Objective To investigate the anti-inflammatory and antioxidant effects of berberine for sepsis rats based on kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway.

Methods Adult healthy rats were randomly divided into normal group (20 rats) and sepsis group (80 rats). The sepsis model in rats of the sepsis group was established by cecal ligation and puncture. According to different doses of berberine administered by gavage, the sepsis group was further divided into model group (0 mg/kg, without berberine administration), low-dose group (25 mg/kg), medium-dose group (50 mg/kg) and high-dose group (100 mg/kg), with 20 rats in each group. Both the model group and the normal group were given an equal volume of pure water by gavage. Ten rats were randomly selected from each group for a survival test, and they were continuously observed for 5 days to compare the survival rates among the groups. Lung, kidney, and liver tissues of rats in each group were collected for hematoxylin-eosin (HE) staining, enzyme-linked immunosorbent assay (ELISA), Western blot, and real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) detection. The pathological tissue changes, serum inflammatory cytokine levels, serum biochemical indicator levels, and the relative expression levels of pathway-related proteins and their mRNAs in each group were observed and compared.

Results The survival rates of rats in the medium-dose and high-dose groupsat various time points were all higher than those in the model group, and the differences were statistically significant (P < 0.05). Compared with the normal group, the model group showed increased levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum creatinine (SCr), blood urea nitrogen (BUN), interleukin-6 (IL-6), interleukin-1β (IL-β) and tumor necrosis factor-α (TNF-α). There were obvious pathological injuries in lung, liver, and kidney tissues. The relative expression levels of Nrf2 and heme oxygenase-1 (HO-1) proteins and their mRNAs in lung tissues were decreased, while the relative expression levels of Keap1 mRNA and Keap1 protein were increased, and the differences were statistically significant (P < 0.05). Compared with the model group, the serum SCr and BUN levels in the medium-dose group, and the serum ALT, AST, SCr and BUN levels in the high-dose group were all decreased, with statistically significant differences (P < 0.05). Compared with the model group, the pathological injuries in lung, liver, and kidney tissues of rats in the low-dose, medium-dose, and high-dose groups were all alleviated. The relative expression levels of Nrf2 mRNA and HO-1 mRNA as well as Nrf2 and HO-1 proteins in the lung tissues showed a dose-dependent increase, while the relative expression levels of Keap1 mRNA and Keap1 protein exhibited a dose-dependent decrease. The serum levels of IL-6 and TNF-α in the low-dose group, as well as the serum levels of IL-6, IL-1β and TNF-α in the medium-dose and high-dose groups were all reduced (P < 0.05).

Conclusion Berberine can alleviate the inflammatory response and activate the antioxidant response in sepsis rats by regulating the Keap1/Nrf2/ARE signaling pathway.