The present invention relates to a method for reducing allergenic activity of wild-type protein allergens, novel allergen derivatives and allergy vaccination strategies.
Allergy is the inherited or acquired specific alternation of the reaction capability against foreign (i.e. non-self) substances which are normally harmless (“allergens”). Allergy is connected with inflammatory reactions in the affected organ systems (skin, conjunctiva, nose, pharynx, bronchial mucosa, gastrointestinal tract), immediate disease symptoms, such as allergic rhinitis, conjunctivitis, dermatitis, anaphylactic shock and asthma, and chronic disease manifestations, such as late stage reactions in asthma and atopic dermatitis.
Type I allergy represents a genetically determined hypersensitivity disease which affects about 20% of the industrialised world population. The pathophysiological hallmark of Type I allergy is the production of immunoglobulin E (IgE) antibodies against otherwise harmless antigens (allergens).
Currently, the only causative form of allergy treatment is an allergen-specific immunotherapy wherein increasing allergen doses are administered to the patient in order to induce allergen-specific unresponsiveness. While several studies have shown clinical effectiveness of allergen-specific immunotherapy, the underlying mechanisms are not fully understood.
The major disadvantage of allergen-specific immunotherapy is the dependency on the use of natural allergen extracts which are difficult, if not impossible to standardise, at least to an industrial production level. Such natural allergen extracts consist of different allergenic and non allergenic compounds and due to this fact it is possible that certain allergens are not present in the administered extract or—even worse—that patients can develop new IgE-specificities to components in the course of the treatment. Another disadvantage of extract-based therapy results from the fact that the administration of biologically active allergen preparations can induce anaphylactic side effects.
The application of molecular biology techniques in the field of allergen characterisation has allowed to isolate the cDNAs coding for all relevant environmental allergens and allowed the production of recombinant allergens. Using such recombinant allergens has made it possible to determine the individual patient's reactivity profile either by in vitro diagnostic methods (i.e. detection of allergen-specific IgE antibodies in serum) or by in vivo testing. Based on this technology, the possibility to develop novel component-based vaccination strategies against allergy, especially against Type I allergy, which are tailored to the patient's sensitisation profile appeared to be possible. However, due to the similarity of the recombinant allergens to their natural counterparts, also recombinant allergens exhibit significant allergenic activity. Since the recombinant allergens closely mimic the allergenic activity of the wild-type allergens, all the drawbacks connected with this allergenic activity in immunotherapy applying natural allergens are also present for recombinant allergens. In order to improve immunotherapy the allergenic activity of the recombinant allergens has to be reduced so that the dose of the administered allergens can be increased with only a low risk of anaphylactic side effects.
It has been suggested to influence exclusively the activity of allergen-specific T cells by administration of peptides containing T cell epitopes only. T cell epitopes represent small peptides which result from the proteolytic digestion of intact allergens by antigen representing cells. Such T cell epitopes can be produced as synthetic peptides. Tests conducted so far with T cell epitopes, however, only showed poor results and low efficacy. Several explanations for the low efficacy of T cell peptide-based immunotherapy have been considered: first, it may be difficult to administer the optimal dose to achieve T cell tolerance instead of activation. Second, small T cell epitope peptides will have a short half-life in the body. Third, there is considerable evidence that IgE production in atopic individuals represents a memory immune response which does not require de novo class switching and thus cannot be controlled by T cell-derived cytokines. Therapy forms which are based exclusively on the administration of T cell epitopes may therefore modulate the activity of allergen-specific T cells but may have little influence on the production of allergen-specific IgE antibodies by already switched memory B cells.
It has further been suggested to produce hypoallergenic allergen derivates or fragments by recombinant DNA technology or peptide synthesis. Such derivatives or fragments bear T cell epitopes and can induce IgG antibodies that compete with IgE recognition of the native allergen. It was demonstrated more than 20 years ago that proteolytic digestion of allergens yielded small allergen fragments which in part retained their IgE binding capacity but failed to elicit immediate type reactions. While proteolysis of allergens is difficult to control and standardise, molecular biology has opened up new avenues for the production of IgE binding haptens. Such IgE binding haptens have been suggested to be useful for active immunisation with reduced risks of anaphylactic effects and for passive therapy to saturate effector cell-bound IgE prior to allergen contact and thus block allergen-induced mediator release.
Another suggestion was to produce hypoallergenic allergen versions by genetic engineering based on the observation that allergens can naturally occur as isoforms with differ in only a few amino acid residues and/or in conformations with low IgE binding capacity. For example, oligomerisation of the major birch pollen allergen, Bet v 1, by genetic engineering yielded a recombinant trimer with greatly reduced allergenic activity. Alternatively, introduction of point mutations has been suggested to either lead to conformational changes in the allergen structure and thus disrupt discontinuous IgE epitopes or directly affect the IgE binding capacity (Valenta et al., Biol. Chem. 380 (1999), 815-824).
It has also been shown that fragmentation of the allergen into few parts (e.g. into two parts) leads to an almost complete loss of IgE binding capacity and allergenic activity of the allergen due to a loss of their native-like folds (Vrtala et al. (J. Clin. Invest. 99 (1997), 1673-1681) for Bet v 1, Twardosz et al. (BBRC 239 (1997), 197-204) for Bet v 4, Hayek et al. (J. Immunol. 161 (1998), 7031-7039) for Aln g 4, Zeiler et al. (J. Allergy Clin. Immunol. 100 (1997), 721-727) for bovine dander allergen, Elfman (Int. Arch. Allergy Immunol. 117 (1998), 167-173) for Lep d2), Westritschnig (J. Immunol. 172 (2004), 5684-5692) for Phlp 7), . . . ). Fragmentation of proteins containing primarily discontinuous/conformational IgE epitopes leads to a substantial reduction of the allergen's IgE binding capacity. Based on this knowledge, it was investigated in the prior art whether such hypoallergenic allergen fragments can induce protective immune responses in vivo (Westritschnig et al. (Curr. Opinion in Allergy and Clin. Immunol. 3 (2003), 495-500)).
It is an object of the present invention to provide means and methods for improved allergy immunotherapy based on the above mentioned knowledge. Such methods and means should be effective, connected with a low risk for anaphylactic shock, easily applicable and adapted to the needs of an individual patient and easily transformable into industrial scales.
Therefore the present invention provides a method for producing derivatives of wild-type protein allergens with reduced allergenic activity, which is characterized in by the following steps:
The present method is based on the fact that fragmentation of proteins containing primarily discontinuous/conformational IgE epitopes leads to a substantial reduction of the allergen's IgE binding capacity. However, fragments of certain allergens were too less immunogenic to induce a protective antibody response (Westritschnig et al., (2004)).
