Systemic immune challenges trigger and drive Alzheimer-like neuropathology in mice.

J Neuroinflammation. 2012 Jul 2;9:151.

Dimitrije Krstic, Amrita Madhusudan, Jana Doehner, Prisca Vogel, Tina Notter, Claudine Imhof, Abigail Manalastas, Martina Hilfiker, Sandra Pfister, Cornelia Schwerdel, Carsten Riether, Urs Meyer and Irene Knuesel.

Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.

 

Abstract

BACKGROUND: Alzheimer’s disease (AD) is the most prevalent form of age-related dementia, and its effect on society increases exponentially as the population ages. Accumulating evidence suggests that neuroinflammation, mediated by the brain’s innate immune system, contributes to AD neuropathology and exacerbates the course of the disease. However, there is no experimental evidence for a causal link between systemic inflammation or neuroinflammation and the onset of the disease.

METHODS: The viral mimic, polyriboinosinic-polyribocytidilic acid (PolyI:C) was used to stimulate the immune system of experimental animals. Wild-type (WT) and transgenic mice were exposed to this cytokine inducer prenatally (gestation day (GD)17) and/or in adulthood. Behavioral, immunological, immunohistochemical, and biochemical analyses of AD-associated neuropathologic changes were performed during aging.

RESULTS: We found that a systemic immune challenge during late gestation predisposes WT mice to develop AD-like neuropathology during the course of aging. They display chronic elevation of inflammatory cytokines, an increase in the levels of hippocampal amyloid precursor protein (APP) and its proteolytic fragments, altered Tau phosphorylation, and mis-sorting to somatodendritic compartments, and significant impairments in working memory in old age. If this prenatal infection is followed by a second immune challenge in adulthood, the phenotype is strongly exacerbated, and mimics AD-like neuropathologic changes. These include deposition of APP and its proteolytic fragments, along with Tau aggregation, microglia activation and reactive gliosis. Whereas Aβ peptides were not significantly enriched in extracellular deposits of double immune-challenged WT mice at 15 months, they dramatically increased in age-matched immune-challenged transgenic AD mice, precisely around the inflammation-induced accumulations of APP and its proteolytic fragments, in striking similarity to the post-mortem findings in human patients with AD.

CONCLUSION: Chronic inflammatory conditions induce age-associated development of an AD-like phenotype in WT mice, including the induction of APP accumulations, which represent a seed for deposition of aggregation-prone peptides. The PolyI:C mouse model therefore provides a unique tool to investigate the molecular mechanisms underlying the earliest pathophysiological changes preceding fibrillary Aβ plaque deposition and neurofibrillary tangle formations in a physiological context of aging. Based on the similarity between the changes in immune-challenged mice and the development of AD in humans, we suggest that systemic infections represent a major risk factor for the development of AD.

PMID: 22747753

 

Supplement picture:

Irene Knuesel NRNEURO_Fig1_adapted

 

 

Press release:

Inflammation in the brain leads the way to Alzheimer’s Disease

Research published in Biomed Central’s open access journal Journal of Neuroinflammation suggests that sustained inflammation represents a major risk factor to develop Alzheimer’s disease.

To date it has been difficult to pin down the role of inflammation in Alzheimer’s disease (AD), especially because trials of NSAIDs appeared to have conflicting results. Although the ADAPT (The Alzheimer`s Disease Anti-inflammatory Prevention Trial) was stopped early, recent results suggest that NSAIDs can help people with early stages of AD but that prolonged treatment is necessary to see benefit.

Researchers from the University of Zurich, collaborating with groups at the ETH Zürich and University of Bern, investigated what would be the impact of chronic inflammation, induced by a viral-like infection, on the development of AD in mice. Results showed that in wild-type (genetically nonmodified) mice a single infection before birth (during late gestation) induced long-term changes in AD relevant pathways and significant memory problems at old age.

These mice had increased levels of inflammatory messengers (cytokines), paralleled by a rise in amyloid precursor protein (APP) and its fragments, as well as altered modification and cellular localization of Tau. If this immune system challenge was repeated during aging the effect was exacerbated and resulted in plaque-like aggregation of APP and its fragments; importantly, in the same brain areas that are affected during early stages of AD.

