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

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.

Exhaled Breath Condensate—A Non-Invasive Approach for Diagnostic Methods in Asthma

The pathophysiology of asthma has been intensively studied, but its underlying mechanisms such as airway inflammation, control of airway tone, and bronchial reactivity are still not completely explained. There is an urgent need to implement novel, non-invasive diagnostic tools that can help to investigate local airway inflammation and connect the molecular pathways with the broad spectrum of clinical manifestations of asthma. The new biomarkers of different asthma endotypes could be used to confirm diagnosis, predict asthma exacerbations, or evaluate treatment response. In this paper, we briefly describe the characteristics of exhaled breath condensate (EBC) that is considered to be an interesting source of biomarkers of lung disorders. We look at the composition of EBC, some aspects of the collection procedure, the proposed biomarkers for asthma, and its clinical implications. We also indicate the limitations of the method and potential strategies to standardize the procedure of EBC collection and analytical methods.

Comparative Genomic and Network Analysis of nNOS by Using Different Bioinformatics Approaches

Introduction: Nitric oxide (NO) is a diatomic free radical gaseous molecule that is formed from L-arginine through NOS (Nitric oxide synthase) catalyzed reaction. NO controls vascular tone (hence blood pressure), insulin secretion, airway tone, and peristalsis and is involved in angiogenesis (growth of new blood vessels) and in the development of the nervous system. In the CNS, NO is an important messenger molecule, which is involved in various major functions in the brain. NOS has been classified into three isoforms which include nNOS (neuronal NOS), eNOS (endothelial NOS), and iNOS (inducible NOS). NOS1 is localized on chromosome 12, consisting of 1434 amino acids and 161 KDa molecular weight. nNOS is involved in synaptic transmission, regulating the tone of smooth muscles, penile erection. We studied NOS1 gene and protein network analysis through in silico techniques as human nNOS sequence was fetched from GenBank, and its homologous sequences were retrieved through BLAST search. Moreover, the results of this study exploit the role of NOS1 in various pathways, which provide ways to regulate it in various neurodegenerative diseases. Background: Previous research has revealed the role of Nitric Oxide (NO) formed from L-arginine through NOS (Nitric Oxide Synthase) as a physiological inter/intracellular messenger in the central as well as the peripheral nervous system. The diverse functions of NOS include insulin secretion, airway tone, vascular tone regulation, and in the brain, it is involved in differentiation, development, synaptic plasticity, and neurosecretion. Objective: The objective of this study is to unravel the role of neuronal Nitric Oxide Synthase (nNOS) in different pathways and its involvement as a therapeutic target in various neurodegenerative disorders, which can surely provide ways to regulate its activity in different aspects. Materials and Methods: In this study, we employed various bioinformatics tools and databases, initiating the study by fetching the neuronal Nitric Oxide Synthase (nNOS) sequence(GenBank) to find its homologous sequences(BLAST) and then exploring its physical properties and post-translational modifications, enhancing the research by network analysis(STRING), leading to its functional enrichment(Panther). Results : The results positively support the hypothesis of its role in various pathways related to neurodegeneration., Its interacting partners are the probable therapeutic targets of various neurodegenerative diseases focusing on specifically multi-target analysis. Conclusion: This study considered the evolutionary trend of physical, chemical, and biological properties of NOS1 through different phyla. The neuronal Nitric Oxide Synthase (nNOS), being one of the three isoforms of NOS (Nitric Oxide Synthase), is found to be involved in more pathways than just forming Nitric Oxide. This research provides the base for further neurological research.

Long-acting muscarinic antagonists and small airways: which link?

