Effects of the root of Platycodon grandiflorum on airway mucin hypersecretion in vivo and platycodin D3 and deapi-platycodin on production and secretion of airway mucin in vitro

We investigated whether aqueous extract of the root of Platycodon grandiflorum A. de Candolle (APG), platycodinD₃ and deapi-platycodin significantly affect the production and secretion of airway mucin using in vivo and in vitro experimental models. Effect of APG was checked on hypersecretion of pulmonary mucin in sulfur dioxide-induced bronchitis in rats. Confluent NCI-H292 cells were pretreated with platycodinD₃ or deapi-platycodin for 30 min and then stimulated with PMA (phorbol 12-myristate 13-acetate) for 24 h. The MUC5AC mucin production and secretion were measured by ELISA. The results were as follows: (1) APG stimulated the secretion of airway mucin in sulfur dioxide-induced bronchitis rat model; (2) platycodinD₃ and deapi-platycodin inhibited the production of MUC5AC mucin induced by PMA from NCI-H292 cells, respectively; (3) however, platycodinD₃ and deapi-platycodin did not inhibit but stimulated the secretion of MUC5AC mucin induced by PMA from NCI-H292 cells, respectively. This result suggests that aqueous extract of P. grandiflorum A. de Candolle and the two natural products derived from it, platycodinD₃ and deapi-platycodin, can regulate the production and secretion of airway mucin and, at least in part, explains the traditional use of aqueous extract of P. grandiflorum A. de Candolle as expectorants in diverse inflammatory pulmonary diseases.     

A Method for Generating Pulmonary Neutrophilia Using Aerosolized Lipopolysaccharide

Acute lung injury (ALI) is a severe disease characterized by alveolar neutrophilia, with limited treatment options and high mortality. Experimental models of ALI are key in enhancing our understanding of disease pathogenesis. Lipopolysaccharide (LPS) derived from gram positive bacteria induces neutrophilic inflammation in the airways and lung parenchyma of mice. Efficient pulmonary delivery of compounds such as LPS is, however, difficult to achieve. In the approach described here, pulmonary delivery in mice is achieved by challenge to aerosolized Pseudomonas aeruginosa LPS. Dissolved LPS was aerosolized by a nebulizer connected to compressed air. Mice were exposed to a continuous flow of LPS aerosol in a Plexiglas box for 10 min, followed by 2 min conditioning after the aerosol was discontinued. Tracheal intubation and subsequent bronchoalveolar lavage, followed by formalin perfusion was next performed, which allows for characterization of the sterile pulmonary inflammation. Aerosolized LPS generates a pulmonary inflammation characterized by alveolar neutrophilia, detected in bronchoalveolar lavage and by histological assessment. This technique can be set up at a small cost with few appliances, and requires minimal training and expertise. The exposure system can thus be routinely performed at any laboratory, with the potential to enhance our understanding of lung pathology.     

Anoctamin 1 in secretory epithelia

Fluid and electrolyte releasing from secretory epithelia are elaborately regulated by orchestrated activity of ion channels. The activity of chloride channel at the apical membrane decides on the direction and the rate of secretory fluid and electrolyte. Chloride-dependent secretion is conventionally associated with intracellular increases in two second messengers, cAMP and Ca²⁺, responding to luminal purinergic and basolateral adrenergic or cholinergic stimulation. While it is broadly regarded that cAMP-dependent Cl⁻ secretion is regulated by cystic fibrosis transmembrane conductance regulator (CFTR), Ca²⁺-activated Cl⁻ channel (CaCC) had been veiled for quite some time. Now, Anoctamin 1 (ANO1 or TMEM16A) confers Ca²⁺-activated Cl⁻ currents. Ano 1 and its paralogs have been actively investigated for multiple functions underlying Ca²⁺-activated Cl⁻ efflux and fluid secretion in a variety of secretory epithelial cells. In this review, we will discuss recent advances in the secretory function and signaling of ANO1 in the secretory epithelia, such as airways, intestines, and salivary glands.     

