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Zheng W, Xu YF, Hu ZM, Li K, Xu ZQ, Sun JL, Wei JF. Artificial intelligence-driven design of the assembled major cat allergen Fel d 1 to improve its spatial folding and IgE-reactivity. Int Immunopharmacol 2024; 128:111488. [PMID: 38185034 DOI: 10.1016/j.intimp.2024.111488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/31/2023] [Accepted: 01/02/2024] [Indexed: 01/09/2024]
Abstract
BACKGROUND Cat-derived allergens are considered as one of the most common causes of allergic diseases worldwide. Fel d 1 is a major cat allergen and plays an important role in immunoglobulin E (IgE)-reaction diagnosis. However, the two separate chains of Fel d 1 exhibited lower IgE-reactivity than its complete molecule of an assembled form, which makes it difficult to efficiently prepare and limits the application of Fel d 1 in molecular diagnosis of cat allergy. METHODS We first applied artificial intelligence (AI) based tool AlphaFold2 to build the 3-dimensional structures of Fel d 1 with different connection modes between two chains, which were evaluated by ERRAT program and were expressed in Escherichia coli. We then calculated the expression ratios of soluble form/inclusion bodies form of optimized Fel d 1. The Circular Dichroism (CD), High Performance Liquid Chromatography-Size Exclusion Chromatography (HPLC-SEC) and reducing/non-reducing SDS-PAGE were performed to characterize the folding status and dimerization of the optimized fusion Fel d 1. The improvement of specific-IgE reactivity to optimized fusion Fel d 1 was investigated by enzyme linked immunosorbent assay (ELISA). RESULTS Among several linkers, 2 × GGGGS got the highest scores, with an overall quality factor of 100. The error value of the residues around the junction of 2 × GGGGS was lower than others. It exhibited highest proportion of soluble protein than other Fel d 1 constructs with ERRAT (GGGGS, KK as well as direct fusion Fel d 1). The results of CD and HPLC-SEC showed the consistent folding and dimerization of two fused subunits between the optimized fusion Fel d 1 and previously well-defined direct fusion Fel d 1. The overall IgE-binding absorbance of optimized fusion Fel d 1 tested by ELISA was improved compared with that of the direct fusion Fel d 1. CONCLUSION We firstly provided an AI-design strategy to optimize the Fel d 1, which could spontaneously fold into its native-like structure without additional refolding process or eukaryotic folding factors. The improved IgE-binding activity and simplified preparation method could greatly facilitate it to be a robust allergen material for molecular diagnosis of cat allergy.
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Affiliation(s)
- Wei Zheng
- Department of Pharmacy, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China
| | - Yi-Fei Xu
- Department of Pharmacy, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China
| | - Zhi-Ming Hu
- Department of Pharmacy, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China
| | - Ke Li
- Department of Pharmacy, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China
| | - Zhi-Qiang Xu
- Research Division of Clinical Pharmacology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China; National Vaccine Innovation Platform, Nanjing Medical University, Nanjing 211166, China.
| | - Jin-Lyu Sun
- Department of Allergy, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China.
| | - Ji-Fu Wei
- Department of Pharmacy, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China; Research Division of Clinical Pharmacology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China; National Vaccine Innovation Platform, Nanjing Medical University, Nanjing 211166, China.
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The Major Cat Allergen Fel d 1 Binds Steroid and Fatty Acid Semiochemicals: A Combined In Silico and In Vitro Study. Int J Mol Sci 2020. [PMID: 32085519 DOI: 10.3390/ijms21041365.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The major cat allergen Fel d 1 is a tetrameric glycoprotein of the secretoglobin superfamily. Structural aspects and allergenic properties of this protein have been investigated, but its physiological function remains unclear. Fel d 1 is assumed to bind lipids and steroids like the mouse androgen-binding protein, which is involved in chemical communication, either as a semiochemical carrier or a semiochemical itself. This study focused on the binding activity of a recombinant model of Fel d 1 (rFel d 1) towards semiochemical analogs, i.e., fatty acids and steroids, using both in silico calculations and fluorescence measurements. In silico analyses were first adopted to model the interactions of potential ligands, which were then tested in binding assays using the fluorescent reporter N-phenyl-1-naphthylamine. Good ligands were fatty acids, such as the lauric, oleic, linoleic, and myristic fatty acids, as well as steroids like androstenone, pregnenolone, and progesterone, that were predicted by in silico molecular models to bind into the central and surface cavities of rFel d 1, respectively. The lowest dissociation constants were shown by lauric acid (2.6 µM) and androstenone (2.4 µM). The specific affinity of rFel d 1 to semiochemicals supports a function of the protein in cat's chemical communication, and highlights a putative role of secretoglobins in protein semiochemistry.
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Bienboire-Frosini C, Durairaj R, Pelosi P, Pageat P. The Major Cat Allergen Fel d 1 Binds Steroid and Fatty Acid Semiochemicals: A Combined In Silico and In Vitro Study. Int J Mol Sci 2020; 21:ijms21041365. [PMID: 32085519 PMCID: PMC7073184 DOI: 10.3390/ijms21041365] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 12/16/2022] Open
Abstract
The major cat allergen Fel d 1 is a tetrameric glycoprotein of the secretoglobin superfamily. Structural aspects and allergenic properties of this protein have been investigated, but its physiological function remains unclear. Fel d 1 is assumed to bind lipids and steroids like the mouse androgen-binding protein, which is involved in chemical communication, either as a semiochemical carrier or a semiochemical itself. This study focused on the binding activity of a recombinant model of Fel d 1 (rFel d 1) towards semiochemical analogs, i.e., fatty acids and steroids, using both in silico calculations and fluorescence measurements. In silico analyses were first adopted to model the interactions of potential ligands, which were then tested in binding assays using the fluorescent reporter N-phenyl-1-naphthylamine. Good ligands were fatty acids, such as the lauric, oleic, linoleic, and myristic fatty acids, as well as steroids like androstenone, pregnenolone, and progesterone, that were predicted by in silico molecular models to bind into the central and surface cavities of rFel d 1, respectively. The lowest dissociation constants were shown by lauric acid (2.6 µM) and androstenone (2.4 µM). The specific affinity of rFel d 1 to semiochemicals supports a function of the protein in cat’s chemical communication, and highlights a putative role of secretoglobins in protein semiochemistry.
