Project description:The underlying mechanisms of IgE-mediated anaphylaxis remain poorly understood. Furthermore, it remains to be determined to what extent findings from animal/mouse models reflects the pathophysiological mechanism in human. Therefore, to better characterize the mechanisms leading to potentially lethal events, analysis of global transcriptional changes (RNA-sequencing) in peripheral blood human samples in patients with anaphylaxis presenting at the emergency department and in patients with anaphylaxis during double-blind placebo-controlled food challenges (DBPCFC) to peanut, was performed. Mouse samples with different severity of IgE-mediated food-induced anaphylaxis were also included in RNA-sequencing analyses.
Project description:Emergence of IgE antibodies that bind allergens with high affinity is highly correlated with the severity of anaphylaxis. However, the underlying molecular mechanisms by which high-affinity IgE is generated remain poorly understood. We examined the effects of cytokines in IgE class switch using in-vitro B cell activation system
Project description:Emergence of IgE antibodies that bind allergens with high affinity is highly correlated with the severity of anaphylaxis. However, the underlying molecular mechanisms by which high-affinity IgE is generated remain poorly understood. To examine function of IL-13 derived from T cells in IgE producing B cell development, we transferred IL-13 sufficient or deficient OT-2 TH2 into IgE reporter (Verigem) mice followed by immunization with NP-OVA. At 7 day post immunization, NP specific IgE producing B cells were sorted and served to single cell transcriptome analysis.
Project description:Emergence of IgE antibodies that bind allergens with high affinity is highly correlated with the severity of anaphylaxis. However, the underlying molecular mechanisms by which high-affinity IgE is generated remain poorly understood. We discovered that IL-13-producing T follicular helper (TFH) cells, which we designated as TFH2 cells, are generated from conventional TH2 cells by antigen sensitization. TFH2 cells have a unique cytokine profile (IL-4+IL-5-IL-13+IL-21+) and co-express the TFH and TH2 master transcriptional regulators, BCL-6 and GATA3.
Project description:Experimental IgE-mediated food allergy depends on intestinal anaphylaxis driven by interleukin (IL)-9. However, the primary cellular source of IL-9 and the mechanisms underlying the susceptibility to food-induced intestinal anaphylaxis remain unclear. Herein, we have reported the identification of multifunctional IL-9-producing mucosal mast cells (MMC9s) that can secrete prodigious amounts of IL-9 and IL-13 in response to IL-33, and mast cell protease-1 (MCPt-1) in response to antigen and IgE complex crosslinking, respectively. Repeated intragastric antigen challenge induced MMC9 development that required T cells, IL-4, and STAT6 transcription factor, but not IL-9 signals. Mice ablated of MMC9 induction failed to develop intestinal mastocytosis, which resulted in decreased food allergy symptoms that could be restored by adoptively transferred MMC9s. Finally, atopic patients that developed food allergy displayed increased intestinal expression of Il9 and MC-specific transcripts. Thus, the induction of MMC9s is a pivotal step to acquire the susceptibility to IgE-mediated food allergy. dUTP mRNA-Seq profiles of indicated hematopoietic cell lineages were generated on Illumina HiSeq2500. Hematopoietic cells were isolated from Balb/C mice that developed food allergy and bone marrow-derived mast cells were generated from naïve Balb/C mice
Project description:Experimental IgE-mediated food allergy depends on intestinal anaphylaxis driven by interleukin (IL)-9. However, the primary cellular source of IL-9 and the mechanisms underlying the susceptibility to food-induced intestinal anaphylaxis remain unclear. Herein, we have reported the identification of multifunctional IL-9-producing mucosal mast cells (MMC9s) that can secrete prodigious amounts of IL-9 and IL-13 in response to IL-33, and mast cell protease-1 (MCPt-1) in response to antigen and IgE complex crosslinking, respectively. Repeated intragastric antigen challenge induced MMC9 development that required T cells, IL-4, and STAT6 transcription factor, but not IL-9 signals. Mice ablated of MMC9 induction failed to develop intestinal mastocytosis, which resulted in decreased food allergy symptoms that could be restored by adoptively transferred MMC9s. Finally, atopic patients that developed food allergy displayed increased intestinal expression of Il9 and MC-specific transcripts. Thus, the induction of MMC9s is a pivotal step to acquire the susceptibility to IgE-mediated food allergy.
Project description:We report a rare population of IL-13-producing Tfh cells that were present with high-affinity IgE to allergens. These “Tfh13” cells have an unusual cytokine profile (IL-13hiIL-4hiIL-5hiIL-21lo), co-express BCL6 and GATA3 and were required for production of high- but not low-affinity IgE and accordingly, allergen-induced anaphylaxis.
