Biology and genetics of atopic disease

From the outside-in: Epidermal targeting as a paradigm for atopic disease therapy

Atopic dermatitis (AD) is a chronic inflammatory skin disorder which can precede asthma and allergic rhinitis in a disease trajectory known as the atopic march. The pathophysiology of AD includes cutaneous inflammation, disrupted epidermal barrier function, xerosis and propensity to secondary infections. AD had previously been thought to arise from the systemic atopic immune response and therapies are therefore directed towards ameliorating Th2-mediated inflammation. However in recent years the focus has shifted towards primary defects in the skin barrier as an initiating event in AD. Links between loss-of-function variants in the gene encoding filaggrin and disrupted activity of epidermal serine proteases and AD have been reported. Based on these observations, a mechanism has been described by which epidermal barrier dysfunction may lead to inflammation and allergic sensitization. Exogenous and endogenous stressors can further exacerbate inherited barrier abnormalities to promote disease activity. Pathways underlying progression of the atopic march remain unclear, but recent findings implicate thymic stromal lymphopoietin as a factor linking AD to subsequent airway inflammation in asthma. This new appreciation of the epidermis in the development of AD should lead to deployment of more specific strategies to restore barrier function in atopic patients and potentially halt the atopic march.

Role of Ca/CaN/NFAT signaling in IL-4 expression by splenic lymphocytes exposed to phthalate (2-ethylhexyl) ester in spleen lymphocytes

The aims of present study were to investigate the effect of phthalate (2-ethylhexyl) ester (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP) on Th1/Th2 balance signaling for interleukin 4 (IL-4) expression in splenic lymphocytes, and contribution of MEHP to any hypothesized changes in vitro. Primary splenic lymphocytes were exposed to DEHP/MEHP. ELISA and Western blotting were used to detect proteins. Confocal-microscopy was used to examine nuclear translocation. Nuclear factor of activated T cells (NFAT) DNA binding activity was examined by electrophoretic mobility-shift assay. DEHP significantly increased IL-4 and interferon gamma (IFN-γ) level, and reduced Th1/Th2 ratio (reflected by IFN-γ/IL-4) with 5 μg/L Concanavalin A (ConA) treatment. While MEHP reduced Th1/Th2 ratio (represented by IFN-γ/IL-6). IL-4 mRNA was significantly increased by DEHP but not by MEHP after PMA and Ion treatment. DEHP significantly inhibited NFATp protein in cytosol and nucleus. DEHP augmented nuclear translocation of NFATc in transfected EL4 cells and NFAT DNA-binding activity. DEHP-mediated enhancement of calcium-dependent phosphatase calcineurin (CaN) protein, and NFAT and IL-4 expression were abrogated by calcium antagonist verapamil and CaN inhibitor tarcolimus. Ca(2+)/calmodulin antagonist chlorpromazine significantly suppressed IL-4 and CaN production with no NFAT mRNA change. Our study suggests that DEHP and MEHP impact Th1/Th2 balance by modulating different cytokines. DEHP-affected IL-4 expression through Ca/CaN/NFAT signaling pathway, but no effect was discovered for MEHP.

Pollen aero allergens and the climate in Mediterranean region and allergen sensitivity in allergic rhinoconjunctivitis and allergic asthma patients

BACKGROUND

We evaluated the profiles of allergic rhino-conjunctivitis and asthma patients annually in Antalya, a Mediterranean coastal city in Turkey.

MATERIAL AND METHODS

We evaluated patients' allergic clinical status, and recorded the climate and pollens in the city center air, investigating any correlation between pollination, climatic conditions and allergic disorders. The meteorological conditions and the pollen count/cm2 during every month of the year and the concordance of this with the patient's clinical status were evaluated.

RESULTS

SPT positivity for plantago lanceolata, aspergillus fumigatus and d. pteronyssinus was significant in patients younger than 40 years old. Pollination levels are consistent from March 2010 to February 2011. In Antalya, high levels occur mostly from April to June, thus we performed skin prick tests mostly in May/June (~30%). During these months meteorological conditions of the city were windy with low humidity, without rain, and lukewarm temperatures, all of which contribute to high-risk conditions for seasonal allergies.

CONCLUSIONS

The major allergen between April and June was derived from Graminea; between February and March was Cupressus spp; and between March and June was Pinus spp. These results suggest that the pollination is correlated with allergic conditions and thus SPT might be best performed according to the pollen count.

Accuracy of protein allergenicity prediction can be improved by taking into account data on allergenic protein discontinuous peptides

Allergy poses major health problems in industrialized countries, affecting over 20% of the population. Proteins from transgenic foods, cosmetics, animal hair, and other ubiquitous sources can be allergens. For this reason, development of improved methods for the prediction of potential allergenicity of proteins is timely. The currently available approaches to allergenicity prediction are numerous. Some approaches relied heavily on information on protein three-dimensional (3D) structure for allergenicity prediction. They required knowledge about 3D structure of query protein, thereby considerably restricting analysis to only those proteins whose 3D structure was known. As a consequence, many proteins with unknown structure could be overlooked. We developed a new method for allergenicity prediction, using information on protein 3D structure only for training. Three-dimensional structures of known allergenic proteins were used for representing protein surface as patches designated as discontinuous peptides. Allergenicity was predicted through search of such peptides in query protein sequences. It was demonstrated that the information on the discontinuous peptides made feasible better prediction of allergenic proteins. The allergenicity prediction method is available at http://www-bionet.sscc.ru/psd/cgi-bin/programs/Allergen/allergen.cgi .

A synonymous variation in protease-activated receptor-2 is associated with atopy in Korean children

BACKGROUND

Atopic diseases are the most common chronic diseases of childhood, and the genetics of atopy are complex and heterogeneous. Protease-activated receptor-2 (PAR-2) is involved in various inflammatory diseases, but the association of PAR-2 with allergic diseases remains unclear.

OBJECTIVE

To examine the contribution of genetic variation of PAR-2 to atopic phenotypes in the Korean childhood cohort.

METHODS

We identified PAR-2 variations in a Korean population and conducted association analyses by using 316 unrelated atopic and 210 nonatopic subjects. We analyzed serum IgE and total eosinophil count levels and examined PAR-2 mRNA and protein expression levels.

RESULTS

In the case-control association analysis, atopy was significantly associated with a single c.621C>T (p.I207I, rs631465) polymorphism of PAR-2 (P = .001, odds ratio = 1.95). Subjects with the c.621T risk allele had significantly higher serum IgE (P = .004) and total eosinophil count (P = .03) levels. Moreover, the positive association of c.621T was reproduced in the replication study (P = .01, joint P value of the replication < .001). An in silico analysis of RNA secondary structure prediction revealed that the C to T conversion at c.621 greatly increased predicted PAR-2 mRNA stability. This was also confirmed by an in vitro assay for mRNA stability. Furthermore, following an in vivo approach on gene expression in PBMCs showed that the expression levels of PAR-2 mRNA and protein in subjects with the c.621CT or TT genotype were significantly higher than in those with the c.621CC genotype.

CONCLUSIONS

These results indicate that the synonymous c.621C>T polymorphism in PAR-2 might be associated with the risk of atopy, potentially by altering PAR-2 gene expression.