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Affiliation(s)
- Cécile Bienboire-Frosini
- Department of Molecular Biology and Chemical Communication (D-BMCC), Research Institute in Semiochemistry and Applied Ethology (IRSEA), Quartier Salignan, 84400 Apt, France;
- Correspondence: ; Tel.: +33-490-75-57-00
| | - Rajesh Durairaj
- Department of Molecular Biology and Chemical Communication (D-BMCC), Research Institute in Semiochemistry and Applied Ethology (IRSEA), Quartier Salignan, 84400 Apt, France;
| | - Paolo Pelosi
- Austrian Institute of Technology GmbH, Biosensor Technologies, Konrad-Lorenzstraße, 3430 Tulln, Austria;
| | - Patrick Pageat
- Department of Chemical Ecology (D-EC), Research Institute in Semiochemistry and Applied Ethology (IRSEA), Quartier Salignan, 84400 Apt, France;
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Dolgova AS, Sudina AE, Cherkashina AS, Stukolova OA. Component-resolved microarray analysis of IgE sensitization profiles to Felis catus major allergen molecules in Russian cat-allergic patients. Scandinavian Journal of Clinical and Laboratory Investigation 2017; 78:81-86. [PMID: 29228796 DOI: 10.1080/00365513.2017.1414955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We aimed to determine the profile of IgE reactivity to three major cat allergens, Fel d 1, Fel d 2 and Fel d 4, in cat-allergic patients in the Moscow region in Russia. sIgE levels to recombinant proteins expressed in Escherichia coli (Fel d 1 and Fel d 4) and to Fel d 2 protein purified from cat serum were measured using a microarray method developed in our laboratory. Sera from 174 anonymous subjects with a positive reaction (≥0.35 IU/mL) to cat dander extract (e1, ImmunoCAP) and 56 negative controls were used for IgE testing. Fel d 1 was recognized by 92.5%, Fel d 2 by 29.9% and Fel d 4 by 39.1% of the tested patient sera. The sensitivity to these three proteins was approximately 98% compared to cat dander extract (correlation coefficient to ImmunoCAP is 0.94 with PPV = 0.99 and NPV = 0.95). These predictive values appeared to be even more statistically significant than the divergence between the ISAC IgE test and the extract-based singleplex ImmunoCAP. The combination of the three investigated proteins (Fel d 1, Fel d 2 and Fel d 4) is suitable for in vitro molecular (serological) diagnosis of cat allergy in this region as a complement to cat dander extract. Moreover, with this method, we found distinction between Fel d 2 and other Feline sIgEs formation.
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Affiliation(s)
- Anna Sergeevna Dolgova
- a Molecular Diagnostics and Epidemiology Department , Central Research Institute of Epidemiology , Moscow , Russia
| | - Anna Evgenevna Sudina
- a Molecular Diagnostics and Epidemiology Department , Central Research Institute of Epidemiology , Moscow , Russia
| | | | - Olga Alekseevna Stukolova
- a Molecular Diagnostics and Epidemiology Department , Central Research Institute of Epidemiology , Moscow , Russia.,b Research Institute of Occupational Health , Moscow , Russia
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Nilsson OB, van Hage M, Grönlund H. Mammalian-derived respiratory allergens - implications for diagnosis and therapy of individuals allergic to furry animals. Methods 2013; 66:86-95. [PMID: 24041755 DOI: 10.1016/j.ymeth.2013.09.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 08/07/2013] [Accepted: 09/02/2013] [Indexed: 02/08/2023] Open
Abstract
Furry animals cause respiratory allergies in a significant proportion of the population. A majority of all mammalian allergens are spread as airborne particles, and several have been detected in environments where furry animals are not normally kept. The repertoire of allergens from each source belongs to a restricted number of allergen families. Classification of allergen families is particularly important for the characterization of allergenicity and cross-reactivity of allergens. In fact, major mammalian allergens are taken from only three protein families, i.e. the secretoglobin, lipocalin and kallikrein families. In particular, the lipocalin superfamily harbours major allergens in all important mammalian allergen sources, and cross-reactivity between lipocalin allergens may explain cross-species sensitization between mammals. The identification of single allergen components is of importance to improve diagnosis and therapy of allergic patients using component-resolved diagnostics and allergen-specific immunotherapy (ASIT) respectively. Major disadvantages with crude allergen extracts for these applications emphasize the benefits of careful characterization of individual allergens. Furthermore, detailed knowledge of the characteristics of an allergen is crucial to formulate attenuated allergy vaccines, e.g. hypoallergens. The diverse repertoires of individual allergens from different mammalian species influence the diagnostic potential and clinical efficacy of ASIT to furry animals. As such, detailed knowledge of individual allergens is essential for adequate clinical evaluation. This review compiles current knowledge of the allergen families of mammalian species, and discusses how this information may be used for improved diagnosis and therapy of individuals allergic to mammals.
