Physiological action of nitric oxide produced by a stimulation of endotoxin from Helicobacter pylori on gastric mucosa

幽门螺杆菌是一种革兰氏阴性菌，是胃炎的主要原因，也是消化性溃疡的主要原因。一氧化氮（NO）是由脂多糖或革兰氏阴性菌的内毒素诱导一氧化氮合酶（iNOS）的Ca^<2+>独立异构体释放的，已知对胃粘膜有害。为了阐明幽门螺杆菌LPS对胃粘膜的生理作用和NO的作用，本研究以大肠杆菌LPS为对照，进行了体内和体外实验研究。采用苯酚-水萃取法从革兰氏菌中分离得到幽门螺杆菌LPS，并通过酶切法对RNA、DNA和蛋白质进行酶切纯化。研究了内毒素血症大鼠胃粘膜iNOS产物与环氧化酶（COX）的体外串扰。结果表明，在玉米螟多糖处理的大鼠胃粘膜中，COX产物PGE2在iNOS激活后增强。COX活性对iNOS-NO通路的影响在胃粘膜完整性炎症状态的调节中具有重要意义。我们利用正常小鼠胃表面黏液细胞系（GSM06）进一步阐明了LPS与胃上皮细胞的相互作用。我们的研究结果表明，来自幽门螺杆菌和大肠杆菌的lps均通过在GSM06中组成性表达的TLR 4诱导iNOS和toll样受体（TLR） 2。tlr2诱导的这一机制对于维持胃粘膜完整性至关重要。

Helicobacter pylori, a gram-negative bacterium, is the primary cause of gastritis and a major contributor to peptic ulcer disease. Despite its importance as a human pathogen, principal factor of pathogenicity of the bacterium remains to be identified Nitric oxide (NO) released due to the induction of Ca^<2+> independent isoform of nitric oxide synthase (iNOS) by lipopolysaocharide or endotoxin from a gram-negative bacterium bas been known to be deleterious to a gastric mucosa. In the present shady, to elucidate the physiological action of H.pylori LPS on gastric mucosa and the role of NO, we were carried out both in vivo and in vitro study by employing E.coli LPS as a control.1. IT pylori LPS was isolated from gram-order bacteria by the phenol-water extraction method, and then further purified by tine enzymatic digestion of RNA, DNA, and proteins.2. In vitro cross talk between products from iNOS and cyclooxygenase (COX) in the rat gastric mucosa during endotoxemia was examined in vivo. The results demonstrate that in the E cob LPS-treated rat gastric mucosa, PGE2, a COX product, enhances after activation of iNOS. The effect of COX activity on iNOS-NO pathway is important in the regulation of gastric mucosal integrity inflammatory states.3. We further elucidated the interaction of LPS with gastric epithelial cells by using a normal mouse gastric surface mucous cell line (GSM06). Our findings suggest that both LPSs from H.pylori and E.coli induce the iNOS and Toll-like receptor (TLR) 2 through the TLR 4 expressed constitutively in GSM06. This mechanism on TLR 2 induction can be crucial for maintenance of gastric mucosal integrity.