endothelin-1 and Airway-Remodeling

Icariin (ICA) is the major active ingredient extracted from Chinese herbal medicine Epimedium, which has the effects of improving cardiovascular function, inducing tumor cell differentiation and increasing bone formation. It is still rarely reported that ICA can exert its therapeutic potential in asthma via anti-airway remodeling. The point of the study was to estimate the role of ICA in anti-. airway remodeling and its possible mechanism of action in a mouse ovalbumin. (OVA)-induced asthma model.. Hematoxylin and Eosin Staining were performed for measuring airway remodeling related indicators. ELISA, Western blot and Immunohistochemistr-. y (IHC) were used for analyzing the level of protein. RT-PCR was used for analyzing the level of mRNA.. On days 1 and 8, mice were sensitized to OVA by intraperitoneal injection. From day 16 to day 43, previously sensitized mice were exposed to OVA once daily by nebulizer. Interventions were performed orally with ICA (ICA low, medium and high dose groups) or dexamethasone 1 h prior to each OVA exposure. ICA improves pulmonary function, attenuates pulmonary inflammation and airway remodeling in mice exposed to OVA. Histological and Western blot analysis of the lungs show that ICA suppressed transforming growth factor beta 1 and vascular endothelial growth factor expression. Increase in interleukin 13 and endothelin-1 in serum and bronchoalveolar lavage fluid in OVA-induced asthmatic mice are also decreased by ICA. ICA attenuates airway smooth muscle cell proliferation, as well as key factors in the MAPK/Erk pathway.. The fact that ICA can alleviate OVA-induced asthma at least partly through inhibition of ASMC proliferation via MAPK/Erk pathway provides a solid theoretical basis for ICA as a replacement therapy for asthma. These data reveal the underlying reasons of the use of ICA-rich herbs in Traditional Chinese Medicine to achieve good results in treating asthma.

Topics: Airway Remodeling; Animals; Asthma; Drugs, Chinese Herbal; Endothelin-1; Epimedium; Female; Flavonoids; Humans; Interleukin-13; Mice; Mice, Inbred BALB C; Vascular Endothelial Growth Factor A

Asthma is a chronic inflammatory condition of the airways and patients sensitized to airborne fungi such as Aspergillus fumigatus have more severe asthma. Thickening of the bronchial subepithelial layer is a contributing factor to asthma severity for which no current treatment exists. Airway epithelium acts as an initial defence barrier to inhaled spores, orchestrating an inflammatory response and contributing to subepithelial fibrosis.. We aimed to analyse the production of pro-fibrogenic factors by airway epithelium in response to A fumigatus, in order to propose novel anti-fibrotic strategies for fungal-induced asthma.. We assessed the induction of key pro-fibrogenic factors, TGF-β1, TGF-β2, periostin and endothelin-1, by human airway epithelial cells and in mice exposed to A fumigatus spores or secreted fungal factors.. Aspergillus fumigatus specifically caused production of endothelin-1 by epithelial cells in vitro but not any of the other pro-fibrogenic factors assessed. A fumigatus also induced endothelin-1 in murine lungs, associated with extensive inflammation and airway remodelling. Using a selective endothelin-1 receptor antagonist, we demonstrated for the first time that endothelin-1 drives many features of airway remodelling and inflammation elicited by A fumigatus.. Our findings are consistent with the hypothesis that elevated endothelin-1 levels contribute to subepithelial thickening and highlight this factor as a possible therapeutic target for difficult-to-treat fungal-induced asthma.

Topics: Airway Remodeling; Animals; Aspergillosis; Aspergillus fumigatus; Asthma; Endothelin-1; Humans; Male; Mice; Respiratory Mucosa

During acute bronchoconstriction, the airway epithelium becomes mechanically compressed, as airway smooth muscle contracts and the airway narrows. This mechanical compression activates airway epithelium to promote asthmatic airway remodeling. However, whether compressed airway epithelium can feed back on the cause of bronchoconstriction has remained an open question. Here we examine the potential for epithelial compression to augment proliferation and contraction of airway smooth muscle, and thus potentiate further bronchoconstriction and epithelial compression. Well-differentiated primary human bronchial epithelial (HBE) cells maintained in air-liquid interface culture were mechanically compressed to mimic the effect of bronchoconstriction. Primary human airway smooth muscle (HASM) cells were incubated with conditioned media collected from mechanically compressed HBE cells to examine the effect of epithelial-derived mediators on HASM cell proliferation using an EdU assay and HASM cell contraction using traction microscopy. An endothelin receptor antagonist, PD-145065, was employed to probe the role of HBE cell-derived endothelin-1 on the proliferation and contraction of HASM cells. Conditioned media from compressed HBE cells increased HASM cell proliferation, independent of the endothelin-1 signaling pathway. However, conditioned media from compressed HBE cells significantly increased HASM cell basal contraction and histamine-induced contraction, both of which depended on the endothelin-1 signaling pathway. Our data demonstrate that mechanical compression of bronchial epithelial cells contributes to proliferation and basal contraction of airway smooth muscle cells and that augmented contraction depends on epithelial cell-derived endothelin-1. By means of both airway smooth muscle remodeling and contractility, our findings suggest a causal role of epithelial compression on asthma pathogenesis.

