Project description:Comparing Trem2-KO;PS2APP and Trem2-WT;PS2APP CD11b+ cells reveals the role of Trem2 in microglial gene expression in amyloid-laden brains. The "SAMPLE_ID" sample characteristic is a sample identifier internal to Genentech. The ID of this project in Genentech's ExpressionPlot database is PRJ0014430
Project description:The prevailing view is that myeloid cells in the tumor microenvironment (TME) are immunosuppressive and promote glioblastoma (GBM) progression. However, myeloid cells have the functional plasticity to restrict or support tumor cell growth. TREM2 plays important roles in brain microglial function in neurodegenerative diseases, but the role of TREM2 in the GBM TME has not been examined. We found TREM2 is highly expressed in myeloid subsets, including macrophages and microglia in human and mouse GBM tumors and that high TREM2 expression correlates with poor prognosis in GBM patients. TREM2 loss of function in human macrophages and mouse myeloid cells increased tumoricidal capacity. TREM2 in myeloid cells restricts IFNγ-induced immunoactivation and proinflammatory polarization. In orthotopic mouse GBM models, Trem2-/- mice and mice with acute brain Trem2 reduction demonstrate survival benefit. Trem2 inhibition reprograms myeloid phenotypes and increases PD-1+CD8+ T cells in the TME. Trem2 deficiency enhances the effectiveness of anti-PD-1 treatment and may represent a therapeutic strategy for GBM patients.
Project description:The prevailing view is that myeloid cells in the tumor microenvironment (TME) are immunosuppressive and promote glioblastoma (GBM) progression. However, myeloid cells have the functional plasticity to restrict or support tumor cell growth. TREM2 plays important roles in brain microglial function in neurodegenerative diseases, but the role of TREM2 in the GBM TME has not been examined. We found TREM2 is highly expressed in myeloid subsets, including macrophages and microglia in human and mouse GBM tumors and that high TREM2 expression correlates with poor prognosis in GBM patients. TREM2 loss of function in human macrophages and mouse myeloid cells increased tumoricidal capacity. TREM2 in myeloid cells restricts IFNγ-induced immunoactivation and proinflammatory polarization. In orthotopic mouse GBM models, Trem2-/- mice and mice with acute brain Trem2 reduction demonstrate survival benefit. Trem2 inhibition reprograms myeloid phenotypes and increases PD-1+CD8+ T cells in the TME. Trem2 deficiency enhances the effectiveness of anti-PD-1 treatment and may represent a therapeutic strategy for GBM patients.
Project description:Triggering receptor expressed on myeloid cells 2 (TREM2) is an orphan immune receptor expressed on cells of myeloid lineage such as macrophages and microglia. The rare–variant R47H TREM2 is associated with an increased risk for Alzheimer’s disease (AD), supporting the hypothesis that TREM2 loss of function may exacerbate disease progression. However, a complete knockout of the TREM2 gene in different genetic models of neurodegenerative diseases has been reported to result in both protective and deleterious effects on disease-related endpoints and myeloid cell function. Here, we describe a TREM2R47H transgenic mouse model and report that even in the absence of additional genetic perturbations, this variant clearly confers a loss of function on myeloid cells. The TREM2R47H variant–containing myeloid cells exhibited subtle defects in survival and migration and displayed an unexpected dysregulation of cytokine responses in a lipopolysaccharide challenge environment. These subtle phenotypic defects with a gradation in severity across genotypes were confirmed in whole-genome RNA-Seq analyses of WT, TREM2−/− and TREM2R47H myeloid cells under challenge conditions. Of note, TREM2-activating antibodies that boost proximal signaling abrogated survival defects conferred by the variant and also modulated migration and cytokine responses in an antibody-, ligand-, and challenge-dependent manner. In some instances, these antibodies also boosted wildtype myeloid cell function. Our studies provide a first glimpse into the boost in myeloid cell function that can be achieved by pharmacological modulation of TREM2 activity that can potentially be ameliorative in neurodegenerative diseases such as AD.
Project description:Microglia are phagocytic cells that survey the brain and perform neuroprotective functions in response to tissue damage, but their activating receptors are largely unknown. Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial immunoreceptor whose loss-of-function mutations in humans cause presenile dementia, while genetic variants are associated with increased risk of neurodegenerative diseases. In myeloid cells, TREM2 has been involved in the regulation of phagocytosis, cell proliferation and inflammatory responses in vitro. However, it is unknown how TREM2 contributes to microglia function in vivo. Here, we identify a critical role for TREM2 in the activation and function of microglia during cuprizone (CPZ)-induced demyelination. TREM2-deficient (TREM2(-/-)) mice had defective clearance of myelin debris and more axonal pathology, resulting in impaired clinical performances compared to wild-type (WT) mice. TREM2(-/-) microglia proliferated less in areas of demyelination and were less activated, displaying a more resting morphology and decreased expression of the activation markers MHC II and inducible nitric oxide synthase as compared to WT. Mechanistically, gene expression and ultrastructural analysis of microglia suggested a defect in myelin degradation and phagosome processing during CPZ intoxication in TREM2(-/-) microglia. These findings place TREM2 as a key regulator of microglia activation in vivo in response to tissue damage. Two STAGE (6weeks 12 weeks),
Project description:TREM2 signaling in myeloid cells functions as a major pathology-induced immune signaling hub in trauma- and autoimmune-mediated neurodegeneration. Here we compared the influence of TREM2 signaling on single-cell transcriptional profiles of mouse myeloid populations during the pathologies of spinal cord injury (SCI) and multiple sclerosis (MS) models.
Project description:Checkpoint immunotherapy unleashes T cell effector functions that control tumor growth, but can be undermined by myeloid cells that induce immunosuppression. TREM2 is a myeloid surface receptor that binds lipids and transmits intracellular signals through protein-tyrosine phosphorylation known to sustain microglial responses during Alzheimer’s disease. Intriguingly, TREM2 expression has recently been noted in tumor-infiltrating macrophages. We found that Trem2–/– mice are more resistant to growth of sarcoma, colorectal and mammary cancer cells than wild-type mice and are more responsive to anti-PD-1 immunotherapy. Furthermore, treatment with anti-TREM2 mAb curbed tumor growth and led to complete tumor regression when combined with anti-PD-1. scRNA-seq revealed that both constitutive TREM2 deficiency and anti-TREM2 are associated with relatively scant representation of MRC1+ and CX3CR1+ subsets in the macrophage tumor infiltrate, paralleled by expansion of subsets expressing immunostimulatory molecules. These changes were associated with improved T cell responses. TREM2 expression was evident in tumor macrophages in over 200 human cancer cases examined and inversely correlated with prolonged survival for two types of cancer. Thus, TREM2 is a promising target to modify tumor-infiltrating myeloid cells and effectively augment checkpoint immunotherapy.