Prognostic significance of natural killer cell depletion in predicting progressive fibrosing interstitial lung disease in idiopathic inflammatory myopathies.

Objectives: Interstitial lung disease (ILD) is one of the common extramuscular involvement in idiopathic inflammatory myopathies (IIMs) (1). Several patients develop a progressive fibrosing ILD (PF-ILD) despite conventional treatment, resulting in a progressive deterioration in their quality of life (2). Here, we investigated the clinical and immune characteristics of IIM-ILD and risk factors for PF-ILD in IIM, mainly in anti-melanoma differentiation-associated protein 5 (anti-MDA5+) dermatomyositis (DM) and anti-synthetase syndrome (ASS). Methods: Here, a prospective cohort of 156 patients with IIM-ILD were included in the longitudinal analysis and divided into the PF-ILD (n=65) and non-PF-ILD (n=91) groups, and their baseline clinical characteristics were compared. Univariate and multivariate Cox analyses were performed to identify the variables significantly associated with pulmonary fibrosis progression in the total cohort, then anti-MDA5+ DM and ASS groups separately. Results: Peripheral blood lymphocyte counts, including T, B, and NK cell counts, were significantly lower in the PF-ILD group than in the non-PF-ILD group. This characteristic is also present in the comparison between patients with anti-MDA5+ DM and ASS. The multivariate Cox regression analysis revealed that age > 43.5 years [HR: 7.653 (95% CI: 2.005-29.204), p = 0.003], absolute NK cell count < 148 cells/µL [HR: 6.277 (95% CI: 1.572-25.067), p = 0.009] and absolute Th cell count < 533.2 cells/µL [HR: 4.703 (95% CI: 1.014-21.821), p = 0.048] were independent predictors of progressive fibrosing during 1-year follow-up for patients with anti-MDA5+ DM, while absolute count of NK cells < 303.3 cells/µL [HR: 19.962 (95% CI: 3.108-128.223), p = 0.002], absolute count of lymphocytes < 1.545×109/L [HR: 9.684 (95% CI: 1.063-88.186), p = 0.044], and ferritin > 259.45 ng/mL [HR: 6 (95% CI: 1.116-32.256), p = 0.037] were independent predictors of PF-ILD for patients with ASS. Conclusions: Patients with anti-MDA5+ DM and ASS have independent risk factors for PF-ILD. Lymphocyte depletion (particularly NK cells) was significantly associated with PF-ILD within 1-year of follow-up for IIM-ILD.

Myositis Autoantibody Profiles and Clinical Significance in Patients with Inflammatory Myopathies in Southwest China.

BACKGROUND: The purpose of this study is to analyze the distribution of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) in patients with idiopathic inflammatory myopathies (IIMs) in southwest China and to explore the relevance between each subtype, each clinical feature, and to explore the relevance between the laboratory indexes. METHODS: For this study, 200 patients with IIMs were tested for myositis autoantibodies. Clinical manifestations and laboratory metrics were collected and the correlations between autoantibodies and clinical phenotypes were analyzed. RESULTS: MSAs were found in 73.5% of the patients. The most frequently MSAs were anti-MDA5 (26.8%), followed by anti-ARS (18.5%). Anti-Ro52 was the most prevalent in MAAs (46.2%). Interstitial lung disease (ILD) and arthralgia were more frequent in anti-MDA5 and anti-Jo-1 positive groups (each p < 0.05). Anti-TIF1-γ and anti-NXP2 were associated with dysphagia (each p < 0.05). Different antibody subtypes were associated with laboratory indicators of response to muscle damage and immune status. Logistic regression showed that anti-MDA5 and anti-Jo-1 were independent risk factors for ILD (OR = 4.542, p = 0.004; OR = 4.290, p = 0.018, respectively) and arthralgia (OR = 7.856, p = 0.000; OR = 5.731, p = 0.004, respectively), whereas anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia (OR = 4.521, p = 0.009; OR = 6.889, p = 0.017, respectively). CONCLUSIONS: Different antibody subtypes were associated with specific clinical features. Anti-MDA5 and anti-Jo-1 were independent risk factors for ILD and arthralgia. Anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia.

