衰老对流感疫苗诱导体液和细胞免疫的影响及机制
发布时间：2018-08-28 10:11
【摘要】： 流感病毒是一种对人类健康和公共卫生威胁很大的病毒,每年全球有很多人由于流感病毒感染致病或死亡。其中老年人对流感病毒的抵抗力尤为低下,更易受到流感病毒感染及其诱发的并发症导致的住院及死亡。因而迫切需要研究能够特别适合老年人应用的安全有效的流感疫苗。阐明免疫衰老的原因,从而启示和惠及其他老年疫苗的开发和应用。 本研究利用昆虫杆状病毒表达系统共表达H1N1流感病毒A/Perto Rico/8/34的HA,NA和M1蛋白,在体外组装成流感病毒样颗粒(Virus-like particles, VLPs)。经鉴定和纯化的VLPs保持了与流感病毒粒子相似的形态大小以及表面糖蛋白的正常生物学活性。低剂量VLPs免疫的成年及老年小鼠与灭活流感病毒(Inactivated influenza virus, IIV)相比显示相同的免疫原性,均能够保护被免疫小鼠在致死流感病毒攻击中存活。但是老年小鼠的保护效果明显劣于成年小鼠,表现为老年小鼠体重下降程度大于成年小鼠以及攻毒后体内活跃的高水平的抗原特异性CD8 T细胞反应。增大免疫剂量能显著加强疫苗在老年小鼠中的免疫保护效果,表现为攻毒中轻微的可以忽略不计的体重下降以及攻毒后与成年小鼠相当的低水平的CD8 T细胞反应。 虽然流感病毒VLPs能对被免疫老年小鼠提供完全保护,但是其并不能取得像成年小鼠一样良好的保护效果。这样的结果激起了我们对免疫衰老机制研究的兴趣。与其他文献报道相似,在实验中我们发现老年小鼠体内的调节性T细胞(T regulatory cells, Treg)含量显著高于成年小鼠Treg细胞约2倍之多。因为Treg细胞对免疫系统的调节性作用,我们推测这部分累积的Treg细胞可能是造成老年小鼠接种后疫苗免疫反应性低下的原因之一。因此在免疫小鼠前,我们给小鼠腹腔注射CD25的单克隆抗体以暂时消除Treg细胞。实验结果非常确实的显示了消除Treg细胞能够极大提高老年小鼠的特异性疫苗免疫反应,并对老年小鼠提供完美的免疫保护力。实验结果证明了老年小鼠体内积累的Treg细胞是造成其免疫反应低下的主要原因之一。 在阐明了老年小鼠免疫衰老的可能机制后,我们对老年小鼠进行了一次免疫攻毒保护试验。以观察是否消除Treg细胞能够提高疫苗一次免疫的保护成功率。实验结果再一次证实了Treg细胞对调节老年小鼠免疫反应的重要性:注射过CD25抗体的免疫老年小鼠在大剂量致死流感病毒攻击中全部存活且体重鲜有下降,而没有注射过CD25抗体的老年小鼠仅有67%存活,且存活个体有明显的发病症状和体重降低。 本研究结果证明昆虫杆状病毒生产的流感病毒VLPs在老年小鼠中具有和IIV疫苗相等同的免疫保护效力。VLPs具有能够刺激树突状细胞—专职抗原递呈细胞产生细胞因子的能力。流感病毒VLPs代表了一种新型流感疫苗策略,能够对成年和老年小鼠提供更有效的免疫保护效力,因而具有非常广阔的应用前景。本研究同时阐明,小鼠免疫衰老的潜在机制——即Treg细胞的累积性增多是造成老年小鼠免疫力低下的主要原因之一。免疫接种前暂时性消除Treg细胞能够极大恢复老年小鼠被抑制的免疫反应,增强疫苗免疫诱导的体液和细胞免疫反应。针对Treg细胞的疫苗研发策略为今后老年疫苗的研究和开发提供了新思路和可能的靶向及解决方案。
[Abstract]:Influenza virus is a kind of virus that threatens human health and public health. Many people all over the world suffer or die from influenza virus infection every year. Safe and effective influenza vaccines that are especially suitable for the elderly. To clarify the causes of immune aging, and thus inspire and benefit the development and application of other vaccines for the elderly.
In this study, the HA, NA and M1 proteins of H1N1 influenza virus A/Perto Rico/8/34 were co-expressed by insect baculovirus expression system and assembled into influenza virus-like particles (VLPs) in vitro. The VLPs identified and purified maintained the similar morphology and size as influenza virus particles and the normal biological activity of surface glycoproteins. Compared with inactivated influenza virus (IIV), adult and aged mice immunized with low dose of VLPs showed the same immunogenicity and could protect the immunized mice from lethal influenza virus attack. Higher levels of antigen-specific CD8 T cells were active in adult mice and in vivo after challenge. Increasing the dose of the vaccine significantly enhanced the immune protective effect of the vaccine in the aged mice, which showed slight negligible weight loss during attack and low levels of CD8 T cells after challenge.
