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1.
Identification of the Large-Conductance Ca2+-Regulated Potassium Channel in Mitochondria of Human Bronchial Epithelial Cells.
Sek, A, Kampa, RP, Kulawiak, B, Szewczyk, A, Bednarczyk, P
Molecules (Basel, Switzerland). 2021;(11)
Abstract
Mitochondria play a key role in energy metabolism within the cell. Potassium channels such as ATP-sensitive, voltage-gated or large-conductance Ca2+-regulated channels have been described in the inner mitochondrial membrane. Several hypotheses have been proposed to describe the important roles of mitochondrial potassium channels in cell survival and death pathways. In the current study, we identified two populations of mitochondrial large-conductance Ca2+-regulated potassium (mitoBKCa) channels in human bronchial epithelial (HBE) cells. The biophysical properties of the channels were characterized using the patch-clamp technique. We observed the activity of the channel with a mean conductance close to 285 pS in symmetric 150/150 mM KCl solution. Channel activity was increased upon application of the potassium channel opener NS11021 in the micromolar concentration range. The channel activity was completely inhibited by 1 µM paxilline and 300 nM iberiotoxin, selective inhibitors of the BKCa channels. Based on calcium and iberiotoxin modulation, we suggest that the C-terminus of the protein is localized to the mitochondrial matrix. Additionally, using RT-PCR, we confirmed the presence of α pore-forming (Slo1) and auxiliary β3-β4 subunits of BKCa channel in HBE cells. Western blot analysis of cellular fractions confirmed the mitochondrial localization of α pore-forming and predominately β3 subunits. Additionally, the regulation of oxygen consumption and membrane potential of human bronchial epithelial mitochondria in the presence of the potassium channel opener NS11021 and inhibitor paxilline were also studied. In summary, for the first time, the electrophysiological and functional properties of the mitoBKCa channel in a bronchial epithelial cell line were described.
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2.
Can PBDEs affect the pathophysiologic complex of epithelium in lung diseases?
Albano, GD, Moscato, M, Montalbano, AM, Anzalone, G, Gagliardo, R, Bonanno, A, Giacomazza, D, Barone, R, Drago, G, Cibella, F, et al
Chemosphere. 2020;:125087
Abstract
Brominated flame-retardant (BFRs) exposure promotes multiple adverse health outcomes involved in oxidative stress, inflammation, and tissues damage. We investigated BFR effects, known as polybrominated diphenyl ethers (PBDEs) (47, 99 and 209) in an air-liquid-interface (ALI) airway tissue derived from A549 cell line, and compared with ALI culture of primary human bronchial epithelial cells (pHBEC). The cells, exposed to PBDEs (47, 99 and 209) (0.01-1 μM) for 24 h, were studied for IL-8, Muc5AC and Muc5B (mRNAs and proteins) production, as well as NOX-4 (mRNA) expression. Furthermore, we evaluated tight junction (TJ) integrity by Trans-Epithelial Electrical Resistance (TEER) measurements, and zonula occludens-1 (ZO-1) expression in the cells, and pH variations and rheological properties (elastic G', and viscous G″, moduli) in apical washes of ALI cultures. N-acetylcysteine (NAC) (10 mM) effects were tested in our experimental model of A549 cells. PBDEs (47, 99 and 209) exposure decreased TEER, ZO-1 and pH values, and increased IL-8, Muc5AC, Muc5B (mRNAs and proteins), NOX-4 (mRNA), and rheological parameters (G', G″) in ALI cultures of A549 cell line and pHBEC. NAC inhibited PBDE effects in A549 cells. PBDE inhalation might impairs human health of the lungs inducing oxidative stress, inflammatory response, loss of barrier integrity, unchecked mucus production, as well as altered physicochemical and biological properties of the fluids in airway epithelium. The treatment with anti-oxidants restored the negative effects of PBDEs in epithelial cells.
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3.
Multifaceted activity of N-acetyl-l-cysteine in chronic obstructive pulmonary disease.
Calzetta, L, Matera, MG, Rogliani, P, Cazzola, M
Expert review of respiratory medicine. 2018;(8):693-708
Abstract
N-acetyl-l-cysteine (NAC), a derivative of the naturally occurring amino acid l-cysteine, is a mucolytic agent that may also act as an antioxidant by providing cysteine intracellularly for increased production of glutathione. It is also used for the treatment of acetaminophen overdose. Areas covered: The recent international recommendations for the treatment of chronic obstructive pulmonary disease (COPD) report that NAC, because of its mucolytic activity, reduces acute exacerbation of COPD (AECOPD) with a modest improvement in health status. However, NAC is a pleiotropic drug with heterogeneous pharmacologic characteristics that certainly include mucolytic activity, but also has anti-infective properties and specific antioxidant and anti-inflammatory effects in the airways. Thus, the mechanisms leading to the protective role of this agent against AECOPD need to be adequately addressed. Expert commentary: The protective effect of NAC against AECOPD seems to be related not only to its well-documented mucolytic activity but also to activation of antioxidant pathways, inhibition of pro-oxidant and inflammatory pathways, and modulation of human bronchial tone. Thus, the dogma that NAC acts prevalently as a mucolytic agent is outdated, and the hypothesis that its anti-inflammatory effect is secondary to the antioxidant activity has been rejected.