Dr Irene Knuesel who led this research explained, “The AD-like changes within the brains of these wild-type mice occurred without an increase in amyloid β peptides (Aβ). However in mice genetically modified to produce the human version of this aggregation-prone peptide, the viral-like challenge drastically increased Aβ depositions at precisely the sites of inflammation-induced APP depositions. Based on the similarity between these APP/Aβ aggregates and those found in human AD patients, it seems that chronic inflammation due to infection or a disease could be an early triggering event in the development of AD, potentially preceding the formation of typical AD hallmarks for years”. 

http://biomedfrontiers.org/alzheimer-2013-jun-2/

Diabetes. 2013 Jan;62(1):194-204.

Upregulated NLRP3 inflammasome activation in patients with type 2 diabetes.

Lee HM, Kim JJ, Kim HJ, Shong M, Ku BJ, Jo EK.

Infection Signaling Network Research Center, Chungnam National University School of Medicine, Daejeon, South Korea.

Abstract

Despite the recent attention focused on the roles of the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in the pathogenesis of type 2 diabetes, little is known about the ex vivo profile of inflammasome activation in type 2 diabetic patients. In this study, we investigated patterns of NLRP3 inflammasome activation in monocyte-derived macrophages (MDMs) from drug-naïve patients with newly diagnosed type 2 diabetes. Type 2 diabetic subjects had significantly increased mRNA and protein expression of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and proinflammatory cytokines in MDMs cultured with autologous sera compared with healthy controls. Upregulated interleukin (IL)-1β maturation, IL-18 secretion, and caspase-1 cleavage were observed in MDMs from type 2 diabetic patients after stimulation with various danger molecules (ATP, high-mobility group protein B1, free fatty acids, islet amyloid polypeptide, and monosodium uric acid crystals). Mitochondrial reactive oxygen species and NLRP3 were required for IL-1β synthesis in MDMs. Finally, 2 months of therapy with the antidiabetic drug metformin significantly inhibited the maturation of IL-1β in MDMs from patients with type 2 diabetes through AMP-activated protein kinase (AMPK) activation. Taken together, these data suggest that NLRP3 inflammasome activation is elevated in myeloid cells from type 2 diabetic patients and that antidiabetic treatment with metformin contributes to modulation of inflammasome activation in type 2 diabetes.

PMID: 23086037

http://biomedfrontiers.org/diabetes-2013-may-2-19/

PLoS One. 2013;8(3):e58243.

Altered ureteric branching morphogenesis and nephron endowment in offspring of diabetic and insulin-treated pregnancy.

Hokke SN, Armitage JA, Puelles VG, Short KM, Jones L, Smyth IM, Bertram JF, Cullen-McEwen LA.

Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia.


Abstract

There is strong evidence from human and animal models that exposure to maternal hyperglycemia during in utero development can detrimentally affect fetal kidney development. Notwithstanding this knowledge, the precise effects of diabetic pregnancy on the key processes of kidney development are unclear due to a paucity of studies and limitations in previously used methodologies. The purpose of the present study was to elucidate the effects of hyperglycemia on ureteric branching morphogenesis and nephrogenesis using unbiased techniques. Diabetes was induced in pregnant C57Bl/6J mice using multiple doses of streptozotocin (STZ) on embryonic days (E) 6.5-8.5. Branching morphogenesis was quantified ex vivo using Optical Projection Tomography, and nephrons were counted using unbiased stereology. Maternal hyperglycemia was recognised from E12.5. At E14.5, offspring of diabetic mice demonstrated fetal growth restriction and a marked deficit in ureteric tip number (control 283.7 ± 23.3 vs. STZ 153.2 ± 24.6, mean ± SEM, p<0.01) and ureteric tree length (control 33.1 ± 2.6 mm vs. STZ 17.6 ± 2.7 mm, p = 0.001) vs. controls. At E18.5, fetal growth restriction was still present in offspring of STZ dams and a deficit in nephron endowment was observed (control 1246.2 ± 64.9 vs. STZ 822.4 ± 74.0, p<0.001). Kidney malformations in the form of duplex ureter and hydroureter were a common observation (26%) in embryos of diabetic pregnancy compared with controls (0%). Maternal insulin treatment from E13.5 normalised maternal glycaemia but did not normalise fetal weight nor prevent the nephron deficit. The detrimental effect of hyperglycemia on ureteric branching morphogenesis and, in turn, nephron endowment in the growth-restricted fetus highlights the importance of glycemic control in early gestation and during the initial stages of renal development.

