Yak milk-derived exosomes alleviate lipopolysaccharide-induced intestinal inflammation by inhibiting PI3K/AKT/C3 pathway activation

Intestinal epithelial cells (IEC) are important parts of the mucosal barrier, whose function can be impaired upon various injury factors such as lipopolysaccha-ride. Although food-derived exosomes are preventable against intestinal barrier injuries, there have been few studies on the effect of yak milk-derived exosomes and the underlying mechanism that remains poorly understood. This study aimed to characterize the ef-fect of exosomal proteins derived from yak and cow milk on the barrier function of IEC-6 treated with li-popolysaccharide and the relevant mechanism involved. Proteomics study revealed 392 differentially expressed proteins, with 58 higher expressed and 334 lower ex-pressed in yak milk-derived exosomes than those in cow exosomes. Additionally, the top 20 proteins with a relatively consistent higher expression in yak milk exosomes than cow milk exosomes were identified. Pro-tein CD46 was found to be a regulator for alleviating inflammatory injury of IEC-6. In vitro assay of the role of yak milk exosomes on survival of IEC-6 in inflam-mation by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay confirmed the effectiveness of yak milk exosomes to increase IEC-6 survival up to 18% for 12 h compared with cow milk exosomes (up to 12%), indicating a therapeutic effect of yak milk exosomes in the prevention of intestinal inflammation. Furthermore, yak and cow milk exosomes were shown to activate the PI3K/AKT/C3 signaling pathway, thus IEC-6 survival. Our demonstrated an important relationship between yak and cow milk exosomes and intestinal inflammation, facilitating fur-ther understanding of the mechanisms of inflammation -driven epithelial homeostasis. Interestingly, compared with cow milk exosomes, yak milk exosomes activated the PI3K/AKT/C3 signaling pathway more to lower the incidence and severity of intestine inflammation, which might represent a potential innovative therapeu-tic option for intestinal inflammation. an important relationship between yak and cow milk exosomes and intestinal inflammation, facilitating further understanding of the mechanisms of inflammationdriven epithelial homeostasis. Interestingly, compared with cow milk exosomes, yak milk exosomes activated the PI3K/AKT/C3 signaling pathway more to lower the incidence and severity of intestine inflammation, which might represent a potential innovative therapeutic option for intestinal inflammation. Key words: yak, milk exosome, intestinal epithelial