Clinical trial of indomethacin in Alzheimer's disease

Catalytic antioxidants and neurodegeneration

Oxidative stress, resulting from mitochondrial dysfunction, excitotoxicity, or neuroinflammation, is implicated in numerous neurodegenerative conditions. Damage due to superoxide, hydroxyl radical, and peroxynitrite has been observed in diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as in acute conditions that lead to neuronal death, such as stroke and epilepsy. Antioxidant therapies to remove these toxic compounds have been of great interest in treating these disorders. Catalytic antioxidants mimic the activities of superoxide dismutase or catalase or both, detoxifying superoxide and hydrogen peroxide, and in some cases, peroxynitrite and other toxic species as well. Several compounds have demonstrated efficacy in in vitro and in animal models of neurodegeneration, leading to optimism that catalytic antioxidants may prove to be useful therapies in human disease.

Cyclooxygenase-1 null mice show reduced neuroinflammation in response to beta-amyloid

Several independent epidemiological studies indicate that chronic use of non-steroidal anti-inflammatory drugs can reduce the risk of developing Alzheimer's disease (AD), supporting the inflammatory cascade hypothesis. Although the first clinical trial with indomethacin, a preferential cyclooxygenase (COX)-1 inhibitor, showed beneficial effects, subsequent large clinical trials, mostly using COX-2 inhibitors, failed to show any beneficial effect in AD patients with mild to severe cognitive impairment. These combined data suggest that either an early treatment is crucial to stop the mechanisms underlying the disease before the onset of the symptoms, or that preferential COX-1 inhibition, rather than COX-2, is beneficial. Therefore, a full understanding of the physiological, pathological, and/or neuroprotective role of COX isoforms may help to develop better therapeutic strategies for the prevention or treatment of AD. In this study, we examined the effect of COX-1 genetic deletion on the inflammatory response and neurodegeneration induced by β-amyloid. β-amyloid (Aβ_1-42) was centrally injected in the lateral ventricle of COX-1-deficient (COX-1^-/-) and their respective wild-type (WT) mice. In COX-1^-/- mice, Aβ_1-42-induced inflammatory response and neuronal damage were attenuated compared to WT mice, as shown by Fluoro-Jade B and nitrotyrosine staining. These results indicate that inhibition of COX-1 activity may be valid therapeutic strategy to reduce brain inflammatory response and neurodegeneration.

Toll-like receptors in Alzheimer's disease

Alzheimer's disease (AD) is characterized by the formation of insoluble deposits of beta-amyloid (Abeta) within the parenchyma of the brain. These deposits are associated with a robust microglia-mediated inflammatory response. Recent work has demonstrated that Toll-like receptors (TLRs) participate in this inflammatory response. This chapter reviews the mechanisms whereby TLRs contribute to the induction of a microglial inflammatory response to promote AD pathogenesis. Specifically, the involvement of CD14 and the TLRs in microglial activation is delineated. The TLR-mediated microglial response has beneficial roles in stimulating phagocytosis as well as detrimental roles in the Abeta-stimulated release of neurotoxic products.

NADPH oxidase as a therapeutic target in Alzheimer's disease

At present, available treatments for Alzheimer's disease (AD) are largely unable to halt disease progression. Microglia, the resident macrophages in the brain, are strongly implicated in the pathology and progressively degenerative nature of AD. Specifically, microglia are activated in response to both beta amyloid (Abeta) and neuronal damage, and can become a chronic source of neurotoxic cytokines and reactive oxygen species (ROS). NADPH oxidase is a multi-subunit enzyme complex responsible for the production of both extracellular and intracellular ROS by microglia. Importantly, NADPH oxidase expression is upregulated in AD and is an essential component of microglia-mediated Abeta neurotoxicity. Activation of microglial NADPH oxidase causes neurotoxicity through two mechanisms: 1) extracellular ROS produced by microglia are directly toxic to neurons; 2) intracellular ROS function as a signaling mechanism in microglia to amplify the production of several pro-inflammatory and neurotoxic cytokines (for example, tumor necrosis factor-alpha, prostaglandin E2, and interleukin-1beta). The following review describes how targeting NADPH oxidase can reduce a broad spectrum of toxic factors (for example, cytokines, ROS, and reactive nitrogen species) to result in inhibition of neuronal damage from two triggers of deleterious microglial activation (Abeta and neuron damage), offering hope in halting the progression of AD.

Cognitive and cerebral metabolic effects of celecoxib versus placebo in people with age-related memory loss: randomized controlled study

OBJECTIVE

Because anti-inflammatory drugs may delay cognitive decline and influence brain metabolism in normal aging, the authors determined the effects of the cyclooxygenase-2 inhibitor, celecoxib, on cognitive performance and regional cerebral glucose metabolism in nondemented volunteers with mild age-related memory decline.

DESIGN

Randomized, double-blind, placebo-controlled, parallel group trial with 18-months of exposure to study medication.

SETTING

University research institute.

PARTICIPANTS

Eighty-eight subjects, aged 40-81 years (mean: 58.7, SD: 8.9 years) with mild self-reported memory complaints but normal memory performance scores were recruited from community physician referrals, media coverage, and advertising. Forty subjects completed the study.

INTERVENTIONS

Daily celecoxib dose of 200 or 400 mg, or placebo.

