幽门螺杆菌热休克蛋白60脂质体疫苗的制备及其免疫预防作用

Preparation oral liposome-encapsulated recombinant Helicobacter pylori heat shock protein 60 vaccine for prevention of Hp infection

目的探讨制备脂质体包裹重组幽门螺杆菌(Hp)热休克蛋白60(Hsp60)口服疫苗的方法,并用Hp感染的小鼠模型评价其在预防Hp感染中的作用。方法将PET-22(+)/Hsp60在BL21(DE3)大肠杆菌表达,Ni-NTA琼脂糖树脂纯化Hsp60重组蛋白,用薄膜分散法制备以卵磷脂和胆固醇为膜组分包裹的Hsp60重组蛋白口服疫苗,并用透射电镜测定其粒径。75只BALB/C小鼠分为5组,分别通过灌胃方法给予PBS、空白脂质体、Hsp60重组蛋白+霍乱霉素(CT)、脂质体包裹Hsp60重组蛋白、脂质体包裹Hsp60重组蛋白+CT,每周1次共4次,末次攻击2周再用活Hp攻击3次,3周后处死小鼠,行胃组织快速尿素酶试验、Hp的定植半定量、炎症程度及其炎症活动度的评分。结果可溶性表达产物占全菌总蛋白的27%,经纯化获得纯度为95%的重组蛋白,制备的脂质体粒径为(0.7±0.4)μm。PBS组和空白脂质体组保护率均为0,而Hsp60重组蛋白+CT组、脂质体包裹Hsp60重组蛋白组、脂质体包裹Hsp60重组蛋白+CT组的保护率分别为73.3%、66.7%和86.7%,且均能使免疫小鼠胃粘膜Hp感染数目明显减少,炎症反应减轻。结论口服脂质体能分地代替免疫佐剂,作为Hp疫苗的免疫佐剂,将具有广泛的应用前景。

Objective To prepare oral liposome-encapsulated recombinant Helicobacter pylori (Hp) heat shock protein 60 (Hsp60) vaccine and investigate its effect against Hp infection in mice. Methods The recombinant vector PET-22(+)/Hsp60 was transformed into BL21(DE3) E.coli. The recombinant protein was purified with Ni-NTA agrose resin and the oral liposome-encapsulated vaccine was prepared with phosphatidyl choline and cholesterols using film method, with the size distribution of the folate liposomes measured by transimssion electronic microscopy. BALB/c mice were divided into 5 groups and immunized by intragastric administration of PBS, liposome, rHsp60 plus choleratoxin (CT), liposome-encapsulated rHsp60, and liposome-encapsulated rHsp60 plus CT, respectively, given once a week for 4 weeks. All the mice were challenged by Hp for 3 times within two weeks following the last immunization and sacrificed 3 weeks after the last challenge. Hp detection was performed by fast urease test. Semi-quantitative assessment of the bacterial colonization density observation of the inflammation severity and gastric histopathology were carried out. Results The soluble expression product accounted for 27% of the total bacterial protein. The purity of recombinant fusion protein was about 95% after purification. The mean size of the folate liposomes was 0.7±0.4 μm. PBS or liposome alone showed no immune-enhancing effect, and rHsp60 plus CT, liposome-encapsulated rHsp60 and liposome-encapsulated rHsp60 plus CT had the protective rates against Hp infection of 73.3%, 66.7% and 86.7%, respectively. The latter 3 preparations effected significantly reduced Hp infection and alleviated the inflammation in the gastric mucosa of the mice challenged with Hp. Conclusion The oral liposome may serve as a potential adjuvant for Hp vaccine in preventing Hp infection.