Background Rapid desensitization transiently prevents severe allergic reactions, allowing administration of life-saving therapies in previously sensitized patients. However, the mechanisms underlying ...successful rapid desensitization are not fully understood. Objectives We sought to investigate whether the mast cell (MC) is an important target of rapid desensitization in mice sensitized to exhibit IgE-dependent passive systemic anaphylaxis in vivo and to investigate the antigen specificity and underlying mechanisms of rapid desensitization in our mouse model. Methods C57BL/6 mice ( in vivo ) or primary isolated C57BL/6 mouse peritoneal mast cells (PMCs; in vitro ) were passively sensitized with antigen-specific anti–2,4-dinitrophenyl IgE, anti-ovalbumin IgE, or both. MCs were exposed over a short period of time to increasing amounts of antigen (2,4-dinitrophenyl–human serum albumin or ovalbumin) in the presence of extracellular calcium in vitro or by means of intravenous administration to sensitized mice in vivo before challenging the mice with or exposing the PMCs to optimal amounts of specific or irrelevant antigen. Results Rapidly exposing mice or PMCs to progressively increasing amounts of specific antigen inhibited the development of antigen-induced hypothermia in sensitized mice in vivo and inhibited antigen-induced PMC degranulation and prostaglandin D2 synthesis in vitro . Such MC hyporesponsiveness was induced antigen-specifically and was associated with a significant reduction in antigen-specific IgE levels on MC surfaces. Conclusions Rapidly exposing MCs to progressively increasing amounts of antigen can both enhance the internalization of antigen-specific IgE on the MC surface and also desensitize these cells in an antigen-specific manner in vivo and in vitro.
Ingestion of innocuous antigens, including food proteins, normally results in local and systemic immune nonresponsiveness in a process termed oral tolerance. Oral tolerance to food proteins is likely ...to be intimately linked to mechanisms that are responsible for gastrointestinal tolerance to large numbers of commensal microbes. Here we review our current understanding of the immune mechanisms responsible for oral tolerance and how perturbations in these mechanisms might promote the loss of oral tolerance and development of food allergies. Roles for the commensal microbiome in promoting oral tolerance and the association of intestinal dysbiosis with food allergy are discussed. Growing evidence supports cutaneous sensitization to food antigens as one possible mechanism leading to the failure to develop or loss of oral tolerance. A goal of immunotherapy for food allergies is to induce sustained desensitization or even true long-term oral tolerance to food allergens through mechanisms that might in part overlap with those associated with the development of natural oral tolerance.
...the authors provided evidence that mast cells can take up soluble or particulate antigens in an IFN-γ- and IgG opsonization-independent manner and that mast cells could “co-opt” their ...protease-containing secretory granules for antigen processing and presentation. The idea that mast cells can function as APCs in addition to being versatile effector cells of innate and adaptive immune responses is not new and initially generated some skepticism.2 It is well established that a “professional APC” must be able to deliver 3 signals needed to activate CD4+ T cells: (1) presentation of peptide-MHC class II complexes to specific T-cell receptors (after internalization of soluble or particulate antigens and processing and loading of antigen-derived peptides onto MHC class II to create complexes, which are then translocated to the APC surface), (2) expression of certain costimulatory molecules, and (3) production of “instructive” cytokines.2 Professional APCs also must be able to respond to local signals through pattern recognition receptors, migrate to the draining lymph nodes, and activate both naive and memory CD4+ T cells. ...it will now be important to determine under which circumstances, if any, mast cells provide nonredundant APC functions that are critical for shaping particular adaptive immune responses in vivo and whether such APC functions are provided by mast cells in draining lymph nodes, tertiary lymphoid structures, and/or locally in tissues where mast cells normally reside. 