IL-1b+ tumor-associated macrophages fuel pathogenic inflammation in pancreatic cancer - Molecular Cartography of human PDAC samples

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with high resistance to therapy. Inflammatory and immunomodulatory signals co-exist in the tumor microenvironment (TME), leading to dysregulated reparative and cytotoxic responses. Tumor-associated macrophages (TAMs) control immune dynamics in the TME, but their heterogeneity and plasticity have hampered understanding of the underlying mechanisms. Here, we combined single-cell and spatial genomics with functional experiments to elucidate macrophage functions in PDAC. We uncovered an inflammatory loop between tumor cells and interleukin (IL)-1b+ TAMs, a subset of macrophages elicited by a local synergy between prostaglandin E2 (PGE2) and tumor necrosis factor (TNF)-a. Interfering with the PGE2-IL-1b axis elicited TAM reprogramming and antagonized tumor-intrinsic inflammation, leading to PDAC control in vivo. IL-1b+ TAMs are conserved across human cancers and correlate with inflammation and patient prognosis in a context-dependent manner. Our study highlights how TAMs govern between inflammation and immune suppression in cancer, with significant therapeutic implications. Spatial transcriptomics data obtained by Molecular Cartography (Resolve Biosciences) of tumor samples from human PDAC