A study on the immunological basis of the dissociation between type I-hypersensitivity skin reactions to Blomia tropicalis antigens and serum anti-B. tropicalis IgE antibodies

<p>Abstract</p> <p>Background</p> <p>Two conditions are used as markers of atopy: the presence of circulating anti-allergen IgE antibodies and the presence of positive skin prick test (SPT) reactions to allergenic extracts. The correlation between these conditions is not absolute. This study aimed at investigating immunological parameters that may mediate this lack of correlation. Individuals whose sera contained anti-<it>B. tropicalis </it>extract IgE antibodies (α<it>-Bt</it>E IgE) were divided into two groups, according to the presence or absence of skin reactivity to <it>B. tropicalis </it>extract (<it>Bt</it>E). The following parameters were investigated: total IgE levels; α<it>-Bt</it>E IgE levels; an arbitrary α<it>-Bt</it>E IgE/total IgE ratio; the proportion of carbohydrate-reactive α<it>-Bt</it>E IgE; the proportion of α<it>-Bt</it>E IgE that reacted with <it>Ascaris lumbricoides </it>extract (<it>Al</it>E); the production of IL-10 by <it>Bt</it>E- and <it>Al</it>E-stimulated peripheral blood cells (PBMC).</p> <p>Results</p> <p>Total IgE levels were similar in the two groups, but α<it>-Bt</it>E IgE was significantly higher in the SPT-positive group (SPT<b>+</b>). A large overlap of α<it>-Bt</it>E IgE levels was found in individuals of both groups, indicating that these levels alone cannot account for the differences in SPT outcome. Individuals of the two groups did not differ, statistically, in the proportion of α-<it>Bt</it>E IgE that reacted with carbohydrate and in the production of IL-10 by <it>Bt</it>E- and <it>Al</it>E-stimulated PBMC. Both groups had part of α-<it>Bt</it>E IgE activity absorbed out by <it>Al</it>E, indicating the existence of cross-reactive IgE antibodies. However, the α-<it>Bt</it>E IgE from the SPT-negative individuals (SPT-) was more absorbed with <it>AlE </it>than the α-<it>Bt</it>E IgE from the SPT+ individuals. This finding may be ascribed to avidity differences of the α-<it>Bt</it>E IgE that is present in the two groups of individuals, and could occur if at least part of the α-<it>Bt</it>E IgE from the SPT- individuals were elicited by <it>A. lumbricoides </it>infection.</p> <p>Conclusion</p> <p>The present results suggest that a low ratio of specific IgE to total IgE levels (in a minority of individuals), and differences in α-<it>Bt</it>E IgE avidities (which would have high affinities for <it>A. lumbricoides </it>antigens in SPT- than in SPT<b>+ </b>individuals) may play a role in the down-modulation of type-I hypersensitivity reaction against aeroallergens described in helminth-infected individuals.</p

Avaliação da atividade imunomoduladora de extratos de peles e glândulas parotóides de anuros do semi-árido brasileiro

