Exercise training ameliorates cerebrovascular dysfunction in a murine model of Alzheimer's disease: role of the P2Y2 receptor and endoplasmic reticulum stress.

Cerebrovascular dysfunction is a critical risk factor for the pathogenesis of Alzheimer's disease (AD). The purinergic P2Y2 receptor and endoplasmic reticulum (ER) stress are tightly associated with vascular dysfunction and the pathogenesis of AD. However, the protective effects of exercise training on P2Y2 receptor- and ER stress-associated cerebrovascular dysfunction in AD are mostly unknown. Control (C57BL/6, CON) and AD (APP/PS1dE9, AD) mice underwent treadmill exercise training (EX). 2-MeS-ATP-induced dose-dependent vasoreactivity was determined by using a pressurized posterior cerebral artery (PCA) from 10-12-mo-old mice. Human brain microvascular endothelial cells (HBMECs) were exposed to laminar shear stress (LSS) at 20 dyn/cm2 for 30 min, 2 h, and 24 h. The expression of P2Y2 receptors, endothelial nitric oxide synthase (eNOS), and ER stress signaling were quantified by Western blot analysis. Notably, exercise converted ATP-induced vasoconstriction in the PCA from AD mice to vasodilation in AD+EX mice to a degree commensurate to the vascular reactivity observed in CON mice. Exercise reduced the expression of amyloid peptide precursor (APP) and increased the P2Y2 receptor and Akt/eNOS expression in AD mice brain. Mechanistically, LSS increased the expression of both P2Y2 receptor and eNOS protein in HBMECs, but these increases were blunted by a P2Y2 receptor antagonist in HBMECs. Exercise also reduced the expression of aberrant ER stress markers p-IRE1, p/t-eIF2α, and CHOP, as well as Bax/Bcl-2, in AD mice brain. Collectively, our results demonstrate for the first time that exercise mitigates cerebrovascular dysfunction in AD through modulating P2Y2 receptor- and ER stress-dependent endothelial dysfunction.NEW & NOTEWORTHY A limited study has investigated whether exercise training can improve cerebrovascular function in Alzheimer's disease. The novel findings of the study are that exercise training improves cerebrovascular dysfunction through enhancing P2Y2 receptor-mediated eNOS signaling and reducing ER stress-associated pathways in AD. These data suggest that exercise training, which regulates P2Y2 receptor and ER stress in AD brain, is a potential therapeutic strategy for Alzheimer's disease.

Characterization of Polymyxin B Biodistribution and Disposition in an Animal Model.

Despite dose-limiting nephrotoxicity concerns, polymyxin B has resurged as the treatment of last resort for multidrug-resistant Gram-negative bacterial infections. However, the pharmacokinetic, pharmacodynamic, and nephrotoxic properties of polymyxin B still are not thoroughly understood. The objective of this study was to provide additional insights into the overall biodistribution and disposition of polymyxin B in an animal model. Sprague-Dawley rats were dosed with intravenous polymyxin B (3 mg/kg of body weight). Drug concentrations in the serum, urine, bile, and tissue (brain, heart, lungs, liver, spleen, kidneys, and skeletal muscle) samples over time were assayed by a validated methodology. Among all the organs evaluated, polymyxin B distribution was highest in the kidneys. The mean renal tissue/serum polymyxin B concentration ratios were 7.45 (95% confidence interval [CI], 4.63 to 10.27) at 3 h and 19.62 (95% CI, 5.02 to 34.22) at 6 h postdose. Intrarenal drug distribution was examined by immunostaining. Using a ratiometric analysis, proximal tubular cells showed the highest accumulation of polymyxin B (Mander's overlap coefficient, 0.998) among all cell types evaluated. Less than 5% of the administered dose was recovered in urine over 48 h, but all 4 major polymyxin B components were detected in the bile over 4 h. These findings corroborate previous results that polymyxin B is highly accumulated in the kidneys, but the elimination likely is via a nonrenal route. Biliary excretion could be one of the routes of polymyxin B elimination, and this should be further explored. The elucidation of mechanism(s) of drug uptake in proximal tubular cells is ongoing.

