Devonshire, A. | bioRxiv Science

bioRxiv2023

B cell repertoire in children with skin barrier dysfunction supports altered IgE maturation associated with allergic food sensitization

IgE B cells produce antibodies responsible for the inappropriate specificity seen in allergic disease. In this study, we sequence antibody gene repertoires from a large, well-characterized early life cohort at risk for developing food allergy. We found that food allergen sensitization was associated with lower IgE mutation frequencies that was abrogated in children living with a pet dog, suggesting potential molecular mechanisms underlying the hygiene hypothesis (i.e., protective effects of pet ownership and non-antiseptic environs reported for allergic disease). We also observed increased IgE diversity and increased isotype-switching to IgE, suggesting that B cell development is altered in those with food allergen sensitizations relative to those without. IgE diversity was even more extreme in subjects who were highly likely to be peanut allergic. Unlike food antigen sensitization, we detected no effect of aeroallergen sensitization on IgE mutation levels and diversity. Consistent patterns of antibody rearrangement were associated with food allergen sensitization. These results have important implications for the allergic response driven by mast cells and basophils and the underlying drivers of the atopic march.

immunology↗

bioRxiv2021

Epigenetic and Transcriptional Dysregulation in CD4+ T cells of Patients with Atopic Dermatitis

Atopic dermatitis (AD) is one of the most common skin disorders in children. Disease etiology involves genetic and environmental factors, with the 29 independent AD risk loci enriched for risk allele-dependent gene expression in the skin and CD4+ T cell compartments. We investigated epigenetic mechanisms that may account for genetic susceptibility in CD4+ T cells. To understand gene regulatory activity differences in peripheral blood T cells in AD, we measured chromatin accessibility (ATAC-seq), NFKB1 binding (ChIP-seq), and gene expression (RNA-seq) in stimulated CD4+ T cells from subjects with active moderate-to-severe AD and age-matched, non-allergic controls. Open chromatin regions in stimulated CD4+ T cells were highly enriched for AD genetic risk variants, with almost half of AD risk loci overlapping with AD-dependent ATAC-seq peaks. AD-specific open chromatin regions were strongly enriched for NF{kappa}B DNA binding motifs. ChIP-seq identified hundreds of NFKB1-occupied genomic loci that were AD-specific or Control-specific. As expected, the AD-specific ChIP-seq peaks were strongly enriched for NF{kappa}B DNA binding motifs. Surprisingly, Control-specific NKFB1 ChIP-seq peaks were not enriched for NFKB1 motifs, instead containing motifs for other classes of human TFs, suggesting a mechanism involving altered indirect NFKB1 binding. Using DNA sequencing data, we identified 63 instances of genotype-dependent chromatin accessibility at 36 AD risk variants (30% of AD risk loci) that could lead to genotype-dependent expression at these loci. We propose that CD4+ T cells respond to stimulation in an AD-specific manner, resulting in disease and genotype-dependent chromatin accessibility involving NFKB binding. AUTHOR SUMMARYStimulated CD4+ T cells from patients with atopic dermatitis have disease-dependent regulation of how gene expression is regulated. This regulation is disease dependent and the way the DNA is accessible and the transcription factor NFKB1 binds is enriched for genetic risk variants. Clinically, the CD4+ T cells in the peripheral blood of patients with AD respond to stimulation in a disease and genotype-dependent manner.

genomics↗