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Bulk RNA-seq of CD11b+ cells from MC38 tumours in Kaede transgenic mice

ABSTRACT: Tumour-associated macrophages (TAMs) are a universal feature of cancers but variably influence outcome and treatment responses. Here, we used a photoconvertible mouse to distinguish newly entering, monocyte-derived (md)TAMs that were enriched at the tumour core, from resident-like (r)TAMs that localised with fibroblasts at the tumour–normal interface. The mdTAM pool was highly dynamic and continually replenished by circulating monocytes. Upon tumour entry, these monocytes differentiated down two divergent fate trajectories distinguished by the expression of MHC class II. MHC-II+ mdTAMs were functionally distinct from MHC-II– mdTAMs, demonstrating increased capacity for endocytosis and FcγR-mediated phagocytosis, as well as pro-inflammatory cytokine production. Both mdTAM subsets showed reduced expression of inflammatory transcripts and increased expression of PD-L1 with increasing tumour dwell-time. Treatment with anti-PD-L1 skewed mdTAM differentiation towards the MHC-II+ fate and attenuated the anti-inflammatory effects of the tumour environment. Anti-PD-L1 enhanced mdTAM–CD4+ T-cell interactions, establishing an IFNγ-CXCL9/10-dependent positive feedback loop. Altogether, these data resolve distinct temporal, spatial and functional properties of TAMs, and provide evidence of subset-specific effects of PD-L1 blockade.

ORGANISM(S): Mus musculus

PROVIDER: GSE298881 | GEO | 2025/06/07

REPOSITORIES: GEO

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Project description:Obesity is a leading risk factor for progression and metastasis of many cancers1,2, yet can also promote improved survival for some cancers3-5 and enhance responses to some immune checkpoint blockade therapies6-8. The role of the immune system in the obesity-cancer connection and how obesity influences immunotherapy, however, remain unclear. While PD-1 expression by macrophages has been described9-12, we found that obesity selectively induced PD-1 on macrophages and that PD-1 directly impaired macrophage function. Single cell RNA sequencing of murine colorectal carcinoma tumors showed obesity remodeled myeloid and T cell populations, with fewer clonally expanded effector T cells and increased abundance of PD-1+ tumor-associated macrophages (TAM). Cytokines and molecules associated with obesity, including IL-6, leptin, and insulin, and the unsaturated fatty acid palmitate, induced PD-1 expression on macrophages in a glycolysis-dependent manner and that MTORC1 pathway signaling is essential for PD1 expression. PD-1+ TAMs had increased mitochondrial respiration, fatty acid metabolism and cell cylewhile PD-1- TAMs had increased inflammatory signature , phagocytosis and antigen presentation to T cells. These patterns were directly regulated by PD-1, as recombinant PD-L1 reduced macrophage glycolysis, phagocytic capacity and antigen presentation, and this was reversed with blocking PD-1 antibody. Further, inhibition of glycolysis with 2-deoxyglucose prevented the increase in CD86, MHC-I and MHC-II that would otherwise occur with anti-PD-1 treatment. Conversely, PD-1-deficient Pdcd1-/- TAMs had high rates of glycolysis, phagocytosis, and expression of MHC-II. Myeloid-specific PD-1 deficiency correlated with slower tumor growth, enhanced TAM antigen presentation capability, and increased CD8 T cell activation together with reduced markers of exhaustion. These findings show metabolic signaling and type 1 inflammatory cues in obesity induces PD-1-mediated suppression of TAM function and reveal a unique macrophage-specific and glycolysis-dependent mechanism to modulate immune tumor surveillance and checkpoint blockade. This may contribute to increased cancer risk yet improved response to PD-1 blockade in TAM-enriched tumors and obesity.

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Bulk RNA-seq of CD11b+ cells from MC38 tumours in Kaede transgenic mice

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