Role of Rho in the pathophysiology of bronchial asthma

本研究旨在确定Rho参与支气管哮喘的病理生理，如支气管高反应性、β-肾上腺素能脱敏和气道重塑。将载fura-2的气管平滑肌条暴露于1-磷酸鞘氨醇（S1IP,10 μM）超过15分钟后，毒碱受体激动剂甲胆碱（MCh）的收缩作用呈时间依赖性明显增强。然而，MCh对细胞内Ca^<2+>([Ca^<2+>]i)浓度没有影响。在rho激酶选择性抑制剂0.01-1 μM Y-27632的存在下，S1P对MCh（支气管高反应性）的增加反应以浓度依赖性的方式被拮抗。预先暴露于百日咳毒素超过6小时也禁止S1P对MCh的反应增加。然后，在S1P （<1 μM）作用相当时间后，β-肾上腺素能受体激动剂异丙肾上腺素（isoproterenol， ISO）对mch诱导的收缩的抑制作用明显减弱，但[Ca^<2+>]i没有变化。Y-27632以浓度依赖性的方式抑制S1P对ISO （β-肾上腺素能受体的脱敏）的反应性降低。在同等时间内预先暴露于百日咳毒素也禁止S1P对ISO的反应降低。另一方面，在每30分钟重复暴露于ISO后，随着[Ca^<2+>]i的增加，对ISO的反应逐渐减弱。在维拉帕米（一种电压依赖性Ca^<2+>通道的选择性拮抗剂）的存在下，这种对ISO的反应性降低被抑制。在培养的支气管平滑肌细胞中，S1P磷酸化肌球蛋白磷酸酶靶向蛋白（MYPT1），该蛋白是受rho激酶影响的肌球蛋白磷酸酶中的特异性蛋白。Y-27632以浓度依赖性的方式减少支气管平滑肌细胞的增殖（气道重塑）。综上所述，Rho/Rho激酶过程在支气管哮喘的病理生理中起重要作用。少

This study was designed to determine involvement of Rho in the pathophysiology of bronchial asthma such as bronchial hyperreactivity, β-adrenergic desensitization, and airway remodeling. After exposure of the fura-2 loaded strip of tracheal smooth muscle to sphingosine 1-phosphate (S1IP,10 μM) for more than 15 min, contraction by methacholine(MCh), a muscarinic receptor agonist, was markedly augmented in a time-dependent fashion. However, concentration of intracellular Ca^<2+>([Ca^<2+>]i) by MCh was not affected. The increased response to MCh (bronchial hyperreactivity) by S1P was antagonized in the presence of 0.01-1 μM Y-27632, a selective inhibitor of Rho-kinase, in a concentration-dependent fashion. Pre exposure to pertussis toxin over 6 hours also prohibited the increased response to MCh by S1P. Next, after exposure of the tissues to S1P (<1 μM) for an equivalent time, the inhibitory effect of isoproterenol (ISO), a β-adrenergic receptor agonist, against MCh-induced contraction wa … More s markedly attenuated without no change in [Ca^<2+>]i. The reduced responsiveness to ISO (desensitization of β-adrenergic receptors) by S1P was inhibited by Y-27632 in a concentration-dependent fashion. Pre exposure to pertussis toxin over an equivalent time also prohibited the reduced response to ISO by S1P. On the other hand, after repeated exposure to ISO every 30 min, response to ISO was gradually attenuated with an increase in [Ca^<2+>]i. This reduced responsiveness to ISO was inhibited in the presence of verapamil, a selective antagonist of voltage-dependent Ca^<2+> channels. In cultured bronchial smooth muscle cells, S1P phosphorylated myosin phosphatase targeting protein (MYPT1) that is a specific protein in myosin phosphatase affected by Rho-kinase. Proliferation of the bronchial smooth muscle cells (airway remodeling) was reduced by Y-27632 in a concentration-dependent fashion. In conclusion, Rho/Rho-kinase processes play an important role in the pathophysiology of bronchial asthma. Less