Qu Baoxi, Rosenberg Roger N, Li Liping, Boyer Philip J, Johnston Stephen A
Center for Biomedical Inventions, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, 5232 Harry Hines Boulevard, Dallas, TX 75390-9036, USA.
Arch Neurol. 2004 Dec;61(12):1859-64. doi: 10.1001/archneur.61.12.1859.
The amyloid-beta (Abeta) peptide has a central role in the neurodegeneration of Alzheimer disease (AD). Immunization of AD transgenic mice with Abeta(1-42) (Abeta(42)) peptide reduces both the spatial memory impairments and AD-like neuropathologic changes in these mice. Therapeutic immunization with Abeta in patients with AD was shown to be effective in reducing Abeta deposition, but studies were discontinued owing to the development of an autoimmune, cell-mediated meningoencephalitis. We hypothesized that gene vaccination could be used to generate an immune response to Abeta(42) that produced antibody response but avoided an adverse cell-mediated immune effect.
To develop an effective genetic immunization approach for treatment and prevention of AD without causing an autoimmune, cell-mediated meningoencephalitis.
Mice were vaccinated with a plasmid that encodes Abeta(42), administered by gene gun. The immune response of the mice to Abeta(42) was monitored by measurement of (1) antibody levels by enzyme-linked immunosorbent assay (ELISA) and Western blot and (2) Abeta(42)-specific T-cell response as measured by interferon-gamma enzyme-linked immunospot (ELISPOT) assay.
Gene-gun delivery of the mouse Abeta(42) dimer gene induced significant humoral immune responses in BALB/c wild-type mice after 3 vaccinations in 10-day intervals. All 3 mice in the treated group showed significant humoral immune responses. The ELISPOT assay for interferon-gamma release with mouse Abeta(42) peptide and Abeta(9-18) showed no evident cytotoxic T-lymphocyte response. We further tested the responses of wild-type BALB/c mice to the monomer Abeta(42) gene vaccine. Western blot evaluation showed both human and mouse Abeta monomer gene vaccine elicited detectable humoral immune responses. We also introduced the human Abeta(42) monomer gene vaccine into AD double transgenic mice APPswe/PSEN1(A246E). Mice were vaccinated with plasmids that encode Abeta(1-42) and Abeta(1-16), or with plasmid without the Abeta gene. Treated mice showed significant humoral immune responses as demonstrated by ELISA and by Western blot. These mice also showed no significant cellular immune response as tested by ELISPOT. One of the treated mice was killed at 7 months of age for histological observations, and scattered amyloid plaques were noted in all layers of the cerebral cortex and in the hippocampus in both Abeta(42)- and control-vaccinated mice. No definite difference was discerned between the experimental and control animals.
Gene-gun-administered genetic immunization with the Abeta(42) gene in wild-type BALB/c and AD transgenic mice can effectively elicit humoral immune responses without a significant T-cell-mediated immune response to the Abeta peptide. This immunotherapeutic approach could provide an alternative active immunization method for therapy and prevention of AD.
β-淀粉样蛋白（Aβ）肽在阿尔茨海默病（AD）的神经退行性变中起核心作用。用Aβ（1-42）（Aβ（42））肽免疫AD转基因小鼠可减轻这些小鼠的空间记忆障碍和AD样神经病理变化。在AD患者中用Aβ进行治疗性免疫已被证明可有效减少Aβ沉积，但由于自身免疫性细胞介导的脑膜脑炎的发生，研究已停止。我们假设基因疫苗接种可用于产生针对Aβ（42）的免疫反应，该反应可产生抗体反应，但避免不良的细胞介导免疫效应。
开发一种有效的基因免疫方法，用于治疗和预防AD，而不会引起自身免疫性细胞介导的脑膜脑炎。
用基因枪给予编码Aβ（42）的质粒对小鼠进行疫苗接种。通过（1）酶联免疫吸附测定（ELISA）和蛋白质印迹法测量抗体水平，以及（2）通过干扰素-γ酶联免疫斑点（ELISPOT）测定法测量Aβ（42）特异性T细胞反应，监测小鼠对Aβ（42）的免疫反应。
以10天的间隔进行3次疫苗接种后，基因枪递送小鼠Aβ（42）二聚体基因在BALB/c野生型小鼠中诱导了显著的体液免疫反应。治疗组的所有3只小鼠均表现出显著的体液免疫反应。用小鼠Aβ（42）肽和Aβ（9-18）进行的干扰素-γ释放的ELISPOT测定未显示明显的细胞毒性T淋巴细胞反应。我们进一步测试了野生型BALB/c小鼠对单体Aβ（42）基因疫苗的反应。蛋白质印迹评估显示，人源和鼠源Aβ单体基因疫苗均引发了可检测到的体液免疫反应。我们还将人Aβ（42）单体基因疫苗引入AD双转基因小鼠APPswe/PSEN1（A246E）。用编码Aβ（1-42）和Aβ（1-16）的质粒或不含Aβ基因的质粒对小鼠进行疫苗接种。ELISA和蛋白质印迹显示，治疗后的小鼠表现出显著的体液免疫反应。ELISPOT检测显示，这些小鼠也没有明显的细胞免疫反应。在7个月龄时处死1只治疗后的小鼠进行组织学观察，在接种Aβ（42）和对照疫苗的小鼠的大脑皮质各层和海马中均发现散在的淀粉样斑块。实验动物和对照动物之间未发现明显差异。
在野生型BALB/c和AD转基因小鼠中，用基因枪进行Aβ（42）基因的基因免疫接种可有效引发体液免疫反应，而对Aβ肽没有显著的T细胞介导免疫反应。这种免疫治疗方法可为AD的治疗和预防提供一种替代的主动免疫方法。
