The relationship between mirna-26b and connective tissue growth factor in rat models of aortic banding and debanding

Background/Aims: Connective tissue growth factor (CTGF) is a profibrotic factor implicated in pressure overload-mediated myocardial fibrosis. In this study, we determined the role of predicted CTGF-targeting microRNAs (miRNAs) in rat models of aortic stenosis and reverse cardiac remodeling. Methods: Minimally invasive ascending aortic banding was performed in 24 7-week-old male Sprague-Dawley rats, which were divided into three groups. The banding group consisted of eight rats that were sacrificed immediately after 6 weeks of aortic constriction. The debanding group underwent aortic constriction for 4 weeks and was sacrificed 2 weeks after band removal. The third group underwent sham surgery. We investigated the expression of CTGF, transforming growth factor-β1 (TGFβ1), and matrix metalloproteinase-2 using ELISA and ex-amined miRNA-26b, miRNA-133a, and miRNA-19b as predicted CTGF-target-ing miRNAs based on miRNA databases in 24-hour TGFβ-stimulated and TG-Fβ-washed fibroblasts and myocardial tissues from all subjects. Results: CTGF was elevated in 24-hour TGFβ-stimulated fibroblasts and de-creased in 24-hour TGFβ-washed fibroblasts. miRNA-26b was significantly increased in TGFβ-washed fibroblasts compared with control and TGFβ-stimulated fibroblasts (p < 0.05). CTGF expression was significantly higher in the banding group than that in the sham and debanding groups. The relative expression levels of miRNA-26b were higher in the debanding group than in the banding group. Conclusions: The results of our study using models of aortic banding and de-banding suggested that miRNA-26b was significantly increased after aortic de-banding. The in vitro model yielded the same results: miRNA-26b was upregulat-ed after removal of TGFβ from fibroblasts.