Cloning and expression of cDNA coding for a new allergen from the house dust mite, Dermatophagoides farinae: homology with human heat shock cognate proteins in the heat shock protein 70 family

Exosomes Derived from Dermatophagoides farinae Induce Allergic Airway Inflammation

House dust mites (HDMs) are a major source of indoor allergens that cause airway allergic disease. Dermatophagoides farinae, a predominant species of HDMs in China, has demonstrated pathogenic role in allergic disorders. Exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. Here, D. farinae was stirred overnight in phosphate-buffered saline, and the supernatant was used to extract exosomes by ultracentrifugation. Then, shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing were performed to identify proteins and microRNAs contained in D. farinae exosomes. Immunoblotting, Western blotting, and enzyme-linked immunosorbent assay demonstrated the specific immunoreactivity of D. farinae-specific serum IgE antibody against D. farinae exosomes, and D. farinae exosomes were found to induce allergic airway inflammation in a mouse model. In addition, D. farinae exosomes invaded 16-HBE bronchial epithelial cells and NR8383 alveolar macrophages to release the inflammation-related cytokines interleukin-33 (IL-33), thymic stromal lymphopoietin, tumor necrosis factor alpha, and IL-6, and comparative transcriptomic analysis of 16-HBE and NR8383 cells revealed that immune pathways and immune cytokines/chemokines were involved in the sensitization of D. farinae exosomes. Taken together, our data demonstrate that D. farinae exosomes are immunogenic and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. IMPORTANCE Dermatophagoides farinae, a predominant species of house dust mites in China, has displayed pathogenic role in allergic disorders, and exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. This study, for the first time, extracted exosomes from D. farinae, and sequenced their protein cargo and microRNAs using shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing. D. farinae-derived exosomes trigger allergen-specific immune responses and present satisfactory immunogenicity, as revealed by immunoblotting, Western blotting, and enzyme-linked immunosorbent assay and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. Our data provide insights into the mechanisms of allergic airway inflammation caused with D. farinae-derived exosomes and the treatment of house dust mite-induced allergic airway inflammation.

RNA viruses alter house dust mite physiology and allergen production with no detected consequences for allergenicity

RNA viruses have recently been detected in association with house dust mites, including laboratory cultures, dust samples, and mite-derived pharmaceuticals used for allergy diagnosis. This study aimed to assess the incidence of viral infection on Dermatophagoides pteronyssinus physiology and on the allergenic performance of extracts derived from its culture. Transcriptional changes between genetically identical control and virus-infected mite colonies were analysed by RNAseq with the support of a new D. pteronyssinus high-quality annotated genome (56.8 Mb, 108 scaffolds, N50 = 2.73 Mb, 96.7% BUSCO-completeness). Extracts of cultures and bodies from both colonies were compared by inspecting major allergen accumulation by enzyme-linked immunosorbent assay (ELISA), allergen-related enzymatic activities by specific assays, airway inflammation in a mouse model of allergic asthma, and binding to allergic patient's sera IgE by ImmunoCAP. Viral infection induced a significant transcriptional response, including several immunity and stress-response genes, and affected the expression of seven allergens, putative isoallergens and allergen orthologs. Major allergens were unaffected except for Der p 23 that was upregulated, increasing ELISA titers up to 29% in infected-mite extracts. By contrast, serine protease allergens Der p 3, 6 and 9 were downregulated, being trypsin and chymotrypsin enzymatic activities reduced up to 21% in extracts. None of the parameters analysed in our mouse model, nor binding to human IgE were significantly different when comparing control and infected-mite extracts. Despite the described physiological impact of viral infection on the mites, no significant consequences for the allergenicity of derived extracts or their practical use in allergy diagnosis have been detected.

Heat shock cognate 70 protein like-2 protein in camphor pollen is one of the major culprits of asthma

AIMS

In recent decades, Cinnamomum camphora have gradually become the main street trees in Shanghai. This study aims to investigate the allergenicity of camphor pollen.

MAIN METHODS

A total of 194 serum samples from patients with respiratory allergy were collected and analyzed. Through protein profile identification and bioinformatics analysis, we hypothesized that heat shock cognate protein 2-like protein (HSC70L2) is the major potential allergenic protein in camphor pollen. Recombinant HSC70L2 (rHSC70L2) was expressed and purified, and a mouse model of camphor pollen allergy was established by subcutaneous injection of total camphor pollen protein extract (CPPE) and rHSC70L2.

