Metabolomic Analysis of Serum Reveals a Unique Metabolomic Profile in Patients With Myositis and Identified Several Potential Biomarkers in Polymyositis Versus Dermatomyositis Patients

DM and PM were the two major subtypes in myositis; among which, a unique metabolomic and biomarker profile remains lacking. Serum from 36 diagnosed myositis patients (28 DM and 8 PM) and 29 healthy controls was analyzed using HPLC-Q-TOF-MS/MS. PLS-DA was conducted through MetaboAnalyst 5.0 to identify the differential metabolites. The KEGG analysis was utilized to observe the related metabolic pathways. The potential biomarker value was assessed using ROC analysis. The relationship between the clinical characteristics and the levels of identified differential metabolites was analyzed using R language. PLS-DA showed a clear separation between healthy controls and myositis patients, and 131 differential metabolites were identified. KEGG analysis uncovered multiple disturbed metabolic pathways. Besides, nine differential metabolites were identified between PM and DM patients, which were involved in pentose and glucuronate interconversions. ROC curve analysis revealed the AUC of these identified metabolites is above 0.7. Among them, indoxyl sulfate, oleamide, and palmitoylethanolamide presented moderate or strong correlation with clinical characteristics. Metabolomics presents a different spectrum between myositis patients and healthy controls, PM and DM patients. Besides, indoxyl sulfate, oleamide, and palmitoylethanolamide may be potential biomarkers in distinguishing PM from DM.