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Objective: To investigate the clinical significance of detection of myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) in patients with connective tissue disease-associated interstitial lung diseases (CTD-ILD). Methods: Serum samples of 120 patients with CTD-ILD admitted to the Department of Respiratory, Affiliated Drum Tower Hospital of Nanjing University Medical College from December 2016 to April 2018 were collected for analysis. The patients included 45 with polymyositis/dermatomyositis (PM/DM), 36 with Sjogren's syndrome (SS) and 39 with undifferentiated connective tissue disease (UCTD). There were 37 males and 83 females with an average age of (56±11) years. Thirty-two patients with non-CTD-ILD, 10 males and 22 females with an average age of (42±17) years, were enrolled as the control group. Euroline Autoimmune Inflammatory Myopathies 16 Ag kit was used for detecting MSAs and MAAs, and the positive rates of serum MSAs and MAAs were calculated. The antibody distribution and clinical characteristics of different groups were analyzed and compared. Results: Eighty-nine of the 120 patients with CTD-ILD were positive for MSA and/or MAA (74.2%), and the detection rates of MSAs and MAAs were 52.5% (63/120) and 61.7% (74/120) respectively. No myositis antibody was detected in the non-CTD-ILD group. The detection rates of MSAs in PM/DM-ILD group, SS-ILD group and UCTD-ILD group were 75.6% (34/45), 33.3%(12/36) and 43.6%(17/39) respectively. The total detection rate of MSAs in PM/DM group was significantly higher than that in SS group and UCTD group (χ(2)=14.53, 8.95, 0.01). The anti-ARS was the most frequent (50/120, 41.7%). The positive rates of MAAs in the three groups were 64.4%(29/45), 77.8%(28/36), 43.6%(17/39) respectively, and anti-Ro-52 accounted for 60%(72/120), and were highly correlated with MSAs such as anti-Jo-1 antibodies. Conclusion: Myositis antibody profiling should be performed in patients with ILD who were negative for conventional autoimmune antibody testing and had no CTD. In patients with SS-ILD and UCTD-ILD, the myositis antibody spectrum could detect the presence of myositis-specific antibodies and myositis-related antibodies in some patients, and its role in clinical diagnosis and treatment needed further observation.

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.

Background: Little is known so far on the lipid profile in polymyositis (PM) patients. Our aim is to identify lipid profiles in untreated patients with early PM, to assess the association between lipid profiles and C-reactive protein (a sensitive marker of inflammation) in these patients., Methods and Findings: This work was conducted as a case-control study. Sixty untreated patients with PM and 60 age- and sex-matched healthy controls were included. The duration of PM was less than six months, and none of them had received intermittent or regular corticosteroids or disease-modifying antirheumatic drugs or biological agents prior to the study. Triglyceride (TG), total cholesterol (TC), LDL-cholesterol (LDL-C), and HDL-cholesterol (HDL-C), and C-reactive protein (CRP) were assessed using standard techniques. Thirty patients (50%) had a decreased level of HDL-C and 47% had an increased level of TG. The levels of HDL-C, LDL-C, and TC in PM were significantly lower than in controls (P<0.001, P<0.01, P<0.001, respectively). The level of TG was significantly higher in PM than in controls (P<0.001). The level of very low LDL-cholesterol (VLDL-C), and the ratios of VLDL-C/LDL-C, TC/HDL-C, and LDL-C/HDL-C were significantly higher than in controls (all P<0.001). Serum CRP levels correlated negatively with HDL-C (r = -0.352, P = 0.006) and TC (r = -0.262, P = 0.043). After adjustment for age, gender, smoking, drinking, body mass index, and pulmonary fibrosis/infection, linear regression model demonstrated that CRP is associated with HDL-C among PM patients (P = 0.028)., Conclusions: Dyslipidemia is a common feature in patients with PM that is characterized by a decrease in HDL-C and an increase in TG, suggesting a high risk of atherosclerosis. The Inflammatory condition in PM may account for the metabolism of HDL-C.