Sequencing of HLA-D in responders and nonresponders to short ragweed allergen, Amb a V

Allergic manifestations in autoimmune gastrointestinal disorders

Allergic disorders target a young population, are increasing in both incidence and prevalence and are associated with significant disease burden. They result from the complex interplay between (epi)genetic and environmental factors, resulting in a Th2 inflammatory process targeting the epithelium of the respiratory tract (allergic rhinitis and asthma), skin (atopic dermatitis), and gastrointestinal tract (food allergy). Although the exact pathogenic mechanisms remain elusive, an altered immune system response in the gut is increasingly recognized as a relevant step. Allergic and gastrointestinal autoimmune disorders share several epidemiological, pathogenic and risk factors and several treatment modalities. Here we revise the current literature and show that allergic disorders are highly prevalent in gastrointestinal autoimmune diseases, including celiac disease, inflammatory bowel disease, autoimmune pancreatitis, and autoimmune cholangiopathies. No data are available for some autoimmune diseases, such as autoimmune gastritis and autoimmune enteropathy. To ensure the comprehensive care of patients with autoimmune gastrointestinal disorders, along with disease-specific factors, the presence of allergic disorders should be evaluated and treated when present, possibly targeting shared molecular pathways. Future studies are needed to define the exact pathogenic mechanisms underpinning the association between allergic and autoimmune diseases of the gastrointestinal tract.

Human leukocyte antigen type and progression from onset of symptoms to development of asthma

This study investigated the influence of human leukocyte antigen (HLA) genes on the progression of asthma, from the initial onset of symptoms to when criteria for asthma are met. Study subjects were a subsample (n = 340) of 838 healthy children, aged 5-12 years, who participated in a previous study, and who had HLA data and asthma status. The duration in time from the initial onset of asthma symptoms documented in each subject's medical records to the index date when the subject first met criteria for asthma was determined. The time duration was compared between carriers and noncarriers of HLA genes of interest of the 340 original subjects with HLA data available, 114 children (33.5%) met criteria for asthma before 18 years of age. The median ages at onset of asthma symptoms and at the index date of asthma were 4.4 years and 7.2 years, respectively. The median time intervals between onset of symptoms and index date for HLA DRB1*11 carriers and noncarriers were 552 versus 61 days, respectively (p = 0.004). The same time intervals for HLA DQB1*0301 carriers and noncarriers were 420 versus 59 days, respectively (p = 0.012). However, HLA DQB1*0302 or DRB1*03 carriers had shorter median intervals, when compared with noncarriers (119 versus 266 days, respectively, p = 0.20; and 86 versus 258 days, respectively, p = 0.38) but they did not reach statistical significance. HLA type appears to influence the progression of asthma from initial symptoms to disease. Thus, genetic factors may affect the natural history of asthma.

The genetic and environmental basis of atopic diseases

The prevalence of atopic diseases has increased abruptly in recent years in most Westernized societies, making the question why this happened the topic of a heated debate. The best paradigm available to date to explain this steep rise, the 'hygiene hypothesis', supports that it is the excess 'cleanliness' of our environments that has led to the decline in the number of infectious stimuli that are necessary for the proper development of our immune system. Recent findings support that it is the combined effect that not only pathogenic, but also non-pathogenic microorganisms, and even their structural components,can exert on the immune system that deters from the development of atopic responses. Adding to these results are intriguing new findings on the effect different gene polymorphisms can have on an individual's predisposition to allergic diseases. The most important linkages produced, to date, include those among the genes for IL-4, IL-13, HLA-DRB, TNF, LTA,FCER1B, IL-4RA, ADAM33, TCR alpha/delta, PHF11, GPRA, TIM, p40, CD14, DPP10, T-bet, GATA-3, and FOXP3 and allergic disorders. The two parallel research efforts, epidemiologic and genetic, are only recently starting to converge,producing fascinating results on the effect particular gene-environment interactions might have in the development of atopy.The most important lesson learned through this tremendous research effort is that not only a small number but thousands and millions of separate risk factors act in concordance in the production of the allergic phenotype.