KEY FINDINGS

Specific IgE was found in the serum of 5 patients in response to camphor pollen and three positive bands were identified by Western blotting. Enzyme-linked immunosorbent assay (ELISA), Immune dot blot and Western blot experiments confirmed that CPPE and rHSC70L2 can cause allergies in mice. Moreover, rHSC70L2 induces polarization of peripheral blood CD4⁺ T cells to Th2 cells in patients with respiratory allergies and mice with camphor pollen allergy. Finally, we predicted the T cell epitope of the HSC70L2 protein, and through the mouse spleen T cell stimulation experiment, we found that the ²⁹⁵EGIDFYSTITRARFE³⁰⁹ peptide induced T cells differentiation to Th2 and macrophages differentiation to the alternatively activated (M2) state. Moreover, ²⁹⁵EGIDFYSTITRARFE³⁰⁹ peptide increased the serum IgE levels in mice.

SIGNIFICANCE

The identification of HSC70L2 protein can provide novel diagnostic and therapeutic targets for allergies caused by camphor pollen.

Proteomic Profiling Reveals New Insights into the Allergomes of Anisakis simplex, Pseudoterranova decipiens, and Contracaecum osculatum

Anisakis simplex, Pseudoterranova decipiens, and Contracaecum osculatum third-stage larvae (L3) are fish-borne nematodes that can cause human anisakidosis. Although A. simplex is a known source of allergens, knowledge about the allergic potential of P. decipiens and C. osculatum is limited. Therefore, we performed comparative proteomic profiling of A. simplex, P. decipiens, and C. osculatum L3 larvae using liquid chromatography-tandem mass spectrometry. In total, 645, 397, and 261 proteins were detected in A. simplex, P. decipiens, and C. osculatum L3 larvae, respectively. Western blot analysis confirmed the cross-reactivity of anti-A. simplex immunoglobulin (Ig)G antibodies with protein extracts from P. decipiens and C. osculatum L3 larvae. The identified proteins of the Anisakidae proteomes were characterized by label-free quantification and functional analysis, and proteins involved in many essential biological mechanisms, such as parasite survival, were identified. In the proteome of A. simplex 14, the following allergens were identified: Ani s 1, Ani s 2 (2 isomers), Ani s 3 (2 isomers), Ani s 4, Ani s 8, Ani s 9, Ani s 10, Ani s 11-like, Ani s 13, Ani s fructose 1,6-bisphosphatase, Ani s phosphatidylethanolamine-binding protein (PEPB), and Thu a 3.0101. The following 8 allergens were detected in P. decipiens: Ani s 2, Ani s 3 (2 isomers), Ani s 5, Ani s 8, Ani s 9, Ani s PEPB, and Ani s troponin. In C. osculatum 4, the following allergens were identified: Ani s 2, Ani s 5, Ani s 13, and Asc l 3. Furthermore, 28 probable allergens were predicted in A. simplex and P. decipiens, whereas in C. osculatum, 25 possible allergens were identified. Among the putative allergens, heat shock proteins were most frequently detected, followed by paramyosin, peptidyl-prolyl cis-trans isomerase, enolase, and tropomyosin. We provide a new proteomic data set that could be beneficial for the discovery of biomarkers or drug target candidates. Furthermore, our findings showed that in addition to A. simplex, P. decipiens and C. osculatum should also be considered as potential sources of allergens that could lead to IgE-mediated hypersensitivity.

The Role of Heat Shock Protein 70 kDa in Asthma

Asthma is a complex chronic disorder of the airways, affecting immune and structural cells and inducing both protein and tissue remodeling. Heat shock proteins 70 kDa (HSP70s) are highly conserved members of the stress-induced family, possessing precisely described chaperone activity. There is growing evidence of a tight relationship between inflammatory diseases of different origins and the elevation of local HSP70 expression and secretion. Although extracellular HSP70 does not serve as a common marker of asthma, elevated HSP70 levels have been detected in the peripheral blood serum and sputum of patients with asthma, as well as in the bronchoalveolar lavage fluid of mice with induced allergic airway inflammation. Possessing diverse immunomodulating properties, extracellular HSP70 can manifest different activities in airway inflammatory processes and asthma, acting either as a pro-inflammatory trigger, or an anti-inflammatory agent. This review will discuss the effects and possible mechanisms concerning HSP70 implication in airway inflammation regulation in asthma. We examine ATPase and chaperone activities of HSP70 as potential modulators of immune responses in asthma. Given the crucial role of a chronic inflammatory response in asthma, understanding the effects of HSP70 on immune and structural cells may reveal new perspectives for the therapeutic control of inflammation.