MAIN OUTCOME MEASURES

Standardized neuropsychological test battery and statistical parametric mapping (SPM) of FDG-PET scans performed during mental rest.

RESULTS

Measures of cognition showed significant between-group differences in executive functioning (F [1, 30] = 5.06, p = 0.03) and language/semantic memory (F [1, 31] = 6.19, p = 0.02), favoring the celecoxib group compared with the placebo group. Concomitantly, FDG-PET scans demonstrated bilateral metabolic increases in prefrontal cortex in the celecoxib group in the vicinity of Brodmann's areas 9 and 10, but not in the placebo group. SPM analyses of the PET data pooled by treatment arm corresponded to a 6% increase in activity over pretreatment levels (p <0.01, after adjustment for multiple comparisons).

CONCLUSIONS

These results suggest that daily celecoxib use may improve cognitive performance and increase regional brain metabolism in people with age-associated memory decline.

Inflammaging as a prodrome to Alzheimer's disease

Recently, the term "inflammaging" was coined by Franceshci and colleagues to characterize a widely accepted paradigm that ageing is accompanied by a low-grade chronic up-regulation of certain pro-inflammatory responses. Inflammaging differs significantly from the traditional five cardinal features of acute inflammation in that it is characterized by a relative decline in adaptive immunity and T-helper 2 responses and is associated with increased innate immunity by cells of the mononuclear phagocyte lineage. While the over-active innate immunity characteristic of inflammaging may remain subclinical in many elderly individuals, a portion of individuals (postulated to have a "high responder inflammatory genotype") may shift from a state of "normal" or "subclinical" inflammaging to one or more of a number of age-associated diseases. We and others have found that IFN-γ and other pro-inflammatory cytokines interact with processing and production of Aβ peptide, the pathological hallmark feature of Alzheimer's disease (AD), suggesting that inflammaging may be a "prodrome" to AD. Although conditions of enhanced innate immune response with overproduction of pro-inflammatory proteins are associated with both healthy aging and AD, it is suggested that those who age "well" demonstrate anti-inflammaging mechanisms and biomarkers that likely counteract the adverse immune response of inflammaging. Thus, opposing the features of inflammaging may prevent or treat the symptoms of AD. In this review, we fully characterize the aging immune system. In addition, we explain how three novel treatments, (1) human umbilical cord blood cells (HUCBC), (2) flavanoids, and (3) Aβ vaccination oppose the forces of inflammaging and AD-like pathology in various mouse models.

The inflammatory response in Alzheimer's disease

Over the last 2 decades, numerous innate inflammatory mediators have been reported to be upregulated in pathologically vulnerable regions of the brain in Alzheimer's disease (AD). These data have led to a reexamination of the dogma of brain immunologic privilege and to new studies that examine the role of the innate inflammatory response in a number of other neurologic disorders, particularly Parkinson's disease and human immunodeficiency virus dementia. In addition, basic science discoveries about neuroinflammation are now beginning to move to the clinic. More than 20 epidemiologic surveys have consistently demonstrated that common non-steroidal anti-inflammatory drugs may protect against the development of AD. By contrast, anti-inflammatory treatment trials for existing AD have typically shown little to no effect on halting or reversing the disorder, although the agents tested have often been at odds with those suggested by the epidemiologic and basic science results. The extensive literature on innate inflammation and neurologic disease notwithstanding, three fundamental questions still remain to be answered fully. First, are innate inflammatory responses a cause of neurologic disease or merely a more sophisticated means than previously imagined for removing the detritus left by more primary pathogenic mechanisms? Second, can anti-inflammatory agents effectively treat existing neurologic disease, or is a protective strategy in high-risk patients the only reasonable option? Third, whether for protection or treatment, what is the best choice of anti-inflammatory agent given the basic science mechanisms and epidemiologic results that have been reported?

Developing new treatments for Alzheimer's disease: the who, what, when, and how of biomarker-guided therapies

This synthetic review presents an approach to the use of biomarkers for the development of new treatments for Alzheimer's disease (AD). After reviewing the process of translation as applied to AD, the paper provides a general update on what is known about the biology of the disease, and highlights currently available treatments. This is followed by a discussion of future drug development for AD emphasizing the roles that biomarkers are likely to play in this process: (1) define patients who are going to progress rapidly for the purpose of trial enrichment; (2) differentiate disease and therapeutically relevant AD subtypes; (3) assess the potential activity of specific therapies in vivo or ex vivo; and (4) measure the underlying disease state, so as to (a) detect disease and assess drug response in asymptomatic patients, (b) serve as a secondary outcome measure in clinical trials of symptomatic patients, and (c) decide if further development of a treatment should be stopped if not likely to be effective. Several examples are used to illustrate each biomarker utility in the AD context.

