Jejunal epithelial barrier disruption triggered by reactive oxygen species in early SIV infected rhesus macaques

Intestinal epithelial barrier destruction occurs earlier than mucosal immune dysfunction in the acute stage of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections. At present, however, the cause of compromised gastrointestinal integrity in early SIV infection remains unknown. In the current study, we investigated the effects of SIV infection on epithelial barrier integrity and explored oxidative stress-mediated DNA damage and apoptosis in epithelial cells from early acute SIVmac239-infected Chinese rhesus macaques (Macaca mulatta). Results showed that the sensitive molecular marker of small intestinal barrier dysfunction, i.e., intestinal fatty acid-binding protein (IFABP), was significantly increased in plasma at 14 days post-SIV infection. SIV infection induced a profound decrease in the expression of tight junction proteins, including claudin-1, claudin-3, and zonula occludens (ZO)-1, as well as a significant increase in the active form of caspase-3 level in epithelial cells. RNA sequencing (RNA-seq) analysis suggested that differentially expressed genes between pre- and post-SIV-infected jejuna were enriched in pathways involved in cell redox homeostasis, oxidoreductase activity, and mitochondria. Indeed, a SIV-mediated increase in reactive oxygen species (ROS) in the epithelium and macrophages, as well as an increase in hydrogen peroxide (H₂O₂) and decrease in glutathione (GSH)/glutathione disulfide (GSSG) antioxidant defense, were observed in SIV-infected jejuna. In addition, the accumulation of mitochondrial dysfunction and DNA oxidative damage led to an increase in senescence-associated β-galactosidase (SA-β-gal) and early apoptosis in intestinal epithelial cells. Furthermore, HIV-1 Tat protein-induced epithelial monolayer disruption in HT-29 cells was rescued by antioxidant N-acetylcysteine (NAC). These results indicate that mitochondrial dysfunction and oxidative stress in jejunal epithelial cells are primary contributors to gut epithelial barrier disruption in early SIV-infected rhesus macaques.