Proteomic and Bioinformatic Investigations of Heat-Treated Anisakis simplex Third-Stage Larvae

Anisakis simplex third-stage larvae are the main source of hidden allergens in marine fish products. Some Anisakis allergens are thermostable and, even highly processed, could cause hypersensitivity reactions. However, Anisakis proteome has not been studied under autoclaving conditions of 121 °C for 60 min, which is an important process in the food industry. The aim of the study was the identification and characterization of allergens, potential allergens, and other proteins of heat-treated A. simplex larvae. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify 470 proteins, including allergens-Ani s 1, Ani s 2, Ani s 3, Ani s 4, Ani s 5-and 13 potential allergens that were mainly homologs of Anisakis spp., Ascaris spp., and Acari allergens. Ani s 2, Ani s 3, Ani s 5, and three possible allergens were found among the top 25 most abundant proteins. The computational analysis allowed us to detect allergen epitopes, assign protein families, and domains as well as to annotate the localization of proteins. The predicted 3D models of proteins revealed similarities between potential allergens and homologous allergens. Despite the partial degradation of heated A. simplex antigens, their immunoreactivity with anti-A. simplex IgG antibodies was confirmed using a Western blot. In conclusion, identified epitopes of allergenic peptides highlighted that the occurrence of Anisakis proteins in thermally processed fish products could be a potential allergic hazard. Further studies are necessary to confirm the IgE immunoreactivity and thermostability of identified proteins.

Heat Shock Protein 60: Identification of an Undetected Allergen from Dermatophagoides farinae

Background

Recently, the incidence of allergic diseases has been on the rise; Dust mite is the major indoor allergen which needs a special consideration.

Objectives

This study was carried out to identify and investigate the molecular properties of a new allergen named Hsp60 and to afford a foundation for future research of the allergic diseases caused by Dermatophagoides farinae.

Materials and Methods

Using polymerase chain reaction (PCR) with degenerate primer, the cDNA of Dermatophagoides farinae Hsp60 was amplified and sequenced. Next, the cDNA fragment was cloned into the prokaryotic expression vector pET-32a for the expression of the Hsp60. Then, it was further characterized by Elisa and Western Blot analysis.

Results

The partial cDNA sequence of the Dermatophagoides farinae Hsp60 was determined, and the recombinant Hsp60 was successfully expressed in Escherichia coli BL21. ELISA and Western blot analysis showed that the recombinant protein could be specifically recognized by SIgE from sera of the Dermatophagoides farina-allergic patients.

Conclusions

Our group has, for the first time, demonstrated the fact that there is an Hsp60 family of Dermatophagoides farinae and analyzed the allergenicity of the Hsp60 with immunological method. These results provide a foundation for further allergological research of the Dermatophagoides farinae Hsp60.

House Dust Mite Allergens: New Discoveries and Relevance to the Allergic Patient

PURPOSE OF REVIEW

Recent findings on house dust allergens and their contribution to knowledge that will significantly impact on current and future allergy treatments are appraised.

RECENT FINDINGS

Quantitation of IgE binding to a spectrum of allergen components in several independent studies in varying locations has largely affirmed the main components as the groups 1 and 2 and possibly 23 allergens with mid-tier contributions from the groups 4, 5, 7, and 21. Prevalent binding to Der p 23 has been recapitulated sometimes with low titers. The IgE of non-asthmatic atopic subjects binds at lower titer and to fewer components than that of asthmatics, and their IgG binding relative to IgE is higher especially for children hospitalized for exacerbation. The higher IgG ratios were associated with increased IL-10 a cytokine more readily induced from T cells of allergic subjects. Peptides representing the groups 1 and 2 allergens can be used to stimulate ex vivo T cells showing responses correlating with IgE binding and providing a valuable tool for ascertaining the contribution of IgE and T cells to disease. Also, the induction of Th2 and follicular helper T cells are shown to make different contributions in mice. Cross-reactivity of IgE binding assays with high-titer cross-reactive antibodies induced by scabies is a problem in the many areas of the world where scabies is highly prevalent and endemic and from recent increases in immigration. In the last few years, allergen research has produced results that warrant rapid translation into diagnostic tools and the formulation of allergen components for immunotherapy.

Transcriptomic/proteomic identification of allergens in the mite Tyrophagus putrescentiae

While a number of allergens from house dust mites have been described, much remains to be discovered about allergens from storage mites. Here, next-generation sequencing was combined with MS/MS shotgun proteomics to identify proteins, especially potential allergens from Tyrophagus putrescentiae, commonly found in stored food products, especially flour. cDNAs of suspected allergens were cloned and expressed from bacterial cells, and recombinant allergens were tested for binding to IgE in sera from T. putrescentiae-sensitive patients. These analyses identified three previously uncharacterized allergens, Tyr p 28, Tyr p 35, and Tyr p 36, which have been officially assigned by the WHO/IUIS Allergen Nomenclature Sub-committee. Recombinant proteins rTyr p 28, rTyr p 35, and rTyr p 36 bound with 47.1%, 82.4%, and 70.6% of T. putrescentiae-sensitive sera. We provide here a new method to identify allergens by the combination of transcriptomic and proteomic approaches.