With the present method, new and defined protein allergen derivatives are provided which combine the advantages of the T cell and B cell epitope-based approaches. At the same time, the disadvantages of vaccination with fragments only or sophisticated arrangements of fragments (such as IgE binding haptens and shuffling with three or more fragments) are not present for the allergen derivatives of the present invention.
In fact it could be shown with the present invention that the optimal results can be obtained with the structure which—with respect to completeness of structure elements—most closely resembles the wild-type allergen (i.e. with all amino acids of the wild-type allergen), however, without its allergenic activity (or with a sufficiently reduced allergenic activity). Of course, if only a few amino acid residues are lost (deleted) or added (inserted) in the course of generation of the allergen derivatives or if the parts are combined by a linker instead of a direct combination, the advantages according to the present invention are still present. This reduction or abolishment of allergenic activity is achieved by the known and general principle of dividing the allergen into defined fragments. In addition to this general principle, the present invention rejoins the two parts of the allergen obtained in inverse orientation which leads to allergen derivatives which contain essentially all relevant structural information of the allergen (because the amino acid sequence is contained in full or almost in full in the allergen derivates according to the present invention) but with only low (or no) remaining allergenic activity compared to the wild-type allergen.
These “head-to tail” derivatives according to the present invention enable a suitable, individual and efficient immunotherapy for allergy patients which is easily up-scaleable with routine steps. The derivates according to the present invention induce protective IgG antibodies which can block patient's IgE binding to wild-type allergens and inhibit allergen-induced basophil degranulation.
The present method is specifically suitable for recombinant DNA technology. Once the derivative is constructed by genetic engineering, it can easily be obtained in considerable amounts by transgene expression on an industrial scale in suitable hosts. The allergen derivatives according to the present invention can preferably be produced in a host with high expression capacity.
Preferred allergens to be modified by the present invention include all major protein allergens available e.g. under www.allergen.org/List.htm. Specifically preferred groups of allergens according to the present invention include profilins, especially Phl p 12, birch allergens, especially Bet v 4, dust mite allergens, especially Der p2, storage mite allergens, especially Lep d 2, timothy grass allergens, especially Phl p 7, and the allergens listed in table A.
Ambrosia artemisiifolia
Ambrosia trifida
Artemisia vulgaris
Helianthus annuus
Mercurialis annua
Chenopodium album
Salsola kali
Humulus japonicus
Parietaria judaica
Parietaria officinalis
Cynodon dactylon
Dactylis glomerata
Festuca pratensis
Holcus lanatus
Lolium perenne
Phalaris aquatica
Phleum pratense
Poa pratensis
Sorghum halepense
Phoenix dactylifera
Alnus glutinosa
Betula verrucosa
Carpinus betulus
Castanea sativa
Corylus avellana
Quercus alba
Fraxinus excelsior
Ligustrum vulgare
Olea europea
Syringa vulgaris
Plantago lanceolata
Cryptomeria japonica
Cupressus arizonica
Cupressus sempervirens
Juniperus ashei
Juniperus oxycedrus
Juniperus sabinoides
Juniperus virginiana
Platanus acerifolia
Acarus siro
Blomia tropicalis
Dermatophagoides farinae
Dermatophagoides microceras
Dermatophagoides pteronyssinus
Euroglyphus maynei
Glycyphagus domesticus
Lepidoglyphus destructor
Tyrophagus putrescentiae
Bos domesticus
Canis familiaris
Equus caballus
Felis domesticus
Cavia porcellus
Mus musculus
Rattus norvegius
Alternaria alternata
Cladosporium herbarum
Aspergillus flavus
Aspergillus fumigatus
Aspergillus niger
Aspergillus oryzae
Penicillium brevicompactum
Penicillium chrysogenum
Penicillium citrinum
Penicillium oxalicum
Fusarium culmorum
Trichophyton rubrum
Trichophyton tonsurans
Candida albicans
Candida boidinii
Psilocybe cubensis
Coprinus comatus
Rhodotorula mucilaginosa
Malassezia furfur
Malassezia sympodialis
Epicoccum purpurascens
Aedes aegyptii
Apis mellifera
Bombus pennsylvanicus
Blattella germanica
Periplaneta americana
Chironomus kiiensis
Chironomus thummi thummi
Ctenocephalides felis felis
Thaumetopoea pityocampa
Lepisma saccharina
Dolichovespula maculate
Dolichovespula arenaria
Polistes annularies
Polistes dominulus
Polistes exclamans
Polistes fuscatus
Polistes gallicus
Polistes metricus
Vespa crabo
Vespa mandarina
Vespula flavopilosa
Vespula germanica
Vespula maculifrons
Vespula pennsylvanica
Vespula squamosa
Vespula vidua
Vespula vulgaris
Myrmecia pilosula
Solenopsis geminata
Solenopsis invicta
Solenopsis saevissima
Triatoma protracta
Gadus callarias
Salmo salar
Bos domesticus
Gallus domesticus
Metapenaeus ensis
Penaeus aztecus
Penaeus indicus
Penaeus monodon
Todarodes pacificus
Helix aspersa
Haliotis midae
Rana esculenta
Brassica juncea
Brassica napus
Brassica rapa
Hordeum vulgare
Secale cereale
Triticum aestivum
Zea mays
Oryza sativa
Apium gravaolens
Daucus carota
Corylus avellana
Malus domestica
Pyrus communis
Persea americana
Prunus armeniaca
Prunus avium
Prunus domestica
Prunus persica
Asparagus officinalis
Asparagus
Crocus sativus
Vitis vinifera
Musa x paradisiaca
Ananas comosus
Citrus limon
Citrus sinensis
Litchi chinensis
litchi
Sinapis alba
Glycine max
Vigna radiata
Arachis hypogaea
Lens culinaris
Pisum savitum
Actinidia chinensis
Capsicum annuum
Lycopersicon esculentum
Solanum tuberosum
Bertholletia excelsa
Juglans nigra
Juglans regia
Anacardium occidentale
Ricinus communis
Sesamum indicum
Cucumis melo
Anisakis simplex
Argas reflexus
Ascaris suum
Carica papaya
papaya
Dendronephthya nipponica
Hevea brasiliensis
Homo sapiens
Triplochiton scleroxylon
With the present splicing/head to tail modification significant reduction in allergenic activity can be obtained. Depending on the method, this activity can mostly be extinguished from the wild-type protein allergen. According to a preferred embodiment of the present invention, reduction in allergenic activity is measured by a reduction of inhibition of IgE binding capacity of at least 10%, preferably at least 20%, especially at least 30%, compared to the wild-type allergen. A preferred method is shown in the example section below.
An alternative, but also preferred way for defining the reduction in allergenic activity uses measurement of IgE binding. Lack of binding of IgE antibodies of allergen sensitised patient's sera to a dot blot of said derivative is taken as an indication of most significant reduction. Also this method is shown in the example section below.
