Search

To develop a safe and efficient Aβ vaccine for Alzheimer's disease, we constructed a plasmid DNA vaccine encoding ten repeats of Aβ3–10 and three copies of C3d-p28 as a molecular adjuvant and administered it intramuscularly in 12-month-old female Tg-APPswe/PSEN1dE9 mice. Therapeutic immunization with p(Aβ3–10)10-C3d-p28.3 stimulated a Th2 immune response that elicited therapeutic levels of anti-Aβ antibodies and improved cognitive function. In addition, the vaccine reduced the cerebral Aβ burden and astrocytosis without increasing the incidence of microhemorrhage. Our results indicate that the p(Aβ3–10)10-C3d-p28.3 vaccine is a promising immunotherapeutic option for Aβ vaccination in Alzheimer's disease.

Immunization with synthetic amyloid β-protein (Aβ) peptide has resulted in preventing and clearing Aβ deposits as well as improving cognitive function in transgenic mouse models of Alzheimer's disease (AD). But similar immunization studies in humans were halted due to the risk of inducing T cell-mediated meningoencephalitis. A safe and effective vaccine for AD requires not only therapeutic levels of anti-Aβ antibodies but also the prevention of an adverse T cell-mediated, proinflammatory autoimmune response. In this study, we developed a DNA vaccine, p(Aβ(3-10))(10)-IL-4, encoding ten tandem repeats of Aβ(3-10) fused with mouse cytokine interleukin-4 (IL-4) as a molecular adjuvant. Wild-type mice were injected intramuscularly with p(Aβ(3-10))(10)-IL-4 followed by in vivo electroporation. The p(Aβ(3-10))(10)-IL-4 vaccine elicited high titer anti-Aβ antibodies which bound to Aβ plaque in brain tissue from a ten-month-old APP/PS1 transgenic mouse. The antibody isotype was mainly IgG(1) and the IgG(1)/IgG(2a) ratio in the p(Aβ(3-10))(10)-IL-4 group was approximately eight times greater than that of the Aβ(42) group. Ex vivo cultured splenocytes isolated from mice immunized with p(Aβ(3-10))(10)-IL-4 exhibited a low IFN-γ response and a high IL-4 response compared with the control group. These results indicate that immunization with the p(Aβ(3-10))(10)-IL-4 vaccine induced effective anti-Aβ antibodies and elicited a Th2-polarized immune response that had a lower potential to cause an inflammatory T cell response. Thus, the DNA vaccine, p(Aβ(3-10))(10)-IL-4, may be a safe and efficient vaccine for AD.

The aggregation of amyloid β-peptide (Aβ) is thought to play a pivotal role in the disease progression of Alzheimer’s disease (AD). Amyloid β directed immunotherapy has been considered an alternative AD treatment. In this study, we constructed a DNA vaccine, p(Aβ3–10)10-mIL-4, encoding ten tandem repeats of Aβ3–10 fused with mouse IL-4. Eight-month-old APP/PS1 transgenic mice were injected intramuscularly with p(Aβ3–10)10-mIL-4 followed by in vivo electroporation. Immunization with the vaccine induced high-titer anti-Aβ antibodies and attenuated the behavior impairment. Immunoglobulin isotyping revealed a predominantly IgG1 response and ex vivo cultured splenocytes exhibited a low IFN-γ and high IL-4 response, indicating a Th2 anti-inflammatory response. Immunohistochemical analysis revealed that p(Aβ3–10)10-mIL-4 immunization decreased Aβ deposition, and the microglial attraction significantly decreased accompanied by the clearance of Aβ. There was no microhemorrhage in the brain of the immunized mice. These results suggest that the immunization potentially reduced the inflammation in brain of transgenic mice and therefore improved their cognitive ability. This novel DNA vaccine p(Aβ3–10)10-mIL-4 may be an effective immunization method as therapy for AD.

To develop a safe and efficient vaccine for AD treatment, we constructed an adenovirus vector vaccine encoding ten repeats of Aβ3-10 and CpG motif as a molecular adjuvant. We demonstrated that therapeutic immunization with Ad-10 × Aβ3-10–CpG elicits Aβ3-10 specific Th2-polarized immune response with high titers of anti-Aβ antibodies in APPswe/PSEN1dE9 mice, which in turn reduced Aβ deposits in brains and cognitive impairment. In addition, Ad-10 × Aβ3-10–CpG reduced astrocytosis without increasing the incidence of microhemorrhage. Our findings of this study raise the possibility that the adenovirus vaccine Ad-10 × Aβ3-10–CpG would be a safe and effective alternative for AD immunotherapy.

Three-month-old Alzheimer's disease model transgenic mice were immunized with Aβ 1-42 , Plp-Adenovirus [Ad]-X-CMV-(Aβ 3-10 ) 10 -CpG [AdCpG-(Aβ 3-10 ) 10 ] or AdCpG virus fluid via nasal mucosal inhalation, respectively. ELISA analysis of serum showed Aβ 42 antibody titers were significantly increased in mice immunized with Aβ 1-42 and AdCpG-(Aβ 3-10 ) 10 . Concanavalin A and AdCpG-(Aβ 3-10 ) 10 stimulation significantly increased the number of proliferating spleen cells cultured from AdCpG(Aβ 3-10 ) 10 and Aβ 42 groups compared with the control group. In the AdCpG(Aβ 3-10 ) 10 group, levels of interleukin (IL)-4 and IL-10 were increased, while those of IL-2 and interferon-γ were decreased. In the Aβ 42 group, levels of IL-4, IL-10, IL-2 and interferon-γ were all increased. Experimental findings indicate that AdCpG-(Aβ 3-10 ) 10 vaccine can produce strong T helper 2 (Th2) humoral immune responses in addition to the production of Aβ 42 antibody. The cellular immunologic response was weak and avoided Aβ 1-42 -mediated cytotoxicity.