Shin-ei Matsumoto

Long-term oral lithium treatment attenuates motor disturbance in tauopathy model mice: implications of autophagy promotion.

Lithium, a drug used to treat bipolar disorders, has a variety of neuroprotective mechanisms including inhibition of glycogen synthase kinase-3 (GSK-3), a major tau kinase. Recently, it has been shown that, in various neurodegenerative proteinopathies, lithium could induce autophagy. To analyze how lithium is therapeutically beneficial in tauopathies, transgenic mice overexpressing human mutant tau (P301L) were treated with oral lithium chloride (LiCl) for 4 months starting at the age of 5 months. At first, we examined the effects of treatment on behavior (using a battery of behavioral tests), tau phosphorylation (by biochemical assays), and number of neurofibrillary tangles (NFTs) (by immunohistopathology). In comparison with control mice, LiCl-treated mice showed a significantly better score in the sensory motor tasks, as well as decreases in tau phosphorylation, soluble tau level, and number of NFTs. Next, we examined lithium effects on autophagy using an antibody against microtubule-associated protein 1 light chain 3 (LC3) as an autophagosome marker. The number of LC3-positive autophagosome-like puncta was increased in neurons of LiCl-treated mice. Neurons containing NFTs were completely LC3-negative, whereas LC3-positive autophagosome-like puncta contained phosphorylated-tau (p-tau). The protein level of p62 was decreased in LiCl-treated mice. These data suggested that oral long-term lithium treatment could attenuate p-tau-induced motor disturbance not only by inhibiting GSK-3 but also by enhancing autophagy in tauopathy model mice.

Chronic intermittent hypoxia/reoxygenation facilitate amyloid-β generation in mice.

Previous studies have shown a high prevalence of obstructive sleep apnea (OSA) among patients with Alzheimers disease (AD). However, it is poorly assessed whether chronic intermittent hypoxia (CIH), which is a characteristic of OSA, affects the pathophysiology of AD. We aimed to investigate the direct effect of intermittent hypoxia (IH) in pathophysiology of AD in vivo and in vitro. In vivo, 15 male triple transgenic AD mice were exposed to either CIH or normoxia (5% O2 and 21% O2 every 10 min, 8 h/day for 4 weeks). Amyloid-β (Aβ) profile, cognitive brain function, and brain pathology were evaluated. In vitro, human neuroblastoma SH-SY5Y cells stably expressing wild-type amyloid-β protein precursor were exposed to either IH (8 cycles of 1% O2 for 10 min followed by 21% O2 for 20 min) or normoxia. The Aβ profile in the conditioned medium was analyzed. CIH significantly increased levels of Aβ42 but not Aβ40 in the brains of mice without the increase in hypoxia-inducible factor 1, alpha subunit (HIF-1α) expression. Furthermore, CIH significantly increased intracellular Aβ in the brain cortex. There were no significant changes in cognitive function. IH significantly increased levels of Aβ42 in the medium of SH-SY5Y cells without the increase in the HIF-1α expression. CIH directly and selectively increased levels of Aβ42 in the AD model. Our results suggest that OSA would aggravate AD. Early detection and intervention of OSA in AD may help to alleviate the progression of the disease.

Region-Specific Vulnerability to Oxidative Stress, Neuroinflammation, and Tau Hyperphosphorylation in Experimental Diabetes Mellitus Mice

Recent epidemiological evidence suggests that diabetes mellitus (DM) is a risk factor for Alzheimers disease (AD). One of the pathological hallmarks of AD is hyperphosphorylated tau protein, which forms neurofibrillary tangles. Oxidative stress and the activation of inflammatory pathways are features that are associated with both DM and AD. However, the brain region specificity of AD-related neurodegeneration, which mainly occurs in the hippocampus while the cerebellum is relatively unaffected, has not yet been clarified. Therefore, we used experimental DM mice (caused by an intraperitoneal injection of streptozotocin [STZ]) to determine whether these neurodegeneration-associated mechanisms were associated with region-specific selective vulnerability or tau phosphorylation. The hippocampus, midbrain, and cerebellum of aged (14 to 18 months old) non-transgenic (NTg) and transgenic mice overexpressing wild-type human tau (Tg601 mice) were evaluated after a treatment with STZ. The STZ injection increased reactive oxygen species, lipid peroxidation markers such as 4-hydroxynonenal and malondialdehyde in the hippocampus, but not in the midbrain or cerebellum. The STZ treatment also increased the number of Iba-1-positive and CD68-positive microglial cells, astrocytes, and IL-1β, IL-6, IL-10, and IL-18 levels in the hippocampus, but not in the midbrain or cerebellum. Tau hyperphosphorylation was also enhanced in the hippocampus, but not in the midbrain or cerebellum. When the effects of STZ were compared between Tg601 and NTg mice, microglial proliferation and elevations in IL-6 and phosphorylated tau were higher in Tg601 mice. These results suggest that neuroinflammation and oxidative stress in STZ-treated mice are associated with tau hyperphosphorylation, which may contribute to selective neurodegeneration in human AD.

