淋巴细胞趋化因子增强柯萨奇病毒DNA疫苗黏膜免疫及预防小鼠心肌炎的作用

Enhancement of the mucosal immune responses and prophylactic effect of a novel coxsackievirus B3-specific mucosal DNA vaccine by co-administration of lymphotactin

本研究在已建立的柯萨奇病毒B3型(CVB3)黏膜疫苗chitosan-pVP1基础上,引入C家族趋化因子,即淋巴细胞趋化因子(LTN),以期诱导更强的黏膜免疫应答,获得更有效的免疫保护作用。将pLTN与pVP1各50μg混合后,与chitosan形成共聚复合物,隔周滴鼻免疫小鼠,共4次;末次免疫后2周,检测血清IgG、粪便IgA及肠系膜淋巴结细胞毒性T淋巴细胞(CTL)活性。同时,以3LD50/0.1mlCVB3腹腔感染小鼠,7d后检测血清肌酸激酶(CK)活性及心肌病理学改变。结果显示,与对照组相比,chi-(pVP1+pLTN)可显著提高CVB3特异性血清IgG水平、粪便IgA水平以及增强肠系膜淋巴结特异性CTL应答。病毒攻击后,chi-(pVP1+pLTN)组心肌炎发病率仅为16.7%,显著低于chi-(pVP1+pcDNA3.1)组的33.3%。心肌组织病理显示,chi-(pVP1+pLTN)组心外膜下仅有轻微炎症,而chi-(pVP1+pcDNA3.1)组除心外膜下有较多淋巴细胞聚集外,心肌内尚有少量炎症浸润和坏死灶。结果提示,LTN与VP1质粒经chitosan共包装后进行滴鼻免疫,可增强CVB3特异性黏膜免疫应答,更有效地预防病毒性心肌炎的发生。

The goal of this study was to improve the mucosal immune responses and protection against coxsackievirus B3 （CVB3）,using our previously prepared chitosan-pVP1 mucosal vaccine combined with a plasmid encoding lymphotactin （pLTN）,which is a C family chemokine.The final vaccine formulation chi-（pVP1＋pLTN） was prepared by conjugating chitosan with a mixture of pVP1 and pLTN （50 μg each）.Male BALB/c mice were immunized four times biweekly.Two weeks after the final immunization,the levels of CVB3-specific serum IgG,fecal IgA,and mucosal cytotoxic T lymphocyte （CTL） activity were quantified.Following a challenge with 3 LD50/0.1 ml CVB3,serum creatine kinase （CK） activity and histopathological changes in heart tissue were determined.Compared with the control group,immunization with chi-（pVP1＋pLTN） significantly increased the levels of CVB3-specific serum IgG and fecal IgA,and enhanced mucosal CTL activity.The incidence of myocarditis in mice receiving chi-（pVP1＋pLTN） was 16.7%,which was significantly lower than the 33.3% observed in mice receiving control formulation chi-（pVP1＋pcDNA3.1）.Histopathological analysis showed that there were fewer inflammatory cells under the epicardium in the hearts of co-immunized mice compared with control mice.In conclusion,intranasal co-administration of a LTN plasmid via chitosan nanoparticle could enhance CVB3-specific mucosal immune responses and provide more efficient protection against CVB3-induced myocarditis.