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

Abstract

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.

Role of microRNA-146a in regulation of fibrosis in orbital fibroblasts from patients with Graves’ orbitopathy

“…However, the role played by miR-146a in GO may be a little more complex. In contrast to the results of our previous study, Wang et al 30 reported that miR-146a exerted a pro-inflammatory effect (thus increasing IL-6 production), inhibiting the miR-146a target gene notch2, leading to exacerbation of GO, which is consistent with the findings of our previous study 30. Wei et al 31 reported that the circulating miR-146a level was significantly decreased in GO compared with non-GO subjects.…”

Integrated Transcriptome and Proteome Analyses Reveal the Regulatory Role of miR-146a in Human Limbal Epithelium via Notch Signaling

“…Overexpression of miR-146a induced repression of Numb and an increase in Notch-1 expression level, which is in agreement with earlier verified miR-146a direct target studies [ 63 , 64 , 65 ]. This treatment decreased Notch-2 expression level, which is also in agreement with previous data [ 41 , 42 ].…”

“…miR-146a is an important regulator of many cellular functions and targets different genes in different cell types [ 40 , 41 , 42 ]. It plays a major role in several diseases, such as diabetes [ 40 ], cancer [ 41 ], and Graves ophthalmopathy [ 42 ], and its association with different pathways suggests its involvement in cell migration [ 9 , 10 , 43 ], invasion [ 44 ], differentiation [ 45 ], and proliferation [ 44 ]. Our previous studies also revealed that miR-146a plays a regulatory role in corneal wound healing and limbal epithelial stem cell maintenance in normal and diabetic corneas [ 9 , 10 ].…”

MicroRNA-146a downregulates the production of hyaluronic acid and collagen I in Graves' ophthalmopathy orbital fibroblasts

“…Previous studies have indicated that miR-146a participated in several types of autoimmune diseases, including rheumatoid arthritis (17). In a previous report, miR-146a has been revealed to reduce the pathogenesis of GO via exerting anti-inflammatory and anti-fibrotic effects (11), while another study demonstrated that the upregulation of miR-146a promoted inflammation and disease progression (20). These studies have indicated that the effect of miR-146a on GO may be complex, as miR-146a may exert distinct functions in different cell types or interact with various target mRNAs.…”

“…miR-146a has been reported to serve a role in a variety of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus and osteoarthritis (19). Previous studies have indicated that miR-146a regulated the expression of inflammatory factors in GO orbital fibroblasts (19,20). The current study aimed to investigate the effect of miR-146a on the production of HA and collagen I in GO orbital fibroblasts, and indicated that miR-146a may be used as a novel target for the treatment of GO.…”