Associations between specific IgE sensitization to 26 respiratory allergen molecules and HLA class II alleles in the EGEA cohort

In Silico Identification of Peanut Peptides Suitable for Allergy Immunotherapy in HLA-DRB1*03:01-Restricted Patients

Peanut allergy, a prevalent and potentially severe condition affecting millions worldwide, has been linked to specific human leukocyte antigens (HLAs), suggesting increased susceptibility. Employing an immunoinformatic strategy, we developed a "logo model" based on amino acid frequencies in the peptide binding core and used it to predict peptides originating from 28 known peanut allergens binding to HLA-DRB1*03:01, one of the susceptibility alleles. These peptides hold promise for immunotherapy in HLA-DRB1*03:01 carriers, offering reduced allergenicity compared to whole proteins. By targeting essential epitopes, immunotherapy can modulate immune responses with minimal risk of severe reactions. This precise approach could induce immune tolerance with fewer adverse effects, presenting a safer and more effective treatment for peanut allergy and other allergic conditions.

Prenatal Factors in the Development of Allergic Diseases

Allergic diseases are showing increasing prevalence in Western societies. They are characterized by a heightened reactivity towards otherwise harmless environmental stimuli. Allergic diseases showing a wide range of severity of symptoms have a significant impact on the quality of life of affected individuals. This study aims to highlight the mechanisms that induce these reactions, how they progress, and which prenatal factors influence their development. Most frequently, the reaction is mediated by immunoglobulin E (IgE) produced by B cells, which binds to the surface of mast cells and basophils and triggers an inflammatory response. The antibody response is triggered by a shift in T-cell immune response. The symptoms often start in early childhood with eczema or atopic dermatitis and progress to allergic asthma in adolescence. An important determinant of allergic diseases seems to be parental, especially maternal history of allergy. Around 30% of children of allergic mothers develop allergic sensitization in childhood. Genes involved in the regulation of the epithelial barrier function and the T-cell response were found to affect the predisposition to developing allergic disorders. Cord blood IgE was found to be a promising predictor of allergic disease development. Fetal B cells produce IgE starting at the 20th gestation week. These fetal B cells could be sensitized together with mast cells by maternal IgE and IgE-allergen complexes crossing the placental barrier via the low-affinity IgE receptor. Various factors were found to facilitate these sensitizations, including pesticides, drugs, exposure to cigarette smoke and maternal uncontrolled asthma. Prenatal exposure to microbial infections and maternal IgG appeared to play a role in the regulation of T-cell response, indicating a protective effect against allergy development. Additional preventive factors were dietary intake of vitamin D and omega 3 fatty acids as well as decreased maternal IgE levels. The effect of exposure to food allergens during pregnancy was inconclusive, with studies having found both sensitizing and protective effects. In conclusion, prenatal factors including genetics, epigenetics and fetal environmental factors have an important role in the development of allergic disorders in later life. Children with a genetic predisposition are at risk when exposed to cigarette smoke as well as increased maternal IgE in the prenatal period. Maternal diet during pregnancy and immunization against certain allergens could help in the prevention of allergy in predisposed children.

T-cell subsets in allergy and tolerance induction

Antigen-specific T lymphocytes are the central regulators of tolerance versus immune pathology against otherwise innocuous antigens and key targets of antigen-specific immune therapy. Recent advances in the understanding of T cells in tolerance and allergy resulted from improved technologies to directly characterize allergen-specific T cells by multiparameter flow cytometry or single-cell sequencing. This unravelled phenotypically and functionally distinct populations, such as Type 2a T helper cells (Th2a), follicular Th cells (Tfh), regulatory T cells (Treg), Type 1 regulatory T cells (Tr1), and follicular T regulatory cells. Here we will discuss the role of the different Th-cell subsets in the healthy state, during sensitization and development of allergy, and in tolerance induction by allergen immunotherapy (AIT). To date, the mechanisms of AIT as the only causal treatment of allergy are not completely understood. The analyses of allergen-specific T cells directly ex vivo during AIT support the concept of specific-Th2(a) cell deletion rather than an expansion of allergen-specific Tr1 or Treg cells as underlying mechanism.

