Tracing NAD⁺ metabolism uncovers adaptive coordination between host and microbiome during colitis

Host-microbiota metabolic interactions critically regulate nicotinamide adenine dinucleotide (NAD+) homeostasis, and their disruption is increasingly linked to chronic diseases including inflammatory bowel disease (IBD). However, it remains unclear whether NAD+ dysregulation in IBD arises from impaired production, enhanced consumption, or both. Using multi-omics approaches and stable isotope-labeled NAD+ precursors administered via intravenous infusion in a murine model of dextran sulfate sodium (DSS)-induced colitis, we mapped tissue- and lumen-specific NAD+ metabolism under inflammatory stress. Our results reveal tissue-specific rewiring of NAD+ metabolism, with increased flux through the salvage pathway compensating for reduced de novo NAD+ synthesis from tryptophan. In parallel, microbial de novo NAD+ production was elevated, highlighting a cooperative host–microbiota response to inflammatory stress. These findings demonstrate differential regulation of NAD+ biosynthesis during acute colitis and underscore the dynamic interplay between host and microbial metabolism in maintaining NAD+ homeostasis under inflammatory conditions.