Microbiomics and metabolomics insights into the mechanism of egg yolk phosphatidylcholine enhancing intestinal immunity

Egg yolk phosphatidylcholine (EYPC), the most vital functional lipid in egg yolk, has demonstrated neuroprotective, antibacterial, and cardioprotective effects. However, there is little information about its immunoregulation effect. Therefore, the aim of this study is to assess the effects and mechanisms of EYPC on intestinal immune homeostasis through an immunosuppressed mouse model induced by cyclophosphamide (CTX). The protective effect of intestinal immunity was evaluated on the basis of immune organ indices, intestinal tight junction (TJ) proteins, sIgA and cytokine secretion, nuclear transcription factor levels, and the equilibrium between Th1 and Th2 cells. It was shown that EYPC obviously inhibited thymus and spleen atrophy, enhanced the expression of TJ proteins, promoted the secretion of sIgA and cytokines, increased the levels of Th1 and Th2 cells, and also modulated the balance of Th1 and Th2 cells. The composition of the gut microbiota and metabolites were discussed to outline mechanisms. The results elucidated that EYPC could alleviate the gut microbiota dysbiosis caused by CTX <i>via</i> reducing the relative abundance of <i>Akkermansia muciniphila</i> and promoting the proliferation of <i>Prevotella</i> and <i>Lactobacillus reuteri</i>. Furthermore, EYPC improved the fecal metabolic profile, restoring the relative content of 13 metabolites and regulating bile secretion. Collectively, these findings suggested that EYPC may contribute to intestinal immune homeostasis through modulating gut microbiota and their metabolism, highlighting its potential as an immunomodulator.