 6.48 × 10⁻³; P_c = 0.013, respectively), rs7812879 (P_c = 0.017; P_c = 0.034, respectively) and rs13277113 (P_c = 0.011; P_c = 0.047, respectively). These three SNPs were significantly associated with interstitial lung disease (ILD) in overall PM/DM patients (all, P_c < 0.05). The frequency of the five haplotypes of the five SNPs (rs2736340, rs7812879, rs13277113, rs2618479 and rs2254546) was also significantly different between overall PM/DM, PM or DM patients and healthy controls. This was the first study to demonstrate that the FAM167A-BLK polymorphisms were associated with Chinese PM/DM patients or these patients with ILD, indicating that PM/DM might share common gene with other autoimmune diseases.

Tyrosine kinase 2 - Surveillant of tumours and bona fide oncogene

Tyrosine kinase 2 (TYK2) is a member of the Janus kinase (JAK) family, which transduces cytokine and growth factor signalling. Analysis of TYK2 loss-of-function revealed its important role in immunity to infection, (auto-) immunity and (auto-) inflammation. TYK2-deficient patients unravelled high similarity between mice and men with respect to cellular signalling functions and basic immunology. Genome-wide association studies link TYK2 to several autoimmune and inflammatory diseases as well as carcinogenesis. Due to its cytokine signalling functions TYK2 was found to be essential in tumour surveillance. Lately TYK2 activating mutants and fusion proteins were detected in patients diagnosed with leukaemic diseases suggesting that TYK2 is a potent oncogene. Here we review the cell intrinsic and extrinsic functions of TYK2 in the characteristics preventing and enabling carcinogenesis. In addition we describe an unexpected function of kinase-inactive TYK2 in tumour rejection.

Dense genotyping of immune-related loci in idiopathic inflammatory myopathies confirms HLA alleles as the strongest genetic risk factor and suggests different genetic background for major clinical subgroups

OBJECTIVES

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases characterised by muscle weakness and extramuscular manifestations such as skin rashes and interstitial lung disease. We genotyped 2566 IIM cases of Caucasian descent using the Immunochip; a custom array covering 186 established autoimmune susceptibility loci. The cohort was predominantly comprised of patients with dermatomyositis (DM, n=879), juvenile DM (JDM, n=481), polymyositis (PM, n=931) and inclusion body myositis (n=252) collected from 14 countries through the Myositis Genetics Consortium.

RESULTS

The human leucocyte antigen (HLA) and PTPN22 regions reached genome-wide significance (p<5×10(-8)). Nine regions were associated at a significance level of p<2.25×10(-5), including UBE2L3, CD28 and TRAF6, with evidence of independent effects within STAT4. Analysis of clinical subgroups revealed distinct differences between PM, and DM and JDM. PTPN22 was associated at genome-wide significance with PM, but not DM and JDM, suggesting this effect is driven by PM. Additional suggestive associations including IL18R1 and RGS1 in PM and GSDMB in DM were identified. HLA imputation confirmed that alleles HLA-DRB1*03:01 and HLA-B*08:01 of the 8.1 ancestral haplotype (8.1AH) are most strongly associated with IIM, and provides evidence that amino acids within the HLA, such as HLA-DQB1 position 57 in DM, may explain part of the risk in this locus. Associations with alleles outside the 8.1AH reveal differences between PM, DM and JDM.

CONCLUSIONS

This work represents the largest IIM genetic study to date, reveals new insights into the genetic architecture of these rare diseases and suggests different predominating pathophysiology in different clinical subgroups.

Genetics of Interstitial Lung Disease: Vol de Nuit (Night Flight)

Interstitial lung disease (ILD) is a chronic, progressive fibrotic lung disease with a dismal prognosis. ILD of unknown etiology is referred to as idiopathic interstitial pneumonia (IIP), which is sporadic in the majority of cases. ILD is frequently accompanied by rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), and other autoimmune diseases, and is referred to as collagen vascular disease-associated ILD (CVD-ILD). Susceptibility to ILD is influenced by genetic and environmental factors. Recent advances in radiographic imaging techniques such as high-resolution computed tomography (CT) scanning as well as high-throughput genomic analyses have provided insights into the genetics of ILD. These studies have repeatedly revealed an association between IIP (sporadic and familial) and a single nucleotide polymorphism (SNP) in the promoter region of the mucin 5B (MUC5B). HLA-DRB1*11 alleles have been reported to correlate with ILD in European patients with SSc, whereas in Japanese patients with RA, the HLA-DR2 serological group was identified. The aim of this review is to describe the genetic background of sporadic IIP, CVD-ILD, drug-induced-ILD (DI-ILD), pneumoconiosis, and hypersensitivity pneumonitis. The genetics of ILD is still in progress. However, this information will enhance the understanding of the pathogenesis of ILD and aid the identification of novel therapeutic targets for personalized medicine in future.