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OVA Challenge (ovum + challenge)
Selected AbstractsNeonatal exposure to staphylococcal superantigen improves induction of oral tolerance in a mouse model of airway allergyEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2009Anna Lönnqvist Abstract The hygiene hypothesis suggests that lack of microbial stimulation in early infancy may lead to allergy, but it has been difficult to identify particular protective microbial exposures. We have observed that infants colonised in the first week(s) of life with Staphylococcus aureus have lower risk of developing food allergy. As many S. aureus strains produce superantigens with T-cell stimulating properties, we here investigate whether neonatal mucosal exposure to superantigen could influence the capacity to develop oral tolerance and reduce sensitisation and allergy. BALB/c mice were exposed to staphylococcal enterotoxin A (SEA) as neonates and fed with OVA as adults, prior to sensitisation and i.n. OVA challenge. Our results show that SEA pre-treated mice are more efficiently tolerised by OVA feeding, as shown by lower lung-cell infiltration and antigen-specific IgE response in the SEA pre-treated mice, compared with sham-treated mice. This was not due to deletion or anergy of lymphocytes by SEA treatment, because the SEA pre-treated mice that were fed with PBS showed similar inflammatory response as the sham-treated PBS-fed mice. Our results suggest that strong T-cell activation in infancy conditions the mucosal immune system and promotes development of oral tolerance. [source] Pharmacology and immunological actions of a herbal medicine ASHMITM on allergic asthmaPHYTOTHERAPY RESEARCH, Issue 7 2010Tengfei Zhang Abstract Allergic asthma is a chronic and progressive inflammatory disease for which there is no satisfactory treatment. Studies reported tolerability and efficacy of an anti-asthma herbal medicine intervention (ASHMI) for asthma patients, developed from traditional Chinese medicine. To investigate the pharmacological actions of ASHMI on early- and late-phase airway responses (EAR and LAR), Ovalbumin (OVA)-sensitized mice received 6 weeks of ASHMI treatment beginning 24,h following the first intratracheal OVA challenge. EAR were determined 30,min following the fourth challenge and LAR 48,h following the last challenge. ASHMI effects on cytokine secretion, murine tracheal ring contraction and human bronchial smooth muscle cell prostaglandin (PG) production were also determined. ASHMI abolished EAR, which was associated with significantly reduced histamine, leukotriene C4, and OVA-specific IgE levels, as well as LAR, which was associated with significantly reduced bronchoalveolar lavage fluid (BALF) eosinophils, decreased airway remodeling, and lower Th2 cytokine levels in BALF and splenocyte cultures. Furthermore, ASHMI inhibited contraction of murine tracheal rings and increased production of the potent smooth muscle relaxer PGI2. ASHMI abrogation of allergic airway responses is associated with broad effects on asthma pathological mechanisms. Copyright © 2009 John Wiley & Sons, Ltd. [source] Neurokinin-1 receptor activation induces reactive oxygen species and epithelial damage in allergic airway inflammationCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2007J. Springer Summary Background An induction of reactive oxygen species (ROS) is characteristic for inflammation but the exact pathways have not been identified for allergic airway diseases so far. Objective The aim of this study was to characterize the role of the tachykinin NK-1 receptor on ROS production during allergen challenge and subsequent inflammation and remodelling. Methods Precision-cut lung slices of ovalbumin (OVA)-sensitized mice were cultivated and ROS-generation in response to OVA challenge (10 ,g/mL) was examined by the 2,,7,-dichloroflourescein-diacetate method. Long-term ROS effects on epithelial proliferation were investigated by 5-bromo-2,-deoxyuridine incorporation (72 h). In vivo, the results were validated in OVA-sensitized animals which were treated intra-nasally with either placebo, the tachykinin neurokinin 1 (NK-1) receptor antagonist