1 S. Lotfi-Emran, B.R. Ward, Q.T. Le, A.L. Pozez, M.H. Manjili, J. Woodfolk, T cells, J Allergy Clin Immunol, Vol. 141, 2018, 311-321.e10 2 T. Kambayashi, T.M. Laufer, Nat Rev Immunol, Vol. 14, 2014, 719-730 3 N. Koch, G.H. Wong, J.W. Schrader, Ia antigens and associated invariant chain are induced simultaneously in lines of T-dependent mast cells by recombinant interferon-gamma, J Immunol, Vol. 132, 1984, 1361-1369 4 S. Nakae, H. Suto, M. Iikura, M. Kakurai, J.D. Sedgwick, M. Tsai, Mast cells enhance T cell activation: importance of mast cell co-stimulatory molecules and secreted TNF, J Immunol, Vol. 176, 2006, 2238-2248 5 T. Kambayashi, E.J. Allenspach, J.T. Chang, T. Zou, J.E. Shoag, S.R. Reiner, Inducible MHC class II expression by mast cells supports effector and regulatory T cell activation, J Immunol, Vol. 182, 2009, 4686-4695 6 N. Gaudenzio, N. Espagnolle, L.T. Mars, R. Liblau, S. Valitutti, E. Espinosa, Blood, Vol. 114, 2009, 4979-4988 7 S.J. Galli, S. Nakae, M. Tsai, Mast cells in the development of adaptive immune responses, Nat Immunol, Vol. 6, 2005, 135-142 8 N. Nakano, C. Nishiyama, S. Kanada, Y. Niwa, N. Shimokawa, H. Ushio, Blood, Vol. 109, 2007, 4846-4855 9 N. Gaudenzio, C. Laurent, S. Valitutti, E. Espinosa, J Allergy Clin Immunol, Vol. 131, 2013, 1400-1407 10 J.S. Shin, C.P. Shelburne, C. Jin, E.A. LeFurgey, S.N. Abraham, J Immunol, Vol. 177, 2006, 5791-5800
Background The mechanisms contributing to clinical immune tolerance remain incompletely understood. This study provides evidence for specific immune mechanisms that are associated with a model of ...operationally defined clinical tolerance. Objective Our overall objective was to study laboratory changes associated with clinical immune tolerance in antigen-induced T cells, basophils, and antibodies in subjects undergoing oral immunotherapy (OIT) for peanut allergy. Methods In a phase 1 single-site study, we studied participants (n = 23) undergoing peanut OIT and compared them with age-matched allergic control subjects (n = 20) undergoing standard of care (abstaining from peanut) for 24 months. Participants were operationally defined as clinically immune tolerant (IT) if they had no detectable allergic reactions to a peanut oral food challenge after 3 months of therapy withdrawal (IT, n = 7), whereas those who had an allergic reaction were categorized as nontolerant (NT; n = 13). Results Antibody and basophil activation measurements did not statistically differentiate between NT versus IT participants. However, T-cell function and demethylation of forkhead box protein 3 (FOXP3) CpG sites in antigen-induced regulatory T cells were significantly different between IT versus NT participants. When IT participants were withdrawn from peanut therapy for an additional 3 months (total of 6 months), only 3 participants remained classified as IT participants, and 4 participants regained sensitivity along with increased methylation of FOXP3 CpG sites in antigen-induced regulatory T cells. Conclusion In summary, modifications at the DNA level of antigen-induced T-cell subsets might be predictive of a state of operationally defined clinical immune tolerance during peanut OIT.
Background Basophil activation tests (BATs) have promise for research and for clinical monitoring of patients with allergies. However, BAT protocols vary in blood anticoagulant used and temperature ...and time of storage before testing, complicating comparisons of results from various studies. Objective We attempted to establish a BAT protocol that would permit analysis of blood within 24 hours of obtaining the sample. Methods Blood from 46 healthy donors and 120 patients with peanut allergy was collected into EDTA or heparin tubes, and samples were stored at 4°C or room temperature for 4 or 24 hours before performing BATs. Results Stimulation with anti-IgE or IL-3 resulted in strong upregulation of basophil CD203c in samples collected in EDTA or heparin, stored at 4°C, and analyzed 24 hours after sample collection. However, a CD63hi population of basophils was not observed in any conditions in EDTA-treated samples unless exogenous calcium/magnesium was added at the time of anti-IgE stimulation. By contrast, blood samples collected in heparin tubes were adequate for quantification of upregulation of basophil CD203c and identification of a population of CD63hi basophils, irrespective of whether the specimens were analyzed by means of conventional flow cytometry or cytometry by time-of-flight mass spectrometry, and such tests could be performed after blood was stored for 24 hours at 4°C. Conclusion BATs to measure upregulation of basophil CD203c and induction of a CD63hi basophil population can be conducted with blood obtained in heparin tubes and stored at 4°C for 24 hours.
