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

<p>Abstract</p> <p>Background</p> <p>The dust mite <it>Blomia tropicalis </it>is an important source of aeroallergens in tropical areas. Although a mouse model for <it>B. tropicalis </it>extract (<it>Bt</it>E)-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.</p> <p>Objectives</p> <p>This work had two objectives. The first was to study the anti-<it>B. tropicalis </it>allergic responses in different mouse strains using a short-term model of respiratory allergy to <it>Bt</it>E. This study included the comparison of the allergic responses elicited by <it>Bt</it>E with those elicited by ovalbumin in mice of the strain that responded better to <it>Bt</it>E 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 <it>Bt</it>E doses.</p> <p>Methods</p> <p>Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 μg of <it>Bt</it>E on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 μg of <it>Bt</it>E. A/J mice, that were the best responders to <it>Bt</it>E sensitization, were used to compare the <it>B. tropicalis</it>-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 <it>Bt</it>E.</p> <p>Results</p> <p>Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-<it>Bt</it>E 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 <it>Bt</it>E 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 <it>Bt</it>E dose (10 μg per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose <it>Bt</it>E immunization, for the development of allergy-associated immune and lung inflammatory responses.</p> <p>Conclusions</p> <p>The described short-term model of <it>Bt</it>E-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 <it>Bt</it>E induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of <it>Bt</it>E.</p

Rapid Effects of Marine Reserves via Larval Dispersal

Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest

Dissociation between skin test reactivity and anti-aeroallergen IgE: Determinants among urban Brazilian children.

BACKGROUND: The dissociation between specific IgE and skin prick test reactivity to aeroallergens, a common finding in populations living in low and middle-income countries, has important implications for the diagnosis and treatment of allergic diseases. Few studies have investigated the determinants of this dissociation. In the present study, we explored potential factors explaining this dissociation in children living in an urban area of Northeast Brazil, focusing in particular on factors associated with poor hygiene. METHODS: Of 1445 children from low income communities, investigated for risk factors of allergies, we studied 481 with specific IgE antibodies to any of Blomia tropicalis, Dermatophagoides pteronyssinus, Periplaneta americana and Blatella germanica allergens. Data on demographic, environmental and social exposures were collected by questionnaire; serum IgG and stool examinations were done to detect current or past infections with viral, bacterial, protozoan and intestinal helminth pathogens. We measured atopy by skin prick testing (SPT) and specific IgE (sIgE) to aerollergens in serum (by ImmunoCAP). SIgE reactivity to B. tropicalis extract depleted of carbohydrates was measured by an in-house ELISA. Total IgE was measured by in house capture ELISA. SNPs were typed using Illumina Omni 2.5. RESULTS: Negative skin prick tests in the presence of specific IgE antibodies were frequent. Factors independently associated with a reduced frequency of positive skin prick tests were large number of siblings, the presence of IgG to herpes simplex virus, Ascaris lumbricoides and Trichuris trichiura infections, living in neighborhoods with infrequent garbage collection, presence of rodents and cats in the household and sIgE reactivity to glycosylated B. tropicalis allergens. Also, SNP on IGHE (rs61737468) was negatively associated with SPT reactivity. CONCLUSIONS: A variety of factors were found to be associated with decreased frequency of SPT such as unhygienic living conditions, infections, total IgE, IgE response to glycosylated allergens and genetic polymorphisms, indicating that multiple mechanisms may be involved. Our data, showing that exposures to an unhygienic environment and childhood infections modulate immediate allergen skin test reactivity, provide support for the "hygiene hypothesis"

Prevalência de asma em adolescentes na cidade de Fortaleza, CE Prevalence of asthma among adolescents in the city of Fortaleza, Brazil

OBJETIVO: Avaliar a prevalência de asma em adolescentes (13-14 anos) na cidade de Fortaleza, CE. MÉTODOS: Estudo transversal utilizando o questionário do International Study of Asthma and Allergies in Childhood e envolvendo 3.015 adolescentes de escolas públicas e privadas entre 2006 e 2007. RESULTADOS: As prevalências de "sibilos alguma vez na vida", "sibilos nos últimos doze meses" (asma ativa) e "asma alguma vez na vida" (asma diagnosticada) foram, respectivamente, 44,1%, 22,6% e 11,6%. As prevalências de "sibilos alguma vez na vida" (p = 0,001), "1-3 crises de sibilos nos últimos 12 meses" (p = 0,001); asma ativa (p = 0,002); "sono interrompido por sibilos menos que uma vez por semana" (p < 0,001) e "tosse seca noturna" (p < 0,001) foram maiores nas adolescentes. Alunos de escolas privadas apresentaram maior prevalência de "sibilos alguma vez na vida", asma ativa, "1-3 crises de sibilos nos últimos 12 meses", "4-12 crises de sibilos nos últimos 12 meses" e asma diagnosticada (p < 0,001 para todos), além de "sibilos após exercícios" (p = 0,032). CONCLUSÕES: A prevalência de asma e de sintomas associados em escolares de 13-14 anos na cidade de Fortaleza mostrou-se elevada, predominando no sexo feminino e no grupo das escolas privadas. A diferença entre as prevalências de asma diagnosticada e a de asma ativa sugere que a asma foi subdiagnosticada na população estudada.<br>OBJECTIVE: To determine the prevalence of asthma among adolescents (13-14 years of age) in the city of Fortaleza, Brazil. METHODS: This was a cross-sectional study involving 3,015 adolescents at public and private schools between 2006 and 2007. The participants completed the International Study of Asthma and Allergies in Childhood questionnaire. RESULTS: The prevalences of "wheezing ever", "wheezing within the last 12 months" (active asthma) and "asthma ever" (physician-diagnosed asthma) were 44.1%, 22.6% and 11.6%, respectively. The prevalences of "wheezing ever" (p = 0.001), "1-3 wheezing attacks within the last 12 months" (p = 0.001), active asthma (p = 0.002), "sleep disturbed due to wheezing less than one night per week" (p < 0.001) and "dry cough at night" (p < 0.001) were higher among girls. Private school students presented higher prevalences of "wheezing ever", active asthma, "1-3 wheezing attacks within the last 12 months", "4-12 wheezing attacks within the last 12 months" and physician-diagnosed asthma (p < 0.001 for all), as well as of "exercise-induced wheezing" (p = 0.032). CONCLUSIONS: The prevalence of asthma and asthma-related symptoms in students aged 13-14 years in the city of Fortaleza, Brazil, was high, predominantly among girls and private school students. The difference between the prevalence of physician-diagnosed asthma and that of active asthma suggests that asthma was underdiagnosed in the population studied