Therapeutic Strategies for Alzheimer's Disease in the View of Diabetes Mellitus.

Recently, Alzheimer's disease (AD) is understood as "diabetes of the brain" or "type 3 diabetes." Recent clinical trials of anti-amyloid ß-protein (Aß) therapies have not proved to be successful. Thus, glucose-insulin metabolism in the brain is thought to be an alternative therapeutic target. Various types of antidiabetic drugs such as insulin, thiazolidinediones, dipeptidyl peptidase-4 (DPP4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists, biguanides, and others have been reported to be effective on cognitive impairment in animal models and patients with DM or AD. Here, recent reports are reviewed. While we identified apomorphine (APO) as a novel drug that promoted intracellular Aß degradation and improved memory function in an AD mouse model, more recently, we have revealed that APO treatment improves neuronal insulin resistance and activates insulin-degrading enzyme (IDE), a major Aß-degrading enzyme. In this context, recovery of impaired insulin signaling in AD neurons may be a promising therapeutic strategy for AD dementia.

Multiphasic acute disseminated encephalomyelitis associated with atypical rubella virus infection.

We report the first case of an occurrence of multiphasic acute disseminated encephalomyelitis (ADEM) associated with atypical rubella virus infection with no rash and long-term increased titers of serum anti-rubella IgM in a 17-year-old male who had no history of rubella vaccination. He suffered from at least six clinical exacerbations with disseminated hyperintense lesions on FLAIR MR images during the course of 18 months. Repeated methylprednisolone pulse therapy and intravenous immunoglobulin therapy resolved the exacerbations. In patients with multiphasic ADEM of unknown etiology, clinicians should also consider the possibility of preceding infection with rubella virus.

Activation of glutathione peroxidase and inhibition of p53-related apoptosis by apomorphine.

Apomorphine hydrochloride (APO) is known to be a dopamine receptor agonist, and has recently been found to be a novel drug for Alzheimer's disease (AD). We found that APO treatment ameliorated oxidative stress in an AD mouse model and specifically attenuated the hydrogen peroxide-induced p53-related apoptosis in the SH-SY5Y neuroblastoma cell line. To further understand the mechanism behind this action, we investigated the actions of APO on intracellular redox systems, such as the glutathione cycle and catalase. We studied the effects of specific inhibitors for glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (BCNU, MCS, and ATZ, respectively) on the effects of APO. Treatments with MCS or BCNU, but not ATZ, significantly attenuated the protective effects of APO. Interestingly, APO treatment elevated GPx activity, but did not increase the expression of the GPx1 protein. Although BCNU treatment attenuated APO effects, GR activity was not elevated by APO treatment. The same effects were observed in primary neuronal cultures. In addition, treatment with dopamine D1, D2, D3 and D4 receptor antagonists did not counteract the protective action of APO. Thus, APO may enhance GPx activity through dopamine receptor-independent pathways.

Apomorphine treatment in Alzheimer mice promoting amyloid-ß degradation.

OBJECTIVE: Intracellular amyloid ß-protein (Aß) contributes to neurodegeneration in Alzheimer disease (AD). Apomorphine (APO) is a dopamine receptor agonist for Parkinson disease and also protects against oxidative stress. Efficacy of APO for an AD mouse model and effects of APO on cell cultures are studied. METHODS: The triple transgenic AD mouse model (3xTg-AD) has 2 familial AD-related gene mutations (APP(KM670/671NL) /PS1(M146V)) and a tau gene mutation (Tau(P301L)). Six-month-old 3xTg-AD mice were treated with subcutaneous injections of APO once a week for 1 month. Memory function was evaluated by Morris water maze before and after the treatment. Brain tissues were examined by immunohistochemical staining and Western blotting. Effects of APO on intracellular Aß degradation, activity of Aß-degrading enzymes, and protection against oxidative stress were studied in cultured SH-SY5Y cells. RESULTS: After APO treatment, short-term memory function was dramatically improved. Significant decreases in the levels of intraneuronal Aß, hyper-phosphorylated tau (p-tau), p53, and heme oxygenase-1 proteins were observed. Moreover, APO promoted degradation of intracellular Aß, increased activity of proteasome and insulin-degrading enzyme, protected against H(2) O(2) toxicity, and decreased p53 protein levels in the cultured cells. INTERPRETATION: 3xTg-AD mice show intraneuronal Aß accumulation and memory disturbances before extracellular Aß deposition. Our data demonstrating improvement of memory function of 3xTg-AD mice with decreases in intraneuronal Aß and p-tau levels by APO treatment strongly suggest that intraneuronal Aß is an important therapeutic target and APO will be a novel drug for AD.