Blueberry opposes beta-amyloid peptide-induced microglial activation via inhibition of p44/42 mitogen-activation protein kinase

Alzheimer's Disease (AD) is the most common age-related dementia, with a current prevalence in excess of five million individuals in the United States. The aggregation of amyloid-beta (A beta) into fibrillar amyloid plaques is a key pathological event in the development of the disease. Microglial proinflammatory activation is widely known to cause neuronal and synaptic damage that correlates with cognitive impairment in AD. However, current pharmacological attempts at reducing neuroinflammation mediated via microglial activation have been largely negative in terms of slowing AD progression. Previously, we have shown that microglia express proinflammatory cytokines and a reduced capacity to phagocytose A beta in the context of CD40, A beta peptides and/or lipopolysaccharide (LPS) stimulation, a phenomenon that can be opposed by attenuation of p44/42 mitogen-activated protein kinase (MAPK) signaling. Other groups have found that blueberry (BB) extract both inhibits phosphorylation of this MAPK module and also improves cognitive deficits in AD model mice. Given these considerations and the lack of reduced A beta quantities in behaviorally improved BB-fed mice, we wished to determine whether BB supplementation would alter the microglial proinflammatory activation state in response to A beta. We found that BB significantly enhances microglial clearance of A beta, inhibits aggregation of A beta(1-42), and suppresses microglial activation, all via suppression of the p44/42 MAPK module. Thus, these data may explain the previously observed behavioral recovery in PSAPP mice and suggest a means by which dietary supplementation could mitigate an undesirable microglial response toward fibrillar A beta.

Interleukin-6 covaries inversely with hippocampal grey matter volume in middle-aged adults

BACKGROUND

Converging animal findings suggest that higher peripheral levels of inflammation are associated with activation of central inflammatory mechanisms that result in hippocampal neurodegeneration and related impairment of memory function. We have recently shown, consistent with animal findings, an inverse association between peripheral levels of interleukin-6 (IL-6), a relatively stable marker of systemic inflammation, and memory function in mid-life adults. In the current study, we extend this work to test whether systemic inflammation is associated with reduced grey matter volume of the hippocampus.

METHODS

For this purpose, we used a computational structural neuroimaging method (optimized voxel-based morphometry) to evaluate the relationship between plasma IL-6 levels and hippocampal grey matter volume in a sample of 76 relatively healthy community volunteers ages 30-54.

RESULTS

Peripheral levels of IL-6 covaried inversely with hippocampal grey matter volume, and this relationship persisted after accounting for several possible confounders, including age, gender, race, years of education, percent body fat, blood pressure, smoking, physical activity, hours of sleep, alcohol use, and total grey matter volume.

CONCLUSIONS

To our knowledge, this is the first report of a relationship between a peripheral marker of IL-6 and hippocampal grey matter volume, raising the possibility that low-grade systemic inflammation could plausibly presage subclinical cognitive decline in part via structural neural pathways.

Age-related changes to tumor necrosis factor receptors affect neuron survival in the presence of beta-amyloid

Inflammation including local accumulations of tumor necrosis factor alpha (TNF-alpha) is a part of Alzheimer's disease pathology and may exacerbate age-related neurodegeneration. Most studies on TNF-alpha and TNF neuronal receptors are conducted by using embryonic neurons. Few studies consider age-related deficits that may occur in neurons. Age-related changes in susceptibility to TNF-alpha through TNF receptor 1 (TNFR1) and receptor 2 (TNFR2) expression could increase susceptibility to beta-amyloid (1-42, Abeta42). Evidence is conflicting about which receptor mediates survival and/or apoptosis. We determined how aging affects receptor expression in cultured adult rat cortical neurons. Old neurons were more susceptible to Abeta42 toxicity than middle-aged neurons, and the addition of TNF-alpha was neuroprotective in middle-aged neurons, but exacerbated the toxicity from Abeta42 in old neurons. These pathologic and protective responses in old and middle-aged neurons, respectively, correlated with higher starting TNFR1 and TNFR2 mRNA levels in old vs. middle-aged neurons. Middle-aged neurons treated with TNF-alpha plus Abeta42 did not show an increase in either TNFR1 or TNFR2 mRNA, but old neurons showed an up-regulation in TNFR2 mRNA and not TNFR1 mRNA. Despite these mRNA changes, surface immunoreactivity of both TNFR1 and TNFR2 increased with the dose of TNF-alpha in middle-aged neurons. However, middle-aged neurons treated with TNF-alpha plus Abeta42 showed an up-regulation in both TNFR1 and TNFR2 surface expression, whereas old neurons failed to up-regulate surface expression of either receptor. These findings support the hypothesis that age-related changes in TNF-alpha surface receptor expression contribute to the neuronal loss associated with inflammation in Alzheimer's disease.

Parenchymal and vascular Abeta-deposition and its effects on the degeneration of neurons and cognition in Alzheimer's disease

The deposition of the amyloid beta-protein (Abeta) is one of the pathological hallmarks of Alzheimer's disease (AD). Abeta-deposits show the morphology of senile plaques and cerebral amyloid angiopathy (CAA). Senile plaques and vascular Abeta-deposits occur first in neocorti-cal areas. Then, they expand hierarchically into further brain regions. The distribution of Abeta plaques throughout the entire brain, thereby correlates with the clinical status of the patients. Imaging techniques for Abeta make use of the hierarchical distribution of Abeta to distinguish AD patients from non-AD patients. However, pathology seen in AD patients represents a late stage of a pathological process starting 10-30 years earlier in cognitively normal individuals. In addition to the fibrillar amyloid of senile plaques, oligomeric and monomeric Abeta is found in the brain. Recent studies revealed that oligomeric Abeta is presumably the most toxic Abeta-aggregate, which interacts with glutamatergic synapses. In doing so, dendrites are presumed to be the primary target for Abeta-toxicity. In addition, vascular Abeta-deposits can lead to capillary occlusion and blood flow disturbances presumably contributing to the alteration of neurons in addition to the direct neurotoxic effects of Abeta. All these findings point to an important role of Abeta and its aggregates in the neurodegenerative process of AD. Since there is already significant neuron loss in AD patients, treatment strategies aimed at reducing the amyloid load will presumably not cure the symptoms of dementia but they may stop disease progression. Therefore, it seems to be necessary to protect the brain from Abeta-toxicity already in stages of the disease with minor neuron loss before the onset of cognitive symptoms.