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Affiliation(s)
- Ola B Nilsson
- Department of Medicine, Clinical Immunology and Allergy Unit, Karolinska Institutet, Stockholm, Sweden; Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Marianne van Hage
- Department of Medicine, Clinical Immunology and Allergy Unit, Karolinska Institutet, Stockholm, Sweden
| | - Hans Grönlund
- Department of Clinical Neuroscience, Therapeutic Immune Design Unit, Karolinska Institutet, Stockholm, Sweden.
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Glutaraldehyde-Modified Recombinant Fel d 1: A Hypoallergen With Negligible Biological Activity But Retained Immunogenicity. World Allergy Organ J 2011; 4:113-9. [PMID: 23268458 PMCID: PMC3488918 DOI: 10.1097/wox.0b013e3182228a39] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Background Recombinant allergens are under investigation for replacing allergen extracts in immunotherapy. Site-directed mutagenesis has been suggested as a strategy to develop hypoallergenic molecules that will reduce the risk of side effects. For decades, chemically modified allergen extracts have been used for the same reason. Aim To evaluate whether glutaraldehyde modification is a good strategy to produce hypoallergenic recombinant allergens with retained immunogenicity. Methods Fel d 1 was cloned as a single construct linking both chains of the molecule and expressed in Escherichia coli and Pichia pastoris. After physicochemical purification, recombinant Fel d 1 (rFel d 1) was chemically modified using glutaraldehyde. The effect of modification on immune reactivity was evaluated using radioallergosorbent test, CAP-inhibition, competitive radioimmunoassay, enzyme-linked immunosorbent assay, basophil histamine release, and T-cell proliferation assays. Both natural Fel d 1 and recombinant unmodified Fel d 1 were used as controls. Results rFel d 1 demonstrated similar IgE binding and biological activity as its natural counterpart. Upon modification, IgE-binding potency decreased to >1000-fold, which was translated into a >106-fold reduction in the biological activity assessed by basophil histamine release. In contrast, the modified recombinant did not show a decreased but even a moderately increased capacity (1.5-fold) to stimulate proliferation of T cells (P < 0.01). Finally, it induced specific IgG antibodies in rabbits that recognized the unmodified allergen. Conclusions Chemical modification is a practical and highly effective approach for achieving hypoallergenicity of recombinant allergens with retained immunogenicity.
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Smith W, O'Neil SE, Hales BJ, Chai TLY, Hazell LA, Tanyaratsrisakul S, Piboonpocanum S, Thomas WR. Two newly identified cat allergens: the von Ebner gland protein Fel d 7 and the latherin-like protein Fel d 8. Int Arch Allergy Immunol 2011; 156:159-70. [PMID: 21576986 DOI: 10.1159/000322879] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 11/12/2010] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Characterization of the complete IgE binding spectrum of cat allergens is important for the development of improved diagnosis and effective immunotherapeutics. While Fel d 1 remains unchallenged as the major cat allergen, we now report the isolation of two new allergens capable of binding similar concentrations of IgE in the allergic sera of some individuals. MATERIALS AND METHODS Cat tongue and submandibular salivary gland cDNA libraries were screened by DNA hybridisation and IgE immunoassay. The isolated DNA fragments were sub-cloned into an E. coli expression system and the IgE reactivity was examined with human cat-allergic sera using a DELFIA IgE quantitation assay. RESULTS Fel d 7, an 18 kDa von Ebner gland protein Can f 1 homologue, was isolated from the tongue library. Fel d 8, a 24-kDa latherin-like protein with homology to Equ c 5, was isolated from the submandibular library. The frequency of IgE binding of cat-allergic sera to recombinant Fel d 1, 7 and 8 was 60.5, 37.6 and 19.3%, respectively. Inhibition studies indicated some IgE binding cross-reactivity between Fel d 7 and dog dander extracts. DISCUSSION The study reports the isolation and characterization of two new cat allergens. The isolation of these allergens provides the opportunity to determine the role that IgE binding proteins other than Fel d 1 play in cat-allergic disease. For cat-allergic individuals with moderate to mild rhinoconjunctivitis these allergens may play a more important role in the manifestation of their allergic disease.
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Affiliation(s)
- W Smith
- Division of Molecular Biotechnology, Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, WA, Australia.
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Flow cytometry imaging identifies rare T(H)2 cells expressing thymic stromal lymphopoietin receptor in a "proallergic" milieu. J Allergy Clin Immunol 2010; 126:1049-58, 1058.e1-10. [PMID: 20888036 DOI: 10.1016/j.jaci.2010.07.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 07/21/2010] [Accepted: 07/23/2010] [Indexed: 01/24/2023]
Abstract
BACKGROUND Thymic stromal lymphopoietin (TSLP) is expressed at sites of allergic inflammation, including eczematous skin. This cytokine has been reported to exert its T(H)2-inducing properties through dendritic cells. Expression of TSLP receptor on the surface of activated T(H)2 cells could amplify T(H)2 responses at inflamed sites through the direct actions of TSLP. OBJECTIVE To test rigorously whether T(H)2 cells induced by "proallergic" factors express TSLP receptor and characterize these cells using an experimental platform that combines flow cytometry with microscopic capabilities. METHODS CD4(+) T cells isolated from patients with atopic dermatitis or normal healthy controls were cocultured with autologous dendritic cells in the presence of T(H)2-promoting stimuli (TSLP ± allergen and staphylococcal enterotoxin B ± TSLP). Surface expression of TSLP receptor was analyzed by image-based flow cytometry, and responsiveness of purified T cells to TSLP was assessed by phosphorylation of signal transducer and activator of transcription-5 and cytokine secretion. RESULTS T(H)2-promoting stimuli induced a robust population of activated T(H)2 cells (CD25(+)IL-4(+)). Regardless of the nature of the stimulus, flow cytometry imaging confirmed that T cells expressing TSLP receptor were rare, constituting a minor fraction of the IL-4(+) T cell pool; however, TSLP responsiveness was nonetheless detectable. Analysis of cell size and nuclear morphology revealed preferential expression of TSLP receptor on IL-4-expressing cells undergoing mitosis. Analysis of lesional skin in atopic dermatitis supported the view that rare IL-4(+) T cells expressing TSLP receptor are present at inflamed sites. CONCLUSION In a "proallergic" milieu, TSLP receptor is preferentially expressed on rare actively dividing T(H)2 cells. The direct action of TSLP on T cells could amplify T(H)2 responses at sites of allergic inflammation.