Severity of childhood asthma and human leukocyte antigens type

We sought to learn if Class II HLA genes are associated with the severity of asthma in children. We examined a previously recruited cohort of 340 healthy children who had Class II HLA allele data available. We conducted a comprehensive review of their medical records to determine asthma status and, when present, its severity. We found that Class II HLA alleles, which were previously reported to have an association with asthma incidence, appear to have an association as well with asthma severity. These data support our hypothesis that both the incidence and severity of asthma are heritable and that HLA may play an important role in both development and severity of asthma. Because of limited statistical power, our study findings are subject to further investigation.

Lack of correlation between regional pollen counts and percutaneous reactivity to tree pollen extracts in patients with seasonal allergic rhinitis

BACKGROUND

Although seasonal patterns of tree pollination have been reported, it is unknown if aerobiologic data correlate with patterns of in vivo sensitization.

OBJECTIVE

To evaluate the relationship between regional tree pollen exposure and patterns of in vivo percutaneous reactivity to specific tree pollen extracts in a local patient population with seasonal allergic rhinitis.

METHODS

Patients with spring seasonal allergic rhinitis and percutaneous sensitivity to 1 or more regional tree pollens were studied. Tree pollen counts were collected at the same urban site from 1997 to 2002 and at a suburban site in 2002. Patients underwent skin prick testing with commercial extracts of 15 indigenous tree species. Serum specific IgE measurements were assayed in a subset of sensitized patients.

RESULTS

Of 127 patients who reported symptoms consistent with seasonal allergic rhinitis during the spring pollen season, 93 qualified based on demonstration of at least 1 positive skin prick test result. Mean 5-year pollen counts (1997-2001) and 2002 urban counts were highly correlated (Spearman r = 0.95, P < .001), indicating that year-to-year pollen counts were consistent. No significant correlation was found between mean seasonal pollen counts (urban site, 1997-2001) and frequencies of skin prick test reactivity to specific tree pollen allergens (Spearman r = -0.03, P = .93). No significant relationship was found between 5-year mean tree pollen counts and positive serum specific IgE tests for specific tree pollens (Spearman r = -0.42, P = .30). Eight of 15 species elicited percutaneous reactions in more than 50% of patients (ie, satisfying definition of a major in vivo allergen). However, 6 of the 8 major tree allergens each represented 5% or less of 5-year mean total tree pollen counts.

CONCLUSION

No correlation was found between overall frequencies of in vivo sensitization to tree pollen allergens in a local population and regional pollen exposure data.

Requirements for allergen-induced airway inflammation and hyperreactivity in CD4-deficient and CD4-sufficient HLA-DQ transgenic mice

BACKGROUND

Airway inflammation is central to the pathogenesis of allergic asthma, and molecules that mediate this process obviously represent targets for therapy.

OBJECTIVE

To study the role of CD4(+) T cells and/or HLA-DQ molecules in allergic asthma, we have generated and characterized models of short ragweed allergen (SRW)-induced inflammation using transgenic mice with HLA-DQ (DQ6 or DQ8), human CD4 (hCD4), or both on a genetic background that lacks mouse MHC II and CD4 (Abeta(0)/mCD4(0)).

METHODS

Mice were actively sensitized and later challenged intranasally with SRW allergenic extract. Bronchoalveolar lavage fluid composition, airway inflammation and hyperresponsiveness, blood eosinophil levels, and cell proliferation were examined.

RESULTS

In response to SRW treatment, both DQ6 and DQ8 transgenic mice expressing hCD4 developed pulmonary eosinophilia and associated lung tissue damage with increase in eosinophil peroxidase and T(H)2 cytokines in bronchoalveolar lavage fluid, strong airway hyperreactivity, and persistent blood eosinophilia. The response was independent of mast cells/histamine pathway and was mediated by DQ-restricted hCD4(+) T cells. Interestingly, lungs of CD4-deficient DQ6 transgenic mice showed an eosinophilic inflammation without local increase in cytokines and eosinophil peroxidase. The allergic reaction was absent in double-knockout mice and mice expressing either DQ8 or hCD4 alone.

CONCLUSIONS

DQ6 molecules are critical to SRW-induced allergy and can operate in the presence or absence of CD4. However, both DQ antigens and CD4 molecules are critical for full manifestation of allergen-induced asthma in transgenic mice.

