Véronique Schulten

Previously undescribed grass pollen antigens are the major inducers of T helper 2 cytokine-producing T cells in allergic individuals

T cells play an important role in the pathogenesis of allergic diseases. However, the proteins considered as potential immunogens of allergenic T-cell responses have traditionally been limited to those that induce IgE responses. Timothy grass (TG) pollen is a well-studied inhaled allergen for which major IgE-reactive allergens have also been shown to trigger T helper 2 (Th2) responses. Here we examined whether other TG pollen proteins are recognized by Th2 responses independently of IgE reactivity. A TG pollen extract was analyzed by 2D gel electrophoresis and IgE/IgG immunoblots using pooled sera from allergic donors. Mass spectrometry of selected protein spots in combination with de novo sequencing of the whole TG pollen transcriptome identified 93 previously undescribed proteins for further study, 64 of which were not targeted by IgE. Predicted MHC binding peptides from the previoulsy undescribed TG proteins were screened for T-cell reactivity in peripheral blood mononuclear cells from allergic donors. Strong IL-5 production was detected in response to peptides from several of the previously undescribed proteins, most of which were not targeted by IgE. Responses against the dominant undescribed epitopes were associated with the memory T-cell subset and could even be detected directly ex vivo after Th2 cell enrichment. These findings demonstrate that a combined unbiased transcriptomic, proteomic, and immunomic approach identifies a greatly broadened repertoire of protein antigens targeted by T cells involved in allergy pathogenesis. The discovery of proteins that induce Th2 cells but are not IgE reactive may allow the development of safer immunotherapeutic strategies.

Association between specific timothy grass antigens and changes in TH1- and TH2-cell responses following specific immunotherapy

BACKGROUND Different populations of T cells are involved in the pathogenesis of allergic diseases. OBJECTIVE We investigated changes in TH-cell populations in patients with allergies after specific immunotherapy (SIT). METHODS PBMCs were isolated from patients with allergies who received SIT and those who did not (controls). We tested the ability of peptides from 93 timothy grass (TG) proteins to induce T-cell responses (cytokine production). We used ELISPOT and staining assays for intracellular cytokines to measure the production of IL-4, IL-5, IL-13, IFN-γ, and IL-10. RESULTS Compared with PBMCs from controls, PBMCs from patients who received SIT produced lower levels of TH2 cytokines on incubation with several different TG peptides. These data were used to select 20 peptides to be tested in an independent cohort of 20 patients with allergies who received SIT and 20 controls. We again observed a significant decrease in the production of TH2 cytokines, and an increase in the production of the TH1 cytokine IFN-γ, in PBMCs from the validation groups. These changes correlated with improved symptoms after SIT. Immunization with this selected pool of peptides (or their associated antigens) could protect a substantial proportion of the population from TG allergy. CONCLUSIONS We observed a significant decrease in the production of TH2 cytokines by PBMCs from patients who received SIT for TG allergy compared to those who did not. These changes might be used to monitor response to therapy. The decrease occurred in response to antigens that elicit little (if any) IgE responses; these antigens might be developed for use in immunotherapy.

Lack of allergy to timothy grass pollen is not a passive phenomenon but associated with the allergen-specific modulation of immune reactivity.

Timothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma.

17q21 asthma-risk variants switch CTCF binding and regulate IL-2 production by T cells.

Asthma and autoimmune disease susceptibility has been strongly linked to genetic variants in the 17q21 haploblock that alter the expression of ORMDL3; however, the molecular mechanisms by which these variants perturb gene expression and the cell types in which this effect is most prominent are unclear. We found several 17q21 variants overlapped enhancers present mainly in primary immune cell types. CD4+ T cells showed the greatest increase (threefold) in ORMDL3 expression in individuals carrying the asthma-risk alleles, where ORMDL3 negatively regulated interleukin-2 production. The asthma-risk variants rs4065275 and rs12936231 switched CTCF-binding sites in the 17q21 locus, and 4C-Seq assays showed that several distal cis-regulatory elements upstream of the disrupted ZPBP2 CTCF-binding site interacted with the ORMDL3 promoter region in CD4+ T cells exclusively from subjects carrying asthma-risk alleles. Overall, our results suggested that T cells are one of the most prominent cell types affected by 17q21 variants.

