Single-cell characterization of dog allergen–specific T cells reveals TH2 heterogeneity in allergic individuals

Abstract

Background: Allergen-specific type 2 CD4 1 T H 2 cells are critically involved in the pathogenesis of IgE-mediated allergic diseases. However, the heterogeneity of the T H 2 response has only recently been appreciated. Objective: We sought to characterize at the single-cell level the ex vivo phenotype, transcriptomic profile, and T-cell receptor (TCR) repertoire of circulating CD4 1 T cells specific to the major dog allergens Can f 1, Can f 4, and Can f 5 in subjects with and without dog allergy. Methods: Dog allergen-specific memory CD4 1 T cells were detected ex vivo by flow cytometry using a CD154-based enrichment assay and single-cell sorted for targeted gene expression analysis and TCR sequencing. Results: Dog allergen-specific T-cell responses in allergic subjects were dominantly of T H 2 type. T H 2 cells could be phenotypically further divided into 3 subsets, which consisted ofcells. All these subsets were nonexistent within the allergen-specific T-cell repertoire of healthy subjects. Single-cell transcriptomic profiling confirmed the T H 2-biased signature in allergen-specific T cells from allergic subjects and revealed a T H 1/T H 17 signature in nonallergic subjects. TCR repertoire analyses showed that dog allergen-specific T cells were diverse and allergic subjects demonstrated less clonality compared to nonallergic donors.Finally, TCR and transcriptomic analyses revealed a close relationship between T H 2-like, T H 2, and T H 2A cells, with the last ones representing the most terminally differentiated and highly polarized subtype. Conclusions: Our study demonstrates heterogeneity within allergen-specific T H 2 cells at the single-cell level. The results may be utilized for improving immune monitoring after allergen immunotherapy and for designing targeted immunomodulatory approaches. (J Allergy Clin Immunol 2021;nnn:nnn-nnn.)

Th2A cells: The pathogenic players in allergic diseases

“…In the meantime, Morgan et al found that Th2A cells are enriched in esophageal tissue from EoE patients and associated with the recruitment of eosinophils to the esophageal tissue, indicating that Th2A cells are the pathogenic cells for EoE (38). A recent study by Vandamme et al using TCR and transcriptomic analysis of dog allergen-specific T cell responses in allergic subjects revealed a close relationship between Th2-like, Th2, and Th2A cells (39).…”

“…A recent study by Vandamme et al. using TCR and transcriptomic analysis of dog allergen–specific T cell responses in allergic subjects revealed a close relationship between Th2-like, Th2, and Th2A cells ( 39 ).…”

T helper cell subsets: diversification of the field

“…These cells have been coined Th2A cells [34]. These allergen‐reactive Th2‐biased Th cells with increased pathogenicity and terminal differentiation as well as reduced clonality can also be identified in individuals with allergies, as recently shown for dog allergen‐reactive T cells by single‐cell RNA sequencing [35].…”

T‐cell subsets in allergy and tolerance induction

“…In 2017, Wambre et al identified Th2a cells, which express a terminally differentiated CD4 + memory phenotype characterized by CD161+CD27-CrTh2+CD49d+ expression and appear to carry the Th2 memory cell function over a long time [18][19][20]. On allergen stimulation, these Th2a cells secrete high amounts of IL-4, IL-13, IL-9, and IL-5 [18], which can be further increased by epithelium-derived IL-33 [21].…”