A role for glycolipids and unconventional T cell subsets in alpha-gal allergy

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Project Summary/Abstract This proposal seeks to expand our understanding of the mechanisms driving alpha-gal syndrome (AGS) and to provide a strong foundation for the applicant, Dr. Onyinye Iweala, to build an independent basic and translational research career. The candidate is an Assistant Professor of Medicine, tenure track, at the University of North Carolina-Chapel Hill (UNC) School of Medicine and a member of the Thurston Arthritis Research Center and the UNC Food Allergy Initiative. The proposed project expands on her previous training in mucosal immunology, weaving together the fields of mucosal immunity with glycolipid biology and allergic effector cell biology in the context of a paradigm-shifting food allergy. Through formal coursework outlined in the proposal and with help from her mentorship team, led by primary mentors Scott Commins and Wesley Burks, the candidate will develop the technical and administrative skills needed to run a successful basic and translational research enterprise. In the process, she will develop a unique skillset that will enhance her ability to compete successfully for R01 grants and comparable funding mechanisms available through government agencies and private foundations. AGS is an exciting area of food allergy ripe for discovery. By studying this condition, the candidate will cultivate her interest in mucosal immunity and develop new expertise in glycolipid biology during her transition from a mentored to an independent investigator. Alpha-gal syndrome, characterized by delayed allergic responses to red meat (mammalian meat), is a novel allergic condition associated with tick bites and specific IgE antibody to the oligosaccharide galactose-α-1,3- galactose (alpha-gal). Alpha-gal food allergy challenges the current paradigm for food allergy because reactions are usually delayed, appearing >2 hours following meat ingestion; IgE antibodies are against a carbohydrate rather than a protein; and the allergy can develop in adulthood after many years of safely tolerating red meat. The lipid content of ingested meat appears to impact reaction consistency and severity, leading many to theorize that alpha-gal in glycolipid form is a critical driver of symptoms in this allergy. However, no one has shown that alpha-gal-specific (s)IgE can bind alpha-gal glycolipids or that alpha-gal glycolipids can activate allergic effector cells. Innate or unconventional T lymphocyte populations, specifically CD1d-restricted invariant natural killer T (iNKT) cells, bind glycolipid antigens complexed with CD1d and direct immune responses to lipid. Yet, the extent to which this T cell population drives alpha-gal allergy remains unexplored. Our preliminary results suggest that alpha-gal-sIgE binds mammalian glycolipids and that alpha-gal glycolipids can activate basophils sensitized with plasma containing alpha-gal-sIgE. Moreover, activated circulating CD1d-restricted NKT cells are detectable in alpha-gal allergic subjects. Thus, we hypothesize that alpha-gal glycolipids are critical to the pathogenesis of alpha-gal syndrome, through CD1d-mediated interactions with unconventional T cells and through IgE-Fc epsilon receptor (FcRI)-mediated interactions with allergic effector cells.