Brief Report: Autoantibodies to DNA Mismatch Repair Enzymes in Polymyositis/Dermatomyositis and Other Autoimmune Diseases: A Possible Marker of Favorable Prognosis: Autoantibodies to DNA Mismatch Repair Enzymes in PM/DM

Immune recognition of lysyl-tRNA synthetase and isoleucyl-tRNA synthetase by anti-OJ antibody-positive sera

OBJECTIVE

Anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies are useful for identifying a clinical subset of patients with idiopathic inflammatory myopathies (IIMs). Anti-OJ antibodies, which recognize multi-enzyme synthetase complexes including isoleucyl-tRNA synthetase (IARS) and lysyl-tRNA synthetase (KARS), are among the anti-ARS antibodies. Although testing antibodies to other ARSs have been used clinically, no validated immunoassays for detecting anti-OJ antibodies are available. We aimed to establish an anti-OJ ELISA.

METHODS

Serum samples were collected from 279 patients with IIMs and 22 patients with idiopathic interstitial pneumonia. Sixty-four of the samples that had been confirmed to be negative for anti-OJ by standard immunoprecipitation were used as the negative control, and 12 anti-OJ-positive reference sera were used as the positive control. Antibodies to IARS and KARS were assayed by ELISA using biotinylated recombinant proteins generated by in vitro transcription/translation.

RESULTS

The anti-OJ-positive sera strongly reacted with the KARS and IARS recombinant proteins in ELISA. Although all 12 reference sera were positive in the anti-KARS ELISA, 4 of the 64 anti-OJ-negative sera were also weakly positive. The sensitivity and the specificity were 100% and 93.8%, respectively. Since our anti-KARS ELISA performed well, showing a high agreement with the results for immunoprecipitation (Cohen's κ > 0.8), the remaining 237 samples were also tested. Thirteen anti-KARS-positive sera were newly found by ELISA, all of which were anti-OJ positive by immunoprecipitation.

CONCLUSION

Immunoassays for detecting anti-OJ antibodies using KARS and IARS recombinant proteins were developed. Our ELISAs performed well, with very high agreement of the results by immunoprecipitation and can be applied to the first reliable, easy-to-use measurement assays for anti-OJ antibodies.

Prominent roles of microRNA-142 in cancer

MicroRNAs (miRNAs) are single-stranded non-coding RNAs that regulate gene expression post-transcriptionally via mRNA degradation, or translational repression. They have important roles in normal development and homeostasis maintenance. Many studies have revealed that aberrant expression of miRNAs is associated with development of pathological conditions, including cancers. MiRNAs can either promote or suppress tumorigenesis based on the regulation of gene expression by targeting multiple molecules. In recent years, several miRNAs have been reported to be dysregulated in various cancers. Most recent findings have shown that miR-142 gene, located at chromosome 17q22, is involved in cellular migration, proliferation, and apoptosis in different human cancers. The present review discusses some molecular mechanisms and the expression status of miRNA-142 in the pathogenesis of various cancers.

Survivin modulatory role in autoimmune and autoinflammatory diseases

Baculoviral IAP repeat containing 5 (BIRC5) gene encodes the important protein as survivin, a multifunctional protein, which is involved in cellular and molecular networks, progression of cell cycle, homeostasis, developmental morphogenesis, and apoptosis. The proximal BIRC5 promoter possesses specific binding sites for key transcription factors such as nuclear factor κB and signal transducer and activator of transcription 3. Upregulation of survivin exacerbates the autoimmune diseases (AIDs) including multiple sclerosis and myasthenia gravis by reducing the activity threshold of survivin-specific cytotoxic T cells. DNA damage along with upregulation or downregulation of survivin have been demonstrated in initiation and pathogenesis of cancers and AIDs. However, detailed mechanism of survivin function in pathogenesis of AIDs is not well understood. This review focuses on the structure, specificity, regulation, and function of survivin in physiologic conditions and pathogenesis of AIDs.

Clinical significance of myositis-specific autoantibodies

To date, increasing numbers of myositis-specific autoantibodies (MSAs) have been reported and their clinical significance has been elucidated. Anti-aminoacyl-tRNA synthetase (ARS) and anti-melanoma-differentiation associated gene 5 (MDA5) are strongly associated with interstitial lung disease (ILD); however, the clinical course of ILD is different depending on which autoantibody is present. Anti-ARS is associated with chronic and repetitive ILD and anti-MDA5 is associated with rapidly progressive ILD. Anti-MDA5, anti-transcriptional intermediary factor (TIF) 1-γ, anti-nuclear matrix protein (NXP) 2 and anti-Mi-2 antibodies are dermatomyositis specific. Anti-TIF1-γ and anti-NXP-2 antibodies are associated with malignancy, and anti-signal recognition particle (SRP) and anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibodies are associated with immune-mediated necrotizing myopathy (IMNM). Prognosis is also different among MSA-positive patient groups. Thus, MSAs are of great use for predicting disease course, prognosis, and determining therapeutic strategy as well as the diagnosis of idiopathic inflammatory myopathy (IIM) patients. Investigation of the pathogenic role of MSAs and their corresponding autoantigens will help us to understand the pathophysiology of IIM and identify new therapeutic targets.

