Molecular Pathways Modulating the Severity of IgE-mediated Anaphylaxis

Abstract

Food allergic reactions can involve cardiovascular, respiratory, cutaneous, gastrointestinal (GI) and neurologic organ systems. Clinical and experimental studies have provided corroborative evidence that upon food exposure, dietary antigens cross-link the IgE- FceRI complex on mast cells (MC) and basophils surface to stimulate the release of mediators that drive the clinical manifestations of food allergy. However, the cellular and molecular processes that contribute to the organ involvement and severity of the reaction are unknown. Herein, we define: 1) the interaction between the cytokine Interleukin-4 (IL-4) and histamine in the regulation of vascular endothelial (VE) barrier function; 2) IL-4 receptor a (IL4Ra) / Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathways in the regulation of VE barrier function; 3) the role of MC-derived mediators in the GI symptoms of food-induced anaphylaxis in mice. We show that IL-4 increased histamine-induced fluid extravasation, and this increase positively correlated with anaphylaxis severity in mice. Genetic deletion of the IL-4Ra chain on VE cells showed that IL-4-enhancement of histamine and IgE/MC-induced anaphylaxis symptoms were dependent on the VE IL-4Ra chain. Mechanistically, we show that IL-4 enhanced histamine-induced VE ABL1 activation. IL-4-enhancement and histamine-induced VE barrier dysfunction, histamine-induced anaphylaxis and hypovolemia were ABL1 dependent. Collectively, these data implicate an important contribution by the VE compartment in the severity of IgE-mediated anaphylaxis. We next show that IL-4 enhancement of histamine-induced VE barrier dysfunction in VE cells was associated with histamine-mediated VE-Cadherin degradation. The enhancement of histamine-induced VE barrier dysfunction was dependent on IL-4-induced gene transcription. RNAseq analyses revealed enrichment of differentially expressed genes (DEGs) that possessed a putative STAT3 motif. In silico and in vitro approaches identified an IL-4-induced and STAT3 dependent VE transcriptome that was characterized by barrier integrity and signaling genes. Indeed, IL-4-induced exacerbation of histamine- or anti IgE mAb- induced anaphylaxis was in part STAT3-dependent. Collectively, these data implicate an important role of the IL-4/ STAT3 signaling axis in the priming of VE cells, which results in modulating the severity of IgE-and histamine-induced anaphylaxis. Finally, we defined the intestinal epithelial response during a food-induced anaphylaxis. We show that oral allergen challenge stimulates a rapid dysregulation of intestinal epithelial transcellular and paracellular transport that was associated with the development of secretory diarrhea. Allergen-challenge induced a rapid intestinal epithelial CFTR-dependent Cl- secretory response, and a paracellular macromolecular leak that was associated with modification in epithelial adherence and tight junction proteins. Blockade of both the proteolytic activity and Cl- secretory response was required to alleviate intestinal symptoms of food-induced anaphylaxis. Collectively, these data suggest that the GI symptom of food-induced anaphylactic reaction, secretory diarrhea, is a consequence of CFTR-dependent Cl- secretion and proteolytic activity. Collectively, these studies have unveiled a role for the IL-4-STAT3-histamine axis in dysregulation of VE barrier function of the systemic symptoms of food-induced anaphylaxis, and MC-derived proteases in the regulation of the GI symptoms of food-induced anaphylaxis.