The derivatives obtained according to the present invention may be easily combined with a pharmaceutically acceptable excipient and finished to a pharmaceutical preparation.
Preferably, the derivatives are combined with a suitable vaccine adjuvant and finished to a pharmaceutically acceptable vaccine preparation.
According to a preferred embodiment, the derivatives according to the present invention are combined with further allergens to a combination vaccine. Such allergens are preferably wild-type allergens, especially a mixture of wild-type allergens, recombinant wild-type allergens, derivatives of wild-type protein allergens or mixtures thereof. Such mixtures may be made specifically for the needs (allergen profile) of a certain patient.
In a preferred embodiment, such a pharmaceutical preparation further contains an allergen extract.
According to another aspect of the present invention, an allergen derivative of a wild-type protein allergen is provided, said wild-type protein allergen having an amino acid sequence of 1 to Z, characterized in that said derivative adjacently contains—in N-terminus to C-terminus orientation—the two wild-type allergen fragments X to Z and 1 to X, said two wild-type allergen fragments having reduced allergenic activity or lacking allergenic activity.
Preferably, the allergen derivative according to the present invention is characterized in that X to Z and 1 to X are at least 30 amino acid residues long, preferably at least 50 amino acid residues, especially at least 60 amino acid residues.
It is even more preferred, if X to Z and 1 to X differ in length by 50% or less, preferably by 30% or less, especially by 20% or less.
Specifically preferred allergen derivatives according to the present invention are selected from a type I allergen, preferably from an allergen of table A, more preferred of timothy grass (Phelum pratense) pollen, especially Phl p 12, birch (Betula verrucosa) pollen, especially Bet v 2 and Bet v 4, yellow jacket (Vespula vulgaris) venom, paper wasp (Polistes annularis) venom, Parietaria judaica pollen, ryegrass pollen, dustmite allergens, especially Der p 2, etc.
Preferably, the derivatives according to the present invention are provided as a allergen composition wherein not only one allergen is present, but two or more. The present derivatives may also be mixed with allergen extracts which are supplemented by the derivatives of the present invention to substitute for the lack of sufficient amounts of specific allergens in the natural extracts. Mixtures of allergens are specifically needed in patients which have allergenic reactions to not only one allergen. It is therefore preferred to provide the present derivatives as in combination with further (other) allergens to a combination vaccine.
The allergen derivatives according to the present invention may therefore be preferably combined with wild-type allergen to an allergen composition, especially a mixture of a wild-type allergens, recombinant wild-type allergens, derivatives of wild-type protein allergens or mixtures thereof (each of the same and/or different allergen and/or isoforms or mutants thereof; as long as an overall reduction of allergenic activity, compared to the wild-type protein or recombinant allergen is given in the preparation as a whole).
Preferably, the present preparation further contains an allergen extract.
The allergen or allergen composition according to the present invention preferably contains a pharmaceutically acceptable excipient.
Another aspect of the present invention relates to the use of an allergen derivative according to the present invention for the preparation of an allergen specific immunotherapy medicament.
Yet another aspect of the present invention relates to the use of an allergen derivative or an allergen composition according to the present invention for the preparation of a medicament for the passive immunisation.
Another aspect of the present invention relates to the use of an allergen derivative or an allergen composition according to the present invention for the preparation of a medicament for the prophylactic immunisation.
The allergen derivatives and compositions according to the present invention can be used for the prophylactic immunisation of individuals leading to an effective prevention of allergy. Since the allergen derivatives and compositions according to the present invention, like Der p 2 allergen derivatives, show a reduced allergic immune response compared to the wild-type allergen, they do not lead to undesired side effects. Advantageously such a medicament may be administered to children at the age of 1 to 3 years. Such a vaccination before said child will get in contact with allergens prevents the formation of allergen specific IgE antibodies in said child.
Preferably, the medicament further contains other suitable ingredients, such as adjuvants, diluents, preservatives, etc.
According to a preferred embodiment of the present invention the medicament comprises 10 ng to 1 g, preferably 100 ng to 10 mg, especially 0.5 μg to 200 μg of said recombinant allergen derivative per application dose. Preferred ways of administration include all standard administration regimes described and suggested for vaccination in general and allergy immunotherapy specifically (orally, transdermally, intraveneously, intranasally, via mucosa, etc). The present invention includes a method for treating and preventing allergy by administering an effective amount of the pharmaceutical preparations according to the present invention.
Another aspect of the present invention relates to a method for producing an allergen derivative according to the present invention which is characterized in by the following steps:
Preferably, said host is a host with high expression capacity.
As used herein, a “host with high expression capacity” is a host which expresses a protein of interest in an amount of at least 10 mg/l culture, preferably of at least 15 mg/l, more preferably of at least 20 mg/l. Of course, the expression capacity depends also on the selected host and expression system (e.g. vector). Preferred hosts according to the present invention are E.coli, Pichia pastoris, Baciullus subtilis, pant cells (e.g. derived form tabacco) etc.
Of course, the allergen derivatives according to the present invention can also be produced by any other suitable method, especially chemical synthesis or semi-chemical synthesis.
Another aspect of the present invention relates to the use of a profilin derivative obtainable from a first wild-type profilin molecule by a method according to the present invention or an allergen derivative of a first wild-type profilin molecule according to the present invention for the manufacture of a medicament for the prevention or the treatment of allergic diseases caused by a second wild-type profilin molecule.
It turned surprisingly out that antibodies induced by an directed to profilin derivatives of a first wild-type profilin molecule according to the present invention bind also to other wild-type profilin molecules. Therefore said derivatives can be employed for the treatment or prevention of a number of allergic diseases. Such profilin derivatives may be used as broad spectrum vaccines which allow to immunize individuals with only one or two immunogenic molecules. Profilin represents an allergen that is expressed in all eukaryotic cells and thus represents a pan-allergen that might induce inhalative allergies (e.g. rhinoconjunctivits, asthma) as well as oral allergy syndromes after oral ingestion (itching and swelling of lips and the tounge) in sensitized patients.
For instance, the reshuffled Phl p 12-derivative, MP12, induces IgG antibodies after immunization that recognize profilins from both pollens as well as form plant-derived food. MP 12-induced antibodies inhibit patients' serum IgE binding to profilins from pollens and also to plant food-derived profilin. Thus, the MP12 as well as other reshuffled profilin molecules are suitable for the treatment of pollen-food cross-sensitization attributable to profilin allergy.
According to a preferred embodiment said first and said second profilin molecules are selected from the group consisting of Phl p 12, Bet v 2, Art v 4, Ana c, Api g 4, Mus xp 1, Cor a 2, and Dau c 4.