The skin of amphibians has been characterized by the presence of several chemical products with diverse biological activities. These compounds participate as defense mechanisms against pathogens and harmful substances to which amphibians are exposed in their natural habitats. This work aimed to investigate the pharmacological activity of skin and gland extracts prepared from species of anures native or endemic from Brazilian semi-arid region with emphasis on immunomodulatory activity. Aqueous extracts were prepared by homogenization of skins of seven anure species (Hypsiboas crepitans, Hyspsiboas albopunctatus, Bokermannohyla oxente, Leptodactylus ocellatus, Chaunus rubescens, Ceratophrys joazeirensis e Chaunus jimi) and of glands of two species (Chaunus rubescens and Chaunus jimi). To evaluate the inhibition of nitric oxide (NO) production by the extracts, we used J774 cells stimulated with IFN-g and LPS and measured the nitrite concentration using the Griess method 24 hour later. For lymphoproliferation assays, BALB/c mice spleen cells were stimulated in vitro with concanavalin A in the presence or absence of extracts being the proliferative response determined by 3H-thymidine uptake quantification. Of the nine extracts analyzed, five had inhibitory activity superior to 50% in lymphoproliferation assay (skin extract of C. rubescens, B. oxente, Chaunus. jimi, L. ocellatus and gland extract of C. rubescens) and only one extract inhibited NO production (Chaunus rubescens). The results demonstrate that anure species from the Brazilian semi-arid are a potential source of molecules with immunomodulatory activity. Studies aiming to isolate and characterize the active molecule in the skin of C. rubescens are being carried out.A pele dos anfíbios possui uma variedade de produtos químicos com diversas atividades biológicas. Esses compostos participam dos mecanismos de defesa contra patógenos e substâncias estranhas aos quais os anfíbios são expostos em seu habitat. Esse trabalho teve o objetivo de investigar a atividade farmacológica de extratos de peles e glândulas de anuros do semi-árido brasileiro visando à identificação de substâncias com atividade imunomoduladora. Extratos aquosos foram preparados a partir de homogeneização das peles de sete espécies de anuros Hypsiboas crepitans, Hypsiboas albopunctatus, Bokermannohyla oxente, Leptodactylus ocellatus, Chaunus rubescens, Ceratophrys joazeirensis e Chaunus jimi) e das glândulas de duas espécies de anuros (Chaunus rubescens e Chaunus jimi). Para avaliar a inibição da produção de óxido nítrico (NO) pelos extratos, foram utilizadas células da linhagem J774 estimuladas com IFN-g e LPS, medindo-se a concentração de nitrito após 24 horas pelo método de Griess. Nos ensaios de linfoproliferação, esplenócitos de camundongos BALB/c foram estimulados com concanavalina A na presença ou ausência dos extratos, determinando-se a proliferação por meio da avaliação da incorporação de 3H-timidina. Dos nove extratos analisados, cinco apresentaram atividade inibitória superior a 50% no ensaio de linfoproliferação (extrato de pele de C. rubescens, B. oxente, C. jimi, L. ocellatus e de glândula de C. rubescens) e apenas um extrato inibiu a produção de NO (C. rubescens). Os resultados demonstram que os anuros do semi-árido são fontes potenciais de moléculas imunossupressoras. Outros estudos estão sendo realizados com o objetivo de isolar e caracterizar as moléculas ativas na pele de C. rubescens

Spontaneous cytokine production in children according to biological characteristics and environmental exposures.

BACKGROUND: Environmental factors are likely to have profound effects on the development of host immune responses, with serious implications for infectious diseases and inflammatory disorders such as asthma. OBJECTIVE: This study was designed to investigate the effects of environmental exposures on the cytokine profile of children. METHODS: The study involved measurement of T helper (Th) 1 (interferon-gamma), 2 [interleukin (IL)-5 and IL-13], and the regulatory cytokine IL-10 in unstimulated peripheral blood leukocytes from 1,376 children 4-11 years of age living in a poor urban area of the tropics. We also assessed the impact of environmental exposures in addition to biological characteristics recorded at the time of blood collection and earlier in childhood (0-3 years before blood collection). RESULTS: The proportion of children producing IL-10 was greater among those without access to drinking water [p < 0.05, chi-square test, odds ratio (OR) = 1.67]. The proportion of children producing IL-5 and IL-10 (OR = 10.76) was significantly greater in households that had never had a sewage system (p < 0.05, trend test). CONCLUSIONS: These data provide evidence for the profound effects of environmental exposures in early life as well as immune homeostasis in later childhood. Decreased hygiene (lack of access to clean drinking water and sanitation) in the first 3 years of life is associated with higher spontaneous IL-10 production up to 8 years later in life

