MiR-155-5p modulates inflammatory phenotype of activated oral lichen-planus-associated-fibroblasts by targeting SOCS1.

Background: Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease. Cytokines are closely associated with OLP development. In addition to immune cells, fibroblasts have been reported to induce regional inflammation. MicroRNA(miR)-155-5p is reportedly increased significantly in OLP and is known to regulate inflammation. This study aimed to investigate the role of miR-155-5p in fibroblasts of OLP lesions.

Methods And Results: Normal mucosal fibroblasts (NFs) and OLP associated-fibroblasts (OLP AFs) were isolated from the oral mucosa of 15 healthy controls and 30 OLP patients. We detected the expression of miR-155-5p and fibroblast activation protein alpha (FAP-α) using quantitative RT-PCR and analyzed their correlation. Interleukin (IL)-6 and IL-8 levels were determined using ELISA. Expression of suppressor of cytokine signaling (SOCS) 1 was analyzed by western blotting. A dual-luciferase reporter assay was performed to investigate the interaction between miR-155-5p and SOCS1. MiR-155-5p and FAP-α were significantly increased and positively correlated in OLP AFs. Overexpression of miR-155-5p in OLP AFs augmented IL-6 and IL-8 release and decreased SOCS1 expression, whereas knockdown of miR-155-5p in OLP AFs decreased IL-6 and IL-8 release. The expression of SOCS1 was downregulated in OLP AFs, and SOCS1 silencing augmented IL-6 and IL-8 production in OLP AFs. Furthermore, miR-155-5p inhibited SOCS1 expression by directly targeting its 3'-UTR in OLP AFs.

Conclusions: MiR-155-5p regulates the secretion of IL-6 and IL-8 by downregulating the expression of SOCS1 in activated OLP AFs. Our results provide novel insights into the pathogenesis of OLP and identify a potential new target for OLP therapy.