28, Number 3, February 2012
Sangmook Lee, Vanessa Doulames, Michelle Donnelly, James Levasseaur, Thomas B. Shea
Environmental Enrichment Can Prevent Cognitive Decline Induced by Dietary Oxidative Challenge
Abstract: Alzheimer’s disease encompasses multiple risk factors; convergence may be necessary for clinical manifestation. Mice received a complete diet or one lacking folate and vitamin E and containing iron as a pro-oxidant, in a standard environment (SE) or a large cage containing objects to stimulate exploration/activity (enriched environment; EE). Mice declined in maze navigation on the deficient versus complete diet in the SE but not the EE. Mice on the complete diet demonstrated superior performance in the EE versus SE. The EE reduced brain lipid and protein oxidation. These findings suggest that maintaining nutrition and activity may delay age-related cognitive decline.
Martha Dlugaj, Marcus Gerwig, Natalia Wege, Johannes Siegrist, Klaus Mann, Martina Bröcker-Preuß, Nico Dragano, Susanne Moebus, Karl-Heinz Jöckel, Beate Bokhof, Stefan Möhlenkamp, Raimund Erbel, Christian Weimar on behalf of the Heinz Nixdorf Recall Study Investigative Group
Elevated Levels of High-Sensitivity C-Reactive Protein are Associated with Mild Cognitive Impairment and Its Subtypes: Results of a Population-Based Case-Control Study
Abstract: As high-sensitivity C-reactive protein (hsCRP) seems to be associated with an increased risk of cognitive decline, this nested case-control study examined the relation of hsCRP and mild cognitive impairment (MCI) at different time points. 148 MCI cases (106 amnestic, 42 non-amnestic (aMCI/naMCI)) and 148 matched controls were identified from a prospective population based cohort study of 4,359 participants (aged 50-80). HsCRP levels were measured 5 years before (baseline) and at the time of neuropsychological testing (follow-up). Odds ratios (OR) for hsCRP quartiles serum levels were calculated for the two time points using logistic regression analyses and were adjusted for cardiovascular covariates. In the fully adjusted model, baseline hsCRP levels were significantly associated with both MCI and aMCI (OR=2.29, 95% confidence interval (CI), 1.01-5.15, first versus fourth quartile, respective OR=2.73, 95%CI, 1.09-6.84). At follow-up, the fourth hsCRP quartile was associated with MCI (OR=3.60, 95%CI, 1.55-8.33), aMCI (OR=3.73, 95%CI, 1.52-9.17) and naMCI (OR=3.66, 95%CI, 1.00-13.77). Elevated hsCRP levels, even detected five years before diagnosis, are associated with an at least twofold increased probability of MCI. These findings suggest that inflammation plays an important role in the development and presence of cognitive impairment.
Supplementary Data for Dlugaj et al. article (PDF)
Seyyed Hani Moussavi Nik, Lachlan Wilson, Morgan Newman, Kevin Croft, Trevor A. Mori, Ian Musgrave, Michael Lardelli
The BACE1-PSEN-AβPP Regulatory Axis has an Ancient Role in Response to Low Oxygen/Oxidative Stress
Abstract: Oxygen homeostasis is essential for the development and normal physiology of an organism. Hypoxia causes the mitochondrial electron transport chain to generate higher levels of reactive oxygen species resulting in oxidative stress. Hypoxia can be a direct consequence of hypoperfusion, a common vascular component among Alzheimer’s disease (AD) risk factors, and may play an important role in AD pathogenesis. Beta-site amyloid-β A4 precursor protein-cleaving enzyme 1 (BACE1) is responsible, with γ-secretase, for cleavage of the amyloid-β protein precursor (AβPP) to produce amyloid-β (Aβ) peptide. A recent study observed that oxidative stress increases BACE1 expression via a regulatory pathway dependent on γ-secretase cleavage of AβPP and this increases Aβ peptide production. Zebrafish embryos represent normal cells in which complex and subtle manipulations of gene activity can be performed to facilitate analysis of genes involved in human disease. Here we identify and describe the expression of bace1, the zebrafish ortholog of human BACE1. We observe that the zebrafish AD-related genes bace1, psen1, psen2, appa, and appb all show increased mRNA levels under hypoxia. A dominant negative form of psen1 putatively blocking γ-secretase activity blocks bace1 upregulation under hypoxia. Hypoxia increases catalase gene mRNA indicating increased oxidative stress but we did not observe increased levels of F2-isoprostanes that indicate peroxidation of arachidonic acid, possibly due to relatively low levels of arachidonic acid in zebrafish. Our results demonstrate that upregulation of PSEN1 & 2, AβPP and the γ-secretase-dependent upregulation of BACE1 is an ancient, conserved, and thus selectively advantageous response to hypoxia/oxidative stress.
