Allergy to olive pollen: T-cell response from olive allergic patients is restricted by DR7-DQ2 antigens

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

BACKGROUND

Allergy, the most frequent immune disorder affecting 30% of the world's population, is the consequence of immunoglobin E (IgE) sensitization to allergens. Among the genetic factors suspected to be involved in allergy, the HLA class-II genomic region is a strong candidate.

OBJECTIVE

To assess the association between HLA class-II alleles and specific IgE (sIgE) sensitization to a large number of respiratory allergen molecules.

METHODS

The analysis relied on 927 participants of the EGEA cohort, including 497 asthmatics. The study focuses on 26 aeroallergens recognized by sIgE in at least 5% of the study population (determined with the MEDALL chip with sIgE ≥ 0.3 ISU) and 23 imputed HLA class-II alleles. For each sIgE sensitization and HLA class-II allele, we fitted a logistic regression model accounting for familial dependence and adjusted for gender, age, and genetic principal components. p-values were corrected for multiple comparisons (False Discovery Rate).

RESULTS

Most of the 19 statistically significant associations observed regard pollen allergens (mugwort Art v 1, olive tree Ole e 1, timothy grass Phl p 2, Phl p 5 and plantain Pla l 1), three were mold allergen (Alternaria Alt a 1), and a single one regards house dust mite allergen (Der p 7). No association was observed with pet allergens. The strongest associations were found with mugwort Art v 1 (OR = 5.42 (95%CI, 3.30; 8.88), 4.14 (2.65; 6.47), 3.16 (1.88; 5.31) with DQB1*05:01, DQA1*01:01 and DRB1*01:01, respectively).

CONCLUSION

Our results support the important role of HLA class-II alleles as immune response genes predisposing their carriers for sensitization to various major pollen allergens.

A Role for IL-10-Mediated HLA-DR7-Restricted T Cell-Dependent Events in Development of the Modified Th2 Response to Cat Allergen

Although high dose exposure to inhaled cat allergen (Fel d 1) can cause a form of tolerance (modified Th2 response), the T cell mechanism for this phenomenon has not been studied. T cell responses to Fel d 1 were characterized in both allergic (IgE(pos)) and modified Th2 (IgE(neg)IgG(pos)) responders as well as serum Ab-negative controls (IgE(neg)IgG(neg)). Fel d 1 stimulated high levels of IL-10 in PBMC cultures from all individuals, with evidence of Th2 and Th1 cytokine skewing in allergic and control subjects, respectively. Using overlapping peptides, epitopes at the N terminus of Fel d 1 chain 2 were shown to stimulate strong T cell proliferation and to preferentially induce IL-10 (peptide 2:1 (P2:1)) or IFN-gamma (P2:2) regardless of the allergic status of the donor. Injection of cat extract during conventional immunotherapy stimulated expansion of IL-10- and IFN-gamma-producing chain 2 epitope-specific T cells along with increased Fel d 1-specific serum IgG and IgG4 Ab. Six of 12 modified responders expressed the major HLA-DRB1 allele, *0701, and both P2:1 and P2:2 were predicted ligands for this allele. Cultures from DR7-positive modified responders produced the highest levels of IL-10 to P2:1 in addition to other major and minor epitopes within chains 1 and 2. In the presence of anti-IL-10 mAb, both T cell proliferation and IFN-gamma production were enhanced in a Fel d 1- and epitope-specific manner. We conclude that IL-10-producing T cells specific for chain 2 epitopes are relevant to tolerance induction, and that DR7-restricted recognition of these epitopes favors a modified Th2 response.

