Interleukin-17(IL-17)has a central role against bacterial pathogens in the intestine.However,the mechanism by which intestinal IL-17 expression is triggered during bacterial infection is poorly understood.Here,we found enterotoxigenic Escherichia coli(ETEC)increases intestinal IL-17 expression through γ-aminobutyric acid(GABA)signaling,which largely depends on intestinal GABA-producing Lactococcus lactis subsp.lactis.GABA promotes intestinal IL-17 expression in the context of ETEC infection through enhancing mTOR signaling,which activated ribosomal protein S6 kinase 1(S6K1)-early growth response protein 2(EGR2)-growth factor independent 1 transcription repressor(GFI1)pathway.GABAmTOR signaling also affected IL-17 expression in response to Citrobacter rodentium infection and in drug-induced models of intestinal inflammation.Furthermore,a deficiency of slc6a13(GABA transporter 2)in mice promotes Th17 responses against intestinal infection.These findings highlight the importance of GABA-mTOR signaling in intestinal IL-17 expression during intestinal infection,and indicate the potential of GABA signaling in IL-17-associated intestinal diseases.