Project description:The interactions between chemokines and their receptors, particularly in the context of inflammation, are complex with individual receptors binding multiple ligands and individual ligands interacting with multiple receptors. In addition, there are numerous reports of simultaneous co-expression of multiple inflammatory chemokine receptors on individual inflammatory leukocyte subtypes. Overall, this has previously been interpreted as redundancy and proposed as a protective mechanism to ensure that the inflammatory response is robust. In contrast we have hypothesised that the system is not redundant but exquisitely subtle. Our interests relate to the receptors CCR1, CCR2, CCR3 and CCR5 which, together, regulate non-neutrophilic myeloid cell recruitment to inflammatory sites. Here we demonstrate that, whilst most murine monocytes exclusively express CCR2, there is a small subpopulation, which is expanded during inflammation, which co-expresses CCR1 and CCR2. Combinations of transcript and functional analysis demonstrate that this is not redundant expression and that co-expression of CCR1 and CCR2 marks a phenotypically distinct population of monocytes characterised by expression of genes otherwise typically associated with neutrophils. Single cell RNA sequencing confirms this as a monodisperse population of atypical monocytes. This monocytic population has been previously described as having immunosuppressive activity. Overall, our data confirm combinatorial chemokine receptor expression by a subpopulation of monocytes but demonstrate that this is not redundant expression and marks a discrete monocytic population.
Project description:The interactions between chemokines and their receptors, particularly in the context of inflammation, are complex with individual receptors binding multiple ligands and individual ligands interacting with multiple receptors. In addition, there are numerous reports of simultaneous co-expression of multiple inflammatory chemokine receptors on individual inflammatory leukocyte subtypes. Overall, this has previously been interpreted as redundancy and proposed as a protective mechanism to ensure that the inflammatory response is robust. In contrast we have hypothesised that the system is not redundant but exquisitely subtle. Our interests relate to the receptors CCR1, CCR2, CCR3 and CCR5 which, together, regulate non-neutrophilic myeloid cell recruitment to inflammatory sites. Here we demonstrate that, whilst most murine monocytes exclusively express CCR2, there is a small subpopulation, which is expanded during inflammation, which co-expresses CCR1 and CCR2. Combinations of transcript and functional analysis demonstrate that this is not redundant expression and that co-expression of CCR1 and CCR2 marks a phenotypically distinct population of monocytes characterised by expression of genes otherwise typically associated with neutrophils. Single cell RNA sequencing confirms this as a monodisperse population of atypical monocytes. This monocytic population has been previously described as having immunosuppressive activity. Overall, our data confirm combinatorial chemokine receptor expression by a subpopulation of monocytes but demonstrate that this is not redundant expression and marks a discrete monocytic population.
Project description:Monocytes have been categorized in three main subpopulations based on CD14 and CD16 surface expression. Classical monocytes are the most abundant subset in the blood. They express a CD14+CD16-CCR2+ phenotype, which confers on them the ability to migrate to inflammatory sites by quickly responding to CCL2 signaling. Here we identified and characterized the surge and expansion of a novel monocyte subset during SIV and HIV infection. They were undistinguishable from classical monocytes regarding CD14 and CD16 expression, but did not express surface CCR2. Transcriptome analysis of sorted cells confirmed that they represent a distinct subpopulation that expresses lower levels of inflammatory cytokines and activation markers than their CCR2+ counterparts. They exhibited impaired phagocytosis and deficient chemotaxis in response to CCL2 and CCL7, besides being refractory to SIV infection. We named these cells atypical CCR2- classical (ACC) monocytes, and believe they play an important role in AIDS pathogenesis, possibly reflecting an anti-inflammatory response against the extreme immune activation observed during SIV and HIV infection. Antiretroviral therapy caused this population to decline in both macaque and human subjects, suggesting that this atypical phenotype may be induced by viral replication. Expression profiling by NanoString nCounter gene expression system. Classical monocytes (CD14++CD16-) from six SIV-infected macaques (day 14 post inoculation) were sorted in two groups according to CCR2 expression.
Project description:Comparative analysis of FACS-sorted CCR2- and CCR2+ HSC in the steady state. CCR2+ HSC have fourfold higher proliferative rates than CCR2- HSC, are are biased towards the myeloid lineage and dominate the migratory HSC population. Comparison of pooled CCR2- and CCR2+ HSC (bone marrow from 20 mice pooled for each sample), three biological replicates each.
Project description:Regulation of carotenoid composition and shoot branching in Arabidopsis by a chromatin modifying histone methyltransferase, SDG8<br>Comparison of transcript profiles between wild type Columbia and ccr1 (carotenoid and chloroplast regulatory) mutant, which contains a mutation in At1g77300 (SDG8)
Project description:Immunotherapy approaches have been ineffective in pancreatic ductal adenocarcinoma (PDA), pointing to the need for additional avenues to target in the pancreatic cancer microenvironment. We previously discovered that tumor educated bone marrow derived macrophages express high levels of C-C Motif Chemokine Receptor 1 (CCR1). By single-cell RNA sequencing, we found CCR1 to be expressed predominantly by tumor associated macrophages (TAMs) and granulocytes in both human and mouse PDA. Thus, we sought to investigate the functional role of CCR1 in pancreatic cancer. Using KC; Ccr1-/- mice (Ptf1a-Cre; LSL-KrasG12D; Ccr1-/-), we determined that CCR1 is dispensable during pancreatic cancer initiation, although we observed increased CD8 T cell infiltration in KC; Ccr1-/- pancreata. Using syngeneic orthotopic PDA mouse models we discovered that CCR1 ablation in Ccr1-/- mice or pharmaceutical inhibition of CCR1 both resulted in reduced tumor growth. Further, CCR1 ablation prolonged the overall survival of KPC mice. Through mass cytometry (CyTOF) and co-immunofluorescence staining we showed CCR1 ablation elevated CD8 T cell cytotoxic activity in the orthotopic PDA model. Mechanistically we found TAMs lacking CCR1 expressed less Arginase 1 and CD206 -both immunosuppressive markers of macrophages- compared to wild type TAMs. Further, targeting both CCR1 and Arginase 1 synergized with immune checkpoint blockade anti-PD-L1 to enhance antitumor efficacy in orthotopic model of PDA. Together, our data is consistent with the notion that tumor associated macrophages lacking CCR1 expression are less immunosuppressive, consequently allowing increased CD8 T cell mediated anti-tumor immunity. Targeting CCR1 in combination with immune checkpoint blockade improves antitumor efficacy in pancreatic cancer.
Project description:Comparative analysis of FACS-sorted CCR2- and CCR2+ HSC in the steady state. CCR2+ HSC have fourfold higher proliferative rates than CCR2- HSC, are are biased towards the myeloid lineage and dominate the migratory HSC population.