Supplementary Data for Moussavi Nik et al. article (PDF)
Gary B. Freeman, John C. Lin, Jaume Pons, Nancy M. Raha
39-Week Toxicity and Toxicokinetic Study of Ponezumab (PF-04360365) in Cynomolgus Monkeys with 12-Week Recovery Period
Abstract: Ponezumab (PF-04360365) is a novel humanized IgG2Δa monoclonal antibody that binds to amyloid-β (Aβ). It is designed to have reduced immune effector function compared to other passive immunotherapies for Alzheimer’s disease (AD). Toxicity was evaluated in cynomolgus monkeys treated intravenously with vehicle or 10, 30, or 100 mg/kg of ponezumab every 10th day for up to 39 weeks, and after a 12-week recovery phase. The Aβ peptide sequence of monkeys is identical to that of humans. No substantial difference in test article exposure between sexes was observed, and mean plasma Cmax and AUC0-n were approximately dose-proportional. Ponezumab was detectable approximately 9 weeks after cessation of dosing. All animals, except two males given 10 mg/kg, maintained exposure to test article. One of these males tested positive for anti-ponezumab antibodies. Ponezumab was detected in the cerebrospinal fluid (CSF) of animals given active treatment. The estimated CSF/plasma ponezumab concentration ratio was <0.008 after multiple doses. At the end of the dosing and recovery phases, plasma Aβ1-40 and Aβ1-x were increased in treated animals versus controls. No test article-related effects were seen after ophthalmogical, cardiovascular, physical examinations, and clinical and anatomic pathology evaluations. Plasma concentrations of ponezumab on day 261 at the no observed adverse effect level of 100 mg/kg were 22.4 and 5.3 times greater on a Cmax and AUC basis, respectively, than human exposures at the highest dose (10 mg/kg) in a single-dose Phase I trial. These data suggest an acceptable safety profile for ponezumab as an immunotherapy for AD.
Panagiotis Alexopoulos, Liang-Hao Guo, Amalia Tsolakidou, Martina Kratzer, Timo Grimmer, Christine Westerteicher, Meizi Jiang, Hideaki Bujo, Janine Diehl-Schmid, Alexander Kurz, Robert Perneczky(Handling Associate Editor: Thomas Leyhe)
Interrelations Between CSF Soluble AβPPβ, Amyloid-β 1-42, SORL1, and Tau Levels in Alzheimer’s Disease
Abstract: Recently, light has been shed on possible interrelations between the two most important pathological hallmarks of Alzheimer’s disease (AD): the amyloid cascade and axonal degeneration. In this study, we investigated associations between sβAPPβ, a product of the cleavage of the amyloid-β protein precursor (AβPP) by β-secretase, amyloid-β 1-42 (Aβ42), soluble SORL1 (also called LR11 or SORLA), a receptor that is involved in AβPP processing, and the marker of axonal degeneration tau in the cerebrospinal fluid (CSF) of 76 patients with mild cognitive impairment (MCI), 61 patients with AD, and 17 patients with frontotemporal dementia, which neuropathologically is not related to the amyloid pathology. In the AD group, significant associations between sAβPPβ, tau (p<0.001), and soluble SORL1 (p<0.001) were detected according to linear regression models. In patients with MCI, sAβPPβ correlated significantly with tau (p<0.001) and soluble SORL1 (p=0.003). In the FTD group, only SORL1 (p=0.011) was associated with sAβPPβ and not tau. Aβ42 was found to be significantly related to tau levels in CSF in the MCI group (p<0.001) and they tended to be associated in the AD group (p=0.05). Our results provide further evidence for a link between the two facets of AD pathology, which is likely to be mediated by the binding of Aβ oligomers to specifically targeted neurons, resulting in stimulating tau hyperphosphorylation and neurodegeneration.