Topics: Airway Remodeling; Asthma; Bronchoconstriction; Cell Proliferation; Cells, Cultured; Endothelin-1; Humans; Muscle Contraction; Muscle, Smooth; Respiratory System; Signal Transduction

The current paradigm describing asthma pathogenesis recognizes the central role of abnormal epithelial function in the generation and maintenance of the disease. However, the mechanisms responsible for the initiation of airway remodeling, which contributes to decreased lung function, remain elusive. Therefore, we aimed to determine the role of altered pulmonary gene expression in disease inception and identify proremodeling mediators.. Using an adenoviral vector, we generated mice overexpressing smad2, a TGF-β and activin A signaling molecule, in the lung. Animals were exposed to intranasal ovalbumin (OVA) without systemic sensitization.. Control mice exposed to inhaled OVA showed no evidence of pulmonary inflammation, indices of remodeling, or airway hyper-reactivity. In contrast, local smad2 overexpression provoked airway hyper-reactivity in OVA-treated mice, concomitant with increased airway smooth muscle mass and peribronchial collagen deposition. Pulmonary eosinophilic inflammation was not evident, and there was no change in serum IgE or IgG1 levels. The profound remodeling changes were not mediated by classical pro-inflammatory Th2 cytokines. However, uric acid and interleukin-1β levels in the lung were increased. Epithelial-derived endothelin-1 and fibroblast growth factor were also augmented in smad2-expressing mice. Blocking endothelin-1 prevented these phenotypic changes.. Innate epithelial-derived mediators are sufficient to drive airway hyper-reactivity and remodeling in response to environmental insults in the absence of overt Th2-type inflammation in a model of noneosinophilic, noninflammed types of asthma. Targeting potential asthma therapies to epithelial cell function and modulation of locally released mediators may represent an effective avenue for therapeutic design.

Topics: Airway Remodeling; Animals; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; Endothelin-1; Female; Gene Expression; Inflammation Mediators; Mice; Mice, Transgenic; Muscle, Smooth; Ovalbumin; Respiratory Mucosa; Smad2 Protein

We examined the contribution of p70 ribosomal S6 kinase (p70S6K) to airway smooth muscle hypertrophy, a structural change found in asthma. In human airway smooth muscle cells, transforming growth factor (TGF)-beta, endothelin-1, and cardiotrophin-1 each induced phosphorylation of p70S6K and ribosomal protein S6 while increasing cell size, total protein synthesis, and relative protein abundance of alpha-smooth muscle actin and SM22. Transfection of myocytes with siRNA against either p70S6K or S6, or infection with retrovirus encoding a kinase-dead p70S6K, reduced cell size and protein synthesis but had no effect on contractile protein expression per mg total protein. Infection with a retrovirus encoding a constitutively active, rapamycin-resistant (RR) p70S6K increased cell size but not contractile protein expression. siRNA against S6 decreased cell size in myocytes expressing RR p70S6K. Finally, TGF-beta treatment, but not RR p70S6K expression, increased KCl-induced fractional shortening. Together, these data suggest that p70S6K activation is both required and sufficient for airway smooth muscle cell size enlargement but not contractile protein expression. Further, ribosomal protein S6 is required for p70S6K-mediated cell enlargement. Finally, we have shown for the first time in a functional cell system that p70S6K-mediated myocyte enlargement alone, without preferential contractile protein expression, is insufficient for increased cell shortening.

Topics: Airway Remodeling; Animals; Asthma; Cell Enlargement; Cells, Cultured; Contractile Proteins; Cytokines; Disease Models, Animal; Endothelin-1; Enzyme Activation; Humans; Hypertrophy; Lung; Mice; Mice, Inbred BALB C; Microfilament Proteins; Muscle Contraction; Muscle Proteins; Muscle, Smooth; Mutation; Myocytes, Smooth Muscle; Ovalbumin; Phenotype; Phosphorylation; Potassium Chloride; Ribosomal Protein S6; Ribosomal Protein S6 Kinases, 70-kDa; RNA Interference; Transduction, Genetic; Transforming Growth Factor beta