Project description:Interactions between intracellular bacteria and mononuclear phagocytes give rise to diverse cellular phenotypes that may determine the outcome of infection. Recent advances in single-cell RNA-seq (scRNA-seq) have identified multiple subsets within the mononuclear population, but implications to their function during infection remain unknown. Here, we applied microscopy, flow cytometry and scRNA-seq to survey the mononuclear niche of intracellular Salmonella Typhimurium (S.Tm) during early systemic infection in mice. We describe eclipse-like growth kinetics in the spleen, with a first phase of bacterial control mediated by tissue-resident red-pulp macrophages. A second phase involved extensive bacterial replication within a newly identified macrophage population characterized by CD9 expression. Using Nr4a1e2-/- mice we established that CD9+ macrophages originated from non-classical monocytes (NCM), and NCM-depleted mice were more resistant to S.Tm infection. Our study defines a novel host-pathogen interface, with macrophage subset-specific interactions that determines early infection dynamics and the infection outcome of the entire organism.
Project description:Interactions between intracellular bacteria and mononuclear phagocytes give rise to diverse cellular phenotypes that may determine the outcome of infection. Recent advances in single-cell RNA-seq (scRNA-seq) have identified multiple subsets within the mononuclear population, but implications to their function during infection remain unknown. Here, we applied microscopy, flow cytometry and scRNA-seq to survey the mononuclear niche of intracellular Salmonella Typhimurium (S.Tm) during early systemic infection in mice. We describe eclipse-like growth kinetics in the spleen, with a first phase of bacterial control mediated by tissue-resident red-pulp macrophages. A second phase involved extensive bacterial replication within a newly identified macrophage population characterized by CD9 expression. Using Nr4a1e2-/- mice we established that CD9+ macrophages originated from non-classical monocytes (NCM), and NCM-depleted mice were more resistant to S.Tm infection. Our study defines a novel host-pathogen interface, with macrophage subset-specific interactions that determines early infection dynamics and the infection outcome of the entire organism.
Project description:Interactions between intracellular bacteria and mononuclear phagocytes give rise to diverse cellular phenotypes that may determine the outcome of infection. Recent advances in single-cell RNA-seq (scRNA-seq) have identified multiple subsets within the mononuclear population, but implications to their function during infection remain unknown. Here, we applied microscopy, flow cytometry and scRNA-seq to survey the mononuclear niche of intracellular Salmonella Typhimurium (S.Tm) during early systemic infection in mice. We describe eclipse-like growth kinetics in the spleen, with a first phase of bacterial control mediated by tissue-resident red-pulp macrophages. A second phase involved extensive bacterial replication within a newly identified macrophage population characterized by CD9 expression. Using Nr4a1e2-/- mice we established that CD9+ macrophages originated from non-classical monocytes (NCM), and NCM-depleted mice were more resistant to S.Tm infection. Our study defines a novel host-pathogen interface, with macrophage subset-specific interactions that determines early infection dynamics and the infection outcome of the entire organism.
Project description:Interactions between intracellular bacteria and mononuclear phagocytes give rise to diverse cellular phenotypes that may determine the outcome of infection. Recent advances in single-cell RNA sequencing (scRNA-seq) have identified multiple subsets within the mononuclear population, but implications to their function during infection are limited. Here, we surveyed the mononuclear niche of intracellular Salmonella Typhimurium (S.Tm) during early systemic infection in mice. We described eclipse-like growth kinetics in the spleen, with a first phase of bacterial control mediated by tissue-resident red-pulp macrophages. A second phase involved extensive bacterial replication within a macrophage population characterized by CD9 expression. We demonstrated that CD9+ macrophages induced pathways for detoxificating oxidized lipids, that may be utilized by intracellular S.Tm. We established that CD9+ macrophages originated from non-classical monocytes (NCM), and NCM-depleted mice were more resistant to S.Tm infection. Our study defines macrophage subset-specific host-pathogen interactions that determine early infection dynamics and infection outcome of the entire organism.
Project description:The transcriptome of splenic classical dendritic cells (cDCs) (CD3- CD19- CD45+ MHC-II+ CD11c+) was compared in Wild Type (WT) mice, Germ Free (GF) mice and mice deficient for the Ifnar1 gene (IFNAR). Cells were isolated and sorted by flow cytometry to high purity. The cells were stimulated ex vivo with PBS or LPS. The results show remarkable similarities between the transcriptome of splenic cDCs in GF and IFNAR mice.
Project description:The new official nomenclature subdivides human monocytes into three subsets, classical (CD14++CD16-), intermediate (CD14++CD16+) and nonclassical (CD14+CD16+). Here, we comprehensively define relationships and unique characteristics of the three human monocyte subsets using microarray and flow cytometry analysis. Our analysis revealed that the intermediate and nonclassical monocyte subsets were most closely related. For the intermediate subset, majority of genes and surface markers were expressed at an intermediary level between the classical and nonclassical subset. There features therefore indicate a close and direct lineage relationship between the intermediate and nonclassical subset. From gene expression profiles, we define unique characteristics for each monocyte subset. Classical monocytes were functionally versatile, due to the expression of a wide range of sensing receptors and several members of the AP-1 transcription factor family. The intermediate subset was distinguished by high expression of MHC class II associated genes. The nonclassical subset were most highly differentiated and defined by genes involved in cytoskeleton rearrangement that explains their highly motile patrolling behavior in vivo. Additionally, we identify unique surface markers, CLEC4D, IL-13RA1 for classical, GFRA2, CLEC10A for intermediate and GPR44 for nonclassical. Our study hence defines the fundamental features of monocyte subsets necessary for future research on monocyte heterogeneity.