NR1H4 and dermatitis: Gut microbiota-derived SCFAs, which inhibit IL-17 production by intestinal γδ T cells (38), and in vitro supplementation with Bifidobacterium short CCFM683 improved PSO-like dermatitis by restoring the intestinal microbiome of PSO model rats, promoting BAs production, modulating the FXR/NF-κB pathway, reduces the generation of inflammatory cytokines, modulating keratinocytes and maintaining epidermal barrier function to attenuate PSO (100).