The Effects of Zinc Oxide Nanoparticles on Antioxidation, Inflammation, Tight Junction Integrity, and Apoptosis in Heat-Stressed Bovine Intestinal Epithelial Cells In Vitro

Zinc oxide nanoparticles (nano-ZnO) have diverse applications in numerous biomedical processes. The present study explored the effects of these nanoparticles on antioxidation, inflammation, tight junction integrity, and apoptosis in heat-stressed bovine intestinal epithelial cells (BIECs). Primary BIECs that were isolated and cultured from calves either were subjected to heat stress alone (42°C for 6 h) or were simultaneously heat-stressed and treated with nano-ZnO (0.8 μg/mL). Cell viability, apoptosis, and expression of genes involved in antioxidation ( Nrf2 , HO-1 , SOD1 , and GCLM ), inflammation-related genes ( TLR4 , NF-κB , TNF-α , IL-6 , IL-8 , and IL-10 ), intestinal barrier genes ( Claudin , Occludin , and ZO-1 ), and apoptosis-related genes ( Cyt-c , Caspase-3 , and Caspase-9 ) were assessed to evaluate the effect of nano-ZnO on heat-stressed BIECs. The nanoparticles significantly increased cell viability and decreased the rate of apoptosis of BIECs induced by heat stress. In addition, nano-ZnO promoted the expression of antioxidant-related genes HO-1 and GCLM and anti-inflammatory cytokine gene IL-10 , and inhibited the pro-inflammatory cytokine-related genes IL-6 and IL-8 . The nanoparticles also enhanced expression of the Claudin and ZO-1 genes, and decreased expression of the apoptosis-related genes Cyt-c and Caspase-3 . These results reveal that nano-ZnO improve the antioxidant and immune capacity of BIECs and mitigate apoptosis of intestinal epithelial cells induced by heat stress. Thus, nano-ZnO have potential for detrimental the adverse effects of heat stress in dairy cows.