Evidence that Basolateral But Not Apical Membrane Localization of Outwardly Rectifying Depolarization-Induced Cl− Channel in Airway Epithelia

The rat primary cultured-airway monolayer had been an excellent model for deciphering the ion channel after nystatin permeabilization of its basolateral or apical membrane (Hwang et al., 1996). After apical membrane permeabilization of rat primary cultured-airway monolayer, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS)-sensitive outwardly rectifying depolarization-induced Cl⁻ (BORDIC) currents were observed across the basolateral membrane in symmetrical NMG-Cl solution in this study. No significant Cl⁻ current induced by the application of voltage clamping was observed across the apical membrane in symmetrical NMG-Cl solution after basolateral membrane permeabilization. The halide permeability sequence for BORDIC current was Br⁻≒ I⁻ > Cl⁻. BORDIC current was not affected by basolaterally applied bumetanide (0.5 mm). Basolateral DIDS (0.2 mm) but not apical DIDS inhibited CFTR mediated short-circuit current (I _sc ) in an intact monolayer of rat airway epithelia, a T84 human colonal epithelial cell line, and a Calu-3 human airway epithelial cell line. This is the first report showing that depolarization induced Cl⁻ current is present on the basolateral membrane of airway epithelia. Received: 7 October 1999/Revised: 24 April 2000     

Regulation of acetylcholine-induced phosphorylation of PLD1 in porcine tracheal smooth muscle

The muscarinic agonist, acetylcholine (ACh), stimulates phospholipase D (PLD) activity in tracheal smooth muscle cells. Direct activation of protein kinase C (PKC) by phorbol-12-myristate-13-acetate (PMA) also stimulates PLD in this tissue. Activation of ACh-induced PLD was inhibited by the tyrosine kinase inhibitor genistein in a concentration-dependent manner. Presently known isoforms of PLD, PLD1 and PLD2, were identified in tracheal smooth muscle and their activation-induced phosphorylation status studied. Both ACh and PMA increased phosphorylation of PLD1 that was significantly blocked by genistein or the PKC inhibitor calphostin C. PLD2 phosphorylation was not detected in the present experiments. Western blots probed with an anti-phosphotyrosine antibody indicate that PLD1 in this tissue is phosphorylated on tyrosine residues after ACh or PMA stimulation. Tyrosine phosphorylation of PLD1 was blocked by genistein and calphostin C. No tyrosine residues were phosphorylated on PLD2. Taken together, these results demonstrate that porcine tracheal smooth muscle cells express both isoforms PLD1 and PLD2. However, on muscarinic activation only PLD1 in this tissue is phosphorylated by PKC via a tyrosine-kinase-dependent pathway.     

基于p38MAPK通路探讨银杏叶提取物对慢性阻塞性肺疾病大鼠气道黏液高分泌及血管重塑的影响

摘要 目的：探讨银杏叶提取物（Ginkgo biloba extract, GBE）通过调控p38MAPK通路对慢性阻塞性肺疾病（chronic obstructive pulmonary disease,COPD）大鼠气道黏液高分泌及肺血管重塑的影响。方法：将90只大鼠随机分为空白对照组、COPD模型组、GBE高剂量组、GBE中剂量组、GBE低剂量组、SB203580组。采用香烟烟雾熏吸联合气道内注入脂多糖（LPS）的方法建立COPD大鼠模型,造模结束后分组给药;通过维多利亚蓝+VG染色观察大鼠肺小动脉病理改变,测量血管壁厚度占血管外径百分比（WT%）、管壁面积占血管面积百分比（WA%）的变化;酶联免疫吸附法（ELISA）检测大鼠肺泡灌洗液（BALF）与血清中TNF-α、TGF-β的表达;实时荧光定量法（RT-PCR）检测肺组织表皮生长因子受体（EGFR）、黏蛋白5AC（MUC5AC）mRNA表达;蛋白质印迹法（Western Blot）检测肺组织EGFR、MUC5AC、p-p38MAPK蛋白的表达。结果：与空白对照组比较,COPD模型组WT%、WA%明显升高（P＜0.05）;与COPD模型组比较,各药物干预组WT%、WA%明显降低（P＜0.05）;COPD模型组大鼠BALF及血清中TNF-α、TGF-β水平较空白对照组明显升高（P＜0.05）,各药物干预组TNF-α、TGF-β水平较COPD模型组明显下降（P＜0.05）;COPD模型组大鼠肺组织EGFR、MUC5AC mRNA与空白对照组相比明显升高（P＜0.05）,各药物干预组大鼠肺组织EGFR、MUC5AC mRNA与COPD模型组相比显著降低（P＜0.05）;COPD模型组大鼠肺组织中EGFR、MUC5AC、p-p38MAPK蛋白的表达与空白对照组相比明显升高（P＜0.05）,各药物干预组大鼠肺组织中EGFR、MUC5AC、p-p38MAPK蛋白的表达与COPD模型组相比明显降低（P＜0.05）,不同GBE剂量干预组中EGFR、MUC5AC、p-p38MAPK蛋白的表达量随着给药剂量增加而减少。结论：GBE能够抑制COPD大鼠气道黏液分泌、改善肺血管重塑,其机制可能与抑制p38MAPK通路有关。     

