Project description:Leukocyte recruitment, a universal feature of tissue inflammation, is regulated by the interactions of chemokines with their G protein-coupled receptors. Activation of CC chemokine receptor 2 (CCR2) by its cognate chemokine ligands, including CCL2, plays a central role in recruitment of monocytes in several inflammatory diseases. In this study, we used phosphoproteomics to enable unbiased characterization of the signaling network resulting from CCL2 activation of CCR2. Using data-independent acquisition (DIA) mass spectrometry, both the proteome and phosphoproteome were quantified for FlpIn-HEK293T cells stably expressing CCR2, at six time points after activation with CCL2, in comparison with untreated cells. Differential expression analysis identified 699 significantly regulated phosphorylation sites located on 441 proteins. As expected, many of these proteins participate in canonical signal transduction pathways and the regulation of actin cytoskeleton dynamics, including numerous guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). In addition, we identified regulated phosphorylation sites in numerous proteins that exert functions in the nucleus, including several constituents of the nuclear pore complex. This study provides an unprecedented level of detail about CCR2 signalling and identifies potential novel targets for regulation of CCR2 function.
Project description:Chemotherapy offers long-term clinical benefits to many cancer patients. However, several pre-clinical studies have demonstrated that certain cytotoxic drugs enhance metastasis via multiple mechanisms. These studies have mainly focused on tumor cell-derived inflammation. The importance of host responses triggered by chemotherapy in regulating cancer metastasis has not been fully explored. Our recent studies have showed that multi-dose Gemcitabine (GEM) treatment promoted breast cancer lung metastasis in a transgenic spontaneous breast cancer animal model. Both CCR2+ macrophages and monocytes were increased in the lungs of GEM-treated mice. Further, the increase of CCR2+ macrophages and monocytes were observed in naïve (tumor-free) mice after GEM treatment. These changes were largely caused by chemotherapy-induced reactive myelopoiesis that are biased toward monocyte development. Importantly, the host responses following chemotherapy promote tumor metastasis, which is dependent on CCL2/CCR2 axis. To understand how lung macrophages contribute to the pro-metastatic effect of chemotherapy, the expression profile of lung interstitial macrophages (IMs) from GEM treated and PBS control tumor-free mice was examined.
Project description:Primary Graft Dysfunction (PGD) is the predominant cause of early graft loss following lung transplantation. We recently demonstrated that donor pulmonary intravascular non-classical monocytes (NCM) initiate neutrophil recruitment. Simultaneously, host-origin classical monocytes (CM) are mobilized from the spleen and, upon entry into the allograft, permeabilize the vascular endothelium to allow neutrophil extravasation necessary for PGD. Here, we show that CCL2-CCR2 axis is necessary for CM recruitment. Surprisingly, although intravital imaging and multichannel flow cytometry revealed that pharmacological or genetic depletion of donor NCM abrogated CM recruitment, single-cell RNAseq identified donor alveolar macrophages (AM) as predominant CCL2 secretors. Unbiased transcriptomic analysis of human and murine tissues combined with murine knockouts and chimeras indicated that while IL1β was secreted by multiple cell lineages, donor NCM were responsible for the early activation of AM and CCL2 release. IL1β production by NCM was NLRP3 inflammasome-dependent and inhibited by donor treatment using a clinically approved sulphonylurea, Glyburide. Production of CCL2 in the donor AM occurred through IL1R-dependent activation of PKC and NFκB-pathway. Accordingly, we show that IL1β-dependent paracrine interaction between donor NCM and AM leads to recruitment of host AM necessary for PGD. Since depletion of donor NCM, IL1β or IL1R antagonism, and inflammasome inhibition, abrogated recruitment of CM as well as PGD and are feasible using FDA-approved compounds, our findings have potential for immediate clinical translation.
Project description:Muscle injury triggers inflammation in which infiltrating mononuclear phagocytes are crucial for tissue regeneration. The interaction of the CCL2/CCR2 and CX3CL1/CX3CR1 chemokine axis that guides phagocyte infiltration is incompletely understood. Here, we show that CX3CR1 deficiency promotes muscle repair and rescues Ccl2-/- mice from impaired muscle regeneration as a result of altered macrophage function, not infiltration. Transcriptomic analysis of muscle mononuclear phagocytes reveals that Apolipoprotein E (ApoE) is up-regulated in mice with efficient regeneration. ApoE treatment enhances phagocytosis by mononuclear phagocytes in vitro, and restores phagocytic activity and muscle regeneration in Ccl2-/- mice. Because CX3CR1 deficiency may compensate for defective CCL2-dependant monocyte recruitment by modulating ApoE-dependent macrophage phagocytic activity, targeting CX3CR1 expressed by macrophages might be a powerful therapeutic approach to improve muscle regeneration.