Involvement of small airways, those of less than 2 mm in internal diameter, is present in all stages of asthma and contributes substantially to the pathophysiologic expression of asthma. Therefore, small airways are increasingly viewed as a potential target in optimal asthma control. Airway tone, which is increased in asthma, is mainly controlled by the vagus nerve that releases acetylcholine (ACh) and activates muscarinic ACh receptors (mAChRs) post-synaptically on airway smooth muscle (ASM). In small airways, M3 mAChRs are expressed, but there is no vagal innervation. Non-neuronal ACh released from the epithelial cells that may express choline acetyltransferase (ChAT) in response to inflammatory stimuli, as well as from other structural cells in the airways, including fibroblasts and mast cells, can activate these receptors. By antagonizing M3 mAChR, the contraction of the ASM is prevented and, potentially, local inflammation can be reduced and the progression of remodeling may be affected. In fact, ACh also contributes to inflammation and remodeling of the airways and regulates the growth of ASM. Several experimental studies have demonstrated the potential benefit derived from the use of mAChR antagonists, mainly long-acting mAChR antagonists (LAMAs), on small airways in asthma. However, there are several confounding factors that may cause a wrong estimation of the relationship between LAMAs and small airways in asthma.

Different airway smooth muscle cells phenotypes are involved in intrinsic and extrinsic obstruction in guinea pig asthma model

Background: Airway obstruction in asthma is driven by airway smooth muscle (ASM) contraction. Airway obstruction can be induced extrinsically by direct stimulation of ASM with contractile agonists or by indirect provocation with antigens, while the airway baseline tone is dependent on intrinsic obstruction. The ASM phenotypes involved in all types of obstruction seem to be related.Methods: To determination the associations of the ASM phenotypes involved in different types of airway obstruction, guinea pigs were sensitized to ovalbumin and repetitively challenged with antigen. At the third challenge, histamine provocation was used to evaluate airway responsiveness (AR), and lung samples were obtained to calculate the airway wall area. ASM cells from the trachea were disaggregated to determine 1) the percentage of cells that expressed transforming growth factor-β1 (TGF-β1), interleukin-13 (IL-13) and sarco-endoplasmic Ca2+ ATPase-2b (SERCA2b) by flow cytometry; 2) SERCA2B gene expression by RT-PCR; 3) the level of reduced glutathione (GSH) by ELISA; and 4) the sarcoplasmic reticulum Ca2+ refilling rate by microfluorometry. The control guinea pig group received only saline instead of ovalbumin. Comparisons were made using t-tests, and the associations were determined using Spearman correlation coefficient analysis.Results: Antigenic challenges induced airway obstruction and progressive incremental changes in airway baseline tone. The AR to histamine and the expression of TGF-β1 in ASM cells was increased in the asthma model. The airway wall mass and expression of IL-13 and SERCA2b in ASM cells were similar between groups. SERCA2B gene expression and GSH levels were reduced in the asthma group. The extent of antigen-induced airway obstruction was directly associated with ASM cell TGF-β1 expression and the degree of AR. The magnitude of AR and antigen-induced airway obstruction showed an inverse correlation with GSH levels. The airway baseline tone showed an inverse association with SERCA2b expression. No relationship was observed between direct or indirect airway obstruction and the airway tone. After caffeine withdrawal, the rate of sarcoplasmic reticulum Ca2+ refilling was similar in both groups.Conclusions: Each type of airway obstruction depends on different ASM phenotypes: 1) direct and indirect airway obstruction seems to be sensitive to the level of ASM oxidative stress; 2) indirect obstruction induced by antigen appears to be influenced by the expression of TGF-β1 in ASM; and 3) the SERCA2b expression level in ASM cells plays a role in the intrinsic airway tone.

Magnetic Resonance Imaging and Computed Tomography Imaging Sedation

Magnetic resonance imaging (MRI) and computed tomography (CT) are among the most common procedures to require some level of pediatric sedation. Although painless, they necessitate immobility for adequate imaging quality. Many children can complete these diagnostic procedures without sedation, and this should be encouraged. If sedation medications are needed, propofol is commonly used to administer deep sedation for these procedures given its fast induction and recovery times, but particularly careful ventilation monitoring with capnography is important for the sedation provider who is physically separated from the patient in the MRI suite. Dexmedetomidine use is increasing in both MRI and CT sedation; its advantages are maintenance of airway tone and possible neuroprotective effects, but its disadvantages are longer induction and recovery times. Safety, efficacy, and efficiency should be carefully considered when coordinating sedation care for MRI and CT procedures.