ADAPT Research Group, Martin BK, Szekely C, Brandt J, Piantadosi S, Breitner JCS, Craft S, Evans D, Green R, Mullan M. Cognitive function over time in the Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT): results of a randomized, controlled trial of naproxen and celecoxib

BACKGROUND

Observational studies have shown reduced risk of Alzheimer dementia in users of nonsteroidal anti-inflammatory drugs.

OBJECTIVE

To evaluate the effects of naproxen sodium and celecoxib on cognitive function in older adults.

DESIGN

Randomized, double-masked chemoprevention trial.

SETTING

Six US memory clinics.

PARTICIPANTS

Men and women aged 70 years and older with a family history of Alzheimer disease; 2117 of 2528 enrolled had follow-up cognitive assessment.

INTERVENTIONS

Celecoxib (200 mg twice daily), naproxen sodium (220 mg twice daily), or placebo, randomly allocated in a ratio of 1:1:1.5, respectively.

MAIN OUTCOME MEASURES

Seven tests of cognitive function and a global summary score measured annually.

RESULTS

Longitudinal analyses showed lower global summary scores over time for naproxen compared with placebo (- 0.05 SDs; P = .02) and lower scores on the Modified Mini-Mental State Examination over time for both treatment groups compared with placebo (- 0.33 points for celecoxib [P = .04] and - 0.36 points for naproxen [P = .02]). Restriction of analyses to measures collected from persons without dementia attenuated the treatment group differences. Analyses limited to measures obtained while participants were being issued study drugs produced results similar to the intention-to-treat analyses.

CONCLUSIONS

Use of naproxen or celecoxib did not improve cognitive function. There was weak evidence for a detrimental effect of naproxen.

No advantage of A beta 42-lowering NSAIDs for prevention of Alzheimer dementia in six pooled cohort studies

INTRODUCTION

Observational studies show reduced incidence of Alzheimer dementia (AD) in users of nonsteroidal anti-inflammatory drugs (NSAIDs). One hypothesis holds that the subset of NSAIDs known as selective A beta(42)-lowering agents (SALAs) is responsible for this apparent reduction in AD risk.

METHODS

We pooled individual-level data from six prospective studies to obtain a sufficient sample to examine AD risk in users of SALA vs non-SALA NSAIDs.

RESULTS

Of 13,499 initially dementia-free participants (70,863 person-years), 820 developed incident AD. Users of NSAIDs (29.6%) showed reduced risk of AD (adjusted hazard ratio [aHR] 0.77, 95% CI 0.65-0.91). The point estimates were similar for SALAs (aHR 0.87, CI 0.72-1.04) and non-SALAs (aHR 0.75, CI 0.56-1.01). Because 573 NSAID users (14.5%) reported taking both a SALA and non-SALA, we examined their use alone and in combination. Resulting aHRs were 0.82 (CI 0.67-0.99) for SALA only, 0.60 (CI 0.40-0.90) for non-SALA only, and 0.87 (CI 0.57-1.33) for both NSAIDs (Wald test for differences, p = 0.32). The 40.7% of participants who used aspirin also showed reduced risk of AD, even when they used no other NSAIDs (aHR 0.78, CI 0.66-0.92). By contrast, there was no association with use of acetaminophen (aHR 0.93, CI 0.76-1.13).

CONCLUSIONS

In this pooled dataset, nonsteroidal anti-inflammatory drug (NSAID) use reduced the risk of Alzheimer dementia (AD). However, there was no apparent advantage in AD risk reduction for the subset of NSAIDs shown to selectively lower A beta(42), suggesting that all conventional NSAIDs including aspirin have a similar protective effect in humans.

Neuroinflammatory response to lipopolysaccharide is exacerbated in mice genetically deficient in cyclooxygenase-2

Background

Cyclooxygenases (COX) -1 and -2 are key mediators of the inflammatory response in the central nervous system. Since COX-2 is inducible by inflammatory stimuli, it has been traditionally considered as the most appropriate target for anti-inflammatory drugs. However, the specific roles of COX-1 and COX-2 in modulating a neuroinflammatory response are unclear. Recently, we demonstrated that COX-1 deficient mice show decreased neuroinflammatory response and neuronal damage in response to lipopolysaccharide (LPS).

Methods

In this study, we investigated the role of COX-2 in the neuroinflammatory response to intracerebroventricular-injected LPS (5 μg), a model of direct activation of innate immunity, using COX-2 deficient (COX-2^-/-) and wild type (COX-2^+/+) mice, as well as COX-2^+/+ mice pretreated for 6 weeks with celecoxib, a COX-2 selective inhibitor.