The neuroendocrine protein 7B2 suppresses the aggregation of neurodegenerative disease-related proteins.

Neurodegenerative diseases such as Alzheimer (AD) and Parkinson (PD) are characterized by abnormal aggregation of misfolded ß-sheet-rich proteins, including amyloid-ß (Aß)-derived peptides and tau in AD and α-synuclein in PD. Correct folding and assembly of these proteins are controlled by ubiquitously expressed molecular chaperones; however, our understanding of neuron-specific chaperones and their involvement in the pathogenesis of neurodegenerative diseases is limited. We here describe novel chaperone-like functions for the secretory protein 7B2, which is widely expressed in neuronal and endocrine tissues. In in vitro experiments, 7B2 efficiently prevented fibrillation and formation of Aß(1-42), Aß(1-40), and α-synuclein aggregates at a molar ratio of 1:10. In cell culture experiments, inclusion of recombinant 7B2, either in the medium of Neuro-2A cells or intracellularly via adenoviral 7B2 overexpression, blocked the neurocytotoxic effect of Aß(1-42) and significantly increased cell viability. Conversely, knockdown of 7B2 by RNAi increased Aß(1-42)-induced cytotoxicity. In the brains of APP/PSEN1 mice, a model of AD amyloidosis, immunoreactive 7B2 co-localized with aggregation-prone proteins and their respective aggregates. Furthermore, in the hippocampus and substantia nigra of human AD- and PD-affected brains, 7B2 was highly co-localized with Aß plaques and α-synuclein deposits, strongly suggesting physiological association. Our data provide insight into novel functions of 7B2 and establish this neural protein as an anti-aggregation chaperone associated with neurodegenerative disease.

A novel function for proSAAS as an amyloid anti-aggregant in Alzheimer's disease.

Neurodegenerative diseases such as Alzheimer's disease (AD) are characterized by an abnormal aggregation of misfolded beta-sheet rich proteins such as ß-amyloid (Aß). Various ubiquitously expressed molecular chaperones control the correct folding of cellular proteins and prevent the accumulation of harmful species. We here describe a novel anti-aggregant chaperone function for the neuroendocrine protein proSAAS, an abundant secretory polypeptide that is widely expressed within neural and endocrine tissues and which has previously been associated with neurodegenerative disease in various proteomics studies. In the brains of 12-month-old APdE9 mice, and in the cortex of a human AD-affected brain, proSAAS immunoreactivity was highly colocalized with amyloid pathology. Immunoreactive proSAAS co-immunoprecipitated with Aß immunoreactivity in lysates from APdE9 mouse brains. In vitro, proSAAS efficiently prevented the fibrillation of Aß(1-42) at molar ratios of 1 : 10, and this anti-aggregation effect was dose dependent. Structure-function studies showed that residues 97-180 were sufficient for the anti-aggregation function against Aß. Finally, inclusion of recombinant proSAAS in the medium of Neuro2a cells, as well as lentiviral-mediated proSAAS over-expression, blocked the neurocytotoxic effect of Aß(1-42) in Neuro2a cells. Taken together, our results suggest that proSAAS may play a role in Alzheimer's disease pathology.

Regular exercise prevents non-cognitive disturbances in a rat model of Alzheimer's disease.