Mammalian reovirus µ1 protein attenuates RIG-I and MDA5-mediated signaling transduction by blocking IRF3 phosphorylation and nuclear translocation.

Mammalian reovirus (MRV) is a non-enveloped, gene segmented double-stranded RNA (dsRNA) virus. It is an important zoonotic pathogen that infects many mammals and vertebrates that act as natural hosts and causes respiratory and digestive tract diseases. Studies have reported that RIG-I and MDA5 in the innate immune cytoplasmic RNA-sensing RIG-like receptor (RLR) signaling pathway can recognize dsRNA from MRV and promote antiviral type I interferon (IFN) responses. However, the mechanism by which many MRV-encoded proteins evade the host innate immune response remains unclear. Here, we show that exogenous µ1 protein promoted the proliferation of MRV in vitro, while knockdown of MRV µ1 protein expression by shRNA could impair MRV proliferation. Specifically, µ1 protein inhibited MRV or poly(I:C)-induced IFN-ß expression, and attenuated RIG-I/MDA5-mediated signaling axis transduction during MRV infection. Importantly, we found that µ1 protein significantly decreased IFN-ß mRNA expression induced by MDA5, RIG-I, MAVS, TBK1, IRF3(5D), and degraded the protein expression of exogenous MDA5, RIG-I, MAVS, TBK1 and IRF3 via the proteasomal and lysosomal pathways. Additionally, we show that µ1 protein can physically interact with MDA5, RIG-I, MAVS, TBK1, and IRF3 and attenuate the RIG-I/MDA5-mediated signaling cascades by blocking the phosphorylation and nuclear translocation of IRF3. In conclusion, our findings reveal that MRV outer capsid protein µ1 is a key factor in antagonizing RLRs signaling cascades and provide new strategies for effective prevention and treatment of MRV infection.

Spontaneous pneumomediastinum: An extra muscular manifestation of anti-MDA5 dermatomyositis. Report of 2 cases.

The use of specific antibodies in inflammatory myopathies has improved the characterization of this disease, identifying different clinical phenotypes. Patients with dermatomyositis (DM) and anti-MDA5 antibodies display typical skin symptoms, lesser muscular involvement, and a prevalence of interstitial lung disease (ILD) of up to 91%. Beyond ILD, spontaneous pneumomediastinum (SN) has been identified as a rare but potentially fatal pulmonary manifestation. Two cases of this complication in patients with anti-MDA5 DM are reported.

Assessing Time of Onset for Interstitial Lung Disease in Anti-MDA5 Antibody-Positive Dermatomyositis.

This cohort study seeks to describe the time interval between interstitial lung disease and anti­melanoma differentiation-associated gene 5 antibody-positive dermatomyositis diagnoses.

Autoimmunity against melanoma differentiation-associated gene 5 induces interstitial lung disease mimicking dermatomyositis in mice.

Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM) is characterized by amyopathic DM with interstitial lung disease (ILD). Patients with anti-MDA5 antibody-associated ILD frequently develop rapidly progression and present high mortality rate in the acute phase. Here, we established a murine model of ILD mediated by autoimmunity against MDA5. Mice immunized with recombinant murine MDA5 whole protein, accompanied with complete Freund's adjuvant once a week for four times, developed MDA5-reactive T cells and anti-MDA5 antibodies. After acute lung injury induced by intranasal administration of polyinosinic-polycytidylic acid [poly (I:C)] mimicking viral infection, the MDA5-immunized mice developed fibrotic ILD representing prolonged respiratory inflammation accompanied by fibrotic changes 2 wk after poly (I:C)-administration, while the control mice had quickly and completely recovered from the respiratory inflammation. Treatment with anti-CD4 depleting antibody, but not anti-CD8 depleting antibody, suppressed the severity of MDA5-induced fibrotic ILD. Upregulation of interleukin (IL)-6 mRNA, which was temporarily observed in poly (I:C)-treated mice, was prolonged in MDA5-immunized mice. Treatment with anti-IL-6 receptor antibody ameliorated the MDA5-induced fibrotic ILD. These results suggested that autoimmunity against MDA5 exacerbates toll-like receptor 3-mediated acute lung injury, and prolongs inflammation resulting in the development of fibrotic ILD. IL-6 may play a key role initiating ILD in this model.