HLA class II genotypic frequencies in atopic asthma: association of DRB1*01-DQB1*0501 genotype with Artemisia vulgaris allergic asthma

Different human leukocyte antigen (HLA) class II alleles have been associated with the development of atopic asthma. To determine whether HLA class II alleles are associated with atopic asthma in a population from southeast Spain (Murcia region), 213 atopic asthmatic patients and 150 controls were selected for HLA typing. Significant association of the DRB1*01 and DQB1*0501 alleles was found in Artemisia vulgaris allergic patients (p(c) = 0.00052 and p(c) = 0.00023, respectively). No significant correlation was found in other atopic patients allergic to pollens (Phleum pratense, Olea europaea, and Salsola kali), house dust mites (Dermatophagoides pteronyssinus, D. farinae), molds (Alternaria alternata, Cladosporium herbarum), or animal danders (dog, cat). The results reveal that the DRB1*01-DQB1*0501 genotype is strongly associated with a positive response to Artemisia vulgaris in the population studied.

Genetic restrictions in olive pollen allergy

BACKGROUND

The major antigen of olive tree pollen, Ole e 1, produces an IgE response restricted by DQ2.

OBJECTIVE

Our purpose was to further analyze the genetic restrictions associated with IgE and IgG antibodies against Ole e 1 and IgE against the recently described antigen Ole e 3.

METHODS

Twenty-two nuclear olive pollen-allergic families (n = 88) were selected. DRB1 and DQB1, TCR-Valpha 8.1, the high-affinity receptor of IgE (FcepsilonRI-beta) Rsa I exon 7 and intron 2 and TNF-beta (LTalpha-Nco I) polymorphisms were determined by PCR and analyzed for association with allergic traits by the multiallelic transmission disequilibrium test.

RESULTS

Significant associations were found among HLA-DQB1*0201 (n = 29) and high levels of IgG (P =.023) and IgE (P =.0136) antibodies to Ole e 1 and with IgE specific to Ole e 3 (P =.0368). DRB1*0701 was associated with high levels of total serum IgE (P =.04) and IgG against Ole e 1 (P =.025). The FcepsilonRI-beta Rsa I exon 7, allele 1 (n = 39), was associated with high levels of total serum IgE (P =. 01), IgE antibodies against Olea europaea extract (P =.004), and specific antibodies to Ole e 1, IgG (P =.04), and IgE (P =.006). The FcepsilonRI-beta Rsa I intron 2, allele 2 (n = 33), was associated with IgE antibodies to O europaea extract (P =.003) and specific antibodies to Ole e 1, IgG (P =.025), and IgE (P =.05).

CONCLUSIONS

We found a new association between IgE antibody response to Ole e 3 and DQB1*0201 and verified the previously reported association between Ole e 1-specific response and DQB1*0201. Also, the association between FcepsilonRI-beta and IgE antibodies against Ole e 1 was demonstrated.

HLA class II polymorphism in cystic fibrosis. A possible modifier of pulmonary phenotype

Evolution of lung damage is highly variable in cystic fibrosis (CF) even in patients with the same cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The analysis of genetic factors other than CFTR may help our understanding of genotype-phenotype relationships in CF. As human leukocyte antigen (HLA) class II polymorphism has been associated with a number of diseases including autoimmune and inflammatory diseases, asthma, and allergy, we investigated the possibility that HLA polymorphism contributes to CF-associated pulmonary inflammation. Among the 98 adult CF patients tested, the genotypic frequencies of DR4 and DR7 alleles (serologic group DR53) and DR7/ DQA*0201 haplotype were higher than in 39 selected control subjects without atopy (p </= 10(-)6, relative risk [RR] = 22, and p </= 5.10(-)4, RR = 27, respectively) and in a random population. No significant difference of these allelic distributions was found according to the CFTR genotype. In the CF patients, the DR7 allele was significantly associated with an increase in total IgE and with chronic Pseudomonas aeruginosa colonization (100% of DR7 versus 83% of non-DR7 patients being colonized, p < 0.05). Our results suggest that genetic factors known to modulate the immune response might contribute to chronic infection with Pseudomonas, increased total IgE, and pulmonary outcome in CF.

