Role of airway smooth muscle cell phenotypes in airway tone and obstruction in guinea pig asthma model

Abstract

Background Airway obstruction (AO) in asthma is driven by airway smooth muscle (ASM) contraction. AO can be induced extrinsically by direct stimulation of ASM with contractile agonists as histamine, or by indirect provocation with antigens as ovalbumin, while the airway tone is dependent on intrinsic mechanisms. The association of the ASM phenotypes involved in different types of AO and airway tone in guinea pigs was evaluated. Methods Guinea pigs were sensitized to ovalbumin and challenged with antigen. In each challenge, the maximum OA response to ovalbumin was determined, and before the challenges, the tone of the airways. At third challenge, airway responsiveness (AR) to histamine was evaluated and ASM cells from trachea were disaggregated to determinate: (a) by flow cytometry, the percentage of cells that express transforming growth factor-β1 (TGF-β1), interleukin-13 (IL-13) and sarco-endoplasmic Ca2+ ATPase-2b (SERCA2b), (b) by RT-PCR, the SERCA2B gene expression, (c) by ELISA, reduced glutathione (GSH) and, (d) Ca2+ sarcoplasmic reticulum refilling rate by microfluorometry. Control guinea pig group received saline instead ovalbumin. Results Antigenic challenges in sensitized guinea pigs induced indirect AO, AR to histamine and increment in airway tone at third challenge. No relationship was observed between AO induced by antigen and AR to histamine with changes in airway tone. The extent of antigen-induced AO was associated with both, TGF-β1 expression in ASM and AR degree. The magnitude of AR and antigen-induced AO showed an inverse correlation with GSH levels in ASM. The airway tone showed an inverse association with SERCA2b expression. Conclusions Our data suggest that each type of AO and airway tone depends on different ASM phenotypes: direct and indirect AO seems to be sensitive to the level of oxidative stress; indirect obstruction induced by antigen appears to be influenced by the expression of TGF-β1 and the SERCA2b expression level plays a role in the airway tone.

High Stretch Modulates cAMP/ATP Level in Association with Purine Metabolism via miRNA–mRNA Interactions in Cultured Human Airway Smooth Muscle Cells

“…In this study, however, we found that high stretch modulated intracellular levels of cAMP/ATP via miRNA-mRNA, particularly miR-370-5p-PDE4D/AK7 interactions. In addition, we found that miR-370-5p did impact cell stiffness, but not the cell stiffness reduction induced by β-agonist, suggesting that high stretch through miR-370-5p-PDE4D interaction is a mechanical modulator of bronchial airway tone [62] In addition to the modulation of airway tone through contraction/relaxation, ASMCs also modulate airway inflammation by secreting or expressing a wide array of immunomodulatory mediators in response to extracellular stimuli such as high stretch [63]. For example, mechanical stress can induce more pro-inflammatory mediators including IL-1β, IL-8, IL-6, and TNF-α in the distal air spaces of the lung [64].…”

IgE-dependent human basophil responses are inversely associated with the sarcoplasmic reticulum Ca2+-ATPase (SERCA)

“…Conversely, Qaisar et al. ( 43 ) also reported reduced SERCA expressions in asthma and, in a guinea pig model of asthma, reduced SERCA2b expression in airway smooth muscle cells was recently reported to correlate with intrinsic airway baseline tone ( 44 ). The proinflammatory cytokines, TNFα and IL-13, which are heavily implicated in asthma severity, were shown to decrease SERCA2 expressions in human airway smooth muscle cells ( 23 ).…”