GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE344nnn/GSE344153/primaryOK200TranscriptomicsCaenorhabditis elegansExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE344153GEOGSEfalseIntestinal lipid metabolism controls molecular and behavioral immunity through NHR-68 and gut–brain signaling in C. elegansAnimals must allocate limited energetic resources across competing defense programs in response to infection. Here, we show that the conserved nuclear hormone receptor NHR-68 integrates fatty acid metabolism with the neural control of molecular and behavioral immunity in Caenorhabditis elegans. Acting in parallel with NHR-10, NHR-68 controls genes involved in polyunsaturated fatty acid (PUFA) metabolism. Loss of NHR-68 disrupts linoleic acid (LA) homeostasis, impairing pathogen avoidance behavior. Supplementation with LA restores avoidance, and fat-3 inhibition, which elevates LA, enhances pathogen avoidance, whereas loss of LA synthesis by fat-2 inhibition diminishes this behavior, indicating that LA promotes behavioral immunity. We further show that NHR-68 acts in the intestine to regulate linoleic acid homeostasis, and that changes in intestinal lipid metabolism influence an AWC-dependent pathogen-avoidance circuit through intestine-to-neuron communication. NHR-68 suppresses activation of the PMK-1/p38 MAPK and DAF-16/FOXO pathways, which mediate molecular immune responses. These findings identify a gut-brain transcriptional circuit that connects intestinal lipid metabolism to neural and immune outputs, revealing a mechanism by which the metabolic state coordinates behavioral and molecular defenses to optimize host protection.2026/09/14GSE344153GSM9971489GSM9971487GSM9971488GSM9971485GSM9971486GSM9971483GSM9971494GSM9971484GSM9971492GSM9971493GSM9971490GSM997149137393344153Caenorhabditis elegans