Oxysterol represses high-affinity IgE receptor-stimulated mast cell activation in Liver X receptor-dependent and -independent manners

Division of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University Graduate School of Medical Science, Tokyo, Japan.
FEBS letters (Impact Factor: 3.17). 02/2010; 584(6):1143-8. DOI: 10.1016/j.febslet.2010.02.006
Source: PubMed

ABSTRACT Oxysterols activating liver X receptors (LXRs) repress expression of pro-inflammatory genes and have anti-inflammatory effects. Here, we show for the first time that bone marrow-derived murine mast cells (BMMCs) predominantly express LXRbeta. 25-hydroxycholesterol, a representative LXR activating oxysterol, suppressed IL-6 production and degranulation response in BMMCs following engagement of high-affinity IgE receptor (FcepsilonRI). Interestingly, 25-hydroxycholesterol reduced cell-surface FcepsilonRI expression by inhibiting assembly of FcepsilonRIalpha and FcepsilonRIbeta. We demonstrate that LXR activation was involved in the suppression of IL-6 production in BMMCs, but that reduced FcepsilonRI expression and degranulation response was mediated in an LXR-independent manner.

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    • "As the key effector molecule of type I hypersensitivity, IgE is critical for allergic immune reaction and AHR [17]. Previous studies have demonstrated that Liver X receptors attenuate IgE expression in B cells [18] and high-affinity IgE receptor-stimulated mast cell activation [19]. In our study, OVA-specific IgE production was blocked by T0901317 in animal models of asthma. "
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    ABSTRACT: The liver-X-receptors have shown anti-inflammatory ability in several animal models of respiratory disease. Our purpose is to investigate the effect of LXR ligand in allergen-induced airway remodeling in mice. Ovalbumin-sensitized mice were chronically challenged with aerosolized ovalbumin for 8 weeks. Some mice were administered a LXR agonist, T0901317 (12.5, 25, 50 mg/kg bodyweight) before challenge. Then mice were evaluated for airway inflammation, airway hyperresponsiveness and airway remodeling. T0901317 failed to attenuate the inflammatory cells and Th2 cytokines in bronchoalveolar lavage fluid. But the application of T0901317 reduced the thickness of airway smooth muscle and the collagen deposition. Meanwhile, T0901317 treatment evidently abolished the high level of OVA-specific IgE, TGF-β1 and MMP-9 in lung. So LXRs may attenuate the progressing of airway remodeling, providing a potential treatment of asthma.
    PLoS ONE 03/2014; 9(3):e92668. DOI:10.1371/journal.pone.0092668 · 3.23 Impact Factor
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    ABSTRACT: The oxysterol-producing enzyme CH25H plays an important role in regulating lipid metabolism, gene expression, and immune activation. In vitro experiments using a panel of TLR agonists to activate BMDCs and macrophages demonstrated that Ch25h expression is induced rapidly, selectively, and robustly by the TLR ligands poly I:C and LPS. The mechanism of TLR3- and TLR4-induced transcription levels of Ch25h relies on the TRIF-mediated production of type I IFNs and requires signaling through the IFNαR and JAK/STAT1 pathway. Treatment of BMDCs and macrophages with IFN-α or IFN-β induces Ch25h in a STAT1-dependent manner. IFN-γ also up-regulated Ch25h expression by signaling through STAT1, suggesting that multiple pathways regulate the production of this enzyme. In addition, we demonstrated that regulation of Ch25h expression in vivo in lung-derived DCs and macrophages is dependent on signaling through the IFNαR and STAT1. The results suggest that the rapid induction of Ch25h and subsequent oxysterol synthesis may represent a component of the regulatory network that modulates the magnitude of innate immune reactions and possibly the nature and intensity of subsequent adaptive responses.
    Journal of leukocyte biology 12/2010; 88(6):1081-7. DOI:10.1189/jlb.0610318 · 4.29 Impact Factor
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    ABSTRACT: The biological function of the Nr4a subfamily of nuclear receptors is only partially understood. Here we show for the fist time that mast cell (MC) activation processes involve the regulation of Nr4a factors. Exposure of murine bone marrow-derived MCs (BMMCs) to live bacteria causes a robust and selective upregulation of all Nr4a members (Nr4a1-Nr4a3). In response to purified LPS, strong upregulation of Nr4a3, but not of Nr4a1 or Nr4a2 was seen. Nr4a3 expression was also induced after the activation of BMMCs by IgE receptor cross-linking. Moreover, Nr4a expression was induced in activated human MCs. As shown by Western blot analysis, Nr4a phosphorylation was induced by IgE receptor cross-linking and calcium ionophore stimulation of BMMCs and LAD2 cells, respectively. By using various inhibitors of signaling pathways, Nr4a3 induction in BMMCs was shown to be strongly dependent on Gö6976-sensitive kinases and partially dependent on the nuclear factor of activated T-cells (NFAT) pathway, while nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) inhibition failed to inhibit Nr4a3 expression in BMMCs. Together, these data reveal selective induction of Nr4a family members in activated MCs and implicate Nr4a family nuclear receptors in the regulation of MC function.
    Molecular Immunology 05/2011; 48(15-16):1753-61. DOI:10.1016/j.molimm.2011.04.017 · 2.97 Impact Factor
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