Objective To establish a rat model of liver fibrosis and investigate the effect and possible mechanism of pirfenidone(PFD)on the intestinal mucosal barrier in rats with liver fibrosis.Methods Thirty rats were equally divided into normal control,carbon tetrachloride(CCL4),and CCL4+PFD groups.The liver fibrosis model was established by intraperitoneal injection of 50％CCL4 olive oil solution at 0.1 mL/100 g in the lower abdomen,while the normal control group received an equal volume of normal saline.After successful modeling,the CCL4+PFD group received 200 mg/kg PFD solution by gavage,while the other groups received an equal volume of normal saline for 4 consecutive weeks.All rats were then anesthetized and sacrificed.Liver and spleen indexes were calculated,and blood was collected from the portal vein to detect serum levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST),tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),and lipopolysaccharide(LPS).Masson staining of the liver and HE staining of the ileum were performed to observe histomorphological changes.Immunohistochemical staining(IHC)and Western blot were used to detect the expression levels of claudin-1 and occludin in the ileum.Results The rat model of liver fibrosis was successfully established.The liver lobule structure was clear in the normal control group,with no fibrous deposition in the portal area.In the CCL4 group,the liver lobule structure was disordered,with significant fibrous hyperplasia around the central vein and portal area and formation of numerous fibrous septa.The CCL4+PFD group showed less fibrous hyperplasia around the central vein and portal area,with thinner and fewer fibrous septa compared to the CCL4 group.The liver and spleen indexes were significantly higher in the CCL4 group than in the normal control group(P＜0.01)and decreased after PFD treatment(P＜0.05).Serum levels of AST,ALT,IL-6,TNF-α,and LPS were higher in the CCL4 group than in the normal control group and decreased after PFD treatment(P＜0.05).Compared to the normal control group,the CCL4 group showed disordered ileal mucosal epithelial structure,shorter and wider villi,and rupture,shedding,and inflammatory cell infiltration in some mucosal epithelium.PFD treatment improved the structure of ileal villi,with increased height and width compared to the CCL4 group.The expression of tight junction proteins occludin and claudin-1 in the ileum was reduced in the CCL4 group compared to the normal control group(P＜0.05)and increased after PFD treatment(P＜0.05).Conclusion In addition to its anti-liver fibrosis effect,PFD can alleviate small intestinal mucosal damage and protect the intestinal mucosal barrier in rats.The mechanism may involve upregulation of the expression of tight junction(TJ)proteins claudin-1 and occludin in the ileum and reduction of serum LPS and inflammatory factors.
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