Project description:RNA was isolated from purified TAMs from MC-38 tumor-bearing mice after 24 hours of anti-MerTK single dose treatment at 30mg/kg body weight intravenously. The "SAMPLE_ID" sample characteristic is a sample identifier internal to Genentech. The ID of this project in Genentech's ExpressionPlot database is PRJ0014685
Project description:Tolerogenic dendritic cells (tol-DCs) offer a promising therapeutic potential for autoimmune diseases. Tol-DCs have been reported to inhibit immunogenic responses, yet little is known about the mechanisms controlling their tolerogenic status, as well as associated specific markers. Here we show that the anti-inflammatory TAM receptor tyrosine kinase MERTK, is highly expressed on clinical grade dexamethasone-induced human tol-DCs and mediates their tolerogenic effect. Neutralization of MERTK in allogenic mixed lymphocyte reactions as well as autologous DC-T cell cultures leads to increased T cell proliferation and IFN-g production. Additionally, we identify a previously unrecognized non-cell autonomous regulatory function of MERTK expressed on DCs. Recombinant Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK agonist Protein S (PROS1) expressed by T cells. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine pro-proliferative mechanism. Collectively, these results suggest that MERTK on tol-DCs directly inhibits T cell activation through the competition for PROS1 interaction with MERTK in the T cells. Targeting MERTK may provide an interesting approach to effectively increase or suppress tolerance for the purpose of immunotherapy. The complete database comprised the expression measurements of 54,675 genes for: immature (n=9), mature (n=7) and tolerogenic (n=8). Influence of treatment with dexamethasone (n=3) and LPS (n=2) are included.
Project description:We studied the impact of Ptdss1 knockdown in PyMT mouse mammary tumor cells and of Csf1-driven Mertk KO (macrophage-specfic) on tumor growth and the associated macrophage phenotype in an orthotopic tumor model. To gain insight into the reasons underlying tumor rejection once either Ptdss1 was deleted in tumor cells or Mertk was knocked out in macrophages, whole transcriptome profiling of FACS-sorted tumor-associated macrophages of WT or macrophage-specific Mertk KO mice receiving either control tumor cells or Ptdss1 knockdown tumor cells was performed via next generation mRNA sequencing, at least in triplicates, on a NextSeq 500 high-throughput bench top sequencer.
Project description:Tolerogenic dendritic cells (tol-DCs) offer a promising therapeutic potential for autoimmune diseases. Tol-DCs have been reported to inhibit immunogenic responses, yet little is known about the mechanisms controlling their tolerogenic status, as well as associated specific markers. Here we show that the anti-inflammatory TAM receptor tyrosine kinase MERTK, is highly expressed on clinical grade dexamethasone-induced human tol-DCs and mediates their tolerogenic effect. Neutralization of MERTK in allogenic mixed lymphocyte reactions as well as autologous DC-T cell cultures leads to increased T cell proliferation and IFN-g production. Additionally, we identify a previously unrecognized non-cell autonomous regulatory function of MERTK expressed on DCs. Recombinant Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK agonist Protein S (PROS1) expressed by T cells. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine pro-proliferative mechanism. Collectively, these results suggest that MERTK on tol-DCs directly inhibits T cell activation through the competition for PROS1 interaction with MERTK in the T cells. Targeting MERTK may provide an interesting approach to effectively increase or suppress tolerance for the purpose of immunotherapy.
Project description:Mononuclear phagocytes play an important role in the removal of apoptotic cells by expressing cell surface receptors that recognize and remove apoptotic cells. Based on the knowledge that cigarette smoking is associated with increased lung cell turnover, we hypothesized that alveolar macrophages (AM) of normal cigarette smokers may exhibit enhanced expression of apoptotic cell removal receptor genes. AM obtained by bronchoalveolar lavage of normal non-smokers (n=11) and phenotypic normal smokers (n=13, 36 +/- 6 pack per year) were screened for mRNA expression of all known apoptotic cell removal receptors using Affymetrix HG-U133 Plus 2.0 chips with TaqMan RT-PCR confirmation. Of the 14 known apoptotic receptors expressed, only MER Tyrosine Kinase (MERTK), a transmembrane tyrosine kinase receptor, was significantly up-regulated in smokers. MERTK expression was then assessed in AM of smokers vs nonsmokers by TaqMan RT-PCR, immunohistochemistry, Western and flow analysis. Smoker AM had up-regulation of MERTK mRNA levels (smoker vs non-smoker, 3.6-fold by microarray, p<0.003; 9.5-fold by TaqMan RT-PCR, p<0.02). Immunohistochemistry demonstrated a qualitative increase in MERTK protein expression on AM of smokers. Increased protein expression of MERTK on AM of smokers was confirmed by Western and flow analyses (p< 0.007 and p< 0.0002, respectively). MERTK, a cell surface receptor that recognizes apoptotic cells, is expressed on human AM, and its expression is up-regulated in AM of cigarette smokers. This may reflect an increased demand for removal of apoptotic cells in smokers, an observation with implications for the development of chronic obstructive pulmonary disease (COPD), a disorder associated with dysregulated apoptosis of lung parenchymal cells. Experiment Overall Design: Alveolar macrophages were obtained from bronchoalveolar lavage.
