Association between clinical phenotypes of dermatomyositis and polymyositis with myositis-specific antibodies and overlap systemic autoimmune diseases.

ABSTRACT: The aim of this study was to evaluate the association between clinical phenotypes of dermatomyositis (DM) and polymyositis (PM) with myositis-specific antibodies (MSAs), and overlap diagnosis of systemic autoimmune diseases.This cross-sectional study was conducted on 67 patients with DM and 27 patients with PM recruited from a regional hospital in southern Taiwan. Clinical phenotypes of DM and PM were assessed and MSAs were measured using a commercial line blot assay. The association of clinical phenotypes of DM and PM with MSAs and overlap diagnosis of systemic autoimmune diseases was performed using univariate and multiple logistic regression analyses.Clinically, patients with DM and PM and overlap diagnosis of systemic sclerosis were associated with a higher risk of interstitial lung diseases (ILDs) (odds ratio [OR] = 6.73; P = .048), Raynaud phenomenon (OR = 7.30; P = .034), and malignancy (OR = 350.77; P = .013). The risk of malignancy was also associated with older age (OR 1.31; P = .012), and male patients were associated with a higher risk of fever. For MSAs, anti-aminoacyl-tRNA synthetase antibodies were associated with ILD, antinuclear antibody were associated with a lower risk of arthritis, anti-transcription intermediary factor 1-gamma antibodies were associated with milder symptoms of muscle weakness, anti-Ku antibodies were associated with overlap diagnosis of systemic lupus erythematosus, and anti-Ro52 antibodies were associated with the development of Raynaud phenomenon and Sjögren syndrome.MSAs and overlap diagnosis of systemic sclerosis were significantly associated with clinical phenotypes of DM and PM. Physicians should be vigilant for malignancy in older DM and PM patients with overlap diagnosis of systeic sclerosis. The possibility of developing ILD in patients with overlap diagnosis of systemic sclerosis or serum positivity of anti-aminoacyl-tRNA synthetase antibodies should be considered.

Interleukin-35 in idiopathic inflammatory myopathies.

BACKGROUND: Interleukin-35 (IL-35) is a recently described heterodimeric cytokine that belongs to the IL-12 family and consists of p35 (IL-12a) and EBI3 (IL-27b) subunits. The expression of IL-35 in humans is inducible in response to inflammatory stimuli. Increased IL-35 levels were documented in several autoimmune inflammatory diseases, suggesting a possible immunomodulatory role in their pathogenesis. OBJECTIVES: The aim of this study was to explore a potential role of IL-35 in the pathogenesis of idiopathic inflammatory myopathies (IIM) by studying the expression of IL-35 subunits in muscle biopsy samples and by evaluating serum levels of IL-35 and their association with disease activity in IIM patients. METHODS: The expression of IL-35 subunits was studied in serial sections of 9 muscle biopsy samples [4 polymyositis (PM), 5 dermatomyositis (DM)] and in 7 non-inflammatory control muscle biopsies. Serum levels of IL-35 were measured in 23 PM, 28 DM and 15 cancer associated myositis (CAM) patients as well as in 40 healthy controls. Disease activity was evaluated using the Myositis Disease Activity Assessment Tool (MDAAT) and by serum muscle enzymes. RESULTS: Expression of both IL-35 subunits was evident in the inflammatory infiltrates in IIM muscle biopsies, while no IL-35 expression was observed in control muscle samples. IL-35 serum levels were increased in all IIM patients compared to healthy controls [median 119.5 (range 32.1-1074.5) vs 36.2 (range 1.5-86.5) pg/ml, P < 0.001]. There were no differences in IL-35 serum levels between myositis subgroups (DM, PM or CAM). Serum IL-35 levels correlated significantly with physician's assessment of global (r = 0.29, p = 0.021), muscle (r = 0.30, p = 0.017) and extramuscular (r = 0.30, p = 0.016) disease activity as well as creatine kinase (r = 0.26, p = 0.044) and lactate dehydrogenase (r = 0.40, p = 0.003) levels. There was a significant correlation with pulmonary activity in patients with interstitial lung disease (r = 0.39, p = 0.037). Serum IL-35 correlated negatively with duration of treatment (r = -34, p = 0.009). CONCLUSIONS: IL-35 is overexpressed in inflammatory infiltrates in muscle tissue and serum in IIM patients and there is correlation with several disease activity parameters. These data suggest potential role of locally produced IL-35 in the pathogenesis of inflammatory myopathies.