Especially these allergens are suited to be used according to the present invention because of their structural similarities. However, it is obvious that also other allergens which share structural similarities among each other can be used accordingly.
Said first profilin molecule is preferably Phl p 12 and said second profilin molecule is preferably selected from the group consisting of Bet v 2, Art v 4, Ana c, Api g 4, Mus xp 1, Cor a 2, and Dau c 4.
Experiments revealed that especially derivatives of Phl p 12 can be used as broad spectrum vaccines. A particular preferred derivative consists of a fusion protein, wherein amino acids 1 to 77 of the wild-type Phl p 12 are N-terminally fused to amino acids 78 to 131 (see
Profilin derivatives of Bet v 2, Art v 4, Ana c, Api g 4, Mus xp 1, Cor a 2, and Dau c 4 as disclosed herein and obtainable by a method according to the present invention are preferably used for the treatment and/or prevention of pollen-food sensitization attributable to profilin allergy.
The present invention is further described by the following examples and the drawing figures, yet without being restricted thereto.
In examples 1 to 5 the principles of the present invention are exemplified by a profilin allergen, timothy grass pollen profilin Phl p 12. Examples 6 to 11 relate to the main mite (Dermatophagoides pteronyssinus) allergen, Der p 2. Examples 12 and 13 show the cross reactivity of Phl p 12 with profilins of other sources than timothy grass pollen, demonstrating consequently the suitability for using Phl p 12 derivatives as vaccines for allergic diseases caused by other profilins.
a) Generation, Expression and Purification of a Hypoallergenic Variant from Timothy Grass Pollen Profilin, Phl p 12
Overlapping PCR technique was used for engineering a reshuffled Phi p 12-derivative. PCR template was the cDNA coding for timothy grass pollen profilin, Phl p 12, subcloned in pet17b expression vector. The following primers were used to generate two PCR fragments containing overlapping sequences as well as NdeI and EcoRI restriction sites and a sequence coding for a C-terminal 6× Histidin residue for protein purification. For fragment 1 primer MDE-1: 5′CATATGAGGCCCGGCGCGGTCATC3′ and primer MDE-2: 5′GTACGTCTGCCACGCCATCATGCCTTGTTCAAC3′ were used, for fragment 2, primer MABC-1: 5′GTTGAACAAGGCATGATGTCGTGGCAGACG3′ and primer MABC-2: 5′GAATTCTTAATGGTGATGGTGATGGTGACCCTGGATGACCATGTA3′ were used. In the next step, both PCR products obtained as described were used as templates for the overlapping PCR reaction using primer MDE-1 and MABC-2 to generate the DNA coding for the Phl p 12 derivative (i.e., MP12) (schematically represented in
For protein purification, MP12-encoding cDNA had to be subcloned into an pet17b expression vector system using NdeI and EcoRI restricition enzymes and the DNA sequence was again confirmed by double-strand sequencing (MWG Biotech).
For protein purification MP-12 was expressed in Escherichia coli BL21 (DE3) (Stratagene, East Kew, Australia) in liquid culture. E.coli were grown to an OD600 of 0.4 in LB-medium containing 100 mg/l ampicillin. The expression of recombinant proteins was induced by adding isopropyl-b-thiogalactopyranoside to a final concentration of 1 mM and further culturing for additional 4 hours at 37° C. E.coli cells from a 500 ml culture were harvested by centrifugation, resuspended in buffer A (100 mM NaH2PO4, 10 mM Tris, 8M Urea, pH 7.5). After centrifugation at 20.000 rpm, 30 min, the supernatant was transferred to a Ni-NTA agarose column (Quiagen, Hilden, Germany) and elution of the 6×His-tagged MP12 protein was performed using buffer A with decreasing pH values. The protein eluted at a pH of 4.9 and was subsequently refolded by stepwise dialysis against buffer A, pH 7.5, containing 6-0 M Urea. The final dialysis step was done against phosphate buffered saline (PBS), where MP12 was soluble as shown by centrifugation experiments.
Protein purity was confirmed by SDS PAGE and quantification was performed using a Micro BCA kit (Pierce, USA).
Circular dichroism (CD) measurements were carried out on a Jasco J-715 spectropolarimeter using a 0.1 cm pathlength cell equilibrated at 20° C. Spectra were recorded with 0.5 nm resolution at a scan speed of 100 nm/min and resulted from averaging 3 scans. The final spectra were baseline-corrected by substracting the corresponding MilliQ spectra obtained under identical conditions. Results were fitted with the secondary structure estimation program J-700.
The results indicate a considerable amount of secondary structure of the derivative. The spectrum of Phl p 12 is characterized with a minimum at 218 nm and a strong maximum below 200 nm, whereas the minimum of the derivative is shifted to a smaller wavelength and the zero-crossing of the curve is below 200 nm (
Affinity to polyproline is a feature common to profilins from various organisms. It was demonstrated that the hypoallergenic Phi p 12 derivative, MP12, does not bind polyproline and thus exhibits altered biochemical properties.
Approximately 5 μg of purified recombinant MP12 in PBS was subjected to a polyproline-loaded CnBr-activated agarose column (Amersham Bioscience, Uppsala, Sweden) equilibrated with PBS. After collecting the flow-through, the column was washed with 3 volumes (PBS) and elution was performed with 5×1 ml PBS containing 2M or 6M Urea, respectively. Ten μl aliquots of the flow-through, the wash fractions and elution fractions were subjected to a 14% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS PAGE) and proteins were visualized by Commassie staining (
The IgE binding capacity of recombinant MP12 was compared to that of recombinant Phl p 12 wild-type by dot blot analysis using sera from 24 profilin sensitised patients (
To quantify the reduction of IgE binding capacity of MP12, fluid phase inhibitions were performed. For this purpose serum from six profilin-sensitised patients were preincubated with either 10 μg of Phl p 12 and of MP12 and subconsequently incubated with ELISA plate-bound Phl p 12 (5 μg/ml). Bound IgE antibodies were detected with an alkaline phosphatase-labeled anti-human IgE antibody (Pharmingen). Inhibition of IgE binding was calculated with the following formula: Inhibition %=100×[(A−B)/A]; A representing OD values obtained after incubation of serum with BSA, B representing OD values after incubation of serum with Phl p 12 or MP12, respectively.
The ability of MP12 to inhibit binding of IgE to Phl p 12 is shown as percentage inhibition in Table 2, ranging from 20-40% with mean inhibition of 31.2% for MP12, whereas inhibition achieved with Phl p 12 ranged from 76-91% (mean 86%).
TPGQCNMVVERLGDYLVEQGM
MEPGAVIRGKKGAGGITIKKTGQALVGIYDEPMTPGQ
CNMVVERLGDYLVEQGM
MSWQTYVDEHLMCEIEGH
Next, the reshuffled Phl p 12 was compared with Phl p 12 wild-type for its capacity to induce histamine release from basophils from profilin allergic patients.