Diagnosis of Chenopodium album allergy with a cocktail of recombinant allergens as a tool for component-resolved diagnosis

Chenopodium album pollen is one of the main sources of pollen allergy in desert and semi-desert areas and contains three identified allergens, so the aim of this study is comparison of the diagnostic potential of C. album recombinant allergens in an allergenic cocktail and C. album pollen extract. Diagnostic potential of the allergenic cocktail was investigated in 32 individuals using skin prick test and obtained results were compared with the acquired results from C. album pollen extract. Specific IgE reactivity against the pollen extract and allergenic cocktail was determined by ELISA and western blotting tests. Inhibition assays were performed for the allergenic cocktail characterization. The exact sensitization profile of all patients was identified which showed that 72, 81 and 46% of allergic patients had IgE reactivity to rChe a 1, rChe a 2 and rChe a 3, respectively. Almost all of C. album allergic patients (30/32) had specific IgE against the allergenic cocktail. In addition, there was a high correlation between IgE levels against the allergenic cocktail and IgE levels against the pollen extract. The allergenic cocktail was able to completely inhibit IgE binding to natural Che a 1, Che a 2 and Che a 3 in C. album extract. In addition, positive skin test reactions were seen in allergic patients that tested by the allergenic cocktail. The reliable results obtained from this study confirmed that the allergenic cocktail with high diagnostic potential could be replaced with natural C. album allergen extracts in skin prick test and serologic tests.

The proline-rich N-terminal sequence of calcineurin Abeta determines substrate binding

Three different genes of catalytic subunit A of the Ca(2+)-dependent serine/threonine protein phosphatase calcineurin (CaN) are encoded in the human genome forming heterodimers with regulatory subunit B. Even though physiological roles of CaN have been investigated extensively, less is known about the specific functions of the different catalytic isoforms. In this study, all human CaN holoenzymes containing either the alpha, beta, or gamma isoform of the catalytic subunit (CaN alpha, beta, or gamma, respectively) were expressed for the first time. Comparative kinetic analysis of the dephosphorylation of five specific CaN substrates provided evidence that the distinct isoforms of the catalytic subunit confer substrate specificities to the holoenzymes. CaN alpha dephosphorylates the transcription factor Elk-1 with 7- and 2-fold higher catalytic efficiencies than the beta and gamma isoforms, respectively. CaN gamma exhibits the highest k(cat)/K(m) value for DARPP-32, whereas the catalytic efficiencies for the dephosphorylation of NFAT and RII peptide were 3- and 5-fold lower, respectively, when compared with the other isoforms. Elk-1 and NFAT reporter gene activity measurements revealed even more pronounced substrate preferences of CaNA isoforms. Moreover, kinetic analysis demonstrated that CaN beta exhibits for all tested protein substrates the lowest K(m) values. Enzymatic characterization of the CaN beta(P14G/P18G) variant as well as the N-terminal truncated form CaN beta(22-524) revealed that the proline-rich sequence of CaN beta is involved in substrate recognition. CaN beta(22-524) exhibits an at least 4-fold decreased substrate affinity and a 5-fold increased turnover number. Since this study demonstrates that all CaN isoforms display the same cytoplasmic subcellular distribution and are expressed in each tested cell line, differences in substrate specificities may determine specific physiological functions of the distinct isoforms.

AllerHunter: a SVM-pairwise system for assessment of allergenicity and allergic cross-reactivity in proteins

Allergy is a major health problem in industrialized countries. The number of transgenic food crops is growing rapidly creating the need for allergenicity assessment before they are introduced into human food chain. While existing bioinformatic methods have achieved good accuracies for highly conserved sequences, the discrimination of allergens and non-allergens from allergen-like non-allergen sequences remains difficult. We describe AllerHunter, a web-based computational system for the assessment of potential allergenicity and allergic cross-reactivity in proteins. It combines an iterative pairwise sequence similarity encoding scheme with SVM as the discriminating engine. The pairwise vectorization framework allows the system to model essential features in allergens that are involved in cross-reactivity, but not limited to distinct sets of physicochemical properties. The system was rigorously trained and tested using 1,356 known allergen and 13,449 putative non-allergen sequences. Extensive testing was performed for validation of the prediction models. The system is effective for distinguishing allergens and non-allergens from allergen-like non-allergen sequences. Testing results showed that AllerHunter, with a sensitivity of 83.4% and specificity of 96.4% (accuracy = 95.3%, area under the receiver operating characteristic curve AROC = 0.928+/-0.004 and Matthew's correlation coefficient MCC = 0.738), performs significantly better than a number of existing methods using an independent dataset of 1443 protein sequences. AllerHunter is available at (http://tiger.dbs.nus.edu.sg/AllerHunter).

Class B beta-expansins are needed for pollen separation and stigma penetration

Group 1 grass pollen allergens comprise a distinctive clade within the beta-expansin family of cell wall-loosening proteins and are divided by sequence divergence into two phylogenetically separable classes (A and B). They have been proposed to loosen the walls of the stigma and style. Supporting this idea, we recently showed that a transposon insertion in one of the maize group-1 allergen genes reduces the ability of pollen to effect fertilization under conditions of pollen competition. In this work, we provide additional information on the phenotype of this mutant, showing that pollen deficient in beta-expansin gene expression tended to form large aggregates, leading to poor pollen dispersal on anther dehiscence, and that emerging pollen tubes had difficulties entering the silk. In addition, a silencing construct was created to reduce expression of all the class B genes with results that are consistent with those seen with the transposon insertional line, including reduced transgene transmission through the pollen. Our results provide a more detailed understanding of the role of group 1 allergens (pollen beta-expansins) in maize pollen development, pollen dispersal, pollen tube penetration into the style, and pollen tube growth through the transmitting tract.

Molecular and immunological characterization of novel weed pollen pan-allergens

BACKGROUND

Pan-allergens like profilins, calcium-binding proteins (CBPs), and nonspecific lipid transfer proteins have been suggested as possible specific markers for multiple pollen sensitizations, and could be used to predict cross-sensitization/poly-sensitization to several pollen allergens. Therefore, the purification and characterization of cross-reacting allergens in pollen is an extremely important task towards correct allergy diagnosis.

METHODS

New pan-allergens were identified by screening a ragweed pollen cDNA library with sera of patients allergic to mugwort pollen. Resulting proteins were cloned, expressed, purified and characterized.

RESULTS

We report complete cDNA sequences of two profilin isoforms (Amb a 8.01 and Amb a 8.02), two isoforms of a 2EF-hand CBP (Amb a 9.01 and Amb a 9.02), a new 3EF-hand CBP (Amb a 10) from ragweed pollen and a 2EF-hand CBP from mugwort (Art v 5). All these proteins were expressed in Escherichia coli, purified to homogeneity and characterized by biochemical and immunological means.

CONCLUSIONS

The identified proteins are novel pan-allergens and can be used as diagnostic markers for polysensitization and used in component-resolved diagnosis.

The DR4-DQ8 haplotype and a specific T cell receptor Vbeta T cell subset are associated with absence of allergy to Can f 1

BACKGROUND

The significance of specific T cell receptor (TCR) Vbeta subtypes and human leucocyte antigen (HLA) class II alleles for the development of allergy to lipocalin allergens such as the major dog allergen Can f 1 is not clear at present.

OBJECTIVE

To characterize the TCR Vbeta usage in the Can f 1-specific T cell lines and the HLA class II genotypes of Can f 1-allergic and non-allergic subjects.

METHODS

T cell lines were induced with recombinant Can f 1 from the peripheral blood mononuclear cells of 12 non-atopic dog owners and 26 dog-allergic patients. Thirteen of the dog-allergic subjects were sensitized to Can f 1. Expression of the TCR Vbeta subtypes on CD4(+) T cells in the T cell lines was measured by flow cytometry. The subjects were HLA genotyped for DRB1, DQB1 and DPB1 loci.

RESULTS

Can f 1-specific T cell lines were obtained from 18 subjects, with either positive (n=8) or negative (n=10) skin prick tests (SPTs) to recombinant Can f 1. The frequency of TCR Vbeta5.1(+) T cells was significantly higher in the T cell lines of subjects with negative SPTs to the allergen. Moreover, DR4-DQ8 haplotype was over-represented among these subjects.

CONCLUSION

The DR4-DQ8 haplotype and the TCR Vbeta5.1(+) CD4(+) T cells may be protective against allergy to Can f 1.

