REDD1 attenuates cholestatic liver fibrosis and suppresses PI3K/AKT/mTOR pathway.

Introduction: Liver fibrosis is reversible. Cholestasis is an important factor causing liver fibrosis. However, there are currently no effective anti-fibrotic drugs for cholestatic liver fibrosis in clinical practice. Methods: mRNA sequencing was performed using mouse bile duct ligation (BDL) of liver tissue, and RT-qPCR was used to screen for the target gene REDD1. Immunohistochemistry was used to detect the expression of REDD1, CD68, α-SMA, and PI3K/AKT/mTOR signaling pathways in primary biliary cholangitis (PBC) patient liver tissue. Subsequently, adenovirus mediated REDD1 was transfected into mouse liver tissue via tail vein to evaluate its therapeutic effect. Results: RNA sequencing revealed REDD1 was significantly upregulated in BDL-induced fibrotic liver tissue. REDD1 expression correlated positively with α-SMA and CD68 in PBC patients, suggesting its involvement in fibrogenesis. However, REDD1 overexpression ameliorated BDL-induced liver injury, reduced serum ALT/AST levels, and decreased collagen deposition, as evidenced by histological and molecular analyses (α-SMA and collagen I), indicating that REDD1 exhibited compensatory elevation in liver fibrosis. Additionally, PI3K/AKT/mTOR pathway was involved in the improvement of liver fibrosis by REDD1. Conclusions: These findings highlight REDD1 as a potential therapeutic target for liver fibrosis, acting probably through modulation of the PI3K/AKT/mTOR pathway to mitigate fibrotic processes.