Microbial Energy Metabolism Fuels a CSF2-dependent Intestinal Macrophage Niche within Tertiary Lymphoid Organs

Maintaining intestinal macrophage (MP) heterogeneity is critical to ensure tissue homeostasis and host defense. The gut microbiota and host factors are thought to synergistically shape colonic MP development, although there remains a fundamental gap in our understanding of the details of such collaboration. Here, we report tertiary lymphoid organs (TLOs), enriched in group 3 innate lymphoid cells (ILC3s), as a microbiota-operated intestinal niche for the development of monocyte-derived MPs. ILC3-derived colony stimulating factor 2 (CSF2) serves as a developmental and functional determinant for MPs and required microbe-derived extracellular adenosine 5’-triphosphate (ATP) as a trigger. Microbial communities rich in extracellular ATP promoted MP turnover via ILC3 activity in an NLRP3-dependent fashion. Single cell RNA-sequencing of MPs revealed unique TLO-associated, CSF2-dependent MP populations critical for anti-microbial defense against enteric infection. Collectively, these findings describe a fundamental framework that constitutes an intestinal MP niche fueled by microbial energy metabolism. ### Competing Interest Statement The authors have declared no competing interest.