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

Protective effects of mito-TEMPO against doxorubicin cardiotoxicity in mice

Doxorubicin (DOX) is a chemotherapeutic that is widely used for the treatment of many human tumors. However, the development of cardiotoxicity has limited its use. The aim of the present study was to evaluate the possible efficacy of mito-TEMPO (mito-T) as a protective agent against DOX-induced cardiotoxicity in mice. C57BL/6 mice were treated twice with mito-T at low (5 mg/kg body weight) or high (20 mg/kg body weight) dose and once with DOX (24 mg/kg body weight) or saline (0.1 mL/20 g body weight) by means of intraperitoneal injections. The levels of malondialdehyde (MLDA), a marker of lipid peroxidation, and serum levels of creatine kinase were evaluated 48 h after the injection of DOX. DOX induced lipid peroxidation in heart mitochondria (p < 0.001), and DOX-treated mice receiving mito-T at low dose had levels of MLDA significantly lower than the mice that received only DOX (p < 0.01). Furthermore, administration of mito-T alone did not cause any significant changes from control values. Additionally, DOX-treated mice treated with mito-T at high dose showed decrease in serum levels of total CK compared to mice treated with DOX alone (p < 0.05). Our results indicate that mito-T protects mice against DOX-induced cardiotoxicity.Fundacao de Amparo a Pesquisa do Estado da Bahia-FAPESB, State Government of Bahia, BrazilFundacao Oswaldo Cruz, BrazilConselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq, Ministry of Science and Technology, BrazilFundacao Oswaldo Cruz, Goncallo Moniz Res Ctr, Rua Waldemar Falcao 121, BR-40296710 Salvador, BA, BrazilUniv Fed Sao Paulo, Lab Imunol Celular & Bioquim Fungos & Protozoario, Sao Paulo, BrazilUCL, London, EnglandUniv Fed Sao Paulo, Lab Imunol Celular & Bioquim Fungos & Protozoario, Sao Paulo, BrazilWeb of Scienc

Toxocara Seropositivity, Atopy and Wheezing in Children Living in Poor Neighbourhoods in Urban Latin American

Background Toxocara canis and T. cati are parasites of dogs and cats, respectively, that infect humans and cause human toxocariasis. Infection may cause asthma-like symptoms but is often asymptomatic and is associated with a marked eosinophilia. Previous epidemiological studies indicate that T. canis infection may be associated with the development of atopy and asthma. Objectives To investigate possible associations between Toxocara spp. seropositivity and atopy and childhood wheezing in a population of children living in non-affluent areas of a large Latin American city. Methods The study was conducted in the city of Salvador, Brazil. Data on wheezing symptoms were collected by questionnaire, and atopy was measured by the presence of aeroallergen-specific IgE (sIgE). Skin prick test (SPT), total IgE and peripheral eosinophilia were measured. Toxocara seropositivity was determined by the presence of anti-Toxocara IgG antibodies, and intestinal helminth infections were determined by stool microscopy. Findings Children aged 4 to 11 years were studied, of whom 47% were seropositive for anti-Toxocara IgG; eosinophilia >4% occurred in 74.2% and >10% in 25.4%; 59.6% had elevated levels of total IgE; 36.8% had sIgE≥0.70 kU/L and 30.4% had SPT for at least one aeroallergen; 22.4% had current wheezing symptoms. Anti-Toxocara IgG was positively associated with elevated eosinophils counts, total IgE and the presence of specific IgE to aeroallergens but was inversely associated with skin prick test reactivity. Conclusion The prevalence of Toxocara seropositivity was high in the studied population of children living in conditions of poverty in urban Brazil. Toxocara infection, although associated with total IgE, sIgE and eosinophilia, may prevent the development of skin hypersensitivity to aeroallergens, possibly through increased polyclonal IgE and the induction of a modified Th2 immune reaction

Babassu aqueous extract (BAE) as an adjuvant for T helper (Th)1-dependent immune responses in mice of a Th2 immune response-prone strain