Transcriptional Profiling of Th2 Cells Identifies Pathogenic Features Associated with Asthma

Allergic asthma and rhinitis are two common chronic allergic diseases that affect the lungs and nose, respectively. Both diseases share clinical and pathological features characteristic of excessive allergen-induced type 2 inflammation, orchestrated by memory CD4+ T cells that produce type 2 cytokines (Th2 cells). However, a large majority of subjects with allergic rhinitis do not develop asthma, suggesting divergence in disease mechanisms. Because Th2 cells play a pathogenic role in both these diseases and are also present in healthy nonallergic subjects, we performed global transcriptional profiling to determine whether there are qualitative differences in Th2 cells from subjects with allergic asthma, rhinitis, and healthy controls. Th2 cells from asthmatic subjects expressed higher levels of several genes that promote their survival as well as alter their metabolic pathways to favor persistence at sites of allergic inflammation. In addition, genes that enhanced Th2 polarization and Th2 cytokine production were also upregulated in asthma. Several genes that oppose T cell activation were downregulated in asthma, suggesting enhanced activation potential of Th2 cells from asthmatic subjects. Many novel genes with poorly defined functions were also differentially expressed in asthma. Thus, our transcriptomic analysis of circulating Th2 cells has identified several molecules that are likely to confer pathogenic features to Th2 cells that are either unique or common to both asthma and rhinitis.

Different Bla-g T cell antigens dominate responses in asthma versus rhinitis subjects

The allergenicity of several German cockroach (Bla‐g) antigens at the level of IgE responses is well established. However, less is known about the specificity of CD4+ TH responses, and whether differences exist in associated magnitude or cytokine profiles as a function of disease severity.

Distinct modulation of allergic T cell responses by subcutaneous vs. sublingual allergen‐specific immunotherapy

Allergen‐specific immunotherapy is the only curative treatment for type I allergy. It can be administered subcutaneously (SCIT) or sublingually (SLIT). The clinical efficacy of these two treatment modalities appears to be similar, but potential differences in the immunological mechanisms involved have not been fully explored.

The Identification of Potentially Pathogenic and Therapeutic Epitopes from Common Human Allergens

OBJECTIVES To outline the processes involved in large-scale T-cell epitope identification from common allergens and illustrate their relevance to development of allergy specific immunotherapy. DATA SOURCES A set of studies recently published by our laboratory illustrating high-throughput identification of allergen specific T-cell epitopes. STUDY SELECTION T-cell responses contribute both directly and indirectly to allergy-related disease. However, the molecular targets (epitopes) recognized by allergen-specific T cells are largely undefined. We review several different studies in the last 2 years that identified novel T-cell epitopes from a panel of 32 different allergen sources. RESULTS Allergen-specific T-cell responses are highly heterogeneous. Epitopes prevalently recognized in allergic patients are often capable of binding to multiple HLA class II molecules. This feature can be used to predict these promiscuous epitopes by bioinformatic predictions. This approach was validated in the Timothy grass system and then applied to a panel of 31 other allergen sources. CONCLUSION T-cell epitopes for common allergens have been identified, and a general method to identify epitopes from additional allergens has been validated. Characterization of epitopes for common allergens might enable new diagnostics and immunotherapy regimens. These data will also allow the study of T-cell responses in different patient populations and throughout disease progression.

Immunoproteomic analysis of house dust mite antigens reveals distinct classes of dominant T cell antigens according to function and serological reactivity

House dust mite (HDM) allergens are a common cause of allergy and allergic asthma. A comprehensive analysis of proteins targeted by T cells, which are implicated in the development and regulation of allergic disease independent of their antibody reactivity, is still lacking.

Allergen-specific immunotherapy modulates the balance of circulating Tfh and Tfr cells

Abstract Follicular helper T cells (Tfh cells) are a CD4 T cell subset essential for germinal center formation and B cell responses, although their role in allergy and allergen-specific immunotherapy (AIT) is unclear. Here, we show that AIT-treated patients have a higher ratio of regulatory Tfh cells (Tfr) to follicular T cells (Tfh) and hypothesize an IL-2 dependent mechanism.