PMID: 23516451

 

Luise McEwen

 

Supplementary Figure: A) Duplex collecting duct system at embryonic day 14.5, kidney stained for the ureteric tree and imaged with optical projection tomography. B) Kidney with duplex ureter and hydroureter at embryonic day 18.5 (left) and control kidney (right). C) Histological section of kidney with duplex ureter and hydroureter.

It is well established that a range of perturbations to the feto-maternal environment can increase the risk of chronic disease (such as hypertension, chronic kidney disease (CKD), obesity or type 2 diabetes) in adulthood, a phenomenon known as developmental programming or “developmental origins of health and disease.” The kidney appears to be particularly susceptible to the effects of developmental programming with both genetic and environmental factors contributing to the programming of subsequent risk of CKD.

Both human and animal studies have demonstrated a link between a reduction in the number of nephrons and later renal dysfunction. Nephrogenesis involves reciprocal molecular signalling/interactions between an epithelial ureteric bud and a mass of surrounding mesenchyme (metanephric mesenchyme). The mesenchyme induces the bud to branch into a complex tree-like structure, which ultimately forms the renal collecting duct system. Nephrons are induced only at the tips of the branching ureteric epithelium. The tip induces the mesenchyme directly surrounding the tip (cap mesenchyme) to epithelialize and differentiate. Nephrogenesis is a complex process highly regulated by the extent of branching morphogenesis (number of ureteric tips available for nephron induction). In addition, cells of the metanephric mesenchyme within which the arborisation occurs must be able to commit and differentiate into nephrons as well as maintain a self-renewing pool of undifferentiated cells to enable further induction. Nephrogenesis ceases when this self-renewing pool of progenitor cells is lost.

Previous studies have identified that development of the fetal kidney is susceptible to maternal hyperglycemia and results in a low nephron number. Our paper examines how maternal hyperglycemia affects both nephrogenesis and branching morphogenesis in a mouse model of maternal diabetes and whether treatment with insulin mid to late gestation to restore normoglycemia can prevent the nephron deficit. Our results confirm a nephron deficit with exposure to maternal diabetes and this is associated with reduced ureteric tree development. Interestingly, maternal diabetes was also associated with 25% of offspring showing congenital renal abnormalities such as duplex collecting duct systems and hydroureter (see supplementary Figure), highlighting the susceptibility of the developing kidney to excess glucose levels during development. Our results also indicate that glucose should be tightly controlled during early stages of kidney development to prevent a nephron deficit in the offspring.

 

http://biomedfrontiers.org/diabetes-2013-may-2-18/

Eur J Epidemiol. 2016 Mar;31(3):217-28. doi: 10.1007/s10654-016-0135-9.

The design of empirical studies: towards a unified view.

Cox DR1.

Nuffield College, Oxford, OX1 1NF, UK. david.cox@nuffield.ox.ac.uk.

 

Abstract

A broad review is given of the general principles underlying study design with emphasis on applications in medical and epidemiological contexts. The main theme of the paper is that, while the distinction between interventionist studies, that is experiments, and purely observational ones is important, there are many common threads. A wide range of specific applications are used in outline to illustrate the discussion.

KEYWORDS:

Bias; Case–control study; Clinical trial; Cohort study; Confounding; Generalizability; Longitudinal study; Metrology; Objectives of study; Prospective study; Randomization; Retrospective study; Specificity

PMID: 26968840; DOI:10.1007/s10654-016-0135-9

 

Supplement:

THE DESIGN OF STUDIES

The most common role of statistical considerations in biomedical contexts is in the analysis and interpretation of data whenever that data are subject to  appreciable unexplained or uncontrollable variation. That role in turn takes two broad forms.