Short-term treadmill exercise increased tau insolubility and neuroinflammation in tauopathy model mice.

Physical exercise has been identified as a preventive measure for Alzheimers disease (AD), one of the neuropathological hallmarks of which, neurofibrillary tangles, consist of hyperphosphorylated insoluble tau. Previous studies demonstrated that long-term treadmill exercise reduced tau hyperphosphorylation and insolubility; however, whether short-term treadmill exercise (STE) alters tau modifications currently remains unknown. In the present study, we attempted to characterize the effects of STE on tau solubility and determine its relationship with neuroinflammation using tauopathy model mice (Tg601), which express wild-type human tau. The results obtained showed that 3 weeks of non-shock treadmill exercise in Tg601 and non-transgenic female mice markedly increased insoluble tau. An analysis of phosphorylation patterns indicated that changes in tau solubility were related to an increase in phosphorylation at the tau C-terminal end. The results of immunohistochemical analyses revealed that STE increased the number of Iba-1-positive microglial cells in the hippocampus. Elevations in the levels of the lipid peroxidation markers, 4-hydroxy-trans-2-noneal and malondialdehyde, indicated the presence of oxidative stress. Moreover, higher levels of cytokines, IL-1β and IL-18, and chemokines, CXCL-1 and CXCL-12, supported neuroinflammation.

A rapid screening and production method using a novel mammalian cell display to isolate human monoclonal antibodies

Antibody display methods are increasingly being used to produce human monoclonal antibodies for disease therapy. Rapid screening and isolation of specific human antibody genes are valuable for producing human monoclonal antibodies showing high specificity and affinity. In this report, we describe a novel mammalian cell display method in which whole human IgG is displayed on the cell surface of CHO cells. Cells expressing antigen-specific human monoclonal IgGs with high affinity on the cell surface after normal folding and posttranscriptional modification were screened using a cell sorter. The membrane-type IgG-expressing CHO cells were then converted to IgG-secreting cells by transfection with a plasmid coding Cre recombinase. This mammalian cell display method was applied to in vitro affinity maturation of monoclonal C9 IgG specific to the human high-affinity IgE receptor (FcεRIα). The CDR3 of the C9 heavy chain variable region gene was randomly mutated and inserted into pcDNA5FRT/IgG. A C9 IgG (CDRH3r)-expressing CHO cell display library consisting of 1.1×10(6) independent clones was constructed. IgG-displaying cells showing high reactivity to FcεRIα antigen were screened by the cell sorter, resulting in the establishment of a CHO cell line producing with higher reactivity than the parent C9 IgG.

Urinary Homocysteic Acid Levels Correlate with Mini-Mental State Examination Scores in Alzheimer's Disease Patients

Homocysteic acid (HA) has been suggested as a pathogen in a mouse model of Alzheimers disease (AD), 3xTg-AD. However, it is not established whether HA is involved in humans. We investigated the relationship between urinary HA levels and Mini-Mental State Examination (MMSE) scores in AD patients (n = 70) and non-AD controls (n = 34). We found a positive, statistically significant relationship between the two variables (the urinary HA level and MMSE score) (r = 0.31, p = 0.0008, n = 70). This relationship was stronger in females than males (r = 0.43, p = 0.005, n = 44 in females; r = 0.48, p = 0.02, n = 22 in males). The urinary HA levels were significantly different in AD patients than controls (AD: 8.7 ± 7.5, n = 70; non-dementia control: 13.3 ± 9.4, n = 34, p < 0.01). In addition, aging and smoking were found as lowering factors for urinary HA levels. Our preliminary study showed a negative, statistically significant relationship between blood HA (micromole) and urine HA levels (r = -0.6, p = 0.007, n = 19), and between blood HA levels and MMSE scores (r = -0.79, p = 0.0000518, n = 19). On the basis of these results, we speculate that reduced urinary excretion induces elevated HA levels in blood, resulting in cognitive dysfunctions. This study also suggests that HA may be a candidate of neurotoxins for uremic encephalopathy. Since amyloid-β increases HA toxicity and HA is an agonist of N-methyl-D-aspartic acid (NMDA) receptor, we speculate that elevated blood HA affects the brain cognitive function through NMDA receptor-mediated toxicity in AD.

