The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has b...The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has been reported to alter overall cellular metabolism, there is little known about the consequences of extended exposure to the toxin. Here, we describe studies to address this gap in knowledge, which have revealed that mitochondrial dysfunction and fragmentation are followed by a time-dependent recovery of mitochondrial structure, mitochondrial transmembrane potential, and cellular ATP levels. Cells exposed to VacA also initially demonstrated a reduction in oxidative phosphorylation, as well as increase in compensatory aerobic glycolysis. These metabolic alterations were reversed in cells with limited toxin exposure, congruent with the recovery of mitochondrial transmembrane potential and the absence of cytochrome c release from the mitochondria. Taken together, these results are consistent with a model that mitochondrial structure and function are restored in VacA-intoxicated cells.展开更多
目的:观察黄芪含药血清能否有效抑制体外幽门螺杆菌(hel i cobact er pyl ori,Hp)空泡毒素(VacA)的活性,从而探讨其抗菌机制。方法:将HP菌株培养上清液制成粗制VacA蛋白,经倍比稀释后(1∶32～1∶1),选择1∶2滴度与不同浓度黄芪含药血清...目的:观察黄芪含药血清能否有效抑制体外幽门螺杆菌(hel i cobact er pyl ori,Hp)空泡毒素(VacA)的活性,从而探讨其抗菌机制。方法:将HP菌株培养上清液制成粗制VacA蛋白,经倍比稀释后(1∶32～1∶1),选择1∶2滴度与不同浓度黄芪含药血清共同作用于胃癌SGC-7901细胞,观察胃癌细胞形态变化,采用中性红摄入法(NRU)评价空泡活性。结果:黄芪含药血清对VacA活性有显著抑制作用,含药血清小剂量组NRU检测其空泡活性A550=0.228±0.029,显微镜下计数空泡形成率为78.75%±8.539%,与阴性对照组比较差异有显著性(P<0.05),随血清含药浓度的增加A550和空泡形成率逐渐降低;含药血清大剂量组A550=0.127±0.047,空泡形成率为32.25%±10.21%,与阴性对照组比较差异有极显著性(P<0.01),与阳性对照奥美拉唑组比较差异无显著性(P>0.05);含药血清大剂量组与中剂量组A550比较,差异无显著性(P>0.05),与小剂量组比较差异有显著性(P<0.05),可见黄芪含药血清对空泡毒素的抑制作用具有浓度依赖性。结论:黄芪对HP VacA活性具有明显的抑制作用,且该抑制作用具有一定的浓度依赖性。展开更多
文摘The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has been reported to alter overall cellular metabolism, there is little known about the consequences of extended exposure to the toxin. Here, we describe studies to address this gap in knowledge, which have revealed that mitochondrial dysfunction and fragmentation are followed by a time-dependent recovery of mitochondrial structure, mitochondrial transmembrane potential, and cellular ATP levels. Cells exposed to VacA also initially demonstrated a reduction in oxidative phosphorylation, as well as increase in compensatory aerobic glycolysis. These metabolic alterations were reversed in cells with limited toxin exposure, congruent with the recovery of mitochondrial transmembrane potential and the absence of cytochrome c release from the mitochondria. Taken together, these results are consistent with a model that mitochondrial structure and function are restored in VacA-intoxicated cells.
文摘目的:观察黄芪含药血清能否有效抑制体外幽门螺杆菌(hel i cobact er pyl ori,Hp)空泡毒素(VacA)的活性,从而探讨其抗菌机制。方法:将HP菌株培养上清液制成粗制VacA蛋白,经倍比稀释后(1∶32～1∶1),选择1∶2滴度与不同浓度黄芪含药血清共同作用于胃癌SGC-7901细胞,观察胃癌细胞形态变化,采用中性红摄入法(NRU)评价空泡活性。结果:黄芪含药血清对VacA活性有显著抑制作用,含药血清小剂量组NRU检测其空泡活性A550=0.228±0.029,显微镜下计数空泡形成率为78.75%±8.539%,与阴性对照组比较差异有显著性(P<0.05),随血清含药浓度的增加A550和空泡形成率逐渐降低;含药血清大剂量组A550=0.127±0.047,空泡形成率为32.25%±10.21%,与阴性对照组比较差异有极显著性(P<0.01),与阳性对照奥美拉唑组比较差异无显著性(P>0.05);含药血清大剂量组与中剂量组A550比较,差异无显著性(P>0.05),与小剂量组比较差异有显著性(P<0.05),可见黄芪含药血清对空泡毒素的抑制作用具有浓度依赖性。结论:黄芪对HP VacA活性具有明显的抑制作用,且该抑制作用具有一定的浓度依赖性。
