Mechanism of MicroRNA-146a/Notch2 Signaling Regulating IL-6 in Graves Ophthalmopathy

Background/aims: We intended to investigate the significance of microRNA-146a, Notch2 and IL-6 on Graves ophthalmopathy (GO) and the relationships among them.

Methods: About 27 GO patients were incorporated in this study, including 13 patients with inactive GO and14 patients with active GO. Another 15 patients who had previously received strabismus orthopedics or ophthalmectomy due to trauma were selected as the control population. QRT-PCR assay was used to detect microRNA-146a and Notch2 expression levels in plasma. MTT assay and flow cytometry were respectively used to assess the viability and mitosis of the fibroblasts isolated from orbital connective tissue. Double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was employed to detect serum IL-6 levels. The dual luciferase reporter gene assay was used to verify the targeting relationship between microRNA-146a and Notch2.

Results: Compared with the control group, the relative expression of miR-146a was significantly increased whereas the relative expression of Notch2 was significantly decreased (all P < 0.05) in GO patients compare with the control. Notch2 can be directly targeted by microRNA-146a. The over-expression of miR-146a markedly facilitated Orbital Fibroblasts (OFs) viability and mitosis whereas markedly suppressed cell apoptosis (all P < 0.05). Exogenous microRNA-146a mimics could down-regulat the expression of Notch2 and up-regulate IL-6 (P < 0.05). The inhibition of microRNA-146 resulted in the elevated expression of Notch2 and decreased expression of IL-6 (P < 0.05).

Conclusion: MicroRNA-146a may increase the IL-6 levels and exacerbate GO by directly targeting Notch2.