Reduced miR-146a Promotes REG3A Expression and Macrophage Migration in Polymyositis and Dermatomyositis.

Background: Growing evidence from studies elsewhere have illustrated that microRNAs (miRNAs) play important roles in polymyositis and dermatomyositis (PM/DM). However, little has been reported on their relationship with regenerating islet-derived protein 3-alpha (REG3A) as well as their associative roles in macrophage migration. Therefore, this study sought to establish the association between miR-146a and REG3A as well as investigate their functional roles in macrophage migration and PM/DM pathogenesis. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from PM/DM patients and healthy controls through density centrifugation. Macrophages were obtained from monocytes purified from PBMCs via differentiation before their transfection with miRNA or plasmids to investigate cell migration with transwell assay. An experimental autoimmune myositis murine model was used to investigate PM/DM. Real-time PCR and Western blot analysis were conducted to determine the expression levels of miR-146a, interferon gamma (IFN-γ), interleukin (IL)-17A, and REG3A. Results: The messenger RNA (mRNA) expression level of miR-146a markedly decreased, while the mRNA level of REG3A, IFN-γ, and IL-17A expression increased substantially in PBMCs from PM/DM patients compared with the healthy controls. The levels of IFN-γ and IL-17A in serum from PM/DM patients was much higher than the healthy controls. Immunohistochemistry analysis showed that REG3A expression increased in muscle tissues from patients. Consistent with clinical data, the mRNA expression level of miR-146a also decreased, whereas the mRNA and protein level of REG3A, IFN-γ, and IL-17A significantly increased in the muscle tissues of experimental autoimmune myositis mice. Moreover, miR-146a inhibited monocyte-derived macrophage migration, and REG3A promoted macrophage migration. In addition, IL-17A induced REG3A expression, while miR146a inhibited expression of REG3A in monocyte-derived macrophages from the PBMCs of the healthy donors. Notably, inhibition of macrophage migration by miR-146a was via the reduction in REG3A expression. Conclusions: Reduced miR-146a expression in PM/DM leads to increased REG3A expression that increases inflammatory macrophage migration, which may be a possible underlying mechanism of DM/PM pathogenesis.

Coexistencia de anticuerpos anti-histidil-tRNA-sintetasa y anti-partícula de reconocimiento de la señal en un paciente con polimiositis / Coexistence of anti-Jo1 and anti-signal recognition particle antibodies in a polymyositis patient

Las miopatías inflamatorias idiopáticas son un grupo heterogéneo de miopatías potencialmente tratables. Se clasifican en 4 subtipos: dermatomiositis, polimiositis, miositis autoinmune necrosante y miositis por cuerpos de inclusión, en función de las características clínicas e histológicas. Los anticuerpos asociados a miositis y los autoanticuerpos específicos de miositis se encuentran frecuentemente en pacientes con miopatías inflamatorias, siendo útiles en el diagnóstico y clasificación. El anticuerpo anti-histidil tRNA sintetasa es el más prevalente y el más específico para polimiositis. El anticuerpo de partícula de reconocimiento de señal es también un autoanticuerpo especıfico para polimiositis, pero más infrecuente, y raramente se encuentra en pacientes que presentan otros autoanticuerpos específicos para miositis. En este trabajo se presenta un paciente con polimiositis en el que coexisten los 2 autoanticuerpos en el suero, lo que se considera una situación clínica extremadamente rara. Aquí analizamos la evolución clínica y hallazgos para examinar el efecto de la coexistencia y la posible interacción sobre el pronóstico

