佐剂LTN增强新型CVB3黏膜疫苗病毒性心肌炎保护效果的机制探讨

Mechanism of enhanced viral-myocarditis-prophylactic effect of a novel coxsackievirus B3 mucosal vaccine by LTN adjuvant

目的 对黏膜佐剂淋巴细胞趋化因子（LTN）的机制进行初步探讨.方法 共凝聚法制备chitosan-pLTN和chitosan-pVP1复合物,混合后隔周滴鼻免疫小鼠,共4次,每次每种质粒50μg.末次免疫后2周以3LD50 CVB3腹腔感染小鼠诱导病毒性心肌炎,7 d后行心肌病理学观察.同时检测脾脏、肠系膜淋巴结（MLN）和颈部淋巴结（CLN）部位T细胞免疫应答、DC比例及CD86的表达.结果 LTN共免疫明显改善了CVB3性病毒性心肌炎炎症损伤;显著促进了脾脏、CLN和MLN部位特异性T细胞增殖和分泌IFN-γ的能力,显著上调了DC比例和DC表面共刺激分子CD86的表达.结论 黏膜佐剂LTN通过促进局部DC的招募和成熟来增强全身和黏膜部位特异性T细胞免疫应答,进而增强CVB3病毒性心肌炎黏膜基因疫苗的免疫保护效果.

Objective To explore the mechanism of lymphotactin（LTN） to exert mucosal adjuvant activity. Methods Complexes of chitosan-pVP1 and chitosan-pLTN were seperately prepared by co-cojugation method, then 50μg（DNA） of each complex was administered intranasally to male BALB/c mice 4times biweekly. Two weeks after the final immunization, mice were challenged with 3LD50 CVB3 to cause viral myocarditis, heart histopathological changes were examined 7 days later. Meanwhile, T cell immune responses, DC percentage and its membrane CD86 expression were monitored in spleen, mesenteric lymph node（MLN） and cervical lymph node（CLN）. Results Co-immunizaiton with LTN remarkbly alleviated CVB3-induced cardial injury. This improvement was accompanied with enhanced T cell proliferation and IFN-γ-secreting ability, increased DC frequency and membrane CD86 expression both in spleen and mucosal draining lymph nodes（ MLN, CLN）. Conclusion LTN exerts its mucosal adjuvant function in augmenting specific T cell immune responses systemically and mucosally via DC enrichment in spleen, MLN and CLN and up-regulation of DC maturation.