Protective effects of ZIP8 on Toxoplasma gondii-induced acute hepatocyte injury in mice

Toxoplasma gondii (T. gondii), as an intracellular protozoan parasite, has the potential to disturb the homeostasis of trace metal elements in host cells. Zinc (Zn) is one of those essential metals that is required for combating infection. Zinc cellular homeostasis is controlled by zinc membrane transporters, including efflux and influx transporters. One of the Zrt-Irt-like protein (ZIP) transporters, ZIP8, facilitates zinc influx into the cytosol. It was recently reported to play significant roles in facilitating Zn uptakes during infection. Here, we investigated the function of ZIP8 in host defense against T. gondii infection in cultured alpha mouse liver 12 (AML12) hepatocytes and mice, with loss of ZIP8 function. Herein, C57BL/6 J female wild-type (WT) and ZIP8-KD mice (Slc39a8 knockdown mice), that were infected with tachyzoites of ToxoDB#9(TgCtwh3), were used as a model of acute toxoplasmosis. AML12 hepatocytes were transfected with lentivirus (LV), with silenced ZIP8 expression. Finally, we observed the function of hepatocytes pretreated with ZnCl₂ before TgCtwh3 infection in vivo and in vitro. In vivo, the levels of zinc ions and ZIP8 protein were upregulated after TgCtwh3 infection. ZIP8 knockdown exacerbated liver damage, further decreased antioxidant enzyme activity, promoted inflammatory mediator expression, and upregulated the rate of apoptosis. ZnCl₂ pretreatment before TgCtwh3 infection improved liver injury, increased antioxidant enzyme activity, restrained the expression of inflammatory mediators, and decreased the rate of apoptosis. The results in vitro were almost the same as those in vivo. This study defines the function of ZIP8-dependent zinc in hepatocyte damage during intracellular pathogen infection. Reagents that regulate ZIP8 activity might be developed as therapeutics to protect the liver function of toxoplasmosis.