Disease specific signature of circulating miR-150-5p and miR-21-5p in myasthenia gravis patients

PURPOSE Reliable biological markers for patients with the autoimmune neuromuscular disorder myasthenia gravis (MG) are lacking. We determined whether levels of the circulating immuno-microRNAs miR-150-5p and miR-21-5p were elevated in sera from clinically heterogeneous MG patients, with and without immunosuppression, as compared to healthy controls and patients with other autoimmune disorders. METHODS Sera from 71 MG patients and 55 healthy controls (HC) were analyzed for the expression levels of miR-150-5p and miR-21-5p with qRT-PCR. Sera were also assayed from 23 patients with other autoimmune disorders (AID; psoriasis, Addison's and Crohn's diseases). RESULTS 34 MG patients had no immunosuppressive drug treatment (MG-0) and 37 patients were under stable immunosuppressive drug treatment since ≥ 6 months (MG+IMM). Serum levels of miR-150-5p and miR-21-5p were higher in the MG-0 patients compared to HC (p<0.0001). Further, miR-150-5p levels were 41% lower and miR-21-5p levels were 25% lower in the MG+IMM compared to MG-0 (p=0.0051 and 0.0419). In the AID patients, mean miR-150-5p and miR-21-5p were comparable with healthy controls (p=0.66). CONCLUSIONS The immuno-microRNAs miR-150-5p and miR-21-5p show a disease specific signature, which suggests these microRNAs as possible biological autoimmune markers of MG.