Previously, we reported that in a rat model of sporadic Alzheimer's disease (AD) generated by exogenous administration of Aß1₋42 (250 pmol/d for 2 wk) via mini-osmotic pump, the animals exhibited learning and memory impairment, which could be attributed to the deleterious alterations in the levels of cognition-related signalling molecules. We showed that 4 wk of treadmill exercise totally prevented these impairments. Here, we evaluated the effect of exercise on non-cognitive function and basal synaptic transmission in the Cornu Ammonis 1 (CA1) area using the same AD model. Our results indicated that the anxiety behaviour of Aß-treated rats was prevented by 4 wk of treadmill exercise. Exercised/Aß-infused rats spent a longer time in the centre area of the open field (OF), elevated plus maze (EPM) paradigms and the light area of the light-dark (LD) box, which were similar to those of control and exercise rats. Furthermore, under basal conditions the aberrant up-regulation of calcineurin (PP2B) and reduction of phosphorylated Ca²âº/calmodulin dependent protein kinase II (p-CaMKII) levels induced by AD-like pathology were normalised by the exercise regimen. We conclude that regular exercise may exert beneficial effects on both cognitive and non-cognitive functions in this AD model.

ß2-Adrenoceptor agonists are required for development of the asthma phenotype in a murine model.

ß(2)-Adrenoceptor (ß2AR) agonists are the most effective class of bronchodilators and a mainstay of asthma management. The first potent ß2AR agonist discovered and widely used in reversing the airway constriction associated with asthma exacerbation was the endogenous activator of the ß2AR, epinephrine. In this study, we demonstrate that activation of the ß2AR by epinephrine is paradoxically required for development of the asthma phenotype. In an antigen-driven model, mice sensitized and challenged with ovalbumin showed marked elevations in three cardinal features of the asthma phenotype: inflammatory cells in their bronchoalveolar lavage fluid, mucin over production, and airway hyperresponsiveness. However, genetic depletion of epinephrine using mice lacking the enzyme to synthesize epinephrine, phenylethanolamine N-methyltransferase, or mice that had undergone pharmacological sympathectomy with reserpine to deplete epinephrine, had complete attenuation of these three cardinal features of the asthma phenotype. Furthermore, administration of the long-acting ß2AR agonist, formoterol, a drug currently used in asthma treatment, to phenylethanolamine N-methyltransferase-null mice restored the asthma phenotype. We conclude that ß2AR agonist-induced activation is needed for pathogenesis of the asthma phenotype. These findings also rule out constitutive signaling by the ß2AR as sufficient to drive the asthma phenotype, and may help explain why chronic administration of ß2AR agonists, such as formoterol, have been associated with adverse outcomes in asthma. These data further support the hypothesis that chronic asthma management may be better served by treatment with certain "ß-blockers."

Diverse compounds mimic Alzheimer disease-causing mutations by augmenting Abeta42 production.

Increased Abeta42 production has been linked to the development of Alzheimer disease. We now identify a number of compounds that raise Abeta42. Among the more potent Abeta42-raising agents identified are fenofibrate, an antilipidemic agent, and celecoxib, a COX-2-selective NSAID. Many COX-2-selective NSAIDs tested raised Abeta42, including multiple COX-2-selective derivatives of two Abeta42-lowering NSAIDs. Compounds devoid of COX activity and the endogenous isoprenoids FPP and GGPP also raised Abeta42. These compounds seem to target the gamma-secretase complex, increasing gamma-secretase-catalyzed production of Abeta42 in vitro. Short-term in vivo studies show that two Abeta42-raising compounds increase Abeta42 levels in the brains of mice. The elevations in Abeta42 by these compounds are comparable to the increases in Abeta42 induced by Alzheimer disease-causing mutations in the genes encoding amyloid beta protein precursor and presenilins, raising the possibility that exogenous compounds or naturally occurring isoprenoids might increase Abeta42 production in humans.

1-Indanone and 1,3-indandione Derivatives as Ligands for Misfolded α-Synuclein Aggregates.

