Intestinal stroma guides monocyte differentiation to macrophages through GM-CSF

Stroma provides tissues with structural integrity and organization, but its capacity to shape myeloid cells is poorly understood. Here we quantify stromal response to inflammation in pediatric inflammatory bowel disease (IBD) and reveal subset-specific inflammatory responses across colon segments and intestinal layers. Using data from a murine dynamic gut injury model and human ex vivo transcriptomic/protein/spatial analysis, we found that PDGFRA+CD142-/low fibroblasts and monocytes/macrophages co-localize in the intestine. Primary human fibroblast-monocyte co-cultures showed that intestinal PDGFRA+CD142-/low fibroblasts foster monocyte transition to CCR2+CD206+ macrophages through granulocyte-macrophage colony-stimulating factor (GM-CSF). Monocyte-derived CCR2+CD206+ cells from co-cultures had a phenotype similar to intestinal CCR2+CD206+ macrophages from newly diagnosed pediatric IBD patients, with higher levels of PD-L1 and lower levels of GM-CSF receptor. The study depicts subset-specific changes in stromal response to inflammation and demonstrates the stromal potential to guide intestinal macrophage differentiation. Bulk seq on FACS sorted intestinal stromal cells, three different populations (X1-X3).