The role of microRNA-5196 in the pathogenesis of systemic sclerosis.

Systemic sclerosis (SSc) is a chronic autoimmune disease characterised by tissue fibrosis and immune abnormalities. Recent evidence suggests that activated circulating monocytes from patients with SSc play an important role in early stages of SSc pathogenesis due to enhanced expression of tissue inhibitor of metalloproteinases 1 (TIMP-1), IL-8 and reactive oxygen species (ROS) induction. However, the exact factors that contribute to chronic inflammation and subsequently fibrosis progression are still unknown. The expression pattern of IL-8, TIMP-1, AP-1 transcription factor-Fra2 and ROS induction in peripheral blood monocytes following DZNep (histone methyltransferase inhibitor) and TLR8 agonist stimulation was investigated. Exogenous microRNA-5196, which is predicted to bind 3'UTR of Fra2 gene, was delivered to reverse profibrotic phenotype in monocytes. Expression of circulating microRNA-5196 was correlated with SSc parameters. DZNep + TLR8 agonist stimulation enhanced profibrotic TIMP-1, IL-8 and ROS generation in HC and SSc monocytes. As opposed by the decrease of miRNA-5196 and antioxidant SOD1 expression in SSc monocytes. Exogenous delivery of microRNA-5196 reduced Fra2 and TIMP-1 expression suggesting that it may be used as a potential modulator of fibrogenesis in SSc. Circulating microRNA-5196 was significantly increased in SSc and positively correlated with CRP level but not with Rodnan skin score or ESR. These results suggest that microRNA-5196 can be used as a potential biomarker characterising SSc. Overall, this study may open new possibilities for the development of microRNA-5196-based diagnostics and therapy in early phases of SSc.