Der f 34, a Novel Major House Dust Mite Allergen Belonging to a Highly Conserved Rid/YjgF/YER057c/UK114 Family of Imine Deaminases

The high prevalence of house dust mite (HDM) allergy is a growing health problem worldwide, and the characterization of clinically important HDM allergens is a prerequisite for the development of diagnostic and therapeutic strategies. Here, we report a novel HDM allergen that belongs structurally to the highly conserved Rid/YjgF/YER057c/UK114 family (Rid family) with imine deaminase activity. Isolated HDM cDNA, named der f 34, encodes 128 amino acids homologous to Rid-like proteins. This new protein belongs to the Rid family and has seven conserved residues involved in enamine/imine deaminase activity. Indeed, we demonstrated that purified Der f 34 had imine deaminase activity that preferentially acted on leucine and methionine. Native Der f 34 showed a high IgE binding frequency as revealed by two-dimensional immunoblotting (62.5%) or ELISA (68%), which was comparable with those of a major HDM allergen Der f 2 (77.5 and 79%, respectively). We also found that Der f 34 showed cross-reactivity with another prominent indoor allergen source, Aspergillus fumigatus This is the first report showing that the Rid family imine deaminase represents an additional important pan-allergen that is conserved across organisms.

Characterization of a new subtype of allergen in dermatophagoides farinae-Der f 28

BACKGROUND

House dust mites (HDMs) are the major sources of indoor allergens which induce asthma, dermatitis, rhinitis, and some other allergic diseases. Close to 30 sub-allergens have been identified.

METHODS

Through analyzing the full genome sequence of dust mite, a new allergen whose primary structure belongs to the heat shock protein family was identified. The sequence of this allergen was determined by cDNA cloning. The allergenicity was assayed by skin prick test, Western-blot and enzyme-linked immunosorbent assay (ELISA).

RESULTS

r-Der f 28 bound to serum IgE from mite allergic patients. Positive responses to r-Der f 28 were shown in 11.5% by skin prick testing from 26 DM-allergic patients. Airway hyperresponsiveness, serum specific IgE and IL-4 were significantly increased in allergic asthma mouse model sensitized to r-Der f 28.

CONCLUSIONS

Der f 28 is a new subtype of allergen in dermatophagoides farinae.

Auto-induction for high yield expression of recombinant novel isoallergen tropomyosin from King prawn (Melicertus latisulcatus) for improved diagnostics and immunotherapeutics

Food allergies are increasing worldwide, demonstrating a considerable public health concern. Shellfish allergy is one of the major food groups causing allergic sensitization among adults and children, affecting up to 2% of the general world population. Tropomyosin (TM) is the major allergen in shellfish and frequently used in the diagnosis of allergic sensitization and the detection of cross-contaminated food. To improve and establish better and more sensitive diagnostics for allergies and immunotherapeutics, large quantities of pure allergens are required. To establish a reproducible method for the generation of pure recombinant tropomyosin we utilized in this study different Escherichia coli strains (NM522, TOP10 and BL21(DE3)RIPL). In addition, isopropyl-β-D-thiogalactoside (IPTG) induction was compared with a novel auto-induction system to allow the generation of larger quantities of recombinant allergen. We demonstrated that the B-strain of E. coli is better for the expression of TM compared to the K-strain. Moreover, a higher yield could be achieved when using the auto-induction system, with up to 62 mg/l. High yield expressed recombinant TM from King prawn (KP) was compared to recombinant TM from Black tiger prawn (Pen m 1). We demonstrated that recombinant TM from KP and known isoallergen Pen m 1 have very similar molecular and immunological characteristics. Overall, we demonstrate that auto-induction can be used to express larger quantities of recombinant allergens for the development of diagnostic, to quantify allergens as well as immunotherapeutics employing isoallergens.

Characterisation of potential novel allergens in the fish parasite Anisakis simplex

The parasitic nematode Anisakis simplex occurs in fish stocks in temperate seas. A. simplex contamination of fish products is unsavoury and a health concern considering human infection with live larvae (anisakiasis) and allergic reactions to anisakid proteins in seafood. Protein extracts of A. simplex produce complex band patterns in gel electrophoresis and IgE-immunostaining. In the present study potential allergens have been characterised using sera from A. simplex-sensitised patients and proteome data obtained by mass spectrometry. A. simplex proteins were homologous to allergens in other nematodes, insects, and shellfish indicating cross-reactivity. Characteristic marker peptides for relevant A. simplex proteins were described.