SR 140333 or the anti-oxidant N -acetylcystein (NAC) before allergen challenge. Inflammatory infiltration and remodelling were assessed 48 h after allergen challenge. Results ROS generation was increased by 3.7-fold, which was inhibited by SR 140333. [Sar9,Met11(O2)]-Substance P (5 nm) caused a tachykinin NK-1 receptor-dependent fourfold increase in ROS generation. Epithelial proliferation was decreased by 68% by incubation with [Sar9,Met11(O2)]-SP over 72 h. In-vivo, treatment with SR 140333 and NAC reduced epithelial damage (91.4% and 76.8% vs. placebo, respectively, P<0.01) and goblet cell hyperplasia (67.4% and 50.1% vs. placebo, respectively, P<0.05), and decreased inflammatory cell influx (65.3% and 45.3% vs. placebo, respectively, P<0.01). Conclusion Allergen challenge induces ROS in a tachykinin NK-1 receptor-dependent manner. Inhibition of the tachykinin NK-1 receptor reduces epithelial damage and subsequent remodelling in vivo. Therefore, patients may possibly benefit from treatment regime that includes radical scavengers or tachykinin NK-1 receptor antagonists. [source] Dose-dependent effects of endotoxins on allergen sensitization and challenge in the mouseCLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2004C. Delayre-Orthez Summary Background Levels of endotoxins greatly differ according to environmental settings. Objective To study the effect of lipopolysaccharide (LPS) at increasing doses (0.1,1000 ng) on allergen sensitization and challenge in the mouse. Methods Mice were sensitized systemically and challenged locally with ovalbumin (OVA) in the presence or absence of LPS. Inflammation was assessed by determining total and differential cell counts and T-helper type 2 (Th)2 cytokine (IL-4 and IL-5) levels in bronchoalveolar lavage fluid (BALF). Total and OVA-specific IgE levels were quantified in serum. Airway hyper-responsiveness (AHR) was assessed by whole-body barometric plethysmography. Results Administered prior to sensitization, LPS at 100 or 1000 ng dose-dependently decreased allergen- induced total and OVA-specific IgE, airway eosinophilia and Th2 cytokines in BALF, without changing AHR. Administered during OVA challenge, LPS at 1 ng (an infra-clinical dose) or 100 ng (a dose triggering neutrophilia) enhanced airway eosinophilia, without affecting IgE levels or AHR. Conclusion Our data clearly demonstrate that exposure to LPS influences allergen-induced IgE production and airway eosinophilia in a time and dose-dependent manner, preventing IgE production and development of eosinophilia when administered during allergen sensitization at high doses, and inducing exacerbation of eosinophilia when administered upon allergen challenge at low doses, including infra-clinical doses. [source] Comparison of glucocorticoid and cysteinyl leukotriene receptor antagonist treatments in an experimental model of chronic airway inflammation in guinea-pigsCLINICAL & EXPERIMENTAL ALLERGY, Issue 1 2004E. A. Leick-maldonado Abstract Background Leukotriene receptor antagonists have been demonstrated in several studies to possess bronchodilating and anti-inflammatory properties in asthma. However, there are few experimental studies performed to compare the effects of anti-leukotrienes and glucocorticoids, most used anti-inflammatory agents in asthma. In the present study, we evaluated the effects of treatment with dexamethasone or montelukast on eosinophil and mononuclear cell recruitment in an experimental model of allergen-induced chronic airway inflammation in guinea-pigs (GP). Methods GP were submitted to increasing concentrations of aerosols of ovalbumin (OVA) twice a week for 4 weeks. After 2 weeks, animals were treated daily with dexamethasone, montelukast or saline solution. After this period, GP were anaesthetized, tracheostomized, mechanically ventilated and challenged with OVA aerosol. Results Maximal changes of respiratory system resistance and elastance induced by OVA challenge were attenuated by dexamethasone (P<0.001), but not by montelukast treatment. Neither dexamethasone nor montelukast significantly influenced bronchial oedema formation. Dexamethasone but not montelukast induced a decrease in