HLA class II transgenic mice as models of human diseases

Predisposition to develop various autoimmune disorders has been associated with certain HLA class II molecules but there is a lack of information on the pathophysiological role of HLA genes in conferring susceptibility. Various experimental animal models of autoimmune disease have been studied to address the role of immune response genes. To study the interactions involved between class II molecules (DQ and DR) and define the immunologic mechanisms in various diseases, we generated HLA-DR and DQ transgenic mice that lacked endogenous class II molecules. The HLA molecules in these mice are expressed on the cell surface and can positively select CD4+ T cells expressing various V beta T-cell receptors (TCR). A peripheral tolerance is maintained to transgenic HLA molecules thus indicating that these molecules act as self. Mouse co-stimulatory and accessory molecules can interact with the HLA-peptide-TCR complex leading to efficient T-cell activation. In this review, we describe immunogenetic models for human diseases using these transgenic mice. Our studies show that HLA class II transgene-restricted T cells recognize the immunodominant antigens and peptide epitopes, similar to HLA class II-restricted human T cells. Thus these mice provide powerful tools to understand the role of HLA class II molecules in predisposition and onset of human diseases and to develop immunotherapy and vaccines.

Genetic regulation of Dermatophagoides pteronyssinus-specific IgE responsiveness: a genome-wide multipoint linkage analysis in families recruited through 2 asthmatic sibs. Collaborative Study on the Genetics of Asthma (CSGA)

BACKGROUND

Dermatophagoides pteronyssinus (Der p) is one of the most frequently implicated allergens in atopic diseases. Although HLA could play an important role in the development of the IgE response to the Der p allergens, genetic regulation by non-HLA genes influences certain HLA-associated IgE responses to complex allergens.

OBJECTIVE

To clarify genetic control for the expression of Der p-specific IgE responsiveness, we conducted a genome-wide search for genes influencing Der p-specific IgE antibody levels by using 45 Caucasian and 53 African American families ascertained as part of the Collaborative Study on the Genetics of Asthma (CSGA).

METHODS

Specific IgE antibody levels to the Der p crude allergen and to the purified allergens Der p 1 and Der p 2 were measured. Multipoint, nonparametric linkage analysis of 370 polymorphic markers was performed with the GENEHUNTER program.

RESULTS

The best evidence of genes controlling specific IgE response to Der p was obtained in 2 novel regions: chromosomes 2q21-q23 (P = .0033 for Caucasian subjects) and 8p23-p21 (P = .0011 for African American subjects). Three regions previously proposed as candidate regions for atopy, total IgE, or asthma also showed evidence for linkage to Der p-specific IgE responsiveness: 6p21 (P = .0064) and 13q32-q34 (P = 0.0064) in Caucasian subjects and 5q23-q33 (P = 0.0071) in African American subjects.

CONCLUSIONS

No single locus generated overwhelming evidence for linkage in terms of established criteria and guidelines for a genome-wide screening, which supports previous assertions of a heterogeneous etiology for Der p-specific IgE responsiveness. Two novel regions, 2q21-q23 and 8p23-p21, that were identified in this study merit additional study.

Association of pyrazolone drug hypersensitivity with HLA-DQ and DR antigens

BACKGROUND

In sensitive patients pyrazolone drugs can precipitate adverse reactions ranging from urticaria and angioedema to anaphylactic shock, presumably by immunological, IgE-mediated mechanism. However, up to now no genetic factors influencing the development of allergic reaction have been reported in this type of hypersensitivity.

OBJECTIVE

The aim of our study was the investigation whether the susceptibility to development of pyrazolone drugs hypersensitivity (PDH) reactions was associated with HLA class II antigens.

METHODS

To test this hypothesis we studied the distribution of HLA-DR and DQ antigens in 26 pyrazolone sensitive patients and control groups including unselected general population and clearly defined atopic and non-atopic groups.

