Apical trypsin increases ion transport and resistance by a phospholipase C-dependent rise of Ca2+.
Apical trypsin increases ion transport and resistance by a phospholipase C-dependent rise of Ca2+.
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DOI：
10.1152/ajplung.00396.2004
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发表时间：
2005-05
期刊：
影响因子：
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通讯作者：
V. Swystun;Lan Chen;P. Factor;B. Siroky;P. Bell;S. Matalon
中科院分区：
文献类型：
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作者：
V. Swystun;Lan Chen;P. Factor;B. Siroky;P. Bell;S. Matalon
我们研究了丝氨酸蛋白酶改变大鼠肺内液体清除以及气道和肺泡上皮细胞离子载体转运的机制。通过气管内滴注大豆胰酶抑制剂(SBTI)或α(1)-抗胰蛋白酶来抑制内源性蛋白水解酶活性，可降低阿米洛利敏感的肺液通过充满液体的大鼠肺组织的清扫率；注入胰酶可部分恢复这一作用。明胶酶谱显示大鼠肺灌洗液中有SBTI抑制的胰酶样活性。顶端胰酶和人中性粒细胞弹性蛋白酶，但不是蛋白酶激活受体的激动剂，使安装在Ussing小室中的人支气管和鼻腔上皮细胞和大鼠肺泡II型细胞的Na(+)和Cl(-)短路电流(I(Sc))和跨上皮阻力(R(TE))增加至少2小时，这种增加可被阿米洛利和格列本脲完全逆转。哇巴因不能阻止R(TE)的增加，提示胰酶降低了细胞旁电导。顶端胰酶还可引起人呼吸道细胞内钙离子的一过性升高；用BAPTA-AM处理这些细胞可减轻胰酶引起的细胞内钙离子以及I(Sc)和R(Te)的升高。用离子霉素或thapsigargin增加气道细胞内钙离子浓度，可使细胞内钙离子(Sc)升高，而磷脂酶C(PLC)抑制剂可抑制钙离子和i(Sc)的升高。这些数据表明，存在于肺细胞或由炎症细胞释放到肺泡腔的类胰蛋白酶和弹性蛋白酶在肺泡液的清除中发挥着重要作用，它们通过PLC启动的细胞内Ca(2+)升高而增加离子转运和细胞旁阻力。
We investigated the mechanisms by which serine proteases alter lung fluid clearance in rat lungs and vectorial ion transport in airway and alveolar epithelial cells. Inhibition of endogenous protease activity by intratracheal instillation of soybean trypsin inhibitor (SBTI) or alpha(1)-antitrypsin decreased amiloride-sensitive lung fluid clearance across rat fluid-filled lungs; instillation of trypsin partially restored this effect. Gelatin zymography demonstrated SBTI-inhibitable trypsin-like activity in rat lung lavage fluid. Apical trypsin and human neutrophil elastase, but not agonists of protease activated receptors, increased Na(+) and Cl(-) short-circuit currents (I(sc)) and transepithelial resistance (R(TE)) across human bronchial and nasal epithelial cells and rat alveolar type II cells, mounted in Ussing chambers, for at least 2 h. The increase in I(sc) was fully reversed by amiloride and glibenclamide. The increase in R(TE) was not prevented by ouabain, suggesting that trypsin decreased paracellular conductance. Apical trypsin also induced a transient increase in intracellular Ca(2+) in human airway cells; treatment of these cells with BAPTA-AM mitigated the trypsin-induced increases of intracellular Ca(2+) and of I(sc) and R(TE). Increasing intracellular Ca(2+) in airway cells with either ionomycin or thapsigargin reproduced the increase in I(sc), whereas inhibitors of phospholipase C (PLC) prevented the increases in both Ca(2+) and I(sc). These data indicate trypsin-like proteases and elastase, either present in lung cells or released by inflammatory cells into the alveolar space, play an important role in the clearance of alveolar fluid by increasing ion transport and paracellular resistance via a PLC-initiated rise of intracellular Ca(2+).