Perspectives of Proteomics in Respiratory Allergic Diseases

Proteomics in respiratory allergic diseases has such a battery of techniques and programs that one would almost think there is nothing impossible to find, invent or mold. All the resources that we document here are involved in solving problems in allergic diseases, both diagnostic and prognostic treatment, and immunotherapy development. The main perspectives, according to this version, are in three strands and/or a lockout immunological system: (1) Blocking the diapedesis of the cells involved, (2) Modifications and blocking of paratopes and epitopes being understood by modifications to antibodies, antagonisms, or blocking them, and (3) Blocking FcεRI high-affinity receptors to prevent specific IgEs from sticking to mast cells and basophils. These tools and targets in the allergic landscape are, in our view, the prospects in the field. However, there are still many allergens to identify, including some homologies between allergens and cross-reactions, through the identification of structures and epitopes. The current vision of using proteomics for this purpose remains a constant; this is also true for the basis of diagnostic and controlled systems for immunotherapy. Ours is an open proposal to use this vision for treatment.

Associations between HLA class II alleles and IgE sensitization to allergens in the Qatar Biobank cohort

Background

Allergic disorders are the consequence of IgE sensitization to allergens. Population studies have shown that certain human leukocyte antigen (HLA) alleles are associated with increased or decreased risk of developing allergy.

Objective

We aimed to characterize the relationship between HLA class II allelic diversity and IgE sensitization in an understudied Arab population.

Methods

We explored associations between IgE sensitization to 7 allergen mixes and mesquite (comprising 41 food or aeroallergens) and 45 common classical HLA class II alleles in a well-defined cohort of 797 individuals representing the general adult population of Qatari nationals and long-term residents. To do so, we performed HLA calling from whole genome sequencing data at 2-field resolution using 2 independent algorithms. We then applied 3 different regression models to assess either each allergen mix independently, in the context of IgE sensitization to other allergens tested, or polysensitization.

Results

More than half (n = 447) of the study participants showed IgE sensitization to at least 1 allergen, most of them (n = 400) to aeroallergens (Phadiatop). We identified statistically significant negative and positive associations with 24 HLA class II alleles. These have been reported to confer risk or protection from variety of diseases; however, only a few have previously been associated with allergy in other populations.

Conclusions

Our study reveals several new risk and protective genetic markers for allergen-specific IgE sensitization. This is a first and essential step toward a better understanding of the origins of allergic diseases in this understudied population.

Immunoglobulin E-virus phenotypes of infant bronchiolitis and risk of childhood asthma

Background

Bronchiolitis is the leading cause of infant hospitalization in U.S. and is associated with increased risk for childhood asthma. Immunoglobulin E (IgE) not only plays major roles in antiviral immune responses and atopic predisposition, but also offers a potential therapeutic target.

Objective

We aimed to identify phenotypes of infant bronchiolitis by using total IgE (tIgE) and virus data, to determine their association with asthma development, and examine their biological characteristics.

Methods

In a multicenter prospective cohort study of 1,016 infants (age <1 year) hospitalized for bronchiolitis, we applied clustering approaches to identify phenotypes by integrating tIgE and virus (respiratory syncytial virus [RSV], rhinovirus [RV]) data at hospitalization. We examined their longitudinal association with the risk of developing asthma by age 6 years and investigated their biological characteristics by integrating the upper airway mRNA and microRNA data in a subset (n=182).

Results

In infants hospitalized for bronchiolitis, we identified 4 phenotypes: 1) tIgE^lowvirus^RSV-high, 2) tIgE^lowvirus^RSV-low/RV, 3) tIgE^highvirus^RSV-high, and 4) tIgE^highvirus^RSV-low/RV phenotypes. Compared to phenotype 1 infants (resembling "classic" bronchiolitis), phenotype 4 infants (tIgE^highvirus^RSV-low/RV) had a significantly higher risk for developing asthma (19% vs. 43%; adjOR, 2.93; 95% CI, 1.02-8.43; P=.046). Phenotypes 3 and 4 (tIgE^high) had depleted type I interferon and enriched antigen presentation pathways; phenotype 4 also had depleted airway epithelium structure pathways.

Conclusions

In this multicenter cohort, tIgE-virus clustering identified distinct phenotypes of infant bronchiolitis with differential risks of asthma development and unique biological characteristics.

A genome-wide association study for allergen component sensitizations identifies allergen component-specific and allergen protein group-specific associations

Background

Allergic diseases are some of the most common diseases worldwide. Genome-wide association studies (GWASs) have been conducted to elucidate the genetic factors of allergic diseases. However, no GWASs for allergen component sensitization have been performed.

Objective

We sought to detect genetic variants associated with differences in immune responsiveness against allergen components.