Teemu Natunen, Seppo Helisalmi, Saila Vepsäläinen, Timo Sarajärvi, Leila Antikainen, Petra Mäkinen, Sanna-Kaisa Herukka, Anne Maria Koivisto, Annakaisa Haapasalo, Hilkka Soininen, and Mikko Hiltunen
Genetic Analysis of Genes Involved in Amyloid-β Degradation and Clearance in Alzheimer’s Disease
Abstract: Accumulation of amyloid β-peptide (Aβ) in the brain of Alzheimer's disease (AD) patients has been postulated to reflect defects in Aβ degradation or clearance. Here, we selected 12 genes (MMEL1, ECE1, ECE2, AGER, PLG, PLAT, NR1H3, MMP3, LRP1, TTR, NR1H2, and MMP9) involved in Aβ catabolism on the basis of PubMed-based literature search and elucidated their genetic role in AD among Finnish case-control cohort consisting of total ~1,300 AD patients and control subjects. Thirty one single nucleotide polymorphisms (SNPs) were selected for genotyping. In a smaller subset of AD patients, cerebrospinal fluid (CSF) levels of Aβ42 (n=124), total-tau (n=59), and phospho-tau (n=54) analyses were performed with respect to SNPs. Moreover, age of onset analyses with respect to the studied SNPs were conducted among the AD patient cohort (n=642). Association analysis of the liver X receptor α (NR1H3) gene SNPs showed a protective effect for C allele carriers of rs7120118 (OR=0.70, 95% CI 0.53-0.93), while the total-tau and phospho-tau levels in CSF were decreased in AD patients carrying the C allele. Also, a decrease in the age of onset was observed in AD patients carrying the A allele of rs723744 and the C allele of rs3794884 in transthyretin (TTR) gene. However, after adjusting the p-values for multiple comparisons, these results were not statistically significant, suggesting that genetic variations in MMEL1, ECE1, ECE2, AGER, PLG, PLAT, NR1H3, MMP3, LRP1, TTR, NR1H2, and MMP9 genes do not play major role among the Finnish AD patient cohort.
Cyril Pottier, David Wallon, Anne Rovelet Lecrux, David Maltete, Stephanie Bombois, Snejana Jurici, Thierry Frebourg, Didier Hannequin, Dominique Campion
Amyloid-β Protein Precursor Gene Expression in Alzheimer’s Disease and Other Conditions
Abstract: Several lines of evidence suggest that AβPP gene expression could influence risk for Alzheimer’s disease (AD). Using a highly sensitive multiplex fluorescent RT-PCR assay, we compared peripheral blood cells expression of AβPP mRNA among sporadic AD patients (n=133), autosomal dominant early-onset AD cases (ADEOAD, n=21), Down syndrome patients (n=21), AD patients with AβPP duplication (n=9), patients with recent ischemic stroke (n=25), and healthy controls (n=58). Compared to healthy controls (median=0.98), AβPP expression was not increased in sporadic AD patients (median=1.01, p=0.42) nor in ADEOAD patients (median=0.96, p=0.26). Down syndrome patients as well as patients with AβPP duplication had significantly increased levels of AβPP mRNA compared to controls (median=1.48 and median=1.36, p<0.0001 and p=0.0007, respectively). A weaker but significant increase in relative amount of AβPP transcripts in patients who suffered from recent stroke was observed (median=1.14, p=0.0007). Our results do not support a pathogenic role of AβPP overexpression in sporadic AD although a small subset of patients displays AβPP overexpression in the same range as Down syndrome patients.
Mar Cuadrado-Tejedor, Ana Ricobaraza, Diana Frechilla, Rafael Franco, Alberto Pérez-Mediavilla*, Ana Garcia-Osta Ana* (Handling Associate Editor: Garth Bissette) *Both authors contributed equally to this work.
Chronic Mild Stress Accelerates the Onset and Progression of the Alzheimer’s Disease Phenotype in Tg2576 Mice
Abstract: The etiology of the more common (sporadic) forms of Alzheimer’s disease (AD) remains unknown, although age is the most important risk factor. Nevertheless, interactions between environmental risk factors and genetic background may also influence the onset and progression of sporadic AD. Chronic stress, associated with altered memory and other neurological processes, is thought to influence the pathogenesis of AD. Hence, we evaluated the effect of unpredictable and consecutive chronic mild stressors on the onset of an AD-related pathology in the Tg2576 mouse line that overexpresses the human amyloid-β protein precursor with the Swedish mutation (hAβPPSwe). Two months after exposure to chronic mild stress, 4 month-old animals that normally display no pathological features of AD, not only expressed pathological markers but also experienced cognitive dysfunction in the Morris water maze test. These findings suggest that chronic mild stress accelerates the onset of cognitive impairment and produces an increase in hippocampal amyloid-β and phospho-tau levels on a background of AD susceptibility.