The first concerns the security of conclusions. Suppose that there seems to be a systematic difference between the survival times of two groups of patients. Could that difference reasonably be regarded as a consequence of the “play of chance” or is it in some sense real, that is likely to be reproducible in new similar groups of patients? This leads on to such notions as confidence intervals and, particularly prone to misunderstanding, significance tests.

The second role concerns the exploration and hopefully understanding of complex patterns of dependence. Such issues may arise in  particular in attempting to interpret hospital records or, very particularly, large-scale observational studies.

A rather less emphasized role of statistical thinking is in the planning of investigations. The traditional literature on this falls into some broad sections. The first has its  primary origin in the work of the statistician and geneticist R.A.Fisher encapsulated in his book The design of experiments. A second area, possibly of less direct concern in the present context, is the design of sampling procedures for the reliable estimation of features  of a population on the basis of a well-chosen sample.  Somewhat parallel    sampling procedures  do, however, arise, for example in a  laboratory  investigation in which the   purpose is to assess the properties of a large quantity of material on the basis of an appropriate sample.

In the present context, however, the main contrast is between interventionist studies, in particular randomized clinical trials, and purely observational investigations in which a  population of individuals is observed, possibly over an appreciable time span, but no intervention by the investigator takes place. That is, treatments or exposures are observed as they are,  not assigned by the investigator. An early US cardiovascular example is the Framingham study and more recent ones are the Rotterdam study, the Million  Women study and the Kardoorie (Chinese) study, the last three being very large wide ranging observational investigations.

The object of the present paper, more an extended essay than a conventional research paper, is to discuss the broad principle of study design, especially but by no means only in an epidemiological setting. Numerous illustrative examples are given. All are real, not contrived for expository purposes, but they are described merely in outline to avoid distracting detail.

Why are these issues called statistical? The specific details of each study are peculiar to that context and it is crucial that due account is taken of those details, that is of specifically subject-matter issues. Yet there are common considerations that link different investigations across many fields of study and formulation of these general ideas is part of statistical theory. While virtually all the ideas emerge from the challenges of specific applications their general formulation can be very fruitful in many ways. For example, R.A. Fisher’s work mentioned above stemmed from agricultural field trials. Bradford Hill, a pioneer in the design and implementation of randomized clinical trials, was, I   believe, at that point on friendly personal terms with Fisher and the idea of formal randomization as an allocation device certainly came from Fisher. At its best, statistical theory formulates ideas usually emanating from one field of application,  develops their consequences and puts those ideas in a form for fruitful general application.

The most successful applications hinge on merging general statistical principles seamlessly with the specific details of each new situation.

 

 

 

 

 

 

 

http://biomedfrontiers.org/ep-2016-3/

 

Clinical value of morphine, pholcodine and poppy seed IgE assays in drug-abusers and allergic people.

Allergol Immunopathol (Madr). 2011 Sep 20

Armentia A, Ruiz-Muñoz P, Quesada JM, Postigo I, Herrero M, Martín-Gil FJ, Gonzalez-Sagrado M, Martín B, Castrodeza J.

Allergy Unit, Rio Hortega University Hospital, UMDAI, Valladolid, Spain.

Abstract

BACKGROUND: The diagnosis of anaphylactic reactions due to opiates during anaesthesia can be difficult, since in most cases various drugs may have been administered. Detection of specific IgE to poppy seed might be a marker for sensitisation to opiates in allergic people and heroin-abusers. This study assessed the clinical value of morphine, pholcodine and poppy seed skin-prick and IgE determination in people suffering hypersensitivity reactions during anaesthesia or analgesia and drug-abusers with allergic symptoms.

METHODS: We selected heroin abusers and patients who suffered severe reactions during anaesthesia and analgesia from a database of 23,873 patients. The diagnostic yield (sensitivity, specificity and predictive value) of prick and IgE tests in determining opiate allergy was analysed.