Methods

The participants of the present study were recruited from the Tokyo Children's Health, Illness, and Development study, and allergen component-specific IgE level at age 9 years was measured by means of allergen microarray immunoassays. We performed GWASs for allergen component sensitization against each allergen (single allergen component sensitization, number of allergen components analyzed, n = 31), as well as against allergen protein families (allergen protein group sensitization, number of protein groups analyzed, n = 16).

Results

We performed GWAS on 564 participants of the Tokyo Children's Health, Illness, and Development study and found associations between Amb a 1 sensitization and the immunoglobulin heavy-chain variable gene on chromosome 14 and between Phl p 1 sensitization and the HLA class II region on chromosome 6 (P < 5.0 × 10-8). A GWAS-significant association was also observed between the HLA class II region and profilin sensitization (P < 5.0 × 10-8).

Conclusions

Our data provide the first demonstration of genetic risk for allergen component sensitization and show that this genetic risk is related to immune response genes including immunoglobulin heavy-chain variable gene and HLA.

Tonsillar transcriptional profiles in atopic and non-atopic subjects

BACKGROUND

Emerging research suggests that local lymphatic tissue such as tonsils have important role in regulating the immune responses. However, allergen sensitization-induced alterations in transcriptome of tonsils are not known.

OBJECTIVES

To examine the key differences in tonsillar gene expression between atopic and non-atopic subjects and further by type of sensitization.

METHODS

RNA-sequencing was performed on 52 tonsillar samples from atopic and non-atopic tonsillectomy patients. Sensitization to common food- and aero-allergen was defined by allergen specific IgE. Following groups were studied: (1) aero- and food-allergen sensitized (AS+FS) versus non-sensitized (NS), (2) aeroallergen-sensitized (AS) versus food-allergen sensitized (FS), (3) AS versus NS, (4) FS versus NS. Bioinformatics analysis was done using DESeq2(v3.10.2), WGCNA and GATK pipeline in R software (v3.3.1). Protein-protein interaction network was made from String database.

RESULTS

We studied 13 aeroallergen-sensitized, 6 food-allergen sensitized, 4 both food-and aero-allergen-sensitized and 29 non-sensitized tonsillectomy patients. Overall, 697 unique differentially expressed genes (DEGs) were detected in all sensitized subgroups including chemokines (CXCL2, CXCL8, CXCL10, CXCL11), IL-20RA, MUC1 and MUC20. When comparing different groups, the gene expression profiles overlapped except the AS versus FS group comparison, suggesting significantly different gene expression between the two sensitization subgroups. Furthermore, aeroallergen-sensitized subjects had more prominent immune responses compared with non-sensitized and food-allergen sensitized subjects including gene expression for IL-17 pathway and Toll-like receptor signalling pathway.

CONCLUSION

Allergic sensitization is associated with extensive tonsillar transcriptomic alterations and changes in immune related genes and pathways. Distinct differences were found between aero-allergen and food-allergen sensitization.

Sensitisation to Pollen Allergens in Children and Adolescents of Different Ancestry Born and Living in the Same Area

Background

Allergy can start at early ages, with genetic and environmental factors contributing to its development.

Aim

The study aimed to describe the pattern of sensitisation and allergy in children and adolescents of Spanish versus Moroccan ancestry but born in the same rural area of Spain.

Methods

Participants were children and adolescents (3–19 years) of Spanish or Moroccan descent, born in Blanca, Murcia (Spain). A detailed questionnaire was completed, and skin prick tests were performed to assess reactions to the most prevalent pollen allergens (O. europaea, P. pratense, S. kali, C. arizonica, P. acerifolia, A. vulgaris and P. judaica) plus molecular components Ole e 1 and Ole e 7. The association with ancestry was verified by studying participants’ parents.

Results

The study included 693 participants: 48% were aged 3–9 years and 52%, 10–19 years; 80% were of Spanish descent and 20% of Moroccan descent. Sensitisation to Olea europaea, Phleum pratense, Salsola kali and Cupressus arizonica were slightly higher in the Spanish group. The only significant differences were observed in sensitisation to Ole e 1 (p=0.02). Rhinitis, conjunctivitis, and rhinitis plus asthma were significantly higher in the Spanish group (p=0.03, p=0.02, p=0.007, respectively). The sensitisation pattern differed between Spanish and Moroccan parents, and between Moroccan parents and their children, but not between Spanish parents and their children.

Conclusion

Both environment and ancestry may influence sensitisation and symptoms. Although the environment seems to have a stronger influence, other factors may contribute to the differences in prevalence and in the clinical entities in people of Spanish versus Moroccan descent.