Proteome and allergenome of Asian wasp, Vespa affinis, venom and IgE reactivity of the venom components

Vespa affinis (Asian wasp, Thai banded tiger wasp, or local name: Tor Hua Seua) causes the most frequent incidence of medically important Hymenoptera sting in South and Southeast Asia. However, data on the venom components attributable to the sting derived-clinical manifestations (local reactions, IgE mediated-anaphylaxis, or systemic envenomation) are lacking. This study provides the first set information on V. affinis venom proteome, allergenome, and IgE reactivity of individual venom components. From 2DE-gel based-proteomics, the venom revealed 93 protein spots, of which proteins in 51 spots could be identified and classified into three groups: typical venom components and structural and housekeeping proteins. Venom proteins in 32 spots reacted with serum IgE of wasp allergic patients. Major allergenic proteins that reacted to IgE of >50% of the wasp allergic patients included PLA1 (100%), arginine kinase (73%), heat shock 70 kDa protein (73.3%), venom allergen-5 (66.7%), enolase (66.7%), PLA1 magnifin (60%), glyceraldehyde-3-phosphate dehydrogenase (60%), hyaluronidase (53.3%), and fructose-bisphosphate aldolase (53.3%). The venom minor allergens were GB17876 transcript (40%), GB17291 transcript (20%), malic enzyme (13.3%), aconitate hydratase (6.7%), and phosphoglucomutase (6.7%). The information has diagnostic and clinical implications for future improvement of case diagnostic sensitivity and specificity, component-resolve diagnosis, and design of specific Hymenoptera venom immunotherapy.

House dust mite allergy in Korea: the most important inhalant allergen in current and future

The house-dust mite (HDM), commonly found in human dwellings, is an important source of inhalant and contact allergens. In this report, the importance of HDM allergy in Korea and the characteristics of allergens from dust mite are reviewed with an emphasis on investigations performed in Korea. In Korea, Dermatophagoides farinae is the dominant species of HDM, followed by D. pteronyssinus. Tyrophagus putrescentiae is also found in Korea, but its role in respiratory allergic disease in Korea is controversial. The relatively low densities of mite populations and concentrations of mite major allergens in dust samples from Korean homes, compared to westernized countries, are thought to reflect not only different climatic conditions, but also cultural differences, such as the use of 'ondol' under-floor heating systems in Korean houses. HDM are found in more than 90% of Korean houses, and the level of exposure to HDM is clinically significant. About 40%-60% of Korean patients suffering from respiratory allergies, and more than 40% of patients suffering from atopic dermatitis, are sensitized to HDM. Mite allergens can be summarized according to their inherent auto-adjuvant activities and/or their binding affinities to the adjuvant-like substances: proteolytic enzymes, lipid binding proteins, chitin binding proteins, and allergens not associated with adjuvant-like activity. In general, allergens with a strong adjuvant-like activity or adjuvant-binding activity elicit potent IgE reactivity. In Korea, Der f 2 is the most potent allergen, followed by Der f 1. Immune responses are modulated by the properties of the allergen itself and by the adjuvant-like substances that are concomitantly administered with the antigens. Characterization of allergenic molecules and elucidation of mechanisms by which adjuvant-like molecules modulate allergic reactions, not only in Korea but also worldwide, will provide valuable information on allergic diseases, and are necessary for the development of diagnostic tools and therapeutic strategies.

Reduced Allergenic Potency of VR9-1, a Mutant of the Major Shrimp Allergen Pen a 1 (Tropomyosin)

The major shrimp allergen, tropomyosin, is an excellent model allergen for studying the influence of mutations within the primary structure on the allergenic potency of an allergen; Pen a 1 allows systematic evaluation and comparison of Ab-binding epitopes, because amino acid sequences of both allergenic and nonallergenic tropomyosins are known. Individually recognized IgE Ab-binding epitopes, amino acid positions, and substitutions critical for IgE Ab binding were identified by combinatorial substitution analysis, and 12 positions deemed critical were mutated in the eight major epitopes. The mutant VR9-1 was characterized with regard to allergenic potency by mediator release assays using sera from shrimp-allergic subjects and sera from BALB/c, C57BL/6J, C3H/HeJ, and CBA/J mice sensitized with shrimp extract using alum, cholera toxin, and Bordetella pertussis, as adjuvants. The secondary structure of VR9-1 was not altered; however, the allergenic potency was reduced by 90-98% measuring allergen-specific mediator release from humanized rat basophilic leukemia (RBL) cells, RBL 30/25. Reduced mediator release of RBL-2H3 cells sensitized with sera from mice that were immunized with shrimp extract indicated that mice produced IgE Abs to Pen a 1 and to the same epitopes as humans did. In conclusion, data obtained by mapping sequential epitopes were used to generate a Pen a 1 mutant with significantly reduced allergenic potency. Epitopes that are relevant for human IgE Ab binding are also major binding sites for murine IgE Abs. These results indicate that the murine model might be used to optimize the Pen a 1 mutant for future therapeutic use.