Supplementary Data for Cuadrado-Tejedor et al. article (PDF)
Hongxin Dong, Keely M. Murphy, Liping Meng, Janitza Montalvo-Ortiz, Ziling Zeng, Benedict J. Kolber, Shanshan Zhang, Louis J. Muglia, John G. Csernansky
Corticotrophin Releasing Factor Accelerates Neuropathology and Cognitive Decline in a Mouse Model of Alzheimer’s Disease
Abstract: Chronic stress has been suggested to influence the pathogenesis of Alzheimer’s disease (AD); however, the mechanism underlying this influence remains unknown. In this study, we created a triple transgenic mouse model that overexpresses corticotrophin-releasing factor (CRF) and human amyloid-β protein precursor (AβPP), to investigate whether increases in the expression of CRF can mimic the effects of stress on amyloid metabolism and the neurodegeneration. Tg2576 mice that overexpresses human AβPP gene were crossbreed with Tetop-CRF (CRF) mice and CaMKII-tTA (tTA) mice to create a novel triple transgenic mouse model that conditioned overexpresses CRF in forebrain and overexpresses human AβPP (called AβPP +/CRF+/tTA+, or TT mice). Then we evaluated serial neuro-anatomical and behavioral phenotypes on TT mice using histological, biochemical, and behavioral assays. TT mice showed a Cushingoid-like phenotype starting at 3 months of age. At 6 months of age, these mice demonstrated increases in tissue-soluble amyloid-β (Aβ) and Aβ plaques in the cortex and hippocampus, as compared to control mice. Moreover, TT mice characterized substantial decreases in dendritic branching and dendritic spine density in pyramidal neurons in layer 4 of the frontal cortex and CA1 of the hippocampus. Finally, TT mice showed significantly impaired working memory and contextual memory, with a modest increase in anxiety-like behavior. Our results suggested genetic increases in the brain of CRF expression mimicked chronic stress on the effects of amyloid deposition, neurodegeneration, and behavioral deficits. The novel transgenic mouse model will provide a unique tool to further investigate the mechanisms between stress and AD.
Takehiro Kiko, Kiyotaka Nakagawa, Tsuyoshi Tsuduki, Hiroyuki Arai, Teruo Miyazawa
Significance of Lutein in Red Blood Cells of Alzheimer's Disease Patients
Abstract: Red blood cells (RBC) of Alzheimer's disease (AD) patients are known to be in an excessively oxidized state (i.e., with a high accumulation of peroxidized phospholipids (PLOOH)). Previously we confirmed in vitro, in vivo murine, and in human studies that carotenoids can effectively inhibit accumulation of RBC PLOOH. Thus, the relationship between RBC carotenoids and PLOOH concentrations in AD patients is of interest. In this study, RBC carotenoids and PLOOH were evaluated in 28 normal control subjects (age: 74.1 ± 1.3 years) and 28 patients with AD (age: 72.5 ± 1.4 years). The concentrations of RBC carotenoids, especially lutein, in AD patients were significantly lower than in control subjects. An inverse relationship was seen between RBC carotenoids, especially lutein, and PLOOH concentrations in AD patients. These results suggest that RBC lutein, in particular, may contribute to suppression of PLOOH accumulation in RBC of AD patients.
Constance Chace, Deborah Pang, Catherine Weng, Alexis Temkin, Simon Lax , Wayne Silverman, Warren Zigman, Michel Ferin, Joseph H. Lee, Benjamin Tycko, Nicole Schupf
Variants in CYP17 and CYP19 Cytochrome P450 Genes are Associated with Onset of Alzheimer’s Disease in Women with Down Syndrome
Abstract: CYP17 and CYP19 are involved in the peripheral synthesis of estrogens, and polymorphisms in CYP17 and CYP19 have been associated with increased risk of estrogen-related disorders. Women with Down syndrome (DS) have early onset and high risk for Alzheimer’s disease (AD). We conducted a prospective community-based cohort study to examine the relationship between SNPs in CYP17 and CYP19 and cumulative incidence of AD, hormone levels and sex hormone binding globulin in women with DS. Two hundred and thirty-five women with DS, 31 to 67 years of age and nondemented at initial examination, were assessed for cognitive and functional abilities, behavioral/psychiatric conditions, and health status at 14-20 month intervals over five assessment cycles. We genotyped these individuals for single-nucleotide polymorphisms (SNPs) in CYP17 and CYP19. Four SNPs in CYP17 were associated with a two and one half-fold increased risk of AD, independent of APOE genotype. Four SNPs in CYP19 were associated with a two-fold increased risk of AD, although three were significant only in those without an APOE ε4 allele. Further, carrying high risk alleles in both CYP17 and CYP19 was associated with an almost four-fold increased risk of AD (OR=3.8, 95% CI, 1.6-9.5) and elevated sex hormone binding globulin in postmenopausal women. The main effect of the CYP17 and CYP19 variants was to decrease the age at onset. These findings suggest that genes contributing to estrogen bioavailability influence risk of AD in women with DS.
