Chowdhury Kaustav Dutta, Sen Gargi, Sarkar Avik, Biswas Tuli
Indian Institute of Chemical Biology, CSIR, Kolkata-700032, India.
Biochim Biophys Acta. 2011 Jul;1810(7):652-65. doi: 10.1016/j.bbagen.2011.03.019. Epub 2011 Apr 12.
Evidence in the literature suggests that down-regulation of nitric oxide (NO) is associated with the pathophysiological conditions during visceral leishmaniasis (VL). Here we have investigated the mechanism that leads to the down regulation of systemic NO in the infected condition. Moreover, we have determined whether down regulation of NO is associated with increased generation of reactive oxygen species (ROS) during this disease. Therapeutic strategy targeting signaling molecules of these events was evaluated.
Plasma protein-nitrotyrosine was examined by ELISA kit. Generation of superoxides and peroxynitrites was investigated by flow cytometry. NO bioavailability in endothelial cells was evaluated using DAF-2DA fluorescence. Ceramide contents were evaluated using FACS analysis, HPTLC and HPLC.
L. donovani infected reticulo-endothelial cells regulated the activity of eNOS and NAD(P)H oxidase in the endothelial cells through the generation of intercellular messenger, ceramide. Activation of SMases played an important role in the generation of ceramide in animals during chronic infection. These events led to generation of ROS within endothelial cells. Modulation of redox status of plasma and accumulation of ROS in endothelial cells were critically involved in the regulation of NO bioavailability in plasma of the infected animal. Endothelial dysfunction and decline of NO were resulted from an increased production of superoxide where upregulation of eNOS expression appeared as an ineffective compensatory event. Inhibition of ceramide generation increased NO bioavailability, prevented endothelial dysfunction and concomitant oxidative stress.
Decreased NO bioavailability and endothelial dysfunction were the downstream of ceramide signaling cascade. ROS accumulation promoted peroxynitrite generation and reduced NO bioavailability. Inhibition of ceramide generation may be a potential therapeutic option in preventing the co-morbidity associated with VL.
文献证据表明，一氧化氮（NO）下调与内脏利什曼病（VL）期间的病理生理状况相关。在此，我们研究了导致感染状态下全身NO下调的机制。此外，我们还确定了在这种疾病中NO下调是否与活性氧（ROS）生成增加有关。评估了针对这些事件信号分子的治疗策略。
采用ELISA试剂盒检测血浆蛋白硝基酪氨酸。通过流式细胞术研究超氧化物和过氧亚硝酸盐的生成。使用DAF-2DA荧光评估内皮细胞中的NO生物利用度。使用FACS分析、HPTLC和HPLC评估神经酰胺含量。
杜氏利什曼原虫感染的网状内皮细胞通过细胞间信使神经酰胺的生成来调节内皮细胞中eNOS和NAD(P)H氧化酶的活性。在慢性感染期间，SMases的激活在动物体内神经酰胺的生成中起重要作用。这些事件导致内皮细胞内ROS的生成。血浆氧化还原状态的调节和ROS在内皮细胞中的积累严重参与了感染动物血浆中NO生物利用度的调节。内皮功能障碍和NO的下降是由于超氧化物生成增加所致，而eNOS表达上调似乎是一种无效的代偿事件。抑制神经酰胺生成可增加NO生物利用度，预防内皮功能障碍和伴随的氧化应激。
NO生物利用度降低和内皮功能障碍是神经酰胺信号级联反应的下游效应。ROS积累促进过氧亚硝酸盐生成并降低NO生物利用度。抑制神经酰胺生成可能是预防与VL相关合并症的潜在治疗选择。