Fucoidan prevents C epsilon germline transcription and NFkappaB p52 translocation for IgE production in B cells

Fucoidan, a dietary fiber contained in seaweed, reduces the increase of antigen-specific IgE in mice exposed to ovalbumin. In this study, we investigated the effect of fucoidan on IgE production and intracellular events in B cells in vitro. Fucoidan inhibited the production of IgE and C epsilon germline transcription in murine B cells induced by IL-4 (100 ng/ml) and anti-CD40 antibodies (10 microg/ml), whereas it stimulated cell proliferation. A significant effect of fucoidan on IgE production was observed when B cells were stimulated with a higher dose (5 microg/ml) of anti-CD40 antibodies, but not when stimulated with lower doses (1.25, 2.5 microg/ml), regardless of the IL-4 concentrations. Moreover, nuclear translocation of NFkappaB p52, but neither that of NFkappaB p65, nor the phosphorylation of JAK1 and STAT6 was reduced by fucoidan. These results suggest that fucoidan inhibited IgE production by preventing the NFkappaB p52-mediated pathways activated by CD40.

In Vitro Evaluation of Biospecific and Pseudobiospecific Ligands Aimed at Extracorporeal Treatment for Immunoglobulin E Removal

This work investigated the potential use of an alternative adsorbent to anti-immunoglobulin E (IgE)-agarose for IgE selective adsorption therapy. A screening of several commercially available adsorbents (Concanavalin A, Lens culinaris[Lc], d-tryptophan, poly-l-lysine, and aminohexyl immobilized on agarose) was done through batch system assays, considering some criteria, such as adsorption capacity, selectivity, and biocompatibility. In the Lc-agarose adsorbent, total IgE, and specific IgE--for the airborne allergens Dermatophagoides pteronyssinus and Blomia tropicalis--were significantly better removed (63, 58, and 59%, respectively) than immunoglobulin G (19%), immunoglobulin A (33%), immunoglobulin M (9%), and albumin (18%). This adsorbent was packed into a column and the effect of superficial velocity, ratio of plasma volume to bed volume, number of perfusions, and temperature on IgE adsorption were evaluated. In vitro simulation of therapeutic adsorption (single perfusion) indicated that about 50% of total IgE could be eliminated.

Allergy testing: the role of recombinant allergens

Currently, diagnosis of type I allergy is performed using crude allergen extracts, which allow the identification of the allergen-containing source responsible for type I allergic symptoms (e.g., allergic rhino-conjunctivitis, asthma) but not the disease-eliciting molecules. With the introduction of recombinant allergens produced by molecular biology techniques, a large panel of allergenic molecules has become available. The application of these recombinant allergens for in vitro tests has led to new forms of component-resolved diagnosis (CRD) and allows the establishment of a patient's individual reactivity profile. The increasing number of recombinant allergens characterized during the last decade has allowed the development of chip-based allergy tests for simultaneous detection of up to 5000 different allergens and epitopes. The introduction of these recombinant allergen-based tests into clinical practice improves the selection of patients for traditional specific immunotherapy and allows monitoring of the immunological efficacy of specific immunotherapy by measuring allergen-specific IgG antibodies. Besides their diagnostic application, recombinant allergens and hypoallergenic derivatives thereof have also been used as vaccines in clinical trials, and recent results have shown their usefulness for the treatment of type I allergy.

Oral administration of pulverized Konjac glucomannan prevents the increase of plasma immunoglobulin E and immunoglobulin G levels induced by the injection of syngeneic keratinocyte extracts in BALB/c mice

BACKGROUND

Immunoglobulin (Ig) E plays a key role in the pathogenesis of atopic diseases, such as asthma, atopic dermatitis and allergic rhinitis. Oral administration of pulverized Konjac glucomannan (PKGM) has recently been demonstrated to prevent both plasma IgE elevation and developing dermatitis in NC/Nga mice, a model of atopic dermatitis.

OBJECTIVE

To clarify the direct effect of PKGM on the increase of plasma IgE, we employed the system of BALB/c mouse that increases IgE level without developing dermatitis in response to continuous injection of the extract of syngeneic keratinocytes, PAM 212 cells (PAM extract).

METHODS

Three weeks after the start of feeding with either control or PKGM diet, mice were injected subcutaneously with PAM extract bi-weekly for 10 weeks. The levels of plasma Igs were measured by enzyme-linked immunosorbent assay every 2 weeks after the injection. The levels of epsilon germline transcription and the amounts of mRNA for IL-4, IFN-gamma, GATA-3 and T bet gene in the spleen were evaluated by real-time RT-PCR at the end of the experiment.

RESULTS

On the one hand, PKGM prevented the increase of plasma IgE and IgG (IgG1, IgG2b) induced by PAM extract, and on the other hand, it enhanced the levels of plasma IgG3. However, it did not affect the level of plasma IgM. PKGM also reduced the levels of plasma ovalbumin (OVA)-specific IgE in OVA-sensitized mice. Moreover, PKGM attenuated the induction of epsilon germline transcription and expression levels of mRNA for IL-4, IFN-gamma and GATA-3 in the spleen of PAM extract-injected mice. PKGM also attenuated the induction of epsilon germline transcription and mRNA for IFN-gamma and T bet in the spleen of phosphate-buffered saline-injected control mice.

CONCLUSIONS

These results suggested that oral administration of PKGM prevents the elevation of plasma IgE by suppressing IgE class switching in B cells and/or the commitment development of naive lymphocytes to both T-helper type 1 (Th1) and Th2.

Cloning allergens via phage display

Although an impressive list of allergenic structures has been elucidated during the last decade by classical cloning methods, the size of the repertoire of molecular structures able to elicit allergic reactions is still unknown. Selective enrichment of cDNA libraries displayed on phage surface with serum IgE from allergic individuals combined with robotic-based high-throughput screening technology has proved to be extremely successful for the rapid isolation of allergens. The basic concept of linking the phenotype, expressed as gene product displayed on the phage coat, to its genetic information integrated into the phage genome, creates fusion proteins covalently associated with the infectious particle itself. Therefore, cDNA libraries displayed on phage surface can be screened for the presence of specific clones using the discriminative power of affinity purification. The selection of IgE-binding clones involves the enrichment of phage binding to serum IgE immobilised to a solid phase during consecutive rounds of affinity selection. As a consequence of the physical linkage between genotype and phenotype, sequencing of the DNA of the integrated section of the phage genome can readily elucidate the amino acid sequence of the surface-displayed allergen. In spite of some biological limitations imposed by Escherichia coli as expression host, phage surface display technology has strongly contributed to the rapid isolation of a vast variety of IgE-binding structures.

Does my partner cause my allergy?

BACKGROUND

The study of partners can help to understand the impact of environmental influences on the development of allergies. We aimed to test the hypothesis that subjects whose partners have hay fever are at increased risk for the same disease and that the risk increases with the time subjects live together with an affected partner.

METHODS

A nested unmatched case-control study was performed in a random sample of 4261 inhabitants, aged 25-74 years, of the City of Augsburg, Germany, and two adjacent counties. Using standardized computer-assisted face-to-face interviews, we determined the risk of doctor-diagnosed hay fever in subjects who lived together with a partner having the same disease as opposed to subjects living with an unaffected partner. Furthermore, the risk of doctor-diagnosed hay fever depending on the time the subjects had lived together with an affected partner was calculated.

RESULTS

After adjustment for age, sex, parental predisposition and social status, the risk of hay fever was more than double in subjects who lived together with a partner having the same disease (odds ratio, OR(adj.), 2.41; 95% confidence interval, CI, 1.48-3.92). If subjects lived together with an affected partner, the risk of developing the disease increased with the time the partners lived together (1-11 years, OR 1; 12-23 years, OR 1.8; 24-35 years, OR 7.4; 36-54 years, OR 13.7).