Background Studies with c- kit mutant mast cell (MC)–deficient mice and antibody-mediated depletion of basophils suggest that both MCs and basophils can contribute to peanut-induced anaphylaxis ...(PIA). However, interpretation of data obtained by using such approaches is complicated because c- kit mutant mice have several phenotypic abnormalities in addition to MC deficiency and because basophil-depleting antibodies can also react with MCs. Objective We analyzed (1) the changes in the features of PIA in mice after the selective and inducible ablation of MCs or basophils and (2) the possible importance of effector cells other than MCs and basophils in the PIA response. Methods Wild-type and various mutant mice were orally sensitized with peanut extract and cholera toxin weekly for 4 weeks and challenged intraperitoneally with peanut extract 2 weeks later. Results Peanut-challenged, MC-deficient Kit W-sh/W-sh mice had reduced immediate hypothermia, as well as a late-phase decrease in body temperature that was abrogated by antibody-mediated depletion of neutrophils. Diphtheria toxin–mediated selective depletion of MCs or basophils in Mcpt5-Cre ; iDTR and Mcpt8 DTR mice, respectively, and treatment of wild-type mice with the basophil-depleting antibody Ba103 significantly reduced peanut-induced hypothermia. Non–c- kit mutant MC- and basophil-deficient Cpa3-Cre;Mcl-1 fl/fl mice had reduced but still significant responses to peanut. Conclusion Inducible and selective ablation of MCs or basophils in non–c- kit mutant mice can significantly reduce PIA, but partial responses to peanut can still be observed in the virtual absence of both cell types. The neutrophilia in Kit W-sh/W-sh mice might influence the responses of these mice in this PIA model.
Background Mast cells have gained notoriety based on their detrimental contributions to IgE-mediated allergic disorders. Although mast cells express the vitamin D receptor (VDR), it is not clear to ...what extent 1α,25-dihydroxyvitamin D3 (1α,25OH2 D3 ) or its predominant inactive precursor metabolite in the circulation, 25-hydroxyvitamin D3 (25OHD3 ), can influence IgE-mediated mast cell activation and passive cutaneous anaphylaxis (PCA) in vivo. Objective We sought to assess whether the vitamin D3 metabolites 25OHD3 and 1α,25(OH)2 D3 can repress IgE-dependent mast cell activation through mast cell–25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and mast cell–VDR activity. Methods We measured the extent of vitamin D3 suppression of IgE-mediated mast cell degranulation and mediator production in vitro , as well as the vitamin D3 –induced curtailment of PCA responses in WBB6F1 - KitW/W-v or C57BL/6J- KitW-sh/W-sh mice engrafted with mast cells that did or did not express VDR or CYP27B1. Results Here we show that mouse and human mast cells can convert 25OHD3 to 1α,25(OH)2 D3 through CYP27B1 activity and that both of these vitamin D3 metabolites suppressed IgE-induced mast cell–derived proinflammatory and vasodilatory mediator production in a VDR-dependent manner in vitro . Furthermore, epicutaneously applied vitamin D3 metabolites significantly reduced the magnitude of skin swelling associated with IgE-mediated PCA reactions in vivo ; a response that required functional mast cell–VDRs and mast cell–CYP27B1. Conclusion Taken together, our findings provide a mechanistic explanation for the anti-inflammatory effects of vitamin D3 on mast cell function by demonstrating that mast cells can actively metabolize 25OHD3 to dampen IgE-mediated mast cell activation in vitro and in vivo.