mononuclear cells in airways (P<0.001). Eosinophil infiltration in the bronchial wall was reduced by both dexamethasone and montelukast (P<0.005). Only dexamethasone treatment reduced the levels of exhaled nitric oxide (P<0.025). Conclusion Although leukotriene receptor antagonist treatment reduces eosinophil accumulation induced by multiple antigen challenges, glucocorticoid treatment attenuates both eosinophil and mononuclear cell infiltration. [source] Mycobacterium vaccae administration during allergen sensitization or challenge suppresses asthmatic featuresCLINICAL & EXPERIMENTAL ALLERGY, Issue 8 2003J. J. Smit Summary Background and objective The hygiene hypothesis suggests that a lack of bacterial infections would favour the development of allergic disease. For this reason, bacteria or their components can be used as potential treatment for allergic asthma. We investigated whether heat-killed Mycobacterium vaccae is either able to suppress the induction of allergic asthma or able to suppress already established allergic asthma. Methods Mice were sensitized with ovalbumin (OVA)/alum on days 0 and 14. Thereafter, mice were challenged on days 35, 39 and 42 by inhalation of either OVA or saline aerosols. M. vaccae -treated mice received an injection with 106, 107 or 108 CFU heat-killed M. vaccae on days 0 and 14 or 107 CFU on days 35 and 39. On day 43, the airway responsiveness of the mice to increasing concentrations of methacholine was assessed, blood was withdrawn to measure serum parameters, and lung lavage was performed to detect cytokines and inflammatory cell number. Results Treatment of OVA-sensitized mice with 107 CFU M. vaccae either during sensitization or challenge suppresses airway hyper-responsiveness, airway eosinophilia and IL-5 production after OVA challenge. The increases in OVA-specific serum IgE and in IL-4 by respiratory challenges with OVA were only diminished after M. vaccae treatment (107 CFU) during sensitization. Conclusions Heat-killed M. vaccae prevents allergic and asthmatic manifestations in a mouse model and, more importantly, M. vaccae treatment during challenge suppresses features of asthma, which opens up possibilities for new therapeutic interventions. [source] CD4+ T cells from mice with intestinal immediate-type hypersensitivity induce airway hyperreactivityCLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2007C. Ozdemir Summary Background A subset of food-allergic patients does not only respond clinically with symptoms in the gastro-intestinal tract but also with asthmatic reactions. Objective The aim of this study was to analyse whether CD4+ T cells from mice with intestinal immediate-hypersensitivity reactions to food allergen are involved in the development of experimental asthma. Methods BALB/c mice were intraperitoneally sensitized to ovalbumin (OVA), followed by repeated intra-gastric (i.g.) OVA challenges. Control animals were either sham-sensitized or sham-challenged with phosphate-buffered saline (PBS). Duodenum, jejunum, ileum and colon were histologically examined. CD4+ T cells from mesenteric lymph nodes were transferred from various donor groups into recipient mice that received either OVA or PBS aerosol challenges. Recipients were analysed by measurements of lung function using head-out body-plethysmography and examination of broncho-alveolar lavage and lung histology. Results The highest levels of OVA-specific IgE antibody levels were detected in OVA-sensitized and OVA-challenged mice. Throughout the lower intestinal tract, a marked infiltration with eosinophils was observed, and goblet cell numbers as well as goblet cell area were significantly increased. The villus/crypt ratio was decreased compared with controls. The transfer of CD4+ T cells from mesenteric lymph nodes of OVA-sensitized and OVA-challenged mice triggered airway hyperreactivity and eosinophilic airway inflammation in recipients aerosol challenged with OVA, but not with PBS. Conclusion We conclude that CD4+ T cells from mesenteric lymph nodes of mice with allergen-induced immediate-type hypersensitivity reactions in the gut are able to transfer the phenotype of experimental asthma. [source] | ||||||||||