Involvement of the Septo-Hippocampal Cholinergic Pathway in Association with Septal Acetylcholinesterase Upregulation in a Mouse Model of Tauopathy

BACKGROUND Cholinergic cell loss in the basal forebrain, the major source of hippocampal cholinergic projections, has been implicated in Alzheimers disease. OBJECTIVE To examine whether the septohippocampal pathway is involved in tauopathy model mice and to elucidate the tau-associated mechanism underlying cholinergic alteration. METHODS Adult (6 to 8 months old) and old (16 to 18 months old) transgenic mice expressing wild-type human tau, Tg601, were examined using Ex vivo diffusion tensor magnetic resonance imaging (DTI) and 2-[18F]fluoro- 2-deoxy-D-glucose positron emission tomography (FDG-PET). Choline acetyltransferase (ChAT)-positive neurons in the medial septum (MS) were counted by stereological methods. Acetylcholinesterase (AChE) activity and AChE mRNA in 6 brain regions were measured. RESULTS Ex vivo DTI revealed that the number of fractional anisotropy (FA) streamlines in the septohippocampal tract decreased with age in Tg601 mice. The FA value in the septum was lower in old Tg601 mice than in non-tg mice. A voxel-based statistical analysis of FDG-PET revealed the presence of low glucose uptake areas, involving the MS in adults, and spread over regions including the hippocampal dentate gyrus in old mice. In the MS, the number of choline acetyltransferase (ChAT)-positive neurons decreased in old Tg601 mice. AChE activity and AChE mRNA T transcripts were exclusively higher in the septum. CONCLUSION The upregulation of AChE in the septum may result in the selective degeneration of the septohippocampal cholinergic pathway in the tauopathy mouse model.

Lithium Ameliorates Motor Disturbance by Enhancing Autophagy in Tauopathy Model Mice

Lithium has been shown to upregulate the clearance of misfolded proteins in neurodegenerative disease including huntingtin, α-synuclein, and pathological prion protein, by enhancing autophagy. In vitro studies have demonstrated that tau could also be degraded in the autophagic pathway, as well as by the ubiquitin-proteasome system. Recently, we reported that oral long-term lithium treatment reduced motor disability in tauopathy model mice (Tau-tg). Our double-labeling immunohistochemical analysis of the spinal cord of Tau-tg mice demonstrated that phosphorylated tau was internalized into LC3-positive autophagosomes. Interestingly, thioflavin-S-positive neurofibrillary tangles were not stained by anti-LC3 antibody. Therefore, it was likely that soluble phosphorylated tau was degraded in autophagosomes while insoluble aggregated tau remained. After reviewing the literature, we propose the possibility that autophagy-enhancing signaling mechanisms may differ between brain regions.

Truncated tau causes microtubule disassembly with aging in tauopathy model mice

P4-045 TRUNCATED TAU CAUSES MICROTUBULE DISASSEMBLY WITH AGING IN TAUOPATHY MODEL MICE Shin-ei Matsumoto, Taiki Kambe, Yumiko Motoi, Koichi Ishiguro, Yukako Hasegawa, Takeshi Tabira, Fuyuki Kametani, Masato Hasegawa, Nobutaka Hattori, Juntendo University School of Medicine, Tokyo, Japan; Juntendo University School of Medicine, Tokyo, Japan; Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan. Contact e-mail: shimatsu@juntendo.ac.jp

Oral vaccine using viral vectors for Alzheimer's disease: PIB/PET studies in old cynomolgus monkeys

dissolved in phosphate-buffered saline strongly evokes the antibody response to phage particles. 2) This response was dependent on MyD88 signaling. 3) A few copies of Abeta42 fibril mimotope-displaying phage clone induce anti-Abeta42 conformer antibody response in C57BL/6 and J20 mice Conclusions: B6-phage may provide a promising vaccination strategy for immunotherapy of Alzheimer’s diseasewithout the involvement of Abeta42-specific T cell immunity since the safety of bacteriophage for human has been investigated in a number of studies of phage therapy.