AI Insight
This study reveals that the nuclear hormone receptor NHR-68 in C. elegans worms coordinates intestinal fatty acid metabolism with both behavioral and molecular immune responses. The researchers found that NHR-68 regulates linoleic acid levels in the gut, which influences pathogen avoidance behavior through gut-brain signaling pathways involving AWC neurons, while also modulating immune defense pathways including PMK-1/p38 MAPK and DAF-16/FOXO. This demonstrates a mechanism by which animals integrate their metabolic state with defensive strategies, allowing them to allocate limited energy resources between different types of immunity.
Why it matters
The discovery of this gut-brain metabolic circuit provides insight into how organisms coordinate multiple defense systems in response to infection, which could inform therapeutic approaches for infectious diseases and metabolic disorders. Understanding how lipid metabolism influences both immune function and behavior may lead to novel interventions that leverage dietary fatty acids to enhance host defense mechanisms.
Understand the Science
by Jie Ren, Yu Sang, Young-Mo Kim, Ernesto S. Nakayasu, Alejandro Aballay
Animals 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.