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Targeting allergen to Fc gammaRI: a strategy to treat allergic disease? Curr Opin Allergy Clin Immunol 2009; 8:547-52. [PMID: 18978470 DOI: 10.1097/aci.0b013e32831665d2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Targeting allergens to surface receptors on antigen presenting cells may provide a therapeutic strategy for allergic disease. This article discusses the immunomodulatory capacity of a molecule (H22-Fel d 1), which targets the major cat allergen, Fel d 1, to the high affinity IgG receptor, Fc gammaRI, on human dendritic cells. RECENT FINDINGS The fusion protein, H22-Fel d 1, induced a semi-mature phenotype in dendritic cells characterized by production of inflammatory cytokines with no change in surface markers, suggesting tolerogenic capacity. At the T-cell level, H22-Fel d 1 stimulated increased proliferation coupled with amplification of T cells expressing IL-5 and IL-10. Further analysis revealed induction of diverse T cell subtypes characteristic of Th0, regulatory Th1 and regulatory Th2 cells. Notably, this effect was restricted to T cells isolated from cat-allergic patients. Despite the increase in IL-5-expressing T cells, responses induced by H22-Fel d 1 appeared to be regulated by IL-10. Comparison with nonreceptor-targeted allergens from cat and house dust mite confirmed that qualitative T-cell changes induced by H22-Fel d 1 were unique. SUMMARY H22-Fel d 1 induces a novel variation of the Th2 response, which incorporates elements of a protective T-cell response. Exploiting Fc gammaRI-mediated pathways for allergen delivery may offer a new approach for treatment.
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Current World Literature. Curr Opin Allergy Clin Immunol 2008; 8:590-3. [DOI: 10.1097/aci.0b013e32831ceb82] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Hulse KE, Reefer AJ, Engelhard VH, Satinover SM, Patrie JT, Chapman MD, Woodfolk JA. Targeting Fel d 1 to FcgammaRI induces a novel variation of the T(H)2 response in subjects with cat allergy. J Allergy Clin Immunol 2007; 121:756-762.e4. [PMID: 18086491 DOI: 10.1016/j.jaci.2007.10.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 10/09/2007] [Accepted: 10/15/2007] [Indexed: 11/24/2022]
Abstract
BACKGROUND Induction of CD4+ T cells that produce IL-10 or IFN-gamma is central to the protective effects of conventional allergen immunotherapy. OBJECTIVE We examined the T-cell modulatory capacity of a fusion protein (H22-Fel d 1) that targets Fel d 1 to the high-affinity IgG receptor (FcgammaRI) on antigen-presenting cells. METHODS Monocyte-derived dendritic cells pulsed with H22-Fel d 1 were analyzed for surface phenotype and cytokine secretion by flow cytometry and cytometric bead assay, respectively. CD4+ T cells generated after coculture with H22-Fel d 1-pulsed dendritic cells were analyzed at the single-cell level by flow cytometry after intracellular cytokine staining. The T-cell repertoire was compared for subjects with (IgE+) and without cat allergy (IgE(neg)IgG(neg)), including subjects with a modified T(H)2 response (IgE(neg)IgG+). RESULTS H22-Fel d 1 induced a semimature phenotype in dendritic cells in conjunction with a selective increase in IL-5+ and IL-10+ CD4+ T cells compared with nonreceptor-targeted Fel d 1. Amplified T cells included diverse subtypes characteristic of T(H)0 (IL-5+IFN-gamma+), regulatory T(H)1 (IL-10+IFN-gamma+) and regulatory T(H)2 (IL-10+IL-5+ cells. T-cell qualitative changes were restricted to subjects with allergy and were distinct from a modified T(H)2 response. Blocking IL-10 induced by H22-Fel d 1 selectively increased IL-5+ CD4+ T cells, suggesting that T(H)2 responses were controlled. CONCLUSION Targeting Fel d 1 to FcgammaRI induces a novel variation of the T(H)2 response that incorporates major elements of a protective T-cell response.
