Effects of Schistosoma japonicum infection on the expression of Arg-1 and Fizz-1 proteins in liver tis-sues of mice with high-fat diet induced obesity

Objective To investigate the effects of Schistosoma japonicum infection on selective activation of macrophages and insulin resistance in liver tissues of mice with high-fat diet induced obesity and the possible mechanism. Methods Thirty-six male C57BL/ 6J mice were randomly divided into 3 groups in-cluding normal control group（NC group,n=12）,high-fat diet feeding group（HF group,n=12）and high-fat diet feeding with Schistosoma japonicum infection group（HSj group,n=12）. Specimens were collected 6 and 12 weeks after high-fat diet feeding. The levels of fasting blood glucose（FBG）,fasting plasma insulin （FINS）and homeostasis model assessment for insulin resistance index（HOMA-IR）were detected. The ex-pression of interleukin-6（IL-6）,arginase-1（Arg-1）and found in inflammatory zone-1（Fizz-1）at mRNA and protein levels were detected by semi-quantitative reverse transcription polymerase chain reaction（RT-PCR）and immunohistochemistry,respectively. Results The mice from HF group showed higher levels of HOMA-IR than those form NC group and HSj group by the end of 6 and 12 weeks after infection（P﹤0. 05）. The levels of HOMA-IR in mice from HF group were increased by the end of week 12 after infection as com-pared with those at week 6（P〉0. 05）. The levels of IL-6 in mice from both HF group and HSj group were higher than those from NC group by the end of week 6 after infection（P﹤0. 05）. Higher levels of IL-6 were detected in mice from HF group as compared with those from HSj group and NC group by the end of week 12 after infection（P﹤0. 05）. The expression of Arg-1 and Fizz-1 in mice form HF group were lower than those from NC group by the end of 6 and 12 weeks after infection（P﹤0. 05）. Arg-1 was highly expressed in mice form HSj group,followed by those from NC and HF groups 12 weeks after infection. The expression of Fizz-1 in mice from HSj group was the highest among the three groups by the end of week 6 and 12 after infection （P﹤0. 05）. Conclusion The proinflammatory effects on mice with diet induced obesity were induced during acute infection of Schistosoma japonicum cercariae（6 weeks）. The chronic infection of Schistosoma japonicum cercariae（12 weeks）might be helpful in reversing hepatic insulin resistance in mice with diet induced obesity by changing the polarity of macrophages in liver tissues. Key words: Schistosoma japonicum; Arg-1;  Fizz-1; Insulin resistance