Sequence Tag Catalogs of Dust Mite-Expressed Genomes

Dust mites are a major source of indoor allergens. They contain a large number of components that react with immunoglobulin (Ig) E in individuals with allergies and are capable of inducing sensitization, and allergic respiratory and cutaneous diseases. With a significant proportion of the population affected in some way by mite allergies, it is essential that we improve our understanding of these organisms so that control strategies could be defined and its allergens better understood. Thus, we have initiated a project using the expressed sequence tagging (EST) strategy to study the major species of dust mites associated with allergic diseases, in particular, the American house dust mite, Dermatophagoides farinae, as well as Blomia tropicalis, the most prevalent mite in domestic tropical dwellings. The work has recently been expanded to include 'storage' mites such as Tyrophagus putrescentiae, Acarus siro, Lepidoglyphus destructor, Glycyphagus domesticus, Suidasia medanensis, and Aleuroglyphus ovatus. More than 50% of the initial 3000 ESTs from the D. farinae and B. tropicalis dust mites showed significant matches to known genes and were categorized into eight functional groups (such as proteins involved in metabolism, gene expression, protein synthesis, cell signaling, etc.). Of specific interest, however, were the homologs to known mite allergens, in addition to a number of sequences bearing significant homology to allergens from non-mite sources previously not known to exist in mites. The availability of these allergen sequences has facilitated their expression and subsequent characterization in our laboratory in terms of their IgE-binding reactivity. The wealth of sequence information, generated via the EST project, has also facilitated the identification of polymorphic forms of allergens, the investigation of differential gene expression under various environmental conditions via DNA microarrays, as well as the analysis of protein level expression profiling via the proteomics approach. Additionally, ESTs have also ameliorated the understanding of the phylogenetic relationships between mites, and enabled the isolation of gene products crucial for life processes so that mite control strategies can be more effectively devised. Taken together, the utilization of the EST strategy has opened up numerous new avenues by which the allergist can engage more effectively in the study of dust mites with the ultimate aim of developing appropriate treatment regimens for mite-induced allergy.

Comparative allergenicity studies of native and recombinant Blomia tropicalis Paramyosin (Blo t 11)

BACKGROUND

The complementary DNA (cDNA) encoding for Blo t 11, a 102 kD allergen from Blomia tropicalis (Bt) was isolated, expressed and characterized previously. This study aimed to isolate the native Blo t 11 allergen and compare its allergenicity with the recombinant forms.

METHODS

Native Blo t 11 (nBlo t 11) was isolated from crude Bt extract by immuno-affinity chromatography, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot, and verified by MALDI-TOF MS. Recombinant full-length Blo t 11 (rFL-Blo t 11) and its immunodominant peptide (fD) were expressed as glutathione S-transferase (GST)-fusion proteins in Escherichia coli. Immunoglobulin E (IgE) reactivity of the Blo t 11 allergens were determined by enzyme-linked immunosorbent assay (ELISA) and skin prick test. The inhibition capacity of the nBlo t 11 against fD and vice versa was determined by absorption studies.

RESULTS

Affinity purified nBlo t 11 was susceptible to degradation with the major degraded product resolved at approximately 66 kD. The nBlo t 11 was confirmed by immunoblot analysis and MALDI-TOF MS that generated 13 peptides with complete identity to the deduced amino acid sequence of Blo t 11. Comparative in vitro and in vivo allergenicity tests and the cross inhibition studies between the native and recombinant Blo t 11 showed that recombinant fD, but not the rFL-Blo t 11, has comparable IgE reactivity with the native counterpart.

CONCLUSIONS

This comparative study confirmed that the recombinant peptide fD contains the main immunodominant region of Blo t 11. This recombinant peptide, instead of the full-length protein, is a good candidate for diagnostic and therapeutics development for mite allergy.

Molecular and immunological characterization of the C-terminal region of a new Echinococcus granulosus Heat Shock Protein 70

By screening an expression library of Echinococcus granulosus with IgE from sera of patients with cystic echinococcosis (CE) and allergic reactions, we isolated the C-terminal region of a new heat shock protein (HSP)70 of E. granulosus. The protein, named Eg2HSP70, has close homology with the C-terminal region of Dermatophagoides farinae and human HSP70. We investigated the humoral and cell-mediated immune responses to this antigen in patients with CE grouped according to the presence of allergic reactions. Immunoblotting detected total IgG, IgG4 and IgE specific to Eg2HSP70 (83% of sera contained IgG, 31% IgG4 and 57% IgE). No significant difference was found in immunoglobulin percentages according to the presence of allergic reactions. Immunoblotting inhibition showed that no IgG or IgE specific to Eg2HSP70 cross-reacted with D. farinae or human HSP70. Eg2HSP70-stimulated PBMC from 26 patients produced significantly greater amounts of TNF-alpha, IFN-gamma, and IL-10 than unstimulated cultures in all patients, irrespective of the presence of allergic reactions (P < 0.05). They also produced significantly greater amounts of IL-4 than unstimulated cultures exclusively in patients with allergic reactions (P < 0.05). These findings show that Eg2HSP70 is a new antigenic molecule inducing both B and T cell responses.