Elevated serum B-cell activator factor levels predict rapid progressive interstitial lung disease in anti-melanoma differentiation associated protein 5 antibody positive dermatomyositis.

BACKGROUND: Rapid progressive interstitial lung disease (RP-ILD) is the leading cause of anti-melanoma differentiation associated protein 5 antibody positive dermatomyositis (anti-MDA5+DM) related death. Elevated serum B-cell activating factor (BAFF) levels have been implicated in connective tissue diseases associated ILD. Here, we evaluate whether BAFF could be a prognostic biomarker for predicting RP-ILD in anti-MDA5+DM patients. METHODS: Serums were collected from 39 patients with anti-MDA5+DM (20 with RP-ILD and 19 with non-RP-ILD), 20 antisynthase syndrome (ASS) patients and 20 healthy controls (HC). BAFF concentration was measured by an enzyme-linked immunosorbent assay. RESULTS: Serum BAFF level was higher in anti-MDA5+DM patients than those in ASS patients and HC (3882.32 ± 1880.09 vs. 2540.89 ± 1403.04 and 2486.28 ± 767.97 pg/mL, p = 0.0056 and 0.0038, respectively). Within anti-MDA5+DM groups, RP-ILD patients exhibited higher BAFF concentration than non-RP-ILD group (4549.78 ± 1839.97 vs. 3297.28 ± 1794.69 pg/mL, p = 0.04). The BAFF concentration was positively correlated with levels of C-reactive protein (CRP), dehydrogenase (LDH) and cytokeratin (CK) in anti-MDA5+DM patients (r = 0.350, p = 0.035; r = 0.393, p = 0.016; r = 0.518, p = 0.001; respectively). The best cut-off value of BAFF concentration was 2971.5 pg/mL by ROC curve (AUC area = 0.690, p = 0.045) and BAFF > 2971.5 pg/mL was an independent risk factor for RP-ILD using multivariate analysis (OR = 9.389, 95% CI = 1.609-54.769; p = 0.013). CONCLUSIONS: Serum BAFF could be a useful prognostic biomarker for early detecting RP-ILD risk in anti-MDA5+DM patients.

Pembrolizumab-associated anti-MDA5 dermatomyositis in a patient with lung cancer: a first case report.

We report the first case of anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis as a systemic immune-related adverse event in a 64-year-old man receiving pembrolizumab to treat advanced lung cancer. The patient experienced hypothyroidism, myalgia, skin involvement, dyspnoea and diarrhoea. Laboratory tests revealed raised inflammatory markers, hypercreatinekinasemia and anti-MDA5 autoantibodies. Electroneuromyography and pathognomonic signs on physical examination confirmed the diagnosis of pauci-myopathic dermatomyositis. Pembrolizumab was discontinued and immunosuppressive therapy led to rapid and progressive improvement, with complete remission of dermatomyositis. This case report widens the spectrum of systemic immune-related adverse events associated with pembrolizumab.

Genome-Wide Association Study Identifies IFIH1 and HLA-DQB1*05:02 Loci Associated With Anti-NMDAR Encephalitis.

BACKGROUND AND OBJECTIVES: Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a rare autoimmune neurologic disorder, the genetic etiology of which remains poorly understood. Our study aims to investigate the genetic basis of this disease in the Chinese Han population. METHODS: We performed a genome-wide association study and fine-mapping study within the major histocompatibility complex (MHC) region of 413 Chinese patients with anti-NMDAR encephalitis recruited from 6 large tertiary hospitals and 7,127 healthy controls. RESULTS: Our genome-wide association analysis identified a strong association at the IFIH1 locus on chromosome 2q24.2 (rs3747517, p = 1.06 × 10-8, OR = 1.55, 95% CI, 1.34-1.80), outside of the human leukocyte antigen (HLA) region. Furthermore, through a fine-mapping study of the MHC region, we discovered associations for 3 specific HLA class I and II alleles. Notably, HLA-DQB1*05:02 (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59) demonstrates the strongest association among classical HLA alleles, closely followed by HLA-A*11:01 (p = 4.36 × 10-7; OR, 1.52; 95% CI 1.29-1.79) and HLA-A*02:07 (p = 1.28 × 10-8; OR, 1.87; 95% CI 1.50-2.31). In addition, we uncovered 2 main HLA amino acid variation associated with anti-NMDAR encephalitis including HLA-DQß1-126H (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59), exhibiting a predisposing effect, and HLA-B-97R (p = 3.40 × 10-8; OR, 0.63; 95% CI 0.53-0.74), conferring a protective effect. Computational docking analysis suggested a close relationship between the NR1 subunit of NMDAR and DQB1*05:02. DISCUSSION: Our findings indicate that genetic variation in IFIH1, involved in the type I interferon signaling pathway and innate immunity, along with variations in the HLA class I and class II genes, has substantial implications for the susceptibility to anti-NMDAR encephalitis in the Chinese Han population.

