Asthma-protective agents in dust from traditional farm environments.

BACKGROUND: Growing up on traditional European or US Amish dairy farms in close contact with cows and hay protects children against asthma, and airway administration of extracts from dust collected from cowsheds of those farms prevents allergic asthma in mice. OBJECTIVES: This study sought to begin identifying farm-derived asthma-protective agents. METHODS: Our work unfolded along 2 unbiased and independent but complementary discovery paths. Dust extracts (DEs) from protective and nonprotective farms (European and Amish cowsheds vs European sheep sheds) were analyzed by comparative nuclear magnetic resonance profiling and differential proteomics. Bioactivity-guided size fractionation focused on protective Amish cowshed DEs. Multiple in vitro and in vivo functional assays were used in both paths. Some of the proteins thus identified were characterized by in-solution and in-gel sodium dodecyl sulfate-polyacrylamide gel electrophoresis enzymatic digestion/peptide mapping followed by liquid chromatography/mass spectrometry. The cargo carried by these proteins was analyzed by untargeted liquid chromatography-high-resolution mass spectrometry. RESULTS: Twelve carrier proteins of animal and plant origin, including the bovine lipocalins Bos d 2 and odorant binding protein, were enriched in DEs from protective European cowsheds. A potent asthma-protective fraction of Amish cowshed DEs (≈0.5% of the total carbon content of unfractionated extracts) contained 7 animal and plant proteins, including Bos d 2 and odorant binding protein loaded with fatty acid metabolites from plants, bacteria, and fungi. CONCLUSIONS: Animals and plants from traditional farms produce proteins that transport hydrophobic microbial and plant metabolites. When delivered to mucosal surfaces, these agents might regulate airway responses.

The Pulmonary Endothelial Glycocalyx Modifications in Glypican 1 Knockout Mice Do Not Affect Lung Endothelial Function in Physiological Conditions.

The endothelial glycocalyx is a dynamic signaling surface layer that is involved in the maintenance of cellular homeostasis. The glycocalyx has a very diverse composition, with glycoproteins, proteoglycans, and glycosaminoglycans interacting with each other to form a mesh-like structure. Due to its highly interactive nature, little is known about the relative contribution of each glycocalyx constituent to its overall function. Investigating the individual roles of the glycocalyx components to cellular functions and system physiology is challenging, as the genetic manipulation of animals that target specific glycocalyx components may result in the development of a modified glycocalyx. Thus, it is crucial that genetically modified animal models for glycocalyx components are characterized and validated before the development of mechanistic studies. Among the glycocalyx components, glypican 1, which acts through eNOS-dependent mechanisms, has recently emerged as a player in cardiovascular diseases. Whether glypican 1 regulates eNOS in physiological conditions is unclear. Herein, we assessed how the deletion of glypican 1 affects the development of the pulmonary endothelial glycocalyx and the impact on eNOS activity and endothelial function. Male and female 5-9-week-old wild-type and glypican 1 knockout mice were used. Transmission electron microscopy, immunofluorescence, and immunoblotting assessed the glycocalyx structure and composition. eNOS activation and content were assessed by immunoblotting; nitric oxide production was assessed by the Griess reaction. The pulmonary phenotype was evaluated by histological signs of lung injury, in vivo measurement of lung mechanics, and pulmonary ventilation. Glypican 1 knockout mice showed a modified glycocalyx with increased glycocalyx thickness and heparan sulfate content and decreased expression of syndecan 4. These alterations were associated with decreased phosphorylation of eNOS at S1177. The production of nitric oxides was not affected by the deletion of glypican 1, and the endothelial barrier was preserved in glypican 1 knockout mice. Pulmonary compliance was decreased, and pulmonary ventilation was unaltered in glypican 1 knockout mice. Collectively, these data indicate that the deletion of glypican 1 may result in the modification of the glycocalyx without affecting basal lung endothelial function, validating this mouse model as a tool for mechanistic studies that investigate the role of glypican 1 in lung endothelial function.

Administration of a Bacterial Lysate to the Airway Compartment Is Sufficient to Inhibit Allergen-Induced Lung Eosinophilia in Germ-free Mice.

The nexus between eosinophils and microbes is attracting increasing attention. We previously showed that airway administration of sterile microbial products contained in dust collected from traditional dairy farms virtually abrogated broncho-alveolar lavage (BAL) eosinophilia and other cardinal asthma phenotypes in allergen-sensitized specific pathogen-free (SPF) mice. Interestingly, comparable inhibition of allergen-induced BAL eosinophilia and promotion of airway barrier integrity were found upon administration of a sterile, pharmacological grade bacterial lysate, OM-85, to the airway compartment of allergen-sensitized SPF mice. Here we asked whether intrinsic properties of airway-delivered microbial products were sufficient to inhibit allergic lung inflammation or whether these effects were mediated by reprogramming of the host microbiota. We compared germ-free (GF) mice and offspring of GF mice associated with healthy mouse gut microbiota and maintained under SPF conditions for multiple generations (Ex-GF mice). These mice were treated intra-nasally with OM-85 and evaluated in the OVA and Alternaria models of allergic asthma focusing primarily on BAL eosinophilia. Levels of allergen-induced BAL eosinophilia were comparable in GF and conventionalized Ex-GF mice. Airway administration of the OM-85 bacterial lysate was sufficient to inhibit allergen-induced lung eosinophilia in both Ex-GF and GF mice, suggesting that host microbiota are not required for the protective effects of bacterial products in these models and local airway exposure to microbial products is an effective source of protection. OM-85-dependent inhibition of BAL eosinophilia in GF mice was accompanied by suppression of lung type-2 cytokines and eosinophil-attracting chemokines, suggesting that OM-85 may work at least by decreasing eosinophil lung recruitment.