RESULTS

Significantly higher frequencies of DQ 7 and DR11 antigens were found in PDH group as compared with control unselected population (RR= 16.48, P < 0.0001; P(cor)< 0.002 and RR = 4.57, P = 0.0002; Pcor = 0.003 for DQ and DR antigen respectively). Similarly, statistically significant increased frequencies of DQ 7 and DR11 in patients with PDH were observed compared with atopic control group (RR= 18.43, P < 0.0001; Pcor <0.002 and RR= 6.33, P= 0.0007; Pcor =0.01, for DQ and DR antigen respectively). However, in comparison to non-atopic control group only the frequency of DQ 7 antigen was significantly increased (RR = 15.42, P = 0.0001; Pcor = 0.0015). DQ 7 antigen was present in 46.1% of PDH patients compared with 4.9%, 4.4% and 5.3% in the general population, atopic and non-atopic groups respectively, suggesting pyrazolone hypersensitivity as a trait positively correlated with this HLA antigen.

CONCLUSION

Our data suggest a genetic predisposition to pyrazolone hypersensitivity reactions, linked to HLA-DQ locus.

HLA-DQ6 and HLA-DQ8 Transgenic Mice Respond to Ragweed Allergens and Recognize a Distinct Set of Epitopes on Short and Giant Ragweed Group 5 Antigens

We have investigated the genetic and molecular basis of immune responsiveness to short ragweed (SRW) (Ambrosia artemisiifolia) extract, and group 5 allergens from short and giant (Ambrosia trifida) ragweed using transgenic mice expressing DQ6 (HLA-DQA1*0103, HLA-DQB1*0601) and DQ8 (HLA-DQA1*0301, HLA-DQB1*0302) genes in class II knockout (Aβ0) mice. Panels of overlapping peptides spanning the Amb a 5 and Amb t 5 Ags were synthesized. Mice were immunized with whole SRW extract or individual peptides s.c. and lymph node cells (LNC) were challenged in vitro. Strong T cell responses to SRW extract were measured in both HLA-DQ transgenic mice, while control, HLA-DQ6−/DQ8−/H-2Aβ0, mice were unresponsive. IL-5 and IL-10 were the primary cytokines produced by in vitro challenged LNC of SRW-primed transgenic mice. HLA-DQ6-restricted T cell responses were detected to all three peptides of Amb t 5 and two determinants (residues 1–20 and 11–30) on Amb a 5. In contrast, LNC of HLA-DQ8 mice did not recognize peptide 11–30 of Amb t 5 Ag, but recognized several Amb a 5 determinants. The immune response in transgenic mice was dependent upon CD4+ T cells and was HLA-DQ restricted. Primed with purified Amb t 5, both transgenics recognized peptide 21–40, and an additional DQ6-restricted epitope was found within residue 1–20. SRW-immunized HLA-DQ6 mice respond to peptide 11–30 of Amb a 5, while HLA-DQ8 mice strongly recognize peptide 1–20. These results demonstrate the specificity of HLA class II polymorphism in allergen sensitivity and pave the way for developing antagonistic peptides for desensitization.

Association of responsiveness to the major pollen allergen of Parietaria officinalis with HLA-DRB1* alleles: a multicenter study

Parietaria, a plant belonging to the family of Urticaceae, is a major source of allergenic pollen in Europe. In the context of a multinational study, we investigated whether in allergic subjects antibody response towards Par o 1, the major allergen from P. officinalis, was associated with defined HLA-DRB1* alleles. The study population consisted of 234 allergic patients: 65 from Bulgaria, 30 from Israel, 99 from Italy, and 40 from Spain. In the Italian study group, the prevalence of ST positivity to Parietaria was 77%. In Parietaria ST-positive subjects, the prevalences of IgG and IgE serum Ab towards Par o 1 were 91% and 75%, respectively. HLA-DRB1*1101 and/or 1104 were significantly positively associated with the presence of IgG Ab and with high levels of IgE Ab towards this allergen (p = 0.0007 and p = 0.012, respectively). In the Spanish study group, the positive association of DR1100 with responsiveness to Par o 1 was confirmed (p = 0.02, RR = 4, and p = 0.002, RR = 7, for IgG and IgE Ab, respectively). None of the Bulgarian patients had IgE Ab to Par o 1, whereas IgG Ab response was observed in 7 out of 65 subjects and was positively associated with DRB1*1101 and/or 1104 (p = 0.025). In the Israeli study group, responsiveness to Par o 1 was not associated with specific HLA-DRB1* alleles. In conclusion, this study shows that in allergic patients from three European populations antibody response to the major allergen from the pollen of Parietaria is associated with HLA-DRB1*1101 and/or 1104. Our data suggest that this association is stronger in subjects monosensitized to Parietaria.

