Keates S, Keates A C, Warny M, Peek R M, Murray P G, Kelly C P
Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
J Immunol. 1999 Nov 15;163(10):5552-9.
The aim of this study was to determine whether Helicobacter pylori activates mitogen-activated protein (MAP) kinases in gastric epithelial cells. Infection of AGS cells with an H. pylori cag+ strain rapidly (5 min) induced a dose-dependent activation of extracellular signal-regulated kinases (ERK), p38, and c-Jun N-terminal kinase (JNK) MAP kinases, as determined by Western blot analysis and in vitro kinase assay. Compared with cag+ strains, cag- clinical isolates were less potent in inducing MAP kinase, particularly JNK and p38, activation. Isogenic inactivation of the picB region of the cag pathogenicity island resulted in a similar loss of JNK and p38 MAP kinase activation. The specific MAP kinase inhibitors, PD98059 (25 microM; MAP kinase kinase (MEK-1) inhibitor) and SB203580 (10 microM; p38 inhibitor), reduced H. pylori-induced IL-8 production in AGS cells by 78 and 82%, respectively (p < 0.01 for each). Both inhibitors together completely blocked IL-8 production (p < 0.001). However, the MAP kinase inhibitors did not prevent H. pylori-induced IkappaBalpha degradation or NF-kappaB activation. Thus, H. pylori rapidly activates ERK, p38, and JNK MAP kinases in gastric epithelial cells; cag+ isolates are more potent than cag- strains in inducing MAP kinase phosphorylation and gene products of the cag pathogenicity island are required for maximal MAP kinase activation. p38 and MEK-1 activity are required for H. pylori-induced IL-8 production, but do not appear to be essential for H. pylori-induced NF-kappaB activation. Since MAP kinases regulate cell proliferation, differentiation, programmed death, stress, and inflammatory responses, activation of gastric epithelial cell MAP kinases by H. pylori cag+ strains may be instrumental in inducing gastroduodenal inflammation, ulceration, and neoplasia.
本研究的目的是确定幽门螺杆菌是否激活胃上皮细胞中的丝裂原活化蛋白（MAP）激酶。用幽门螺杆菌cag+菌株感染AGS细胞可迅速（5分钟）诱导细胞外信号调节激酶（ERK）、p38和c-Jun氨基末端激酶（JNK）MAP激酶呈剂量依赖性激活，这是通过蛋白质印迹分析和体外激酶测定确定的。与cag+菌株相比，cag-临床分离株诱导MAP激酶激活的能力较弱，尤其是JNK和p38。cag致病岛picB区域的同基因失活导致JNK和p38 MAP激酶激活能力类似丧失。特异性MAP激酶抑制剂PD98059（25μM；MAP激酶激酶（MEK-1）抑制剂）和SB203580（10μM；p38抑制剂）分别使幽门螺杆菌诱导的AGS细胞中IL-8产生减少78%和82%（每组p<0.01）。两种抑制剂共同作用完全阻断IL-8产生（p<0.001）。然而，MAP激酶抑制剂并不能阻止幽门螺杆菌诱导的IkappaBalpha降解或NF-kappaB激活。因此，幽门螺杆菌可迅速激活胃上皮细胞中的ERK、p38和JNK MAP激酶；cag+分离株在诱导MAP激酶磷酸化方面比cag-菌株更有效，并且cag致病岛的基因产物是最大程度MAP激酶激活所必需的。p38和MEK-1活性是幽门螺杆菌诱导IL-8产生所必需的，但似乎不是幽门螺杆菌诱导NF-kappaB激活所必需的。由于MAP激酶调节细胞增殖、分化、程序性死亡、应激和炎症反应，幽门螺杆菌cag+菌株激活胃上皮细胞MAP激酶可能有助于诱导胃十二指肠炎症、溃疡和肿瘤形成。