Project description:Many apoptotic thymocytes are generated during the course of T cell selection in the thymus, yet the machinery through which these dead cells are recognized and phagocytically cleared is incompletely understood. We find that the TAM receptor tyrosine kinases Axl and Mer, which are co-expressed by a specialized set of phagocytic thymic macrophages, are essential components of this machinery. Axl-/-Mertk-/- double mutant mice exhibited a marked accumulation of apoptotic cells during the time that autoreactive and nonreactive thymocytes die. Unexpectedly, the double mutants also displayed a profound deficit in the total number of phagocytic macrophages in the thymus, and concomitantly exhibited diminished expression of key non-TAM engulfment systems in the macrophages that remain. These previously unrecognized deficits were not confined to the thymus, and were also evident in the bone marrow and spleen. They had pleiotropic metabolic consequences for the double mutants, which included severe dysregulation of hemoglobin turnover, iron metabolism, and erythropoiesis.
Project description:Tumor cells attract and dynamically interact with monocytes/macrophages to subvert their differentiation into tumor associated macrophages (TAMs), which mainly promote immunosuppression and neoplastic progression, but the pathways and microenvironmental cues governing their protumoral deviation are not completely understood. Thus, identifying molecular pathways responsible for TAM differentiation may provide new therapeutic targets to improve the efficacy of immunotherapy of cancer.
Project description:Depletion of immunosuppressive tumor-associated macrophages (TAM) or reprogramming towards a pro-inflammatory activation state represent different strategies to therapeutically target this frequent myeloid population. Here we report that inhibition of colony-stimulating factor-1 receptor (CSF-1R) signaling sensitizes TAM to profound reprogramming in the presence of a CD40 agonist prior to their depletion. Despite the short-lived nature of macrophage hyperactivation, combined CSF-1R/CD40 stimulation of macrophages is sufficient to trigger a productive and durable T cell response in various mouse cancer models. The central role of macrophages in regulating T cell-dependent tumor rejections was substantiated by depletion experiments and transcriptomic analysis of ex vivo sorted TAM. Since CD40 expression on human TAM varies between different tumor types, co-expression of human CSF-1R and CD40 in colorectal adenocarcinoma and mesothelioma can serve as criteria to select these tumor types for clinical development
Project description:A comprehensive understanding of the changes in gene expression in cell types involved in idiopathic pulmonary fibrosis (IPF) will shed light on the mechanisms underlying the loss of alveolar epithelial cells, and development of honeycomb cysts and fibroblastic foci. We sought to understand changes in IPF lung cell transcriptomes and gain insight into innate immune aspects of pathogenesis. We investigated IPF pathogenesis using single cell RNA-sequencing of fresh lung explants, comparing human IPF fibrotic lower lobes reflecting late disease, upper lobes reflecting early disease and normal lungs. IPF lower lobes showed increased fibroblasts, and basal, ciliated, goblet and club cells, but decreased alveolar epithelial cells, and marked alterations in inflammatory cells. We found three discrete macrophage subpopulations in normal and fibrotic lungs, one expressing monocyte markers, one highly expressing FABP4 and INHBA (FABP4hi), and one highly expressing SPP1 and MERTK (SPP1hi). SPP1hi macrophages in fibrotic lower lobes showed highly upregulated SPP1 and MERTK expression. Low-level local proliferation of SPP1hi macrophages in normal lungs was strikingly increased in IPF lungs. Co-localization and causal modeling supported the role for these highly proliferative SPP1hi macrophages in activation of IPF myofibroblasts in lung fibrosis. These data suggest SPP1hi macrophages contribute importantly to lung fibrosis in IPF, and that therapeutic strategies targeting MERTK and macrophage proliferation may show promise for treatment of this disease.
Project description:Regeneration of alveolar bone is an essential step in restoring healthy function following tooth extraction. Growth of new bone in the healing extraction socket can be variable and often unpredictable when systemic comorbidities are present, leading to the need for additional therapeutic targets to accelerate the regenerative process. This study examined the effect of signaling through the TAM (Tyro3, Axl, Mertk) family of receptors on alveolar bone regeneration. We performed RNA sequencing on human alveolar bone stem cells treated with a pan-TAM inhibitor in vitro. We also performed RNA sequencing on tissue isolated from the extraction socket of WT and Mertk-\- mice.