Granulocytes were isolated from heparinised blood samples of timothy grass pollen allergic patients by Dextran sedimentation. After isolation, cells were incubated with various concentrations of Phl p 12, MP12 or, for control purposes, with a monoclonal anti-human IgE antibody (Immunotech, Marseille, France). Histamine released into the supernatant was measured by radioimmunoassay (Immunotech). Total histamine was determined after freeze thawing of cells. Results are expressed as mean values of duplicate determinations, and represent the percentage of total histamine.
As exemplified in
In order to test, whether immunisation with reshuffled Phl p 12 will induce IgG antibodies that react with Phl p 12 wild-type and profilins from other pollens, rabbits were immunized three times with Phl p 12 or MP12 using Freund's complete and incomplete adjuvants (200 μg/injection) (Charles River, Kisslegg, Germany). Serum samples were obtained in four weeks intervals. Sera were stored at −20° C. until analysis.
Reactivity of MP12 and Phl p 12-induced IgG antibodies was studied by ELISA (
MP12 induced an IgG anti-Phl p 12 antibody response, that was comparable to that induced with Phl p 12 wild-type (
The ability of MP12-induced rabbit IgG to inhibit the binding of allergic patients' IgE to Phl p 12 was investigated by ELISA competition assay. ELISA plates (Nunc Maxisorp, Rosklide, Denmark) were coated with Phl p 12 (1 μg/ml) and preincubated either with a 1:250 dilution of each of the anti-MP12 antiserum or the Phl p 12-antiserum and, for control purposes, with the corresponding preimmune sera. After washing, plates were incubated with 1:3 diluted sera from seven Phl p 12-sensitised grass pollen allergic patients and bound IgE antibodies were detected with a monoclonal rat anti-human IgE antibody (Pharmingen, San Diego, Calif.), diluted 1:1000, followed by a 1:2000 diluted HRP-coupled sheep anti-rat Ig antiserum (Amersham). The percentage inhibition of IgE binding achieved by preincubation with the anti-peptide or anti-mutant antisera was calculated as follows: % inhibition of IgE binding=100−ODI/ODP×100. ODI and ODP represent the extinctions after preincubation with the rabbits' immune sera and the corresponding preimmune sera, respectively.
As shown in Table 3, inhibition of patients' IgE binding to Phl p 12 achieved with anti-Phl p 12 antibodies was between 30.2-66.7% (49.8% mean inhibition). Likewise, considerable reduction of anti-Phl p 12 IgE reactivity was observed, ranging from 10.8-27.6% (20.8% mean inhibition) with antibodies raised against MP12 (Table 3).
RBL-2H3 cells were plated in 96 well tissue culture plates (4×104 cells/well), incubated for 24 h at 37° C. using 7% CO2. Passive sensitisation was performed with mouse sera containing profilin-reactive IgE at a final dilution of 1:30 for 2 h. Unbound antibodies were removed by washing the cell layer 2 times in Tyrode buffer (137 mM NaCl, 2.7 mM KCl, 0.5 mM MgCl2, 1.8 mM CaCl2, 0.4 mM NaH2PO4, 5.6 mM D-glucose, 12 mM NaHCO3, 10 mM HEPES and 0.1% w/v BSA, pH 7.2). RBL cells, preloaded with Phl p 12-specific mouse IgE were exposed to rPhl p 12 (0.005 μg/ml). Phl p 12 was preincubated in Tyrode's buffer with 0, 2, 5, 7.5 or 10% v/v of rabbit antiserum from a Phl p 12-immunized rabbit, a MP12-immunized rabbit or the corresponding preimmune sera for 2 h at 37° C.
Preincubated Phl p 12 was added to the RBL cells for 30 min in a humidified atmosphere at 37° C. and their supernatants were analyzed for 8-hexosaminidase activity by incubation with 80 μM 4-methylumbelliferyl-N-acetyl-β-D-glucosamide (Sigma-Aldrich, Vienna, Austria) in citrate buffer (0.1M, pH 4.5) for 1 h at 37° C. The reaction was stopped by addition of 100 μl glycine buffer (0.2M glycine, 0.2M NaCl, pH 10.7) and the fluorescence was measured at λex: 360/λem: 465 nm using a fluorescence microplate reader (Spectrafluor, Tecan, Austria). Results are reported as fluorescence units and percentage of total β-hexosaminidase released after lysis of cells with 1% Triton X-100.
As exemplified in
House dust mite (HDM) allergy belongs to the most common allergies worldwide which affects more than 50% of all allergic patients. Dermatophogoides pteronyssinus was identified as the most important source of allergens in house dust in Europe.
Twenty groups of mite allergens have been characterized so far, and group 2 allergens were identified as the major mite allergens, against which more than 80% of mite allergic patients are sensitized and they are mainly localized in mite faeces. Group 2 allergens were first characterized as 14000-18000 Da allergens with a high IgE-binding activity. Isolation and analysis of cDNA clones coding for Der p 2, revealed then that Der p 2 comprises an allergen with 129 amino acid residues, a calculated molecular weight of 14000 Da and without N-glycosylation sites. Group 2 allergens contain three disulfide bonds and are composed of two anti-parallel β-sheets. T-cell epitopes of Der p 2 are located in all regions of the protein and IgE-epitopes were shown to be conformational.
Immunotherapy studies with crude mite extracts have demonstrated that dangerous systemic side effects may occur during immunotherapy with HDM-extracts (Akcakaya, N., et al. (2000) Ann Allergy Asthma Immunol 85:317) as well as the induction of new IgE reactivities to sea-foods (van Ree, R., et al. (1996) Allergy 51:108).
To overcome the disadvantages of extract-based immunotherapy, several strategies have been applied to develop hypoallergenic allergen derivatives. In case of Der p 2, variants were developed with reduced IgE reactivity by destroying disulfide bonds by site-directed mutagenesis, by destroying the disulfide bonds through N- and C-terminal deletion, or by introducing mutations. However, their biological activity is questionable.
In the following examples two recombinant fragments of the group 2 allergen of Dermatophagoides pteronyssinusm (Der p 2) comprising aa 1-53 and aa 54-129, to destroy conformational B-cell epitopes and to retain the major T-cell epitopes, were produced. Additionally, a recombinant Der p 2 hybrid molecule (aa 54-129+1-53), in which the two rDer p 2 fragments were recombined in inverse order by PCR-based gene-SOEing, was constructed.