Angela R. Kamer, Douglas E. Morse, Poul Holm-Pedersen, Erik L Mortensen, Kirsten Avlund
Periodontal Inflammation in Relation to Cognitive Function in an Older Adult Danish Population
Abstract: Inflammation plays a significant role in Alzheimer’s disease (AD) pathogenesis. Studies have shown that systemic, peripheral infections affect AD patients. Cognitive dysfunction is a consistent finding in AD and periodontal disease is a chronic, peripheral infection often resulting in tooth loss. We hypothesized that older adults with periodontal inflammation (PI) or many missing teeth would show impaired cognition compared to subjects without PI or with few missing teeth, and among subjects with PI, those with many missing teeth would show impaired cognition compared to those with few missing teeth. The effect of PI/tooth loss on cognitive function [measured by Digit Symbol (DST) and Block Design (BDT) tests] was assessed in 70-year old Danish subjects. We found: 1) subjects with PI obtained lower mean DST scores compared to subjects without PI (p<0.05); 2) subjects with many missing teeth had lower mean DST and BDT scores compared to subjects with few missing teeth (p<0.05); 3) the association of PI with DST and BDT scores was dependant on the number of missing teeth (interaction: p=0.03 and p=0.06); and 4) education and previous cognitive scores (age 50) were important covariates. Subjects with PI had significantly lower adjusted mean DST scores compared to subjects without PI. However for adjusted BDT, the significance held only for subjects with few missing teeth. No difference in the adjusted DST and BDT scores was seen between subjects with many missing teeth compared to those with few missing teeth. These results support the hypothesis that PI may affect cognition.
Baharak Vafadar-Isfahani, Graham Ball, Clare Coveney, Christophe Lemetre, David Boocock, Lennart Minthon, Oskar Hansson, Amanda Kathleen Miles, Sabina M Janciauskiene, Donald Warden, A. David Smith, Gordon Wilcock, Noor Kalsheker, Robert Rees, Balwir Matharoo-Ball, Kevin Morgan *These authors contributed equally to this work.
Identification of SPARC-Like Protein as Part of a Biomarker Panel for Alzheimer’s Disease in Cerebrospinal Fluid
Abstract: We have used proteomic fingerprinting to investigate diagnosis of Alzheimer’s disease (AD). Samples of lumbar cerebrospinal fluid (CSF) from clinically-diagnosed AD cases (n = 33), age-matched controls (n = 20), and mild cognitive impairment (MCI) patients (n=10) were used to obtain proteomic profiles, followed by bioinformatic analysis that generated a set of potential biomarkers in CSF samples that could discriminate AD cases from controls. The identity of the biomarker ions was determined using mass spectroscopy. The panel of seven peptide biomarker ions was able to discriminate AD patients from controls with a median accuracy of 95% (sensitivity 85%, specificity 97%). When this model was applied to an independent blind dataset from MCI patients, the intensity of signals was intermediate between the control and AD patients implying that these markers could potentially predict patients with early neurodegenerative disease. The panel were identified, in order of predictive ability, as SPARC-like 1 protein, fibrinogen alpha chain precursor, amyloid-β, apolipoprotein E precursor, serum albumin precursor, keratin type I cytoskeletal 9, and tetranectin. The 7 ion ANN model was further validated using an independent cohort of samples, where the model was able to classify AD cases from controls with median accuracy of 84.5% (sensitivity 93.3%, specificity 75.7%). Validation by immunoassay was performed on the top three identified markers using the discovery samples and an independent sample cohort which was from postmortem confirmed AD patients (n = 17).
