Putrescine alters the composition of interstitial dendritic cell subsets by suppressing Cybb-dependent oxidative...

Putrescine, a core polyamine, is closely linked to intestinal immune homeostasis and the pathogenesis of intestinal disease, yet its role in shaping dendritic cell (DC) subset differentiation in the intestinal lamina propria and the mechanism behind it remains undefined. Here, we first performed integrated analysis of seven public human single-cell RNA sequencing datasets to profile dendritic cell subsets across colorectal cancer tissues with varied MMR phenotypes. We fed mice a 1% (w/v) putrescine diet to raise intestinal putrescine levels and examined the effects on lamina propria DC subsets using flow cytometry, single-cell RNA sequencing, transcriptomics, and O2K-based metabolic assays. Elevated putrescine expanded the cDC1 subset (CD103⁺CD11b^-CD172a^-), contracted the cDC2 subsets (CD103^-CD11b⁺CD172a⁺ and CD103⁺CD11b⁺CD172a⁺), and reduced surface expression of CD11b and CD172a on lamina propria DCs. Single-cell and transcriptomic profiling showed that putrescine reshaped the transcriptional landscape of DC subsets, with marked downregulation of reactive oxygen species (ROS) and oxidative phosphorylation (OXPHOS) pathways. O2K metabolic analysis confirmed that putrescine lowered ROS output and oxygen consumption rate across several mitochondrial respiratory states, including basal and ATP-coupled respiration, while western blotting showed reduced Cybb expression in lamina propria DCs. Together, these findings indicate that putrescine reshapes intestinal lamina propria DC subset composition by suppressing Cybb, thereby limiting ROS production and OXPHOS activity. This work offers new mechanistic insight into how polyamine metabolism governs intestinal immune homeostasis and points to potential therapeutic targets for intestinal disorders such as colorectal cancer and inflammatory bowel disease.