Novel minor HLA DR associated antigens in type 1 diabetes

Type 1 diabetes is an autoimmune disease leading to insulin deficiency. Autoantibodies to beta cell proteins are already present in the asymptomatic phase of type 1 diabetes. Recent findings have suggested a number of additional minor autoantigens in patients with type 1 diabetes. We have established luciferase immunoprecipitation systems (LIPS) for anti-MTIF3, anti-PPIL2, anti-NUP50 and anti-MLH1 and analyzed samples from 500 patients with type 1 diabetes at onset of clinical disease and 200 healthy individuals who had a family history of type 1 diabetes but no evidence of beta cell autoantibodies. We show significantly higher frequencies of anti-MTIF3, anti-PPIL2 and anti-MLH1 in recent onset type 1 diabetes patients in comparison to controls. In addition, antibodies to NUP50 were associated with HLA-DRB1*03 and antibodies to MLH1 were associated with HLA-DRB1*04 genotypes.

Bench to bedside review of myositis autoantibodies

Idiopathic inflammatory myopathies represent a heterogeneous group of autoimmune diseases with systemic involvement. Even though numerous specific autoantibodies have been recognized, they have not been included, with the only exception of anti-Jo-1, into the 2017 Classification Criteria, thus perpetuating a clinical-serologic gap. The lack of homogeneous grouping based on the antibody profile deeply impacts the diagnostic approach, therapeutic choices and prognostic stratification of these patients. This review is intended to highlight the comprehensive scenario regarding myositis-related autoantibodies, from the molecular characterization and biological significance to target antigens, from the detection tools, with a special focus on immunofluorescence patterns on HEp-2 cells, to their relative prevalence and ethnic diversity, from the clinical presentation to prognosis. If, on the one hand, a notable body of literature is present, on the other data are fragmented, retrospectively based and collected from small case series, so that they do not sufficiently support the decision-making process (i.e. therapeutic approach) into the clinics.

Autoantibodies to Su/Argonaute 2 in Japanese patients with inflammatory myopathy

BACKGROUND

Anti-Su antibodies are found in 5-20% of cases of various systemic autoimmune rheumatic diseases and in 5-10% of dermatomyositis (DM)/polymyositis (PM) patients. In 2006, the 100kDa Su antigen was identified as argonaute2 (Ago2), and it was found to play a major role in RNA interference. However, immunoprecipitation (IP) remains the main method for detecting anti-Su and the clinical significance of the antibodies is uncertain.

METHODS

Sera from patients with DM/PM (n=224) were screened by an ELISA that uses recombinant biotinylated Ago2 protein. Some serum samples were tested by IP and by indirect immunofluorescence (IIF) analysis.

RESULTS

Seventeen (7.5%, 17/224) sera from DM/PM were positive in ELISA. Of the 33 IP-tested sera (17 ELISA-positive and 16 ELISA-negative with high background), 13 were found to be anti-Ago2/Su-positive in IP and ELISA. Only one IP-positive serum was judged to be ELISA-negative. Among the 13 patients with anti-Su/Ago2, 7 cases also had myositis-specific autoantibodies. Six sera that were positive by both IP and ELISA showed the GW body pattern in IIF. Interestingly, one ELISA-positive serum with an inconclusive result in IP also showed the GW body pattern.

CONCLUSION

Our novel ELISA appears to be useful for screening anti-Su/Ago2 antibodies (sensitivity: 93%, specificity: 79%).

DEPTOR-mTOR Signaling Is Critical for Lipid Metabolism and Inflammation Homeostasis of Lymphocytes in Human PBMC Culture

Abnormal immune response of the body against substances and tissues causes autoimmune diseases, such as polymyositis, dermatomyositis, and rheumatoid arthritis. Irregular lipid metabolism and inflammation may be a significant cause of autoimmune diseases. Although much progress has been made, mechanisms of initiation and proceeding of metabolic and inflammatory regulation in autoimmune disease have not been well-defined. And novel markers for the detection and therapy of autoimmune disease are urgent. mTOR signaling is a central regulator of extracellular metabolic and inflammatory processes, while DEP domain-containing mTOR-interacting protein (DEPTOR) is a natural inhibitor of mTOR. Here, we report that overexpression of DEPTOR reduces mTORC1 activity in lymphocytes of human peripheral blood mononuclear cells (PBMCs). Combination of DEPTOR overexpression and mTORC2/AKT inhibitors effectively inhibits lipogenesis and inflammation in lymphocytes of PBMC culture. Moreover, DEPTOR knockdown activates mTORC1 and increases lipogenesis and inflammations. Our findings provide a deep insight into the relationship between lipid metabolism and inflammations via DEPTOR-mTOR pathway and imply that DEPTOR-mTOR in lymphocytes of PBMC culture has the potential to be as biomarkers for the detection and therapies of autoimmune diseases.