Huifen Wang, Andrew Odegaard, Bharat Thyagarajan, Jennifer Hayes, Karen Santa Cruz, Mark F. Derosiers, Suzanne Tyas, Myron D. Gross
Blood Folate is Associated with Asymptomatic or Partially Symptomatic Alzheimer’s Disease in the Nun Study
Abstract: Asymptomatic and partially symptomatic Alzheimer’s disease (APSYMAD) are a series of cognitive states wherein subjects have substantial Alzheimer’s disease (AD) pathology (classification B or C by the Consortium to Establish a Registry for AD criteria), but have normal or only partially impaired cognitive function; all of these subjects are non-demented. These cognitive states may arise from the prevention or delay of clinical symptom expression by exposure to certain nutritional factors. This study examined blood levels of folate and antioxidants (i.e., carotenoids) in relation to APSYMAD, nested in the Nun study, a longitudinal study of aging and AD. Sixty elderly female subjects, who had AD on the basis of neuropathology exams, were included. Following adjustment for APOE4 status, education level, and age at blood draw, subjects with the highest blood folate levels had a higher likelihood of being in the APSYMAD group as compared to the demented (AD) group (odds ratio=1.09, 95% CI=1.00-1.18. p<0.06). This association was not significantly influenced by additional adjustment for blood concentrations of carotenoids. Restriction of the population to subjects with near normal cognition on the cognitive state score (score=1-3) indicated an elevated association with blood folate (odds ratio=1.12, 95% CI=1.01-1.25, p<0.04). Blood carotenoids were not associated with APSYMAD. Thus, folate status may influence the expression of clinical symptoms of AD disease and aid in the delay or prevention of dementia.
Maria E Soto, Marion Secher, Sophie Gillette-Guyonnet, Gabor Abellan van Kan, Sandrine Andrieu, Fati Nourhashemi, Yves Rolland, Bruno Vellas (Handling Associate Editor: Martha Clare Morris)
Weight Loss and Rapid Cognitive Decline in Community-Dwelling Patients with Alzheimer’s Disease
Abstract: Weight loss is a frequent complication of Alzheimer’s disease (AD) and a strong predictor of adverse outcomes in patients suffering from this disease. The aim of this study was to determine whether weight loss was a predictor of rapid cognitive decline (RCD) in AD. Four hundred fourteen community-dwelling ambulatory patients with a diagnosis of probable AD and a Mini-Mental State Examination (MMSE) score between 10 and 26 from the REAL.FR (REseau sur la maladie d’ALzheimer FRançais) cohort were studied and followed up during 4 years. Patients were classified in 2 groups according to weight loss defined by a loss of 4% or more during the first year of follow-up. RCD was defined as the loss of 3 points or more in MMSE over 6 months. The incidence of RCD was determined among both groups over the last 3 years of follow-up. MMSE, Katz’s Activity of Daily Living scale, Mini-Nutritional Assessment scale, co-morbidities, behavioral and psychological symptoms of dementia, medication, level of education, living arrangement, and caregiver’s burden were assessed every 6 months. Eighty-seven patients (21.0%) lost 4% or more of their initial weight during the first year. The incidence of RCD for all patients was 57.6 (95% confidence interval (CI) =51.6-64.8) per 100 person-year (median follow-up of 15.1 months). In Cox proportional hazards models, after controlling for potential confounders, weight loss was a significant predictor factor of RCD (adjusted hazard ratio (HR) =1.50, 95%CI =1.04-2.17). In conclusion, weight loss predicted RCD in this cohort. Whether the prevention of weight loss (by improving nutritional status) impacts cognitive decline remains an open question.
Cheng Zhang, Cynthia Rodriguez, James Spaulding, Tak Yee Aw, June Feng (Handling Associate Editor: Xuemin Xu)
Age-Dependent and Tissue-Related Glutathione Redox Status in a Mouse Model of Alzheimer’s Disease
Abstract: Glutathione plays an essential role in the intracellular antioxidant defense against oxidant radicals, especially the •OH radical. To understand the early and progressive cellular changes in the development of Alzheimer’s disease (AD), we investigated reduced glutathione/oxidized glutathione (GSH/GSSG) status in a double mutated AD transgenic mouse model (B6.Cg-Tg), which carries Swedish amyloid-β protein precursor mutation (AβPPswe) and exon 9 deletion of the PSEN1 gene. In this study, we quantified and compared both GSH/GSSG and mixed-disulfide (Pr-SSG) levels in blood samples and three anatomic positions in brain (cerebrum, cerebellum, and hippocampus) at 3 age stages (1, 5, and 11 months) of AD transgenic (Tg)/wild type mice. The present study was designed to characterize and provide insight into the glutathione redox state of both brain tissues and blood samples at different disease stages of this Tg model. The level of Pr-SSG increased in all AD brain tissues and blood compared with controls regardless of age. The GSH/GSSG ratio in AD-Tg brain tissue started at a higher value at 1 month, fell at the transitional period of 5 months, right before the onset of amyloid plaques, followed by an increase in GSSG and associated decrease of GSH/GSSG at 11 months. These results suggest that formation of Pr-SSG may be an early event, preceding amyloid plaque appearance, and the data further implies that tissue thiol redox is tightly regulated. Notably, the high basal levels of mixed-disulfides in hippocampus suggest a potential for increased oxidative damage under oxidizing conditions and increased GSSG in this vulnerable region.
