AQP5细胞信号网络在幽门螺杆菌感染早期致病中的作用

The pathogenic mechanism of Helicobacter pylori (Hp) infection is still undefined. We confirmed that disruption of proliferation and apoptosis and epithelial-mesenchymal transition (EMT) of gastric epithelial cells was induced by Hp infection, and E-cadherin was significantly less expressed in chronic non-atrophic gastritis infected with Hp than those without Hp infection, these results indicated that Hp infection was closely associated with early pathopoiesis of gastric mucosa diseases. Our previous study indicated that AQP5 was over-expressed in multiple gastric cancer cells and intestinal metaplasia tissuse, and promoted proliferation and migration; AQP5 protein was significantly over-expressed in gastric mucosa of Mongolian gerbils infected with Hp. Based on these results and other previous studies that AQP5 was up-regulated by cAMP/PKA signaling pathway, followed by activation of the Ras-MAPK signaling pathway which was involved in EMT, it is reasonable to speculate a novel pathogenic mechanism: disruption of proliferation and apoptosis and EMT of gastric epithelial cells is caused by Hp infection through inducing aberrant expression of cAMP/PKA/AQP5/Ras-MAPK signaling network, which is involved in early pathopoiesis of gastric mucosa diseases. This study is expected to elucidate the effect of AQP5 signaling network in early pathopoiesis of Hp infection and associated mechanisms by human gastric mucosa samples, AQP5 knockout mice infected with Hp and cell experiment, and provide new insights into the exploration of new molecular targets for gene therapy clinically.

Hp感染致病机制不明。我们发现Hp感染诱导胃粘膜上皮细胞增殖、凋亡失衡及上皮-间质转化（EMT），且Hp感染的慢性非萎缩性胃炎E-钙粘蛋白水平显著低于未感染组，提示Hp感染与胃粘膜疾病的早期发病相关。前期研究表明AQP5在胃癌细胞系及肠化组织中均为高表达，促进胃癌细胞系增殖及迁移；Hp感染诱导蒙古沙鼠胃粘膜AQP5蛋白表达。结合既往研究所示cAMP/PKA调节AQP5，并可通过下游的Ras-MAPK信号通路调控EMT，我们推测Hp感染新的致病机制：Hp感染促发cAMP/PKA/AQP5/Ras-MAPK信号网络异常，诱导胃粘膜上皮细胞增殖、凋亡失衡及EMT，参与胃粘膜疾病的早期致病。本研究拟通过人胃粘膜标本、Hp感染AQP5基因敲除小鼠及细胞实验，阐明AQP5信号网络在Hp感染早期致病中的作用及具体机制，为临床探索基因治疗的分子靶点提供依据。

Hp感染与多种消化系疾病的发生密切相关，但是其致病机制仍不清楚。我们发现Hp感染诱导胃黏膜上皮细胞增殖凋亡失衡及上皮间充质转化（EMT），Hp感染诱导AQP5表达上调。本项目深入研究AQP5在Hp感染诱导EMT中的分子机制。.首先，收集人体胃黏膜不同病变阶段包括胃炎、肠上皮化生、异型增生和胃癌的组织，检测AQP5、EMT相关指标E-cadherin、N-cadherin的表达；其次，通过体外实验验证Hp感染胃上皮细胞对EMT的影响，AQP5在Hp感染诱导EMT中的作用以及敲减AQP5后对Hp感染致生物行为学的影响；最后，探讨AQP5促进Hp感染诱导EMT的分子机制。.我们发现随着胃黏膜病变加重AQP5的表达水平逐渐上调，EMT相关指标E-cadherin表达降低，N-cadherin表达逐渐上调。Hp感染胃炎患者中AQP5表达明显高于Hp未感染组。Hp感染胃炎患者E-cadherin水平显著低于Hp未感染者，间充质标志物 N-cadherin呈相反的趋势。Hp感染胃上皮细胞后AQP5以MOI依赖、时间依赖的方式逐渐增加。Hp PMSS1感染转基因INS-GAS小鼠4个月后AQP5表达显著升高。胃上皮细胞敲减AQP5后可显著抑制Hp感染诱导的细胞增殖、侵袭，促进细胞凋亡。进一步，AQP5敲减可显著抑制Hp感染诱导的EMT转录因子表达。Hp感染显著上调E-cadherin、下调 N-cadherin水平，而敲除AQP5逆转了这种作用。最后，我们发现AQP5过表达后显著增加ERK1/2和MEK磷酸化、及下游蛋白Myc；敲除AQP5后抑制了Hp感染对MEK/ERK信号通路的激活。.我们的研究表明Hp感染可激活AQP5表达，进而通过促进MEK/ERK通路诱导EMT发生，引起胃上皮细胞恶性转化。研究结果为Hp的根除及Hp感染相关疾病的防治提供了重要的理论依据。