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4.
N-Acetylcysteine protects human bronchi by modulating the release of neurokinin A in an ex vivo model of COPD exacerbation.
Calzetta, L, Rogliani, P, Facciolo, F, Rinaldi, B, Cazzola, M, Matera, MG
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie. 2018;:1-8
Abstract
AIMS: N-Acetylcysteine (NAC) reduces the risk of exacerbation of chronic obstructive pulmonary disease (COPD). Although NAC also has anti-inflammatory activity, the detailed mechanism leading to its protective role remains to be elucidated. We tested the impact of NAC against the effects of lipopolysaccharide (LPS) in an ex vivo model of COPD exacerbation, and investigated the role of neurokinin A (NKA) in this context. MAIN METHODS Isolated airways from COPD patients were incubated overnight with LPS (100 ng/ml). NAC was tested at concentrations resembling the plasma levels elicited by oral administration of NAC at 200 mg/day (very low dose), 600 mg/day (low dose) and 1.200 mg/day (high dose). KEY FINDINGS NAC at high concentrations normalized the peroxidase activity, H2O2, malondialdehyde (MDA), nitric oxide, glutathione (GSH), total antioxidant capacity (TAC), and interleukin 6 (IL-6) (overall change 34.32% ± 4.22%, P < 0.05 vs. LPS-treated). NAC at low concentrations modulated peroxidase activity, H2O2, MDA, GSH, TAC, and IL-6 (overall change 34.88% ± 7.39%, P < 0.05 vs. LPS-treated). NAC at very-low concentrations was effective on peroxidase activity, H2O2, GSH, and IL-6 (overall change 35.05 ± 7.71%, P < 0.05 vs. LPS-treated). Binary logistic regression analysis indicated that the modulatory effect of NAC on NKA levels was associated with a reduction of pro-oxidant factors and IL-6, and selectively blocking the NK2 receptor abolished such an association. SIGNIFICANCE This study demonstrates that, along with its well-known antioxidant activity, the protective effect of NAC against the detrimental effect of LPS is due to the modulation of NKA and IL-6 levels.
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5.
Human airway epithelial cells investigated by atomic force microscopy: A hint to cystic fibrosis epithelial pathology.
Lasalvia, M, Castellani, S, D'Antonio, P, Perna, G, Carbone, A, Colia, AL, Maffione, AB, Capozzi, V, Conese, M
Experimental cell research. 2016;(1):46-55
Abstract
The pathophysiology of cystic fibrosis (CF) airway disease stems from mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, leading to a chronic respiratory disease. Actin cytoskeleton is disorganized in CF airway epithelial cells, likely contributing to the CF-associated basic defects, i.e. defective chloride secretion and sodium/fluid hypersorption. In this work, we aimed to find whether this alteration could be pointed out by means of Atomic Force Microscopy (AFM) investigation, as roughness and Young's elastic module. Moreover, we also sought to determine whether disorganization of actin cytoskeleton is linked to hypersoption of apical fluid. Not only CFBE41o- (CFBE) cells, immortalized airway epithelial cells homozygous for the F508del CFTR allele, showed a different morphology in comparison with 16HBE14o- (16HBE) epithelial cells, wild-type for CFTR, but also they displayed a lack of stress fibers, suggestive of a disorganized actin cytoskeleton. AFM measurements showed that CFBE cells presented a higher membrane roughness and decreased rigidity as compared with 16HBE cells. CFBE overexpressing wtCFTR became more elongated than the parental CFBE cell line and presented actin stress fibers. CFBE cells absorbed more fluid from the apical compartment. Study of fluid absorption with the F-actin-depolymerizing agent Latrunculin B demonstrated that actin cytoskeletal disorganization increased fluid absorption, an effect observed at higher magnitude in 16HBE than in CFBE cells. For the first time, we demonstrate that actin cytoskeleton disorganization is reflected by AFM parameters in CF airway epithelial cells. Our data also strongly suggest that the lack of stress fibers is involved in at least one of the early step in CF pathophysiology at the levels of the airways, i.e. fluid hypersorption.
