Anathy Vikas, Aesif Scott W, Hoffman Sidra M, Bement Jenna L, Guala Amy S, Lahue Karolyn G, Leclair Laurie W, Suratt Benjamin T, Cool Carlyne D, Wargo Matthew J, Janssen-Heininger Yvonne M W
1 Department of Pathology.
Am J Respir Crit Care Med. 2014 Feb 15;189(4):463-74. doi: 10.1164/rccm.201310-1905OC.
The death receptor Fas is critical for bacterial clearance and survival of mice after Pseudomonas aeruginosa infection.
Fas ligand (FasL)-induced apoptosis is augmented by S-glutathionylation of Fas (Fas-SSG), which can be reversed by glutaredoxin-1 (Grx1). Therefore, the objective of this study was to investigate the interplay between Grx1 and Fas in regulating the clearance of P. aeruginosa infection.
Lung samples from patients with bronchopneumonia were analyzed by immunofluorescence. Primary tracheal epithelial cells, mice lacking the gene for Grx1 (Glrx1(-/-)), Glrx1(-/-) mice treated with caspase inhibitor, or transgenic mice overexpressing Grx1 in the airway epithelium were analyzed after infection with P. aeruginosa.
Patient lung samples positive for P. aeruginosa infection demonstrated increased Fas-SSG compared with normal lung samples. Compared with wild-type primary lung epithelial cells, infection of Glrx1(-/-) cells with P. aeruginosa showed enhanced caspase 8 and 3 activities and cell death in association with increases in Fas-SSG. Infection of Glrx1(-/-) mice with P. aeruginosa resulted in enhanced caspase activity and increased Fas-SSG as compared with wild-type littermates. Absence of Glrx1 significantly enhanced bacterial clearance, and decreased mortality postinfection with P. aeruginosa. Inhibition of caspases significantly decreased bacterial clearance postinfection with P. aeruginosa, in association with decreased Fas-SSG. In contrast, transgenic mice that overexpress Grx1 in lung epithelial cells had significantly higher lung bacterial loads, enhanced mortality, decreased caspase activation, and Fas-SSG in the lung after infection with P. aeruginosa, compared with wild-type control animals.
These results suggest that S-glutathionylation of Fas within the lung epithelium enhances epithelial apoptosis and promotes clearance of P. aeruginosa and that glutaredoxin-1 impairs bacterial clearance and increases the severity of pneumonia in association with deglutathionylation of Fas.
死亡受体Fas对铜绿假单胞菌感染后小鼠的细菌清除和存活至关重要。
Fas配体（FasL）诱导的细胞凋亡通过Fas的S-谷胱甘肽化（Fas-SSG）增强，而谷氧还蛋白-1（Grx1）可使其逆转。因此，本研究的目的是探讨Grx1与Fas在调节铜绿假单胞菌感染清除中的相互作用。
通过免疫荧光分析支气管肺炎患者的肺组织样本。用铜绿假单胞菌感染后，对原代气管上皮细胞、缺乏Grx1基因的小鼠（Glrx1(-/-)）、用半胱天冬酶抑制剂处理的Glrx1(-/-)小鼠或气道上皮中过表达Grx1的转基因小鼠进行分析。
与正常肺组织样本相比，铜绿假单胞菌感染阳性的患者肺组织样本显示Fas-SSG增加。与野生型原代肺上皮细胞相比，用铜绿假单胞菌感染Glrx1(-/-)细胞显示半胱天冬酶8和3活性增强以及细胞死亡增加，同时Fas-SSG增加。与野生型同窝小鼠相比，用铜绿假单胞菌感染Glrx1(-/-)小鼠导致半胱天冬酶活性增强和Fas-SSG增加。缺乏Grx1显著增强了细菌清除，并降低了铜绿假单胞菌感染后的死亡率。抑制半胱天冬酶显著降低了铜绿假单胞菌感染后的细菌清除，同时Fas-SSG减少。相反，与野生型对照动物相比，在肺上皮细胞中过表达Grx1的转基因小鼠在感染铜绿假单胞菌后肺细菌载量显著更高、死亡率增加、半胱天冬酶激活减少以及肺中Fas-SSG减少。
这些结果表明，肺上皮细胞内Fas的S-谷胱甘肽化增强上皮细胞凋亡并促进铜绿假单胞菌的清除，而谷氧还蛋白-1与Fas的去谷胱甘肽化相关，损害细菌清除并增加肺炎的严重程度。
