CD34+ orbital fibroblasts contribute to the pathogenesis of thyroid eye disease via miR-182-5p.

Context: CD34+ orbital fibroblasts (OFs) play a pathogenic role in thyroid eye disease (TED). Several micro (mi)RNAs have been shown to promote TED progression.

Objective: This study aims to explore the regulatory effect of miRNAs on CD34+ OFs, to find potential therapeutic target.

Methods: In this case-control study, orbital connective tissues (OCTs) and OFs were obtained from 25 TED patients and 24 healthy donors. MiRNA-seq was performed to examine differential expression of miRNAs in OCTs, and miR-182-5p was selected for subsequent experiments. MiR-182-5p was detected both in CD34+ and CD34- OFs. The upstream regulators of miR-182-5p were studied. Downstream targets of miR-182-5p were analyzed. The functionality of miR-182-5p and its target genes in CD34+ OFs was evaluated.

Results: MiR-182-5p was highly expressed in TED OCTs and their derived CD34+ OFs. TED OCTs displayed increased expression of interluekin (IL)-6, IL-17A, CD34, and phosphorylated STAT3 at Ser727 and Tyr705. Activation of IL-6/STAT3 signaling promoted the expression of miR-182-5p in CD34+ OFs. MiR-182-5p enhanced wound repair ability, proliferation, and RANTES expression while inhibiting apoptosis in CD34+ OFs. CD34+ OFs transfected with miR-182-5p were susceptable to TGF-β-initiated myofibroblast differentiation. Luciferase reporter and pull-down assays revealed Smad7 as the downstream target of miR-182-5p, which modulated the proliferation, migration, fibrosis, and apoptosis of CD34+ OFs.

Conclusion: IL-6/STAT3/miR-182-5p pathway led to activation of CD34+ OFs. MiR-182-5p promoted the proliferation, migration, fibrosis, and anti-apoptosis of CD34+ OFs via targeting Smad7. Our findings suggest that miR-182-5p may potentially serve as a therapeutic target for TED.