Acid-induced modulation of airway basal tone and contractility: role of acid-sensing ion channels (ASICs) and TRPV1 receptor

The role of extracellular acidosis in inflammatory airway diseases is not well known. One consequence of tissue acidification is the stimulation of sensory nerves via the polymodal H(+)-gated transmembrane channels ASICs and TRPV1 receptor. The present study investigated the effect of acidosis on airway basal tone and responsiveness in the guinea pig. Acidosis (pH 6.8, 10 min, 37 degrees C) significantly decreased the basal tone of tracheal rings (p<0.01 vs. paired control). Moreover, pH fall raised the maximal contraction of tracheal rings to acetylcholine (p<0.05 vs. paired control). The pH-induced relaxation of airway basal tone was inhibited by pretreatments with ASIC1a or ASIC3/ASIC2a inhibitors (0.5 mM ibuprofen, 0.1 mM gadolinium), nitric oxide synthase inhibitor (1 mM L-NAME), and guanylate cyclase inhibitor (1 microM ODQ). In contrast, the pH-induced relaxation of airway basal tone was not modified by epithelium removal or pretreatments with a TRPV1 antagonist (1 microM capsazepine), a combination of NK(1,2,3) receptor antagonists (0.1 microM each), a blocker of voltage-sensitive Na(+) channels (1 microM tetrodotoxin), a cyclooxygenase inhibitor with no activity on ASICs (1 microM indomethacin) or ASIC3 and ASIC3/ASIC2b inhibitors (10 nM diclofenac, 1 microM aspirin). Furthermore, acid-induced hyperresponsiveness to acetylcholine was inhibited by epithelium removal, capsazepine, NK(1,2,3) receptor antagonists, tetrodotoxin, amiloride, ibuprofen and diclofenac. In summary, the initial pH-induced airway relaxation seems to be independent of sensory nerves, suggesting a regulation of airway basal tone mediated by smooth muscle ASICs. Conversely, the pH-induced hyperresponsiveness involves sensory nerves-dependent ASICs and TRPV1, and an unknown epithelial component in response to acidosis.     

Primary cultures of the dog's tracheal epithelium: Fine structure,fluid, and electrolyte transport

Summary Cells from the dog's tracheal mucosa formed confluent epithelial sheets in culture. Typical tight junctions separated the apical from the basolateral portion of the cell membrane. The apical portion of the cell contained numerous short microvilli and a pronounced glycocalyx. The basolateral portion of the plasma membrane was unspecialized except for extensive gap junctions between cells. Freeze-fracture showed that the cultured cells lacked the basolateral square (orthogonal) arrays of the original tissue, particles previously implicated in ion transport. Formation of domes indicated the presence of active fluid absorption. Domes appeared between days 4 and 8 of culture and persisted for about 1 week. Cell sheets showed a transepithelial resistance of 400 ·cm² and a short-circuit current (I_sc) of 5 A·cm^–2. The effects of transport inhibitors indicated that both active Na absorption and active Cl secretion were present. I_sc was increased by isoproterenol, prostaglandins E₂ and F₂, vasoactive intestinal peptide, dibutyryl cyclic AMP, leukotrienes C₄ and D₄, and bradykinin. These changes were probably due to stimulation of active Cl secretion.