[Show abstract][Hide abstract] ABSTRACT: Mast cell-released chemical mediators such as histamine, leukotriene (LT) C(4) and prostaglandin (PG) D(2) lead to the onset of allergic disorders. ATP provided from glycolysis is essential for histamine release and LTC(4) secretion from mast cells upon Fc epsilon RI cross-linking, indicating that glucose is a primary environmental factor for mast cell activation. In this study, we investigated whether increases in concentrations of glucose in culture media affect the activation of bone marrow-derived mouse mast cells (BMMCs) upon Fc epsilon RI cross-linking.
BMMCs were cultured in RPMI-1640 supplemented with varying concentrations (5.5, 11, 16.5, 22, 27.5 and 33 mM) of D-glucose for 3 h, or 1, 3 or 7 days. D-Mannitol was added to the medium containing 5.5 mMD-glucose for osmotic control. After culturing, these cells were sensitized with anti-TNP IgE and then stimulated with TNP-BSA.
We found that long-term culture (7 days) of BMMCs with 33 mMD-glucose increases the Fc epsilon RI-dependent release of beta-hexosaminidase and LTC(4) without affecting surface expression levels of Fc epsilon RI, intracellular ATP levels or calcium signaling. Biochemical analyses demonstrated that Fc epsilon RI-dependent phosphorylation of cytosolic phospholipase A(2) (cPLA(2)) at the Ser505 residue was significantly increased by culturing with 33 mM glucose.
Taken together, our data suggest that glucose can augment Fc epsilon RI-mediated mast cell activation, particularly the degranulation response and LTC(4) secretion after prolonged culture of mast cells with high-glucose medium. Moreover, it is suggested that increased phosphorylation of cPLA(2) at the Ser505 residue contributes to the enhancement of LTC(4) secretion.
No preview · Article · Jun 2010 · International Archives of Allergy and Immunology
[Show abstract][Hide abstract] ABSTRACT: Inflammatory mediators released from mast cells (MCs) through engagement of the high-affinity receptor for IgE (FcepsilonRI) have pivotal roles in chemical allergen-induced contact hypersensitivity (CHS) reactions, which suggests that the blockade of MC activation through FcepsilonRI stimulation may attenuate allergic contact dermatitis (CD). To address this possibility, we employed the following two approaches: (i) modulation of FcepsilonRI-mediated MC activation by introducing mutations in tyrosine residues of the FcepsilonRI beta-chain immunoreceptor tyrosine-based activation motif (ITAM) and (ii) blockade of FcepsilonRI-mediated MC activation employing a recombinant soluble ecto-domain of the human FcepsilonRIalpha-chain (rsFcepsilonRIalpha). In this study, we show that optimal MC activation through the FcepsilonRI beta-chain ITAM has essential roles in the onset of CHS to oxazolone (Oxa), a well-characterized chemical allergen. In addition, we demonstrate that administration of the rsFcepsilonRIalpha after sensitization successfully prevents murine CHS to Oxa. In a chronic CD model elicited by multiple challenges with low-dose Oxa, application of the rsFcepsilonRIalpha during the course of the challenges showed suppressive effects on CHS to Oxa. Taken together, our data indicate that inhibition of FcepsilonRI-dependent MC activation can suppress allergic CD.
No preview · Article · Oct 2009 · Journal of Investigative Dermatology