Zehavit Kariv-Inbal*, Shiri Yacobson*, Robert Berkecz, Maria Peter, Tamas Janaky, Dieter Lütjohann, Laus M. Broersen, Tobias Hartmann, Daniel M. Michaelson (Handling Associate Editor: Hilkka Soininen) *The first two authors contributed equally to the manuscript.
The Isoform-Specific Pathological Effects of ApoE4 in vivo are Prevented by a Fish Oil (DHA) Diet and are Modified by Cholesterol
Abstract: Apolipoprotein E4 (apoE4) is the most prevalent genetic risk factor for Alzheimer’s disease (AD). Epidemiological studies revealed that consumption of docosahexaenoic acid (DHA: 22:6 (ω3)), a major brain polyunsaturated fatty acid, is protective for AD and that elevated cholesterol levels are an AD risk factor. We presently investigated the extent to which the pathological effects of apoE4 in vivo can be prevented by consuming fish oil (DHA) or can be modified by cholesterol. Accordingly, apoE3- and apoE4-targeted replacement mice were subjected, following weaning, to a fish oil diet enriched in DHA and to a cholesterol-containing diet under regular and enriched environments. Cholesterol metabolism in the hippocampus and the corresponding phospholipid and fatty acid levels were affected by fish oil (DHA) and cholesterol diets and by environmental stimulation. Importantly, cholesterol metabolism and the fatty acid levels were not affected by apoE4. The phospholipid levels were, however, affected by apoE4. This effect was most pronounced in the cholesterol-fed mice and was abolished by the fish oil (DHA) diet. ApoE4 elevated hippocampal intraneuronal amyloid-β levels under regular conditions and lowered them following environmental stimulation, relative to those of the apoE3 mice. ApoE4 also elevated the levels of the presynaptic transporters Vglut and Vgat, and decreased behavioral performance in an object recognition test. Importantly, all of these apoE4 phenotypes were abolished by the fish oil (DHA) diet, whereas the cholesterol diet modified them. These findings suggest that a fish oil (DHA) diet could be used to attenuate the effects of apoE4 in AD.
Supplementary Data for Kariv-Inbal et al. article (PDF)
Maria B. Fonseca, Ana F. Nunes, Cecília M. P. Rodrigues
c-Jun Regulates the Stability of Anti-Apoptotic ΔNp63 in Amyloid-β-induced Apoptosis
Abstract: p63, the structural and functional homologue of p53, is expressed either as a full-length isoform, containing a transactivation (TA) domain (TAp63), or as a truncated isoform, which lacks TA (ΔNp63). Amyloid-β (Aβ) incubation of neuronal cells results in stress-induced cell death through poorly understood mechanisms. We investigated the role of p63 in Aβ-induced stress. Our results show that Aβ-induced apoptosis of rat PC12 neuronal-like cells and primary cortical neurons was associated with stabilization of pro-apoptotic TAp63 and, most importantly, degradation of anti-apoptotic ΔNp63 through a MAPK- and proteasome-dependent mechanism. This was associated with increased c-Jun, and partially modulated by tauroursodeoxycholic acid. As expected, classic genotoxic insults resulted in c-Jun upregulation and concomitant ΔNp63 reduction. Endogenous and ectopic ΔNp63 expression was also markedly reduced by c-Jun overexpression. Further, Aβ-mediated ΔNp63 degradation occurred in a c-Jun-dependent manner. Downregulation of c-Jun expression by specific c-Jun siRNA abrogated the reduction of ΔNp63 levels following Aβ insult, whereas overexpression of c-Jun led to its degradation. c-Jun significantly decreased ΔNp63 half-life. Together, these findings demonstrate that the abundance of anti-apoptotic ΔNp63 in response to Aβ-induced cell stress is regulated by a c-Jun-dependent mechanism, and highlight the importance of finding novel targets for potential therapeutic intervention.