Physiological functions of RIG-I-like receptors.

RIG-I-like receptors (RLRs) are crucial for pathogen detection and triggering immune responses and have immense physiological importance. In this review, we first summarize the interferon system and innate immunity, which constitute primary and secondary responses. Next, the molecular structure of RLRs and the mechanism of sensing non-self RNA are described. Usually, self RNA is refractory to the RLR; however, there are underlying host mechanisms that prevent immune reactions. Studies have revealed that the regulatory mechanisms of RLRs involve covalent molecular modifications, association with regulatory factors, and subcellular localization. Viruses have evolved to acquire antagonistic RLR functions to escape the host immune reactions. Finally, the pathologies caused by the malfunction of RLR signaling are described.

A case of autoimmune pulmonary alveolar proteinosis during the course of treatment of rapidly progressive interstitial pneumonia associated with anti-MDA5 antibody-positive dermatomyositis.

BACKGROUND: Autoimmune pulmonary alveolar proteinosis (APAP) is a diffuse lung disease that causes abnormal accumulation of lipoproteins in the alveoli; however, its pathogenesis remains unclear. Recently, APAP cases have been reported during the course of dermatomyositis. The combination of these two diseases may be coincidental; however, it may have been overlooked because differentiating APAP from a flare-up of interstitial pneumonia associated with dermatomyositis is challenging. This didactic case demonstrates the need for early APAP scrutiny. CASE PRESENTATION: A 50-year-old woman was diagnosed with anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive dermatitis and interstitial pneumonia in April 2021. The patient was treated with corticosteroids, tacrolimus, and cyclophosphamide pulse therapy for interstitial pneumonia complicated by MDA5 antibody-positive dermatitis, which improved the symptoms and interstitial pneumonia. Eight months after the start of treatment, a new interstitial shadow appeared that worsened. Therefore, three additional courses of cyclophosphamide pulse therapy were administered; however, the respiratory symptoms and interstitial shadows did not improve. Respiratory failure progressed, and 14 months after treatment initiation, bronchoscopy revealed turbid alveolar lavage fluid, numerous foamy macrophages, and numerous periodic acid-Schiff-positive unstructured materials. Blood test results revealed high anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody levels, leading to a diagnosis of APAP. The patient underwent whole-lung lavage, and the respiratory disturbance promptly improved. Anti-GM-CSF antibodies were measured from the cryopreserved serum samples collected at the time of diagnosis of anti-MDA5 antibody-positive dermatitis, and 10 months later, both values were significantly higher than normal. CONCLUSIONS: This is the first report of anti-MDA5 antibody-positive dermatomyositis complicated by interstitial pneumonia with APAP, which may develop during immunosuppressive therapy and be misdiagnosed as a re-exacerbation of interstitial pneumonia. In anti-MDA5 antibody-positive dermatomyositis, APAP comorbidity may have been overlooked, and early evaluation with bronchoalveolar lavage fluid and anti-GM-CSF antibody measurements should be considered, keeping the development of APAP in mind.

Multivariate logistic regression analysis of poor prognosis of dermatomyositis and clinical value of ferritin/Kl-6 in predicting prognosis.