Two recombinant fragments of Der p 2 comprising amino acids (aa) 1-53 and aa 54-129 were constructed by PCR-amplification as outlined in example 1 (see
a) Expression in E. coli and Purification of Der p 2, Der p 2 Fragments and Der p 2 Hybrid
cDNAs coding for His-tagged Der p 2, Der p 2 fragments (aa 1-53 and aa 54-129) and Der p 2 hybrid (aa 54-129+1-53) were generated by PCR amplification using primers (MWG, Ebersberg, Germany) as indicated in Table 4 and a Der p 2 cDNA was obtained by reverse transcription from Der p RNA.
TTCAATTTTAGCGGT-3′
ATCGCGGATTTTA-3′
Forward (F), reverse (R) and overlapping primers are indicated. The EcoRI sites and NdeI sites are underlined. Nucleotides coding for the His-tags are shown in bold/italic letters.
Primers 1 and 4 were used for the amplification of the rDer p 2 cDNA, primers 1 and 2 for the cDNA coding for rDer p 2 fragment 1 (aa 1-53) and primers 3 and 4 for the cDNA of the rDer p 2 fragment 2 (aa 54-129). rDer p 2 hybrid was generated by PCR-based gene-SOEing using primers 2 and 3 and the two overlapping primers 5 and 6. Upstream primers contained an NdeI and EcoRI site and downstream primers contained an EcoRI site as well as six His codons. PCR products were cut with NdeI/EcoRI, gel-purified and subcloned into the NdeI/EcoRI sites of plasmid pET17b. Calcium chloride method was used for the transformation of the plasmids into E.coli strain XL-1 Blue. Plasmid DNA was isolated by NuceloBond AX kit-maxi-prep (Macherey-Nagel, Germany) and the sequence of the cDNA inserts was confirmed by sequencing of both DNA strands on an automated sequencing system (MWG, Germany).
Recombinant proteins containing C-terminal Hexahistidine-tails were expressed in E.coli strain BL21 (DE3) in liquid culture by induction with 0.5 mM isopropyl-β-thiogalactopyranoside (IPTG) at an OD600 of 1 for 5 h at 37° C. Cells were harvested by centrifugation at 4,000×g for 15 minutes at 4° C.
The bacterial pellets obtained from 11 liquid culture were resuspended in 10 ml 25 mM imidazol, pH 7.4, 0.1% v/v Triton X-100 and treated with 100 μg lysozyme for 30 minutes at room temperature. Cells were lysed by 3 freeze/thawing cycles (−70° C./+50° C.), DNA was degraded by incubation with 1 μg DNase I for 10 minutes at room temperature and cell debris were removed by centrifugation at 10,000×g for 30 minutes at 4° C. rDer p 2 fragment 1 was found in the soluble fraction and purified under native conditions over Ni-NTA resin affinity columns (QIAGEN, Germany).
rDer p 2, rDer p 2 fragment 2 and rDer p 2 hybrid were found in the pellet in the inclusion body fraction, which was solubilized with 8M urea, 100 mM NaH2PO4, 10 mM Tris-Cl, pH 8 for 60 minutes at room temperature. Insoluble residues were removed by centrifugation (10,000×g, 15 min, 4° C.) and rDer p 2, rDer p 2 fragment 2 and rDer p 2 hybrid were purified under denaturating conditions over Ni-NTA resin affinity columns (QIAGEN).
Fractions, containing recombinant proteins of more than 90% purity were dialysed against 50 mM NaH2PO4 pH 7 and the final protein concentrations were determined by Micro BCA Protein Assay Kit (Pierce, USA).
The construction of a hybrid molecule as outlined above disrupted at least one of the two β-sheets of Der p 2 and the disulfide bond between C8 and C119 and thus the conformational IgE epitopes of Der p 2 destroyed and major T-cell epitopes preserved. The rDer p 2 derivatives were overexpressed as visible bands in E. coli yielded a distinct accumulation (
b) Matrix-Assisted Laser Desorption and Ionization-Time of Flight (MALDI-TOF) Mass Spectrometry of rDer p 2 and rDer P 2 Derivatives
Laser desorption mass spectra were acquired in a linear mode with a time of-flight Compact MALDI II instrument (Kratos, U.K.; piCHEM, Austria). Samples were dissolved in 10% acetonitrile, 0.1% trifluoroacetic acid and Alfa-cyano-4 hydroxy-cinnamic acid (dissolved in 60% acetonitrile, 0.1% trifluoroacetic acid) was used as a matrix. For sample preparation, a 1:1 mixture of protein and matrix solution was deposited onto the target and air-dried.
Analysis of the four proteins by MALDI-TOF mass spectrometry revealed molecular masses of 15072.9 Da, 6806.7 Da, 9216.3 Da and 15001.8 Da for rDer p 2, rDer p 2 fragment 1, rDer p 2 fragment 2 and rDer p 2 hybrid, respectively, which are in agreement with the theoretical masses of the proteins calculated from their amino acid sequences (
The CD spectra of the purified recombinant proteins were recorded on a JASCO J715 spectropolarimeter that had been wavelength calibrated with neodymium glass in accordance with the manufacturer's suggestions. CD measurements were performed with rDer p 2 and rDer p 2 derivatives (c=0.1 to 0.5 mg/ml) dissolved in double distilled water at room temperature. A circular quartz cuvette with a path length of 0.1 cm was used and the spectra were recorded with 0.2 nm resolution at a scan speed of 50 nm/min. The spectra were signal-averaged by accumulating at least three scans and the results are expressed as the mean residue ellipticity at a given wavelength.
The far ultraviolet CD spectrum of the purified recombinant Der p 2 shows a negative band at 217 nm, indicating a β-sheet conformation (
Purified recombinant Der p 2, the two rDer p 2 fragments, fragment 1 (aa 1-53) and fragment 2 (aa 54-129), and rDer p 2 hybrid were tested for IgE reactivity by non-denaturating dot blot assays. Two microlitres of the purified proteins (0.1 mg/ml) and, for control purposes, BSA were dotted onto nitrocellulose membrane strips (Schleicher & Schuell, Germany). Nitrocellulose strips containing the dot-blotted proteins were blocked in buffer A (40 mM Na2HPO4, 0.6 mM NaH2PO4, pH 7.5, 0.5% [v/v] Tween 20, 0.5% [w/v] BSA, 0.05% [w/v] NaN3) and incubated with sera from mite-allergic patients, serum from a non-allergic person (dilutions 1:10) or buffer A without serum. Bound IgE antibodies were detected with 125I-labeled anti-human IgE antibodies and visualized by autoradiography.
