The Up-Regulation of miR-146a and miR-29b via Exosomes Protects Against Liver Fibrosis by Inhibiting the TGF-β/Smad3c Signaling Pathway

Background: Hepatic fibrosis is characterized by the increased proliferation and activation of hepatic stellate cells. Transforming growth factor-beta (TGF-β) stimulates these stellate cells, leading to the development of liver fibrosis. MicroRNA-146a and microRNA-29b have been identified as significant regulatory factors in fibrogenesis. Objectives: In this study, we investigated the ability of exosomes to alleviate liver fibrosis by enhancing the antifibrotic effects of miR-146a and miR-29b. Methods: The LX-2 cells were exposed to TGF-β for 24 hours. Subsequently, the cells were treated with exosomes for an additional 24 hours. Following this treatment, the mRNA expression levels of alpha-smooth muscle actin (α-SMA), collagen1α, miR-146a, and miR-29b, as well as the protein levels of phosphorylated Smad3 (p-Smad3), were evaluated. Results: The findings revealed a significant elevation in the expression of α-SMA (5.37-fold, P < 0.0001) and collagen1α (3.87-fold, P < 0.001) genes, as well as an increase in the levels of p-Smad3 protein (5.87-fold, P < 0.0001) in the presence of TGF-β. Moreover, the expression of miR-146a (0.54-fold, P < 0.05) and miR-29b (0.46-fold, P < 0.01) genes exhibited a notable decrease compared to the control group under the influence of TGF-β. In our investigation, the administration of exosomes effectively mitigated the TGF-β-induced up-regulation of α-SMA (3.26-fold, P < 0.01) and collagen1α (1.76-fold, P < 0.01) genes, as well as the p-Smad3 protein (2.86-fold, P < 0.01), in LX-2 cells. Conclusions: Our results suggest that exosomes effectively impede the continuous activation of hepatic stellate cells (HSCs) by enhancing the antifibrotic effects mediated by miR-146a and miR-29b. Moreover, exosomes demonstrate inhibitory effects on the TGF-β/Smad3 signaling pathway, resulting in decreased extracellular matrix (ECM) accumulation in the context of in vitro liver fibrosis.