Monocyte infiltration induces CNS arginine catabolism to fuel neuroinflammation

While tissue-specific Mdc reprogramming is well-established, how Mdc inflitration alters tissue metabolism remains unclear. Here, using a murine neuroinflammation model coupled with genetic fate-mapping, metabolomics, and metabolite imaging, we identify that central nervous system (CNS) Mdc infiltration is associated with substantial metabolic changes, assigning disease-linked metabolites (DLMs) therein.

Particularly, we found increased arginine catabolism driven by lesion-associated Arginase-1 (Arg1)-expressing Mdcs promoted oxidative damage, lipid accumulation and Mdc dysfunction. Genetic Arg1-deficiency within Mdcs during neuroinflammation increased extracellular arginine and was associated with rewiring of the CNS metabolic landscape, including attenuated DLMs. This was accompanied by enhanced Mdc-driven anti-inflammation, regulatory T cell expansion, and improved disease outcome.