In conclusion, our results suggest that the lack of Nfil3 in HFD-fed mice is associated with GM (abundance increase: M. intestinale and D. newyorkensis and abundance decrease: K. alysoides and A. muris), resulting in alterations in BA pool composition, affecting BA synthesis regulation via Nfil3-FXR-Fgf15/fgfr4 signaling, reducing Ly6C+ macrophage recruitmƒent, and preventing liver steatosis and inflammation (Fig. 7). The gene discussed is FGFR4; the disease is fatty liver disease.