Targeted Lipid Metabolism Screening Uncovers Regulatory Effects on the STING Immune Response in Mevalonate, Eicosanoid and Fatty Acid Pathways

Abstract

The cGAS/STING pathway is a critical signaling hub that orchestrates type I interferon (IFN) responses, autophagy, and programmed cell death in response to double-stranded DNA (dsDNA) or cyclic dinucleotides. While traditionally characterized as a sensor of foreign or mis-localized self dsDNA, recent evidence demonstrates that STING also integrates information about the homeostasis of cellular lipid biosynthesis into the innate inflammatory response. This integration occurs most notably through STINGs sensitivity to de novo cholesterol synthesis. However, given that mammalian cells undergo widespread lipid metabolic reprogramming, characterized by alterations in the synthesis of many lipid species in addition to cholesterol, during processes such as malignant transformation to cancer or during infection by intracellular pathogens, we hypothesized that STING function may be regulated by perturbations in other undescribed lipid pathways. To investigate potential other facets of the STING-lipid interface, we have performed a targeted small molecule screen across multiple lipid metabolic pathways, including the mevalonate, PPAR (fatty acid), and arachidonic acid pathways. Our findings reveal that positively and negatively perturbing enzymes within these diverse lipid paths including lipoxygenases and cyclooxygenases can significantly modulate STING-dependent signal transduction and transcriptional programs, identifying metabolic nodes that link lipid homeostasis with innate immune signaling. These results suggest that existing lipid-lowering and metabolic therapies may have unappreciated immunomodulatory effects on STING applicable in cancer and infectious disease, offering new opportunities for therapeutic intervention.