Der f 16: a novel gelsolin-related molecule identified as an allergen from the house dust mite, Dermatophagoides farinae

Allergen from the house dust mite (Dermatophagoides sp.) is a major trigger factor of allergic disorders, and its characterization is crucial for the development of specific diagnosis or immunotherapy. Here we report the identification of a novel dust mite (Dermatophagoides farinae) antigen whose primary structure belongs to the gelsolin family, a group of actin cytoskeleton-regulatory proteins. Isolated mite cDNA, termed Der f 16, encodes 480 amino acids comprising a four-repeated gelsolin-like segmental structure, which is not seen in conventional gelsolin family members. Enzyme immunoassay indicated that recombinant Der f 16 protein, prepared using an Escherichia coli expression system, bound IgE from mite-allergic patients at 47% (8/17) frequency. This is the first evidence that the gelsolin family represents a new class of allergen recognizable by atopic patient IgE.

Heat shock protein (hsp 70)-related epitopes are common allergenic determinants for barley and corn antigens

IgE reactive components of barley and corn were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotted with sera from workers exposed to complex bioaerosols. The antibody made against Arabdopsis heat shock protein (hsp 70) was used to identify those components equivalent to hsp 70 in molecular size. Components with a molecular mass of 69 kDa and 33 kDa were positively reacted, and immunoblots of two-dimensional polyacrylamide gel electrophoresis were compared.

Isolation and characterization of a novel 98-kd Dermatophagoides farinae mite allergen

BACKGROUND

Exposure to allergens from house dust mites is a significant cause of immediate hypersensitivity. Thus far, the active mite allergens defined are low molecular weight (MW) proteins or glycoproteins. However, other important mite allergens remain to be investigated. In this study a high MW mite antigen with a high IgE-binding activity was characterized.

METHODS

An anti-Dermatophagoides farinae (Df) monoclonal antibody, mAb642, which recognized a 98-kd allergenic mite protein, was used for affinity chromatography. The purified Df642 was characterized biochemically and immunologically.

RESULTS

Competitive ELISA demonstrated that mAb642 was inhibited by the interaction between serum IgE from allergic patients and Df642 antigen in a dose-dependent fashion. The IgE reactivity to both 98-kd and 92-kd components was removed or diminished by preincubation of asthmatic sera with Df642-coated CNBr-activated cellulose-4B gel. Two-dimensional immunoblot analysis revealed that there are at least 4 isoforms of Df642 that represent a minor component in the crude mite extract. The allergenicity of Df642 was assayed by IgE immunoassay with a large panel of 67 sera from asthmatic patients with positive skin reactions, and Df 642 showed positive IgE reactivity with more than 80% of the sera tested. Thus it should be classified as an important allergen. In addition, amino acid sequence analysis revealed that Df642 shares more than 50% homology with paramyosin from invertebrates.

CONCLUSION

We have identified and characterized a 98-kd house dust mite allergen that showed greater than 80% IgE reactivity with sera from patients allergic to mites. This is the first high MW allergen characterized to date, and it shares high sequence homology with paramyosins in invertebrates.

Evidence for HSP70-like protein in the RBC membrane of the hereditarily anemic Belgrade laboratory (b/b) rat

We have demonstrated that in normal and b/b rat red blood cells (RBCs) hsp70-like protein (heat shock protein 70-like) is localized in the cytosol and it is exported via exosomes during in vivo reticulocytes maturation. As we have presumed, in the mutant (b/b) rat, hsp70-like protein transfers from cytosol to the RBC membrane. In the normal rat RBCs this happens when those cells are submitted to heat stress conditions. Our study indicates that the presence of hsp70-like protein in the b/b rat RBC plasma membrane is consistent with a primary defect and is not a consequence of life long stress, i.e. hypoxia.

Identification of T-cell epitope sequences on an important mite antigen

BACKGROUND

T-cell epitopes on Der 1 and Der 2 groups, the major mite allergens, have been intensively analysed, while those on the other important allergens remain to be elucidated. We have cloned four cDNAs coding for important mite allergens on the basis of frequency and capacity of IgE binding. Stimulatory action of glutathione S-transferase-fused Mag1 on lymphocytes from mite-allergic patients was relatively high among them.

OBJECTIVE

To identify T-cell epitopes on Mag1, we studied the stimulating activity of truncated Mag1 proteins and synthetic peptides on proliferative response of lymphocytes from mite antigen-immunized mice and mite-sensitive patients.

METHODS

Truncated Mag1 proteins were expressed as a fusion protein with beta-galactosidase in Escherichia coli pop2136 carrying a variety of deleted Mag1 inserts. Murine T-cell epitope regions were estimated by the truncated antigen-induced lymphocyte proliferation assay. Overlapping peptides covering the whole sequence of the presumed T-cell epitope regions were synthesized to identify the epitope core sequences using murine and human Mag1-specific T-cell lines.

