| Objective(1) To screen for and validate microRNA(miRNA) markers in peripheral blood mononuclear cells(PBMC) of polymositis(PM) and dermatomyositis(DM) patients;(2)To analyze the prevalence of myositis associated antibodies (MAAs) and myositis specific antibodies (MSAs) and their clinical relevance;(3)To evaluate the risk factors of PM/DM hospital mortality.Methods(1)The PBMC of untreated PM/DM patients and health controls (HC) were screened for miRNA expression profile by miRNA Array. Bioinformatics analysis were done to predict the target genes of differentially expressed miRNAs and to analyse relevant pathways. miRNAs closely related to the pathogenesis of PM/DM were chosen to do real-time PCR validation in a larger cohort of patients and HC. For the validated miRNAs, their clinical relevance was also analyzed. The target gene of validated miRNA was predicted by online software and real-time PCR was done to evaluate its expression level in PBMC of PM/DM patients. (2)The clinical data, MSAs and MAAs of 228 PM/DM patients were retrospectively collected from PUMCH inpatient and outpatient case records. The prevalence of each antibody was investigated. Patients were grouped by their antibody status (positive or negative), and clinical relevance was analyzed for each antibody. (3)The case records of 45 PM/DM patients who died in hospital and 90 patients who survived hospital stay were reviewed; binary logistic regression was done to find the independent risk factors for hospital mortality of PM/DM patients.Results(1) miRNA array screen was done in 6 untreated PM/DM patients and 3 HC,38 differentially expressed miRNAs were detected, which included 24 up-regulated and 14 down-regulated miRNAs. Considering the expression level and results from bioinformatics analysis,4 miRNAs were chosen for real-time PCR validation: hsa-miR-320a, hsa-miR-335-3p, hsa-miR-34a-5p, and hsa-miR-454-3p. After PCR validation in 34 PM/DM patients and 20HC, while hsa-miR-320a, hsa-miR-335-3p and hsa-miR-454-3p were not significantly differentially expressed in PM/DM, hsa-miR-34a-5p was proved to be significantly up-regulated, the relative quantity (RQ) was 3.20 (1.87,9.24) vs.1.68±0.91, P=0.001. In subgroup analysis, hsa-miR-34a-5p was significantly up-regulated in DM group,ILD group, and DM-ILD group compared to PM group, non-ILD group, and DM-nonILDgroup. The RQs were 4.81(2.39,10.92) vs. 1.45±0.89,P=0.001; 5.85 (2.66,13.22)vs.1.94(1.36,3.13), P=0.001; 6.32(3.11,13.32) vs.3.66±2.88, P=0.012; respectively. Expression level of SIRT1, the target gene of hsa-miR-34a-5p, was also evaluated by real-time PCR, and the mRNA level of SIRT1 was significantly down-regulated in PBMC of PM/DM patients compared to HCs(RQ 0.73±0.37 vs.1.23±0.38,P<0.001).(2)Multiple auto-antibodies can be detected in the serum of DM/PM patients. Anti-Jo-1 antibody was the most prevalent MSA, with a positive rate of 13%(30/224), and anti-Jo-1 positive group had higher incidence of fever, mechanician hands, and ILD (57%vs.37%,37%vs.20%,93% vs.66%, respectively, P< 0.05). The positive rate of anti-Mi-2 antibody was 7.2%(5/69) in DM patients. The positive rate of anti-SRP, anti-PL-7, and anti-PL-12 antibody was 7.5%(4/53),2.2%(2/91),2.2%(2/91), respectively. No positive anti-EJ or anti-OJ antibody was found in 54 patients who had tested these antibodies. Anti-Ro52 antibody was the most prevalent MAA, with a positive rate of 48%(85/177), and anti-Ro52 positive group had a significantly higher incidence of Gottron’s sign, fever, arthralgia/ arthritis, and ILD (58%vs.41%,50%vs.27%, 49%vs.29%,88%vs.54%, respectively, P< 0.05). The positive rate of anti-SSA, anti-PM-Scl and anti-Ku antibody was 14%(31/215),2.4%(4/169) and 1.1%(1/91), respectively. Anti-SSB (1.9%,4/214), anti-RNP (2.3%,5/215), and anti-AMA-M2 (4.8%, 8/166) antibody were significantly related to cardiac involvement, patients with positive antibodies had higher incidence of cardiac involvement (50%vs.7.2%,40%vs.4.8%, 50%vs.3.8%, respectively, P< 0.05). Anti-RNP antibody positive patients also had higher incidence of pulmonary hypertension (60%vs.7.6%, P=0.001).(3)The leading cause of PM/DM patients’hospital mortality were pulmonary infection (44%), progress of ILD (18%), and progress of ILD complicated with pulmonary infection (20%). Logistic regression analysis identified 4 independent risk factors related to hospital mortality:pulmonary infection (OR187.2,95%CI25.8-1356.4,P <0.001), cardiac involvement (OR35.0,95%CI1.2-1054.9,P=0.041), Gottron’s sign (OR13.2,95%CI2.6-67.0, P=0.002), and rapid erythrocyte sedimentation rate (OR9.9, 95%CI2.0-49.0, P=0.005).Conclusion(1)There were differentially expressed miRNAs in PBMC of PM/DM patients, among those hsa-miR-34a-5p was signifaicantly up-regutalted and was related to ILD, its target gene SIRT1 was siganificantly down-regulated. hsa-miR-34a-5p may have paticipated in the pathogenesis of ILD associated with PM/DM, and may be a new-serum biomarker of PM/DM. (2)There were multiple auto-antibodies in the serum of PM/DM patients, and these antibodies had different clinical relavance. Auto-antibodyies played an important role in the management of PM/DM pathients.(3) PM/DM were debilitating inflammatory myopathies with high hospital mortality, pumonary infection, cardiac invlovement, Gottron’s sign, and rapid ESR were independent predictive factors for inpatient death. |
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