Department of Surgery, School of Medicine, University of Western Sydney, Building 30, Goldsmith Avenue, Campbelltown, NSW 2560, Australia.
Department of Surgery, School of Medicine, University of Western Sydney, Building 30, Goldsmith Avenue, Campbelltown, NSW 2560, Australia.
Chem Biol Interact. 2015 May 5;232:30-7. doi: 10.1016/j.cbi.2015.03.011. Epub 2015 Mar 17.
Pseudomonas aeruginosa is an important human pathogen associated with several acute and chronic conditions, including diseases of the airways and wounds. The organism produces pyocyanin, an extracellular redox toxin that induces oxidative stress, depletes intracellular glutathione (GSH) and induces proliferative arrest and apoptosis, thus compromising the ability of tissue to repair itself. GSH is an important intra- and extracellular antioxidant, redox buffer and detoxifies xenobiotics by increasing their polarity, which facilitates their elimination. As previous studies have reported exogenous GSH to be protective against pyocyanin toxicity, this study was undertaken to explore the mechanism by which GSH protects host cells from the deleterious effects of the toxin. Co-incubation of pyocyanin with GSH resulted in a time-dependent diminished recovery of the toxin from the incubation medium. Concurrently, a highly polar green-colored metabolite was recovered that exhibited a UV-visible spectrum similar to pyocyanin and which was determined by mass spectrometry to have a major ion (m/z = 516) consistent with a glutathione conjugate. The ability of the conjugate to oxidize NADPH and to reduce molecular oxygen with the production of reactive oxygen species was comparable to pyocyanin yet it no longer demonstrated cytotoxicity towards host cells. These data suggest that GSH forms a cell-impermeant conjugate with pyocyanin and that availability of the thiol may be critical to minimizing the toxicity of this important bacterial virulence factor at infection sites. Our data indicate that for GSH to have a clinically effective role in neutralizing pyocyanin, the thiol needs to be available at millimolar concentrations.
铜绿假单胞菌是一种重要的人类病原体，与多种急性和慢性疾病有关，包括呼吸道疾病和伤口感染。该细菌产生绿脓菌素，这是一种细胞外氧化还原毒素，可诱导氧化应激，耗尽细胞内谷胱甘肽（GSH）并诱导增殖停滞和细胞凋亡，从而损害组织自我修复的能力。GSH 是一种重要的细胞内和细胞外抗氧化剂、氧化还原缓冲剂，通过增加其极性使外源性物质解毒，从而促进其消除。由于先前的研究报告称外源性 GSH 可抵抗绿脓菌素毒性，因此本研究旨在探讨 GSH 保护宿主细胞免受毒素有害影响的机制。绿脓菌素与 GSH 共同孵育会导致毒素从孵育培养基中的恢复时间呈时间依赖性下降。同时，回收了一种高极性的绿色代谢产物，其紫外可见光谱与绿脓菌素相似，通过质谱法确定其主要离子（m/z = 516）与谷胱甘肽缀合物一致。该缀合物氧化 NADPH 和还原分子氧并产生活性氧的能力与绿脓菌素相当，但对宿主细胞不再表现出细胞毒性。这些数据表明，GSH 与绿脓菌素形成一种细胞不可渗透的缀合物，而巯基的可用性对于减少感染部位这种重要细菌毒力因子的毒性可能至关重要。我们的数据表明，为了使 GSH 在中和绿脓菌素方面具有临床效果，硫醇需要以毫摩尔浓度存在。
