MicroRNAs (miRNAs) are short non-coding RNA involved in the regulation of multiple biological pathways. By post-transcriptionally repressing the expression of protein-encoding genes they play key functions in the regulation of almost every cellular processes. Altered expression of miRNAs has been described in many diseases, including immune-mediated inflammatory disorders (IMIDs) such as arthritis or lupus. Because of their specificity and stability, as well as their detectable presence in many body fluids, miRNAs have been proposed as diagnostic and prognosis biomarkers for precision medicine in many diseases.
In the past, our team has shown that it is possible to measure miRNA expression in whole blood or serum to diagnose different rheumatisms and to predict clinical response to therapy. As such, we identified circulating miR-125b as a potential biomarker predicting response to rituximab in rheumatoid arthritis, and described a miRNAs-based signature in serum that can predict severe renal features in patients with lupus.
Recently, using a comparative approach with the synovial fluid of inflamed joints and serum of children with inflammatory and infectious arthritis, we have identified a specific miRNA-based signature and associated signaling pathways, which could be useful for diagnosis, classification and monitoring of juvenile idiopathic arthritis. They can also help us understanding better the pathophysiology of this very heterogenous group of juvenile rheumatisms. Overall, circulating miRNAs can serve as non-invasive biomarkers for human IMIDs diseases, and help building a personal medicine for optimized care of patients.