Utility of circulating serum miRNA profiles to evaluate the potential risk and severity of immune-mediated inflammatory disorders.

Immune-mediated inflammatory disorders (IMID) are a group of diseases that present inflammation as a major pathogenic mechanism. They affect 15% of the population and pose a heavy socio-economic burden. Despite the growing knowledge on the etiopathogenesis of these diseases and the marked improvement in their management, there is a lack of predictive markers of IMID development or severity suitable for early diagnosis and adjustment of treatment intensity. The possibility that certain circulating miRNA profiles could be used as biomarkers of risk of development and/or severity of several autoimmune diseases has fuelled the interest in using them to improve the selection of successful treatments. The multi-pronged approach proposed here sought to reveal circulating miRNAs and miRNA signatures that could act as new predictive biomarkers of IMID development and severity. Our results showed that the circulating levels of miR-19b and miR-26b were significantly decreased (p < 0.001) in IMID patients compared to controls. Furthermore, receiver operating characteristic (ROC) curve analysis showed that these miRNAs were suitable discriminators capable to identify an IMID, with areas under the curve (AUC) of 0.85 and 0.83, respectively. In addition, we established that miR-19a and miR-143 were significantly increased in IMID patients with severe disease (p < 0.05). In summary, our findings identify two different miRNA signatures. One of them is associated with the presence of IMIDs and could lead to the development of tools for their early detection. The second signature is able to discriminate between mild and severe forms of these disorders and could be a putative tool to select patient candidates for a more intense treatment.