Specific bile acids can elicit the type-I interferon response through the cGAS-STING pathway.

Bile acids are metabolites crucial to lipid metabolism and immune regulation, yet their biological functions and mechanistic underpinnings remain largely elusive. In this study, we demonstrate that specific bile acids DCA, CDCA and LCA can trigger the type-I interferon response (IFN-I) in various cells through the cytosolic DNA-sensing cGAS-STING pathway. Phosphoproteomics indicates that bile acids can elicit a wide array of changes across numerous signaling pathways, culminating in the downregulation of Bcl-2 and p-BAD, resulting in the formation of Bax/Bak pore for the cytosolic release of mitochondrial DNA. The induction of the IFN-I response also depends on inter-organelle interactions among the endolysosome, ER, and mitochondria, leading to calcium flux and mitochondrial dysfunction, which also contribute to mtDNA release. Further, while systemic administration of bile acid DCA can trigger the STING-dependent IFN-I response in various tissues and bloodstream, tissue-restricted application of DCA can exert antiviral and antitumor effects. Together, these findings identify the cGAS-STING pathway as a mechanistic underpinning of specific bile acids and provide new insights into harnessing bile acids for future therapy.