Vitamin D receptor mediates liver ischemia and reperfusion injury by autophagy-regulated M2 macrophage polarization

Liver ischemia and reperfusion (IR) injury is the major complication of liver-related operations. Macrophage polarization has an essential effect on the mechanism of liver IR injury. Vitamin D receptor (VDR) has been found to regulate macrophage polarization and alleviate IR injury. Nevertheless, the correlation between VDR and macrophage polarization in liver IR injury has not been clearly elucidated. VDR knockout mice and wild-type littermates underwent partial liver ischemia for 90 min and reperfusion for 6 h. RAW264.7 cells were also used to verify the influence of VDR on macrophage polarization in vitro. VDR activation could promote M2 macrophage polarization and then reduce liver injury. In contrast, VDR deficiency aggravated the liver injury by disturbing M2 macrophage polarization. Moreover, autophagy participated in the effect of VDR on M2 macrophage polarization through mediating suppressor of cytokine signaling. Therefore, VDR plays a vital influence in liver IR injury. The protective role of VDR activation in liver IR injury is related to regulate M2 macrophage polarization by autophagy.