CONCLUSION

The risk of developing hay fever is significantly elevated in subjects who live together with a partner having the same disease. The risk further increases with the time the partners live together. This points to important shared environmental influences or behaviours and raises speculations on a transmissible cause.

Strategies for converting allergens into hypoallergenic vaccine candidates

Specific immunotherapy is based on the administration of increasing doses of allergens to allergic patients with the aim of inducing a state of antigen-specific unresponsiveness. Specific immunotherapy is one of the few causative treatment approaches for Type I allergy but may cause numerous side effects, including local inflammatory reactions, systemic manifestations (e.g., asthma attacks) and in the worst case, anaphylactic shock which may lead to death. Several attempts have been made in the past to reduce the rate of side effects. They included the chemical modification of allergen extracts to reduce their allergenic activity and the adsorption of allergen extracts to adjuvants to prevent the systemic release of allergens after administration. During the last decade, cDNAs coding for the most relevant allergens have been isolated and the corresponding allergens have been produced as recombinant molecules. Using allergen-encoding cDNAs, the amino acid sequence of allergens or purified recombinant allergens several strategies can now be applied to produce allergen derivatives with reduced allergenic activity for allergy vaccination in a controlled and reproducible manner. Currently, allergen-encoding cDNAs are used to engineer recombinant hypoallergenic allergen derivatives. According to the amino acid sequences and experimental epitope mapping data, synthetic peptides representing T- or B-cell epitopes are produced and purified recombinant allergens are coupled to novel adjuvants for vaccine formulation. In this article, strategies for the production and evaluation of allergen derivatives with reduced allergenic activity for allergy vaccination are described. These new vaccines hold great promise to improve the current practice of allergen-specific immunotherapy and maybe also used for prophylactic vaccination in the future.

Detailed criteria for the assessment of clinical symptoms in a new murine model of severe allergic conjunctivitis

PURPOSE

The aims of this research were to: (1) generate a rapid protocol for the sensitization of rodents to a defined allergen without footpad injections yet leading to both acute- and late-phase hypersensitivity reactions in the ocular surface; and (2) define detailed criteria for the assessment of clinical symptoms in the acute-phase response.

METHODS

With the approved methods for the use of experimental animals in research and existing sensitization protocols as a starting point, we developed and tested a new protocol with respect to its ability to generate an acute- and late-phase response on ocular challenge. Clinical symptoms were assessed by a trained ophthalmologist under masked conditions, and late-phase responses determined by histologic analysis of conjunctival tissue sections.

RESULTS

A new protocol for the rapid sensitization of mice, avoiding footpad injections, yet yielding both acute- and late-phase allergic responses, was developed. Detailed criteria for the assessment of disease severity were established and tested.

CONCLUSION

This protocol establishes a murine model of allergic conjunctivitis that will be useful for both the study of the molecular and cellular basis of allergic reactions in the ocular surface and the testing of new therapies for this disease.

Blunted cortisol responses to psychosocial stress in asthmatic children: a general feature of atopic disease?

OBJECTIVE

Atopy is defined by the individual predisposition to develop a group of inflammatory disorders in response to certain food or environmental substances that are otherwise innocuous for the host. In previous studies we could demonstrate a reduced responsiveness of the hypothalamus-pituitary-adrenal (HPA) axis to psychosocial stress in young and adult patients with atopic dermatitis (AD), a chronic atopic skin disorder. With respect to the important immunoregulatory role of the HPA axis, especially under stress, this observation could be of clinical relevance and may at least partly explain stress-induced exacerbation of AD. The present study was designed to investigate whether attenuated responsiveness of the HPA axis to stress represents a characteristic feature of AD or whether it can also be found in other chronic manifestations of atopy.

METHODS

Children (aged 7-12) with allergic asthma (AA; N = 17) and age- and sex-matched healthy controls (N = 18) were exposed to the "Trier Social Stress Test for Children"(TSST-C), which mainly consists of a free speech and mental arithmetic tasks in front of an audience. Salivary cortisol was measured in ten-minute intervals before and after the TSST-C, while heart rate was monitored continuously. In addition, early morning cortisol levels (after awakening, +10, +20, +30 minutes) were assessed on three consecutive days.

RESULTS

Data analysis yielded a significant increase of cortisol concentrations (F (9297)= 16.79; p <.001) and heart rates (F(32,992)= 9.16; p <.001) after the stressor with no between-group difference in heart rate responses. However, AA children showed a significantly blunted cortisol response to the TSST-C when compared with the control group (F(9297)= 2.95; p <.01). Awakening in the morning was accompanied by a significant rise of cortisol levels on all three experimental days in AA and control subjects (all p <.001) that was not different between the two groups.

CONCLUSIONS

These findings suggest that a blunted adrenocortical response to stress may represent a common feature of chronic allergic inflammatory processes that may be relevant in different forms of chronic manifestation of atopy.

Identification of the amino acid residues in trichosanthin crucial for IgE response

Trichosanthin (TCS) is the major effective component from Chinese herb Trichosanthes kirilowii. TCS has been approved to be effective in clinical treatment of HIV infection and leukemia, but its allergenicity has limited its clinical usage. To identify amino acid residues in TCS with an important role in IgE induction, TCS-specific IgE mAb (TE1) was used to serve as a probe and TE1 epitope was determined by a random phage-peptide library. Based on phage peptide sequences, TE1 epitope was predicted at amino acid residues 169-174 (QQIGKR) of TCS protein. Based on modeling data, two amino acids (Lys173 and Arg174) on TCS were considered to have a crucial role in binding to TE1. After lysine 173 and arginine 174 were mutated to glycine, the mutant TCS protein specifically lost the binding activity to TE1 mAb and exhibited reduced IgE induction in the immunized mice. The data showed that the IgE epitope of TCS was determined and shown to play a critical role in induction of IgE, and the modification of IgE-epitope may be a useful strategy to reduce the allergenicity of an allergen.

Evolution of IgM, IgE and IgG(1-4 )antibody responses in early childhood monitored with recombinant allergen components: implications for class switch mechanisms

The formation of IgE antibodies against environmental allergens represents the hallmark of type I allergy. Data from in vitro cultured cells and experimental animal models provide controversial evidence for isotype switching from IgM to IgE production via sequential as well as non-sequential (i.e. direct) class switch. We analyzed the evolution of IgE responses in 11 children developing birch pollen and/or grass pollen allergy during the first 7 years of life using purified recombinant allergen molecules (major birch pollen allergen, Bet v 1; major timothy grass pollen allergens, Phl p 1, Phl p 2, Phl p 5). Demographic, clinical and serological data indicated a postnatal sensitization to pollen allergens. A parallel development of IgG(1-4) and IgE responses to recombinant allergen molecules compatible with a strictly sequential class switch to IgE was observed only in one child. The only partly synchronized and dissociated development of allergen-specific antibody responses found in all other cases can be best explained by a partly sequential class switch involving few switch stations or, more likely, by direct class switching. Kinetics and courses of allergen-specific antibody responses (IgM, IgG(1-4), IgE) during the first years of life suggest that, once established, allergen-specific IgE responses are driven by antigen contact rather than by cytokines controlling class switch to IgE.

Yin-Yang 1 activates interleukin-4 gene expression in T cells

Interleukin-4 (IL-4) is a multifunctional cytokine that plays an important role in immune and inflammatory responses. Expression of the IL-4 gene is tightly controlled at the level of gene transcription by both positive and negative regulatory elements in the IL-4 promoter. Several constitutive nuclear factors have been identified that can interact with IL-4 promoter elements in DNA binding assays. Here we report that the zinc-finger protein YY-1 (Yin-Yang 1) can bind to multiple elements within the human IL-4 promoter. Cotransfection of Jurkat T cells with different IL-4 promoter/reporter constructs together with expression vectors encoding antisense, wild-type, or zinc finger-deleted mutant YY-1 suggested that YY-1 enhanced IL-4 promoter activity in a DNA-binding domain-dependent manner. Site-directed mutagenesis revealed that a proximal YY-1-binding site, termed Y0 ((-59)TCATTTT(-53)), was essential for YY-1-driven IL-4 promoter activity. In addition, cotransfected YY-1 enhanced both IL-4 promoter activity and endogenous IL-4 gene expression in nontransformed peripheral blood T cells. Thus, YY-1 positively regulates IL-4 gene expression in lymphocytes.