RESULTS: Overall, 149 patients and 200 controls, mean age 32.9±14.7 years, were included. All patients with positive prick to opiates showed positive prick and IgE to poppy seeds, but not to morphine or pholcodine IgE. Among drug-abusers, 13/42 patients (31%) presented opium hypersensitivity confirmed by challenge tests. Among non-drug abusers, sensitisation to opiates was higher in people allergic to tobacco (25%), P<.001. Prick tests and IgE against poppy seed had a good sensitivity (95.6% and 82.6%, respectively) and specificity (98.5% and 100%, respectively) in the diagnosis of opiate allergy.

CONCLUSIONS: Opiates may be significant allergens. Drug-abusers and people sensitised to tobacco are at risk. Both the prick and specific IgE tests efficiently detected sensitisation to opiates. The highest levels were related to more-severe clinical profiles. Copyright © 2011 SEICAP. Published by Elsevier Espana. All rights reserved.

PMID: 21940094

 

 

http://biomedfrontiers.org/allergy-2013-jun-18/

Diabetologia. 2012 Nov;55(11):2920-8.

N-Acetylcysteine inhibits platelet-monocyte conjugation in patients with type 2 diabetes with depleted intraplatelet glutathione: a randomised controlled trial.

Treweeke AT, Winterburn TJ, Mackenzie I, Barrett F, Barr C, Rushworth GF, Dransfield I, MacRury SM, Megson IL.

Free Radical Research Facility, Department of Diabetes & Cardiovascular Science, University of the Highlands & Islands, Centre for Health Science, Inverness IV2 3JH, UK.


Abstract

AIMS/HYPOTHESIS: The aim of this study was to determine whether oral dosing with N-acetylcysteine (NAC) increases intraplatelet levels of the antioxidant, glutathione (GSH), and reduces platelet-monocyte conjugation in blood from patients with type 2 diabetes.

METHODS: In this placebo-controlled randomised crossover study, the effect of oral NAC dosing on platelet-monocyte conjugation and intraplatelet GSH was investigated in patients with type 2 diabetes (eligibility criteria: men or post-menopausal women with well-controlled diabetes (HbA(1c) < 10%), not on aspirin or statins). Patients (n = 14; age range 43-79 years, HbA(1c) = 6.9 ± 0.9% [52.3 ± 10.3 mmol/mol]) visited the Highland Clinical Research Facility, Inverness, UK on day 0 and day 7 for each arm of the study. Blood was sampled before and 2 h after oral administration of placebo or NAC (1,200 mg) on day 0 and day 7. Patients received placebo or NAC capsules for once-daily dosing on the intervening days. The order of administration of NAC and placebo was allocated by a central office and all patients and research staff involved in the study were blinded to the allocation until after the study was complete and the data fully analysed. The primary outcome for the study was platelet-monocyte conjugation.

RESULTS: Oral NAC reduced platelet-monocyte conjugation (from 53.1 ± 4.5% to 42.5 ± 3.9%) at 2 h after administration and the effect was maintained after 7 days of dosing. Intraplatelet GSH was raised in individuals with depleted GSH and there was a negative correlation between baseline intraplatelet GSH and platelet-monocyte conjugation. There were no adverse events.

CONCLUSIONS/INTERPRETATION: The NAC-induced normalisation of intraplatelet GSH, coupled with a reduction in platelet-monocyte conjugation, suggests that NAC might help to reduce atherothrombotic risk in type 2 diabetes.

PMID: 22935960

 

Supplement:

This important work shows that supplementation of the crucial antioxidant, glutathione (GSH), in platelets of patients with type 2 diabetes can reduce platelet conjugation to monocytes – a marker of cardiovascular risk. Importantly, the effect showed close inverse correlation with pre-existing glutathione levels in platelets, suggesting a stratified approach to utilisation of this as a prophylactic therapy in patients with type 2 diabetes. The issue is particularly important because the mainstay of anti-thrombotic therapy, aspirin, is no longer recommended in patients with type 2 diabetes who have not yet experienced a thrombotic event.