The IgE-binding capacity of rDer p 2 wild-type allergen was compared with the two rDer p 2 fragments and rDer p 2 hybrid by non-denaturing dot blot assays. Sera from 17 mite allergic individuals (lanes 1-17) showed varying IgE reactivity to nitrocellulose dotted rDer p 2, whereas almost no IgE reactivity to rDer p 2 fragment 1 could be detected. Only 3 sera showed very weak binding to rDer p 2 fragment 2 and 2 sera reacted with rDer p 2 hybrid (
Heparinized blood samples were obtained from allergic patients. Blood samples (100 μl) were incubated with various concentrations of rDer p 2, rDer p 2 fragments, rDer p 2 hybrid, a monoclonal anti-IgE antibody (Immunotech, Marseille, France), or PBS for 15 minutes (37° C.). CD 203c expression was determined as described (Hauswirth, A. W., et al. (2002) J Allergy Clin Immunol 110:102.).
The upregulation of CD 203c has been described as a surrogate marker for allergen-induced basophil activation and degranulation (Hauswirth, A. W., et al. (2002)). Therefore the allergenic activity of recombinant Der p 2, rDer p 2 fragments and rDer p 2 hybrid by measuring CD 203c upregulation on basophils from house dust mite allergic patients was compared (
Anti-human IgE antibodies induced upregulation of CD 203c expression on basophils from all patients, whereas no upregulation was obtained with buffer alone (FIG. 13+14).
Determination of CD 203c expression on basophils from mite-allergic patients indicates a reduced biological activity of rDer p 2 hybrid compared to rDer p 2 wild-type and no biological activity can be observed with the rDer p 2 fragments. Moreover, basophil activation assays using RBL cells indicate that IgE Abs induced with the derivatives were less anaphylactic. These results indicate that hypoallergenic rDer p 2 derivatives will induce less IgE-mediated side-effects than the Der p 2 wild-type allergen when used for immunotherapy.
Groups of five eight-week-old female BALB/c mice each were immunized with 5 μg of purified proteins (rDer p 2, rDer p 2 fragment 1, rDer p 2 fragment 2 or rDer p 2 hybrid), adsorbed to 200 μl of AluGel-S (SERVA Electrophoresis, Germany) subcutaneously in the neck in 4 weeks intervals over a period of 20 weeks. Blood samples were collected one day before each immunization and stored at −20° C.
ELISA plates (Greiner, Austria) were coated with rDer p 2 diluted in PBS (c=5 μg/ml) over night at 4° C. The plates were washed twice with PBST (PBS; 0.05% v/v Tween 20) and blocked with blocking buffer (PBST; 1% w/v BSA) for 3 h at room temperature. Mouse sera were diluted 1:1000 for measurement of Der p 2-specific IgG1 in PBST; 0.5% w/v BSA and 100 μl of this dilution was added per well overnight at 4° C.
Plates were washed 5 times with PBST and bound IgG1 antibodies were detected with a monoclonal rat anti-mouse IgG1 antibody (BD Pharmingen, USA), followed by the addition of horseradish peroxidase-labeled goat anti-rat IgG antibodies (Amersham Bioscience, Sweden) as described (Vrtala, S., et al. (1996) J Allergy Clin Immunol 98:913).
The Der p 2 specific IgG1 levels were determined in serum samples obtained from mice after immunization with rDer p 2 and rDer p 2 derivatives (
ELISA plates (Greiner, Austria) were coated with 100 μl purified rDer p 2, diluted with PBS to a concentration of 5 μg/ml, over night at 4° C. After washing twice with PBST and blocking with blocking buffer (PBST; 1% w/v BSA) for 3 h at room temperature, plates were incubated overnight at 4° C. with anti-rDer p 2, anti-rDer p 2 fragment 1, anti-rDer p 2 fragment 2 or anti-rDer p 2 hybrid antisera or the corresponding preimmune sera. Mouse anti-sera were diluted 1:20 and rabbit antisera were diluted 1:100 in PBST; 0.5% w/v BSA. After washing, the plates were incubated with 1:10 diluted sera from mite allergic patients overnight at 4° C. and bound human IgE antibodies were detected with HRP-coupled goat anti-human IgE antibodies (KPL, USA) diluted 1:2500 in PBST; 0.5% w/v BSA as described (44, 45). The percentage of inhibition of IgE binding was calculated as follows: 100−(ODs/ODp)×100, where ODs and ODp represent the extinction coefficients after preincubation with the immune serum and the preimmune serum, respectively.
Mouse IgG1 antibodies induced by immunization with rDer p 2 and the rDer p 2 derivatives were investigated for their ability to inhibit mite-allergic patients' IgE binding to rDer p 2 in ELISA competition experiments.
The percentage of inhibition of allergic patients' IgE binding to rDer p 2 wild-type by mouse IgG antibodies is shown in Tables 5 and 6.
The inhibition obtained with mouse anti-rDer p 2 antibodies was between 61 and 87% (mean 75%), whereas mouse anti-rDer p 2 hybrid antibodies, anti-Der p 2 fragment 1 antibodies and anti-Der p 2 fragment 2 antibodies inhibited serum IgE binding to rDer p 2 wild-type between 47 and 76% (mean 62%), between 48 and 66% (mean 54%) and between 24 and 52% (mean 41%), respectively (Table 5).
In additional experiments, rabbits were immunized with purified rDer p 2 and the three rDer p 2 derivatives. The ability of rabbit anti-sera to inhibit mite-allergic patients' IgE binding to rDer p 2 was also tested by ELISA inhibition assays with an outcome similar as obtained for the mouse sera (Table 6). Rabbit anti-rDer p 2 antibodies inhibited patients' IgE binding to rDer p 2 between 47 and 89% (mean 66%), whereas anti-rDer p 2 hybrid antibodies inhibited human IgE binding between 20 and 86% (mean 59%). The inhibition obtained with rabbit anti-rDer p 2 fragment 1 antibodies was between 26 and 70% (mean 52%) and the inhibition with rabbit anti-rDer p 2 fragment 2 antibodies was between 32 and 54% (mean 42%). Using a mixture of the anti-fragment 1 and anti-fragment 2 antibodies the inhibition of patients' IgE binding to rDer p 2 wild-type was only slightly increased to a mean of 55% (Table 6).
Immunization of mice showed the immunogenicity of all three rDer p 2 derivatives by their capacity to induce IgG antibody responses. IgE-binding from mite-allergic patients to Der p 2 was inhibited by IgG antibodies induced with each of the rDer p 2 derivatives but rDer p 2 hybrid-induced IgG antibodies indicated a better inhibitory capacity compared to IgG antibodies induced with the two individual fragments and even to a mixture of fragment 1 and 2 induced IgG antibodies. These results are of importance, since blocking antibodies were shown to play a main role in SIT with recombinant allergens.
Anti-rDer p 2 and anti-rDerp 2 derivative antibodies induced by immunisation of mice inhibit allergic patients' IgE binding to rDer p 2 as shown in an ELISA inhibition assay.