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Affiliation(s)
- Kathryn E Hulse
- Asthma and Allergic Diseases Center, University of Virginia Health System, Charlottesville, VA 22908-1355, USA
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Reininger R, Varga EM, Zach M, Balic N, Lindemeier AD, Swoboda I, Grönlund H, van Hage M, Rumpold H, Valenta R, Spitzauer S. Detection of an allergen in dog dander that cross-reacts with the major cat allergen, Fel d 1. Clin Exp Allergy 2007; 37:116-24. [PMID: 17210049 DOI: 10.1111/j.1365-2222.2006.02611.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND A considerable proportion of animal-allergic patients are sensitized to both cat and dog allergens but knowledge about cross-reactive allergens in cat and dog dander is limited. OBJECTIVE To investigate whether dog dander contains an allergen that cross-reacts with the major cat allergen, Fel d 1. METHODS Recombinant Fel d 1 with the same immunological properties as natural Fel d 1 was used for quantitative (CAP) IgE competition experiments performed with sera obtained from cat-allergic patients (n=36). A Fel d 1 cross-reactive dog allergen was characterized by one- and two-dimensional immunoblotting using rFel d 1 for IgE inhibition experiments and with monospecific, polyclonal rabbit anti-recombinant Fel d 1 antibodies. RESULTS In 25% of Fel d 1-reactive cat-allergic patients, more than 50% inhibition of IgE reactivity to dog allergens was achieved with recombinant Fel d 1. An Fel d 1 cross-reactive 20 kDa allergen with a pI of approximately 3.4 was detected in dander extracts of several different dog breeds. CONCLUSION This is the first report demonstrating the presence of an Fel d 1-like allergen in dog dander extracts, which may be responsible for double positivity to cat and dog in serology. However, the clinical relevance of this cross-sensitization needs to be confirmed. These results are important for the diagnostic and therapeutic use of dog dander allergen extracts.
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Affiliation(s)
- R Reininger
- Clinical Institute for Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Vienna, Austria
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Kaiser L, Velickovic TC, Badia-Martinez D, Adedoyin J, Thunberg S, Hallén D, Berndt K, Grönlund H, Gafvelin G, van Hage M, Achour A. Structural characterization of the tetrameric form of the major cat allergen Fel d 1. J Mol Biol 2007; 370:714-27. [PMID: 17543334 DOI: 10.1016/j.jmb.2007.04.074] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 04/25/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
Felis domesticus allergen 1(Fel d 1) is a 35 kDa tetrameric glycoprotein formed by two heterodimers which elicits IgE responses in 95% of patients with allergy to cat. We have previously established in vitro conditions for the appropriate folding of recombinant Fel d 1 using a direct linkage of chain 1 to chain 2 (construct Fel d 1 (1+2)) and chain 2 to chain 1 (construct Fel d 1 (2+1)). Although the crystal structure of Fel d 1 (2+1) revealed a striking structural similarity to that of uteroglobin, a steroid-inducible cytokine-like molecule with anti-inflammatory and immunomodulatory properties, no functional tetrameric form of Fel d 1 could be identified. Here we present the crystal structure of the Fel d 1 (1+2) tetramer at 1.6 A resolution. Interestingly, the crystal structure of tetrameric Fel d 1 reveals two different calcium-binding sites. Symmetrically positioned on each side of the Fel d 1 tetramer, the external Ca(2+)-binding sites correspond to a putative Ca(2+)-binding site previously suggested for uteroglobin. The second Ca(2+)-binding site lies within the dimerization interface, stabilizing the formation of the Fel d 1 tetramer, and inducing important local conformational changes that directly govern the shape of two water-filled cavities. The crystal structure suggests a potential portal for an unknown ligand. Alternatively, the two cavities could be used by the allergen as a conditional inner space allowing for the spatial rearrangement of centrally localized side-chains, such as Asp130, without altering the overall fold of the molecule. The striking structural similarity of the major cat allergen to uteroglobin, coupled to the identification in the present study of a common Ca(2+)-binding site, let us speculate that Fel d 1 could provoke an allergic response through the modulation of phospholipase A2, by sequestering Ca ions in a similar manner as previously suggested for uteroglobin.
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Affiliation(s)
- Liselotte Kaiser
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
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T-cell responses to allergens. J Allergy Clin Immunol 2007; 119:280-94; quiz 295-6. [PMID: 17291848 DOI: 10.1016/j.jaci.2006.11.008] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 11/13/2006] [Accepted: 11/15/2006] [Indexed: 01/15/2023]
Abstract
The allergic response in human beings is engineered by CD4(+) T lymphocytes, which secrete T(H)2 cytokines in response to activation by allergen-derived peptides. Although T(H)2 cells have been well characterized, defining the properties of allergen-specific T cells has proved challenging in human beings because of their low frequency within the T-cell repertoire. However, recent studies have provided insight into the molecular signature of long-lived human memory T(H)2 cells, which are allergen-specific. T-cell responses directed against allergens develop in early life and are heavily influenced by the type and dose of allergen, and possibly coexposure to microbial products. These responses are susceptible to suppression by regulatory T cells. This article highlights recent advances in the characterization of allergen-specific memory T(H)2 cells and discusses the heterogeneous nature of regulatory T cells and possible mechanisms of action. The relevance of T-cell epitope mapping studies to understanding the unique nature of T-cell responses to different allergens, as well as to peptide vaccine development, is reviewed. Experimental techniques and approaches for analyzing allergen-specific T cells and identifying novel T-cell epitopes are described that may lead to new T-cell-based therapies.
