Abstract:

Objective To investigate the protective effect of adult-worm excretory-secretory protein (AES) of Trichinella spiralis on sepsis-induced acute liver injury. Methods Twenty-four male BALB/c mice were randomly divided into sham operation group (Sham group), cecal ligation and puncture group (CLP group), AES treatment group (AES + CLP group), and AES control group (AES + Sham group) (n = 6 in each group). The mice in the CLP group and AES + CLP group received cecal ligation and puncture procedure to induce sepsis-associated acute liver injury. At 30 min after surgery, intraperitoneal injection of PBS or AES (25 μg) was performed. At 12 h after surgery, the serum levels of alanine transaminase (ALT) and aspartate transaminase (AST) were determined and mice were sacrificed to prepare paraffin sections of the liver for HE staining. Protein levels of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) in liver were measured by Western blotting. Expression of nuclear factor-κB (NF-κB) p65 in hepatocytes was detected by immunohistochemistry, and the nuclear positive rate was analyzed. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β in liver were determined with ELISA. Results At 12 h after surgery, the serum levels of ALT and AST in the CLP group [(269.83 ± 77.60) and (712.00 ± 186.52) IU/L, respectively] were both significantly higher than those in the Sham group [(45.00 ± 15.01), (132.50 ± 36.95) IU/L] and the AES + CLP group [(136.67 ± 30.27), (419.00 ± 60.86) IU/L] (P < 0.05), and the serum levels of ALT and AST in the AES + Sham group [(50.83 ± 13.24), (134.67 ± 35.78) IU/L] had no significantly difference with those in the Sham group. HE staining revealed disordered hepatic cords, hepatocyte swelling, and infiltrations of inflammatory cells in the CLP group, but significantly ameliorated injury in the AES + CLP group. Results of Western blotting showed that the relative protein levels of TLR4 and MyD88 in the CLP group (0.66 ± 0.12, 0.69 ± 0.13, respectively) were significantly higher than those in the Sham group (0.31 ± 0.06, 0.22 ± 0.04) (P < 0.05). There was a significant difference between the AES + CLP and CLP groups in MyD88 level (0.47 ± 0.06 vs. 0.69 ± 0.13), but not for TLR4 (0.56 ± 0.09 vs. 0.66 ± 0.12). Immunohistochemistry revealed that the nuclear positive rate of NF-κB p65 was significantly higher in the CLP group [(18.93 ± 2.91)%] than in the Sham group [(0.5 ± 0.21)%] and the AES + CLP group [(9.6 ± 1.59)%] (P < 0.05). ELISA revealed that the levels of TNF-α, IL-6 and IL-1β in the CLP group [(26.21 ± 2.96), (80.80 ± 9.94) and (28.99 ± 3.70) pg/mg, respectively] were all significantly higher than those in the Sham group [(15.42 ± 1.21), (47.70 ± 4.77) and (16.86 ± 1.68) pg/mg] and the AES + CLP group [(18.93 ± 2.04), (61.82 ± 7.24) and (23.18 ± 2.21) pg/mg] (P < 0.05). Conclusion AES reduces the levels of TNF-α, IL-6 and IL-1β via decreasing MyD88 expression and the nuclear positive rate of NF-κB in liver, thereby relieving sepsis-induced acute liver injury in mice.

Key words: Trichinella spiralis, Sepsis, Acute liver injury, Excretory-secretory protein, Toll-like receptor 4, Myeloid differentiation factor 88, Nuclear factor-κB;