The development of imaging agents for in vivo detection of alpha-synuclein (α-syn) pathologies faces several challenges. A major gap in the field is the lack of diverse molecular scaffolds with high affinity and selectivity to α-syn fibrils for in vitro screening assays. Better in vitro scaffolds can instruct the discovery of better in vivo agents. We report the rational design, synthesis, and in vitro evaluation of a series of novel 1-indanone and 1,3-indandione derivatives from a Structure-Activity Relationship (SAR) study centered on some existing α-syn fibril binding ligands. Our results from fibril saturation binding experiments show that two of the lead candidates compounds 8 and 32 bind α-syn fibrils with binding constants (Kd ) of 9.0 and 18.8 nM, respectively, and selectivity of greater than 10× for α-syn fibrils compared with amyloid-ß (Aß) and tau fibrils. Our results demonstrate that the lead ligands avidly label all forms of α-syn on PD brain tissue sections, but only the dense core of senile plaques in AD brain tissue, respectively. These results are corroborated by ligand-antibody colocalization data from Syn211, which shows immunoreactivity toward all forms of α-syn aggregates, and Syn303, which displays preferential reactivity toward mature Lewy pathology. Our results reveal that 1-indanone derivatives have desirable properties for the biological evaluation of α-synucleinopathies.

Prostacyclin Promotes Degenerative Pathology in a Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is the most common form of dementia in aged populations. A substantial amount of data demonstrates that chronic neuroinflammation can accelerate neurodegenerative pathologies. In AD, chronic neuroinflammation results in the upregulation of cyclooxygenase and increased production of prostaglandin H2, a precursor for many vasoactive prostanoids. While it is well-established that many prostaglandins can modulate the progression of neurodegenerative disorders, the role of prostacyclin (PGI2) in the brain is poorly understood. We have conducted studies to assess the effect of elevated prostacyclin biosynthesis in a mouse model of AD. Upregulated prostacyclin expression significantly worsened multiple measures associated with amyloid-ß (Aß) disease pathologies. Mice overexpressing both Aß and PGI2 exhibited impaired learning and memory and increased anxiety-like behavior compared with non-transgenic and PGI2 control mice. PGI2 overexpression accelerated the development of Aß accumulation in the brain and selectively increased the production of soluble Aß42. PGI2 damaged the microvasculature through alterations in vascular length and branching; Aß expression exacerbated these effects. Our findings demonstrate that chronic prostacyclin expression plays a novel and unexpected role that hastens the development of the AD phenotype.

A surrogate marker for very early-stage tau pathology is detectable by molecular magnetic resonance imaging.

The abnormal phosphorylation of tau is a necessary precursor to the formation of tau fibrils, a marker of Alzheimer's disease. We hypothesize that hyperphosphorylative conditions may result in unique cell surface markers. We identify and demonstrate the utility of such surrogate markers to identify the hyperphosphorylative state. Methods: Cell SELEX was used to identify novel thioaptamers specifically binding hyperphosphorylative cells. Cell surface vimentin was identified as a potential binding target of the aptamer. Novel molecular magnetic resonance imaging (M-MRI) probes using these aptamers and a small molecule ligand to vimentin were used for in vivo detection of this pre-pathological state. Results: In a mouse model of pathological tau, we demonstrated in vivo visualization of the hyperphosphorylative state by M-MRI, enabling the identification at a pre-pathological stage of mice that develop frank tau pathology several months later. In vivo visualization of the hyperphosphorylative state by M-MRI was further validated in a second mouse model (APP/PS1) of Alzheimer's disease again identifying the mutants at a pre-pathological stage. Conclusions: M-MRI of the hyperphosphorylative state identifies future tau pathology and could enable extremely early-stage diagnosis of Alzheimer's disease, at a pre-patholgical stage.

Common variation in the miR-659 binding-site of GRN is a major risk factor for TDP43-positive frontotemporal dementia.