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Peng Z, Xu W, Lam H, Cheng L, James AA, Simons FER. A new recombinant mosquito salivary allergen, rAed a 2: allergenicity, clinical relevance, and cross-reactivity. Allergy 2006; 61:485-90. [PMID: 16512811 DOI: 10.1111/j.1398-9995.2006.00985.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mosquito salivary proteins cause allergic reactions in humans. The allergenicity, clinical relevance, and species cross-reactivity of a new 37-kDa recombinant mosquito (Aedes aegypti) salivary allergen, rAed a 2, were evaluated. METHODS rAed a 2 was expressed using a baculovirus/insect cell system and purified. Its allergenicity was examined using an enzyme-linked immunosorbent assay (ELISA), ELISA inhibition tests, immunoblots, and skin tests. Epicutaneous tests with the allergen, mosquito whole body extracts, and mosquito bite tests were performed on 48 volunteers. Serum rAed a 2-specific immunoglobulin E (IgE) was measured in individuals with positive mosquito saliva-specific IgE and negative controls. RESULTS Both immunoblots and ELISAs demonstrated that rAed a 2 bound to the IgE of mosquito-allergic individuals. The binding could be inhibited by the addition of a natural mosquito preparation. Furthermore, rAed a 2 induced immediate and delayed skin reactions. Ten per cent of 31 participants with a positive mosquito bite test had positive skin reactions to rAed a 2, compared with 32% for mosquito whole body extract. None of the participants with a negative bite test showed positive reactions to either of the two extracts. Forty-three per cent of individuals with positive saliva-IgE had positive rAed a 2-IgE. rAed a 2 was a species-shared allergen, being present in the saliva of the 11 species studied. CONCLUSIONS rAed a 2 has identical antigenicity and biologic activity to its native form. It can be used in the diagnosis of mosquito allergy, and is an important species-shared antigen.
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Affiliation(s)
- Z Peng
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada
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16
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Abstract
The application of recombinant DNA technology to allergen research has provided the sequence information and genetic material to produce new types of allergy vaccines. One general strategy has been to use the knowledge to produce synthetic peptides that represent selected T-cell or B-cell epitopes. The production of genetically engineered allergens provides an alternative strategy to construct hypoallergenic vaccines, which can provide a better and less selected representation of the epitopes. Many strategies have been used to produce such hypoallergens, and their ability to reduce allergenicity has been amply demonstrated by skin and nasal provocation tests. The retention of T cell-stimulating activity has also been demonstrated, and a consistent feature of the vaccines has been, despite the reduced immunoglobulin E (IgE)-binding reactivity, the ability to induce anti-allergen IgG antibody. The lead hypoallergens have been polypeptide fragments and trimeric constructs of the birch allergen Bet v 1. A clinical trial with these medicaments has shown the ability to modify IgE and IgG antibody production, skin test reactivity, and symptom scores. This is the first trial of a recombinant allergy vaccine, and it has set a benchmark for further studies. A new generation of hypoallergens is now being produced based on the detailed knowledge of the tertiary structures of the allergens and of the T-cell and B-cell epitopes. The modifications have been made to change the topography of the allergens while retaining a stable, folding structure. In the case of Bet v 1, tertiary structures of hypoallergens have been determined. Structurally modeled hypoallergens have been produced for pollen, venom, food, and latex allergens, with promising characteristics from preclinical studies.
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Affiliation(s)
- Wayne R Thomas
- Centre for Child Health Research, University of Western Australia, Telethon Institute for Child Health Research, PO Box 855, West Perth 6872, 100 Roberts Road, Subiaco 6008, Western Australia.
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Barral P, Serrano AG, Batanero E, Pérez-Gil J, Villalba M, Rodríguez R. A recombinant functional variant of the olive pollen allergen Ole e 10 expressed in baculovirus system. J Biotechnol 2005; 121:402-9. [PMID: 16168508 DOI: 10.1016/j.jbiotec.2005.07.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 07/08/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
Pollens have been reported as important sources of antigens causing type-I allergy and, among them, olive pollen has high clinical relevance in Mediterranean countries. The most recently described olive allergen, Ole e 10, is involved in cross-reactivity phenomena and related to asthma induction in allergic patients. These immunologic features make this allergen a good candidate to be included in diagnosis and therapy of protocols of allergic diseases. Since the availability of Ole e 10 from the olive pollen is limited, the allergen has been efficiently expressed in the baculovirus/insect cell system. The Ole e 10-cDNA inserted into the transfer vector pBacPAK8 allowed the expression of the recombinant protein in cultured Sf21 cells. Recombinant Ole e 10 (rOle e 10) was purified from the culture after dialysis and three chromatographic steps. Mass spectrometry, Edman degradation, IgE- and IgG-binding analyses were employed to characterize the recombinant allergen, which showed molecular and immunological equivalence with the natural protein. Affinity gel electrophoresis in presence of laminarin (1,3-beta-glucan) revealed that rOle e 10 retains identical carbohydrate-binding capacity than the natural allergen. In conclusion, the recombinant expression of Ole e 10 in baculovirus/insect cell system produces a homogeneous and biologically active allergen that could be useful for clinical and scientific purposes.
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Affiliation(s)
- Patricia Barral
- Departamento de Bioquímica y Biología Molecular I, Facultad de Químicas, Universidad Complutense, 28040 Madrid, Spain
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Zhu D, Kepley CL, Zhang K, Terada T, Yamada T, Saxon A. A chimeric human-cat fusion protein blocks cat-induced allergy. Nat Med 2005; 11:446-9. [PMID: 15793580 DOI: 10.1038/nm1219] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Accepted: 03/03/2005] [Indexed: 11/09/2022]
Abstract
Animal allergens are an important cause of asthma and allergic rhinitis. We designed and tested a chimeric human-cat fusion protein composed of a truncated human IgG Fcgamma1 and the major cat allergen Fel d1, as a proof of concept for a new approach to allergy immunotherapy. This Fcgamma-Fel d1 protein induced dose-dependent inhibition of Fel d1-driven IgE-mediated histamine release from cat-allergic donors' basophils and sensitized human cord blood-derived mast cells. Such inhibition was associated with altered Syk and ERK signaling. The Fcgamma-Fel d1 protein also blocked in vivo reactivity in FcepsilonRIalpha transgenic mice passively sensitized with human IgE antibody to cat and in Balb/c mice actively sensitized against Fel d1. The Fcgamma-Fel d1 protein alone did not induce mediator release. Chimeric human Fcgamma-allergen fusion proteins may provide a new therapeutic platform for the immune-based therapy of allergic disease.