Results

Twenty-four hours after LPS injection, COX-2^-/- mice showed increased neuronal damage, glial cell activation, mRNA and protein expression of markers of inflammation and oxidative stress, such as cytokines, chemokines, iNOS and NADPH oxidase. Brain protein levels of IL-1β, NADPH oxidase subunit p67^phox, and phosphorylated-signal transducer and activator of transcription 3 (STAT3) were higher in COX-2^-/- and in celecoxib-treated mice, compared to COX-2^+/+ mice. The increased neuroinflammatory response in COX-2^-/- mice was likely mediated by the upregulation of STAT3 and suppressor of cytokine signaling 3 (SOCS3).

Conclusion

These results show that inhibiting COX-2 activity can exacerbate the inflammatory response to LPS, possibly by increasing glial cells activation and upregulating the STAT3 and SOCS3 pathways in the brain.

[(18)F]-labeled isoindol-1-one and isoindol-1,3-dione derivatives as potential PET imaging agents for detection of beta-amyloid fibrils

In this study a novel series of isoindol-1-one and isoindol-1,3-dione derivatives for beta-amyloid-specific binding agents is described. Twelve compounds were synthesized and evaluated via a competitive binding assay with [(125)I]TZDM against beta-amyloid 1-42 (Abeta42) aggregates. Two new [(18)F]-labeled isoindole derivatives were synthesized and evaluated as potential beta-amyloid imaging probes based on the in vivo pharmacokinetic profiles. The preliminary results suggest that these [(18)F]18b and [(18)F]18c are promising positron emission tomography (PET) imaging probes for studying accumulation of Abeta fibrils in the brains of Alzheimer's disease (AD) patients.

Protective effects of NSAIDs on the development of Alzheimer disease

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer disease (AD), but observational studies and trials have offered contradictory results. Prior studies have also been relatively short and small. We examined the effects on AD risk of NSAID use for >5 years and of NSAIDs that suppress formation of A beta (1-42) amyloid in a large health care database.

METHODS

Cases were veterans aged 55 years and older with incident AD using the US Veterans Affairs Health Care system. Matched controls were drawn from the same population. NSAID exposure was categorized into seven time periods: no use, 1 but

RESULTS

We identified 49,349 cases and 196,850 controls. Compared with no NSAID use, the adjusted odds ratios for AD among NSAID users decreased from 0.98 for 5 years of use (0.68-0.85). For users of ibuprofen, it decreased from 1.03 (1.00-1.06) to 0.56 (0.42-0.75). Effects of other NSAID classes and individual NSAIDs were inconsistent. There was no difference between a group of A beta (1-42)-suppressing NSAIDs and others.

DISCUSSION

Long-term nonsteroidal anti-inflammatory drug (NSAID) use was protective against Alzheimer disease. Findings were clearest for ibuprofen. A beta (1-42)-suppressing NSAIDs did not differ from others.

Collapse

Key Words Collapse

MESH Headings

• Age Factors
• Aged
• Alzheimer Disease/drug therapy
• Alzheimer Disease/metabolism
• Alzheimer Disease/prevention & control
• Amyloid beta-Peptides/antagonists & inhibitors
• Amyloid beta-Peptides/metabolism
• Anti-Inflammatory Agents, Non-Steroidal/classification
• Anti-Inflammatory Agents, Non-Steroidal/pharmacology
• Anti-Inflammatory Agents, Non-Steroidal/therapeutic use
• Brain/drug effects
• Brain/metabolism
• Brain/physiopathology
• Case-Control Studies
• Drug Administration Schedule
• Encephalitis/drug therapy
• Encephalitis/metabolism
• Encephalitis/prevention & control
• Female
• Humans
• Ibuprofen/classification
• Ibuprofen/pharmacology
• Ibuprofen/therapeutic use
• Male
• Middle Aged
• Neuroprotective Agents/pharmacology
• Neuroprotective Agents/therapeutic use
• Peptide Fragments/antagonists & inhibitors
• Peptide Fragments/metabolism
• Racial Groups
• Sex Distribution
• Time
• Treatment Outcome

Collapse

Grants

• AR47785 NIAMS NIH HHS
• T32 AR007598 NIAMS NIH HHS
• P30 AG013846 NIA NIH HHS
• P60 AR047785 NIAMS NIH HHS
• AR07598 NIAMS NIH HHS

Collapse

Affiliation(s)

Steven C Vlad Boston University School of Medicine, Clinical Epidemiology Research and Training Unit, 650 Albany St., Suite X200, Boston, MA 02118, USA.
Donald R Miller
Neil W Kowall
David T Felson

Collapse

Collaborators Collapse

Genetic deletion or pharmacological inhibition of cyclooxygenase-1 attenuate lipopolysaccharide-induced inflammatory response and brain injury

Cyclooxygenase (COX) -1 and -2 metabolize arachidonic acid to prostanoids and reactive oxygen species, major players in the neuroinflammatory process. While most reports have focused on the inducible isoform, COX-2, the contribution of COX-1 to the inflammatory response is unclear. In the present study, the contribution of COX-1 in the neuroinflammatory response to intracerebroventricular lipopolysaccharide (LPS) was investigated using COX-1 deficient (COX-1(-/-)) mice or wild-type (COX-1(+/+)) mice pretreated with SC-560, a selective COX-1 inhibitor. Twenty-four hours after lipopolysaccharide (LPS) injection, COX-1(-/-) mice showed decreased protein oxidation and LPS-induced neuronal damage in the hippocampus compared with COX-1(+/+) mice. COX-1(-/-) mice showed a significant reduction of microglial activation, proinflammatory mediators, and expression of COX-2, inducible NOS, and NADPH oxidase. The transcriptional down-regulation of cytokines and other inflammatory markers in COX-1(-/-) mice was mediated by a reduced activation of NF-kappaB and signal transducer and activator of transcription 3. Administration of SC-560 prior to LPS injection also attenuated the neuroinflammatory response by decreasing brain levels of prostaglandin (PG)E(2), PGD(2), PGF(2alpha), and thromboxane B(2), as well as the expression of proinflammatory cytokines and chemokine. These findings suggest that COX-1 plays a previously unrecognized role in neuroinflammatory damage.

