Aloin Attenuates Oxidative Stress, Inflammation, and CCl4-Induced Liver Fibrosis in Mice: Possible Role of TGF-β/Smad Signaling

Liver fibrosis refers to the excessive buildup of extracellular matrix (ECM) components in liver tissue. It is considered a pathological response to liver damage for which there is no effective treatment. Aloin, an anthraquinone compound isolated from the aloe plant, has shown good pharmacological effects in the treatment of gastric cancer, ulcerative colitis, myocardial hypertrophy, traumatic brain injury, and other diseases; however, its specific impact on liver fibrosis remains unclear. To address this gap, we conducted a study to explore the mechanisms underlying the potential antifibrotic effect of aloin. We constructed a mouse liver fibrosis model using carbon tetrachloride (CCl4) dissolved in olive oil as a modeling drug. Additionally, a cellular model was developed by using transforming growth factor β1 (TGF-β1) as a stimulus applied to hepatic stellate cells. After aloin intervention, serum alanine aminotransferase, hepatic hydroxyproline, and serum aspartate aminotransferase were reduced in mice after aloin intervention compared to CCl4-mediated liver injury without aloin intervention. Aloin relieved the oxidative stress caused by CCl4 via reducing hepatic malondialdehyde in liver tissue and increasing the level of superoxide dismutase. Aloin treatment decreased interleukin (IL)-1β, IL-6, and tumor necrosis factor-α and increased the expression of IL-10, which inhibited the inflammatory response in liver injury. In addition, aloin inhibited the activation of hepatic stellate cells and reduced the level of α-smooth muscle actin (α-SMA) and collagen type I. In cell and animal experiments, aloin attenuated liver fibrosis, acting through the TGF-β/Smad2/3 signaling pathway, and mitigated CCl4- and TGF-β1-induced inflammation. Thus, the findings of this study provided theoretical data support and a new possible treatment strategy for liver fibrosis.