Although influenza virus VLPs can provide complete protection to immunized aged mice, they can not achieve as good protection as adult mice. This result arouses our interest in the study of the mechanism of immune aging. Because Treg cells regulate the immune system, we speculate that this accumulation of Treg cells may be one of the causes of the decreased immune response in the vaccinated aged mice. Monoclonal antibodies were used to temporarily eliminate Treg cells. The results showed that eliminating Treg cells could greatly improve the specific immune response of the aged mice and provide perfect immune protection for the aged mice. One of the main reasons.
After elucidating the possible mechanism of immune senescence in aged mice, we conducted an immune challenge protection test in aged mice to see if eliminating Treg cells could increase the success rate of vaccine immunization. The immunized mice survived the lethal attack of influenza viruses at high doses with little weight loss, while only 67% of the aged mice without CD25 antibody survived, and the survivors had significant symptoms and weight loss.
The results of this study demonstrated that the influenza virus VLPs produced by insect baculovirus have the same immune protective effect as the IIV vaccine in the aged mice. VLPs have the ability to stimulate the production of cytokines by dendritic cells-specialized antigen-presenting cells. Influenza virus VLPs represent a novel influenza vaccine strategy that can be used for adulthood and development This study also elucidates that the cumulative increase of Treg cells, the underlying mechanism of immune senescence in mice, is one of the major causes of immunodeficiency in older mice. Temporary elimination of Treg cells before vaccination can greatly restore immunity. Inhibited immune responses in aged mice enhance the humoral and cellular immune responses induced by vaccines. Vaccine development strategies for Treg cells provide new ideas and possible targets and solutions for future research and development of vaccines for the aged.
【学位授予单位】：中国农业科学院
【学位级别】：博士
【学位授予年份】：2009
【分类号】：R392
本文编号：2209081
[Abstract]:Influenza virus is a kind of virus that threatens human health and public health. Many people all over the world suffer or die from influenza virus infection every year. Safe and effective influenza vaccines that are especially suitable for the elderly. To clarify the causes of immune aging, and thus inspire and benefit the development and application of other vaccines for the elderly.
In this study, the HA, NA and M1 proteins of H1N1 influenza virus A/Perto Rico/8/34 were co-expressed by insect baculovirus expression system and assembled into influenza virus-like particles (VLPs) in vitro. The VLPs identified and purified maintained the similar morphology and size as influenza virus particles and the normal biological activity of surface glycoproteins. Compared with inactivated influenza virus (IIV), adult and aged mice immunized with low dose of VLPs showed the same immunogenicity and could protect the immunized mice from lethal influenza virus attack. Higher levels of antigen-specific CD8 T cells were active in adult mice and in vivo after challenge. Increasing the dose of the vaccine significantly enhanced the immune protective effect of the vaccine in the aged mice, which showed slight negligible weight loss during attack and low levels of CD8 T cells after challenge.
Although influenza virus VLPs can provide complete protection to immunized aged mice, they can not achieve as good protection as adult mice. This result arouses our interest in the study of the mechanism of immune aging. Because Treg cells regulate the immune system, we speculate that this accumulation of Treg cells may be one of the causes of the decreased immune response in the vaccinated aged mice. Monoclonal antibodies were used to temporarily eliminate Treg cells. The results showed that eliminating Treg cells could greatly improve the specific immune response of the aged mice and provide perfect immune protection for the aged mice. One of the main reasons.
After elucidating the possible mechanism of immune senescence in aged mice, we conducted an immune challenge protection test in aged mice to see if eliminating Treg cells could increase the success rate of vaccine immunization. The immunized mice survived the lethal attack of influenza viruses at high doses with little weight loss, while only 67% of the aged mice without CD25 antibody survived, and the survivors had significant symptoms and weight loss.
The results of this study demonstrated that the influenza virus VLPs produced by insect baculovirus have the same immune protective effect as the IIV vaccine in the aged mice. VLPs have the ability to stimulate the production of cytokines by dendritic cells-specialized antigen-presenting cells. Influenza virus VLPs represent a novel influenza vaccine strategy that can be used for adulthood and development This study also elucidates that the cumulative increase of Treg cells, the underlying mechanism of immune senescence in mice, is one of the major causes of immunodeficiency in older mice. Temporary elimination of Treg cells before vaccination can greatly restore immunity. Inhibited immune responses in aged mice enhance the humoral and cellular immune responses induced by vaccines. Vaccine development strategies for Treg cells provide new ideas and possible targets and solutions for future research and development of vaccines for the aged.
【学位授予单位】：中国农业科学院
【学位级别】：博士
【学位授予年份】：2009
【分类号】：R392
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