Alzheimer's and non-alzheimer's dementia: a critical review of pharmacological and nonpharmacological strategies

OBJECTIVE

Dementia is an age-related progressive neurodegenerative disorder afflicting about 5% of the world's population, and it is expected to grow dramatically in the future keeping in view our ageing society. Currently available medications appear to be able to produce moderate symptomatic benefits but do not to stop disease progression. In this article, the management of the disorder, including the currently available drugs as well as psychosocial strategies, is discussed.

METHODS

A computerized search on Pubmed from 1980 to 2006 was carried out and all articles evaluated and graded on NICE guidelines.

RESULTS AND CONCLUSIONS

Currently evaluated and accepted medications only bring about a reduction in the deteriorating course. A combination of pharmacotherapy and psychosocial management is the need of the hour.

Pharmacological attenuation of electroconvulsive therapy--induced cognitive deficits: theoretical background and clinical findings

Electroconvulsive therapy (ECT) is an effective treatment for depression and other psychiatric disorders. However, the practice of ECT is limited by memory and nonmemory cognitive adverse effects. Technical strategies such as a preference for unilateralover bilateral ECT and low-dose over high-dose stimulation reduce these cognitive adverse effects but may also be associated with lesser treatment efficacy or slower treatment response. This article therefore reviews the use of psychopharmacological agents in the attenuation of ECT-induced cognitive deficits with 2 objectives: the identification of implicated mechanisms and the identification of putative efficacy in both animal and human studies. Drugs examined include N-methyl-d-aspartate receptor antagonists, cyclooxygenase inhibitors, calcium channel blockers, cholinesterase inhibitors, glucocorticoid receptor antagonists, thyroid hormones, opioid antagonists, NO donors, nootropic agents, and other medications. Although the clinical data at present are sparse and inconsistent, many recently opened lines of research improve our understanding of the mechanisms involved as well as suggest possible avenues for the testing of new treatments with the potential to attenuate the cognitive adverse effects of ECT.

The role of interleukin-1 in neuroinflammation and Alzheimer disease: an evolving perspective

Elevation of the proinflammatory cytokine Interleukin-1 (IL-1) is an integral part of the local tissue reaction to central nervous system (CNS) insult. The discovery of increased IL-1 levels in patients following acute injury and in chronic neurodegenerative disease laid the foundation for two decades of research that has provided important details regarding IL-1's biology and function in the CNS. IL-1 elevation is now recognized as a critical component of the brain's patterned response to insults, termed neuroinflammation, and of leukocyte recruitment to the CNS. These processes are believed to underlie IL-1's function in the setting of acute brain injury, where it has been ascribed potential roles in repair as well as in exacerbation of damage. Explorations of IL-1's role in chronic neurodegenerative disease have mainly focused on Alzheimer disease (AD), where indirect evidence has implicated it in disease pathogenesis. However, recent observations in animal models challenge earlier assumptions that IL-1 elevation and resulting neuroinflammatory processes play a purely detrimental role in AD, and prompt a need for new characterizations of IL-1 function. Potentially adaptive functions of IL-1 elevation in AD warrant further mechanistic studies, and provide evidence that enhancement of these effects may help to alleviate the pathologic burden of disease.

Targeting cytokine expression in glial cells by cellular delivery of an NF-kappaB decoy

Inhibition of nuclear factor (NF)-kappaB has emerged as an important strategy for design of anti-inflammatory therapies. In neurodegenerative disorders like Alzheimer's disease, inflammatory reactions mediated by glial cells are believed to promote disease progression. Here, we report that uptake of a double-stranded oligonucleotide NF-kappaB decoy in rat primary glial cells is clearly facilitated by noncovalent binding to a cell-penetrating peptide, transportan 10, via a complementary peptide nucleic acid (PNA) sequence. Fluorescently labeled oligonucleotide decoy was detected in the cells within 1 h only when cells were incubated with the decoy in the presence of cell-penetrating peptide. Cellular delivery of the decoy also inhibited effects induced by a neurotoxic fragment of the Alzheimer beta-amyloid peptide in the presence of the inflammatory cytokine interleukin (IL)-1beta. Pretreatment of the cells with the complex formed by the decoy and the cell-penetrating peptide-PNA resulted in 80% and 50% inhibition of the NF-kappaB binding activity and IL-6 mRNA expression, respectively.

No effect of one-year treatment with indomethacin on Alzheimer's disease progression: a randomized controlled trial

Background

The objective of this study was to determine whether treatment with the nonselective nonsteroidal anti-inflammatory drug (NSAID) indomethacin slows cognitive decline in patients with Alzheimer's disease (AD).