Loss-of-function mutations in progranulin (GRN) cause ubiquitin- and TAR DNA-binding protein 43 (TDP-43)-positive frontotemporal dementia (FTLD-U), a progressive neurodegenerative disease affecting approximately 10% of early-onset dementia patients. Here we expand the role of GRN in FTLD-U and demonstrate that a common genetic variant (rs5848), located in the 3'-untranslated region (UTR) of GRN in a binding-site for miR-659, is a major susceptibility factor for FTLD-U. In a series of pathologically confirmed FTLD-U patients without GRN mutations, we show that carriers homozygous for the T-allele of rs5848 have a 3.2-fold increased risk to develop FTLD-U compared with homozygous C-allele carriers (95% CI: 1.50-6.73). We further demonstrate that miR-659 can regulate GRN expression in vitro, with miR-659 binding more efficiently to the high risk T-allele of rs5848 resulting in augmented translational inhibition of GRN. A significant reduction in GRN protein was observed in homozygous T-allele carriers in vivo, through biochemical and immunohistochemical methods, mimicking the effect of heterozygous loss-of-function GRN mutations. In support of these findings, the neuropathology of homozygous rs5848 T-allele carriers frequently resembled the pathological FTLD-U subtype of GRN mutation carriers. We suggest that the expression of GRN is regulated by miRNAs and that common genetic variability in a miRNA binding-site can significantly increase the risk for FTLD-U. Translational regulation by miRNAs may represent a common mechanism underlying complex neurodegenerative disorders.

Multiplex protein-specific microscopy with ultraviolet surface excitation.

Immunohistochemical techniques, such as immunofluorescence (IF) staining, enable microscopic imaging of local protein expression within tissue samples. Molecular profiling enabled by IF is critical to understanding pathogenesis and is often involved in complex diagnoses. A recent innovation, known as microscopy with ultraviolet surface excitation (MUSE), uses deep ultraviolet (≈280 nm) illumination to excite labels at the tissue surface, providing equivalent images without fixation, embedding, and sectioning. However, MUSE has not yet been integrated into traditional IF pipelines. This limits its application in more complex diagnoses that rely on protein-specific markers. This paper aims to broaden the applicability of MUSE to multiplex immunohistochemistry using quantum dot nanoparticles. We demonstrate the advantages of quantum dot labels for protein-specific MUSE imaging on both paraffin-embedded and intact tissue, significantly expanding MUSE applicability to protein-specific applications. Furthermore, with recent innovations in three-dimensional ultraviolet fluorescence microscopy, this opens the door to three-dimensional IF imaging with quantum dots using ultraviolet excitation.

Three-Dimensional Microscopy by Milling with Ultraviolet Excitation.

Analysis of three-dimensional biological samples is critical to understanding tissue function and the mechanisms of disease. Many chronic conditions, like neurodegenerative diseases and cancers, correlate with complex tissue changes that are difficult to explore using two-dimensional histology. While three-dimensional techniques such as confocal and light-sheet microscopy are well-established, they are time consuming, require expensive instrumentation, and are limited to small tissue volumes. Three-dimensional microscopy is therefore impractical in clinical settings and often limited to core facilities at major research institutions. There would be a tremendous benefit to providing clinicians and researchers with the ability to routinely image large three-dimensional tissue volumes at cellular resolution. In this paper, we propose an imaging methodology that enables fast and inexpensive three-dimensional imaging that can be readily integrated into current histology pipelines. This method relies on block-face imaging of paraffin-embedded samples using deep-ultraviolet excitation. The imaged surface is then ablated to reveal the next tissue section for imaging. The final image stack is then aligned and reconstructed to provide tissue models that exceed the depth and resolution achievable with modern three-dimensional imaging systems.

Robust Tracing and Visualization of Heterogeneous Microvascular Networks.

Advances in high-throughput imaging allow researchers to collect three-dimensional images of whole organ microvascular networks. These extremely large images contain networks that are highly complex, time consuming to segment, and difficult to visualize. In this paper, we present a framework for segmenting and visualizing vascular networks from terabyte-sized three-dimensional images collected using high-throughput microscopy. While these images require terabytes of storage, the volume devoted to the fiber network is ≈ 4 percent of the total volume size. While the networks themselves are sparse, they are tremendously complex, interconnected, and vary widely in diameter. We describe a parallel GPU-based predictor-corrector method for tracing filaments that is robust to noise and sampling errors common in these data sets. We also propose a number of visualization techniques designed to convey the complex statistical descriptions of fibers across large tissue sections-including commonly studied microvascular characteristics, such as orientation and volume.

