SEA Alleviates Hepatic Ischaemia-Reperfusion Injury by Promoting M2 Macrophage Polarisation

Hepatic ischaemia-reperfusion (I/R) injury is a frequent and nearly inevitable pathophysiological process without widely accepted effective therapy. Soluble egg antigen (SEA) of Schistosoma japonicum (S. japonicum) is the main mediators capable of regulating immunological activities and has received increased attention in immune-mediated diseases. But its role in hepatic I/R injury has not been well defined. This study aimed to elucidate whether SEA protects liver against hepatic I/R injury and explore underlying mechanism. After intraperitoneal injecting SEA three times a week for 4 weeks, mice underwent 70% hepatic I/R injury. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), haematoxylin-eosin (HE) and TdT-mediated dUTP nick-end labelling (TUNEL) staining were used to evaluate liver injury. The severity related to the inflammatory response was also investigated. Furthermore, immunofluorescence was used to detect macrophage polarisation. Compared with the hepatic I/R injury group, SEA pretreatment significantly alleviated hepatic I/R injury induced liver damage, apoptosis and inflammatory. Interestingly, SEA enhanced the polarisation of macrophages towards M2 macrophages in vivo. We are the first to investigate the therapeutic efficacy of S. japonicum SEA in a hepatic I/R injury model in mice. We provided the first direct evidence that SEA attenuated hepatic I/R injury by promoting M2 macrophage polarisation.