Combined Beta-Agonists and Corticosteroids Do Not Inhibit Extracellular Matrix Protein Production In Vitro

Background. Persistent asthma is characterized by airway remodeling. Whereas we have previously shown that neither β2-agonists nor corticosteroids inhibit extracellular matrix (ECM) protein release from airway smooth muscle (ASM) cells, the effect of their combination is unknown and this forms the rationale for the present study. Methods. ASM cells from people with and without asthma were stimulated with TGFβ1 (1 ng/ml) with or without budesonide (10−8 M) and formoterol (10−10 and 10−8 M), and fibronectin expression and IL-6 release were measured by ELISA. Bronchial rings from nonasthmatic individuals were incubated with TGFβ1 (1 ng/ml) with or without the drugs, and fibronectin expression was measured using immunohistochemistry. Results. Budesonide stimulated fibronectin deposition, in the presence or absence of TGFβ1, and this was partially reversed by formoterol (10−8 M) in both asthmatic and nonasthmatic cells. Budesonide and formoterol in combination failed to inhibit TGFβ-induced fibronectin in either cell type. A similar pattern of expression of fibronectin was seen in bronchial rings. TGFβ1-induced IL-6 release was inhibited by the combination of drugs. Conclusion. Current combination asthma therapies are unable to prevent or reverse remodeling events regulated by ASM cells

Effects of β2 Agonists, Corticosteroids, and Novel Therapies on Rhinovirus-Induced Cytokine Release and Rhinovirus Replication in Primary Airway Fibroblasts

Rhinovirus-(RV-) induced asthma exacerbations account for high asthma-related health costs and morbidity in Australia. The cellular mechanism underlying this pathology is likely the result of RV-induced nuclear-factor-kappa-B-(NF-κB-) dependent inflammation. NF-κB may also be important in RV replication as inhibition of NF-κB inhibits replication of other viruses such as human immunodeficiency virus and cytomegalovirus. To establish the role of NF-κB inhibitors in RV-induced IL- 6 and IL-8 and RV replication, we used pharmacological inhibitors of NF-κB, and steroids and/or β2 agonists were used for comparison. Primary human lung fibroblasts were infected with RV-16 in the presence of NF-κB inhibitors: BAY-117085 and dimethyl fumarate; β2 agonist: salmeterol; and/or corticosteroids: dexamethasone; fluticasone. RV-induced IL-6 and IL-8 and RV replication were assessed using ELISAs and virus titration assays. RV replicated and increased IL-6 and IL-8 release. Salmeterol increased, while dexamethasone and fluticasone decreased RV-induced IL-6 and IL-8 (P<0.05). The NF-κB inhibitor BAY-117085 inhibited only RV-induced IL-6 (P<0.05) and dimethyl fumarate did not alter RV-induced IL-6 and IL-8. Dimethylfumarate increased RV replication whilst other drugs did not alter RV replication. These data suggest that inhibition of NF-κB alone is unlikely to be an effective treatment compared to current asthma therapeutics

LF-15 &amp; T7, Synthetic Peptides Derived from Tumstatin, Attenuate Aspects of Airway Remodelling in a Murine Model of Chronic OVA-Induced Allergic Airway Disease

Background: Tumstatin is a segment of the collagen-IV protein that is markedly reduced in the airways of asthmatics. Tumstatin can play an important role in the development of airway remodelling associated with asthma due to its anti-angiogenic properties. This study assessed the anti-angiogenic properties of smaller peptides derived from tumstatin, which contain the interface tumstatin uses to interact with the aVb3 integrin. Methods: Primary human lung endothelial cells were exposed to the LF-15, T3 and T7 tumstatin-derived peptides and assessed for cell viability and tube formation in vitro. The impact of the anti-angiogenic properties on airways hyperresponsiveness (AHR) was then examined using a murine model of chronic OVA-induced allergic airways disease. Results: The LF-15 and T7 peptides significantly reduced endothelial cell viability and attenuated tube formation in vitro. Mice exposed to OVA+ LF-15 or OVA+T7 also had reduced total lung vascularity and AHR was attenuated compared to mice exposed to OVA alone. T3 peptides reduced cell viability but had no effect on any other parameters. Conclusion: The LF-15 and T7 peptides may be appropriate candidates for use as novel pharmacotherapies due to thei

Novel non-canonical TGF-beta signaling networks:Emerging roles in airway smooth muscle phenotype and function

<p>The airway smooth muscle (ASM) plays an important role in the pathophysiology of asthma and chronic obstructive pulmonary disease (COPD). ASM cells express a wide range of receptors involved in contraction, growth, matrix protein production and the secretion of cytokines and chemokines. Transforming growth factor beta (TGF-beta) is one of the major players in determining the structural and functional abnormalities of the ASM in asthma and COPD. It is increasingly evident that TGF-beta functions as a master switch, controlling a network of intracellular and autocrine signaling loops that effect ASM phenotype and function. In this review, the various elements that participate in non-canonical TGF-beta signaling, including MAPK, PI3K, WNT/beta-catenin, and Ca2+, are discussed, focusing on their effect on ASM phenotype and function. In addition, new aspects of ASM biology and their possible association with non-canonical TGF-beta signaling will be discussed. (C) 2012 Elsevier Ltd. All rights reserved.</p>