Caught in the act: alpha-synuclein is the culprit in Parkinson's disease.

Previous reports on Parkinson's disease indicate that genetic mutations in alpha-synuclein result in the aberrant accumulation of this protein, causing toxic gain of function leading to the development of Parkinson's. A recent report on the Iowan kindred, an extended pedigree with an autosomal dominant form of this disease, provides new mechanistic insight into Parkinson's disease by showing that an elevation in wild-type alpha-synuclein protein is sufficient to develop the early-onset form of the disorder. This review discusses how insights gained from these studies of alpha-synuclein may direct future research into Parkinson's disease.

Progranulin: normal function and role in neurodegeneration.

Progranulin (PGRN) is a multifunctional protein that has attracted significant attention in the neuroscience community following the recent discovery of PGRN mutations in some cases of frontotemporal dementia. Most of the pathogenic mutations result in null alleles, and it is thought that frontotemporal dementia in these families results from PGRN haploinsufficiency. The neuropathology associated with PGRN mutations is characterized by the presence of tau-negative, ubiquitin-immunoreactive neuronal inclusions (frontotemporal lobar degeneration with ubiquitinated inclusions) that are also positive for the transactivation response DNA binding protein with M(r) 43 kD. The clinical phenotype includes behavioral abnormalities, language disorders and parkinsonism but not motor neuron disease. There is significant clinical variation between families with different PGRN mutations and among members of individual families. The normal function of PGRN is complex, with the full-length form of the protein having trophic and anti-inflammatory activity, whereas proteolytic cleavage generates granulin peptides that promote inflammatory activity. In the periphery, PGRN functions in wound healing responses and modulates inflammatory events. In the CNS, PGRN is expressed by neurons and microglia; consequently, reduced levels of PGRN could affect both neuronal survival and CNS inflammatory processes. In this review, we discuss current knowledge of the molecular genetics, neuropathology, clinical phenotype and functional aspects of PGRN in the context of neurodegenerative disease.

Plasmonic nanoparticle-based expansion microscopy with surface-enhanced Raman and dark-field spectroscopic imaging.

Fluorescence-based expansion microscopy (ExM) is a new technique which can yield nanoscale resolution of biological specimen on a conventional fluorescence microscope through physical sample expansion up to 20 times its original dimensions while preserving structural information. It however inherits known issues of fluorescence microscopy such as photostability and multiplexing capabilities, as well as an ExM-specific issue in signal intensity reduction due to a dilution effect after expansion. To address these issues, we propose using antigen-targeting plasmonic nanoparticle labels which can be imaged using surface-enhanced Raman scattering spectroscopy (SERS) and dark-field spectroscopy. We demonstrate that the nanoparticles enable multimodal imaging: bright-field, dark-field and SERS, with excellent photostability, contrast enhancement and brightness.

7B2 chaperone knockout in APP model mice results in reduced plaque burden.

Impairment of neuronal proteostasis is a hallmark of Alzheimer's and other neurodegenerative diseases. However, the underlying molecular mechanisms leading to pathogenic protein aggregation, and the role of secretory chaperone proteins in this process, are poorly understood. We have previously shown that the neural-and endocrine-specific secretory chaperone 7B2 potently blocks in vitro fibrillation of Aß42. To determine whether 7B2 can function as a chaperone in vivo, we measured plaque formation and performed behavioral assays in 7B2-deficient mice in an hAPPswe/PS1dE9 Alzheimer's model mouse background. Surprisingly, immunocytochemical analysis of cortical levels of thioflavin S- and Aß-reactive plaques showed that APP mice with a partial or complete lack of 7B2 expression exhibited a significantly lower number and burden of thioflavin S-reactive, as well as Aß-immunoreactive, plaques. However, 7B2 knockout did not affect total brain levels of either soluble or insoluble Aß. While hAPP model mice performed poorly in the Morris water maze, their brain 7B2 levels did not impact performance. Since 7B2 loss reduced amyloid plaque burden, we conclude that brain 7B2 can impact Aß disposition in a manner that facilitates plaque formation. These results are reminiscent of prior findings in hAPP model mice lacking the ubiquitous secretory chaperone clusterin.

