Uno Kaname, Kato Katsuaki, Atsumi Tomoaki, Suzuki Takehito, Yoshitake Jun, Morita Hidetoshi, Ohara Shuichi, Kotake Yashige, Shimosegawa Tooru, Yoshimura Tetsuhiko
Research Project of Biofunctional Reactive Species, Yamagata Promotional Organization for Industrial Technology, Yamagata, Japan.
Am J Physiol Gastrointest Liver Physiol. 2007 Nov;293(5):G1004-12. doi: 10.1152/ajpgi.00096.2007. Epub 2007 Sep 13.
Cell-surface Toll-like receptors (TLRs) initiate innate immune responses, such as inducible nitric oxide synthase (iNOS) induction, to microorganisms' surface pathogens. TLR2 and TLR4 play important roles in gastric mucosa infected with Helicobacter pylori (H. pylori), which contains lipopolysaccharide (LPS) as a pathogen. The present study investigates their physiological roles in the innate immune response of gastric epithelial cells to H. pylori-LPS. Changes in the expression of iNOS, TLR2, and TLR4, as well as downstream activation of mitogen-activated protein kinases and nuclear factor-kappaB (NF-kappaB), were analyzed in normal mouse gastric mucosal GSM06 cells following stimulation with H. pylori-LPS and interferon-gamma. Specific inhibitors for mitogen-activated protein kinases, NF-kappaB, and small interfering RNA for TLR2 or TLR4 were employed. The immunohistochemistry of TLR2 was examined in human gastric mucosa. H. pylori-LPS stimulation induced TLR2 in GSM06 cells, but TLR4 was unchanged. TLR2 induction resulted from TLR4 signaling that propagated through extracellular signal-related kinase and NF-kappaB activation, as corroborated by the decline in TLR4 expression on small interfering RNA treatment and pretreatment with inhibitors. The induction of iNOS and the associated nitric oxide production in response to H. pylori-LPS stimulation were inhibited by declines in not only TLR4 but also TLR2. Increased expression of TLR2 was identified in H. pylori-infected human gastric mucosa. TLR4 signaling initiated by H. pylori-LPS and propagated via extracellular signal-regulated kinase and NF-kappaB activation induced TLR2 expression in gastric epithelial cells. Induced TLR2 cooperated with TLR4 to amplify iNOS induction. This positive correlation may constitute a mechanism for stimulating the innate immune response against various bacterial pathogens, including H. pylori-LPS.
细胞表面的Toll样受体（TLRs）启动先天性免疫反应，例如诱导型一氧化氮合酶（iNOS）的诱导，以应对微生物表面病原体。TLR2和TLR4在感染幽门螺杆菌（H. pylori）的胃黏膜中发挥重要作用，幽门螺杆菌含有脂多糖（LPS）作为病原体。本研究调查了它们在胃上皮细胞对幽门螺杆菌-LPS的先天性免疫反应中的生理作用。在用幽门螺杆菌-LPS和干扰素-γ刺激后，分析了正常小鼠胃黏膜GSM06细胞中iNOS、TLR2和TLR4的表达变化，以及丝裂原活化蛋白激酶和核因子-κB（NF-κB）的下游激活情况。使用了丝裂原活化蛋白激酶、NF-κB的特异性抑制剂以及针对TLR2或TLR4的小干扰RNA。在人胃黏膜中检测了TLR2的免疫组织化学。幽门螺杆菌-LPS刺激在GSM06细胞中诱导了TLR2，但TLR4没有变化。TLR2的诱导是由通过细胞外信号相关激酶和NF-κB激活传播的TLR4信号引起的，小干扰RNA处理和抑制剂预处理导致TLR4表达下降证实了这一点。不仅TLR4的下降，而且TLR2的下降都抑制了对幽门螺杆菌-LPS刺激的iNOS诱导和相关一氧化氮的产生。在幽门螺杆菌感染的人胃黏膜中发现TLR2表达增加。幽门螺杆菌-LPS启动并通过细胞外信号调节激酶和NF-κB激活传播的TLR4信号在胃上皮细胞中诱导了TLR2表达。诱导的TLR2与TLR4协同作用以放大iNOS诱导。这种正相关可能构成了一种刺激针对包括幽门螺杆菌-LPS在内的各种细菌病原体的先天性免疫反应的机制。
