Effect and Potential Mechanism of Immunotherapy on Cognitive Deficits in Animal Models of Alzheimer's Disease: A Systematic Review and Meta-Analysis

Objective: Immunotherapy has been reported to ameliorate Alzheimer's disease (AD) in the animal model; however, the immunologic approaches and mechanisms have not been specifically described. Thus, the systematic review and meta-analysis were conducted to explore the effect and potential mechanism of immunotherapy on AD animal experiments based on behavioral indicators. Methods: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Cochrane Collaboration guidelines and the inclusion/exclusion criteria of immunotherapy in animal studies, 15 studies were systematically reviewed after extraction from a collected database of 3,742 publications. Finally, the effect and mechanism of immunotherapy on AD models were described by performing multiple subgroup analyses. Results: After immunotherapy, the escape latency was reduced by 18.15 seconds and the number of crossings over the platform location was increased by 1.60 times in the Morris Water Maze. Furthermore, compared to the control group, active and passive immunization could markedly ameliorate learning and memory impairment in 3 pound Tg AD animal models, and active immunization could ameliorate the learning and memory ability of the APPswe/PS1DE9 D E9 AD animal model. Meanwhile, it could be speculated that cognitive dysfunction was improved by immunotherapy, perhaps mainly via reducing A,B40, ,B 40, A,B42, ,B 42, and Tau levels, as well as increasing IL-4 levels. Conclusion: Immunotherapy significantly ameliorated the cognitive dysfunction of AD animal models by assessing behavioral indicators.