For instance, SCFAs facilitate the expansion of Th17 cells and ILC3s in the intestine via free fatty acid receptor 2,[13] and Lactobacillus‐derived indole serves as an AHR ligand to enhance IL‐22 transcription in ILC3s.[14] BA metabolism, which involves the intestinal microbiome, also contributes to the functions of peripheral regulatory T cells,[39] ILCs,[40] and intestinal stem cells.[41] In the present study, Lactobacillus contributed to HCA production and enhanced γδT cell and ILC3 development in early life by inhibiting FXR, which effectively prevented intestinal bacterial infections. Here, IL22 is linked to bacterial infectious disease.