Association of class II sequences encoding DR1 and DQ5 specificities with hypersensitivity to chironomid allergen Chi t I

A panel of 188 unrelated Caucasian subjects who were exposed to the larvae of Chironomus thummi (Diptera, nonbiting midges) was HLA-typed by polymerase chain reaction amplification of the second exons of the DRB, DQA1, and DQB1 genes followed by dot-blot hybridization with sequence-specific oligonucleotide probes. Type I sensitization to the allergen Chi t I and a large number of other inhalant allergens was determined by RAST and skin testing. Sixty-one individuals were found to be sensitized to Chi t I, of whom 24 were sensitive to this allergen and to no other allergens tested. Statistical analyses showed that only in the latter group were the HLA-D genes DRB1*0101, DQA1*0101, and DQB1*0501 associated with IgE-responsiveness to Chi t I. These results suggest that HLA associations with responsiveness to certain allergens may be more striking in monosensitized subjects.

DR7 and DQ2 are positively associated with immunoglobulin-E response to the main antigen of olive pollen (Ole e I) in allergic patients

We have studied the relationship between HLA class II haplotypes and alleles, and the IgE antibody response to a highly purified allergen, Ole e I, in allergic patients. Ole e I, is the major antigen from the pollen of olive tree that grows mainly in the Mediterranean. Genomic DNA typing was performed in 40 unrelated patients with seasonal allergic pollenosis who had specific IgE antibodies against Ole e I, detected by double-antibody radioimmunoassay. HLA-DRB and -DQB loci were analyzed by PCR-SSO and RFLP. Phenotypic frequencies were compared with those of 179 healthy unrelated individuals. Significant increases in the phenotypic frequencies of DR7 (pf = 67.5% vs 31.3% in the control population, pc = 0.0023) and DQ2 (pf = 90.0% vs 48.0%, pc = 0.0003) were found, indicating an association between DRB1*0701/2, DQB1*0201 alleles and the IgE antibody response to Ole e I. This is the first time that the HLA-DQ gene has been associated with a positive allergic response.

Genetic analysis of the linkage between chromosome 11q and atopy

Previous work has suggested that there is a genetic predisposition for the development of both asthma and atopy. A recent study has also shown that there is a striking link between chromosome 11q and the IgE response underlying asthma and rhinitis. To further assess the linkage between chromosome 11q and atopy, we have studied nine families of two and, in many instances, three generations with the index case having asthma and/or atopy. Using two restriction fragment length polymorphism probes associated with the regions 11q12-q13.2, namely PYGM and INT2, we have been unable to confirm a significant link between this region of chromosome 11q and atopy as defined by a positive skin-prick test and/or a raised specific IgE and/or a raised total IgE.

Genetic analysis of atopy in three large kindreds: no evidence of linkage to D11S97

Both genetic and environmental influences have been implicated in the pathogenesis of atopic disease. A recent report suggested that a major gene providing susceptibility to atopy was transmitted in a pattern consistent with autosomal dominant inheritance and evidence was presented that places the disease locus near the D11S97 marker on human chromosome 11q. In this report, we present three large, highly characterized pedigrees in which atopy is transmitted in a pattern consistent with autosomal dominant inheritance. Genotypes at the D11S97 and HLA loci were evaluated using both lod score and sib pair methods of analysis. In these pedigrees, we reject close moderate linkage (up to 10 cM) of atopy with both D11S97 and HLA.

A novel HLA-haplotype containing a DRB5 gene not associated with DRB1*15 or DRB1*16 alleles

In Caucasians, HLA-DR2 haplotypes usually express two DRB genes encoding the DR specificity. The DRB5 genes are in strong linkage disequilibrium with the respective DRB1*15 or DRB1*16 alleles. So far, no other DRB1 alleles have been found in association with DRB5 genes. Here, we report evidence for a probably recombinant DRB5 haplotype with a DRB1 allele not specific for DR2. From our results the haplotype DQB1*0501, DRB1*0101 and DRB5*0101 seems most likely.

