Small extracellular vesicle microRNAs in pediatric myasthenia gravis plasma and skeletal muscle

Background The diagnosis of myasthenia gravis (MG) in children remains difficult. Circulating small extracellular vesicle (sEV)-derived miRNAs (sEV-miRNAs) have been recognized as biomarkers of various diseases and can be excreted by different cell types. These biomarker candidates also play a vital role in autoimmune diseases via intercellular communication.Methods In the present study, we used sEV isolation and purification methods to extract the plasma-derived sEV-miRNAs from children with MG and healthy controls. A small RNA sequencing analysis confirmed the miRNA expression features in plasma-derived sEVs from MG patients. The miRNA expression analysis in vitro was determined using microarray analysis. The enrichment and network analyses of altered sEV-miRNAs were performed using miRNA databases and Database for Annotation, Visualization, and Integrated Discovery website. Quantitative real-time polymerase chain reaction was performed for validation of sEV-miRNA. The diagnostic power of altered sEV-miRNAs was evaluated using receiver operating characteristic curve analyses.Results Twenty-four sEV-miRNAs with altered expression level were identified between groups by DESeq2 method. The miRNAs were extracted from the sEVs, which were isolated from human primary skeletal muscle cell culture treated with mAb198. The target genes and enriched pathways of sEV-miRNAs partially overlapped between cell supernatant and plasma samples. The significantly downregulated miR-143-3p was validated in quantitative real-time polymerase chain reaction analysis.Conclusions For the first time, we report that plasma-derived sEV-miRNAs may act as novel circulating biomarkers and therapeutic targets in pediatric MG. What is already known on this subject: The miRNA expression signature can potentially be used as a biomarker to diagnose a wide variety of diseases. Small extracellular vesicles (sEVs) can provide a stable environment for miRNA cargo to avoid degradation. What this study adds: Twenty-four sEV-miRNA candidates were differentially expressed in pediatric myasthenia gravis (MG) patients compared to healthy controls. Plasma-derived sEV-miR-143-3p has potential value in the diagnosis of pediatric autoantibody seronegative myasthenia gravis. How this study might affect research, practice, or policy: Our findings provide a set of plasma-derived sEV-miRNAs candidates for the diagnosis of pediatric myasthenia gravis, especially autoantibody seronegative patients.