 

Ian Megson-1

Reduction in CD14+/CD41a+ (platelet-monocyte conjugate) events from a patient before (baseline) and after (2 h) oral NAC dosing.

http://biomedfrontiers.org/diabetes-2013-july-1/

Structural heterogeneity in familial Alzheimer’s disease mutants of amyloid-beta peptides.

Mol Biosyst. 2013 May;9(5):997-1003.

Chong SH, Yim J, Ham S.

Department of Chemistry, Sookmyung Women’s University, Cheongpa-ro 47-gil 100, Yongsan-Ku, Seoul 140-742, Korea.

 

Abstract

Alzheimer’s disease is a neurodegenerative disorder characterized by progressive deposition of amyloid-beta (Aβ) peptides in brain parenchyma and cerebral blood vessels. Several pathogenic familial mutations of Aβ peptides have been identified that exhibit enhanced neurotoxicity and aggregative ability. However, knowledge of the structural characteristics of those Aβ mutants is still limited. Here, we report multiple all-atom molecular dynamics simulations of the wild-type 42-residue Aβ peptide (Aβ42) and its Flemish (A21G), Arctic (E22G), Dutch (E22Q), Italian (E22K), and Iowa (D23N) familial mutants in explicit water. After validating our simulations by comparison with available experimental data, we examined common/different features in the secondary and tertiary structures of the wild-type and five familial mutants of Aβ42. We found that Aβ42 peptides display quite heterogeneous secondary and tertiary structure ensembles. Such structural heterogeneity in the monomeric state would facilitate interconversions between various secondary structures during the formation of a β-sheet-rich amyloid fibril, and may also serve as a structural basis of the amyloid polymorphism.

PMID: 23358498

http://biomedfrontiers.org/alzheimer-2013-july-15/

Angiotensin-receptor blockers and risk of Alzheimer’s disease in hypertension population–a nationwide cohort study.

Circ J. 2013;77(2):405-10.

Hsu CY, Huang CC, Chan WL, Huang PH, Chiang CH, Chen TJ, Chung CM, Lin SJ, Chen JW, Leu HB.

Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.

 

Abstract

BACKGROUND: Although emerging evidence shows angiotensin-receptor blockers (ARBs) may have a beneficial effect against Alzheimer’s disease (AD), the association is not consistent. We investigated the association between ARB use and the risk of development of AD using a nationwide, population-based cohort database in Taiwan.

METHODS AND RESULTS: In total, 16,426 newly diagnosed hypertensive patients who were administered ARB without a previous diagnosis of AD were identified from the Taiwan National Health Insurance database. The comparison group consisted of hypertensive patients who did not receive ARB, and were matched to exposed individuals using propensity score by enrolled time, age, sex, and comorbidities. During an average of 5.24 ± 2.01 years of follow-up, a total of 1,031 cases (3.13%) of new AD occurred. The log-rank test showed no significant difference in the AD occurrence rate between subjects exposed to ARBs and non-exposed controls [488 (2.97%) vs. 543 (3.29%), P=0.221]. After adjusting for age, sex, comorbidities, and medications, only advanced age [hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.12-1.13, P<0.001), female sex (HR 1.18, 95% CI 1.04-1.33, P=0.011), diabetes (HR 1.53, 95% CI 1.31-1.79, P<0.001), but not ARB (HR 1.08, 95% CI 0.96-1.22, P=0.222) were independently associated with AD development.

CONCLUSIONS: The use of ARB was not significantly associated with a reduction of risk of AD in Asian patients with essential hypertension.

PMID: 23149416

http://biomedfrontiers.org/alzheimer-2013-july-16/

Keap1 is localized in neuronal and glial cytoplasmic inclusions in various neurodegenerative diseases.

J Neuropathol Exp Neurol. 2013 Jan;72(1):18-28.

Tanji K, Maruyama A, Odagiri S, Mori F, Itoh K, Kakita A, Takahashi H, Wakabayashi K.

