Transcriptomic profiling of colonic epithelium and vascular endothelium compartments in aGVHD of colon. (A) Unsupervised heat map of epithelial compartment, with the 2 most different hierarchical clusters marked. Rows represent genes, and each column is an AOI. (B) Epithelial volcano plot shows differentially expressed genes pertaining to mature colon epithelium with basal function and with minimal inflammatory presence in EC1 and an obvious inflammatory, chemotactic signature with some evidence of stem cell genes (regenerative activity?) in EC2. (C) The inflamed EC2 niche is enriched in SR patients (Fisher exact test, ∗∗∗∗P < .0001). (D) The basal EC1 niche has more tissue with LG damage (Fisher exact test, ∗P < .0186). (E) Unsupervised heat map of endothelial compartment similarly shows 2 clusters with (F) vascular cluster 2 (VC2) differentially expressing inflammatory genes. VC1 is a basal-leaning signature with genes related to solute channels, lipid handling, and cell-matrix interactions, and some genes pertaining to neoangiogenesis. (G) Neither cluster is overrepresented in differing steroid response (Fisher exact test, P = .6032), but (H) the inflamed, VC2 vessels are increased in HG pathology areas (Fisher exact test, ∗P = .0350).