Cutaneous Manifestations in Dermatomyositis: Key Clinical and Serological Features-a Comprehensive Review

Dermatomyositis (DM) is a common idiopathic inflammatory myopathy. The pathogenesis is considered to be microangiopathy affecting skin and muscle. The cutaneous manifestations of DM are the most important aspect of this disease, and their correct evaluation is important for early diagnosis. The skin signs are various: Some are pathognomonic or highly characteristic, and others are compatible with DM. Recently, DM has been categorized into several disease subsets based on the various autoantibodies present in patients. Sometimes, characteristic cutaneous manifestations are strongly associated with the presence of specific autoantibodies. For example, anti-Mi-2 antibody is associated with the classic features of DM, including heliotrope rash, Gottron's papules, the V-neck sign, the shawl sign, cuticular overgrowth, and photosensitivity. Frequent cutaneous features in anti-transcriptional intermediary factor 1 gamma (TIF1γ)-positive patients are diffuse photoerythema, including "dusky red face," while skin ulcerations, palmar papules (inverse Gottron), diffuse hair loss, panniculitis, and oral pain and/or ulcers are sometimes associated with anti-melanoma differentiation-associated gene 5 product (MDA5) antibody. Here, we review important cutaneous manifestations seen in patients with DM, and we examine the relationship between the skin changes and myositis-associated autoantibodies. Correct evaluation of cutaneous manifestations and myositis-associated autoantibodies should help the clinician in the early diagnosis of DM, for a quick recognition of cutaneous signs that may be the symptom of onset before muscle inflammation.

Identification of Palmitoleic Acid Controlled by mTOR Signaling as a Biomarker of Polymyositis

Polymyositis (PM) is a chronic disease characterized by muscle pain, weakness, and increase in muscle-related enzymes, accompanied with inflammations in lymphocytes. However, it is not well understood how the molecular alternations in lymphocytes contribute to the development of polymyositis. The mechanistic target of rapamycin (mTOR) signaling is the central regulator of metabolism and inflammation in mammalian cells. Based on previous studies, we proposed that mTOR signaling may control inflammatory reactions via lipid metabolism. In this study, we aim to figure out the role of mTOR signaling in the development of polymyositis and identify novel biomarkers for the detection and therapy of polymyositis. After screening and validation, we found that palmitoleic acid, a monounsaturated fatty acid, is highly regulated by mTOR signaling. Inhibition of mTORC1 activity decreases palmitoleic acid level. Moreover, mTORC1 regulates the level of palmitoleic acid by controlling its de novo synthesis. Importantly, increased palmitoleic acid has been proven to be a marker of polymyositis. Our work identifies palmitoleic acid in peripheral blood mononuclear cells (PBMC) as a biomarker of polymyositis and offers new targets to the clinical therapy.

Anti-PM/Scl antibodies are found in Japanese patients with various systemic autoimmune conditions besides myositis and scleroderma

Introduction

Anti-PM/Scl antibodies are associated with polymyositis (PM)/systemic scleroderma (SSc) overlap syndromes and are also found in other systemic autoimmune diseases. Although anti-PM/Scl reactivity is found in 3-11% of PM or SSc patients and in approximately 25% of PM/SSc overlap patients, previous large studies of Japanese patients with scleroderma reported that anti-PM/Scl are not found in Japanese patients at all. The PM/Scl autoantigen complex comprises 11–16 different polypeptides; ELISA with PM1-α peptide, which is a major epitope of the PM/Scl complex, has frequently been used for the detection of these antibodies in recent studies. However, no ELISA kit is commercially available in Japan.

Methods

In this study, we developed an immunoassay for measuring antibodies against recombinant PM/Scl-100 and PM/Scl-75 polypeptides, which are the two major targets of the complex, and we investigated their presence in 600 Japanese patients with various systemic autoimmune conditions. Immunoprecipitation analysis using the recombinants in addition to traditional radiolabeled cell extracts were also applied to ELISA-positive sera.

Results

In ELISA, 11 patients were positive for anti-PM/Scl-100 antibodies and 7 of these 11 patients were also positive for anti-PM/Scl-75 antibodies. Immunoprecipitation analysis using the recombinants in addition to traditional radiolabeled cell extracts confirmed that 9 out of these 11 patients immunoprecipitated the typical sets of PM/Scl proteins. In total, 4/16 (25%) undifferentiated connective tissue disease (UCTD) patients, 3/126 (2.4%) dermatomyositis patients, 1/223 (0.4%) SSc patients, 1/88 (1.1%) Sjögren’s syndrome patients, 0/123 patients with systemic lupus erythematosus, 0/17 patients with overlap syndrome and 0/7 patients with PM were judged to be positive for anti-PM/Scl antibodies.

Conclusions

This is the first report of Japanese autoimmune patients with anti-PM/Scl antibodies. In Japanese patients, anti-PM/Scl antibodies are only very rarely found, and they are not always specific for dermatomyositis (DM) or SSc; they are also present in various autoimmune conditions with the highest prevalence being in UCTD. All anti-PM/Scl-positive DM cases are complicated with interstitial lung disease and/or cancer, while no life-threatening involvement was found in other anti-PM/Scl-positive cases. Further studies on larger cohorts are necessary to define the clinical significance of anti-PM/Scl antibodies in autoimmune diseases.