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Affiliation(s)
- Daocheng Zhu
- The Hart and Louise Lyon Laboratory, Division of Clinical Immunology/Allergy, Department of Medicine, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, California 90095-1680, USA.
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19
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Seppälä U, Hägglund P, Wurtzen PA, Ipsen H, Thorsted P, Lenhard T, Roepstorff P, Spangfort MD. Molecular characterization of major cat allergen Fel d 1: expression of heterodimer by use of a baculovirus expression system. J Biol Chem 2004; 280:3208-16. [PMID: 15546862 DOI: 10.1074/jbc.m410668200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fel d 1 is a major cat allergen inducing allergic rhinitis and asthma in sensitized individuals. It has a more complex structure when compared with other allergens and therefore expression of recombinant Fel d 1 has been considered a challenge. The present study shows for the first time that a Baculovirus expression system is able to produce an intact rFel d 1 molecule that is glycosylated and structurally equivalent to the natural cat allergen, nFel d 1. Enzymatic digestion of rFel d 1 and further analysis by use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) resulted in a complete coverage of the amino acid sequence of rFel d 1. In addition, the three disulfide bridges at the positions alpha70-beta7, alpha44-beta48, and alpha3-beta73 were verified. The N-glycan structure of rFel d 1 was investigated by a combination of MALDI-TOF MS and monosaccharide analysis by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAC). The N-glycosylation analyses of rFel d 1 refer to a pattern of glycoforms including core alpha1.3-fucosylation that is different from nFel d 1. Further characterization by use of human serum IgE, histamine release, and lymphocyte proliferation assays demonstrated that the immunological characteristics of rFel d 1 are similar to those of nFel d 1. Detailed characterization of both natural and recombinant allergens provides tools to explore immunological mechanisms associated with allergen sensitization and desensitization.
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Affiliation(s)
- Ulla Seppälä
- Department of Vaccine Research, ALK-Abelló, 2970 Hørsholm, Denmark
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20
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Tao AL, He SH. Bridging PCR and partially overlapping primers for novel allergen gene cloning and expression insert decoration. World J Gastroenterol 2004; 10:2103-8. [PMID: 15237444 PMCID: PMC4572343 DOI: 10.3748/wjg.v10.i14.2103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To obtain the entire gene open reading frame (ORF) and to construct the expression vectors for recombinant allergen production.
METHODS: Gene fragments corresponding to the gene specific region and the cDNA ends of pollen allergens of short ragweed (Rg, Ambrosia artemisiifolia L.) were obtained by pan-degenerate primer-based PCR and rapid amplification of the cDNA ends (RACE), and the products were mixed to serve as the bridging PCR (BPCR) template. The full-length gene was then obtained. Partially overlapping primer-based PCR (POP-PCR) method was developed to overcome the other problem, i.e., the non-specific amplification of the ORF with routine long primers for expression insert decoration. Northern blot was conducted to confirm pollen sources of the gene. The full-length coding region was evaluated for its gene function by homologue search in GenBank database and Western blotting of the recombinant protein Amb a 8 (D106) expressed in Escherichia coli pET-44 system.
RESULTS: The full-length cDNA sequence of Amb a 8(D106) was obtained by using the above procedure and deduced to encode a 131 amino acid polypeptide. Multiple sequence alignment exhibited the gene D106 sharing a homology as high as 54%-89% and 79%-89% to profilin from pollen and food sources, respectively. The expression vector of the allergen gene D106 was successfully constructed by employing the combined method of BPCR and POP-PCR. Recombinant allergen rAmb a 8(D106) was then successfully generated. The allergenicity was hallmarked by immunoblotting with the allergic serum samples and its RNA source was confirmed by Northern blot.
CONCLUSION: The combined procedure of POP-PCR and BPCR is a powerful method for full-length allergen gene retrieval and expression insert decoration, which would be useful for recombinant allergen production and subsequent diagnosis and immunotherapy of pollen and food allergy.
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Affiliation(s)
- Ai-Lin Tao
- Allergy and Inflammation Research Institute, Medical College, Shantou University, 22 Xin-Ling Road, Shantou 515031, Guangdong Province, China
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Peng Z, Simons FER. Mosquito Allergy: Immune Mechanisms and Recombinant Salivary Allergens. Int Arch Allergy Immunol 2004; 133:198-209. [PMID: 14963366 DOI: 10.1159/000076787] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Reactions to mosquito bites are immunological in nature, with the involvement of IgE-, IgG- and T lymphocyte-mediated hypersensitivities. Acquired desensitization to mosquito saliva may occur during childhood and adolescence or during long-term exposure to mosquito bites. Due to the lack of salivary preparations, allergic reactions to mosquito bites are underdiagnosed and undertreated. Recombinant mosquito saliva allergens with biological activity are being developed. These recombinant allergens will significantly improve diagnosis of mosquito allergy and eventually will also improve specific immunotherapy for patients with systemic reactions to mosquito bites.
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Affiliation(s)
- Zhikang Peng
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Canada.
