Pseudomonas aeruginosa protease IV degrades surfactant proteins and inhibits surfactant host defense and biophysical functions
Pseudomonas aeruginosa protease IV degrades surfactant proteins and inhibits surfactant host defense and biophysical functions
复制标题
DOI：
10.1152/ajplung.00322.2004
复制
发表时间：
2005-02-01
影响因子：
4.9
通讯作者：
Wright, JR
中科院分区：
文献类型：
--
作者：
Malloy, JL;Veldhuizen, RAW;Wright, JR
肺表面活性剂在肺内具有两种不同的功能：降低气液界面的表面张力和参与先天宿主防御。这两种功能都依赖于表面活性剂相关蛋白。铜绿假单胞菌是囊性纤维化患者呼吸功能障碍和死亡的主要原因，也是医院肺炎的主要病原体。铜绿假单胞菌分泌多种蛋白酶，从而增强其毒力。我们假设铜绿假单胞菌蛋白酶 IV 降解表面活性剂蛋白并导致肺表面活性剂宿主防御和生物物理功能降低。通过凝胶色谱法从铜绿假单胞菌的培养上清液中分离出蛋白酶IV。将无细胞支气管肺泡灌洗液与蛋白酶 IV 一起孵育，导致表面活性蛋白 (SP)-A、-D 和 -B 降解。 SP 被蛋白酶 IV 以时间和剂量依赖性方式降解，并且降解被类胰蛋白酶丝氨酸蛋白酶抑制剂 Nα-对甲苯磺酰基-L-赖氨酸-氯甲基酮 (TLCK) 抑制。蛋白酶 IV 的降解抑制了 SP-A 和 SP-D 介导的细菌聚集和巨噬细胞的摄取。用蛋白酶IV处理的表面活性剂不能像未处理的表面活性剂那样有效地降低表面张力，并且这种效果被TLCK抑制。我们推测，蛋白酶 IV 可能是通过肺内表面活性剂功能丧失而导致与铜绿假单胞菌相关的急性肺损伤发生和传播的重要因素。
Pulmonary surfactant has two distinct functions within the lung: reduction of surface tension at the air-liquid interface and participation in innate host defense. Both functions are dependent on surfactant-associated proteins. Pseudomonas aeruginosa is primarily responsible for respiratory dysfunction and death in cystic fibrosis patients and is also a leading pathogen in nosocomial pneumonia. P. aeruginosa secretes a number of proteases that contribute to its virulence. We hypothesized that P. aeruginosa protease IV degrades surfactant proteins and results in a reduction in pulmonary surfactant host defense and biophysical functions. Protease IV was isolated from cultured supernatant of P. aeruginosa by gel chromatography. Incubation of cell-free bronchoalveolar lavage fluid with protease IV resulted in degradation of surfactant proteins (SP)-A, -D, and -B. SPs were degraded in a time- and dose-dependent fashion by protease IV, and degradation was inhibited by the trypsin-like serine protease inhibitor Nalpha-p-tosyl-L-lysine-chloromethyl ketone ( TLCK). Degradation by protease IV inhibited SP-A- and SP-D-mediated bacterial aggregation and uptake by macrophages. Surfactant treated with protease IV was unable to reduce surface tension as effectively as untreated surfactant, and this effect was inhibited by TLCK. We speculate that protease IV may be an important contributing factor to the development and propagation of acute lung injury associated with P. aeruginosa via loss of surfactant function within the lung.