RESULTS

Amino acid range 56-70 on Mag1 molecule showed remarkable stimulatory action on murine T cells, while amino acid ranges 51-65 and 86-100 had potent stimulatory activity on human T cells.

CONCLUSIONS

These results suggest that Mag1 is a valuable antigen suitable for studies on T-cell responses and T-cell epitopes in mice and humans.

Cloning and characterization of a new allergen, Mag 3, from the house dust mite, Dermatophagoides farinae: cross-reactivity with high-molecular-weight allergen

A new immunoreactive clone whose sequence is not homologous to that of any of the previously identified mite allergens was isolated by successive immunoscreening of a Dermatophagoides farinae cDNA library with rabbit antisera to an extract of the house dust mite and IgE in pooled sera from patients allergic to mites. Rabbit antibodies specific for the recombinant protein recognized a 177 kD protein in a mite body extract. This immunoreactive protein was located in the circumferential tissues of esophagus, gut and the other internal organs in mites. The reaction of human IgE to the purified natural antigen was inhibited competitively to 30% by the recombinant antigen. In terms of the frequency and the intensity of response to specific IgE in sera from asthmatic patients, the natural protein was similar to Der f2, while the recombinant protein was slightly less allergenic by these criteria. We conclude that the natural protein from the house dust mite, D. farinae, is an important allergen.

B cell mitogenic activity of house dust mite, Dermatophagoides farinae, antigens

The effect of mite antigens on murine and human lymphocytes was studied in vitro. Antigens prepared from Dermatophagoides farinae feces and bodies stimulated normal murine spleen cells to proliferate in a dose-dependent manner. The responder cells are B cells, because the response was reduced by the treatment of spleen cells with anti-immunoglobulin antibody and complement, but not with anti-Thy 1 antibody and complement. Furthermore, nylon column-purified T cells did not respond. The stimulation of B cells with mite antigens was not due to the contamination of lipopolysaccharide, a representative B cell mitogen, because C3H/HeJ spleen cells which are low responders to lipopolysaccharide could respond to mite antigens. These antigens induced not only proliferative response of murine B cells, but also immunoglobulin production. By gel-filtration column chromatography, the active fractions were eluted around the molecular weight of 150-155 kDa. Furthermore, mite antigens also stimulated human B cells to proliferate and to produce immunoglobulin. All these results suggest that mite antigens are a potent B cell mitogen and this activity might concern the induction of allergic reaction.

Stress proteins in inflammation

Inflammation provides those searching in the field with a number of "models" allowing them to study, in vivo, in humans and in animals, the regulation and the functions of HSP, which are being considered as a new and promising marker for the severity and the prognosis of inflammatory diseases. HSP are differentially regulated according to the type of inflammation, whether acute or chronic, whether self-limiting (inflammatory cell elimination by apoptosis) or self-perpetuating (inflammatory cell death by necrosis). We propose that mitochondria are a key organelle in determining the outcome of inflammation, because they are both the cellular "switchboard" for apoptosis and a selective target for the protective effects of HSP against the cytotoxic effects of TNF alpha and ROS. On the other hand, HSP exert multiple protective effects in inflammation, including self/non-self discrimination, enhancement of immune responses, immune protection, thermotolerance and protection against the cytotoxicity of inflammatory mediators. The latter protective effects against the deleterious effects of the mediators of inflammation, including ROS and cytokines, open new avenues for the development of original anti-inflammatory therapies, such as non-toxic inducers of a complete HS response. It may well be that the "beneficial effects of fever" already described by Hippocrates actually relate to increased HSP expression during fever, and to their protective effects....

Immunochemical characterization of recombinant and native tropomyosins as a new allergen from the house dust mite, Dermatophagoides farinae

BACKGROUND

Two predominant mite species, Dermatophagoides farinae and Dermatophagoides pteronyssinus, are responsible for the immediate hypersensitivity reaction. Although a large number of antigens and allergens was detected in a whole mite culture extract, only the major allergens of Der I and II groups have been extensively studied. Much information on other important allergens remains to be accumulated.

METHODS

A new allergen complementary DNA (cDNA) clone was isolated from a D. farinae protein cDNA library. The expression product of the cDNA and native tropomyosin from D. farinae were purified, characterized, and evaluated.

RESULTS

An amino acid sequence deduced from the cDNA clone revealed significant homology with tropomyosins conserved in a wide range of animals. The amino acid sequences of two fragments obtained by degradation of the purified protein with cyanogen bromide coincided completely with the corresponding portions of the deduced amino acid sequence. The native tropomyosin reacted with specific IgE in the 31 sera tested at a high frequency (80.6%), comparable to that of Der f I (90.3%) and Der f II (74.2%).

CONCLUSIONS

The cloned cDNA encodes tropomyosin. The high binding response of specific IgE antibodies to recombinant and native tropomyosins demonstrates that mite tropomyosin is an additional important allergen in house dust mite.