ABSTRACT
Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Recent studies have found the aberrant epigenetics in TAO, including DNA methylation, non-coding RNAs, and histone modification. Many genes have an aberrant level of methylation in TAO. For example, higher levels are found in CD14, MBP, ANGLE1, LYAR and lower levels in DRD4 and BOLL. Non-coding RNAs are involved in the immune response (miR-146a, miR-155, miR-96, miR-183), fibrosis regulation (miR-146a, miR-21, miR-29), adipogenesis (miR-27) and are thought to play roles in TAO. MicroRNA is also related to the clinical activity score (miR-Let7d-5p) and may be a predictor of glucocorticoid therapy (miR-224-5p). The quantities of H4 in TAO are increased compared with euthyroid control subjects, and the role of histone modifications in Graves' disease may lead to better understanding of its role in TAO. More studies are needed to explain the role of epigenetics in TAO and provide potential therapeutic strategies.
ABSTRACT
CONTEXT: The activation of orbital fibroblasts, the prime targets in thyroid eye disease (TED), is central to its underlying pathogenesis. OBJECTIVE: We aimed to investigate the mechanism of TED orbital fibroblast activation from the perspective of noncoding RNA regulation. METHODS: Immunofluorescence (IF) staining was applied to evaluate the fibrotic changes in target cells. Cell proliferation was evaluated by 5-ethoxy 2-deoxyuridine and colony-formation assays. Collagen I concentration was determined by enzyme-linked immunosorbent assay. Human microarray analysis was performed on 3 TED and 3 healthy control orbital tissue samples. RESULTS: Bioinformatics analysis showed that cell adhesion signaling factors were differentially expressed in TED tissues, including intercellular adhesion molecule (ICAM)-1, ICAM-4, vascular cell adhesion molecule, and CD44, which were all upregulated in diseased orbital tissues. Long noncoding RNA LPAL2 level was also upregulated in orbital tissues and positively correlated with ICAM-1 and ICAM-4 expression. Stimulation of the TED orbital fibroblasts by transforming growth factor-ß1 (TGF-ß1) significantly increased the expression of ICAM-1, ICAM-4, and LPAL2. Knockdown of LPAL2 in orbital fibroblasts inhibited TGF-ß1-induced increases in cell adhesion factor levels and orbital fibroblast activation. Microarray profiling was performed on TED and normal orbital tissues to identify differentially expressed microRNAs, and miR-1287-5p was remarkably reduced within diseased orbital samples. miR-1287-5p was directly bound to the epidermal growth factor receptor (EGFR) 3' untranslated region and LPAL2, and LPAL2 modulated EGFR/protein kinase B (AKT) signaling through targeting miR-1287-5p. CONCLUSION: The LPAL2/miR-1287-5p axis modulated TGF-ß1-induced increases in cell adhesion factor levels and TED orbital fibroblast activation through EGFR/AKT signaling.
Subject(s)
Cell Adhesion/physiology , Fibroblasts/metabolism , Graves Ophthalmopathy/metabolism , MicroRNAs/metabolism , Orbit/metabolism , RNA, Long Noncoding/metabolism , Adult , Aged , Cell Adhesion Molecules/genetics , Cell Adhesion Molecules/metabolism , ErbB Receptors/genetics , ErbB Receptors/metabolism , Female , Fibroblasts/drug effects , Graves Ophthalmopathy/genetics , Humans , Male , Middle Aged , Orbit/drug effects , RNA, Long Noncoding/genetics , Signal Transduction/physiology , Transforming Growth Factor beta1/pharmacology , Young AdultABSTRACT
The activation and proliferation of human Tenon's fibroblasts (HTFs) play a vital role in the fibrosis in the pathology of the scar formation after the glaucoma filtration surgery. Transforming growth factor ß1 (TGFß1)/Smads signaling has been reported to promote fibrosis. In our previous study, we revealed that TGFß1-induced orbital fibroblast activation and proliferation through Wnt/ß-catenin signaling. As microRNA (miR)-139 could target several factors in Wnt signaling to modulate fibrosis, here, the effect and mechanism of miR-139 in HTF activation and proliferation were investigated. miR-139 overexpression significantly reversed the TGFß1-induced increase in collagen I and α-smooth muscle actin contents and proliferation in HTFs. CTNNB1 and CTNND1 were direct downstream of miR-139 and can significantly restore the suppressive effect of miR-139 on the activation and proliferation in HTFs under TGFß1 stimulation. Smad2/3/4 complex inhibits the transcription activity of miR-139, most possibly by Smad4 binding to the miR-139 promoter. Taken together, we demonstrated a new mechanism of HTF activation and proliferation from the perspective of miRNA regulation, which may provide new strategies for improving the fibrosis after the glaucoma filtration surgery.