Department of Neuropathology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan. kunikazu@cc.hirosaki-u.ac.jp

Abstract

Oxidative stress has been proposed as a potential mechanism for neurodegenerative diseases, such as Alzheimer disease (AD), Parkinson disease (PD), and amyotrophic lateral sclerosis (ALS). In response to oxidative stress, the levels of numerous cytoprotective products are increased via alteration of the Kelch-like ECH-associated protein 1 (Keap1) and NF-E2-related factor 2 (Nrf2) system. One of the Nrf2 targets, p62, has been known to be incorporated into a wide spectrum of cytoplasmic inclusions in neurodegenerative diseases and interact with Keap1. However, it remains unclear whether Keap1 is associated with the pathogenesis of neurodegenerative diseases. In this study, we investigated the relationship between p62 and Keap1 in the brains of patients with AD, PD, dementia with Lewy bodies (DLB), and ALS. Biochemical analyses showed that p62 and Keap1 interacted with each other in AD and DLB brains and were extracted into similar detergent-soluble and -insoluble fractions. Pathologic examination demonstrated that anti-Keap1 antibodies immunostained Lewy bodies in PD and DLB, neurofibrillary tangles in AD, and skeinlike inclusions in ALS. Further analysis showed that the levels of common Nrf2 target genes were increased in AD compared with those in controls. However, there were no statistical significances in the levels of Nrf2 target genes in DLB relative to controls. Our pathologic and biochemical results suggest a molecular basis for stress response to be involved in the formation of cytoplasmic inclusions observed in several neurodegenerative diseases.

PMID: 23242280

 

http://biomedfrontiers.org/alzheimer-2013-july-17/

Identification of polypeptides in neurofibrillary tangles and total homogenates of brains with Alzheimer’s disease by tandem mass spectrometry.

J Alzheimers Dis. 2013 Jan 1;34(1):239-62.

Minjarez B, Valero Rustarazo ML, Sanchez del Pino MM, González-Robles A, Sosa-Melgarejo JA, Luna-Muñoz J, Mena R, Luna-Arias JP.

Departamento de Biología Celular, Cinvestav-IPN, Col. San Pedro Zacatenco, México, D.F., México.

Abstract

Alzheimer’s disease (AD) is the most common cause of dementia in the elderly. AD brains are characterized by the presence of neurofibrillary tangles (NFTs) and neuritic plaques. NFTs are constituted of paired helical filaments, which are structurally composed by assembled hyperphosphorylated and truncated tau polypeptides. To date, the integral constituents of NFTs remain unknown mainly due to the high insolubility of NFTs. The aim of this study was to identify by tandem mass spectrometry, the polypeptides contained in both isolated NFTs by laser capture microdissection and total homogenates, using tissue sections from paraformaldehyde-fixed AD brains. In the first case, we isolated 2,000 NFTs from tissue samples of hippocampus from each of the three Mexican AD brains used in our study. These were previously stained with anti-hyperphosphorylated tau AT-100 antibodies. After the removal of paraformaldehyde and delipidation with organic solvents, we tested three solubilization methods. We identified 102 polypeptides from total homogenates and 41 from isolated NFTs. We selected UCH-L1, transferrin, and GAPDH polypeptides to be studied by immunofluorescence and confocal microscopy. Only UCH-L1 and GAPDH colocalized with hyperphosphorylated tau in NFTs.

PMID: 23229080

http://biomedfrontiers.org/alzheimer-2013-july-18/

Endoplasmic reticulum stress occurs downstream of GluN2B subunit of N-methyl-D-aspartate receptor in mature hippocampal cultures treated with amyloid-β oligomers

Aging Cell. 2012 Oct;11(5):823-33.

Rui O. Costa, Pascale N. Lacor, Ildete L. Ferreira, Rosa Resende, Yves P. Auberson, William L. Klein, Catarina R. Oliveira, Ana C. Rego and Cláudia M. F. Pereira

CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.