Proliferation and release of IL-5 and IFN-gamma by peripheral blood mononuclear cells from cat-allergic asthmatics and rhinitics, non-cat-allergic asthmatics, and normal controls to peptides derived from Fel d 1 chain 1

BACKGROUND

In general, T cells from normal, nonatopic individuals respond to aeroallergens with synthesis and release of IFN-gamma. In contrast, release of T(H)2-type cytokines by activated lymphocytes is a feature of allergic rhinitis and atopic asthma.

OBJECTIVE

The purpose of this study was to determine differences in T-cell recognition of epitopes within allergenic sequences, in terms of proliferation and cytokine production, in subjects with atopic asthma compared with subjects with allergic rhinitis and normal controls.

METHODS

Proliferative responses and IL-5/IFN-gamma release patterns from PBMCs from cat-allergic asthmatic, cat-allergic rhinitic, and non-cat-allergic asthmatic subjects and nonatopic normal controls were determined in primary cultures. Cells were challenged with 7 overlapping peptides spanning chain 1 of the major cat allergen, Fel d 1.

RESULTS

The 4 groups did not differ with respect to the ability to mount proliferative responses to Fel d 1 peptides. In all groups, the IFN-gamma responses were predominantly to the amino terminus peptides. Cat-allergic and non-cat-allergic asthmatic subjects (and not cat-allergic rhinitic subjects and normal controls) made IL-5 responses to most of the Fel d 1 peptides, the result being a mixed (T(H)0) cytokine response at the N-terminus and a restricted (T(H)2) response at the C-terminus.

CONCLUSION

Proliferative and IL-5/IFN-gamma responses of T cells from asthmatic and atopic rhinitic subjects and normal controls to allergen peptides can be dissociated. Furthermore, differing cytokine responses to peptides derived from a single antigen suggest that certain domains of the molecule might preferentially induce IL-5 rather than IFN-gamma and as a result could be more important in disease pathogenesis.

High throughput screening: a rapid way to recombinant allergens

Complex allergenic sources such as moulds, foods and mites contain large panels of IgE-binding molecules which need to be cloned, produced and characterized in order to mimic the entire allergenicity of whole extracts reconstituted by mixing single standardized recombinant allergens. Phage display of cDNA libraries allows selective enrichment of allergen-expressing clones using IgE from allergic patients. For the characterization of all different clones present in enriched cDNA libraries in a fast and cost-effective way, however, high-throughput screening technology is required. We have used a high-throughput, quantitative technology for fast identification of all different clones present in selectively enriched phage surface-displayed cDNA libraries in order to characterize whole allergenic repertoires from complex allergenic sources. The strategy, based on a combination of phage display and high-density arrays, allowed fast discovery of panels of related structures from different allergenic sources. They cover secreted, cytoplasmic and structural proteins with or without enzymatic activity and offer a rational explanation for the IgE-mediated cross-reactivity frequently encountered in clinical practice.

Selective inhibition of interleukin-4 gene expression in human T cells by aspirin

Previous studies indicated that aspirin (acetylsalicylic acid [ASA]) can have profound immunomodulatory effects by regulating cytokine gene expression in several types of cells. This study is the first in which concentrations of ASA in the therapeutic range were found to significantly reduce interleukin (IL)-4 secretion and RNA expression in freshly isolated and mitogen-primed human CD4+ T cells. In contrast, ASA did not affect IL-13, interferon-gamma, and IL-2 expression. ASA inhibited IL-4, but not IL-2, promoter-driven chloramphenicol acetyltransferase expression in transiently transfected Jurkat T cells. The structurally unrelated nonsteroidal anti-inflammatory drugs indomethacin and flurbiprofen did not affect cytokine gene expression in T cells, whereas the weak cyclo-oxygenase inhibitor salicylic acid was at least as effective as ASA in inhibiting IL-4 expression and promoter activity. The inhibitory effect of ASA on IL-4 transcription was not mediated by decreased nuclear expression of the known salicylate target nuclear factor (NF)-kappaB and was accompanied by reduced binding of an inducible factor to an IL-4 promoter region upstream of, but not overlapping, the NF of activated T cells- and NF-kappaB-binding P1 element. It is concluded that anti-inflammatory salicylates, by means of a previously unrecognized mechanism of action, can influence the nature of adaptive immune responses by selectively inhibiting the expression of IL-4, a critical effector of these responses, in CD4+ T cells.

Transcriptional activity of the distal CD40 ligand promoter

CD40 ligand (CD40L, CD154) is a T cell cytokine with highly regulated expression that requires the transcription factor nuclear factor of activated T cells (NF-AT) to bind at two sites in the proximal CD40L promoter. We have determined that the distal CD40L promoter (-500 to -1300 bp from start of transcription) conveys superior promoter activity in reporter gene assays. Within the distal promoter, we have identified a third NF-AT binding site, at -761 to -756. Oligonucleotides incorporating each of the three NF-AT sites cross-compete for binding of nuclear extracts from activated T cells and bind NF-ATc2 by antibody supershift. Mutation of the distal NF-AT site reduces activity of the 1300 bp CD40L promoter construct to that of the proximal 500 bp construct, which includes only two NF-AT sites. This suggests that the newly identified NF-AT site is the major mediator of transcriptional activation in the distal CD40L promoter.

Immunological principles of adverse drug reactions: the initiation and propagation of immune responses elicited by drug treatment

Adverse drug reactions account for between 2 to 5% of all hospital admissions and can prevent the administration of an otherwise effective therapeutic agent. Hypersensitivity or immune-mediated reactions, although less common, tend to be proportionately more serious. There is convincing evidence to implicate the immune system in the pathogenesis of hypersensitivity reactions. Our understanding of the way in which the immune system recognises drugs is based on the hapten hypothesis; the onset of hypersensitivity involves drug bioactivation, covalent binding to proteins, followed by uptake, antigen processing and T cell proliferation. Central to this hypothesis is the critical role of drug metabolism, with the balance between metabolic bioactivation and detoxification being one important component of individual susceptibility. The purpose of this review is to classify drug hypersensitivity reactions in terms of their clinical presentation, and also to consider recent advances in our understanding of the chemical, biochemical and, in particular, cellular immunological mechanisms of hypersensitivity. The following topics are reviewed: (i) drug disposition and cellular metabolism; (ii) mechanisms of antigen processing and presentation; (iii) the role of cytokines and co-stimulatory molecules in the induction and maintenance of a polarised immune response; and (iv) the application of the hapten hypothesis, danger hypothesis and serial triggering model to drug hypersensitivity. A greater understanding of the mechanism(s) of hypersensitivity may identify novel therapeutic strategies and help to combat one of the more severe forms of adverse reactions to drugs.

