Intestinal epithelial formyl peptide receptor 2 contributes to intestinal epithelium homeostasis and injury repair by regulating intestinal stem cell and transit-amplifying cell proliferation and differentiation

Abstract Intestinal stem cells (ISCs) play critical roles in the self-renewal and regeneration of the intestinal epithelium under physiological conditions and after injury, respectively. However, the underlying mechanisms are not fully understood. In this study, we investigate the role of the G protein-coupled receptor formyl peptide receptor 2 (FPR2) in intestinal epithelium homeostasis and regeneration. In mice, knocking out Fpr2 in either intestinal epithelial cells (IECs) or ISCs significantly reduces villus height and crypt depth by impairing ISC and transit-amplifying (TA) cell proliferation and differentiation, primarily TA cell differentiation. Mechanistic studies using intestinal organoid culture and bulk and single-cell RNA sequencing revealed that activation of FPR2 promotes proliferation and differentiation of ISCs and TA cells by activating the wingless/integrated (Wnt), Notch, and Hippo signaling pathways via protein kinase C (PKC)−extracellular signal-regulated kinase (ERK). Under physiological conditions, the Wnt and Notch signaling pathways mediate the regulation of ISC proliferation and differentiation by FPR2. Fpr2 deficiency in mouse IECs exacerbates X-ray- and 5-fluorouracil-induced villus and crypt injury, and delays intestinal epithelium regeneration by reducing ISC and TA cell proliferation. Administering an FPR2 agonist to mice significantly increases survival rates and accelerates intestinal epithelium regeneration after irradiation. Taken together, these results demonstrate that intestinal epithelial FPR2 plays a key role in intestinal epithelium homeostasis and regeneration by promoting ISC and TA cell proliferation and differentiation. FPR2 is a potential therapeutic target against chemotherapy- and radiotherapy-induced intestinal injury.