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6.
Brain natriuretic peptide modulates calcium homeostasis and epidermal growth factor receptor gene signalling in asthmatic airways smooth muscle cells.
Orlandi, A, Calzetta, L, Doldo, E, Tarquini, C, Matera, MG, Passeri, D
Pulmonary pharmacology & therapeutics. 2015;:51-4
Abstract
The airway epithelium acts as a barrier and provides a critical interface between the body and the external environment. Brain natriuretic peptide (BNP) plays an important role in several bronchial functions, including relaxation. BNP relaxes airways by binding and activating natriuretic peptide receptor-A expressed from the airway epithelium. Although relaxation effect has been extensively investigated, less is known about BNP-regulated intracellular biomolecular pathways leading to bronchial relaxation. To this aim, we investigated BNP effects on gene signalling of airway smooth muscle cells (ASM) obtained from donors with asthma by using a RT(2) profiler™ PCR array. When compared with control, treatment for 2 h with supernatant from BNP-treated (1 μM) bronchial epithelial cells (BEAS-2B) induced in asthmatic ASM cells a rapid reduction of transcription of EGFR and genes involving in actin and calcium homeostasis, as those of Protein kinase C (PKC) and RhoA-ROCK gene pathways. Immunofluorescence and western blotting did not shown any difference comparing control and ASM cells treated with conditioned medium from BNP-treated BEAS-2B. This study provides evidence that the effect of BNP on relaxing bronchial in ASM cells is mediated from epithelium and associates to rapid changes of EGFR and calcium homeostasis-associated gene levels.
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7.
Identification of vitamin C transporters in the human airways: a cross-sectional in vivo study.
Larsson, N, Rankin, GD, Bicer, EM, Roos-Engstrand, E, Pourazar, J, Blomberg, A, Mudway, IS, Behndig, AF
BMJ open. 2015;(4):e006979
Abstract
OBJECTIVES Vitamin C is an important low-molecular weight antioxidant at the air-lung interface. Despite its critical role as a sacrificial antioxidant, little is known about its transport into the respiratory tract lining fluid (RTLF), or the underlying airway epithelial cells. While several vitamin C transporters have been identified, such as sodium-ascorbate cotransporters (SVCT1/2) and glucose transporters (GLUTs), the latter transporting dehydroascorbate, knowledge of their protein distribution within the human lung is limited, in the case of GLUTs or unknown for SVCTs. SETTING AND PARTICIPANTS Protein expression of vitamin C transporters (SVCT1/2 and GLUT1-4) was examined by immunohistochemistry in endobronchial biopsies, and by FACS in airway leucocytes from lavage fluid, obtained from 32 volunteers; 16 healthy and 16 mild asthmatic subjects. In addition, antioxidant concentrations were determined in RTLF. The study was performed at one Swedish centre. PRIMARY AND SECONDARY OUTCOME MEASURES The primary outcome measure was to establish the location of vitamin C transporters in the human airways. As secondary outcome measures, RTLF vitamin C concentration was measured and related to transporter expression, as well as bronchial epithelial inflammatory and goblet cells numbers. RESULTS Positive staining was identified for SVCT1 and 2 in the vascular endothelium. SVCT2 and GLUT2 were present in the apical bronchial epithelium, where SVCT2 staining was predominately localised to goblet cells and inversely related to RTLF vitamin C concentrations. CONCLUSIONS This experimental study is the first to demonstrate protein expression of GLUT2 and SVCT2 in the human bronchial epithelium. A negative correlation between SVCT2-positive goblet cells and bronchial RTLF vitamin C concentrations suggests a possible role for goblet cells in regulating the extracellular vitamin C pool.
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8.
Upregulation of TMEM16A Protein in Bronchial Epithelial Cells by Bacterial Pyocyanin.
Caci, E, Scudieri, P, Di Carlo, E, Morelli, P, Bruno, S, De Fino, I, Bragonzi, A, Gianotti, A, Sondo, E, Ferrera, L, et al
PloS one. 2015;(6):e0131775
Abstract
Induction of mucus hypersecretion in the airway epithelium by Th2 cytokines is associated with the expression of TMEM16A, a Ca2+-activated Cl- channel. We asked whether exposure of airway epithelial cells to bacterial components, a condition that mimics the highly infected environment occurring in cystic fibrosis (CF), also results in a similar response. In cultured human bronchial epithelial cells, treatment with pyocyanin or with a P. aeruginosa culture supernatant caused a significant increase in TMEM16A function. The Ca2+-dependent Cl- secretion, triggered by stimulation with UTP, was particularly enhanced by pyocyanin in cells from CF patients. Increased expression of TMEM16A protein and of MUC5AC mucin by bacterial components was demonstrated by immunofluorescence in CF and non-CF cells. We also investigated TMEM16A expression in human bronchi by immunocytochemistry. We found increased TMEM16A staining in the airways of CF patients. The strongest signal was observed in CF submucosal glands. Our results suggest that TMEM16A expression/function is upregulated in CF lung disease, possibly as a response towards the presence of bacteria in the airways.
