Protective effects of bovine milk exosomes against oxidative stress in IEC-6 cells.

Abstract

Bovine milk exosomes, which are enriched with microRNAs (miRNAs) and proteins, regulate immune response and growth. In the present study, we aimed to assess the protective effects of bovine milk exosomes against oxidative stress of intestinal crypt epithelial cells (IEC-6). Bovine milk exosomes were isolated and characterized. To assess the protective effects of exosomes, IEC-6 cells were pretreated with exosomes, followed by H2O2. Cell viability and levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPX), reactive oxidative species (ROS), and lactate dehydrogenase (LDH) were measured. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (Ho1) genes, and miR-146a, miR-155, and the HO-1 protein were also determined. The isolated bovine milk exosome were positive for CD63 and CD9 expression. The exosomes were approximately circular and had a diameter of about 67.23nm. Pretreatment of IEC-6 cells with bovine milk exosomes enhanced cell viability; increased SOD and GPX activities; and reduced LDH, ROS, and MDA levels after H2O2 challenge. Further analysis showed that exosome pretreatment increased intracellular miR-146a and miR-155 levels. Exosome pretreatment inhibited the elevation of Nrf2 and Ho1 gene expression induced by H2O2, but promoted HO-1 protein expression. The results indicated that bovine milk exosomes exerted protective effects against oxidative stress in IEC-6 cells.