Immunoglobulin E antibodies of atopic individuals exhibit a broad usage of VH-gene families

The term 'atopy' describes the genetically determined tendency to mount immunoglobulin E (IgE) antibody responses against per se harmless antigens (allergens). In this study we investigated the usage of VH families in the formation of IgE antibodies in 10 patients suffering from mucosal and/or skin manifestations of atopy. IgE antibody reactivities to exogenous allergen sources as well as to autoallergens were determined and, by immunoabsorption, it was demonstrated that allergen-specific IgE accounted for most of the total serum IgE levels in these patients. Using primers with specificity for the VH1-6 gene families and a primer specific for the first constant region of human IgE, cDNAs coding for IgE heavy chain fragments were amplified using the reverse transcription-polymerase chain reaction (RT-PCR) from peripheral blood lymphocytes of the 10 atopic individuals. Hybridization of the heavy chain-encoding cDNAs with an IgE-specific internal oligonucleotide probe revealed a broad usage of all VH-gene families in the atopic individuals. The spectrum of VH families used in a given atopic individual was neither associated with the type or severity of clinical symptoms nor with the number of allergens recognized. The fact that allergen-specific IgE antibodies in atopic individuals originate from a broad variety of B cells thus reflects the activation of multiple B-cell clones during allergen sensitization. This finding should be borne in mind if therapeutic strategies for Type I allergy are considered that aim at a clonal elimination of allergen-specific B cells.

The Interleukin-4-Receptor: From Recognition Mechanism to Pharmacological Target Structure

Organic synthesis of hormone derivatives is an established route to yield pharmacologically active agents. Until recently this has only been feasible for small organic compounds, but nowadays it is also possible to produce antagonists for larger protein hormones. In particular, the interleukin-4-receptor was a well-suited target for this approach since it plays a pivotal role in the release and progression of allergic diseases. Accordingly, a strong interest and a high medical need is associated with the development of inhibitors. The structural elucidation of the ligand/receptor complex and an improved understanding of the mechanisms concerning receptor binding and activation allow for the rational design of variants that inhibit interleukin-4. Since it is possible to specifically inhibit the interleukin-4-receptor system in this way, a completely new approach to the development of new drugs against allergy and asthma has been established.

Characterization of P5, a novel NFAT/AP-1 site in the human IL-4 promoter

Interleukin 4 (IL-4) gene expression is controlled at the level of transcription by the complex interactions of multiple factors that bind to a proximal promoter region. Nuclear factor of activated T cells (NFAT) can bind up to five purine-rich sequences in the IL-4 promoter termed the P elements (P0-P4). In this paper, we characterize a novel P element in the upstream region of the human IL-4 promoter that we term P5. P5 shares a core NFAT motif ((-353)GGAAA(-357)) and additional sequence similarity with the other P elements and supported strong interactions between the NFATp DNA-binding domain (DBD) and the AP-1 proteins cFos and cJun in DNA-binding assays. Inducibility of the IL-4 promoter was significantly impaired in a reporter construct in which the P5 element was mutated in the context of the full-length promoter. We conclude that P5 represents a novel IL-4 promoter P element that contributes to IL-4 promoter inducibility.

Characterization of a novel negative regulatory element in the human interleukin 4 promoter

Interleukin 4 (IL-4) is a multifunctional cytokine that plays an important role in hematopoiesis, tumor cell growth, and cellular immune responses. Expression of the IL-4 gene is tightly controlled at the level of gene transcription, and many positive regulatory cis-elements have been identified in the proximal IL-4 promoter region. Relatively little is known about factors that downregulate IL-4 transcription. We performed a detailed deletional analysis of the proximal human IL-4 promoter and studied reporter gene activity in transiently transfected Jurkat T lymphoblasts. In this report, we characterize a novel negative regulatory element (termed P2 NRE) that is adjacent to a binding site for nuclear factor of activated T cells. Mutation of P2 NRE significantly enhanced the activity of a 175 base pair IL-4 promoter construct in transiently transfected Jurkat T lymphoblasts. Using nuclear extracts from Jurkat cells, we identify a candidate factor (termed Rep-1) that binds uniquely to the P2 NRE in DNA-binding assays. Rep-1 is not related to other factors previously shown to interact with the IL-4 promoter, and by UV cross-linking and SDS-PAGE analysis, we found that it migrates with a molecular mass of approximately 150 kDa. Characterizing the molecular mechanisms responsible for downregulating the IL-4 promoter should enhance our understanding of IL-4-gene dysregulation in disease states.

HLA DPB1*0201 allele is negatively associated with immunoglobulin E responsiveness specific for house dust mite allergens in Taiwan

BACKGROUND

House dust mite (HDM) Dermatophagoides pteronyssinus is the most important source of indoor allergens that cause allergic diseases in Taiwan. We prepared purified HDM allergens (Der p 1, Der p 2 and Der p 5) to detect allergen-specific immunoglobulin (Ig) E responsiveness among a large number of test subjects. The robust genetic typing system for HLA class II genes also facilitated the study on association of HLA and allergic response toward HDM.

OBJECTIVE

This study intended to investigate the association between HLA class II alleles and the IgE responsiveness to the major allergens from HDM, D. pteronyssinus.

METHODS

Two hundred and forty-eight subjects were selected for HLA association study. Plasma HDM allergen (Der p 1, Der p 2, Der p 5) -specific IgE and Der p 2-specific IgG antibodies were detected by ELISA, while HLA class II -DRB1, -DQA1, -DQB1, -DPB1 genetic polymorphism was determined by polymerase chain reaction/sequence-specific oligonucleotide probe hybridization (PCR/SSOPH). Statistical comparison of the allelic distribution of each HLA class II genes among the individuals with/without HDM allergen-specific IgE and IgG antibodies were performed.

RESULTS

There was no significant association between HLA DRB1, DQB1, DQA1 alleles and HDM-specific IgE responsiveness noted. Only DRB1*0803 and the linked DQA1*0103 alleles showed positive association with Der p 5-specific IgE responsiveness. However, we found that HLA-DPB1*1301 predisposed subjects to IgE responsiveness to HDM Der p 5. HLA DPB1*0501 was weakly associated with the IgE responsiveness to HDM Der p 1 and Der p 5. There was a strong negative association between the HLA-DPB1*0201 allele with IgE responsiveness to Der p 1 (OR: 0.30, P </= 0.0001, P </= 0.0007, Pc </= 0.010).

CONCLUSION

We clearly observed the association between HLA DPB1 alleles and specific IgE responsiveness to HDM major allergens. The molecular mechanism of HLA-DPB1*0201 involvement in protecting subjects from HDM-specific IgE responsiveness awaits further investigation.

Glucocorticoids inhibit calcium- and calcineurin-dependent activation of the human IL-4 promoter

The mechanism by which glucocorticoids (GC) inhibit IL-4 gene expression is currently unknown. In T lymphocytes, IL-4 gene expression is regulated at the level of transcription by increases in intracellular calcium concentration and by the calcium-activated phosphatase calcineurin. In this paper we report that dexamethasone (Dex) inhibits calcium ionophore-induced activation of the human IL-4 promoter in transiently transfected Jurkat T cells. Inhibition of the promoter by Dex is dependent on expression of the GC receptor (GR), because it does not occur in GR-deficient cells. Dex also represses activation of the promoter induced by cotransfecting cells with a constitutively active mutant of calcineurin. Using a series of deletion constructs, we show that the proximal 95 bp of the IL-4 promoter contain a Dex-sensitive regulatory element. This region contains the P1 sequence, a proximal binding site for NF-AT. A calcium-induced but Dex-inhibited nuclear complex containing NF-AT binds to the P1 element in EMSA. Using immunoprecipitation under nondenaturing conditions, we found that the GRalpha isoform coprecipitates with NF-ATc in nuclear extracts of calcium ionophore- and Dex-treated cells. Taken together, our results show that GC inhibit IL-4 gene expression by interfering with NF-AT-dependent transactivation of the proximal human IL-4 promoter.

