A JAK-STAT-activated myeloid hub at ulceration sites underlies resistance to anti-TNF therapy in Crohn's disease

Despite major advances in immunotherapies, durable disease control in immune-mediated inflammatory diseases (IMIDs) is frequently limited by resistance driven by maladaptive immune programs, resulting in progressive tissue damage. Myeloid cells are central effectors across IMIDs, including inflammatory bowel disease (IBD), yet how discrete myeloid states govern disease progression and therapeutic response remains incompletely defined. Here, using integrative single-cell transcriptomic and molecular analyses of inflamed human ileum in Crohns disease (CD), we identify combinatorial transcriptional programs that revealed previously unrecognized axes of monocyte-macrophage (mo-mac) heterogeneity. These myeloid states and programs were conserved and validated across multiple independent cohorts. We delineate a pathogenic mo-mac subset, interferon-associated inflammatory monocytes (IFIM), shaped by convergent NF-{kappa}B and IFN{gamma} signaling and enriched in advanced disease. Baseline abundance of IFIM programs predicted resistance to anti-TNF therapy and severe postoperative recurrence, with IFIM-derived ligands sustaining epithelial injury. IFIM exhibited robust JAK-STAT activation, indicating susceptibility to JAK inhibition with clinically approved agents, including upadacitinib. Exemplified by IFIM-driven inflammation, these findings identify pathogenic myeloid state remodeling as a molecular basis of anti-TNF resistance and provide a framework for mechanism-guided therapeutic strategies across chronic inflammatory diseases.