Der p 2 Hybrid induces blocking antibodies in the present mouse model; immunogenicity is significantly increased by reshuffling the fragments.
Rat basophil leukemia (RBL) cells (subline RBL-2H3) were plated on ELISA plates (Nunc, Denmark) (100 μl: 4×104 cells) in cell culture medium (100 ml RPMI 1649, 10% FCS, 4 mM L-Glutamine, 2 mM Sodium Pyruvate, 10 mM HEPES, 100 μM 2-Mercaptoethanol, 1% Pen/Strep) over night at 37° C., 5% CO2.
Cells were loaded with 2 μl of serum obtained from mice immunized with rDer p 2, rDer p 2 fragment 1, rDer p 2 fragment 2 and rDer p 2 hybrid for 2 h at 37° C., washed twice with 200 μl Tyrode/BSA buffer (137 mM NaCl, 2.7 mM KCl, 0.5 mM MgCl2, 1.8 mM CaCl2, 0.4 mM NaH2PO4, 5.6 mM D-glucose, 12 mM NaHCO3, 10 mM N-2-hydroxyethyl-piperazine-N′-2-ethanesulfonic acid (HEPES), 0.1% bovine serum albumin, pH 7.2) (Sigma-Aldrich, Austria) and stimulated with rDer p 2 (c=0.3 μg/ml). Total β-hexosaminidase release was induced by addition of 1 μl 10% v/v Triton X-100 (Merck, Germany).
For measuring the release of β-hexosaminidase, 50 μl assay solution (80 μM 4-methylumbelliferyl-N-acetyl-β-D-glucosaminide in 0.1M citrate buffer, pH 4.5) was incubated with 50 μl supernatant for 1 h at 37° C., 5% CO2.
The reaction was stopped by adding 100 μl glycin buffer (0.2M glycine, 0.2M NaCl, pH 10.7) and fluorescence was measured at ex: 360 nm λem: 465 nm using a fluorescence microplate reader (Dynatech MR 7000, Dynatech Laboratories, USA). Results are shown as mean percentages of total β-hexosaminidase release.
To investigate whether vaccination with rDer p 2 derivates induces allergic immune responses to Der p 2 wild-type allergen, mice were immunized with rDer p 2, rDer p 2 fragment 1, rDer p 2 fragment 2 and rDer p 2 hybrid, respectively. Then serum samples from the mice were used to load RBL cells to quantify the allergenic immune response to rDer p 2 wild-type allergen by RBL degranulation experiments. The release obtained with rDer p 2 wild-type allergen in RBLs loaded with mouse anti-rDer p 2 fragment 1, anti-rDer p 2 fragment 2 and anti-rDer p 2 hybrid antibodies was between 0 and 16.6% (mean 6.4%), between 0.2 and 28.6% (mean 13.2%) and between 4.7 and 37.1% (mean 18.3%), whereas RBLs, loaded with anti-rDer p 2 wild-type antibodies released between 35 and 39% (mean 37%) after stimulation with rDer p 2 wild-type (
In order to test whether antibodies induced after immunization with MP 12 recognize profilins from pollens as well as from plant derived food, ELISA experiments were performed.
Profilins from timothy grass pollen (Phl p 12), birch pollen (Bet v 2), mugwort pollen (Art v 4) and from different plant foods (cashew nut (Ana c), celery (Api g 4), banana (Mus xp 1), hazelnut (Cor a 2), and carrot (Dau c 4) were coated onto ELISA plates (5 μg/ml) and incubated with serial dilutions of rabbit antisera (1:2000-1:64000). Bound rabbit antibodies were detected with a POX-labeled donkey-anti-rabbit antiserum.
MP 12 induced an IgG antibody response that was comparable with that induced with Phl p 12 wild-type (
The ability of MP12-induced rabbit IgG to inhibit the binding of allergic patients' IgE to Phl p 12, to profilins from distinct pollens and to plant food-derived profilins was investigated by ELISA competition experiments.
ELISA plates (Nunc Maxisorp, Denmark) were coated with profilins from timothy grass (rPhl p 12), birch pollen (rBet v 1), carrot (rDau c 4), hazelnut (rCor a 2), banana (rMus xp 1) and cashew nut (rAna c 1) and preincubated with a 1:50 dilution of the anti-Phl p 12 antiserum, the anti-MP 12-antiserum and, for control purposes, with the corresponding preimmune sera. After washing, plates were incubated with 1:3 diluted sera from eight profilin-sensitized patients and bound IgE antibodies were detected with a HRP-labeled anti-human IgE antiserum from goat (KPL, USA), diluted 1:2500. The percentage inhibition of IgE binding achieved by preincubation with the anti-Phl p 12 and anti-MP 12-antisera was calculated as follows: % inhibition of IgE binding=100−ODI/ODP×100. ODI and ODP represent the extinctions after preincubation with the rabbits' immune sera and the corresponding preimmune sera, respectively (Table 7).
The mean inhibition of IgE binding to timothy grass pollen profilin achieved with Phl p 12-induced antibodies and MP 12-induced antibodies was comparable with 83.8% and 72.3%, respectively (Table 7). IgE binding to birch pollen profilin, Bet v 2, was even stronger inhibited with MP 12-specific antibodies (mean inhibition 74.5%) than with Phl p 12-induced antibodies (mean inhibition 64.8%). IgE binding to plant food profilins were inhibited with both antisera to a very similar degree (Cor a 2: 62.3% average inhibition with anti-Phl p 12-IgG, 58.1% with anti-MP 12-IgG; Dau c 4: 73.3% average inhibition with anti-Phl p 12-IgG, 74.6% with anti-MP 12-IgG; Ana c 1: 56.8% average inhibition with anti-Phl p 12-IgG, 53.6% with anti-MP 12-IgG). Only IgE binding to banana profilin, Mus xp 1, was less inhibited with anti-Mp 12-IgG (36.1%) than with anti-Phl p 12-induced IgG (71.4%) (Table 7).
Profilin represents an allergen that is expressed in all eukaryotic cells and thus represents a pan-allergen that might induce inhalative allergies (e.g., rhinoconjunctivits, asthma) as well as oral allergy syndromes after oral ingestion (itching and swelling of lips and the tounge) in sensitized patients.
The reshuffled Phl p 12-derivative, MP12, induces IgG antibodies after immunization that recognize profilins from both pollens as well as from plant-derived food. MP 12-induced antibodies inhibit patients' serum IgE binding to profilins from pollens and also to plant food-derived profilins. Thus, the MP12 is suitable for the treatment of pollen-food cross-sensitization attributable to profilin allergy.
Number | Date | Country | Kind |
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A 2028/2004 | Dec 2004 | AT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AT05/00486 | 12/2/2005 | WO | 00 | 5/31/2007 |