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  • 1
    Online Resource
    Online Resource
    Abstract 178: Cholesterol Limits Macrophage Activation in Response to Intracerebral Hemorrhage-Relevant Signals
    Ovid Technologies (Wolters Kluwer Health) ; 2020
    In:  Stroke Vol. 51, No. Suppl_1 ( 2020-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 51, No. Suppl_1 ( 2020-02)
    Abstract: Introduction: In response to intracerebral hemorrhage (ICH), monocytes are recruited to the brain parenchyma, where they differentiate into macrophages and contribute to a pathological inflammatory response. However, by day 3 after ICH, brain macrophages have adopted a more reparative phenotype and are important for clearance of apoptotic cells and recovery. The signals that control this inflammatory to reparative differentiation are incompletely understood, but cholesterol has been found to limit macrophage activation in multiple systems. The brain has the highest cholesterol content of any organ and we hypothesized that cholesterol uptake by macrophages limits inflammation and promotes the development of reparative macrophages following ICH. Methods and Results: Murine bone marrow-derived macrophages were stimulated with a cocktail of thrombin, S100A8, and IL-1b in order to mimic the Danger-Associated Molecular Patterns present in the brain after ICH (ICH-DAMP), LPS, or vehicle for 14-18 hours. Cytokine production was quantified by cytometric bead array and activation markers by flow cytometry. ICH-DAMP was found to upregulate CCL2, IL-6 and TNF, recapitulating the inflammatory phenotype seen in the first days after ICH. However, when cells were stimulated in the presence of cholesterol, production of CCL2, IL-6, and TNF were limited. Dectin-1 has inhibitory properties in some sterile injury models. ICH-DAMP was found to limit expression of dectin-1, and cholesterol reversed this inhibition. Exposure to exogenous cholesterol also upregulated the cholesterol transporter ABCA1, allowing cells to efflux excess cholesterol. The drug Valspodar was therefore used to block cholesterol efflux and was found to further limit ICH-DAMP-mediated upregulation of CCL2. Conclusion: These results suggest that the cholesterol in the brain may limit macrophage activation in response to the stimuli present during intracerebral hemorrhage.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.51.suppl_1.178
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
    detail.hit.zdb_id: 1467823-8
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  • 2
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    Abstract TP239: Cholesterol And LXR Signaling In The Macrophage Response To Intracerebral Hemorrhage-relevant Stimulation
    Ovid Technologies (Wolters Kluwer Health) ; 2022
    In:  Stroke Vol. 53, No. Suppl_1 ( 2022-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 53, No. Suppl_1 ( 2022-02)
    Abstract: Introduction: In the acute phase of intracerebral hemorrhage (ICH), blood-derived macrophages contribute to an inflammatory response that increases neuronal death and worsens patient outcome. A better understanding of the endogenous signals that control this response would aid in development of therapeutics to suppress it. Uptake of free cholesterol limits the macrophage response to microbial ligands, in part through activation of the transcription factor LXR. During ICH, blood-derived macrophages in the hematoma are not exposed to microbes but are exposed to the endogenous inflammatory molecule S100A9 as well as cholesterol in the form of myelin and cell debris. Methods and Results: Murine bone marrow-derived macrophages were treated with cholesterol before stimulation with S100A9 or LPS, which are both TLR4 ligands. The inflammatory response was measured by production of the cytokines/chemokines TNF, IL-6, CCL2, and IL-10 by multiplex ELISA and/or qPCR at 3 and 6 hours after stimulation. Activation of LXR was measured by expression of the LXR target genes Abca1 and Abcg1 by qPCR. Cholesterol limited inflammatory cytokine production in response to LPS but not to S100A9. Treatment with the LXR agonist T0901317 activated Abca1 and Abcg1 more strongly than cholesterol but was not as effective at suppressing cytokine production. Treatment with the LXR antagonist GSK2033 suppressed cholesterol-mediated expression of Abca1 and Abcg1 but did not block all suppressive effects of cholesterol on cytokine production. Conclusions: Cholesterol limits the macrophage response to LPS. This is partially through activation of LXR, but LXR-independent mechanisms are involved as well. Cholesterol does not limit the initial inflammatory response to the ICH-relevant molecule S100A9, which may help explain the robust acute inflammatory response that develops during acute ICH in the presence of abundant cholesterol.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.53.suppl_1.TP239
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 1467823-8
    Location Call Number Limitation Availability
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  • 3
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    Online Resource
    Cholesterol, LXR activation, and myelin uptake in the macrophage response to diverse signals
    The American Association of Immunologists ; 2022
    In:  The Journal of Immunology Vol. 208, No. 1_Supplement ( 2022-05-01), p. 111.23-111.23
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 208, No. 1_Supplement ( 2022-05-01), p. 111.23-111.23
    Abstract: Monocyte-derived macrophages contribute to neurotoxic inflammation during hemorrhagic stroke. Cholesterol is an immunosuppressive molecule present at high levels in the brain, primarily as a component of myelin. Uptake of myelin and activation of the transcription factor LXR downstream of myelin and cholesterol uptake limits the macrophage response to LPS. However, the roles of these molecules in macrophage responses to the endogenous signals present during sterile inflammation are poorly understood. The present study seeks to determine what role myelin, cholesterol, and LXR activation play in modifying macrophage responses to diverse signals. Methods and Results Murine bone marrow-derived macrophages were treated with myelin, cholesterol, or the LXR agonist T0901317 18h before stimulation with S100A9, IFN-g, TNF-a, IL-4, IL-10, TGF-b, p(I:C), Pam3CSK4, or LPS. Production of TNF-a, IL-6, CCL2, and IL-10 were measured by multiplex ELISA. Transcriptome-wide effects were measured by RNA sequencing. Cholesterol limited inflammatory cytokine production in response to LPS but not to other stimuli. The LXR agonist T0901317 did not suppress cytokine production. Principal component analysis revealed that cholesterol had strong effects on the transcriptomic responses to LPS but not to the other stimulations. Myelin affected the transcriptomic response to all inflammatory stimulations. Conclusions Cholesterol limits the macrophage response to LPS, partially through activation of LXR, but does not broadly limit macrophage activation. Uptake of myelin has broader effects than cholesterol, suggesting that non-cholesterol components of myelin modulate the macrophage response. Supported by grants from NIH (R01 NS097728,  T32 HL007950) and AHA (Postdoctoral Fellowship 830877)
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.208.Supp.111.23
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2022
    detail.hit.zdb_id: 1475085-5
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