The role of quorum sensing system in Helicobacter pylori infection

群体感应（QS）是一种调节细菌表型的细胞间通讯系统，包括毒力因子基因的表达。幽门螺杆菌与人类和一些实验动物的胃疾病有关，并具有luxS/ 2型自诱导（AI-2）系统。我们研究了一个特定的luxS突变对幽门螺杆菌特征的影响。在0.3%琼脂培养基上，幽门螺杆菌HPKY08 （luxS::cat）的活力显著低于野生型幽门螺杆菌TK1402。luxs补充菌株HPKY21表现出与幽门螺杆菌TK1402相当的运动性。结果表明，luxS/M-2系统在幽门螺杆菌运动中起重要作用。与野生型亲本菌株TK1402相比，luxS突变体在蒙古沙鼠模型中表现出较低的感染率。在口服接种3个月后，用qRT-PCR检测到luxS突变体感染沙鼠的幽门螺杆菌数量低于tk1402感染沙鼠。在其他致病因素上，对胃上皮细胞的粘附、耐酸性、巨噬细胞样细胞的存活率，野生型与突变株之间无显著差异。电镜下观察到两株菌株均有3-5根极性鞭毛。利用对数期两株菌株的mRNA进行DNA微阵列分析，突变菌株中包含鞭毛相关基因在内的53个基因的表达量比野生型菌株高1.5倍以上。在固定期，通过qRT-PCR检测luxS突变体flaA和flaB的表达量低于野生型。通过2D-SDS分析，luxS突变株的FlaB含量明显低于野生型菌株。

Quorum sensing (QS) is a cell-to-cell communication system that regulates bacterial phenotypes, including the expression of virulence factor genes. Helicobacter pylori is associated with gastric disorders in humans and some experimental animals, and possesses the luxS/type 2 autoinducer (AI-2) system. We examined the effects of a specific luxS mutation on the characteristics of H. pylori. On 0.3% agar medium, motility of H. pylori HPKY08 (luxS::cat) was significantly lower than that of wild-type H. pylori TK1402. The luxS-complemented strain HPKY21 exhibited motility comparable to that of H. pylori TK1402. It was shown that the luxS/M-2 system plays an important role in H. pylori motility. The luxS mutant exhibited a reduced infection rate relative to the wild-type parent strain TK1402 in a Mongolian gerbil model. At 3 months after oral inoculation, lower numbers of H. pylori were detected by qRT-PCR in luxS mutant-infected gerbils than in TK1402-infected gerbils. On other pathogenesis factor, adherence to gastric epithelial cells, acid tolerance, survival rate in macrophage like-cells, there was no significant differences between wild type and mutant strains. In both strains, 3-5 polar flagella were observed on electron microscopy. In DNA micro-array using mRNA of both strains at logarithmic phase, 53 genes including flagella associated gene in mutant strain which was 1.5 or more fold expression comparing with wild type strain. In stationary phase, lower expression data of flaA and flaB in luxS mutant than that in wild type by qRT-PCR. By 2D-SDS analysis amount of FlaB in luxS mutant strain was lower than that in wild type strain, significantly.