IgA response in serum and gut secretion in sensitized mice fed with the dust mite Dermatophagoides pteronyssinus extract

Induced oral tolerance to mucosal-exposed antigens in immunized animals is of particular interest for the development of immunotherapeutic approaches to human allergic diseases. This is a unique feature of mucosal surfaces which represent the main contact interface with the external environment. However, the influence of oral tolerance on specific and natural polyreactive IgA antibodies, the major defense mechanism of the mucosa, is unknown. We have shown that oral administration of an extract of the dust mite Dermatophagoides pteronyssinus (Dp) to primed mice caused down-regulation of IgE responses and an increase in tumor growth factor-ß secretion. In the present study, we observed that primed inbred female A/Sn mice (8 to 10 weeks old) fed by gavage a total weight of 1.0-mg Dp extract on the 6th, 7th and 8th days post-immunization presented normal secretion of IL-4 and IL-10 in gut-associated lymphoid tissue and a decreased production of interferon gamma induced by Dp in the draining lymph nodes (13,340 ± 3,519 vs 29,280 ± 2,971 pg/ml). Mice fed the Dp extract also showed higher levels of serum anti-Dp IgA antibodies and an increase of IgA-secreting cells in mesenteric lymph nodes (N = 10), reflecting an increase in total fecal IgA antibodies (N = 10). The levels of secretory anti-Dp IgA antibodies increased after re-immunization regardless of Dp extract feeding. Oral tolerance did not interfere with serum or secretory IgA antibody reactivity related to self and non-self antigens. These results suggest that induction of oral tolerance to a Dp extract in sensitized mice triggered different regulatory mechanisms which inhibited the IgE response and stimulated systemic and secretory IgA responses, preserving the natural polyreactive IgA antibody production.

Respiratory allergy to Blomia tropicalis: Immune response in four syngeneic mouse strains and assessment of a low allergen-dose, short-term experimental model

Background: The dust mite Blomia tropicalis is an important source of aeroallergens in tropical areas. Although a mouse model for B. tropicalis extract (BtE)-induced asthma has been described, no study comparing different mouse strains in this asthma model has been reported. The relevance and reproducibility of experimental animal models of allergy depends on the genetic background of the animal, the molecular composition of the allergen and the experimental protocol. Objectives: This work had two objectives. The first was to study the anti-B. tropicalis allergic responses in different mouse strains using a short-term model of respiratory allergy to BtE. This study included the comparison of the allergic responses elicited by BtE with those elicited by ovalbumin in mice of the strain that responded better to BtE sensitization. The second objective was to investigate whether the best responder mouse strain could be used in an experimental model of allergy employing relatively low BtE doses. Methods: Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 mu g of BtE on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 mu g of BtE. A/J mice, that were the best responders to BtE sensitization, were used to compare the B. tropicalis-specific asthma experimental model with the conventional experimental model of ovalbumin (OVA)-specific asthma. A/J mice were also sensitized with a lower dose of BtE. Results: Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-BtE IgE antibodies, but these responses were significantly more intense in A/J mice than in CBA/J, BALB/c or C57BL/6J mice. Immunization of A/J mice with BtE induced a more intense airway eosinophil influx, higher levels of total IgE, similar airway hyperreactivity to methacholine but less intense mucous production, and lower levels of specific IgE, IgG1 and IgG2 antibodies than sensitization with OVA. Finally, immunization with a relatively low BtE dose (10 mu g per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose BtE immunization, for the development of allergy-associated immune and lung inflammatory responses. Conclusions: The described short-term model of BtE-induced allergic lung disease is reproducible in different syngeneic mouse strains, and mice of the A/J strain was the most responsive to it. In addition, it was shown that OVA and BtE induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of BtE.

Computational tools for the study of allergens

Allergy is a major cause of morbidity worldwide. The number of characterized allergens and related information is increasing rapidly creating demands for advanced information storage, retrieval and analysis. Bioinformatics provides useful tools for analysing allergens and these are complementary to traditional laboratory techniques for the study of allergens. Specific applications include structural analysis of allergens, identification of B- and T-cell epitopes, assessment of allergenicity and cross-reactivity, and genome analysis. In this paper, the most important bioinformatic tools and methods with relevance to the study of allergy have been reviewed.