Takao Yamasaki, Yoshinobu Goto, Yasumasa Ohyagi, Akira Monji, Shinji Munetsuna, Motozumi Minohara, Katsuko Minohara, Jun-ichi Kira, Shigenobu Kanba, Shozo Tobimatsu (Handling Associate Editor: Jinglong Wu)
Selective Impairment of Optic Flow Perception in Amnestic Mild Cognitive Impairment: Evidence From Event-Related Potentials
Abstract: Alzheimer’s disease (AD) patients have visuospatial deficits due to parietal dorsal stream dysfunction. Two distinct dorsal flows have been proposed: the inferior parietal (ventro-dorsal (v-d)) and superior parietal (dorso-dorsal (d-d)) streams. We aimed to elucidate how the two dorsal streams are altered in patients with amnestic mild cognitive impairment (aMCI) and AD. Thus, the psychophysical threshold measurements and visual event-related potentials (ERPs) were recorded in patients with aMCI and AD, and in healthy old and young adults. The visual stimuli included radial optic flow (OF) derived from the v-d stream and horizontal (HO) motion conveyed from the d-d stream. The motion thresholds between aMCI patients and old adults were comparable. However, AD patients showed significantly higher motion thresholds for both stimuli compared with other groups. In lower-level ERPs, there were no significant differences in P1 (100 ms) and N1 (130 ms) for both stimuli among the groups. For higher-level ERPs, aMCI patients showed the prolonged latency of OF-specific P200 (v-d origin) and comparable latency of motion-related N170 (V5/MT origin) for both stimuli compared with old adults. In AD patients, both N170 and P200 latencies were significantly prolonged compared with other groups. P200 latency was closely correlated with the Mini-Mental State Examination score. These findings indicate that the v-d function related to OF perception is selectively impaired in aMCI, whereas AD has impairment of the distributed higher-level dorsal stream. Therefore, OF-specific P200 can be useful for detecting early functional changes of the brain in aMCI.
Takahiro Sugihara, Seiichi Munesue, Yasuhiko Yamamoto, Shigeru Sakurai, Nasima Akhter, Yoji Kitamura, Kazuhiro Shiba, Takuo Watanabe, Hideto Yonekura, Yasuhiko Hayashi, Jun-ichiro Hamada, Hiroshi Yamamoto (Handling Associate Editor: Masahito Yamada)
Endogenous Secretory Receptor for Advanced Glycation End-Products Inhibits Amyloid-β1-42 Uptake into Mouse Brain
Abstract: The cell-surface receptor for advanced glycation end-products (RAGE) has been implicated in the development of diabetic vascular complications and Alzheimer's disease. RAGE has been considered to be involved in amyloid-β1-42 (Aβ1-42) uptake into brain. In the present study, we demonstrate that endogenous secretory RAGE (esRAGE), a decoy form of RAGE generated by alternative RNA processing, is able to inhibit Aβ1-42 influx into mouse brain. Surface plasmon resonance and competitive binding assays revealed that human Aβ1-42 interacted with human esRAGE within the immunoglobulin V type region. We next examined the uptake and distribution of 125I-labeled human Aβ1-42 in various organs and body fluids of newly created mice overexpressing human esRAGE as well as RAGE-null and wild-type (WT) mice. The transition of the 125I-labeled Aβ1-42 from circulation to brain parenchyma peaked at 30 min after the injection into WT mice, but this was significantly blunted in esRAGE-overexpressing and RAGE-null mice. Brain regions where significant reduction in 125I-labeled Aβ1-42-derived photo-stimulated luminescence were marked in ventricles, cerebral cortex, hippocampus, especially CA1 and CA3 regions, putamen, and thalamus. The results thus suggest the potential of esRAGE in protection against the development of Alzheimer's disease.
Sophie Gillette-Guyonnet, Bruno Vellas
The Toulouse Gérontopôle Research Center: Report of Activities, 2007-2009
Abstract: The formation of the first Gerontopole in Toulouse was a response to a mission letter sent by French Ministers of Health on February 2007. The mission of the Toulouse Gerontopole is based around three major axes:1) To facilitate the access of frail elderly people to innovative therapy and clinical research: the Gérontopôle set up the national network for clinical investigation into Alzheimer’s disease (AD) funded through the CeNGEPS (National Centre For Management of Trials on Health Products) calls for proposals since July 2008. In addition, the Gérontopôle coordinates several national clinical trials with promising drugs with potential effect on the mechanisms and evolution of AD and actively participates in studies on biomarkers; 2) To develop health promotion actions and prevention trials for healthy elderly people, through the Institute of Aging: the Gérontopôle has implemented the GuidAge (Phase III trial concerning the efficiency of Ginkgo Biloba on the impact and delay of appearance of an Alzheimer type dementia) and MAPT (Multi-domain Alzheimer Preventive Trial) studies on prevention of AD and cognitive decline. It is curently working on the new generation of preventive trials based on biomarkers; 3) To develop clinical research for dependant elderly people, through the implementation of the REHPA research network including 240 nursing homes in France. In December 2009, additional grants were delivered by the French government to extend the three research axes for two more years, and establish a charter of quality for geriatric care in relation with the administration and relevant agencies.