We report herein a simple new fluorescent-avidin-based method to detect activated basophils in the whole blood of normal or allergic subjects, and compare this method to a basophil activation test ...based on detection of CD63.
Background Mast cells express receptors for complement anaphylatoxins C3a and C5a (ie, C3a receptor C3aR and C5a receptor C5aR), and C3a and C5a are generated during various IgE-dependent immediate ...hypersensitivity reactions in vivo . However, it is not clear to what extent mast cell expression of C3aR or C5aR influences C3a- or C5a-induced cutaneous responses or IgE-dependent mast cell activation and passive cutaneous anaphylaxis (PCA) in vivo. Objective We sought to assess whether mouse skin mast cell expression of C3aR or C5aR influences (1) the cells' responsiveness to intradermal injections of C3a or C5a or (2) the extent of IgE-dependent mast cell degranulation and PCA in vivo. Methods We measured the magnitude of cutaneous responses to intradermal injections of C3a or C5a and the extent of IgE-dependent mast cell degranulation and PCA responses in mice containing mast cells that did or did not express C3aR or C5aR. Results The majority of the skin swelling induced by means of intradermal injection of C3a or C5a required that mast cells at the site expressed C3aR or C5aR, respectively, and the extent of IgE-dependent degranulation of skin mast cells and IgE-dependent PCA was significantly reduced when mast cells lacked either C3aR or C5aR. IgE-dependent PCA responses associated with local increases in C3a levels occurred in antibody-deficient mice but not in mice deficient in FcεRIγ. Conclusion Expression of C3aR and C5aR by skin mast cells contributes importantly to the ability of C3a and C5a to induce skin swelling and can enhance mast cell degranulation and inflammation during IgE-dependent PCA in vivo.
IgG subclasses determine pathways of anaphylaxis in mice Beutier, Héloïse, PharmD; Gillis, Caitlin M., BSci; Iannascoli, Bruno, BTS ...
Journal of allergy and clinical immunology,
01/2017, Letnik:
139, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Background Animal models have demonstrated that allergen-specific IgG confers sensitivity to systemic anaphylaxis that relies on IgG Fc receptors (FcγRs). Mouse IgG2a and IgG2b bind activating FcγRI, ...FcγRIII, and FcγRIV and inhibitory FcγRIIB; mouse IgG1 binds only FcγRIII and FcγRIIB. Although these interactions are of strikingly different affinities, these 3 IgG subclasses have been shown to enable induction of systemic anaphylaxis. Objective We sought to determine which pathways control the induction of IgG1 -, IgG2a -, and IgG2b -dependent passive systemic anaphylaxis. Methods Mice were sensitized with IgG1 , IgG2a , or IgG2b anti-trinitrophenyl mAbs and challenged with trinitrophenyl-BSA intravenously to induce systemic anaphylaxis that was monitored by using rectal temperature. Anaphylaxis was evaluated in mice deficient for FcγRs injected with mediator antagonists or in which basophils, monocytes/macrophages, or neutrophils had been depleted. FcγR expression was evaluated on these cells before and after anaphylaxis. Results Activating FcγRIII is the receptor primarily responsible for all 3 models of anaphylaxis, and subsequent downregulation of this receptor was observed. These models differentially relied on histamine release and the contribution of mast cells, basophils, macrophages, and neutrophils. Strikingly, basophil contribution and histamine predominance in mice with IgG1 - and IgG2b -induced anaphylaxis correlated with the ability of inhibitory FcγRIIB to negatively regulate these models of anaphylaxis. Conclusion We propose that the differential expression of inhibitory FcγRIIB on myeloid cells and its differential binding of IgG subclasses controls the contributions of mast cells, basophils, neutrophils, and macrophages to IgG subclass–dependent anaphylaxis. Collectively, our results unravel novel complexities in the involvement and regulation of cell populations in IgG-dependent reactions in vivo.
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