J Anim Sci. 2023 Apr 27. pii: skad127. [Epub ahead of print]
The present study aimed to investigate the effect of glutamine (Gln) addition on the damage of porcine intestinal epithelial cells (IPEC-J2) induced by heat stress (HS). IPEC-J2 cultured in logarithmic growth period in vitro were firstly exposed to 42°C for 0.5, 1, 2, 4, 6, 8, 10, 12 and 24 h for cell viability and cultured with 1, 2, 4, 6, 8 or 10 mmol Gln per L of culture media for heat-shock protein 70 (HSP70) expression to determine the optimal disposal strategy (HS, 42℃ for 12 h and HSP70 expression, 6 mmol/L Gln treatment for 24 h). Then IPEC-J2 cells were divided into three groups: control group (Con, cultured at 37 ℃), HS group (HS, cultured at 42 ℃ for 12 h) and glutamine group (Gln + HS, cultured at 42 ℃ for 12 h combined with 6 mmol/L Gln treatment for 24 h). The results showed that HS treatment for 12 h significantly decreased the cell viability of IPEC-J2 (P<0.05) and 6 mmol/L Gln treatment for 12 h increased HSP70 expression (P<0.05). HS treatment increased the permeability of IPEC-J2, evidenced by the increased the fluorescent yellow flux rates (P<0.05) and the decreased transepithelial electrical resistance (P<0.05). Moreover, the down-regulated protein expression of occluding, claudin-1 and ZO-1 were observed in HS group (P<0.05), but Gln addition alleviated the negative effects on permeability and the integrity of intestinal mucosal barrier induced by HS (P<0.05). In addition, HS resulted in the elevations in HSP70 expression, cell apoptosis, cytoplasmic Cytc potential expression and the protein expressions of apoptosis related factors (Apaf1, Caspase-3 and Caspase-9) (P<0.05), however, the reductions in mitochondrial membrane potential expression and Bcl-2 expression were induced by HS (P<0.05). But Gln treatment attenuated HS-induced adverse effects above mentioned (P<0.05). Taken together, Gln treatment exhibited protective effects in protecting IPEC-J2 from cell apoptosis and the damaged integrity of epithelial mucosal barrier induced by HS, which maybe associated with the mitochondrial apoptosis pathway mediated by HSP70.
Keywords: Glutamine; Heat shock protein 70; Heat stress; Intestinal barrier integrity; Mitochondrial apoptosis