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In humans and in mice, maternal allergy predisposes offspring to development of allergy. In murine models, increased levels of maternal β-glucosylceramides are both necessary and sufficient for the development of allergic predisposition in offspring. Furthermore, increased numbers of CD11b+ dendritic cell subsets in the offspring of allergic mothers are associated with allergic predisposition. In vitro, β-glucosylceramides increase CD11b+ dendritic cell subset numbers through increased PKCδ signaling, but it is not known if enhanced PKCδ signaling in dendritic cells is required in vivo. We demonstrate that dendritic cell–specific deletion of PKCδ prevents the β-glucosylceramide–induced increase in CD11b+ dendritic cell subset numbers both in vitro as well as in vivo in the fetal liver of offspring of mothers injected with β-glucosylceramides. Furthermore, dendritic cell–specific deletion of PKCδ in offspring prevents the maternal allergy–induced increase in CD11b+ dendritic cell subsets and decreases allergen-induced interleukin-5 and eosinophilia in lungs of offspring. However, loss of PKCδ in dendritic cells did not prevent development of allergen-specific IgE. Our study provides mechanistic insight into the function of PKCδ in the origins of allergic disease beginning in utero as well as in the development of postnatal allergic lung inflammation. [ABSTRACT FROM AUTHOR]

Epidemiological studies demonstrate that maternal obesity and maternal allergy are major risk factors for asthma in offspring. However, the impact of maternal allergy and obesity on offspring lung insulin signaling and allergen responsiveness is not known. To evaluate this, allergic and nonallergic female mice were fed a high-fat diet or low-fat diet from 7 wk before pregnancy until weaning. Neonatal pups were allergen-sensitized and allergen-challenged and then were assessed for obesity, insulin signaling, and allergic inflammation. Compared with pups of nonobese nonallergic mothers, allergen-challenged pups of obese nonallergic mothers, nonobese allergic mothers, and obese allergic mothers had bronchoalveolar lavage (BAL) eosinophilia, with the pups of obese allergic mothers having the highest BAL eosinophilia. These pups also had lower insulin-induced lung AKT phosphorylation, indicating a decrease in lung parenchymal insulin sensitivity. In cross-fostering experiments, allergen-challenged pups exposed to both pre- and postnatal obese allergic mothers had the highest level of BAL eosinophilia. Maternal obesity or allergy increased offspring serum allergen-specific IgE and interleukin-5 that was highest when the mother was both obese and allergic. Also, allergen-challenged pups exposed to both pre- and postnatal obese allergic mothers had the highest level of interleukin-5. In summary, offspring born to obese allergic mothers have decreased lung insulin sensitivity and increased lung allergic inflammation. Interestingly, our data also demonstrate that there is both a pregnancy and postpregnancy aspect of maternal allergy and obesity that enhances allergen responsiveness in offspring. [ABSTRACT FROM AUTHOR]

Summary: Food allergy can be life‐threatening and often develops early in life. In infants and children, loss‐of‐function mutations in skin barrier genes associate with food allergy. In a mouse model with skin barrier mutations (Flakey Tail, FT+/− mice), topical epicutaneous sensitization to a food allergen peanut extract (PNE), an environmental allergen Alternaria alternata (Alt) and a detergent induce food allergy and then an oral PNE‐challenge induces anaphylaxis. Exposures to these allergens and detergents can occur for infants and children in a household setting. From the clinical and preclinical studies of neonates and children with skin barrier mutations, early oral exposure to allergenic foods before skin sensitization may induce tolerance to food allergens and thus protect against development of food allergy. In the FT+/− mice, oral food allergen prior to skin sensitization induce tolerance to food allergens. However, when the skin of FT+/− pups are exposed to a ubiquitous environmental allergen at the time of oral consumption of food allergens, this blocks the induction of tolerance to the food allergen and the mice can then be skin sensitized with the food allergen. The development of food allergy in neonatal FT+/− mice is mediated by altered skin responses to allergens with increases in skin expression of interleukin 33, oncostatin M and amphiregulin. The development of neonate food allergy is enhanced when born to an allergic mother, but it is inhibited by maternal supplementation with α‐tocopherol. Moreover, preclinical studies suggest that food allergen skin sensitization can occur before manifestation of clinical features of atopic dermatitis. Thus, these parameters may impact design of clinical studies for food allergy, when stratifying individuals by loss of skin barrier function or maternal atopy before offspring development of atopic dermatitis. [ABSTRACT FROM AUTHOR]

