The role of natural lipids in an in vivo model of sensitisation to Ber e 1

The prevalence of food allergy is increasing in westernized countries, affecting 5-8% of children and 1-3% of adults. Although innumerous proteins are encountered in normal diets, only few proteins are commonly implicated as food allergens. In this vein, the major focus in allergy studies falls into intrinsic features of allergens; however, it is known that extrinsic factors can play a role in allergic processes. The allergenicity of Ber e 1, the major allergen from Brazil nuts, is well established and it has been shown that natural lipids from Brazil nuts are essential for the development of an immune response towards Ber e 1. The present study aimed to characterize the humoral response induced by recombinant (r)Ber e 1 alone or in the presence of lipids, and to investigate the mechanism(s) by which natural lipids influence the development of an immune response. BALB/c mice were sensitised intraperitoneally with rBer e 1 alone or in the presence of different lipid fractions. It was found that rBer e 1 alone did not induce an immune response and only one specific fraction of Brazil nut lipids (SPC fraction C), composed of a mixture of lipid classes, was able to induce a Th2-type humoral response, with the presence of Ber-specific anaphylactic antibodies, high levels of Ber-specific IgG1, and low levels of Ber-specific IgG2a. CD1-restricted natural killer (NK)T cells recognize lipids and therefore to test the hypothesis that NKT cells may be involved in the response, the sensitisation protocol with rBer e 1 and SPC lipid fraction C was tested in mice lacking these cells (J18 KO mice). These animals presented significantly lower titers of Ber-specific anaphylactic antibodies, Ber-specific IgG1, and total IgE than sensitised wild type mice, indicating that one of the pathways by which lipids triggered an immune response involved NKT cells. In conclusion, the present work found that lipids from Brazil nuts were essential for the development of a Th2-type humoral response to rBer e 1 and that the immune response induced by lipids involved NKT cells

Endotoxin exposure during sensitization to Blomia tropicalis allergens shifts TH2 immunity towards a TH17-mediated airway neutrophilic inflammation: role of TLR4 and TLR2

Experimental evidence and epidemiological studies indicate that exposure to endotoxin lipopolysaccharide (eLPS) or other TLR agonists prevent asthma. We have previously shown in the OVA-model of asthma that eLPS administration during alum-based allergen sensitization blocked the development of lung TH2 immune responses via MyD88 pathway and IL-12/IFN-γ axis. In the present work we determined the effect of eLPS exposure during sensitization to a natural airborne allergen extract derived from the house dust mite Blomia tropicalis (Bt). Mice were subcutaneously sensitized with Bt allergens co-adsorbed onto alum with or without eLPS and challenged twice intranasally with Bt. Cellular and molecular parameters of allergic lung inflammation were evaluated 24 h after the last Bt challenge. Exposure to eLPS but not to ultrapure LPS (upLPS) preparation during sensitization to Bt allergens decreased the influx of eosinophils and increased the influx of neutrophils to the airways. Inhibition of airway eosinophilia was not observed in IFN-γdeficient mice while airway neutrophilia was not observed in IL-17RA-deficient mice as well in mice lacking MyD88, CD14, TLR4 and, surprisingly, TLR2 molecules. Notably, exposure to a synthetic TLR2 agonist (PamCSK4) also induced airway neutrophilia that was dependent on TLR2 and TLR4 molecules. In the OVA model, exposure to eLPS or PamCSK4 suppressed OVA-induced airway inflammation. Our results suggest that B. tropicalis allergens engage TLR4 that potentiates TLR2 signaling. This dual TLR activation during sensitization results in airway neutrophilic inflammation associated with increased frequency of lung TH17 cells. Our work highlight the complex interplay between bacterial products, house dust mite allergens and TLR signaling in the induction of different phenotypes of airway inflammation.State of Sao Paulo Foundation for Research Support (FAPESP - 07/03031-3)State of Sao Paulo Foundation for Research Support (FAPESP - 11/17880-8)CAPES, Brazilian Council of Scientific and Technologic Developmen

The role of natural lipids in an in vivo model of sensitisation to Ber e 1

The prevalence of food allergy is increasing in westernized countries, affecting 5-8% of children and 1-3% of adults. Although innumerous proteins are encountered in normal diets, only few proteins are commonly implicated as food allergens. In this vein, the major focus in allergy studies falls into intrinsic features of allergens; however, it is known that extrinsic factors can play a role in allergic processes. The allergenicity of Ber e 1, the major allergen from Brazil nuts, is well established and it has been shown that natural lipids from Brazil nuts are essential for the development of an immune response towards Ber e 1. The present study aimed to characterize the humoral response induced by recombinant (r)Ber e 1 alone or in the presence of lipids, and to investigate the mechanism(s) by which natural lipids influence the development of an immune response. BALB/c mice were sensitised intraperitoneally with rBer e 1 alone or in the presence of different lipid fractions. It was found that rBer e 1 alone did not induce an immune response and only one specific fraction of Brazil nut lipids (SPC fraction C), composed of a mixture of lipid classes, was able to induce a Th2-type humoral response, with the presence of Ber-specific anaphylactic antibodies, high levels of Ber-specific IgG1, and low levels of Ber-specific IgG2a. CD1-restricted natural killer (NK)T cells recognize lipids and therefore to test the hypothesis that NKT cells may be involved in the response, the sensitisation protocol with rBer e 1 and SPC lipid fraction C was tested in mice lacking these cells (J18 KO mice). These animals presented significantly lower titers of Ber-specific anaphylactic antibodies, Ber-specific IgG1, and total IgE than sensitised wild type mice, indicating that one of the pathways by which lipids triggered an immune response involved NKT cells. In conclusion, the present work found that lipids from Brazil nuts were essential for the development of a Th2-type humoral response to rBer e 1 and that the immune response induced by lipids involved NKT cells.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Role of M2 muscarinic receptor in the airway response to methacholine of mice selected for minimal or maximal acute inflammatory response

Airway smooth muscle constriction induced by cholinergic agonists such as methacholine (MCh), which is typically increased in asthmatic patients, is regulated mainly by muscle muscarinic M3 receptors and negatively by vagal muscarinic M2 receptors. Here we evaluated basal (intrinsic) and allergen-induced (extrinsic) airway responses to MCh. We used two mouse lines selected to respond maximally (AIRmax) or minimally (AIRmin) to innate inflammatory stimuli. We found that in basal condition AIRmin mice responded more vigorously to MCh than AIRmax. Treatment with a specific M2 antagonist increased airway response of AIRmax but not of AIRmin mice. The expression of M2 receptors in the lung was significantly lower in AIRmin compared to AIRmax animals. AIRmax mice developed a more intense allergic inflammation than AIRmin, and both allergic mouse lines increased airway responses to MCh. However, gallamine treatment of allergic groups did not affect the responses to MCh. Our results confirm that low or dysfunctional M2 receptor activity is associated with increased airway responsiveness to MCh and that this trait was inherited during the selective breeding of AIRmin mice and was acquired by AIRmax mice during allergic lung inflammatio