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Liccardi G, D'Amato G, Russo M, Canonica GW, D'Amato L, De Martino M, Passalacqua G. Focus on cat allergen (Fel d 1): immunological and aerodynamic characteristics, modality of airway sensitization and avoidance strategies. Int Arch Allergy Immunol 2003; 132:1-12. [PMID: 14555853 DOI: 10.1159/000073259] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The increasing frequency of pet ownership (especially cats) in many industrialized countries has raised the level of exposure to the allergens produced by these animals. Moreover, it is likely that modern energy-saving systems and the wide use of upholstered furniture has resulted in closer contact between cats (and their allergens) and humans. Many different methods have been developed to quantify the main cat allergen (Fel d 1) in settled dust and in ambient air. The threshold levels of cat allergen inducing sensitization or triggering respiratory symptoms in sensitized patients have been calculated in settled dust, but airborne amounts of Fel d 1 probably represent a more reliable index of allergen exposure. Noticeably, the amount of Fel d 1 may be relatively high also in confined environments where cats have never been kept. It has been demonstrated that clothes of cat owners are the main source for dispersal of allergens in cat-free environments. This fact may be of relevance, because recent studies have shown that allergic sensitization to cats is more likely to develop in children exposed to moderate levels of this allergen than in children exposed to high amounts of Fel d 1. The ubiquity of cat allergen may justify the common observation that allergen avoidance is often insufficient to reduce the risk of developing allergic sensitization and/or symptom exacerbation in highly susceptible patients. Further efforts are needed to improve the efficacy of Fel d 1 avoidance strategies to try to reduce the risk of allergic sensitization to this allergen.
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Affiliation(s)
- Gennaro Liccardi
- Department of Chest Diseases, Division of Pneumology and Allergology, High Speciality Hospital A. Cardarelli, Naples, Italy
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Grönlund H, Bergman T, Sandström K, Alvelius G, Reininger R, Verdino P, Hauswirth A, Liderot K, Valent P, Spitzauer S, Keller W, Valenta R, van Hage-Hamsten M. Formation of disulfide bonds and homodimers of the major cat allergen Fel d 1 equivalent to the natural allergen by expression in Escherichia coli. J Biol Chem 2003; 278:40144-51. [PMID: 12732623 DOI: 10.1074/jbc.m301416200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Dander from the domestic cat (Felis domesticus) is one of the most common causes of IgE-mediated allergy. Attempts to produce tetrameric folded major allergen Fel d 1 by recombinant methods with structural features similar to the natural allergen have been only partially successful. In this study, a recombinant folded Fel d 1 with molecular and biological properties similar to the natural counterpart was produced. A synthetic gene coding for direct fusion of the Fel d 1 chain 2 N-terminally to chain 1 was constructed by overlapping oligonucleotides in PCR. Escherichia coli expression resulted in a non-covalently associated homodimer with an apparent molecular mass of 30 kDa defined by size exclusion chromatography. Furthermore, each 19,177-Da subunit displayed a disulfide pattern identical to that found in the natural Fel d 1, i.e. Cys3(1) Cys73(2), Cys44(1)-Cys48(2), Cys70(1)-Cys7(2), as determined by electrospray mass spectrometry after tryptic digestion. Circular dichroism analysis showed identical folds of natural and recombinant Fel d 1. Furthermore, recombinant Fel d l reacted specifically with serum IgE, inducing expression of CD203c on basophils and lymphoproliferative responses in cat-allergic patients. The results show that the overall fold and immunological properties of the recombinant Fel d 1 are very similar to those of natural Fel d 1. Moreover, the recombinant Fel d 1 construct provides a tool for defining the three-dimensional structure of Fel d 1 and represents a reagent for diagnosis and allergen-specific immunotherapy of cat allergy.
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Affiliation(s)
- Hans Grönlund
- Unit of Clinical Immunology and Allergy, Karolinska Institutet, Stockholm, Sweden.
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Matsui E, Kagey-Sobotka A, Chichester K, Eggleston PA. Allergic potency of recombinant Fel d 1 is reduced by low concentrations of chlorine bleach. J Allergy Clin Immunol 2003; 111:396-401. [PMID: 12589362 DOI: 10.1067/mai.2003.11] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Sodium hypochlorite (NaOCl), the primary component of household bleach, has been shown to alter the purified mouse allergen Mus m 1, such that antibody recognition, or immunogenicity, is lost. Results of initial experiments suggest that antibody recognition is lost at lower concentrations of NaOCl than those required to fragment Mus m 1. OBJECTIVE We sought to determine whether NaOCl had similar effects on recombinant (r)Fel d 1 and whether the loss of antibody recognition correlated with the loss of biologic activity, as measured with a basophil histamine release assay. METHODS Recombinant Fel d 1 was treated with increasing amounts of NaOCl, and the product of the reaction was analyzed by using SDS-PAGE, Western blotting, and ELISA. The biologic activity of NaOCl-treated rFel d 1 was analyzed with a basophil histamine release assay. RESULTS The protein fragmented at an NaOCl/rFel d 1 molar ratio of 7000, whereas cat-specific IgG recognition was lost at a lower molar ratio of 560. Basophil histamine release assays were performed to determine the effect of NaOCl on the biologic activity of rFel d 1. An NaOCl/protein molar ratio of 70 caused a significant reduction in histamine release from basophils of subjects with cat allergy. A molar ratio of 140 further inhibited histamine release by rFel d 1, suggesting a dose-response relationship between NaOCl and loss of biologic activity. CONCLUSIONS NaOCl modifies rFel d 1, resulting in loss of immunogenicity and attenuation of biologic activity, as measured by its ability to stimulate basophil histamine release.
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Affiliation(s)
- Elizabeth Matsui
- Departments of Pediatrics and Medicine, Johns Hopkins School of Medicine, Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287, USA
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