Molecular characterization of human IgG monoclonal antibodies specific for the major birch pollen allergen Bet v 1. Anti-allergen IgG can enhance the anaphylactic reaction

We report the molecular characterization of five human monoclonal antibodies, BAB1-5 (BAB1: IgG(1); BAB4: IgG(2); BAB2, 3, 5: IgG(4)), with specificity for the major birch pollen allergen, Bet v 1. BAB1-5 were obtained after immunotherapy and contained a high degree of somatic mutations indicative of an antigen-driven affinity maturation process. While BAB1 inhibited the binding of patients IgE to Bet v 1, BAB2 increased IgE recognition of Bet v 1, and, even as Escherichia coli-expressed Fab, augmented Bet v 1-induced immediate type skin reactions. The demonstration that IgG antibodies can enhance allergen-induced allergic reactions is likely to explain the unpredictability of specific immunotherapy.

Definition of human interleukin-4 receptor alpha chain haplotypes and allelic association with atopy markers

Cumulative evidence indicates that the human interleukin-4 receptor alpha chain gene (IL-4Ralpha, CD124) is highly polymorphic in contrast to other cytokine receptor genes. Our group recently identified the IL-4Ralpha variant R551 as being strongly associated with decreased kidney allograft survival. Due to the key immunoregulatory role of IL-4 and controversial reports on the association of IL-4Ralpha variants with atopy, we present here the development of polymerase chain reaction-primer sets for sequence-specific amplification of all seven hitherto described amino acid polymorphisms, and we investigated 158 blood donors prospectively. By using an Expectation-Maximization algorithm, we calculated the presence of 11 putative human IL-4Ralpha haplotypes and identified 4 putative IL-4Ralpha haplotypes with a cumulative frequency of >90%. None of the polymorphisms showed a significant association with the phenotype atopy. All mutant alleles showed a trend toward decreased total IgE levels. This association was only significant (p < 0.05; Mann-Whitney U-test) for the A375, R406, and P478 variants in non-atopic blood-donors (n = 90), presumably due to the high variance of IgE levels among the smaller group of atopic individuals. We postulate that IL-4Ralpha mutations are associated to different extents with a decrease in function of the receptor but do not present a major atopy locus.

Component-resolved diagnosis (CRD) of type I allergy with recombinant grass and tree pollen allergens by skin testing

The diagnosis of Type I allergy is based on the measurement of allergen-specific IgE antibodies and on provocation with allergens, most frequently conducted by skin testing. Both forms of diagnosis are currently performed with allergen extracts that are difficult to standardize regarding their allergen contents, and which contain additional undefined nonallergenic components. We report the expression in Escherichia coli and purification of some of the most relevant timothy grass- and birch pollen allergens. Recombinant timothy grass- (rPhl p 1, rPhl p 2, rPhl p 5) and birch pollen (rBet v 1, rBet v 2) allergens were purified and used for the measurement of allergen-specific IgE and IgG subclass responses as well as for skin prick testing in 55 pollen allergic patients and 10 nonatopic individuals. Results obtained showed that the recombinant allergens allowed in vivo allergy diagnosis in 52 of 54 of the grass pollen and in 35 of 36 of the birch pollen allergic patients. Positive skin reactions were observed almost exclusively in patients containing detectable allergen-specific IgE antibodies but not in the nonatopic group; however, sensitivity to a given allergen as measured by skin reactivity was weakly correlated with the levels of allergen-specific IgE. Our results demonstrate that recombinant allergens can be used for component-resolved skin test diagnosis (CRD) of the patients' allergen sensitization profile, whereas allergen extracts at best allow to identify allergen-containing sources. CRD may thus represent the basis for novel forms of patient-tailored immunotherapy.

Suppressive versus stimulatory effects of allergen/cholera toxoid (CTB) conjugates depending on the nature of the allergen in a murine model of type I allergy

Recent reports have demonstrated that feeding small amounts of antigen conjugated to the B subunit of cholera toxin (CTB) suppress immune responses in experimental models of certain T(h)1-based autoimmune diseases. We have established a model of aerosol sensitization leading to T(h)2-mediated allergic immune responses in BALB/c mice. In the present study two different antigens, the dietary antigen ovalbumin (OVA) and the inhalant allergen Bet v 1 (the major birch pollen allergen), chemically coupled to recombinant CTB were tested for their potential to influence T(h)2-like immune responses. Intranasal administration of OVA-CTB prior to sensitization with OVA led to a significant decrease of antigen-specific IgE antibody levels, but a marked increase of OVA-specific IgG2a antibodies as compared to non-pretreated, sensitized animals. Antigen-specific lympho-proliferative responses in vitro were reduced by 65% in the pretreated group; IL-5 and IL-4 production were decreased in responder cells of lungs and spleens of nasally pretreated mice. In contrast, mucosal administration of rBet v 1-CTB conjugates prior to sensitization led to an up-regulation of allergen-specific IgE, IgG1 and IgG2a, increased in vitro lympho-proliferative responses as well as augmented production of IL-5, IL-4, IL-10 and IFN-gamma. Intranasal administration prior to sensitization of unconjugated allergens showed also contrasting effects: OVA could not significantly influence antigen-specific antibody or cytokine production, whereas intranasal pretreatment with unconjugated Bet v 1 suppressed allergen-specific immune responses in vivo and in vitro. These results demonstrated that the two antigens-in conjugated as in unconjugated form-had different effects on the T(h)2 immune responses. We therefore conclude that the tolerogenic or immunogenic properties of CTB-and probably also other antigen-delivery systems-strongly depend on the nature of the coupled antigen-allergen.

B cell epitopes of the major timothy grass pollen allergen, phl p 1, revealed by gene fragmentation as candidates for immunotherapy

Group 1 grass pollen allergens are recognized by IgE antibodies of almost 40% of allergic individuals and therefore belong to the most important elicitors of Type I allergy worldwide. We have previously isolated the cDNA coding for the group 1 allergen from timothy grass, Phl p 1, and demonstrated that recombinant Phl p 1 contains most of the B cell as well as T cell epitopes of group 1 allergens from a variety of grass and corn species. Here we determine continuous B cell epitopes of Phl p 1 by gene fragmentation. IgE antibodies of grass pollen allergic patients identified five continuous epitope-containing areas that on an average bound 40% of Phl p 1-specific IgE antibodies and were stably recognized in the course of disease. In contrast to untreated patients, patients undergoing grass pollen immunotherapy started to mount IgG(4) antibodies to the recombinant IgE-defined fragments in the course of immunotherapy. The protective role of these IgG(4) antibodies is demonstrated by observations that 1) increases in rPhl p 1 fragment-specific IgG(4) were in parallel with decreases in Phl p 1-specific IgE, and 2) preincubation of rPhl p 1 with patients sera containing rPhl p 1 fragment-specific IgG(4) blocked histamine release from basophils of an untreated grass pollen allergic patient. We propose to use recombinant Phl p 1 fragments for active immunotherapy in order to induce protective IgG responses against IgE epitopes in grass pollen allergic patients. This concept may be applied for the development of allergy vaccines whenever the primary sequence or structure of an allergen is available.

Suppressive versus stimulatory effects of allergen/cholera toxoid (CTB) conjugates depending on the nature of the allergen in a murine model of type I allergy

Recent reports have demonstrated that feeding small amounts of antigen conjugated to the B subunit of cholera toxin (CTB) suppress immune responses in experimental models of certain Th1-based autoimmune diseases. We have established a model of aerosol sensitization leading to Th2-mediated allergic immune responses in BALB/c mice. In the present study two different antigens, the dietary antigen ovalbumin (OVA) and the inhalant allergen Bet v 1 (the major birch pollen allergen), chemically coupled to recombinant CTB were tested for their potential to influence Th2-like immune responses. Intranasal administration of OVA-CTB prior to sensitization with OVA led to a significant decrease of antigen-specific IgE antibody levels, but a marked increase of OVA-specific IgG2a antibodies as compared to non-pretreated, sensitized animals. Antigen-specific lympho-proliferative responses in vitro were reduced by 65% in the pretreated group; IL-5 and IL-4, but not IFN-gamma, production were markedly decreased in responder cells of lungs and spleens of nasally pretreated mice. In contrast, mucosal administration of rBet v 1-CTB conjugates prior to sensitization led to an up-regulation of allergen-specific IgE, IgG1 and IgG2a, increased in vitro lympho-proliferative responses as well as augmented production of IL-5, IL-4, IL-10 and IFN-gamma. Intranasal administration prior to sensitization of unconjugated allergens showed also contrasting effects: OVA could not significantly influence antigen-specific antibody or cytokine production, whereas intranasal pretreatment with unconjugated Bet v 1 suppressed allergen-specific immune responses in vivo and in vitro. These results demonstrated that the two antigens--in conjugated as in unconjugated form--had different effects on the Th2 immune responses. We therefore conclude that the tolerogenic or immunogenic properties of CTB--and probably also other antigen-delivery systems--strongly depend on the nature of the coupled antigen-allergen.