Idiopathic inflammatory myopathies are a heterogeneous group of potentially treatable myopathies. They are classified, on the basis of clinical and histopathological features, into four subtypes: dermatomyositis, polymyositis, necrotizing autoimmune myositis and inclusion-body myositis. Myositis-associated antibodies and myositis-specific autoantibodies are frequently found in patients with idiopathic inflammatory myopathies, and are useful in the diagnosis and classification. Anti-histidyl transfer RNA synthetase antibody is the most widely prevalent and is highly specific for polymyositis. Signal recognition particle antibody is also a specific autoantibody for polymyositis, but it is infrequent and rarely found in patients having other myositis-specific autoantibodies. We present a man with polymyositis who had both antibodies in serum, which is considered an extremely rare clinical situation. Here we analyze the clinical course and findings, and examine the effect of the coexistence and possible interaction on prognosis

Absolute reduction of regulatory T cells and regulatory effect of short-term and low-dose IL-2 in polymyositis or dermatomyositis.

AIM: The study aimed to investigate the changes in peripherallymphocyte and CD4+T subsets and to observe the regulatory effect of low-dose interleukin-2 (ld-IL2) on these cells in polymyositis or dermatomyositis (PM/DM). METHODS: Lymphocyte subsets (CD3+T, CD4+T, CD8+T, B and natural killer (NK) cells), CD4+T subsets (Th1, Th2, Th17 and regulatory T (Treg) cells) and multiple cytokines of 71 patients after admission and treatment were measured by flow cytometry, as well as these indicators in 30 healthy controls (HCs). In DM, 35 cases were administrated with ld-IL2 combined with conventional therapy, the remaining 26 patients received conventional therapy only. RESULTS: The numbers of CD3+T and CD4+T cells in PM/DM were markedly decreased. Meanwhile, the absolute number and percentage of peripheral Treg cells in PM/DM, as well as Th1 cells in DM, were significantly lower than those in HCs (P < 0.05), but Th2 and Th17 cells had no significant difference. The ratio of Th17/Treg in PM (P = 0.031) and in DM (P = 0.003) were obviously higher than that in HCs. The deficiency of Treg cells was associated with the occurrence of interstitial lung disease (ILD) in myositis patients. Meanwhile, reduced production of IL-2 was also observed in PM/DM (P < 0.001). ld-IL2 combination therapy could significantly increase the numbers of CD4+T subsets in DM, especially Treg cells (expanded 2.5 times). CONCLUSIONS: The decline of peripheral Treg cells and serum IL-2 were found in PM/DM. ld-IL2 combination therapy could significantly increase the number of Treg cells.

A case of overlap syndrome (scleroderma and polymyositis) associated with the development of sudden chest pain due to myocardial damage.

Myocardial injury with systemic sclerosis (SSc) causes pericarditis and arrhythmia, and polymyositis-induced muscle inflammation causes myocarditis. We report a rare case of overlap syndrome (SSc and polymyositis) who presented with sudden chest pain secondary to myocardial fibrosis. Although the etiology of chest symptoms in collagen disease was difficult to identify, cardiac magnetic resonance imaging (MRI) revealed not myocarditis but myocardial fibrosis in our case. Synthetic judgement of serum brain natriuretic peptide/ troponin T levels and cardiac MRI is useful in the search for the cause of chest symptoms even in patients with collagen diseases.

Interleukin-35: A Serological Biomarker for Patients with Polymyositis/Dermatomyositis.

Interleukin (IL)-35 is confirmed as an important modulator in immune response. The aim of the study was to explore the role of IL-35 in the development of polymyositis/dermatomyositis (PM/DM). Ninety-five patients with PM/DM and 30 healthy controls (HCs) were recruited. Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Paque Plus density gradient centrifugation. Protein IL-35, IL-17, and tumor necrosis factor (TNF)-α levels were measured using enzyme-linked immunosorbent assay method. The IL-35 serum levels in PM/DM patients were significantly higher than those in HCs and were correlated with PM/DM-related features: disease activity, muscle damage, and interstitial lung disease (ILD). Exogenous IL-35 notably suppressed lipopolysaccharide-induced IL-17 and TNF-α production in PBMCs of patients with PM/DM. Elevated serum IL-35 levels could act as a disease activity biomarker and an indicator of ILD in PM/DM. IL-35 may play an anti-inflammatory role in PM/DM.

