Casanova-Acebes et al. characterized the tumor macrophage compartment in early-stage NSCLC lesions. ScRNAseq analysis showed tissue-resident macrophages (TRMs) were conserved in both human NSCLC and mouse lung tumors. In early-stage tumors, TRMs localized close to tumor cells, promoting EMT and potent Treg responses. As tumors grew, TRMs relocated to the TME periphery and were replaced by monocyte-derived macrophages in mouse and human tumors. Depleting TRMs before, but not after, tumors were established decreased Treg numbers, increased numbers of IFNγ+CD8+ T cells, and decreased tumor invasiveness and growth.

Contributed by Katherine Turner

ABSTRACT: Macrophages have a key role in shaping the tumour microenvironment (TME), tumour immunity and response to immunotherapy, which makes them an important target for cancer treatment(1,2). However, modulating macrophages has proved extremely difficult, as we still lack a complete understanding of the molecular and functional diversity of the tumour macrophage compartment. Macrophages arise from two distinct lineages. Tissue-resident macrophages self-renew locally, independent of adult haematopoiesis(3-5), whereas short-lived monocyte-derived macrophages arise from adult haematopoietic stem cells, and accumulate mostly in inflamed lesions(1). How these macrophage lineages contribute to the TME and cancer progression remains unclear. To explore the diversity of the macrophage compartment in human non-small cell lung carcinoma (NSCLC) lesions, here we performed single-cell RNA sequencing of tumour-associated leukocytes. We identified distinct populations of macrophages that were enriched in human and mouse lung tumours. Using lineage tracing, we discovered that these macrophage populations differ in origin and have a distinct temporal and spatial distribution in the TME. Tissue-resident macrophages accumulate close to tumour cells early during tumour formation to promote epithelial-mesenchymal transition and invasiveness in tumour cells, and they also induce a potent regulatory T cell response that protects tumour cells from adaptive immunity. Depletion of tissue-resident macrophages reduced the numbers and altered the phenotype of regulatory T cells, promoted the accumulation of CD8(+) T cells and reduced tumour invasiveness and growth. During tumour growth, tissue-resident macrophages became redistributed at the periphery of the TME, which becomes dominated by monocyte-derived macrophages in both mouse and human NSCLC. This study identifies the contribution of tissue-resident macrophages to early lung cancer and establishes them as a target for the prevention and treatment of early lung cancer lesions.

Author Info: (1) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. mcasanova@cnio.es. Precision Immunology Institute, Icahn School of Medicine at M

Author Info: (1) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. mcasanova@cnio.es. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. mcasanova@cnio.es. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. mcasanova@cnio.es. Cancer Immunity Laboratory, Molecular Oncology Program, Spanish National Cancer Centre, Madrid, Spain. mcasanova@cnio.es. (2) Division of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (3) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (4) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (5) Institut Curie, PSL Research University, INSERM U932, Paris, France. (6) Department of Cancer Immunology, Genentech, South San Francisco, CA, USA. (7) Department of Cancer Immunology, Genentech, South San Francisco, CA, USA. (8) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (9) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (10) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (11) The Ronald O. Perelman Department of Dermatology, New York University Grossman School of Medicine, New York, NY, USA. Experimental Therapies and Novel Biomarkers in Cancer, Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain. (12) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (13) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (14) Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (15) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (16) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria. (17) INSERM U1218 ACTION, University of Bordeaux, Bordeaux, France. (18) Microscopy CoRE, Dean's CoREs, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (19) The Ronald O. Perelman Department of Dermatology, New York University Grossman School of Medicine, New York, NY, USA. (20) Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (21) Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA. (22) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Division of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Institute of Thoracic Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (23) Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (24) Department of Cancer Immunology, Genentech, South San Francisco, CA, USA. (25) Institut Curie, PSL Research University, INSERM U932, Paris, France. (26) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Division of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (27) Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA. miriam.merad@mssm.edu. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. miriam.merad@mssm.edu. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. miriam.merad@mssm.edu. Human Immune Monitoring Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA. miriam.merad@mssm.edu.