PD-1 blockade promotes mucosal CD4+ T cell IL-10 production through altering microbiota to reduce intestinal ischemia reperfusion injury.

PD-1 blockade therapy is widely used in clinical practice. Intestinal ischemia reperfusion (IR) injury is a serious clinical complication that leads to remote organ damage through disruption of the gut barrier. However, the effects of PD-1 blockade on gut homeostasis and intestinal IR injury remain unclear. Here, we demonstrate that, in contrast to PD-1 deficiency, PD-1 blockade activates intestinal immunoglobulin A (IgA) responses in mice via a MyD88-dependent pathway. The increased production and bacteria-binding capacity of IgA induced by PD-1 blockade significantly reshape the gut microbial composition and metabolite profile. Furthermore, PD-1 blockade promotes intestinal mucosal CD4+ T cell IL-10 production. Notably, microbiota depletion by antibiotics attenuates intestinal IL-10 production, whereas transplantation of PD-1 blockade-altered microbiota facilitates IL-10 upregulation. These IL-10 enhancements appears to be driven by an increase in , a recognized butyrate-producing bacterium, and elevated levels of microbiota-derived butyrate, which were increased after PD-1 blockade and significantly correlated with enhanced IL-10 production in the intestinal mucosa. The upregulation of intestinal IL-10 following PD-1 blockade suppresses inflammatory activation, thereby ameliorating the gut barrier impairment and remote organ injury induced by intestinal IR. In addition, we show that, and butyrate supplementation enhances IL-10 expression in CD4+ T cells through PI3Kγ/phospho-mTOR signaling. Collectively, these findings indicate that PD-1 blockade promotes intestinal mucosal CD4+ T cell IL-10 production by modulating immune‒microbiota interactions and subsequently mitigates intestinal IR-induced gut barrier dysfunction and organ damage.