Can hyperuricemia predict glycogen storage disease (McArdle's disease) in rheumatology practice? (Myogenic hyperuricemia).

Gout disease is an inflammatory arthritis that arises due to the accumulation of monosodium urate crystals (MSU) around the joints and in tissues. Clinical manifestation of metabolic diseases leading to secondary hyperuricemia most predominantly occurs in the form of gouty arthritis. Hyperuricemia and gout may develop during the course of glycogen storage diseases (GSD), particularly in GSD type I, which involves the liver. On the other hand, during the course of GSD type V (GSDV, McArdle's disease), which merely affects the muscle tissue due to the deficiency of the enzyme myophosphorylase, hyperuricemia and/or gout is rarely an expected symptom. These patients may mistakenly be diagnosed as having idiopathic hyperuricemia and associated gout, leading to the underlying secondary causes be overlooked and thus, diagnostic delays may occur. In this case report, we present a premenopausal female patient who experienced flare-ups of chronic arthritis while on disease-modifying antirheumatic drugs and intraarticular steroids due to a diagnosis of undifferentiated arthritis. The patient was initially suspected of having gouty arthritis because elevated concentrations of uric acid were incidentally detected, but then, a diagnosis of asymptomatic GSDV was made owing to elevated concentrations of muscle enzymes during colchicine use. Our aims were to remind rheumatologists of the phenomenon of "myogenic hyperuricemia" and to discuss the potential causes of hyperuricemia that develop during GSD along with the available literature.

Clinical significance of myositis-specific autoantibody profiles in Japanese patients with polymyositis/dermatomyositis.

Myositis-specific autoantibodies, such as anti-melanoma differentiation associated gene 5 (MDA5) and anti-anti-amino acyl-tRNA synthetases (ARS) antibodies, are associated with interstitial lung diseases (ILD), which determine the prognosis of polymyositis/dermatomyositis (PM/DM) patients. However, there is a paucity of data on the clinical correlation between anti-Sjögren syndrome-related antigen A (anti-SSA)/Ro52 antibodies in PM/DM. We investigated the prevalence of myositis-specific autoantibodies including anti-SSA/Ro52 antibody and assessed the clinical significance of these antibodies in patients with PM/DM.We retrospectively reviewed demographic data and clinical outcomes in patients with PM/DM. The study population comprised 24 patients with PM and 60 patients with DM. The presence of anti-myositis-specific antibodies (MDA5, ARS, Jo-1, SSA/Ro52) was determined by immunosorbent assay (ELISA).Anti-MDA5 antibody was detected in 18 patients with DM (n = 60). Anti-ARS/anti-SSA/Ro52 antibodies were detected in 31 and 39 patients with PM/DM (n = 84). Rapidly progressive ILD patients were mainly found in the anti-MDA5 antibody-positive DM group. During the follow-up period, 9 patients died. Kaplan-Meier analysis demonstrated that survival rates seem to be lower in DM patients with anti-MDA5 antibodies compared with those without anti-MDA5 antibodies. Furthermore, dual positivity for anti-SSA/Ro52 and anti-MDA5 antibodies was significantly higher in nonsurviving DM patients compared with survivors.Although the presence of anti-ARS or anti-MDA5 antibodies is a prognostic marker in patients with PM/DM, combined presence of anti-SSA/Ro52 and anti-MDA5 antibodies represent another marker for clinical outcome in DM patients. Our results suggest that anti-SSA/Ro52 antibody positivity in DM patients with anti-MDA5 antibody reveals a subgroup of DM patients with poor prognosis.

Serum C1q Concentration Positively Correlates with Erythrocyte Sedimentation Rate in Polymyositis/Dermatomyositis.