Food allergy (FA) is estimated to impact up to 10% of the population and is a growing health concern. FA results from a failure in the mucosal immune system to establish or maintain immunological tolerance to innocuous dietary antigens, IgE production, and the release of histamine and other mediators upon exposure to a food allergen. Of the different FAs, peanut allergy has the highest incidence of severe allergic responses, including systemic anaphylaxis. Despite the recent FDA approval of peanut oral immunotherapy and other investigational immunotherapies, a loss of protection following cessation of therapy can occur, suggesting that these therapies do not address the underlying immune response driving FA. Our lab has shown that liver-directed gene therapy with an adeno-associated virus (AAV) vector induces transgene product-specific regulatory T cells (Tregs), eradicates pre-existing pathogenic antibodies, and protects against anaphylaxis in several models, including ovalbumin induced FA. In an epicutaneous peanut allergy mouse model, the hepatic AAV co-expression of four peanut antigens Ara h1, Ara h2, Ara h3, and Ara h6 together or the single expression of Ara h3 prevented the development of a peanut allergy. Since FA patients show a reduction in Treg numbers and/or function, we believe our approach may address this unmet need. [ABSTRACT FROM AUTHOR]

Pulmonary eosinophilia is one of the most consistent hallmarks of asthma. Infiltration of eosinophils into the lung in experimental asthma is dependent on the adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells. Ligation of VCAM-1 activates endothelial cell NADPH oxidase, which is required for VCAM-1-dependent leukocyte migration in vitro. To examine whether endothelial-derived NADPH oxidase modulates eosinophil recruitment in vivo, mice deficient in NADPH oxidase (CYBB mice) were irradiated and received wild-type hematopoietic cells to generate chimeric CYBB mice. In response to ovalbumin (OVA) challenge, the chimeric CYBB mice had increased numbers of eosinophils bound to the endothelium as well as reduced eosinophilia in the lung tissue and bronchoalveolar lavage. This occurred independent of changes in VCAM-1 expression, cytokine/chemokine levels (IL-5, IL-10, IL-13, IFN[gamma] or eotaxin), or numbers of T cells, neutrophils, or mononuclear cells in the lavage fluids or lung tissue of OVA-challenged mice. Importantly, the OVA-challenged chimeric CYBB mice had reduced airway hyperresponsiveness (AHR). The AHR in OVA-challenged chimeric CYBB mice was restored by bypassing the endothelium with intratracheal administration of eosinophils. These data suggest that VCAM-1 induction of NADPH oxidase in the endothelium is necessary for the eosinophil recruitment during allergic inflammation. Moreover, these studies provide a basis for targeting VCAM-1-dependent signaling pathways in asthma therapies. endothelium; gp91 phox; eosinophils; VCAM-1 doi:10.1152/ajplung.00208.2006

The trafficking of leukocytes from the blood to sites of inflammation is the cumulative result of receptor-ligand-mediated signaling events associated with the leukocytes themselves as well as with the underlying vascular endothelium. Our data show that G[[alpha].sub.i] signaling pathways in the vascular endothelium regulate a critical step required for leukocyte diapedesis. In vivo studies using knockout mice demonstrated that a signaling event in a non-lymphohematopoietic compartment of the lung prevented the recruitment of proinflammatory leukocytes. Intravital microscopy showed that blockade was at the capillary endothelial surface and ex vivo studies of leukocyte trafficking demonstrated that a G[[alpha].sub.i]-signaling event in endothelial cells was required for transmigration. Collectively, these data suggest that specific G[[alpha].sub.i2]-mediated signaling between endothelial cells and leukocytes is required for the extravasation of leukocytes and for tissue-specific accumulation. G proteins | inflammation | knockout mice | leukocyte trafficking | pulmonary models