[Intravascular lymphoma confirmed by brain biopsy, quickly treated by chemotherapy: a case report].

A 60-year-old female with intravascular lymphoma (IVL) presented with the complaint of urinary dysfunction and gait disturbance. T2 weighted MR imaging of the thoracic spinal cord showed a hyperintense lesion, and brain MR imaging indicated hyperintense lesions in the deep white matter. Multiple sclerosis was assumed, so steroid pulse therapy was administered. However, her level of consciousness decreased and her paraplegia progressed. Laboratory data showed that anemia and thrombocytopenia had worsened with high serum LDH and soluble IL-2 receptor levels. Biopsy of bone marrow indicated hypercellularity associated with hemophagocytic histiocytes, although no atypical lymphocytes were detected. Brain MR imaging indicated a new subcortical lesion in the left parietal lobe. One and a half months after admission, an open brain biopsy of the left parietal cortex was performed. Histopathological diagnosis was IVL, large B cell type. Immediately, she underwent CHOP therapy containing rituximab (R-CHOP therapy). After chemotherapy, spinal and brain MR images showed no new abnormal lesions. Clinically, it is difficult to make a diagnosis of IVL in life as it has no characteristic symptoms or radiological findings. Therefore, if a patient is suspected of having IVL, a biopsy of different organs, including brain, is necessary for making an early diagnosis and initiating chemotherapy.

Increase in p53 protein levels by presenilin 1 gene mutations and its inhibition by secretase inhibitors.

Presenilin 1 (PS1) gene mutations are the major causes of early-onset familial Alzheimer's disease and are known to increase amyloid-beta42 (Abeta42) production as well as to promote apoptosis. We have recently reported that intracellular Abeta42 activates p53 mRNA expression and promotes p53-dependent apoptosis. Here, we examined the p53 mRNA and protein levels in cells transfected with wild-type and I143T/G384A mutant PS1 genes. Although the baseline p53 mRNA levels remained unaltered, the p53 protein levels were significantly elevated in mutant PS1-transfected cells. Treatments with apoptosis-inducing agents induced significant elevation of the p53 protein but not p53 mRNA levels in mutant PS1-transfected cells. Treatment with a beta-secretase inhibitor and gamma-secretase inhibitor decreased the intracellular Abeta levels in amyloid-beta protein precursor (AbetaPP) and PS1-double transfected cells, and restrained upregulation of the p53 protein levels in the mutant PS1-transfected cells. Also, we found that proteasome activity was decreased in mutant PS1-transfected cells compared to wild-type PS1-transfected cells. Proteasome activity was further decreased in AbetaPP/PS1-double transfected cells. Taken together, p53-dependent apoptosis upregulated by the I143T/G384A mutant PS1 gene may be associated, at least in part, with intracellular Abeta and proteasome impairment.

Enhancement of activation of caspases by presenilin 1 gene mutations and its inhibition by secretase inhibitors.

Presenilin 1 (PS1) gene mutations are the major causes of early-onset familial Alzheimer's disease. Acceleration of apoptosis is one of the major pathogenic mechanisms of PS1 mutants, and PS1 mutants have also been reported to induce overproduction of amyloid-beta protein 42. Here, we investigated aberrancy in activation of initiator caspases related to two PS1 gene mutations, I143T and G384A. Acceleration of apoptosis, elevation of caspase-3/7 activity, and significant increases in caspase-4, -8 and -9 activities during apoptosis induced by several agents were found in these mutant PS1-transfected cells. Interestingly, thapsigargin treatment enhanced caspase-4 and -9 activities in I143T-mutant PS1-transfected cells, while hydrogen peroxide treatment enhanced caspase-4, -8 and -9 activities in G384A-mutant PS1-transfected cells, indicating diverse apoptosis-promoting effects of PS1 gene mutations. In addition, treatment with a beta-secretase inhibitor or gamma-secretase inhibitor significantly attenuated the effects of the PS1 mutants on caspase-3/7 activation and recovered cell viability. Our present data suggest that these PS1 mutants accelerate the activation of initiator caspases and promote apoptosis, which may be associated, at least in part, with amyloid-beta production.

[Inhibition of neuronal death by promoting degradation of intracellular amyloid beta-protein].