C1q is an important component of the classical complement pathway. This study aimed to investigate C1q concentrations in the sera of PM/DM patients. C1q concentrations were measured in the sera of 87 PM/DM patients and 100 healthy subjects. In addition, the association between C1q concentration and laboratory indexes such as CK, AST, ALT, LDH, hsCRP, and ESR were also evaluated. Our data indicated no significant difference in the serum C1q concentration between PM/DM patients and healthy subjects. However, serum C1q concentrations were observed to be significantly higher in PM/DM patients in patients group with elevated ESR than in those with normal ESR (207.55±37.54 mg/L and 180.69±38.90 mg/L, respectively; P=0.008). Furthermore, there was a positive correlation between serum C1q concentration and ESR (P=0.002), but no association was observed with CK, AST, ALT, LDH, and hsCRP levels. This study demonstrated C1q levels were elevated in PM/DM patients with higher ESR and revealed significant positive correlation. However, the exact role of the classical complement pathway in PM/DM needs further elucidation.

Serum KL-6 is associated with the severity of interstitial lung disease in Chinese patients with polymyositis and dermatomyositis.

OBJECTIVE: This cross-sectional study was designed to assess the clinical significance of the serum KL-6 in the diagnosis of interstitial lung disease (ILD) in patients with idiopathic inflammatory myopathy (IIM). METHODS: We measured serum KL-6 levels in 184 patients with IIM using a chemiluminescent enzyme immunoassay and compared KL-6 levels between patients with and without ILD, according to other clinical features. RESULTS: IIM patients with ILD had significantly higher serum KL-6 levels than those without ILD (776.5 [372.3-1378.8] vs. 297.5 [204.75-599.3] U/ml, P < 0.001). At a cut-off of 461.5 U/ml identified by ROC curve, serum KL-6 yielded a sensitivity of 70.2% and specificity of 73.9% for ILD in IIM patients. IIM patients with an elevated serum KL-6 were more likely to have clinical symptoms of mechanic's hands (P = 0.002), anti-Jo-1 antibody positivity (P = 0.021), dysphagia (P = 0.039), hoarseness (P < 0.001), and polyarthritis/polyarthralgia (P < 0.001). Significant inverse correlations were found between serum KL-6 levels and pulmonary function tests (P < 0.01), including forced vital capacity (FVC, %Pred), total lung capacity (TLC, %Pred), and diffusing capacity for carbon monoxide (DLCO, %Pred). CONCLUSIONS: Serum KL-6 offers high sensitivity and specificity for the diagnosis of IIM-associated ILD and is inversely correlated with pulmonary function deterioration. Serum KL-6 may represent a promising biomarker for monitoring ILD severity in IIM patients.

Detection of serum MCP-1 and TGF-ß1 in polymyositis/dermatomyositis patients and its significance.

OBJECTIVE: This study aims to detect serum levels of monocyte chemoattractant protein-1 (MPC-1) and transforming growth factor-ß1 (TGF-ß1) in polymyositis/dermatomyositis (PM/DM) patients complicated with interstitial lung disease (ILD), to reveal the significance of the changes in these levels in the pathogenesis of PM/DM complicated with ILD. METHODS: Serum MCP-1 and TGF-ß1 levels in PM/DM patients complicated with ILD, patients with pulmonary infections and normal controls (n = 30, each) were detected using enzyme-linked immunosorbent assay (ELISA), and the correlation between PM/DM complicated with ILD and serum MCP-1 and TGF-ß1 levels was analyzed. RESULTS: Serum MCP-1 and TGF-ß1 levels were both higher in PM/DM patients complicated with ILD compared with patients with pulmonary infections and normal controls. CONCLUSION: Serum MCP-1 and TGF-ß1 levels increased in PM/DM patients, and were closely correlated to the complication of ILD. This finding can be used for distinguishing between pulmonary infections and ILD, providing a new diagnostic method for the early prediction of DM/PM complicated with ILD.

Diffusion-weighted magnetic resonance imaging is useful for assessing inflammatory myopathies.

