Search PubMed⌕ Search

Biomedical subjects

Kerstin Westritschnig

Publications and source records attributed to Kerstin Westritschnig.

9 recordsLinked to original sources
PubMed2006

Allergen cleavage by effector cell-derived proteases regulates allergic inflammation.

The key event of allergic inflammation, allergen-induced crosslinking of mast cell-bound IgE antibodies, is accompanied by release of inflammatory mediators, cytokines, and proteases, in particular beta-tryptase. We provide evidence that protease-mediated cleavage of allergens represents a mechanism that regulates allergen-induced mast cell activation. When used in molar ratios as they occur in vivo, purified beta-tryptase cleaved major grass and birch pollen allergens, resulting in defined peptide fragments as mapped by mass spectrometry. Tryptase-cleaved allergens showed reduced IgE reactivity and allergenic activity. The biological relevance is demonstrated by the fact that lysates from activated human mast cells containing tryptase levels as they occur in vivo cleaved allergens. Additionally, protamine, an inhibitor of heparin-dependent effector cell proteases, augmented allergen-induced release of mediators from effector cells. Protease-mediated allergen cleavage may represent an important mechanism for terminating allergen-induced effector cell activation.

Allergens↗
PubMed2004

Generation of an allergy vaccine by disruption of the three-dimensional structure of the cross-reactive calcium-binding allergen, Phl p 7.

The grass pollen allergen, Phl p 7, belongs to a family of highly cross-reactive calcium-binding pollen allergens. Because Phl p 7 contains most of the disease-eliciting epitopes of pollen-derived calcium-binding allergens, hypoallergenic variants were engineered according to the x-ray crystal structure of Phl p 7 for allergy vaccination. In three recombinant variants, amino acids essential for calcium binding were mutated, and two peptides comprising the N- and C-terminal half were obtained by synthetic peptide chemistry. As determined by circular dichroism analysis and size exclusion chromatography coupled to mass spectrometry, recombinant mutants showed altered structural fold and lacked calcium-binding capacity, whereas the two synthetic peptides had completely lost their structural fold. Allergic patients' IgE Ab binding was strongest reduced to the variant containing two mutations in each of the two calcium-binding sites and to the peptides. Basophil histamine release and skin test experiments in allergic patients identified the peptides as the vaccine candidates with lowest allergenic activity. Immunization of rabbits with the peptides induced IgG Abs that blocked allergic patients' IgE binding to Phl p 7 and inhibited allergen-induced basophil degranulation. Our results indicate that disruption of an allergen's three-dimensional structure represents a general strategy for the generation of hypoallergenic allergy vaccines, and demonstrate the importance of allergen-specific IgG Abs for the inhibition of immediate allergic symptoms.

Allergens↗
PubMed2003

Identification of cross-reactive and genuine Parietaria judaica pollen allergens.

BACKGROUND: The weed Parietaria judaica is one of the most important pollen allergen sources in the Mediterranean area. OBJECTIVE: We sought to identify P judaica pollen allergen, which might be used to serologically distinguish genuine Parietaria sensitization and cross-reactivity to allergens from other weed species (eg, mugwort and ragweed). METHODS: The allergen profile of P judaica IgE-reactive sera from weed pollen-sensitized allergic individuals from the Mediterranean region (n = 36) with high Parietaria pollen exposure and from weed pollen-allergic patients with little or no Parietaria exposure (Austria, n = 42; Scandinavia, n = 8; United States, n = 19) was established by CAP FEIA measurements and by IgE immunoblot inhibition experiments with recombinant allergens. RESULTS: The majority (83%) of the Mediterranean weed pollen-allergic patients mounted high IgE antibody levels (mean specific IgE, 20.89 kUA/L) against recombinant (r) Par j 2, whereas only 7% of the non-Mediterranean weed-allergic patients showed low IgE reactivity to rPar j 2 (mean specific IgE, 1.03 kUA/L). The cytoskeletal protein profilin and a 2-EF-hand calcium-binding allergen were identified as cross-reactive Parietaria allergens, which were recognized preferentially by Parietaria -positive, non-Mediterranean weed pollen-allergic patients. CONCLUSION: rPar j 2 might be used as a diagnostic marker allergen to identify weed pollen-allergic patients who are genuinely sensitized against Parietaria pollen and thus would be particularly suited for specific immunotherapy with Parietaria pollen extract.

Allergens↗
PubMed2003

Can we genetically engineer safer and more effective immunotherapy reagents?

PURPOSE OF REVIEW: Progress in allergen-specific immunotherapy, the only causative form of allergy treatment, was limited by the lack of defined allergen molecules for vaccine formulation. Today the genetic informations for the most common allergens have been obtained. Here we review recombinant allergen-based technologies for the improvement of diagnosis and therapy of allergy. RECENT FINDINGS: Numerous strategies, including the genetic engineering of allergens for reduction of allergenic activity, have been developed to improve allergen-specific immunotherapy. Genetically modified allergen derivatives with reduced allergenic activity, preserved T cell epitope repertoire and retained immunogenicity have been characterized in vitro and in vivo. SUMMARY: Based on the review of the recently published data we argue that it is possible to genetically engineer safer and more effective immunotherapy reagents.