BACKGROUND: Dermatomyositis (DM) is a rare inflammatory disease. Our research focuses on predicting poor prognosis in DM patients and evaluating the prognostic significance of ferritin and Salivary Sugar Chain Antigen-6 (KL-6) through multivariate logistic regression analysis. METHODS: Between February 2018 and April 2020, 80 DM patients at our hospital were categorized into MDA5 positive (n = 20) and negative (n = 60) groups. We conducted multivariate logistic regression to determine DM's poor prognosis risk factors and evaluate ferritin/KL-6's predictive value for prognosis. RESULTS: Analysis showed no gender, age, body mass index (BMI), or lifestyle (smoking, drinking) differences, nor in dyspnea, muscle weakness, skin ulcers, and acetylcysteine treatment effects (p > 0.05). Significant differences emerged in arrhythmias, interstitial pneumonia, C-reactive protein, albumin, and lactate dehydrogenase levels (p < 0.05). Before treatment, differences were negligible (p > 0.05), but post-treatment, serum KL-6 and ferritin levels dropped. MDA5 positive patients had elevated serum KL-6 and ferritin levels than survivors (p < 0.05), with a strong correlation to DM. Combined diagnosis using serum KL-6 and ferritin for DM prognosis showed area under curves of 0.716 and 0.634, significantly outperforming single-index diagnoses with an area under curve (AUC) of 0.926 (p < 0.05). CONCLUSION: Serum KL-6 and ferritin show marked abnormalities in DM, useful as indicators for evaluating polymyositis and DM conditions. However, the study's small sample size is a drawback. Expanding the sample size is essential to monitor serum KL-6 and ferritin changes in DM patients under treatment more closely, aiming to improve clinical assessment and facilitate detailed research.

Unique characteristics of anti-MDA-5 associated dermatomyositis in Southern California with a large Hispanic population.

OBJECTIVES: There is little to no data about the presentation and clinical course of anti-melanoma differentiation-associated gene-5 antibody (anti-MDA-5) dermatomyositis in a primarily U.S. Hispanic population. We describe the clinical course of anti-MDA-5 dermatomyositis in our majority Hispanic population. METHODS: This is a multicenter, retrospective case series of anti-MDA-5 dermatomyositis. Patients diagnosed with anti-MDA-5 dermatomyositis from June 2015 to March 2023 at four medical centers in Los Angeles, California, were included. Demographics and clinical characteristics were obtained. Descriptive statistics, Pearson's chi-squared, Fisher's exact, Wilcoxon rank sum, and Kruskal-Wallis tests were performed as applicable. RESULTS: Thirty anti-MDA-5 dermatomyositis patients were included. Twenty-two (73 %) were Hispanic. Twenty-one patients (70 %) were female, with a median age of 40.5 years. Hispanic patients were diagnosed with anti-MDA-5 dermatomyositis at a younger age than non-Hispanic patients (p = 0.025). Inflammatory arthritis was prominent; more males were affected than females (p = 0.027). Thirteen patients (43 %) were amyopathic. Twenty-five patients (83.3 %) had evidence of interstitial lung disease (ILD), and a higher ferritin level was associated with ILD (p = 0.049). There were six deaths (20 %); five (17 %) were ascribed to rapidly progressive ILD. CONCLUSION: ILD was the most common presentation of anti-MDA-5 dermatomyositis in our cohort and was associated with higher ferritin levels. Hispanic patients had a younger age of diagnosis than non-Hispanic patients. Necrotic skin lesions and inflammatory arthritis were frequently seen. This is the first study looking at clinical phenotypes and outcomes of anti-MDA-5 dermatomyositis in a primarily Hispanic U.S. POPULATION: Future studies are needed to better understand the clinical manifestations (to promptly recognize and treat) of this population of anti-MDA-5 dermatomyositis.

Treatment of myopathy and cutaneous ulcers in anti-MDA5-positive dermatomyositis with triple therapy.