Development of an animal model for allergic conjunctivitis: influence of genetic factors and allergen concentration on immune response

Purpose: Animal models of diseases are extremely important in the study of the physiopathogenesis of human diseases and for testing novel therapeutic interventions. The present study aimed to develop an animal model that simulates human allergic conjunctivitis and to study how allergic response may be influenced by the allergen dose used for immunization and by genetic factors. Methods: Sixty C57Bl/6 mice and 60 BALB/c mice were immunized with placebo, or 5 mu g or 500 mu g of allergen derived from Dermatophagoides pteronyssinus. After ocular challenge, the mice were examined in order to clinically verify the occurrence or not of conjunctivitis. Material obtained from animals was used for total and specific IgE and IgG1 dosage, for assays of Der p-specific lymphocyte proliferation and supernatant cytokine dosage, and for histopathological evaluation of conjunctiva. Results: We developed a murine model of allergic conjunctivitis induced by D. pteronyssinus. The model is similar to human disease both clinically and according to laboratory findings. In mouse, conjunctivitis was associated with a Th2 cytokine profile. However, IL-10 appeared to be involved with disease blockade. Mice of different strains have distinct immune responses, depending on the sensitization dose. Conclusions: The murine model developed is suitable for the study of immunopathogenesis and as a template for future therapies. Using BALB/c and C57BL/6 mice, we demonstrated that genetic factors play a role in determining susceptibility and resistance, as well as in establishing the allergen concentration needed to induce or to block disease development.

Balance between early life tolerance and sensitization in allergy: dependence on the timing and intensity of prenatal and postnatal allergen exposure of the mother

P>Allergens can be maternally transferred to the fetus or neonate, though it is uncertain how this initial allergen exposure may impact the development of allergy responses. To evaluate the roles of timing and level of maternal allergen exposure in the early life sensitization of progeny, female BALB/c mice were given ovalbumin (OVA) orally during pregnancy, lactation or weekly at each stage to investigate the immunoglobulin E (IgE) antibody production and cellular responsiveness of their offspring. Exposure to OVA during pregnancy was also evaluated in OVA-specific T-cell receptor (TCR) transgenic (DO11.10) mice. The effect of prenatal antigen exposure on offspring sensitization was dependent on antigen intake, with low-dose OVA inducing tolerance followed by neonatal immunization that was sustained even when pups were immunized when 3 weeks old. These offspring received high levels of transforming growth factor-beta via breastfeeding. High-dose exposure during the first week of pregnancy or perinatal period induced transient inhibition of IgE production following neonatal immunization; although for later immunization IgE production was enhanced in these offspring. Postnatal maternal antigen exposure provided OVA transference via breastfeeding, which consequently induced increased offspring susceptibility to IgE antibody production according to week post-birth. The effect of low-dose maternal exposure during pregnancy was further evaluated using OVA transgenic TCR dams as a model. These progeny presented pronounced entry of CD4(+) T cells into the S phase of the cell cycle with a skewed T helper type 2 response early in life, revealing the occurrence of allergen priming in utero. The balance between tolerance and sensitization depended on the amount and timing of maternal allergen intake during pregnancy.

Measurement of IgE antibodies to shrimp tropomyosin is superior to skin prick testing with commercial extract and measurement of IgE to shrimp for predicting clinically relevant allergic reactions after shrimp ingestion

Background: Shrimp is a frequent cause of food allergy. Tropomyosin is the major allergen in shrimp, and it shares homology to tropomyosins from other crustaceans, dust mites, cockroach, and parasites. Objective: The aim of this study was to determine the value of detection of IgE to shrimp tropomyosin in the diagnosis of shrimp allergy. Methods: We have studied 35 patients with asthma, rhinitis, or both who were sensitized to Dermatophagoides pteronyssinus. All subjects underwent skin prick testing in addition to double-blind, placebo-controlled food challenges (DBPCFC); oral open challenges; or both with shrimp. Measurements of IgE to shrimp and shrimp tropomyosin were carried out by means of CAP and chimeric ELISA, respectively. Results: Oral challenges confirmed the diagnosis of shrimp allergy in 7 patients. IgE measurement to shrimp tropomyosin was positive in 71.4% of the patients with shrimp allergy. Of the 28 patients without shrimp allergy, only 7.1% (2/28) had IgE to shrimp tropomyosin compared with 25% (7/28) who had IgE to shrimp and 35.7% (10/28) who had positive skin prick test responses to shrimp. Sensitivity was similar for all 3 methods (71.4%); in contrast, specificity of IgE to shrimp tropomyosin (92.8%) was greater than that of IgE to shrimp (75%) and skin prick testing (64.2%). With regard to diagnostic efficiency, measurement of IgE to shrimp tropomyosin was superior to measurement of IgE to shrimp and skin prick testing (88.5%, 74.2%, and 65.7%, respectively). Conclusion: Use of measurements of IgE to shrimp tropomyosin provided added value to the diagnosis of shrimp allergy. (J Allergy Clin Immunol 2010;125:872-8.)