<p>Abstract</p> <p>Background</p> <p>The aqueous extract of a Brazilian palm-tree fruit - the babassu - (BAE) exerts a clear immunostimulative activity <it>in vivo</it>. In the present work, the possibility that BAE can promote Th1 immune responses in mice of a Th2 immune response-prone strain - the BALB/c was investigated. BAE itself, and preparations consisting of <it>Leishmania amazonensis </it>promastigote extract (LE), adsorbed or not to Al(OH)₃, and in the presence or not of BAE, were used as immunogens. LE and Al(OH)₃have been shown to preferentially elicit Th2 immune responses.</p> <p>Results</p> <p>The addition of BAE to LE-containing immunogenic preparations, adsorbed or not to Al(OH)₃, clearly promoted the <it>in vitro </it>production of interferon γ (IFN-γ), a major Th1-dependent cytokine, and not of interleukin (IL-)4 (a Th2-dependent cytokine), by LE-stimulated splenocytes of immunized BALB/c mice. It also promoted the <it>in vivo </it>formation of IgG2a anti-LE antibodies. However, immunization with LE by itself led to an increased production of IL-4 by LE-stimulated splenocytes, and this production, albeit not enhanced, was not reduced by the addition of BAE to the immunogen. On the other hand, the IL-4 production by LE-stimulated splenocytes was significantly lower in mice immunized with a preparation containing Al(OH)₃-adsorbed LE and BAE than in mice immunized with the control preparation of Al(OH)₃-adsorbed LE without BAE. Moreover, an increased production of IFN-γ, and not of IL-4, was observed in the culture supernatants of splenocytes, from BAE-immunized mice, which were <it>in vitro </it>stimulated with BAE or which received no specific <it>in vitro </it>stimulus. No differences in IL-10 (an immunoregulatory cytokine) levels in the supernatants of splenocytes from mice that were injected with BAE, in relation to splenocytes from control mice, were observed. The spontaneous <it>ex vivo </it>production of NO by splenocytes of mice that had been injected with BAE was significantly higher than the production of NO by splenocytes of control mice.</p> <p>Conclusions</p> <p>Based on the results described above, BAE, or biologically active molecules purified from it, should be further investigated as a possible adjuvant, in association or not with aluminium compounds, for the preferential induction of Th1-dependent immune responses against different antigens in distinct murine strains and animal species.</p

Risk factors for asthma and allergy associated with urban migration: background and methodology of a cross-sectional study in Afro-Ecuadorian school children in Northeastern Ecuador (Esmeraldas-SCAALA Study)

BACKGROUND: Asthma and allergic diseases are becoming increasingly frequent in children in urban centres of Latin America although the prevalence of allergic disease is still low in rural areas. Understanding better why the prevalence of asthma is greater in urban migrant populations and the role of risk factors such as life style and environmental exposures, may be key to understand what is behind this trend. METHODS/DESIGN: The Esmeraldas-SCAALA (Social Changes, Asthma and Allergy in Latin America) study consists of cross-sectional and nested case-control studies of school children in rural and urban areas of Esmeraldas Province in Ecuador. The cross-sectional study will investigate risk factors for atopy and allergic disease in rural and migrant urban Afro-Ecuadorian school children and the nested case-control study will examine environmental, biologic and social risk factors for asthma among asthma cases and non-asthmatic controls from the cross-sectional study. Data will be collected through standardised questionnaires, skin prick testing to relevant aeroallergen extracts, stool examinations for parasites, blood sampling (for measurement of IgE, interleukins and other immunological parameters), anthropometric measurements for assessment of nutritional status, exercise testing for assessment of exercise-induced bronchospasm and dust sampling for measurement of household endotoxin and allergen levels. DISCUSSION: The information will be used to identify the factors associated with an increased risk of asthma and allergies in migrant and urbanizing populations, to improve the understanding of the causes of the increase in asthma prevalence and to identify potentially modifiable factors to inform the design of prevention programmes to reduce the risk of allergy in urban populations in Latin America