Contribution of the microbiome, environment, and genetics to mucosal Type 2 immunity and anaphylaxis in a murine food allergy model

Abstract

Murine models of food allergy are useful tools for identifying potential pathways involved in the manifestation of anaphylactic reactions to food in humans. Individual mice exhibit inherent heterogeneity in their immune responses, including anaphylaxis, much like what is seen clinically in food allergic humans. The microbiome (MB) may be one major driver of this difference in individuals. MB dysbiosis by broad spectrum antibiotics and/or yeast colonization can alter systemic immunity and favor the development of mucosal Type 2 immunity to aeroallergens. Our objective was to use a well-characterized murine model of food allergies (chicken egg ovalbumin, OVA) and determine if dysbiosis could enhance the manifestation of food allergies and identify elements of the MB and host response associated with this heterogeneity. In our dataset, the intensity of anaphylaxis was most strongly associated with a disrupted MB that included C. albicans colonization, loss of a specific Lachnoclostridium species, development of a highly polarized Type 2 response in the intestines, and activation of mucosal mast cells. OVA-specific IgE serum levels were not predictive of the response and in germ-free mice the response was not fully recapitulated. Conventionalization of germ-free mice resulted in Akkermansia muciniphila outgrowth and more heterogeneity in the allergic response. We also observed that housing environment could induce MB changes that altered the response. Thus, our data recapitulate the heterogeneity in anaphylactic reactions, ranging from severe to none, seen in patients with circulating levels of food allergen-specific IgE and support the idea that alterations in the MB can be one factor underlying this heterogeneity. Supported by grants from NIH NIAID R01AI138348, Mary H. Weiser Food Allergy Center (MHWFAC), and the Nina and Jerry D. Liptak Endowment of the MHWFAC