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  • Askenase, Michael H  (2)
  • 1
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 48, No. suppl_1 ( 2017-02)
    Abstract: Intracerebral hemorrhage (ICH) causes rapid recruitment of circulating leukocytes to the injury; however, the roles of these cells in disease progression and repair in the brain are poorly understood. Findings from animal models have failed to translate into effective therapies for ICH, emphasizing the importance of studying the ICH immune response in the patient population. To gain insight into the inflammatory response in patient hematomas, we are utilizing mass cytometry, flow cytometry, and RNA-seq to characterize hematoma-infiltrating leukocytes isolated from ICH patients over a 5 day period, in conjunction with the ongoing MISTIE III trial for surgical evacuation of ICH. We have found that the hematoma immune infiltrate is predominantly composed of neutrophils and macrophages recruited from the circulation, rather than CNS-resident microglia. We have observed that hematoma macrophages have acquired a distinct phenotype differing from phagocyte populations in the peripheral blood, suggesting that their gene expression is controlled by local signals in the hematoma. Preliminary transcriptional analysis of hematoma macrophages 24-50 hours post-ICH has revealed an inflammatory profile characterized by increased expression of antigen presentation, TLR signaling, glycolytic metabolism, and prostaglandin production pathways (Figure 1). Intriguingly, by 100 hours post-ICH, macrophages downregulated these pathways and engaged a wound healing program characterized by TGF-beta signaling, fatty acid metabolism, and collagen deposition (Figure 1). These findings, in agreement with our previous results in animal models of ICH, suggest that recruited macrophages may contribute not only to initial inflammatory damage, but also to clearance of the hematoma and resolution of inflammation, making them potentially ideal targets for therapeutic intervention.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2017
    detail.hit.zdb_id: 1467823-8
    Location Call Number Limitation Availability
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  • 2
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 48, No. suppl_1 ( 2017-02)
    Abstract: Introduction: After intracerebral hemorrhage (ICH), erythrocytes contribute to secondary injury by releasing toxic hemoproteins. Our lab has previously shown that blood derived macrophages play an important role in ICH clearance but mechanisms of phagocytosis by human macrophages are unknown. This study aims to quantify eryptotic (phosphatidylserine (PtdSer)-expressing) red blood cells (RBCs) in an in vivo model of ICH, and to investigate the mechanisms that play a role in autologous eryptotic phagocytosis by human monocyte derived macrophages (huMDMs). Methods: ICH was induced in mice by autologous blood injection. The mice were sacrificed at 1 day after ICH. The brains were separated into hemispheres and digested into a single cell suspension for analysis by flow cytometry. Cells were stained with antibodies to cell surface markers and annexin V to quantify externalized PtdSer expression. Human monocytes were cultured with M-CSF for 7 days to generate huMDMs. Autologous RBCs were heat shocked (HS) to induce eryptosis. The huMDMs were cocultured with HS RBCs, HS RBCs treated with annexin V, or control RBCs. After 1 hour of coculture, the huMDMs were washed, stained and erythrophagocytosis quantified by microscopy. Results: The proportion of cells that externalized PtdSer increased by almost 20 fold at day 1 after ICH. Control brains mixed with fresh RBCs and subjected to tissue prep did not show PtdSer expression, ensuring that the PtdSer expression detected was induced in vivo (Fig A). HS RBCs increased PtdSer expression and were efficiently phagocytosed by huMDMs. Treatment of HS RBCs with annexin V to antagonize PtdSer-receptor interactions decreased RBC phagocytosis to levels comparable to control RBCs (Figs B and C). Conclusions: In vivo after ICH, erythrocytes externalize PtdSer, a cue to be engulfed by macrophages. Human macrophages phagocytose RBCs in a PtdSer-dependent mechanism. These findings highlight potential targets to enhance ICH clearance.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2017
    detail.hit.zdb_id: 1467823-8
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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