Are atopic individuals genetically predisposed to produce a specific protease profile in antigen processing?

Genetic factors play a major role in the development of allergic diseases such as asthma and atopic dermatitis. Since allergic response involves immune processes such as antigen-processing and -presentation, it is conceivable that the genes involved in the regulation of these processes may be crucial in determining an individual's susceptibility to allergic diseases. In this paper, it is proposed that proteases, used in antigen-processing, are involved in the genetic predisposition to allergic diseases.

Induction of antibody responses to new B cell epitopes indicates vaccination character of allergen immunotherapy

Whether the modulation of antibody responses can contribute to the improvement of clinical symptoms in patients receiving allergen immunotherapy represents a controversial issue. We have used purified [seven recombinant (r) and one natural] timothy grass pollen allergens as well as recombinant B cell epitope-containing fragments of the major timothy grass pollen allergen, Phl p 1, to investigate humoral immune responses in eight allergic patients receiving grass pollen-specific immunotherapy. We found that the administration of aluminium hydroxide-adsorbed grass pollen extract induced complex changes in allergen/epitope-specific antibody responses: increases in IgG subclass (IgG1, IgG2, IgG4) responses against allergens recognized before the therapy were observed. All eight patients started to mount IgE and IgG4 responses to continuous Phl p 1 epitopes not recognized before the therapy and a de novo induction of IgE antibodies against new allergens was found in one patient. Evidence for a protective role of IgG antibodies specific for continuous Phl p 1 epitopes was provided by the demonstration that preincubation of rPhl p 1 with human serum containing therapy-induced Phl p 1-specific IgG inhibited rPhl p 1-induced histamine release from basophils of a grass pollen-allergic patient. Our finding that immunotherapy induced antibody responses against previously not recognized B cell epitopes indicates the vaccination character of this treatment. The fact that patients started to mount de novo IgE as well as protective IgG responses against epitopes may explain the unpredictability of specific immunotherapy performed with allergen extracts and emphasizes the need for novel forms of component-resolved immunotherapy.

Calcium-dependent immunoglobulin E recognition of the apo- and calcium-bound form of a cross-reactive two EF-hand timothy grass pollen allergen, Phl p 7

Type I allergy, an immunodisorder that affects almost 20% of the population worldwide, is based on the immunoglobulin E (IgE) recognition of per se innocuous antigens (allergens). Pollen from wind-pollinated plants belong to the most potent allergen sources. We report the isolation of a cDNA coding for a 8.6 kDa two EF-hand calcium binding allergen, Phl p 7, from a timothy grass (Phleum pratense) pollen expression cDNA library, using serum IgE from a grass pollen allergic patient. Sequence analysis identified Phl p 7 as a member of a recently discovered subfamily of pollen-specific calcium binding proteins. Recombinant Phl p 7 was expressed in Escherichia coli and purified to homogeneity as determined by mass spectroscopy. Approximately 10% of pollen allergic patients displayed IgE reactivity to rPhl p 7 and Phl p 7-homologous allergens present in pollens of monocotyledonic and dicotyledonic plants. Circular dichroism analysis of the calcium-bound and apo-rPhl p 7 indicated that differences in IgE recognition may be due to calcium-induced changes in the protein conformation. The fact that patients mount IgE antibodies against different protein conformations is interpreted as a footprint of a preferential sensitization against either form. The biological activity of rPhl p 7 was demonstrated by its ability to induce basophil histamine release and immediate type skin reactions in sensitized individuals. In conclusion, IgE binding to Phl p 7 represents an example for the conformation-dependent IgE recognition of an allergen. Recombinant Phl p 7 may be used for diagnosis and perhaps treatment of a group of patients who suffer from allergy to pollens of many unrelated plant species.

Th1 and Th2 cytokine mRNA profiles in childhood nephrotic syndrome: evidence for increased IL-13 mRNA expression in relapse

Idiopathic nephrotic syndrome of childhood is thought to be associated with T lymphocyte dysfunction often triggered by viral infections, with the production of circulating factor(s) resulting in proteinuria. In view of the conflicting evidence of T cell activation and Th1 or Th2 pattern of cytokine synthesis in this disease, this study examined the mRNA expression of interleukin-2 (IL-2), interferon-gamma, IL-4, and IL-13 from CD4+ and CD8+ T cells in steroid-responsive nephrotic patients in relapse and remission. Fifty-five children with steroid-responsive nephrotic syndrome were included in this study, together with 34 normal controls and 24 patient controls with viral infections. RNA was isolated from purified CD4+ or CD8+ cells from peripheral blood and subjected to reverse transcription-PCR. Cytokine mRNA expression was measured semiquantitatively, and a cytokine index was derived from densitometric readings, with cyclophilin as the housekeeping gene. Both cross-sectional and paired data showed an increased CD4+ and CD8+ IL-13 mRNA expression in patients with nephrotic relapse as compared to remission, normal, and patient controls (P < 0.008). This was also associated with increased cytoplasmic IL-13 expression in phorbol myristate acetate/ionomycin-activated CD3+ cells (6.66+/-3.39%) from patients with nephrotic relapse compared to remission (2.59+/-1.35%) (P < 0.0001). However, there was no significant difference in CD4+ or CD8+ IL-2, interferon-gamma and IL-4 mRNA expression. IL-13 is an important T cell cytokine with anti-inflammatory and immunomodulatory functions on B cells and monocytes. It is conceivable that IL-13 may act on monocytes to produce vascular permeability factor(s) involved in the pathogenesis of proteinuria in patients with relapse nephrotic syndrome.

Stat6 Inhibits Human Interleukin-4 Promoter Activity in T Cells

The differentiation of naive T-helper (Th) cells into cytokine-secreting effector Th cells requires exposure to multiple signals, including exogenous cytokines. Interleukin-4 (IL-4) plays a major role in this process by promoting the differentiation of IL-4–secreting Th2 cells. In Th2 cells, IL-4 gene expression is tightly controlled at the level of transcription by the coordinated binding of multiple transcription factors to regulatory elements in the proximal promoter region. Nuclear factor of activated T cell (NFAT) family members play a critical role in regulating IL-4 transcription and interact with up to five sequences (termed P0 through P4) in the IL-4 promoter. The molecular mechanisms by which IL-4 induces expression of the IL-4 gene are not known, although the IL-4–activated transcription factor signal transducer and activator of transcription 6 (Stat6) is required for this effect. We report here that Stat6 interacts with three binding sites in the human IL-4 promoter by electrophoretic mobility shift assays. These sites overlap the P1, P2, and P4 NFAT elements. To investigate the role of Stat6 in regulating IL-4 transcription, we used Stat6-deficient Jurkat T cells with different intact IL-4 promoter constructs in cotransfection assays. We show that, whereas a multimerized response element from the germline IgE promoter was highly induced by IL-4 in Stat6-expressing Jurkat cells, the intact human IL-4 promoter was repressed under similar conditions. We conclude that the function of Stat6 is highly dependent on promoter context and that this factor promotes IL-4 gene expression in an indirect manner.