Abstract:

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder affecting both the hippocampus and the cerebral cortex. Reduced synaptic density that occurs early in the disease process seems to be partially due to the overactivation of N-methyl-D-aspartate receptors (NMDARs) leading to excitotoxicity. Recently, we demonstrated that amyloid-beta oligomers (AβO), the species implicated in synaptic loss during the initial disease stages, induce endoplasmic reticulum (ER) stress in cultured neurons. Here, we investigated whether AβO trigger ER stress by an NMDAR-dependent mechanism leading to neuronal dysfunction and analyzed the contribution of GluN2A and GluN2B subunits of this glutamate receptor. Our data revealed that AβO induce ER stress in mature hippocampal cultures, activating ER stress-associated sensors and increasing the levels of the ER chaperone GRP78. We also showed that AβO induce NADPH oxidase (NOX)-mediated superoxide production downstream of GluN2B and impair ER and cytosolic Ca2+ homeostasis. These events precede changes in cell viability and activation of the ER stress-mediated apoptotic pathway, which was associated with translocation of the transcription factor GADD153/CHOP to the nucleus and occurred by a caspase-12-independent mechanism. Significantly, ER stress took place after AβO interaction with GluN2B subunits. In addition, AβO-induced ER stress and hippocampal dysfunction were prevented by ifenprodil, an antagonist of GluN2B subunits, while the GluN2A antagonist NVP-AAM077 only slightly attenuated AβO-induced neurotoxicity. Taken together, our results highlight the role of GluN2B subunit of NMDARs on ER stress-mediated hippocampal dysfunction caused by AβO suggesting that it might be a potential therapeutic target during the early stages of AD.

Key words: Alzheimer’s disease, amyloid pathology, amyloid-beta oligomers, neurodegenerative diseases, endoplasmic reticulum, N-methyl-D-aspartate receptors, GluN2B subunits, calcium homeostasis, NADPH oxidase

Link: http://www.ncbi.nlm.nih.gov/pubmed/22708890

Cláudia Pereira-png2

Proposed mechanisms for the N-methyl-D-aspartate receptor (NMDAR)-dependent endoplasmic reticulum (ER) stress induced by amyloid-beta oligomers (AβO) in mature hippocampal cells.

AβO can interact with or close to the GluN2B subunit of NMDAR (1), leading to the early rise of cytosolic Ca2+ levels (2). This increment activates NADPH oxidase (NOX) (3) and subsequently triggers the production of superoxide radicals (O2.-) (4), which in turn induces an ER stress response (5) characterized by accumulation of misfolded proteins in ER lumen (6) and ER Ca2+ depletion (7). In order to re-establish its normal functioning, cells activate ER stress sensors, including IRE1 and the downstream transcription factor XBP-1 (8) and up-regulate ER chaperones, such as GRP78 (9). However, when the AβO toxic insult is prolonged, an ER stress-mediated cell death pathway is induced increasing the levels of the pro-apoptotic transcription factor GADD153⁄CHOP in the nucleus where it triggers apoptosis (10).

 

http://biomedfrontiers.org/alzheimer-2013-july-19/

Sex and gender differences in Alzheimer’s disease: recommendations for future research.

J Womens Health (Larchmt). 2012 Oct;21(10):1018-23.

Carter CL, Resnick EM, Mallampalli M, Kalbarczyk A.

Scientific Affairs, Society for Women’s Health Research, Washington, DC 20036, USA. chris@swhr.org

Abstract

Alzheimer’s disease (AD) disproportionately affects women in both prevalence and severity; however, the biologic mechanisms underlying these sex differences are not fully understood. Sex differences in the brain, such as in brain anatomy, age-related declines in brain volume, and brain glucose metabolism, have been documented and may be important in understanding AD etiology. The full impact of sex as a basic biologic variable on this neurodegenerative disease remains elusive. To address the evidence for sex differences in AD, the Society for Women’s Health Research (SWHR) convened an interdisciplinary roundtable of experts from academia, clinical medicine, industry, and the government to discuss the state-of-the-science in sex and gender differences in AD. Roundtable participants were asked to address gaps in our knowledge and identify specific sex-based research questions for future areas of study.

PMID: 22917473

http://biomedfrontiers.org/alzheimer-2013-july-20/

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