Taohong Huazhuo decoction alleviates carbon tetrachloride-induced hepatic fibrosis in rats by inhibiting the nicotinamide adenine dinucleotide phosphate oxidase 4/nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 signaling pathway.

OBJECTIVE: To explore the mechanism underlying the anti-fibrotic effects of Taohong Huazhuo decoction (THHZD, ).

METHODS: Forty percent carbon tetrachloride (CCl4) dissolved in olive oil (2 mL/kg) was intraperitoneally injected twice a week for 8 weeks to induce hepatic fibrosis in rats. The normal group received the same volume of olive oil alone. At week 5, rats injected with CCl4 were intragastrically administered normal saline, 0.1 mg/kg colchicine, 3.285 g/kg THHZD, 6.57 g/kg THHZD, and 13.14 g/kg THHZD once a day for 4 weeks. A biochemical analyzer was used to detect the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (TBIL). Hematoxylin and eosin (HE) staining and Masson staining were performed to evaluate pathological changes in the liver. Enzyme-linked immunosorbent assay (ELISA) was used to determine glutathione (GSH) and malondialdehyde (MDA) levels in the liver, and interleukin-1β (IL-1β), and IL-18 in serum. The levels of α-smooth muscle actin (α-SMA) and reactive oxygen species (ROS) in liver tissues were analyzed by immunohistochemistry and immunofluorescence, respectively. Western blot (WB) was used to analyze the expression levels of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), IL-1β, IL-18, caspase-1, and collagen I in liver. Finally, in vitro experiments were conducted using hepatic stellate cells (HSC-T6).

RESULTS: THHZD improved the pathological changes caused by CCl4 in the liver. Compared with the normal group, the levels of serum ALT, AST, TBIL, IL-1β, and IL-18 in the model group were significantly increased. NOX4, ROS, NLRP3, IL-1β, IL-18, caspase-1, collagen I, α-SMA, and MDA levels were increased in the liver, while GSH levels were decreased. The administration of THHZD to CCl4-exposed rats significantly reversed or eliminated the changes in the above-mentioned indicators. Moreover, THHZD inhibited transforming growth factor-β1 (TGF-β1)-induced high expression of α-SMA and collagen I in HSC-T6 cells, while downregulating the expression of proteins related to the NOX4/NLRP3 signaling pathway in vitro.

CONCLUSION: THHZD reduced the activation of HSCs by inhibiting the NOX4/NLRP3 signaling pathway, thereby exerting anti-hepatic fibrosis effects.