Free Radical Formation In Aids-related Infection (pseudo

铜绿假单胞菌（P. aeruginosa）具有侵袭性和致病性，在宿主防御异常的患者中产生感染，并且是重要的医院病原体。由铜绿假单胞菌引起的肺炎非常严重，并导致坏死性肺炎。这种肺炎常常加重，在免疫功能低下的患者如AIDS患者中引起严重的急性肺损伤。 铜绿假单胞菌的气管内滴注是众所周知的肺炎和急性肺损伤的模型。因此，暴露于铜绿假单胞菌后的肺炎和急性肺损伤被认为是由自由基、促炎细胞因子、花生四烯酸代谢物和源自浸润的嗜中性粒细胞、活化的巨噬细胞、细菌及其产物的蛋白酶引起的。近年来，自由基作为铜绿假单胞菌感染所致急性肺损伤的最终致病分子受到了特别的关注，尽管在体内铜绿假单胞菌引起的肺损伤中没有直接的自由基产生的证据。因此，使用电子自旋共振（ESR）和自旋捕获技术与α-（4-吡啶基-1-氧化物）-N-叔丁基硝酮（POBN），我们研究了在体内自由基的产生与铜绿假单胞菌处理大鼠的气管内滴注。LPS滴注后24小时，通过支气管肺泡灌洗的中性粒细胞浸润的组织学分析证实了炎症反应。来自感染铜绿假单胞菌24小时的肺的脂质提取物的ESR光谱给出了与POBN的碳中心自由基自旋加合物的光谱一致的光谱（aN= 14.86 +/-0.03G和aH-β = 2.48 +/-0.09G）。铜绿假单胞菌感染显著增加ESR谱的强度（相对强度;铜绿假单胞菌感染20.71 +/- 8.67 mm，对照6.50 +/- 1.41 mm，p < 0.01）。以前的研究已经暂时指定这种自由基加合物作为体内脂质过氧化的产物。为了进一步研究铜绿假单胞菌诱导的自由基产生的机制，用吞噬毒性剂GdCl 3预处理大鼠，其显著降低了自由基加合物的产生，相应地减少了中性粒细胞浸润，如组织病理学研究所示。已证实该系统中自由基的产生依赖于吞噬细胞，其可以是活化的巨噬细胞或中性粒细胞。 总之，用铜绿假单胞菌肺内滴注处理的大鼠在肺中产生自由基，如ESR分析所证明的。

Pseudomonas aeruginosa (P. aeruginosa) is invasive and toxigenic, produces infections in patients with abnormal host defenses, and is an important nosocomial pathogen. The pneumonia caused by P. aeruginosa is very severe and results in necrotizing pneumonia. Frequently this pneumonia is exacerbated to cause severe acute lung injury in immunocompromised patients such as AIDS patients. Intratracheal instillation of P. aeruginosa is well known as a model of pneumonia and acute lung injury. Thus, pneumonia and acute lung injury after exposure to P. aeruginosa is thought to be caused by free radicals, proinflammatory cytokines, arachidonic acid metabolites, and proteases derived from infiltrated neutrophils, activated macrophages, bacteria, and their products. Recently, free radicals have been a special focus as the final causative molecules in the pathogenesis of acute lung injury caused by P. aeruginosa infection, although there is no direct evidence of free radical generation in lung injury caused by P. aeruginosa in vivo. Therefore, using electron spin resonance (ESR) and the spin-trapping technique with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN), we investigated in vivo free radical production by rats treated with intratracheal instillation of P. aeruginosa. Twenty-four hours after instillation of LPS, an inflammatory response was confirmed by histological analysis of neutrophil infiltration by broncho-alveolar lavage. ESR spectroscopy of lipid extract from lungs infected with P. aeruginosa for 24 hours gave a spectrum consistent with that of a carbon-centered radical spin adduct of POBN (aN= 14.86 +/- 0.03 G and aH-beta= 2.48 +/- 0.09 G). The intensity of ESR spectra was significantly increased by the infection of P. aeruginosa (Relative intensity; P. aeruginosa infection 20.71 +/- 8.67 mm, Control 6.50 +/- 1.41 mm, p < 0.01). Previous investigations have tentatively assigned this radical adduct as a product of in vivo lipid peroxidation. To further investigate the mechanism of P. aeruginosa-induced free radical generation, rats were pretreated with the phagocytic toxicant GdCl3, which significantly decreased the production of radical adducts with a corresponding decrease in neutrophil infiltration as indicated by histopathological studies. It was confirmed that free radical production in this system depended on phagocytes, which could be either activated macrophages or neutrophils. In conclusion, rats treated with intratracheal instillation of P. aeruginosa generate free radicals in the lung as demonstrated by ESR analysis.