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:We inflicted TBI to chemokine-deficient mouse lines in order to establish involvement of various signalling pathways that may be addressed therapeutically. Interacting chemokine pathways in brain regulate distinct inflammatory cells. Activated microglia are separate from invading phagocytes and dendritic cells. Findings show potential targets to interfere with specific inflammatory responses after brain injury. TBI was carried out in Ccl3-/- and Ccr2-/- mice, total RNA prepared from injured cerebral neocortex after three days. RNA samples were from uninjured Ccl3-/- and Ccr2-/- mice as reference for hybridization on Affymetrix microarrays.
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: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:We inflicted TBI to chemokine-deficient mouse lines in order to establish involvement of various signalling pathways that may be addressed therapeutically. Interacting chemokine pathways in brain regulate distinct inflammatory cells. Activated microglia are separate from invading phagocytes and dendritic cells. Findings show potential targets to interfere with specific inflammatory responses after brain injury.
Project description:In autoimmune diseases, accumulation of activated leukocytes correlates with inflammation and disease progression, and therefore, disruption of leukocyte trafficking is an active area of research. The protein kinase Tpl2 (MAP3K8) regulates leukocyte inflammatory responses and is also being investigated for therapeutic inhibition during autoimmunity. Herein, we addressed the contribution of Tpl2 to the regulation of macrophage chemokine and chemokine receptor expression and subsequent migration in vivo using a mouse model of Tpl2 ablation. We found that gene expression of the chemokine ligands CCL2, CCL7, CXCL2, and CXCL3 as well as the chemokine receptors CCR1 and CCR5 were reduced in macrophages from the bone marrow and peritoneal cavities of tpl2-/- mice following stimulation with LPS. LPS stimulation repressed chemokine receptor expression of CCR1, CCR2 and CCR5. Notably, LPS-induced repression of CCR1 and CCR5 was significantly enhanced in Tpl2-deficient macrophages and was observed to be dependent upon Erk activation and independent of PI3K and mTOR signaling. Consistent with alterations in chemokine and chemokine receptor expression, tpl2-/- macrophages were defective in trafficking to the peritoneal cavity following thioglycollate-induced inflammation. Overall, this study demonstrates a Tpl2-dependent mechanism for macrophage expression of both chemokine receptors and their ligands and provides further insight into how Tpl2 inhibition may disrupt inflammatory networks in vivo. microarray was used to profile the genome-wide expression patterns in Tpl2 wild-type and deficient macrophage.
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.
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:C-C chemokine ligand 2 (CCL2) plays pivotal roles in tumor formation, progression, and metastasis. Although CCL2 expression has been found to be dependent on the nuclear factor (NF)–κB signaling pathway, the regulation of CCL2 production in tumor cells has remained unclear. Mammalian target of rapamycin complex 1 (mTORC1) is a protein kinase that is activated in various tumor cell types. We have now identified a noncanonical pathway for regulation of CCL2 production that is mediated by mTORC1 but independent of NF-κB. Multiple phosphoproteomics approaches identified the transcription factor forkhead box K1 (FOXK1) as a downstream target of mTORC1, with dephosphorylation of FOXK1 in response to mTORC1 activation resulting in transactivation of the CCL2 gene. Inhibition of the mTORC1-FOXK1 axis attenuated insulin-induced CCL2 production as well as the accumulation of tumor-associated monocytes-macrophages and tumor progression in mice. Our results suggest that FOXK1 directly links mTORC1 signaling and CCL2 expression in a manner independent of NF-κB, and that CCL2 produced by this pathway contributes to tumor progression. Specific inhibition of FOXK1 may thus be a potential therapeutic strategy for cancer.