The Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
J Gastroenterol. 2011 Oct;46(10):1167-76. doi: 10.1007/s00535-011-0434-6. Epub 2011 Jul 26.
Gastric hydrochloric acid (HCl) has been regarded as an inciting factor in gastric mucosal injuries and has been reported to induce lipid peroxidation in vitro. However, because HCl is not an oxidant per se, the exact mechanism by which the acid induces lipid peroxidation is unknown. We hypothesized that gastric acid may disrupt mitochondrial transmembrane potential and induce the production of superoxide in mitochondria, which subsequently may induce lipid peroxidation and apoptosis in gastric mucosal cells.
Firstly we treated gastric epithelial RGM1 cells with solutions containing various concentrations of HCl (i.e., of varying pH), and examined cellular injury, lipid peroxidation, and apoptosis with specific fluorescent dyes. Secondly, we performed electron paramagnetic resonance (EPR) spectroscopy of isolated, acid-exposed mitochondria from the cells, using a spin-trapping reagent for superoxide, 5-(2,2-dimethyl-1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO). Finally, we established novel RGM1 cells that overexpressed manganese superoxide dismutase (MnSOD), which removes superoxide from mitochondria, and examined the effect of acid treatment on cellular membrane lipid peroxidation.
The results indicated that the exposure to acid indeed induced cellular injury, cellular lipid peroxidation, apoptosis, and the demonstration of the exact superoxide spectra on EPR spectroscopy in gastric epithelial cells, and that overexpression of MnSOD decreased superoxide production and prevented cellular lipid peroxidation.
These results suggested that gastric acid, like nonsteroidal anti-inflammatory drugs (NSAIDs), induces mitochondrial superoxide production, which induces gastric cellular injury by triggering cellular lipid peroxidation and apoptosis.
胃盐酸（HCl）一直被认为是胃黏膜损伤的激发因素，并已被报道在体外诱导脂质过氧化。然而，由于 HCl 本身不是氧化剂，酸诱导脂质过氧化的确切机制尚不清楚。我们假设胃酸可能破坏线粒体跨膜电位，并诱导线粒体中超氧的产生，这可能随后诱导胃黏膜细胞的脂质过氧化和凋亡。
首先，我们用含有不同浓度 HCl（即不同 pH 值）的溶液处理胃上皮细胞 RGM1，并使用特定的荧光染料检测细胞损伤、脂质过氧化和凋亡。其次，我们对来自细胞的暴露于酸的分离线粒体进行电子顺磁共振（EPR）光谱学分析，使用超氧的自旋捕获试剂 5-(2,2-二甲基-1,3-丙氧基膦酰基)-5-甲基-1-吡咯啉 N-氧化物（CYPMPO）。最后，我们建立了过表达锰超氧化物歧化酶（MnSOD）的新型 RGM1 细胞，MnSOD 可从线粒体中清除超氧，我们检测了酸处理对细胞膜脂质过氧化的影响。
结果表明，暴露于酸确实诱导了胃上皮细胞的细胞损伤、细胞脂质过氧化、凋亡，并在 EPR 光谱学上证明了确切的超氧谱，而过表达 MnSOD 可减少超氧的产生并防止细胞脂质过氧化。
这些结果表明，胃酸与非甾体抗炎药（NSAIDs）一样，诱导线粒体中超氧的产生，通过触发细胞脂质过氧化和凋亡来诱导胃细胞损伤。