Methodology/Principal Findings

This double-blind, randomized, placebo-controlled trial was conducted between May 2000 and September 2005 in two hospitals in the Netherlands. 51 patients with mild to moderate AD were enrolled into the study. Patients received 100 mg indomethacin or placebo daily for 12 months. Additionally, all patients received omeprazole. The primary outcome measure was the change from baseline after one year of treatment on the cognitive subscale of the AD Assessment Scale (ADAS-cog). Secondary outcome measures included the Mini-Mental State Examination, the Clinician's Interview Based Impression of Change with caregiver input, the noncognitive subscale of the ADAS, the Neuropsychiatric Inventory, and the Interview for Deterioration in Daily life in Dementia. Considerable recruitment problems of participants were encountered, leading to an underpowered study. In the placebo group, 19 out of 25 patients completed the study, and 19 out of 26 patients in the indomethacin group. The deterioration on the ADAS-cog was less in the indomethacin group (7.8±7.6), than in the placebo group (9.3±10.0). This difference (1.5 points; CI −4.5–7.5) was not statistically significant, and neither were any of the secondary outcome measures.

Conclusions/Significance

The results of this study are inconclusive with respect to the hypothesis that indomethacin slows the progression of AD.

Trial Registration

ClinicalTrials.gov NCT00432081

NSAID use and dementia risk in the Cardiovascular Health Study: role of APOE and NSAID type

BACKGROUND

Epidemiologic and laboratory studies suggest that nonsteroidal antiinflammatory drugs (NSAIDs) reduce risk of Alzheimer disease (AD). We therefore investigated the association between use of NSAIDs, aspirin, and the non-NSAID analgesic acetaminophen with incidence of dementia and AD.

METHODS

Participants in the Cardiovascular Health Cognition Study included 3,229 individuals aged 65 or older, free of dementia at baseline, with information on medication use. We used Cox proportional hazards regression to estimate the association of medication use with incident all-cause dementia, AD, and vascular dementia (VaD). Additional analyses considered the NSAID-AD relationship as a function of age, presence of at least one epsilon 4 allele at APOE, race, and individual NSAIDs' reported ability to reduce production of the amyloid-beta peptide variant A beta(42).

RESULTS

Use of NSAIDs was associated with a lower risk of dementia (adjusted hazard ratio or aHR 0.76, 95% CI or CI 0.60-0.96) and, in particular, AD (aHR 0.63, CI 0.45-0.88), but not VaD (aHR 0.92, CI 0.65-1.28). No similar trends were observed with acetaminophen (aHR 0.99, CI 0.79-1.24). Closer examination suggested AD risk reduction with NSAIDs only in participants having an APOE epsilon 4 allele (aHR 0.34, CI 0.18-0.65; aHR for others 0.88, CI 0.59-1.32). There was no advantage in AD risk reduction with NSAIDs reported to selectively reduce A beta(42).

CONCLUSIONS

Results were consistent with previous cohort studies showing reduced risk of AD in NSAID users, but this association was found only in those with an APOE epsilon 4 allele, and there was no advantage for A beta(42)-lowering NSAIDs.

Anti-inflammatory and immune therapy for Alzheimer's disease: current status and future directions

From the initial characterizations of inflammatory responses in Alzheimer's disease (AD) affected brains, namely the demonstration of activated microglia and reactive astrocytes, complement system activation, increased production of proinflammatory cytokines, and evidence for microglial-produced neurotoxins, there was hope that reducing inflammation might be a feasible treatment for this memory-robbing disease. This hope was supported by a number of epidemiology studies demonstrating that patients who took non-steroidal anti-inflammatory drugs had significantly lower risk of developing AD. However, clinical trials of anti-inflammatories have not shown effectiveness, and in recent years, the concept of immune therapy has become a treatment option as animal studies and clinical trials with Abeta vaccines have demonstrated enhanced amyloid removal through stimulation of microglial phagocytosis.This review will examine the current status of whether inhibiting inflammation is a valid therapeutic target for treating AD; what lessons have come from the clinical trials; what new pathways and classes of agents are being considered; and how this field of research can progress towards new therapeutics. We will examine a number of agents that have shown effectiveness in reducing inflammation amongst other demonstrated mechanisms of action. The major focus of much AD drug discovery has been in identifying agents that have anti-amyloid properties; however, a number of these agents were first identified for their anti-inflammatory properties. As drug development and clinical testing is a costly and lengthy endeavor, sound justification of new therapeutic targets is required. Possible future directions for AD anti-inflammatory or immune clearance therapy will be discussed based on recent experimental data.