Galectin-3 Down-Regulates IL-5 Gene Expression on Different Cell Types

Galectin-3 is an animal lectin, formerly named ε-binding protein or Mac-2, which has been described to play an important role in some inflammatory processes by the implication of different cells and the increase in cell adhesion functions through laminin binding activity. In this work we analyzed the role of galectin-3 in the modulation of Th2 cytokines that have an important role in the development of the inflammatory response. We have found that the addition of galectin-3 to human eosinophils, the eosinophilic cell line EoL-3, PBMC, and an Ag-specific T cell line (CD4+) produced a selective inhibition of IL-5 transcription. No inhibitory effect was found on the IL-4 mRNA transcription rate. The inhibitory effect on IL-5 transcription was reversed by incubation with lactose and using specific Ab against galectin-3. Galectin-3 is able to induce inhibition of the IL-5 released in the supernatants from PBMC stimulated with phorbol 12,13-dibutyrate and anti-CD3. Similar results were obtained when a T-specific cell line was stimulated with Ag. Also, EoL-3 stimulated with anti-CD32 produced IL-5 protein, the synthesis of which was partially inhibited by galectin-3. The present results demonstrate that galectin-3 induces a selective down-regulation of IL-5 expression in different cell types, opening important new possibilities in the regulation of the allergic reactions.

Olive pollen allergy: searching for immunodominant T-cell epitopes on the Ole e 1 molecule

BACKGROUND

The amino-acid and nucleotide sequence of Ole e 1 (the major antigen of olive pollen) has been described and the IgE antibody response to this major allergen was associated with DR7/DQ2 antigens. With this previous data we try to define the T-cell epitopes implicated in Ole e 1 reactivity.

OBJECTIVES

To study the recognition of T cells (derived from allergic and non-allergic Ole e 1 patients) to Ole e 1 synthetic peptides in order to define immunodominant T-cell epitopes.

METHODS

We have compared the proliferative response of the peripheral blood mononuclear cells from Ole e 1 sensitized patients vs. non-sensitized controls, induced by 14 Ole e 1 synthetic peptides. Thirty subjects were classified in two groups: group 1 (non-responders against Ole e 1, n=16) and group 2 (Ole e 1 responders, n=14), according to their clinical parameters and the presence or not in their sera of the significant Ole e 1 IgE antibody levels.

RESULTS

Our results shown that it is possible to find T cells reactive to Ole e 1 peptides in patients with and without significant levels of Ole e 1 IgE antibodies. However, the percentage of response was higher in patients with IgE antibodies 71.4% vs 25%), and the recognition profile was different: the control group showed a broad reactivity pattern, in contrast, the response by the 'Ole e 1 responders' group was mainly directed against three peptides of the carboxi-terminal region, peptides 10 (91-102), 12 (109-120) and 13 (119-130), with a response frequency of 35.7, 28.5 and 28.5%, respectively. By direct and inhibition test no antibody response was found against the synthetic peptides.

CONCLUSIONS

Our data suggest that the regions between 91 and 102 and 109-130 aminoacids on the Ole e 1 molecule are immunodominant T-cell epitopes. These epitopes are not recognized by IgE antibodies.

HLA class II DRB1, DQB1 and DPB1 genotypic associations with peanut allergy: evidence from a family-based and case-control study

BACKGROUND

Peanut is one of the most common foods provoking allergic reactions and is the most frequent cause of fatal and near-fatal food-induced anaphylaxis. However, as yet, little is known of the genetic and immunological mechanisms which underly peanut allergy.

OBJECTIVE

Based on findings in other allergic diseases, we have investigated whether particular human leucocyte antigen (HLA) class II genetic polymorphisms contribute to the development of peanut allergy.

METHODS

All individuals from 37 families each containing one or more peanut allergic individuals, plus nine unrelated patients (161 individuals in total, defined as the study group) were typed for the HLA class II DRB1, DQB1 and DPB1 loci, by PCR-based techniques. Genotype frequencies were compared with those found in 293 unrelated controls.