Project description:A number of inhibitors of chemokine CCL2 and its receptor CCR2 are in development and may find application for treating a range of inflammatory conditions, including autoimmune and viral arthritides. Herein we sought to determine the effect of CCR2 deficiency on arthritis caused by an arthritogenic alphavirus, Chikungunya virus. Chikungunya virus (LR2006-OPY1) was injected subcutaneously into the hind foot of either CCR2 knockout or wild-type control mice (n=4-6). At day 0 and d7 post infection, RNA from the feet was harvested, the RNA was pooled (4-6 feet per time point per mouse strain) and gene expression analysis was performed using Mouse Gene ST arrays (Affymetrix).
Project description:Inflammatory monocytes (iMO) migrate from the bone marrow to the brain during viral encephalitis. For many viruses, including Herpes simplex virus type-1 (HSV), iMO recruitment is dependent on the chemokine receptor CCR2. However, La Crosse virus (LACV) induces iMO recruitment independent of CCR2. Comparison of iMOs from HSV and LACV-infected mice showed higher expression of the g protein-coupled receptor CCR7 in LACV-induced iMOs. CCR2/CCR7 double knockout mice (DKO) had reduced iMO recruitment following LACV infection compared to CCR2 or CCR7 single knockout mice indicating that each receptor regulated iMO recruitment through complimentary roles. Thus, CCR7 is a novel, synergistic pathway to CCR2-induced iMO recruitment during virus infection. Interestingly, unlike HSV-recruited iMOs, LACV-recruited iMOs did not influence disease and had higher expression of proinflammatory and proapoptotic transcripts but reduced mitotic, phagocytic and phagolysosomal pathway transcripts. These findings indicate that virus-specific activation of iMOs may affect their survival, maturation and functional capabilities.
Project description:Gene-level transcriptome analysis of monocyte mRNA derived from mice that are genetically deficient of the Ccl2 gene or Ccr2 gene The CCL2/CCR2 chemokine axis is critical in monocytes mobilization and innate immunity. Although mice deficient in either gene manifest similar phenotype, such as reduced atherosclerosis, some biologic processes are disrupted in starkly different ways in these mice. We found in a Her2/neu driven mammary carcinoma model, the absence of Ccl2 inhibits tumor growth and prolongs survival, while genetic deletion of Ccr2 has the opposite effect. One of the postulated mechanisms is that Ccl2 and Ccr2 affect monocyte development in different manners. This experiment was designed to compare the whole transcriptome of monocytes that are deficient in either Ccl2 or Ccr2, with the hypothesis that differential development of these monocytes will manifest as differential gene expression profiles.
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:A key unknown of the functional space in tumor immunity is whether physiologically relevant cancer antigen presentation occurs solely in draining lymph nodes versus tumors. Professional antigen presenting cells, i.e. the dendritic cells, are scarce and immature within tumors, greatly outnumbered by MHCII expressing non-hematopoietic cells, such as antigen-presenting cancer-associated fibroblasts (apCAFs). We hypothesized that after their exit from tumor-draining lymph nodes T cells depend on a second wave of antigen presentation provided in situ by structural cells. We show that dense apCAF regions in human lung tumors define hot immunological spots with increased numbers of CD4 T cells. The transcriptomic profile of human lung apCAFs aligned to that of pancreatic apCAFs across mice and humans and were both enriched for alveolar type II genes, suggesting an epithelial origin. Mechanistically, human apCAFs directly activated the TCRs of adjacent effector CD4 T cells and at the same time produced high levels of c1q, which acted on surface c1qbp on T cells to rescue them from apoptosis. Fibroblast-specific deletion of MHCII in mice impaired local MHCII immunity and accelerated tumor growth, while inducing c1qbp overexpression in adoptively transferred T cells expanded their numbers within tumors and reduced tumour burden. Collectively, our work shows that tumor T cell immunity post lymph node exit requires peripheral antigen presentation by a subset of CAFs and proposes a new conceptual framework upon which effective cancer immunotherapies can be built.
Project description:A key unknown of the functional space in tumor immunity is whether physiologically relevant cancer antigen presentation occurs solely in draining lymph nodes versus tumors. Professional antigen presenting cells, i.e. the dendritic cells, are scarce and immature within tumors, greatly outnumbered by MHCII expressing non-hematopoietic cells, such as antigen-presenting cancer-associated fibroblasts (apCAFs). We hypothesized that after their exit from tumor-draining lymph nodes T cells depend on a second wave of antigen presentation provided in situ by structural cells. We show that dense apCAF regions in human lung tumors define hot immunological spots with increased numbers of CD4 T cells. The transcriptomic profile of human lung apCAFs aligned to that of pancreatic apCAFs across mice and humans and were both enriched for alveolar type II genes, suggesting an epithelial origin. Mechanistically, human apCAFs directly activated the TCRs of adjacent effector CD4 T cells and at the same time produced high levels of c1q, which acted on surface c1qbp on T cells to rescue them from apoptosis. Fibroblast-specific deletion of MHCII in mice impaired local MHCII immunity and accelerated tumor growth, while inducing c1qbp overexpression in adoptively transferred T cells expanded their numbers within tumors and reduced tumour burden. Collectively, our work shows that tumor T cell immunity post lymph node exit requires peripheral antigen presentation by a subset of CAFs and proposes a new conceptual framework upon which effective cancer immunotherapies can be built.