幽门螺杆菌cagA蛋白及其疫苗候选抗原对T细胞Fas Ligand介导凋亡的调节作用

目的　评价幽门螺杆菌 (Hp)多种功能蛋白致T细胞凋亡的能力 ,以探求它们在Fas/FasL介导的机体T细胞耐受中的作用 ,为Hp疫苗研制寻求安全有效的免疫原。方法　应用JAM技术对cagA阳性Hp及同源基因突变株、重组尿素酶、粘附素HpaA及外膜蛋白Hop2 5、35、38致T细胞系凋亡的能力进行了比较 ;应用流式细胞术对上述因素特别是cagA阳性菌株诱导T细胞FasL表达的能力进行了检测 ;应用金属蛋白酶抑制剂和蛋白合成抑制剂分别提高和降低Hp介导的T细胞凋亡 ,以证实其与FasL合成的关系。结果　HpcagA阳性株无论在提高T细胞表达FasL还是在诱导T细胞凋亡方面的作用均强于同源基因突变株。Hp抗原制品中尿素酶对T细胞无杀伤能力 ,而Hop38毒性最强 ,Hop2 5、Hop35和HpaA等作用较弱。金属蛋白酶抑制剂提高了cagA阳性Hp致T细胞凋亡的能力 ,而蛋白合成抑制剂Emetine则通过抑制T细胞FasL表达而抑制了Hp介导的T细胞凋亡。结论　cagA蛋白及Hop38能通过调节FasL表达造成T细胞耐受 ;尿素酶、外膜蛋白Hop2 5、Hop35和HpaA不会通过抑制T细胞而导致耐受机制的发生 ,因而可安全应用于疫苗研制。

The evaluation of cagA and other vaccine candidate proteins of Helicobacter pylori on T cell apoptosis mediated by Fas/Fas ligand interaction

Objective To evaluate the effect of several surface proteins of Helicobacter pylori ( H. pylori ) on inducing apoptosis of T cells through the modulation of Fas/Fas ligand (FasL) interaction and to provide information on the screen of safe and effective immunogen for H. pylori vaccine. Methods T cell apoptosis induced by cagA and isogenic cagA knockout strain, recombinant urease, HpaA and outer membrane proteins, Hop25, Hop35 and Hop38 was detected by JAM assay. Flow cytometry was used to evaluate the increase in FasL expression on T cells under the stimulation of these bacterial proteins. Metalloprotease inhibitor, 1, 10-Phenanthroline (PHE) and protein synthesis inhibitor, emetine, were used to change the activity of FasL to confirm the association of FasL with H. pylori mediated killing toward T cells. Results The effect of cagA H.pylori was stronger in both the induction of apoptosis and FasL expression of T cells than that of cagA knockout strain. H. pylori urease could not kill T cell, while Hop38 had the strongest effect among the tested H. pylori proteins on the induction of T cell apoptosis through increasing FasL expression. Metaloprotease inhibitor could increase the killing of T cells induced by H. pylori because of its ability to prevent the cleavage of membrane bound FasL protein. On the other hand, emetine could decrease H. pylori mediated killing by inhibiting of FasL synthesis on T cells. Conclusion cagA and Hop38 protein might be involved in the negative regulation of T cell growth through upregulating FasL expression urease and other Hop proteins tested might be safe and effective to be used as the antigens for H. pylori vaccine.