RESULTS

Four class II genotypes (DRB1*08 (13.7% vs 4.8%; Pc = 0.026), DRB1*08/12 tyr 16 (22.4% vs 8.2%; Pc = 0.021), DQB1*04 (12.2% vs 2.7%; Pc = 0.0026) and DPB1*0301 (49.1 vs 22.5%; Pc = 0.00062)) were present at a significantly higher frequency in the study group compared with controls. Three of these genotypes (DRB1*08 (18.0%; Pc = 0.027), DRB1*08/12 tyr16 (24.0%; Pc = 0.029) and DQB1*04 (16.7%; Pc = 0.0029)) were also significantly increased in peanut allergic individuals compared with controls. In addition, two genotypes (DPB1*0101 and 0201) were significantly decreased in frequency in the overall study group, but not specifically in peanut allergic individuals.

CONCLUSION

While other genetic factors may be important, results from this study indicate that HLA class II genetic polymorphism may play a role in determining susceptibility to peanut allergy.

Cloning and expression of the panallergen profilin and the major allergen (Ole e 1) from olive tree pollen

BACKGROUND

Olive tree (Olea europaea) pollen allergy is one of the main causes of allergy in Mediterranean countries and some areas of North America.

OBJECTIVE

To clone olive allergens and to characterize immunologically the purified recombinant allergens.

METHODS

Full-length complementary deoxyribonucleic acid (cDNA) strands encoding olive allergens (Ole e 1) were cloned by polymerase chain reaction amplification and sequenced. Recombinant proteins were produced in Escherichia coli by the use of two different expression systems. Immunoreactivity of the recombinant proteins was tested by ELISA and Western blot with serum from patients with allergy to olive.

RESULTS

Significant sequence polymorphism was found in both allergens. The panallergen profilin was expressed as a nonfusion protein and was purified to homogeneity after a single step of affinity chromatography with a poly-L-proline Sepharose column. One cDNA encoding an Ole e 1 isoform was expressed as a fusion protein consisting of the glutathione S-transferase of Schistosoma japonicum and Ole e 1. The fusion protein was purified to homogeneity by gel filtration chromatography and affinity chromatography with a glutathione-Sepharose column, and digested with thrombin. Both recombinant allergens shared B cell epitopes with the corresponding natural allergens.

CONCLUSION

IgE-reactive Ole e 1 and olive profilin expressed in bacteria were purified after simple chromatographic procedures and may be useful for diagnostic purposes.

Antigenicity of the pollen proteins of various cultivars of Olea europaea

The incidence of positive skin test responses among atopic subjects with suspected respiratory allergy was investigated with commercial and autochthonous pollen extracts of various cultivars of Olea europaea. Pollen was collected from olive trees of well-defined cultivars, extracted, and separated by SDS-PAGE. Immunoblots were used to identify the various IgE-binding proteins of the pollen extracts of the various cultivars. The results revealed six predominant IgE-binding bands, some of which appear in all the cultivars examined. The 18-20-kDa band (Ole e 1) appeared in only eight of the cultivars, but not in the nine others. The presence of specific IgE-binding bands in the various pollen extracts and their correlation with the incidence of positive skin tests are discussed.

Hypersensitivity to pollen of Olea europaea in Israel

The incidence of skin-tested sensitivity to olive pollen allergens among subjects with suspected atopic respiratory allergy was investigated in various populations of Israelis. This incidence was correlated with the olive cultivars, with the abundance of trees in the patient's neighborhoods, and with the history of exposure of the studied populations to olive pollen. Positive skin reactions to olive pollen, among atopic patients of the Jewish population, is rather high where olive trees are abundant (66%), and lower (29%) where trees are scarce (P < 0.003). Sensitization was significantly lower (P < 0.003) among a population of Israeli atopic Arabs (16%), though these Arabs have lived in an olive-rich area for several generations.