INTRODUCTION: Short tau inversion recovery (STIR) sequences in whole-body MRI are usually used for detecting muscle edema (ME) in inflammatory myopathies. We evaluated b-value 800 diffusion-weighted imaging (b800 DWI). METHODS: Two radiologists independently and a consensus reader retrospectively reexamined 60 patients with inflammatory myopathies and 15 controls. For each participant, 78 muscles were analyzed with 3 sets of imaging acquisitions: T1-weighted (T1) turbo spin echo and STIR; T1 and DWI; and T1, STIR and DWI. Mean edema per patient was compared between sequences. Agreement was evaluated. RESULTS: Diffusion-weighted imaging detected more ME compared with STIR (P < 0.001). Agreement between readers was better with both sequences (k = 0.94) than with b800 DWI (k = 0.89) or STIR (k = 0.84) alone. DISCUSSION: Diffusion-weighted imaging is a valuable add-on for the study of inflammatory myopathies. Muscle Nerve 59:555-555, 2019.

Serum-soluble TRAIL: a potential biomarker for disease activity in myositis patients.

OBJECTIVES: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the TNF super-family, which is involved in the regulation of immune response and pathogenesis of autoimmune diseases, including polymyositis (PM) and dermatomyositis (DM). In this study, we examined the level and origin of serum-soluble TRAIL (sTRAIL) in patients with PM and DM and analyzed its association with disease activity and clinical features. METHOD: 11 PM patients, 33 DM patients, and 20 healthy controls were enrolled in this study. Clinical features were recorded when admitted, and disease activity was evaluated by myositis disease activity assessment visual analogue scale (MYOACT). TRAIL expression in muscle tissues was detected by immunohistochemistry. Serum sTRAIL levels were measured by enzyme-linked immunosorbent assay. The expression of membrane TRAIL (mTRAIL) and its receptors, including DR4 and DR5, on circulating T cells was analyzed by flow cytometry. RESULTS: TRAIL was expressed in infiltrated inflammatory cells in muscle tissues from patients. The serum sTRAIL level was markedly increased in patients and was positively correlated with the disease activity. Serum sTRAIL was decreased after therapy in patients and was specifically higher in patients with dysphagia, but lower in patients with autoantibody Jo-1 positive. The frequency of mTRAIL and its receptors on circulating T cells from patients were significantly elevated than that from healthy controls. CONCLUSIONS: The serum sTRAIL could be a biomarker for evaluating the disease activity of PM and DM, and targeting the generation of TRAIL in T cells might be a potential approach in the treatment of PM and DM.

Serum interleukin-17A level is associated with disease activity of adult patients with dermatomyositis and polymyositis.

OBJECTIVES: To assess serum interleukin (IL)-17A levels in patients with dermatomyositis (DM) and polymyositis (PM) and correlate them with the demographic, clinical, laboratory and therapeutic data of these diseases. METHODS: This was a cross-sectional, single-centre study that included defined DM and PM patients who were age-, gender- and ethnicity-matched to healthy individuals. Serum IL-17A analysis, as well as analysis for other cytokines (IL-6, TNFα and IFNγ), was performed by multiplex immunoassay. The disease status parameters were based on the International Myositis Assessment and Clinical Studies Group (IMACS) set scores. RESULTS: Eighty DM, 32 PM patients and 104 healthy individuals were enrolled. Mean age of patients with DM and PM was 46.0 and 47.7, respectively, with a predominance of women and white ethnicity in both groups. Overall, clinical, laboratory, therapeutic, and current disease status were similar among patients with DM and PM. Median serum IL-17A level was higher in patients with PM and DM than the control group (0.73 vs. 0.49 vs. 0.35 pg/mL, respectively; p<0.050) and higher in PM when compared to DM (p<0.001). In DM, serum IL-17A levels were associated with cumulative cutaneous lesions, IMACS parameters, and serum IL-6 and IFNγ levels. In PM, serum IL-17A levels correlated with patients' current age, IMACS parameters and serum TNFα and IFNγ levels. CONCLUSIONS: Serum IL-17A levels are not only increased, but also associated with disease activity in patients with DM and PM. Our data strongly suggest that IL-17A may be a biomarker of disease activity for these systemic autoimmune myopathies.

