Active Immunization with DNA Vaccine Reduced Cerebral Inflammation and Improved Cognitive Ability in APP/PS1 Transgenic Mice by In Vivo Electroporation

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.