Antimelanoma differentiation-associated protein 5 positive dermatomyositis (MDA5 DM) is a rare subtype of idiopathic inflammatory myopathy. There are limited data available regarding the cutaneous manifestations of MDA5 DM in the African American population. We presented the case of a male patient in his early 20s who presented with debilitating cutaneous ulceration and myopathy. Workup revealed interstitial lung disease (ILD) and positive MDA5 serology consistent with MDA5 DM. He made a remarkable recovery in terms of myopathy and cutaneous ulcerations with a multipronged regimen of prednisone, intravenous immunoglobulin and mycophenolate mofetil. However, there was a progression of ILD on this regimen which warranted use of rituximab.

Baricitinib for anti-melanoma differentiation-associated protein 5 antibody-positive dermatomyositis-associated interstitial lung disease: a case series and literature review on Janus kinase inhibitors for the disease.

Anti-melanoma differentiation-associated protein 5 antibody-positive dermatomyositis (anti-MDA5-DM) is frequently complicated by progressive interstitial lung disease (ILD), the prognosis of which is poor, and management is a major challenge. We treated three patients with anti-MDA5-DM-associated ILD (anti-MDA5-DM-ILD) using the Janus kinase (JAK) inhibitor, baricitinib, which improved lung opacities and saved two patients. We reviewed 6 patients with anti-MDA5-DM-ILD who had been treated with tofacitinib at our institution. Five of the patients survived, although discontinuation of tofacitinib due to complications was frequently observed. In addition, a literature search of patients with anti-MDA5-DM-ILD who were treated with JAK inhibitors yielded 21 articles involving 79 cases. All patients except one were treated with tofacitinib, and the survival rate was 75.9%. Although not statistically confirmed, the deceased patients tended to be older and had higher ferritin levels. A total of 92 complications were observed, 11 of which resulted in JAK inhibitor discontinuation. Cytomegalovirus reactivation comprised a substantial percentage of all complications and of those patients who required JAK inhibitor discontinuation. Five cases with fatal infective complications were also observed. While tofacitinib has been proposed to be a therapeutic option for anti-MDA5-DM-ILD, other JAK inhibitors, including baricitinib, are a treatment option. Further investigation is warranted to optimize treatment of anti-MDA5-DM-ILD.

Clinical and immunological features of COVID-19 in patients with anti-MDA5 dermatomyositis during the omicron wave in Chongqing, China.

Patients with anti-melanoma differentiation-associated gene 5 (anti-MDA5) dermatomyositis (DM) have a higher risk of coronavirus disease 2019 (COVID-19) infection. In this longitudinal observational study, we aimed to investigate the clinical and immunological features of these patients after COVID-19 infection. A total of 73 patients with anti-MDA5 DM were recruited from the Second Affiliated Hospital of Chongqing Medical University during the Omicron wave epidemic. Clinical data were collected by questionnaire survey and electronic medical records. Blood samples were used to determine the immunity responses. From December 9, 2022 to March 31, 2023, 67 patients were eligible for final analysis; 68.7% of them were infected with COVID-19. The most common symptoms observed in COVID-19 were upper respiratory symptoms, most cases were mild or moderate (97.8%). The clinical laboratory indexes were relativity stable in patients after infection (all p > 0.05). Vaccination is not a protective factor against the Omicron infection (odds ratio: 2.69, 95% confidence interval: 0.81-8.93, p = 0.105). Both wildtype (WT) neutralizing antibodies titer and BA.5-specific immunoglobulin G titer were significantly enhanced after infection (all p < 0.01), which was as high as healthy controls (HCs). The memory B-cell responses were similar between the patients with anti-MDA5 DM and HCs (p > 0.05). However, both the WT-specific CD8+ T cells and CD4+ T cells were reduced in patients with anti-MDA5 DM (all p < 0.05). In conclusion, patients with anti-MDA5 DM did not deteriorate the COVID-19, in turn, COVID-19 infection did not increase the risk of anti-MDA5 DM exacerbation. The humoral responses were robust but the cellular responses were weakened after COVID-19 infection.

Clinical, histologic and prognostic features of clinically amyopathic dermatomyositis.