Impact of specific sensitization on asthma and rhinitis in young Brazilian and Chilean adults

Background The pattern of associations and the attributable fractions (AF) of atopic conditions due to specific sensitizations vary between countries. Objective To assess the level of associations and AF between sensitization to five allergens and atopic conditions in two settings. Methods We studied 2063 Brazilians and 1231 Chileans of both sexes using representative samples selected at birth in the 1970s. Information on asthma and rhinitis was based on the European Community Respiratory Health Survey questionnaire. We assessed bronchial hyperresponsiveness (BHR) to methacholine and sensitization to Dermatophagoides pteronyssinus, cat, dog, grass blend and Alternaria alternata. Results The prevalence of sensitization to one or more allergens was 50% in Brazilians and 22% in Chileans. The level of associations varied according to the outcome used. Strong associations between sensitization and asthma, defined as wheeze or awakening with breathlessness at night and positive BHR, were found for each of the five allergens in Chileans [varying from odds ratio (OR) 3.24, 95% confidence interval (CI) 1.47, 7.15 for D. pteronyssinus to 8.44, 95% CI 3.82, 18.66 for cat], whereas the level of associations was restricted to D. pteronyssinus, cat and dog in Brazilians and was somewhat weaker (highest OR 3.90, 95% CI 2.80-5.44). The AF of sensitization on asthma was 54% in Brazil and 44% in Chile. D. pteronyssinus and cat made an independent contribution to asthma in the two samples. The patterns of associations between sensitization and rhino-conjunctivitis were similar to those for asthma. Conclusion The associations between sensitization, and asthma and rhinitis were high in Chile and moderately high in Brazil, but the AF were higher in Brazil, reflecting a higher prevalence of sensitization. In Brazil, dust mite had the greatest impact on atopic conditions while in Chile several allergens had an impact. Sensitization is as serious a problem in Chile and Brazil as in developed countries.

Diversidade da exposição alergênica: implicações na obtenção da eficácia do controle ambiental

As doenças alérgicas, como a asma, rinite, conjuntivite alérgica e a dermatite atópica têm apresentado um aumento na sua prevalência nas últimas décadas. A relação entre exposição alergênica, sensibilização atópica e desenvolvimento de doenças alérgicas são amplamente descrita na literatura. OBJETIVO: Discutir a dificuldade no controle ambiental da exposição alergênica como parte do tratamento das doenças alérgicas. MÉTODOS: Analisar trabalhos de exposição alergênica realizados com metodologia similar na região central do Brasil, incluindo casas, hotéis, cinemas, carros, táxis, ônibus e transporte escolar. RESULTADOS: Níveis elevados dos alérgenos do grupo 1 de Dermatophagoides pteronyssinus (Der p 1) e de D. farinae (Der f 1), capazes de causar sensibilização e exacerbação de sintomas foram encontrados na maioria dos ambientes estudados em uma larga proporção das amostras, enquanto os alérgenos de animais domésticos atingiram maiores níveis em carros e veículos de transporte escolar. CONCLUSÃO: A diversidade da exposição alergênica mostra a necessidade de uma compreensão da doença alérgica pelos pacientes e familiares, e que as medidas de controle do ambiente doméstico fazem parte de uma estratégia global do tratamento das doenças alérgicas, uma vez que os indivíduos vivem em uma sociedade e não isoladas no interior de seus domicílios.

