ROLE OF APOPTOSIS IN GASTRIC MUCOSAL ATROPHY INDUCED BY HELICOBACTER PYLORI INFECTION

幽门螺杆菌(H.Pylori)感染诱导慢性萎缩性胃炎患者细胞凋亡已有报道。许多研究人员已报道，活性氧和氮类物质，特别是H_2O_2、HClO、NH_2Cl和NO参与了胃粘膜损伤的发病过程。然而，目前尚不清楚这些物种是否影响胃上皮细胞的生长，也不清楚这些物种在增殖和凋亡方面的作用模式可能是什么。在本项目中，使用正常大鼠胃粘膜细胞系RGM-1在体外评价了这些活性物质对粘膜细胞生长和细胞周期的影响。H_2O_2、HClO、NH_2Cl和NO对RGM-1细胞的生长在0.1-100微米范围内呈剂量依赖性抑制作用。NH_2Cl和NO可引起时间和剂量依赖性的G1期细胞丧失和G2/M期细胞积聚，并产生部分亚二倍体细胞，其DNA降解以凋亡为特征。用Hoechst 33342和碘化丙啶进行荧光显微镜观察，证实NH_2Cl-和NO诱导的细胞凋亡。NO处理还引起1)谷胱甘肽含量下降，2)细胞内活性氧产生增加，3)8-OH-脱氧鸟苷的形成。提示NH_2Cl和NO抑制胃粘膜细胞生长，并诱导RGM-1细胞凋亡，这可能是H.作为对这些氧化的胃粘膜细胞具有抑制作用的候选化合物，我们评估了一种新型的水溶性维生素E类似物和天然功能食品的效果。

Induction of apoptosis by Helicobacter pylori (H.pylori) infection has been reported in patients with chronic atrophic gastritis. Many investigators have reported that reactive oxygen and nitrogen species, especially H_2O_2, HClO, NH_2Cl, and NO are involved in the pathogenesis of gastric mucosal injuries. However, it is unclear whether these species affect the growth of gastric epithelial cells, or what the mode of action might be for any such changes in proliferation and apoptosis. In this project, the effects of these reactive species on mucosal cell growth and the cell cycle were evaluated in vitro using a normal rat gastric mucosal cell line RGM-1. H_2O_2, HClO, NH_2Cl, and NO exerted a dose-dependent inhibition of RGM-1 cell growth at 0.1 - 100 muM.Exposure of cells to NH_2Cl and NO caused a time- and dose- dependent loss of G1-phase cells with accumulation of G2/M phase cells, and produced a fraction of subdiploid cells with oligonucleosomal DNA degradation characteristic of apoptosis. NH_2Cl- and NO-induced apoptosis was confirmed by fluorescent microscopy with Hoechst 33342 and propidium iodide. NO treatment also induced 1) the decrease in glutathione content, 2) the increase in inrtracellular reactive oxygen production, and 3) the formation of 8-OH- deoxyguanosine. These results suggest that NH_2Cl and NO inhibits gastric mucosal cell growth, and induces apoptosis in RGM-1 cells, events which may be important in gastric mucosal damage or atrophy induced by H.pylori infection. As a candidate possessing inhibitory properties against these oxidative gastric mucosal cell, we evaluated the effects of a novel water-soluble vitamin E analogue and natural functional foods.