Epigenetic mechanisms in the development of peanut/tree nut allergy

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

Epigenetic changes are key regulatory mechanisms of gene expression. In subproject B2, we aim to unravel the impact of the DNA methylome on peanut/tree nut allergy. In a cross sectional study, we compare the methylome of allergic patients recruited in the clinical project A2 with non-allergic controls in order to find determinants of peanut/tree-nut allergy. Our longitudinal approach comparing the methylation patterns before and after the dietary intervention study of A2 will identify changes in the methylome underlying tolerance development and potential predictors of treatment response.In the first funding period, we performed a proof of principle analysis on peripheral blood mononuclear cells (PBMCs). We have established the complete experimental workflow from PBMC isolation and DNA/RNA extraction to methylation profiling including data processing, association analyses and functional assessment of differentially methylated positions and regions (DMPs and DMRs). Although due to COVID 19 pandemic this study was performed in a reduced data set, we identified 1 DMP at genome-wide significance and a number of candidate DMPs and DMRs which could be linked to immune-related functions. Interestingly, two of the candidate DMRs are supported by a previous methylation study on IgE sensitization. In addition to the work program, we have established an in vitro cell stimulation protocol using peanut and hazelnut to investigate allergen-specific differences in DNA methylation and gene transcription. Indeed, the results of the cross-sectional analysis revealed both overlapping and distinct methylation-differences between peanut/tree nut allergic individuals in unstimulated and stimulated PBMCs, indicating an effect of allergen-specific stimulation on DNA methylation.The main focus of the second funding period is on the analysis of the methylome in specific subpopulations of PBMCs. By using subpopulations, methylation differences between allergic and non-allergic individuals should be more pronounced and cell-type specific immune mechanisms will be detected. We will investigate CD4+ and CD8+ T-cells, both of which have been shown to be involved in the allergic response and tolerance development. In addition, we will complete the longitudinal analysis which will be extended by the analysis of methylation differences arising upon PBMC stimulation with allergen-specific extract. Both approaches, the analysis of PBMC subpopulations and their allergen-specific stimulation, will strengthen the identification of immune mechanisms involved in peanut/tree nut allergy and tolerance induction. Finally, the identified DMRs will be analyzed jointly with other KFO projects regarding their role as mediators of environmental factors such as the microbiome, their involvement in shaping immunological phenotypes, and their potential interaction with miRNA expression.

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