Barnacle Allergy: Allergen Characterization and Cross-Reactivity with Mites

Background: Barnacles are a type of seafood with worldwide distribution and abundant along the shores of temperate seas. They are particularly appreciated and regularly consumed in Portugal as well as in Spain, France and South America, but barnacle allergy is a rare condition of which there is only one reference in the indexed literature. The molecular allergens and possible cross-reactivity phenomena implicated (namely with mites) have not been established. Objective: To demonstrate the IgE-mediated allergy to barnacle and to identify the proteins implicated as well as possible cross-reactivity phenomena with mites. Methods: We report the clinical and laboratory data of five patients with documented IgE-mediated allergy to barnacle. The diagnosis was based on a suggestive clinical history combined with positive skin prick tests (SPT) to barnacle – prick to prick method. Two barnacle extracts were prepared (raw and cooked barnacle) and sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) and IgE-immunoblotting were performed. An immunoblotting inhibition assay with Dermatophagoides pteronyssinus was also done in order to evaluate cross-reactivity. Results: All patients had mite-related asthma and the allergic rhinoconjunctivitis; they all experienced mucocutaneous symptoms. All of them had positive SPT to barnacle, and the immunoblotting showed several allergenic fractions with a wide molecular weight range (19 – 94 kDa). The D. pteronyssinus extract inhibited several IgE-binding protein fractions in the barnacle extract. Conclusions: We describe five patients with IgE-mediated barnacle allergy. We also describe a group of IgEbinding+ proteins between 30 and 75 kDa as the allergenic fractions of this type of Crustacea. Cross-reactivity with D. pteronyssinus was demonstrated in two cases.

Effectiveness of house dust mite acaricide tri-n-butyl tin maleate on carpets, fabrics and mattress foam: a standardization of methodology

The aim of this study was to determine the effectiveness of the acaricide tri-n-butyl tin maleate, industrially applied to samples of carpets, mattress foam, and fabrics used for furniture upholstery, soft toys and shoe uppers. Approximately 100 adult house dust mites of the species Dermatophagoides pteronyssinus were inoculated into a Petri dish containing the sample (a piece of carpet, mattress foam, or fabric), treated with the acaricide, randomly collected. Mite-maintenance culture medium was added on top of each sample. After one, two, three, seven and 30 days of incubation at 25 ºC and 75% relative humidity, each dish was examined using a 40X stereoscopic microscope (40X). One hundred percent acaricide effectiveness was obtained in treated materials by the end of the 30th-day postinoculation period, under optimal conditions for mite maintenance.

Avaliação da presença de ácaros em cereais armazenados na grande São Paulo

O exame microscópico de 160 amostras de cereais (arroz, feijão, trigo, milho, a veia, ervilha e sorgo), 40% fornecidas pelo Instituto Adolfo Lutz e provenientes de distribuidores como COBAL, CIBRAZEM, PETROPACK, CEAGESP, DECOM e do 2º Exército, e 60% adquiridas em mercadinhos e armazéns na Grande São Paulo, feito no ato e após 42 dias de incubação a 25°C e 70% UR revelou que 49% das amostras apresentavam populações de ácaros primários de alimentos armazenados. Destas, 48% revelaram a presença de Tyrophagus putrescentiae (Schrank), 17,5% Aleuroglyphus ovatus (Troupeau), 6,8% Glycyphagus domesticus (DeGeer), 4,37% Chortoglyphus arcuatus (Troupeau), 3,8% Suidasia pontifica Oudemans, 3,12% Blomia tropicallis Bronswijck, Cook & Oshima, 1,25% Histiostoma sp. e Dermatophagoides pteronyssinus (Trouessart). Ácaros secundários também foram encontra dos destacando-se Tarsonemus sp., Cheyletus malaccensis Oudemans e Blattisocius dentriticus (Berlese), entre outros. As amostras originárias dos grandes distribuidores apresentavam bem menos ácaros do que aquelas dos pequenos armazéns onde a rotatividade de estoque é bem menor. O resultado positivo para ácaros de amostras mantidas em incubador por 42 dias quando seu exame no ato não os revelou, mostra que o simples exame de uma amostra de cereal num dado momento não exclui a hipótese dele estar contaminado por ovos de ácaros primários de alimentos. Dentre os insetos, o mais frequente foi o gorgulho Sitophilus orizae (L.) presente em amostras de arroz, milho e trigo.

Ácaros em poeira domiciliar das capitais brasileiras e ilha Fernando de Noronha

O presente trabalho é um estudo taxinômico de ácaros admitidos ou não como alergizantes, encontrados em amostras de poeira domiciliar, colhidas em todas as capitais do Brasil e Território Fernando de Noronha por guardas da SUCAM e enviadas por essa entidade ao Professor Leonidas de Mello Deane. Foram classificadas dez espécies pertencentes a cinco famílias, cujas posições sistemáticas são determinadas por definições e chaves: Pyroglyphus africanus, Euroglyphus maynei, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Dermatophagoides deanei, Sturnophagoides brasiliensis, Blomia tropicalis, Suidasia pontifica, Chortoglyphus arcuatus e Cheyletus malaccensis.

