Food allergy versus tolerance – direction by antigen specific immunologic reactivity

• Applicant: Professorin Dr. Margitta Worm
• Subject Area: Clinical Immunology and Allergology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 409525714

Allergen-specific adaptive immune cells are pivotal for induction and maintenance of allergy including food allergy. However, their function and fate during desensitization is not yet well understood. Therefore, we aim at identification, characterization and monitoring of allergen-specific T and B cells in well-defined food allergic, but also food sensitized and tolerant individuals in cooperation with A1 and A2.In the 1st funding period (FP), we developed stable and reproducible experimental systems to assess allergen-specific lymphocytes. Using in vitro stimulation with allergen followed by staining of T cell activation markers CD40L (CD154) and 4-1BB (CD137) as well as cytokines and transcription factors, we detected allergen-specific T cells and categorized them into helper T cell subgroups (Th1, Th2, Th17, etc.), T follicular helper cells and regulatory T cells (Tregs). Dual-color antigen staining was employed to measure allergen-specific B cells. The allergen-specific T and B cells are monitored in the course of dietary intervention to link phenotypic changes to cellular alterations. However, due to the pandemia-associated delays in patient recruitment, the number of pairs of pre- and post-intervention samples are as yet insufficient to draw definite conclusions about their role in desensitization. However, by applying clustering analyses with allergen-specific T and B cells, we could stratify donor samples into healthy and allergic. In addition, we determined the abundance and phenotype of allergen-specific T and B cells following oral food challenge in a kinetic experiment. Hereby, we determined that at day 7 T cells are reduced in peripheral blood, likely due to tissue homing, while B cells proliferate after challenge. In allergic donors, predominantly Th2 cells proliferate, while in healthy more Th1 and Th17 cells react.In the 2nd FP, we will continue monitoring of T and B cells in the clinical study participants. Further, we will assess whether there is a clonality bias in the changes of allergen-specific lymphocytes after oral food challenge and track their fate during dietary intervention. To this end, we will analyze sorted allergen-specific lymphocytes by single-cell RNA sequencing. The analysis of samples from donors before and after intervention will enable us to link cellular alterations to therapeutic success. We have recently described CD3 downregulation as a proxy for high T cell receptor affinity in the context of anti-viral immunity and want to extend these insights to food allergy by assessing CD3 downregulation in allergen-reactive T cells. In cooperations, we will aide B2 and B5 with sorting specific cell subsets that may be source cells of target miRNAs or to enhance epigenetic resolution. Also, we will characterize the subtypes of Ig-coating of fecal microbiota in cooperation with B1.By these experimental approaches, we will broaden the understanding of the role of adaptive immunity in food allergy and tolerance.

• DFG Programme: Clinical Research Units
• Subproject of: KFO 339: Food Allergy and Tolerance (Food@)
• Co-Investigator: Professor Dr. Andreas Thiel