OBJECTIVES: To characterise clinical amyopathic dermatomyositis (CADM) from a clinical, histological, and prognostic perspective. METHODS: We retrospectively recorded data from our DM cohort. Patients were categorised into three groups: classic DM, hypomyopathic DM (HDM), characterised by normal muscle strength and evidence of muscle involvement in laboratory tests and/or instrumental examinations and CADM, featured by normal muscle strength and unremarkable findings in both laboratory tests and instrumental examinations. Available muscle biopsies from each group were also compared. RESULTS: Our cohort included 63 DM (69.2%), 12 HDM (13.2%) and 16 CADM (17.6%) patients. Compared to DM, CADM patients were younger at onset and diagnosis (45.5±17 vs. 57±18, and 46±17 vs. 58±18 years, respectively; p<0.05). They were more likely to test positive for anti-MDA5 (37.5% vs. 4.8%) and anti- TIF1-γ (31.3% vs. 6.3%), had a higher incidence of arthritis (37.5% vs. 12.6%) and interstitial lung disease (ILD) (43.8% vs. 15.9%) (all comparisons with p<0.05). Muscle biopsies were available for 44 DM, 7 CADM, and 11 HDM patients, revealing similar sarcolemma MHC-I expression rates. Five-year survival rates were comparable across groups (DM: 74.6%, CADM: 75%, HDM: 83.3%). Cox analysis indicated the main mortality predictors in overall cohort were ILD (HR: 3.57, CI: 1.11-11.5) and cancer (HR: 3.67, CI: 1.17-11.5), not CADM (HR: 1.46, CI: 0.33-6.68). CONCLUSIONS: CADM patients differ in disease onset, autoantibody profiles, joint and lung involvement. While laboratory and instrumental tests have not shown muscle involvement in CADM, many muscle biopsies have shown MHC-I overexpression.

Type I interferon associated epistasis may contribute to early disease-onset and high disease activity in juvenile-onset lupus.

Pathologic type I interferon (T1IFN) expression is a key feature in systemic lupus erythematosus (SLE) that associates with disease activity. When compared to adult-onset disease, juvenile-onset (j)SLE is characterized by increased disease activity and damage, which likely relates to increased genetic burden. To identify T1IFN-associated gene polymorphisms (TLR7, IRAK1, miR-3142/miR-146a, IRF5, IRF7, IFIH1, IRF8, TYK2, STAT4), identify long-range linkage disequilibrium and gene:gene interrelations, 319 jSLE patients were genotyped using panel sequencing. Coupling phenotypic quantitative trait loci (QTL) analysis identified 10 jSLE QTL that associated with young age at onset (<12 years; IRAK1 [rs1059702], TLR7 [rs3853839], IFIH1 [rs11891191, rs1990760, rs3747517], STAT4 [rs3021866], TYK2 [rs280501], IRF8 [rs1568391, rs6638]), global disease activity (SLEDAI-2 K >10; IFIH1 [rs1990760], STAT4 [rs3021866], IRF8 [rs903202, rs1568391, rs6638]), and mucocutaneous involvement (TLR7 [rs3853839], IFIH1 [rs11891191, rs1990760]). This study suggests T1IFN-associated polymorphisms and gene:gene interrelations in jSLE. Genotyping of jSLE patients may allow for individualized treatment and care.

MAVS promotes interferon signaling in RNA virus infection by ZUFSP-mediated chromatin regulation.

Mitochondria serve as a platform for innate immune signaling transduction, and mitochondrial antiviral signaling protein (MAVS) is essential for interferon-ß (IFN-ß) production and innate antiviral immunity against RNA viruses. Here, we identified zinc finger-containing ubiquitin peptidase 1 (ZUFSP/ZUP1) as a MAVS-interacting protein by using proximity-based labeling technology in HEK293T and found it could act as a positive regulator of the retinoic acid-inducible gene-I (RIG-I)-like receptors(RLRs), including RIG-I and interferon-induced helicase C domain-containing protein 1 (MDA5). ZUFSP deficiency markedly inhibited RNA virus-triggered induction of downstream antiviral genes, and Zufsp-deficient mice were more susceptible to RNA virus infection. After RNA virus infection,ZUFSP was translocated from cytoplasm to nucleus and interacted with chromatin remodeling complex to facilitate the opening of IFN-stimulated gene (ISG) loci for transcription. This study provides a critical mechanistic basis for MAVS-regulated chromatin remodeling to promote interferon signaling.