Food allergy enhances allergic asthma in mice

BackgroundAtopic march refers to the typical transition from a food allergy in early childhood to allergic asthma in older children and adults. However the precise interplay of events involving gut, skin and pulmonary inflammation in this process is not completely understood.ObjectivesTo develop a mouse model of mixed food and respiratory allergy mimicking the atopic march and better understand the impact of food allergies on asthma.MethodsFood allergy to ovalbumin (OVA) was induced through intra-peritoneal sensitization and intra-gastric challenge, and/or a respiratory allergy to house dust mite (HDM) was obtained through percutaneous sensitization and intra-nasal challenges with dermatophagoides farinae (Der f) extract. Digestive, respiratory and systemic parameters were analyzed.ResultsOVA-mediated gut allergy was associated with an increase in jejunum permeability, and a worsening of Der f-induced asthma with stronger airway hyperresponsiveness and pulmonary cell infiltration, notably eosinophils. There was overproduction of the pro-eosinophil chemokine RANTES in broncho-alveolar lavages associated with an enhanced Th2 cytokine secretion and increased total and Der f-specific IgE when the two allergies were present. Both AHR and lung inflammation increased after a second pulmonary challenge.ConclusionGut sensitization to OVA amplifies Der f-induced asthma in mice

Previous food allergy aggravates allergic markers and intestinal damages in a mouse model of asthma

International audienceIncreasing clinical data suggest a link between food allergy and the later development of respiratory allergy. This progression may be triggered by exposures to different allergens but the mechanism implicated remains unknown. This study aimed to identify the impact of a first exposure to food allergen on the development of a new form of allergy caused by exposure to a novel allergen using a mouse model

Consecutive Food and Respiratory Allergies Amplify Systemic and Gut but Not Lung Outcomes in Mice

International audienceEpidemiological data suggest a link between food allergies and the subsequent development of asthma. Although this progression may result from the additional effects of exposure to multiple allergens, whether both allergies amplify each other's effects remains unknown. This study investigated whether oral exposure to food allergens influences the outcomes of subsequent respiratory exposure to an asthma-inducing allergen. Mice were sensitized and orally challenged with wheat (FA) and then exposed to house dust mite (HDM) extract (RA). Immunoglobulin (Ig), histamine, and cytokine levels were assayed by ELISA. Intestinal and lung physiology was assessed. Ig levels, histamine release, and cytokine secretion were higher after exposure to both allergens than after separate exposure to each. Intestinal permeability was higher, although airway hyper-responsiveness and lung inflammation remained unchanged. Exposure to food and respiratory allergens amplifies systemic and gut allergy-related immune responses without any additional effect on lung function and inflammation

Prevention of allergic asthma through Der p 2 peptide vaccination

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Chest physiotherapy enhances detection of Pseudomonas aeruginosa in nonexpectorating children with cystic fibrosis

International audienceLung damage in cystic fibrosis (CF) is strongly associated with lower airway infections. Early treatment of Pseudomonas aeruginosa is recommended. Pathogen detection requires sampling of lower airway secretions, which remains a challenge in nonexpectorating patients. Our hypothesis was that chest physiotherapy would improve the quality of airway secretion samples and increase the rates of pathogens detected in nonexpectorating patients.This prospective multicentre study compared three successive methods for sampling airway secretions applied through the same session: 1) an oropharyngeal swab (OP), 2) a chest physiotherapy session followed by a provoked cough to obtain sputum (CP-SP) and 3) a second oropharyngeal swab collected after chest physiotherapy (CP-OP). Haemophilus influenzae, Staphylococcus aureus and P. aeruginosa growth cultures were assessed. Accuracy tests and an equivalence test were performed to compare the three successive methods of collection.300 nonexpectorating children with CF were included. P. aeruginosa was detected cumulatively in 56 (18.9%) children, and according to the different collection methods in 28 (9.8%), 37 (12.4%) and 44 (14.7%) children by using OP, CP-OP and CP-SP, respectively. Compared with OP, the increased detection rate was +22% for CP-OP (p=0.029) and +57% for CP-SP (p=0.003). CP-SP had the best positive predictive value (86.3%) and negative predictive value (96.0%) for P. aeruginosa compared with the overall detection.The results of this adequately powered study show differences in the rates of pathogens detected according to the sampling method used. Chest physiotherapy enhanced detection of P. aeruginosa in nonexpectorating children with CF

Block Copolymer/DNA Vaccination Induces a Strong Allergen-Specific Local Response in a Mouse Model of House Dust Mite Asthma

<div><p>Background</p><p>Allergic asthma is caused by abnormal immunoreactivity against allergens such as house dust mites among which <i>Dermatophagoides farinae</i> (Der f) is a common species. Currently, immunotherapy is based on allergen administration, which has variable effect from patient to patient and may cause serious side effects, principally the sustained risk of anaphylaxis. DNA vaccination is a promising approach by triggering a specific immune response with reduced allergenicity.</p><p>Objective</p><p>The aim of the study is to evaluate the effects of DNA immunization with Der f1 allergen specific DNA on allergic sensitization, inflammation and respiratory function in mice.</p><p>Methods</p><p>Mice were vaccinated 28 and 7 days before allergen exposure with a Der f1-encoding plasmid formulated with a block copolymer. Asthma was induced by skin sensitization followed by intra-nasal challenges with Der f extract. Total lung, broncho-alveolar lavage (BAL) and spleen cells were analyzed by flow cytometry for their surface antigen and cytokine expression. Splenocytes and lung cell IFN-γ production by CD8+ cells in response to Der f CMH1-restricted peptides was assessed by ELISPOT. IgE, IgG1 and IgG2a were measured in serum by ELISA. Specific bronchial hyperresponsiveness was assessed by direct resistance measurements.</p><p>Results</p><p>Compared to animals vaccinated with an irrelevant plasmid, pVAX-Der f1 vaccination induced an increase of B cells in BAL, and an elevation of IL-10 and IFN-γ but also of IL-4, IL-13 and IL-17 producing CD4+ lymphocytes in lungs and of IL-4 and IL-5 in spleen. In response to CD8-restricted peptides an increase of IFN-γ was observed among lung cells. IgG2a levels non-specifically increased following block copolymer/DNA vaccination although IgE, IgG1 levels and airways resistances were not impacted.</p><p>Conclusions & Clinical Relevance</p><p>DNA vaccination using a plasmid coding for Der f1 formulated with the block copolymer 704 induces a specific immune response in the model of asthma used herein.</p></div

Der f1 and βgal expression assessment.

<p>Five days after the last vaccine injection, Der f1 and βgal gene expression were verified by RT-PCR on skeletal muscle RNA using specific primers (n = 3 per group). This experience was done for both DNA vaccination conditions (10 µg and 5 µg of plasmid preparation).</p

Effect of immunization protocol on BAL inflammation of non asthmatic non vaccinated mice (light grey bar, n = 8), Der f mice (open bar, n = 9), pCMV-βgal (grey bar, n = 7) and pVAX-Der f1 mice (black bar, n = 7) when using 10 µg of DNA.

<p>The total number of cells was determined by cell count on Kova slides. The cellular composition was established by flow cytometry. Results are expressed as absolute number of cells, as the mean and standard deviation for each group. **p<0,01 and *** p<0,001 by Mann Whitney test.</p

Flow cytometry mix for detection of cytokine produced by lung T cells.

<p>Flow cytometry mix for detection of cytokine produced by lung T cells.</p