Project description:Allergy is one of the most prevalent chronic diseases, affecting hundreds of millions of people worldwide. In allergy, environmental allergens induce B cells to undergo class switch recombination and produce Immunoglobulin E (IgE) antibodies. IgE is a key molecule that mediates allergic responses by coating mast cell or basophil surfaces and inducing degranulation upon binding a specific allergen. IgE can also be spontaneously produced in the absence of exogenous allergens, yet the origin, regulation, and functions of such “natural” IgE still remains largely unknown. Here, we discovered that glucocorticoids, which are steroid stress hormones, enhance IgE isotype class switching in B cells both in vivo and ex vivo without antigenic challenge. Such IgE class switching is promoted by B cell-intrinsic glucocorticoid receptor signaling that reinforces CD40 signaling and synergizes with the IL-4/STAT6 pathway. In addition, we found that rare B cells in the mesenteric lymph nodes are responsible for the production of glucocorticoid-inducible IgE. Furthermore, we showed that locally produced glucocorticoids in the gut may induce natural IgE during perturbations of gut homeostasis such as dysbiosis. Notably, mice preemptively treated with glucocorticoids were protected from subsequent IgE-mediated pathogenic anaphylaxis in vivo. Together, our results suggest that glucocorticoids, classically considered to be broadly immunosuppressive, have a selective immunostimulatory role in B cells.
Project description:Background: Despite its increasing incidence, the underlying molecular processes of anaphylaxis remain unclear and there are not known biomarkers for appropriate diagnosis. The mechanism associated to the reactions still needs to be clarified in humans. The rapid onset and potentially fatal outcome in the absence of managed treatment, prevent its study and prompt obvious technical and ethical implications. Methods: Twenty episodes of anaphylaxis were analyzed. Sera was collected at different times: during the acute phase (T1), the recovery phase (T2) and around 2-3 months after the anaphylactic reaction (T0). The analysis included untargeted metabolomics combining liquid chromatography coupled to mass spectrometry (LC-MS) and proton-nuclear magnetic resonance (1H-NMR). Reactions were classified according to the trigger (food and/or drug) and severity (moderate and severe). Results: “Food T1 vs T2” and “moderate T1 vs T2” anaphylaxis comparisons showed clear metabolic patterns during the onset of an anaphylactic reaction, which differed from those induced by drugs, food+drug or severe anaphylaxis “T1 vs T2”. Moreover, the model of food anaphylaxis was able to distinguish the well-characterized IgE (beta-lactam) from non-IgE- mediated anaphylaxis (NSAIDs), suggesting a differential metabolic pathway associated with the mechanism of action. Moreover, metabolic differences between “moderate vs severe” at T1 and T0 were studied. Among the metabolites, glucose, lipids, cortisol, betaine and oleamide were observed altered. Conclusions: The results of the study provide the first evidence that different anaphylactic triggers, induce differential metabolic changes. Besides, the basal status might identify high risk patients, thus opening new ways to understand, diagnose and treat anaphylaxis.
Project description:Background: Despite its increasing incidence, the underlying molecular processes of anaphylaxis remain unclear and there are not known biomarkers for appropriate diagnosis. The mechanism associated to the reactions still needs to be clarified in humans. The rapid onset and potentially fatal outcome in the absence of managed treatment, prevent its study and prompt obvious technical and ethical implications. Methods: Twenty episodes of anaphylaxis were analyzed. Sera was collected at different times: during the acute phase (T1), the recovery phase (T2) and around 2-3 months after the anaphylactic reaction (T0). The analysis included untargeted metabolomics combining liquid chromatography coupled to mass spectrometry (LC-MS) and proton-nuclear magnetic resonance (1H-NMR). Reactions were classified according to the trigger (food and/or drug) and severity (moderate and severe). Results: “Food T1 vs T2” and “moderate T1 vs T2” anaphylaxis comparisons showed clear metabolic patterns during the onset of an anaphylactic reaction, which differed from those induced by drugs, food+drug or severe anaphylaxis “T1 vs T2”. Moreover, the model of food anaphylaxis was able to distinguish the well-characterized IgE (beta-lactam) from non-IgE- mediated anaphylaxis (NSAIDs), suggesting a differential metabolic pathway associated with the mechanism of action. Moreover, metabolic differences between “moderate vs severe” at T1 and T0 were studied. Among the metabolites, glucose, lipids, cortisol, betaine and oleamide were observed altered. Conclusions: The results of the study provide the first evidence that different anaphylactic triggers, induce differential metabolic changes. Besides, the basal status might identify high risk patients, thus opening new ways to understand, diagnose and treat anaphylaxis.