Class II major histocompatibility complex restriction of human T cell responses to short ragweed allergen, Amb a V

Although T cells are known to play a crucial role in the induction of IgE synthesis, the class II major histocompatibility complex (MHC) restriction of aeroallergen-induced T cell responses in humans is incompletely defined. We have previously shown that, in allergic Caucasoid individuals, HLA-DR2 and Dw2 (DR2.2) is strongly associated with specific IgE and IgG antibody responses to highly purified Ambrosia (ragweed) allergen, Amb a V, from the artemisiifolia (short) species. For example, 95% of IgE antibody responders to Amb a V were typed as DR2.2. In a novel study of the genetic control of T cell responses to the Amb a V allergen, we have investigated the MHC class II restriction specificity of three CD4, Amb a V-specific T cell clones derived from a DR2.2+ atopic patient, and a polyclonal Amb a V-reactive T cell line from another DR2.2+ patient. We observed proliferative responses of all three clones to Amb a V only when either HLA-DR2.2 or DR2, Dw12 (DR2.12; found on Mongoloid populations) was present on the antigen-presenting cells, regardless of the HLA-DQ phenotype of the cells. Moreover, the responses of T cell line and clones were abolished by anti-DR but not by anti-DQ nor by anti-DP monoclonal antibodies, and, significantly, anti-DR alpha/beta I2 (anti-DR alpha /beta Iw15/w16; anti-"DR2b") monoclonal antibody blocked, in a dose-dependent manner, the cloned T cell responses to Amb a V. These findings demonstrate that DR alpha/beta I2.2 (DR alpha/beta I1501) and DR alpha/beta I2.12 (DR alpha/beta I1502) are functional in the restriction of the T cell recognition of Amb a V. These findings also illustrate the power of the allergy model for definitive investigation of the molecular basis of the human immune response.

Cloning the cDNA encoding the AmbtV allergen from giant ragweed (Ambrosia trifida) pollen

Ragweed (Ambrosia) pollens contain a number of proteins that cause allergic disease in ragweed-sensitive people. The cloning of the AmbtV cDNA is important, since the 4.4-kDa AmbtV, one of the allergens in giant ragweed (Ambrosia trifida) pollen, serves as a simple model system to study the basic structural requirements for immune recognition of foreign protein allergens. We report the cloning of the AmbtV cDNA by means of the polymerase chain reaction (PCR) using degenerate primers. We generated three sets of overlapping cDNA clones by a combination of PCR and anchored-PCR, and determined the complete nucleotide (nt) sequence. From the nt sequence, the amino acid (aa) sequence of the protein was confirmed and the leader sequence was deduced. This general approach can be used to clone allergen and other cDNAs from complex biological sources provided partial aa sequence information is available. It may be the best available approach in cases where the isolation of clones from a cDNA library is difficult, which proved to be the case for AmbtV.

HLA-D gene studies in relation to immune responsiveness to a grass allergen Lol p III

The grass pollen allergen Lol p III (Mr 11,000) is a well-characterized antigen that has been found useful in immunogenetic studies of human immune responsiveness. Since immune responsiveness to this allergen is associated with HLA-DR3, we investigated whether there was any sequence in the HLA-D region that would render a person "susceptible" [antibody (Ab)-positive] to the allergen. By sequence-specific oligonucleotide (SSO) slot-blot and sequence analyses of polymerase chain reaction (PCR)-amplified genomic DNA from Lol p III responder and nonresponder subjects, Ab responsiveness was found to be strongly associated with the sequence Glu-Tyr-Ser-Thr-Ser (EYSTS), present in the first polymorphic regions of DR beta I polypeptide chains of DR3, DR11 (split of DR5), and DRw6. Of the 41 grass-allergic subjects investigated, 19 had the EYSTS sequence, of whom 18 (95%) were Lol p III immunoglobulin G (IgG) Ab responders; among the 22 EYSTS- subjects, ten were Lol p III responders (P = 0.001, relative risk = 21.6). No such association was found with any polymorphic sequences in other DR beta chains, or in DQ alpha I and DQ beta I chains. These findings suggest that the EYSTS sequence is important in the presentation of an epitope of Lol p III; other sequence(s) may be involved in the presentation of other epitope(s). To our knowledge, this is the first demonstration of a strong association between a specific HLA sequence and immune responsiveness to a well-defined antigen. The paper shows that presence of the EYSTS sequence classifies subjects as Lol p III responders in 18/19 cases.