Suppressed apoptosis in the inflamed gastric mucosa of Helicobacter pylori-colonized iNOS-knockout mice.
Suppressed apoptosis in the inflamed gastric mucosa of Helicobacter pylori-colonized iNOS-knockout mice.
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DOI：
10.1016/s0891-5849(03)00218-1
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发表时间：
2003-06
影响因子：
7.4
通讯作者：
M. Miyazawa;Hidekazu Suzuki;T. Masaoka;A. Kai;M. Suematsu;H. Nagata;S. Miura;H. Ishii
中科院分区：
文献类型：
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作者：
M. Miyazawa;Hidekazu Suzuki;T. Masaoka;A. Kai;M. Suematsu;H. Nagata;S. Miura;H. Ishii
幽门螺杆菌 (H. pylori) 定植的胃粘膜细胞更新失调被认为与胃癌发生途径有关。我们之前报道过，与小鼠相比，幽门螺杆菌定植的蒙古沙鼠胃粘膜细胞凋亡减弱，细胞增殖增强，这可能反映了幽门螺杆菌定植与蒙古沙鼠致癌之间的特定联系。两种菌株之间的差异可能归因于宿主遗传背景的差异。诱导型一氧化氮合酶（iNOS）被认为不仅参与炎症反应，而且还参与幽门螺杆菌定植的胃粘膜中胃粘膜细胞更新的调节。因此，本研究旨在检测 iNOS 敲除小鼠接种幽门螺杆菌后胃白细胞活化和胃粘膜上皮细胞凋亡。方法：iNOS 基因敲除小鼠 (iNOS−/−) 及其 iNOS+/+ 同窝小鼠口服接种幽门螺杆菌悉尼菌株（SS1，108 个菌落形成单位 [CFU]）。通过微需氧细菌培养证实幽门螺杆菌感染。接种后14周和30周对每只小鼠的胃进行评估。根据更新的 Sydney 系统，通过测定髓过氧化物酶 (MPO) 活性和组织学评分来评估多形核白细胞 (PMN) 的胃粘膜积聚。通过估计单核小体和寡核小体的细胞质水平以及通过末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记方法来测定细胞凋亡水平。结果：接种 SS1 的小鼠表现出幽门螺杆菌持续定植 12 周。虽然在 iNOS+/+ 和 iNOS−/− 菌株中接种 SS1 后胃粘膜 PMN 浸润增加，但仅在 SS1 定植的 iNOS+/+ 小鼠中观察到 DNA 碎片增强，而在 iNOS−/− 小鼠中未观察到。总之，尽管即使在 iNOS−/− 小鼠的胃粘膜中也能引起对幽门螺杆菌反应的 PMN 募集，但幽门螺杆菌诱导的上皮细胞凋亡在该菌株中减弱。这些数据表明，iNOS可能在促进幽门螺杆菌感染的发炎胃粘膜细胞凋亡中发挥重要作用，并且幽门螺杆菌感染的iNOS−/−小鼠中持续的炎症而不凋亡可能与肿瘤前转化有关。
Deregulated cell turnover in Helicobacter pylori (H. pylori)-colonized gastric mucosa has been suggested to be linked to the gastric carcinogenesis pathway. We previously reported attenuation of apoptosis and enhancement of cellular proliferation in the H. pylori-colonized gastric mucosa of Mongolian gerbils as compared to that in mice, which might reflect a specific link between H. pylori colonization and carcinogenesis in the Mongolian gerbils; the difference between the two strains could be attributable to differences in the host genetic background. Inducible-type nitric oxide synthase (iNOS) is thought to participate in not only the inflammatory response, but also in the regulation of gastric mucosal cell turnover in H. pylori-colonized gastric mucosa. Thus, the present study was designed to examine gastric leukocyte activation and epithelial cell apoptosis in the gastric mucosa following H. pylori inoculation in iNOS-knockout mice. Methods: iNOS-knockout mice (iNOS−/−) and their iNOS+/+littermates were orally inoculated with the Sydney strain of H. pylori (SS1, 108colony-forming units [CFU]). H. pylori infection was confirmed by microaerobic bacterial culture. The stomach of each mouse was evaluated 14 weeks and 30 weeks after the inoculation. Gastric mucosal accumulation of polymorphonuclear leukocytes (PMN) was assessed by determining the myeloperoxidase (MPO) activity and histological score based on the updated Sydney system. The level of apoptosis was determined by estimation of the cytoplasmic levels of mono- and oligonucleosomes and by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method. Results: The SS1-inoculated mice showed persistent H. pylori colonization for 12 weeks. While gastric mucosal PMN infiltration increased following SS1 inoculation in both iNOS+/+and iNOS−/−strains, enhanced DNA fragmentation was observed in only SS1-colonized iNOS+/+mice, and not in the iNOS−/−mice. In conclusion, although the recruitment of PMN in response to H. pylori was evoked even in the gastric mucosa of iNOS−/−mice, epithelial cell apoptosis induced by H. pylori was attenuated in this strain. These data suggest that iNOS may play an important role in promoting apoptosis in the H. pylori-infected inflamed gastric mucosa, and that persistent inflammation without apoptosis in iNOS−/−mice with H. pylori infection may be linked to preneoplastic transformation.