AcNR1F orchestrates epidermal remodeling to enable host adaptation in Angiostrongylus cantonensis.

Nuclear receptor NR1F regulates circadian rhythms in mammals, metamorphosis in insects, and molting in free-living Caenorhabditis elegans; however, its role in parasitic nematode development remains elusive. Angiostrongylus cantonensis, a zoonotic pathogen that causes eosinophilic meningitis in humans, exhibits distinct host adaptation, with mice and most mammals serving as non-permissive hosts and rats as the permissive host. We combined multi-omic analyses, lentivirus-mediated RNAi, LC-MS/MS, and dual-luciferase assays to elucidate AcNR1F functions in development and host adaptation. Acnr1f was expressed in the intestine, uterus, and seminal vesicle by in situ hybridization. Acnr1f showed high expression in L5 larvae and adults but low expression in L1-L4 larvae. Acnr1f expression was significantly higher in worms derived from rats than from mice; approximately 25% of co-expressed genes (918) were identified as potential downstream targets that may be integrated to regulate parasitic adaptation. RNAi reduced Acnr1f transcripts by 38.11% in female adults, resulting in significantly decreased recovery of L4 and L5 larvae and adults, a 64% reduction in egg production, and abnormal eggs with low hatching rate. Histological and ultrastructural analyses revealed thinned cuticle, reduced collagen fibers, and disrupted epidermal integrity. Transcriptomic analysis showed that differentially expressed genes were enriched in structural constituent of cuticle, metalloendopeptidase activity, extracellular matrix structural constituent. Dual-luciferase assays showed that the down-regulated collagen genes col-12 and col-144 were direct AcNR1F targets (>300-fold and >40-fold induction, respectively). Differential levels of cholesterol, corticosterone, and 7α,25-dihydroxycholesterol between worms from rats and mice were identified as AcNR1F ligands by LC-MS/MS and ligand-binding assays. Thus, AcNR1F is a ligand-activated nuclear receptor that directly regulates target genes to influence development and reproduction of A. cantonensis. The distinct availability of host-derived ligands and differential AcNR1F expressive level between worms from rodents highlights this receptor as a critical molecular switch for parasitic adaptation, providing mechanistic insights into host-pathogen interactions.