Selenium deficiency induces ileitis in broilers via selenoprotein S reduction-mediated mtROS-driven pyroptosis-NET bidirectional regulation

Selenium (Se) deficiency is a widespread nutritional disorder in poultry, frequently associated with severe intestinal inflammation and substantial economic losses. However, the precise molecular events linking Se deficiency to ileitis remain poorly defined. Here, we identify a previously unrecognized pathogenic cascade centered on Selenoprotein S (SelS) downregulation, which triggers a destructive crosstalk between enterocyte pyroptosis and neutrophil extracellular trap (NET) formation in broiler ileitis. Using Se-deficient broilers and a co-culture system of chicken primary intestinal epithelial cells (CIECs) with neutrophils, we demonstrate that SelS silencing is a critical initiating event. Mechanistically, SelS loss directly activated Caspase-1/GSDMD-mediated pyroptosis in CIECs while simultaneously promoting massive NET release. Notably, pyroptotic CIECs stimulated NET formation, and in turn, accumulated NETs further exacerbated CIEC pyroptosis, forming a self-amplifying positive feedback loop that magnifies mucosal injury. Mitochondrial reactive oxygen species (mtROS) emerged as the indispensable upstream driver, as mtROS overproduction was both necessary and sufficient to trigger this loop. Pharmacological blockade of mtROS with Mito-TEMPO, inhibition of pyroptosis with VX765, or degradation of NETs with DNase I each effectively disrupted this circuit and alleviated intestinal barrier disruption, as evidenced by restored tight junction proteins and goblet cell populations. Collectively, our findings unveil a novel mtROS-driven pyroptosis-NET crosstalk loop as the core mechanism of Se deficiency-induced ileitis, with SelS serving as the molecular linchpin. This work not only provides mechanistic insights into nutritional immunology but also establishes the SelS/mtROS axis as a promising therapeutic target for precision nutritional strategies to combat intestinal inflammatory disorders in poultry production.