NSAIDs and enantiomers of flurbiprofen target gamma-secretase and lower Abeta 42 in vivo.

Epidemiologic studies demonstrate that long-term use of NSAIDs is associated with a reduced risk for the development of Alzheimer disease (AD). In this study, 20 commonly used NSAIDs, dapsone, and enantiomers of flurbiprofen were analyzed for their ability to lower the level of the 42-amino-acid form of amyloid beta protein (Abeta42) in a human H4 cell line. Thirteen of the NSAIDs and the enantiomers of flurbiprofen were then tested in acute dosing studies in amyloid beta protein precursor (APP) transgenic mice, and plasma and brain levels of Abeta and the drug were evaluated. These studies show that (a). eight FDA-approved NSAIDs lower Abeta42 in vivo, (b). the ability of an NSAID to lower Abeta42 levels in cell culture is highly predicative of its in vivo activity, (c). in vivo Abeta42 lowering in mice occurs at drug levels achievable in humans, and (d). there is a significant correlation between Abeta42 lowering and levels of ibuprofen. Importantly, flurbiprofen and its enantiomers selectively lower Abeta42 levels in broken cell gamma-secretase assays, indicating that these compounds directly target the gamma-secretase complex that generates Abeta from APP. Of the compounds tested, meclofenamic acid, racemic flurbiprofen, and the purified R and S enantiomers of flurbiprofen lowered Abeta42 levels to the greatest extent. Because R-flurbiprofen reduces Abeta42 levels by targeting gamma-secretase and has reduced side effects related to inhibition of cyclooxygenase (COX), it is an excellent candidate for clinical testing as an Abeta42 lowering agent.

Chronic administration of R-flurbiprofen attenuates learning impairments in transgenic amyloid precursor protein mice.

BACKGROUND: Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced incidence of Alzheimer's disease (AD). We and others have shown that certain NSAIDs reduce secretion of Abeta42 in cell culture and animal models, and that the effect of NSAIDs on Abeta42 is independent of the inhibition of cyclooxygenase by these compounds. Since Abeta42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower Abeta42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil) as a selective Abeta42 lowering agent with greatly reduced cyclooxygenase activity that shows promise for testing this hypothesis. In this study we report the effect of chronic R-flurbiprofen treatment on cognition and Abeta loads in Tg2576 APP mice. RESULTS: A four-month preventative treatment regimen with R-flurbiprofen (10 mg/kg/day) was administered to young Tg2576 mice prior to robust plaque or Abeta pathology. This treatment regimen improved spatial learning as assessed by the Morris water maze, indicated by an increased spatial bias during the third probe trial and an increased utilization of a place strategy to solve the water maze. These results are consistent with an improvement in hippocampal- and medial temporal lobe-dependent memory function. A modest, though not statistically significant, reduction in formic acid-soluble levels of Abeta was also observed. To determine if R-flurbiprofen could reverse cognitive deficits in Tg2576 mice where plaque pathology was already robust, a two-week therapeutic treatment was given to older Tg2576 mice with the same dose of R-flurbiprofen. This approach resulted in a significant decrease in Abeta plaque burden but no significant improvement in spatial learning. CONCLUSION: We have found that chronic administration of R-flurbiprofen is able to attenuate spatial learning deficits if given prior to plaque deposition in Tg2576 mice. Given its ability to selectively target Abeta42 production and improve cognitive impairments in transgenic APP mice, as well as promising data from a phase 2 human clinical trial, future studies are needed to investigate the utility of R-flurbiprofen as an AD therapeutic and its possible mechanisms of action.