Coexistence of anti-Jo1 and anti-signal recognition particle antibodies in a polymyositis patient. / Coexistencia de anticuerpos anti-histidil-tRNA-sintetasa y anti-partícula de reconocimiento de la señal en un paciente con polimiositis.

Idiopathic inflammatory myopathies are a heterogeneous group of potentially treatable myopathies. They are classified, on the basis of clinical and histopathological features, into four subtypes: dermatomyositis, polymyositis, necrotizing autoimmune myositis and inclusion-body myositis. Myositis-associated antibodies and myositis-specific autoantibodies are frequently found in patients with idiopathic inflammatory myopathies, and are useful in the diagnosis and classification. Anti-histidyl transfer RNA synthetase antibody is the most widely prevalent and is highly specific for polymyositis. Signal recognition particle antibody is also a specific autoantibody for polymyositis, but it is infrequent and rarely found in patients having other myositis-specific autoantibodies. We present a man with polymyositis who had both antibodies in serum, which is considered an extremely rare clinical situation. Here we analyze the clinical course and findings, and examine the effect of the coexistence and possible interaction on prognosis.

Elevated serum YKL-40 correlates with clinical characteristics in patients with polymyositis or dermatomyositis.

BACKGROUND: Serum YKL-40 has been proved to be a promising biomarker for estimating the disease activity of several autoimmune diseases. However, its utility in polymyositis or dermatomyositis has not been established. The aim of this study was to investigate the utility of YKL-40 in patients with polymyositis/dermatomyositis. METHOD: Patients with definite polymyositis/dermatomyositis who visited the Second People's Hospital of Wuxi between April 2016 and March 2017 were prospectively enrolled. Eighty-seven healthy individuals were set as a control. Serum YKL-40 of all participants was determined using ELISA. The associations between YKL-40 and clinical characteristics of polymyositis/dermatomyositis were analysed using the Student's t-test, Mann-Whitney test and receiver operating characteristic curve analysis. RESULTS: A total of 99 patients with polymyositis/dermatomyositis were enrolled. The patients with polymyositis/dermatomyositis had significantly higher serum YKL-40 concentration. Patients with interstitial lung disease had significantly higher YKL-40 concentration than those without. Serum YKL-40 was positively correlated with myositis disease activity assessment visual analogue scale, C-reactive protein, erythrocyte sedimentation rate and ferritin. The area under receiver operating characteristic curve of YKL-40 for identifying interstitial lung disease was 0.82. CONCLUSIONS: Serum YKL-40 is a useful biomarker for estimating disease activity or severity of polymyositis/dermatomyositis.

Effect of CTLA4-Ig (abatacept) treatment on T cells and B cells in peripheral blood of patients with polymyositis and dermatomyositis.

We aimed to evaluate in vivo effects of abatacept on phenotypes of T and B cells in the circulation of myositis patients in a sub-study of the ARTEMIS trial. Twelve patients with paired frozen PBMCs before and after 6-month abatacept treatment were included in this sub-study where mass cytometry (CyTOF) was chosen as a technology to be tested for its utility in a real-life clinical immune monitoring setting. Using CyTOF, the peripheral T cell phenotypes demonstrated considerable variation over time and between individuals precluding the identification of treatment-specific changes. We therefore conclude that studies of patient cohorts displaying wide clinical heterogeneity using mass cytometry must be relatively large in order to be suited for discovery research and immune monitoring. Still, we did find some correlations with functional muscle outcome, namely positive correlations between the ratio of CD4+ T cells and CD8+ T cells (CD4/CD8) in peripheral blood samples both at baseline and after treatment with muscle endurance improvement as assessed by the functional index-2 (FI-2) test. Our data suggest that the CD4/CD8 ratio in circulation at time of active disease may be a predictor of treatment efficacy in myositis patients.