Subject(s)
COVID-19 , Sepsis , Humans , Blood Platelets , Signaling Lymphocytic Activation Molecule FamilyABSTRACT
Macrophages regulate protective immune responses to infectious microbes, but aberrant macrophage activation frequently drives pathological inflammation. To identify regulators of vigorous macrophage activation, we analyzed RNA-seq data from synovial macrophages and identified SLAMF7 as a receptor associated with a superactivated macrophage state in rheumatoid arthritis. We implicated IFN-γ as a key regulator of SLAMF7 expression and engaging SLAMF7 drove a strong wave of inflammatory cytokine expression. Induction of TNF-α after SLAMF7 engagement amplified inflammation through an autocrine signaling loop. We observed SLAMF7-induced gene programs not only in macrophages from rheumatoid arthritis patients but also in gut macrophages from patients with active Crohn's disease and in lung macrophages from patients with severe COVID-19. This suggests a central role for SLAMF7 in macrophage superactivation with broad implications in human disease pathology.
Subject(s)
Inflammation/immunology , Macrophage Activation/immunology , Signaling Lymphocytic Activation Molecule Family/immunology , Transcriptome/immunology , Acute Disease , Adult , Arthritis, Rheumatoid/genetics , Arthritis, Rheumatoid/immunology , Arthritis, Rheumatoid/metabolism , COVID-19/genetics , COVID-19/immunology , COVID-19/metabolism , COVID-19/virology , Cells, Cultured , Chronic Disease , Crohn Disease/genetics , Crohn Disease/immunology , Crohn Disease/metabolism , Female , Humans , Inflammation/genetics , Inflammation/metabolism , Macrophage Activation/genetics , RNA-Seq/methods , Reverse Transcriptase Polymerase Chain Reaction/methods , SARS-CoV-2/immunology , SARS-CoV-2/physiology , Signaling Lymphocytic Activation Molecule Family/genetics , Signaling Lymphocytic Activation Molecule Family/metabolism , Single-Cell Analysis/methods , Synovial Membrane/immunology , Synovial Membrane/metabolism , Synovial Membrane/pathology , Transcriptome/geneticsABSTRACT
Myeloid-derived suppressor cells (MDSCs) are innate immune cells that acquire the capacity to suppress adaptive immune responses during cancer. It remains elusive how MDSCs differ from their normal myeloid counterparts, which limits our ability to specifically detect and therapeutically target MDSCs during cancer. Here, we sought to determine the molecular features of breast cancer-associated MDSCs using the widely studied mouse model based on the mouse mammary tumor virus (MMTV) promoter-driven expression of the polyomavirus middle T oncoprotein (MMTV-PyMT). To identify MDSCs in an unbiased manner, we used single-cell RNA sequencing to compare MDSC-containing splenic myeloid cells from breast tumor-bearing mice with wild-type controls. Our computational analysis of 14,646 single-cell transcriptomes revealed that MDSCs emerge through an aberrant neutrophil maturation trajectory in the spleen that confers them an immunosuppressive cell state. We establish the MDSC-specific gene signature and identify CD84 as a surface marker for improved detection and enrichment of MDSCs in breast cancers.