Inhibition of aggregation of amyloid p-protein (AP) and promotion of extracellular AM removal are known as potent therapeutic tools for Alzheimer's disease (AD). While, the importance of Af342 accumulating in neurons has recently been suggested, and we have reported that A/42 accumulating in the neurons moves into the nucleus, activating p53 mRNA expression and leading to apoptosis (Ohyagi et al, FASEB J, 2005). Moreover, intraneuronal Ap is reported to induce mitochondrial dysfunction via binding ABAD, synaptic pathology, and inhibition of proteasome. Thus, it is an alternative therapeutic tool to decrease the levels of A342 and p53 proteins in AD neurons. We established a human neuroblastoma (SH-SY5Y) cell culture system in which AV peptide is artificially accumulated in cytosol. We have found that apomorphine hydrochloride promotes degradation of intracellular AM and p53 attenuating oxidative stress-induced apoptosis. Using a proteasome activity assay method, one of the mechanisms is thought to be activation of proteasome. Similar anti-apoptotic effect was observed in the primary cultured neurons. Apomorphine hydrochloride is now used as a dopamine agonist for Parkinson's disease or an anti-ED drug in western countries, but also may be one of the candidate drugs to inhibit neuronal death in AD.

Intraneuronal amyloid beta42 enhanced by heating but counteracted by formic acid.

Amyloid beta-protein ending at 42 (Abeta42) is the major peptide deposited in Alzheimer's disease (AD) brain. In immunocytochemical studies, formic acid treatment is used to dramatically enhance Abeta immunoreactivity. Recently, Abeta42 has been reported to accumulate in AD neurons. Since heating is known to enhance intracellular protein immunoreactivity, we used an autoclaving protocol to enhance intraneuronal Abeta42 immunoreactivity. Using this protocol, both anti-Abeta42 N-terminal and C-terminal antibodies, but not anti-Abeta40 C-terminal antibody, labeled AD neurons. Moreover, formic acid treatment counteracted such effects of autoclaving. Thus, intraneuronal Abeta42 accumulation may have been underestimated by conventional methods using formic acid only.

Mapping of subcortical white matter abnormality in Alzheimer's disease using diffusion-weighted magnetic resonance imaging.

RATIONALE AND OBJECTIVES: White matter (WM) abnormality in Alzheimer's disease (AD) has been less well characterized than cortical damage. We studied the spatial distribution of the subcortical WM abnormality using diffusion-weighted magnetic resonance imaging (DWI). MATERIALS AND METHODS: Twenty-one AD patients and seven healthy, elderly subjects were included. DWIs were obtained using a cerebrospinal fluid (CSF)-nulled pulse sequence to reduce the partial volume contamination of CSF signal. Diffusivity in the subcortical WM voxels was mapped onto the cortical surface using original software so that the spatial distribution of subcortical WM damage, which was visualized as an area of increased diffusivity, could be viewed in a three-dimensional map. The damages in the lateral surface of the bilateral cerebral hemispheres were visually evaluated, and severities of the damages in five brain regions were compared with each other. In addition, the severity of the damage in each region was correlated with patient's mini-mental state examination (MMSE) score. RESULTS: In both hemispheres, clear sparing of the pericentral regions and predominant involvement of the parietal and temporal regions were revealed with statistical significance (P < .05, respectively). Marginal correlation (P < .05 uncorrected for multiple comparisons) was observed between the damage severity in the bilateral frontal and right temporal regions and patient's MMSE score. CONCLUSION: We demonstrated a subcortical WM abnormality over the parietal and temporal regions with clear sparing of the pericentral region using our mapping method, which supported the hypothesis that the subcortical WM abnormality in AD originates in Wallerian degeneration.

Intracellular Abeta42 activates p53 promoter: a pathway to neurodegeneration in Alzheimer's disease.

The amyloid beta-protein (Abeta) ending at 42 plays a pivotal role in Alzheimer's disease (AD). We have reported previously that intracellular Abeta42 is associated with neuronal apoptosis in vitro and in vivo. Here, we show that intracellular Abeta42 directly activated the p53 promoter, resulting in p53-dependent apoptosis, and that intracellular Abeta40 had a similar but lesser effect. Moreover, oxidative DNA damage induced nuclear localization of Abeta42 with p53 mRNA elevation in guinea-pig primary neurons. Also, p53 expression was elevated in brain of sporadic AD and transgenic mice carrying mutant familial AD genes. Remarkably, accumulation of both Abeta42 and p53 was found in some degenerating-shape neurons in both transgenic mice and human AD cases. Thus, the intracellular Abeta42/p53 pathway may be directly relevant to neuronal loss in AD. Although neurotoxicity of extracellular Abeta is well known and synaptic/mitochondrial dysfunction by intracellular Abeta42 has recently been suggested, intracellular Abeta42 may cause p53-dependent neuronal apoptosis through activation of the p53 promoter; thus demonstrating an alternative pathogenesis in AD.