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9.
Cigarette smoke causes caspase-independent apoptosis of bronchial epithelial cells from asthmatic donors.
Bucchieri, F, Marino Gammazza, A, Pitruzzella, A, Fucarino, A, Farina, F, Howarth, P, Holgate, ST, Zummo, G, Davies, DE
PloS one. 2015;(3):e0120510
Abstract
BACKGROUND Epidemiologic studies have demonstrated important links between air pollution and asthma. Amongst these pollutants, environmental cigarette smoke is a risk factor both for asthma pathogenesis and exacerbation. As the barrier to the inhaled environment, the bronchial epithelium is a key structure that is exposed to cigarette smoke. OBJECTIVES Since primary bronchial epithelial cells (PBECs) from asthmatic donors are more susceptible to oxidant-induced apoptosis, we hypothesized that they would be susceptible to cigarette smoke-induced cell death. METHODS PBECs from normal and asthmatic donors were exposed to cigarette smoke extract (CSE); cell survival and apoptosis were assessed by fluorescence-activated cell sorting, and protective effects of antioxidants evaluated. The mechanism of cell death was evaluated using caspase inhibitors and immunofluorescent staining for apoptosis-inducing factor (AIF). RESULTS Exposure of PBEC cultures to CSE resulted in a dose-dependent increase in cell death. At 20% CSE, PBECs from asthmatic donors exhibited significantly more apoptosis than cells from non-asthmatic controls. Reduced glutathione (GSH), but not ascorbic acid (AA), protected against CSE-induced apoptosis. To investigate mechanisms of CSE-induced apoptosis, caspase-3 or -9 inhibitors were tested, but these failed to prevent apoptosis; in contrast, CSE promoted nuclear translocation of AIF from the mitochondria. GSH reduced the number of nuclear-AIF positive cells whereas AA was ineffective. CONCLUSION Our results show that PBECs from asthmatic donors are more susceptible to CSE-induced apoptosis. This response involves AIF, which has been implicated in DNA damage and ROS-mediated cell-death. Epithelial susceptibility to CSE may contribute to the impact of environmental tobacco smoke in asthma.
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10.
Effect of dual bronchodilation with QVA149 on cardiac safety in healthy volunteers.
Drollmann, A, Brown, M, Sechaud, R, Perry, S, Hara, H, Jones, I, Febbraro, S
International journal of clinical pharmacology and therapeutics. 2014;(5):369-80
Abstract
OBJECTIVES QVA149 is a dual bronchodilator, containing a fixed-dose combination of the long-acting β2-agonist indacaterol and long-acting muscarinic antagonist glycopyrronium, for the treatment of chronic obstructive pulmonary disease (COPD). Here we assess the potential of QVA149 (440/200 μg) at 4-fold the therapeutic dose for causing cardiac pharmacodynamic (PD) effects. METHODS This double-blind, randomized study estimated the time-matched largest heart rate (HR) change and average HR change (over 24 hours) from baseline for QVA149 vs. placebo in healthy subjects. Similar analyses were done for QVA149 vs. indacaterol 600 μg, glycopyrronium 200 μg, and salmeterol 200 μg. The time-matched and average change from baseline in QT interval corrected for HR using Fridericia's formula (QTcF), effects on serum potassium and blood glucose, pharmacokinetic (PK) parameters, and safety were also assessed. RESULTS Of 50 subjects randomized, 43 completed the study. QVA149, when compared with placebo, showed the time-matched largest mean increase and decrease in HR of 5.69 bpm and -2.51 bpm, respectively, and average HR change from baseline of 0.62 bpm. QVA149 showed no tachycardic potential compared with indacaterol and no relevant tachycardic effect compared with glycopyrronium. No consistent differences were seen in the time-matched largest mean change and average change from baseline in QTcF for QVA149 vs. other treatments. There were no relevant effects of QVA149 on serum potassium and blood glucose. There was no apparent PK/PD relationship between the observed exposures to indacaterol and glycopyrronium in QVA149 on HR and QTcF. There were no deaths or serious adverse events. CONCLUSION Overall, short-term administration of QVA149 showed a good cardiovascular safety and tolerability profile in healthy subjects.