Active Amyloid-β Vaccination Results in Epigenetic Changes in the Hippocampus of an Alzheimer’s Disease-Like Mouse Model

Promising tacrine/huperzine A-based dimeric acetylcholinesterase inhibitors for neurodegenerative disorders: From relieving symptoms to modifying diseases through multitarget

Neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, are devastating diseases in the elderly world, which are closely associated with progressive neuronal loss induced by a variety of genetic and/or environmental factors. Unfortunately, currently available treatments for neurodegenerative disorders can only relieve the symptoms but not modify the pathological processes. Over the past decades, our group by collaborating with Profs. Yuan-Ping Pang and Paul R. Carlier has developed three series of homo/hetero dimeric acetylcholinesterase inhibitors derived from tacrine and/or huperzine A. The representative dimers bis(3)-Cognitin (B3C), bis(12)-hupyridone, and tacrine(10)-hupyridone might possess disease-modifying effects through the modulation of N-methyl-d-aspartic acid receptors, the activation of myocyte enhancer factor 2D gene transcription, and the promotion of neurotrophic factor secretion. In this review, we summarize that the representative dimers, such as B3C, provide neuroprotection against a variety of neurotoxins via multiple targets, including the inhibitions of N-methyl-d-aspartic acid receptor with pathological-activated potential, neuronal nitric oxide synthase, and β-amyloid cascades synergistically. More importantly, B3C might offer disease-modifying potentials by activating myocyte enhancer factor 2D transcription, inducing neuritogenesis, and promoting the expressions of neurotrophic factors in vitro and in vivo. Taken together, the novel dimers might offer synergistic disease-modifying effects, proving that dimerization might serve as one of the strategies to develop new generation of therapeutics for neurodegenerative disorders.

High Methionine Diet-Induced Alzheimer's Disease like Symptoms Are Accompanied by 5-Methylcytosine Elevated Levels in the Brain

Background

Excessive or insufficient intake of methionine (Met) causes neuronal dysfunction, neurodegeneration, cerebrovascular dysfunction, vascular leakage, and short-term memory loss, which result in the occurrence of Alzheimer's disease- (AD-) like symptoms.

Objective

To determine the relationship between high methionine diets (HMD) induced AD-like symptoms and 5-methylcytosine (5-mC) level.

Methods

C57BL/6J mice were randomly divided into two groups: the control group (Maintain diets) and the model group (2% HMD). Mice were fed with 2% HMD for 9 weeks. Animals were weighed and food intake was recorded weekly. Open field test, nesting ability test, Y maze test, new object recognition test, and Morris water maze test were used to detect the motor, learning, and memory ability. Hematoxylin-eosin (HE) staining was used to observe the damage of cells in hippocampus and cortex. Immunofluorescence (IF) staining was used to detect the expression and distribution of amyloid-β 1-40 (Aβ_1-40), amyloid-β 1-42 (Aβ_1-42), and 5-methylcytosine (5-mC) in hippocampus and cortex. Western blotting (WB) was used to determine the expression of Aβ and DNA methyltransferases- (DNMTs-) related proteins in the cortex. Enzyme-linked immunosorbent assay (ELISA) was performed to detect homocysteine (Hcy) level (ELISA).

Results

Feeding of HMD decreased the body weight and food intake of mice. Behavioral testing revealed that HMD caused learning, memory, and motor ability impairment in the mice. HE staining results showed that HMD feeding caused damage of hippocampal and cortical neurons, along with disordered cell arrangement, and loss of neurons. Furthermore, HMD increased the contents of Aβ_1-40, Aβ_1-42, and 5-mC in the hippocampus and cortex. WB results showed that HMD increased the expression of Aβ production-related proteins, such as amyloid precursor protein (APP) and beta-secretase 1 (BACE1), and decreased the expression of Aβ metabolism-related protein in the cortex, including insulin-degrading enzyme (IDE) and neprilysin (NEP). Additionally, the decreased expression of DNA methyltransferase1 (DNMT1) was observed in HMD-treated mice, but there was no significant change of DNMT3a level. ELISA results showed that HMD increased the levels of Hcy in serum.

Conclusion

Our result suggested that the HMD can cause neurotoxicity, leading to AD-like symptoms in mice, which may be related to 5-mC elevated.

Effect of Different Aβ Aggregates as Antigen on the Measure of Naturally Occurring Autoantibodies against Amyloid-β40/42 in IVIG

BACKGROUND

The specific Intravenous Immunoglobulin (IVIG) for Alzheimer's Disease (AD) is developing, which contains a high level of naturally occurring autoantibodies against amyloid-β (nAbs-Aβ), and the measure of nAbs-Aβ content is greatly essential. Though Enzyme-Linked Immunosorbent Assay (ELISA) has been widely used in detecting the nAbs-Aβ content, the impact of Aβ aggregates species chosen as antigen in ELISA on this measure has not been evaluated.

OBJECTIVE

To clarify the influence of different Aβ40/42 aggregates as antigen during ELISA on the content of nAbs-Aβ40/42 measured in IVIG.

METHOD

Preparation of various Aβ40/42 aggregates was performed by different aggregation solutions and various lengths of time, and analyzed by western blot. Different Aβ40/42 aggregates as antigen were adopted to measure the nAbs-Aβ40/42 content in IVIG by ELISA, and the control was carried out to reduce interference of nonspecific binding. The Bonferroni and Dunnett's T3 were used for statistical analysis.

RESULTS

The duration for the formation of Aβ40/42 aggregates had more effect on detecting nAbs-Aβ40/42 content in IVIG than the aggregation solution. Higher content of nAbs-Aβ40/42 in the same IVIG was displayed when measured with Aβ40/42 aggregates at day 3, instead of at day 0.5 and day 7.0. The nAbs- Aβ40/42 contents in the same IVIG measured with Aβ40/42 aggregates prepared in different solutions were obviously different, but there was no significant regularity among them.

CONCLUSION

The nAbs-Aβ40/42 content in the same IVIG is significantly different when measured with Aβ40/42 aggregated under different conditions. The nAbs-Aβ40/42 content in IVIG by antigen-dependent measures, like ELISA, is uncertain.