Antigens↗
PubMed2002

The cross-reactive calcium-binding pollen allergen, Phl p 7, reveals a novel dimer assembly.

The timothy grass pollen allergen Phl p 7 assembles most of the IgE epitopes of a novel family of 2 EF-hand calcium-binding proteins and therefore represents a diagnostic marker allergen and vaccine candidate for immunotherapy. Here we report the first three-dimensional structure of a representative of the 2 EF-hand allergen family, Phl p 7, in the calcium-bound form. The protein occurs as a novel dimer assembly with unique features: in contrast to well known EF-hand proteins such as calmodulin, parvalbumin or the S100 proteins, Phl p 7 adopts an extended conformation. Two protein monomers assemble in a head-to-tail arrangement with domain-swapped EF-hand pairing. The intertwined dimer adopts a barrel-like structure with an extended hydrophobic cavity providing a ligand-binding site. Calcium binding acts as a conformational switch between an open and a closed dimeric form of Phl p 7. These findings are interesting in the context of lipid- and calcium-dependent pollen tube growth. Furthermore, the structure of Phl p 7 allows for the rational development of vaccine strategies for treatment of sensitized allergic patients.

Allergens↗
PubMed2002

Molecular, structural, and immunologic relationships between different families of recombinant calcium-binding pollen allergens.

BACKGROUND: Calcium-binding plant allergens can be grouped in different families according to the number of calcium-binding domains (EF hands). OBJECTIVE: We sought to identify pollens containing crossreactive calcium-binding allergens and to investigate structural and immunologic similarities of members belonging to different families of calcium-binding allergens. METHODS: By means of multiple sequence alignment and molecular modeling, we searched for structural similarities among pollen allergens with 2 (Phl p 7, timothy grass; Aln g 4, alder), 3 (Bet v 3, birch) and 4 EF hands (Jun o 4, prickly juniper). Purified recombinant Aln g 4 and Jun o 4 were used to determine the prevalence of IgE recognition in 210 patients sensitized to different pollens and to search, by means of ELISA competition, for the presence of cross-reactive epitopes in pollens from 16 unrelated plant species. IgE cross-reactivity among the allergen families was studied with purified rPhl p 7, rAln g 4, rBet v 3, and rJun o 4 and 2 synthetic peptides comprising the N-terminal and C-terminal EF hands of Phl p 7 by means of ELISA competition. RESULTS: Structural similarities were found by using molecular modeling among the allergens with 2, 3, and 4 EF hands. Pollens from 16 unrelated plants contained Aln g 4- and Jun o 4-related epitopes. Twenty-two percent of the patients with multiple pollen sensitization reacted to at least one of the calcium-binding allergens. A hierarchy of IgE cross-reactivity (rPhl p7 > rAln g 4 > rJun o 4 > rBet v 3) could be established that identified rPhl p 7 as the EF-hand allergen containing most IgE epitopes in the population studied. CONCLUSION: The demonstration that members of different families of calcium-binding plant allergens share similarities suggests that it may be possible to use representative molecules for the diagnosis and therapy of allergies to EF-hand allergens.

Allergens↗
PubMed2002

Different IgE reactivity profiles in birch pollen-sensitive patients from six European populations revealed by recombinant allergens: an imprint of local sensitization.

BACKGROUND: Sensitivity to birch pollen allergens is a common feature among European patients with seasonal pollen allergy. In this in vitro study, we examined the specific serum IgE binding profiles to individual birch pollen allergens in birch-sensitive patients from six European populations. METHODS: The study included 242 patients from Finland, Sweden, Austria, France, Switzerland and Italy. All suffered from seasonal rhinoconjunctivitis and/or asthma. Their sera were analyzed for specific IgE reactivity to individual birch pollen allergens (recombinant Bet v 1, Bet v 2 and Bet v 4) and natural birch pollen extract using Pharmacia CAP System and immunoblotting. RESULTS: Almost all Finnish, Swedish and Austrian sera contained IgE specific for Bet v 1 (>or=98%). Bet v 1-specific IgE antibodies were found in 90% of the French sera, and in 65 and 62% of the sera from Switzerland and Italy, respectively. Few Finnish (2%) and Swedish (12%) patients had IgE to Bet v 2, while Bet v 2 reactivity was more common in the other populations (20-43%). Reactivity to Bet v 4 was rare in all populations (5-11%) except for the Italian patients, in whom 3 of 11 sera were positive (27%). The immunoblot results supported the specific IgE profiles obtained with Pharmacia CAP System showing a broader IgE reactivity profile in patients from central and southern Europe as compared to northern Europe. CONCLUSION: Component-resolved allergy diagnosis with recombinant allergens reveals that the IgE reactivity profiles to individual birch pollen allergens vary between European populations. This observation may be explained by sensitization to different allergen sources and will have an impact on allergen-specific prevention and therapy strategies.

Adolescent↗