Evaluation of the acarofauna of the domiciliary ecosystem in Juiz de Fora, State of Minas Gerais, Brazil

From August 1999 to January 2000, samples of house dust were collected from 160 domiciles in the city of Juiz de Fora, State of Minas Gerais, Brazil. In 36 of these domiciles kitchen samples were obtained. Prevalence rate was 77.5%, varying according to the geographical sector. There were found 2,278 specimens of mites, with 1,530 (67.2%) in the adult stage and 748 (32.8%) in immature forms. The main species found were Dermatophagoides pteronyssinus, D. farinae, Euroglyphus maynei, Blomia tropicalis and Tyrophagus putrescentiae. In a minor incidence we found Lepidoglyphus destructor, Suidasia pontificiae, Chortoglyphus arcuatus, Cheyletus malaccensis, C. fortis, Ker bakeri, Cheletonella vespertilionis, C. caucasica and others. C. vespertilionis and C. caucasica were identified for the first time in the domiciliary ecosystem and in Brazil. The abundance rate and the infestation intensity were analyzed. There was a varied correlation between climatic conditions and positive domiciles and number of mites. The difference between the number of positive domiciles in the urban area and in the expanding urban area was significant and so was the difference between samples from the domiciles compared to those from the kitchens.

Evaluation of skin sensitivity in dogs bearing allergic dermatitis to standardized allergenic extract of house dust and storage mites

The objective of the study was to evaluate whether allergenic extracts of five house dust and storage mite species standardized for humans might be used for the diagnosis of canine atopic dermatitis (CAD). Extracts of Dermatophagoides pteronyssinus (Pyroglyphidae), D. farinae (Pyroglyphidae), Blomia tropicalis (Glycyphagidae), Lepidoglyphus destructor (Glycyphagidae) and Tyrophagus putrescentiae (Acaridae) were evaluated by intradermal testing in 20 healthy dogs (control) and 25 dogs with allergic dermatitis. A significant difference in the response was observed between the two groups (p<0.05). Only one dog (5%) in the control group reacted to the intradermal test, whereas 14 dogs (56%) in the allergic group were positive for at least one extract (odds ratio = 24.2). Most of the positive reactions observed in the allergic group occurred against the extracts of T. putrescentiae or L. destructor, each inducing reactions in 10 dogs (40%). D. farinae, D. pteronyssinus e B. tropicalis extracts induced reactions in 7 (28%), 3 (12%) and 3 (12%) dogs, respectively. The allergenic extracts standardized for humans evaluated in the present study may be used as a tool to complement the diagnosis of the disease, as well as to select potential allergen candidates for allergen-specific immunotherapy.

Responses of IgE, IgG1, and IgG4 to concanavalin A-binding Blomia tropicalis antigens in allergic patients

Blomia tropicalis (Bt) and Dermatophagoides pteronyssinus (Dp) are the prevalent house dust mites in tropical countries and are associated with allergic diseases. Glycosylated antigens are highly immunogenic and involved in different pathologies. We evaluated the presence of IgE, IgG1, and IgG4 to concanavalin A-binding antigens (Bt-Con-A) isolated from Bt-total extract in sera of allergic and non-allergic subjects. Bt-total and Bt-Con-A extracts were evaluated by SDS-PAGE and ELISA for reacting with IgE, IgG1, and IgG4 in sera of 121 patients with allergic rhinitis and 36 non-allergic individuals. All subjects were skin prick tested with Bt-total extract and inhibition tests were performed for IgE, IgG1, and IgG4 using both extracts (Bt-total and Bt-Con-A). Skin prick test showed that 58% of the patients were sensitized to Bt (Bt+), with 52% reactive to both mites (Bt and Dp) and 6% to Bt only. A broad spectrum of proteins (14-152 kDa) was visualized in Bt-total and components >27 kDa for the Bt-Con-A extract. ELISA showed a similar profile of IgE, IgG1 and IgG4 levels in response to Bt-total and Bt-Con-A extracts in different groups, although Bt+ patients showed a lower IgG4 reactivity to Bt-Con-A extract. Specific IgG1 levels were higher in Bt+ patients than in control subjects, and IgG4 levels showed no significant difference among groups. ELISA inhibition showed a partial IgE and total IgG1 and IgG4 cross-reactivity with Dp extract for Bt-total and Bt-Con-A extracts. We conclude that Con-A-binding components isolated from Bt constitute major allergens and are involved in both allergen sensitization (IgE response) and homeostasis maintenance (IgG1 and IgG4 responses).