Beta-amyloid(Abeta) immunization as vaccines has now become a promising approach for the prevention and treatment of Alzheimer's disease (AD)after its debut in 1999. Transgenic mouse models of AD that develop age-dependent Abeta deposition, damage to the neuropil, and behavioral deficits have enabled researchers to test if the approach can influence these AD-like pathologic changes in their brains. Active immunization with different forms of A beta and protocols have been shown to decrease brain Abeta deposition and improve cognitive performance in these mice models in the following studies. Although the phase II clinical trials of active immunization with Abeta(AN1792)were halted last year due to the occurrence of CNS inflammation in a small subset of patients, researchers found that strong humoral responses can be induced by the vaccination. Furthermore, the active immunization also brings an almost complete clearance of Abeta from much of the cerebral cortex. Abeta specific antibodies are believed to cross blood-brain barrier by minimal destroy of vascular wall where amyloid depositions exist. Three possible mechanisms on removal of Abeta deposition from brain have also been reviewed. Still some problems should be clarified before this strategy could be applied for clinical therapy. Whether vaccination will improve the cognitive decline in AD patients will depend upon clinical assessments, which was vital to destiny of the approach.
Alzheimer Disease ; immunology ; Amyloid beta-Peptides ; immunology ; Animals ; Humans ; Vaccines ; immunology

Alzheimer's disease (AD) is the most common cause of dementia in elderly population. There are two hallmark pathological lesions: the intracellular neurofibrillary tangles (NFTs) and the extracellular amyloid deposits in the senile plaques (SP). The NFTs are aggregates of hyperphosphorylated microtubule Tau protein. The amyloid deposits in the SP are the beta-amyloid (Abeta) peptides-Abeta40 and Abeta42. The Abeta peptides are derived from the amyloid precursor protein (APP) which is considered very important for the AD pathogenesis. In recent years, studies have focused on understanding the generation of Abeta peptides by the alpha-, beta- and gamma- secretase activity on APP, as cause and progression of both familial and sporadic AD (FAD and SAD). This review covers the trafficking and processing of APP, the amyloid cascade hypothesis in AD pathogenesis, the mutations in the genes encoding APP, PS1 and PS2 of early-onset and late-onset AD. The risk factor apolipoprotein E (ApoE) for AD and therapeutic anti-beta-amyloid vaccination strategies for prevention of AD are also discussed.
Alzheimer Disease ; genetics ; metabolism ; pathology ; therapy ; Alzheimer Vaccines ; immunology ; Amyloid beta-Peptides ; antagonists & inhibitors ; genetics ; immunology ; metabolism ; Amyloid beta-Protein Precursor ; genetics ; metabolism ; Animals ; Apolipoproteins E ; genetics ; Humans ; Immunotherapy, Active ; Membrane Proteins ; genetics ; Peptide Fragments ; genetics ; Plaque, Amyloid ; pathology ; Presenilin-1 ; Presenilin-2

BACKGROUNDAmyloid β(1-42) (Aβ(42)) peptide vaccination has been proved to be effective in reducing amyloid burden in brain and improving cognitive function in Alzheimer's disease (AD) mouse models. But the phase II trial of Aβ(42) peptide vaccine was halted because of T cell-mediated meningoencephalitis. In this study, a DNA vaccine, p(Aβ(3-10))(10)-CpG, was constructed to test whether it would induce predominant T(H)2 immune response upon immunization of BALB/c mice.

METHODSBALB/c mice were vaccinated intramuscularly with p(Aβ(3-10))(10)-CpG plasmids. Aβ(42) peptide, pcDNA3.1(+) empty vector and PBS were injected to the control groups. Expression of interesting gene in injected muscle was identified by immunohistochemistry. Anti-Aβ antibody titers, isotype profiles as well as cytokines in ex vivo splenocytes culture supernatants were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTSP(Aβ(3-10))(10)-CpG plasmid was expressed in muscle after injection detected by immunohistochemistry. The p(Aβ(3-10))(10)-CpG vaccine induced high titers of anti-Aβ antibodies in BALB/c mice. And isotype of the antibodies was mainly IgG1, the IgG1/IgG2a ratio for the p(Aβ(3-10))(10)-CpG group was approximately 5 times greater than that for the Aβ(42) peptide group. Ex vivo cultured splenocytes isolated from mice immunized with p(Aβ(3-10))(10)-CpG exhibited high interleukin-4 response and low interleukin-γ (IFN-γ) response.

CONCLUSIONSImmunization with p(Aβ(3-10))(10)-CpG vaccine primarily induces a T(H)2 type of response, thus reduces the probability of inflammation. This p(Aβ(3-10))(10)-CpG vaccine possesses the basic factors required for a safe and effective AD vaccine.

Alzheimer Disease ; immunology ; therapy ; Amyloid beta-Peptides ; immunology ; Animals ; Cells, Cultured ; Enzyme-Linked Immunosorbent Assay ; Immunity, Humoral ; immunology ; Immunoglobulin G ; metabolism ; Immunohistochemistry ; Interferon-gamma ; metabolism ; Interleukin-4 ; metabolism ; Mice ; Mice, Inbred BALB C ; Muscles ; metabolism ; T-Lymphocytes ; immunology ; Vaccines, DNA ; therapeutic use

OBJECTIVE: To construct a recombinant prokaryoticexpression plasmid pET/ c-Aβ(15)-c, and evaluate the immunogenicity of its encoded fusion protein as expressed in E.coli. METHODS: The gene fragment HBc88-144 was amplified by PCR and subcloned to pUC19. The synthetic, double-strand Aβ(1-15) gene was inserted downstream of HBc1-71 in pGEMEX/c1-71. After restriction enzyme digestion, c1-71- Aβ(15) was spliced to HBc88-144, yielding the recombinant gene c-Aβ(15)-c; that gene was subcloned into pET-28a(+). The fusion protein (CA15C) expressed in the transformed E.coli BL21 was induced with isopropyl β-D-1-thiogalactopyranoside (IPTG) and analyzed by SDS-PAGE. The virus-like particle (VLP) formed by fusion protein CA15C was observed with transmission electric microscope (TEM). Four Kunming (KM) mice were given intraperitoneal injections of CA15C, and the anti-Aβ antibody elicited was detected by indirect ELISA. RESULTS: The sequence of the recombinant gene was confirmed by restriction enzyme digestion and DNA sequencing. After IPTG induction, the fusion protein was expressed, mainly in the sediment from the bacterial lysate. The expression level was 40% of total protein in the sediment. The CA15C could form VLP. After 5 rounds of immunization, the titer of anti-Aβ antibody in the sera of KM mice reached 1:10000, while the anti-HBc antibody was undetectable. CONCLUSION Recombinant c-Aβ(15)-c gene can be expressed in E.coli. The expressed protein can form VLPs and has a strong immunogenicity.
Alzheimer Disease ; prevention & control ; Amyloid beta-Peptides ; genetics ; Animals ; Base Sequence ; Genetic Vectors ; genetics ; Hepatitis B Core Antigens ; genetics ; immunology ; Humans ; Mice ; Molecular Sequence Data ; Peptide Fragments ; genetics ; Recombinant Fusion Proteins ; genetics ; immunology ; metabolism ; Vaccines, Virus-Like Particle ; genetics ; immunology ; metabolism