Recombinant Trichinella spiralis-53000 protein alleviates liver damage due to lipopolysaccharides via M2 macrophage activation

Abstract

To evaluate if recombinant Trichinella spiralis-53 000 protein (rTsP53) could alleviate liver damage caused by lipopolysaccharides (LPS) via M2 macrophage activation. Sixty male BALB/c mice were randomly divided into LPS group, LPS + phosphate buffer saline (PBS) group and rTsP53 intervention group by random number table, with 20 mice in each group. Intraperitoneal injection of 15 μg/kg LPS was performed for all the mice in the three groups after 8 hours of fasting. The mice in LPS + PBS group were injected with PBS after 1 hour of LPS injection. The mice in the rTsP53 intervention group were injected with rTsP53 (5 mg/kg) after 1 hour of LPS injection. After 48 hours all the mice were sacrificed. Peritoneal macrophages were harvested and flow cytometry (FCM) was used to detect markers CCR7 (M1) and CD206 (M2) of macrophages. Hepatic tissue was harvested for pathological study after hematoxylin-eosin (HE) staining, and double staining immunofluorescence was used to detect F4/80⁺ HLA-DR⁺ and F4/80⁺ CD163⁺. Peripheral blood serum was harvested to detect the levels of aspartate transaminase (AST) and alanine transaminase (ALT). Compared with LPS and LPS + PBS groups, survival rate of mice of rTsP53 intervention group was significantly elevated (90% vs. 25%, 30%, both P<0.01), and the pathological injury of the liver was significantly ameliorated, and the hepatic structure was better preserved. The transaminase in rTsP53 intervention group was significantly lower than that of LPS and LPS + PBS groups (ALT: 97.7 ± 8.5 U/L vs. 181.7 ± 19.5 U/L, 173.7 ± 17.2 U/L; AST: 142.7 ± 12.1 U/L vs. 235.7 ± 9.9 U/L, 213.7 ± 6.7 U/L, all P<0.05), FITC-CD206⁺ proportion of peritoneal macrophage was significantly higher [(17.75 ± 0.30)% vs. (1.38 ± 0.13)%, (1.36 ± 0.05)%, both P<0.05] while PE-CCR7(+) proportion [(6.89 ± 0.11)% vs. (15.30 ± 0.64)%, (14.96 ± 0.93)%, both P<0.05] was significantly lower. Fluorescence intensity of macrophages with F4/80⁺ CD163⁺ double staining for liver sections was significantly increased (0.36 ± 0.01 vs. 0.29 ± 0.02, 0.31 ± 0.01, both P<0.05), while there was no significant difference in the fluorescence intensity of macrophages with F4/80⁺ HLA-DR⁺ double staining (0.30 ± 0.01 vs. 0.30 ± 0.02, 0.31 ±0.01, both P>0.05). There was no significant difference of above results between LPS group and LPS + PBS group (all P>0.05). rTsP53 could ameliorate liver damage caused by LPS and improve animal's survival via the activation of M2 macrophage.