Critical roles of microRNAs in the pathogenesis of systemic sclerosis: New advances, challenges and potential directions.

Systemic sclerosis (SSc) is an autoimmune disease characterized by immune disorders, vascular obliteration, excessive extracellular matrix deposition, skin fibrosis, and further pathological change of internal organs. To date, the exact etiology of this complicated disease remains unknown. Over the past few years, the roles of epigenetic modifications caused by environmental factors have been intensively studied in relation to the disease pathogenesis, and important advances have been made. This review focuses on the new advances of microRNAs (miRNAs) in the field of SSc research, including the upstream regulatory factors of miRNAs, the downstream targets, and the feedback mechanisms between miRNAs and their targets. We also discussed the correlation of miRNAs and DNA methylation, the miRNAs and the gene polymorphism. Overall, the findings presented in this review illustrated how miRNAs play important roles in the pathogenesis of SSc. However, several unanswered questions continue to impede our understanding of this complex disease. Future research should focus on the identification of new biomarkers for early diagnosis and prognosis, which will help us improve the clinical treatment of patients with SSc. In addition, we discussed the challenges of miRNA study in SSc in the future. Since the miRNA injection may be a promising therapeutic approach for SSc treatment, one of the challenges in the future is to evaluate the therapeutic effects of miRNA and anti-miRNAs using SSc model animals. In light of the fact that one miRNA can target many mRNAs, and one mRNA is targeted by many miRNAs, the effect of miRNA changes on other gene expression should be investigated to evaluate the treatment safety of miRNA injection in vivo.