1-(3',4'-Dichloro-2-fluoro[1,1'-biphenyl]-4-yl)-cyclopropanecarboxylic acid (CHF5074), a novel gamma-secretase modulator, reduces brain beta-amyloid pathology in a transgenic mouse model of Alzheimer's disease without causing peripheral toxicity

Some nonsteroidal anti-inflammatory drugs has been shown to allosterically modulate the activity of gamma-secretase, the enzymatic complex responsible for the formation of beta-amyloid (Abeta). 1-(3',4'-Dichloro-2-fluoro[1,1'-biphenyl]-4-yl)-cyclopropanecarboxylic acid (CHF5074) is a new gamma-secretase modulator, devoid of anticyclooxygenase (COX) and Notch-interfering activities in vitro. We evaluated the effects of chronic CHF5074 treatment on brain Abeta pathology in Tg2576 transgenic mice. Twenty-eight animals of 9.5 to 10.5 months of age received CHF5074-medicated diet (375 ppm) or standard diet for 17 weeks. Compared with controls, CHF5074 treatment significantly reduced the area occupied by plaques and the number of plaques in cortex (-52.2 +/- 5.6%, p = 0.0003 and -48.9 +/- 6.6%, p = 0.0004, respectively) and hippocampus (-76.7 +/- 6.4%, p = 0.004 and -66.2 +/- 10.3%, p = 0.037, respectively). Biochemical analysis confirmed the histopathological measures, with CHF5074-treated animals showing reduced total brain Abeta40 (-49.2 +/- 9.2%, p = 0.017) and Abeta42 (-43.5 +/- 9.7%, p = 0.027) levels. In a human neuroglioma cell line expressing Swedish mutated form of amyloid precursor protein (H4swe), CHF5074 reduced Abeta42 and Abeta40 secretion, with an IC50 of 3.6 and 18.4 microM, respectively, values consistent with those measured in the brain of the CHF5074-treated Tg2576 mice (6.4 +/- 0.4 microM). At 5 microM, no effects were observed on Notch intracellular cleavage in human embryonic kidney 293swe cells. CHF5074 was well tolerated by Tg2576 mice. No abnormal findings were observed upon histopathological examination of the gastrointestinal tract, indicating the absence of COX-related toxicity. Semiquantitative histochemical evaluation of goblet cells in the ileum of vehicle- and CHF5074-treated animals yielded similar results, suggesting no effects on Notch pathway. CHF5074 is therefore a promising therapeutic agent for Alzheimer's disease.

Prevention of Alzheimer's disease

The already considerable public health burden of Alzheimer's disease will likely worsen as populations around the world age. As a result, there is considerable motivation to develop effective strategies for preventing the disease. A wide variety of such strategies are under investigation and include pharmaceuticals, nutriceuticals, diet, physical activity and cognitive activity. We review here the most promising candidates and the epidemiologic evidence for their efficacy. Although none of these have yet to be definitively shown to prevent Alzheimer's disease, further research should help to clarify what role they may play in reducing the burden of this disease.

Alpha7 nicotinic acetylcholine receptor: a link between inflammation and neurodegeneration

Alzheimer's disease (AD) is the leading cause of dementia affecting over 25 million people worldwide. Classical studies focused on the description and characterization of the pathological hallmarks found in AD patients including the neurofibrillary tangles and the amyloid plaques. Current strategies focus on the etiology of these hallmarks and the different mechanisms contributing to neurodegeneration. Among them, recent studies reveal the close interplay between the immunological and the neurodegenerative processes. This article examines the implications of the alpha7 nicotinic acetylcholine receptor (alpha7nAChR) as a critical link between inflammation and neurodegeneration in AD. Alpha7nAChRs are not only expressed in neurons but also in Glia cells where they can modulate the immunological responses contributing to AD. Successful therapeutic strategies against AD should consider the connections between inflammation and neurodegeneration. Among them, alpha7nAChR may represent a pharmacological target to control these two mechanisms during the pathogenesis of neurodegenerative and behavioral disorders.

Neuroinflammation: implications for the pathogenesis and molecular diagnosis of Alzheimer's disease

During the past few years, an increasing set of evidence has supported the major role of deregulation of the interaction patterns between glial cells and neurons in the pathway toward neuronal degeneration. Neurons and glial cells, together with brain vessels, constitute an integrated system for brain function. Inflammation is a process related with the onset of several neurodegenerative disorders, including Alzheimer's disease (AD). Several hypotheses have been postulated to explain the pathogenesis of AD, but none provides insight into the early events that trigger metabolic and cellular alterations in neuronal degeneration. The amyloid hypothesis was sustained on the basis that Abeta-peptide deposition into senile plaques is responsible for neurodegeneration. However, recent findings point to Abeta oligomers as responsible for synaptic impairment in neuronal degeneration. Amyloid is only one among many other major factors affecting the quality of neuronal cells. Another explanation derives from the tau hypothesis, supported by the observations that tau hyperphosphorylations constitute a common feature of most of the altered signaling pathways in degenerating neurons. Altered tau patterns have been detected in the cerebrospinal fluids of AD patients, and a close correlation was observed between the levels of hyperphosphorylated tau isoforms and the degree of cognitive impairment. On the other hand, the anomalous effects of cytokines and trophic factors share in common the activation of tau hyperphosphorylation patterns. In this context, a neuroimmunological approach to AD becomes relevant. When glial cells that normally provide neurotrophic factors essential for neurogenesis are activated by a set of stressing events, they overproduce cytokines and NGF, thus triggering altered signaling patterns in the etiopathogenesis of AD. A solid set of discoveries has strengthened the idea that altered patterns in the glia-neuron interactions constitute early molecular events within the cascade of cellular signals that lead to neurodegeneration in AD. A direct correlation has been established between the Abeta-induced neurodegeneration and cytokine production and its subsequent release. In effect, neuroinflammation is responsible for an abnormal secretion of proinflammatory cytokines that trigger signaling pathways that activate brain tau hyperphosphorylation in residues that are not modified under normal physiological conditions. Other cytokines such as IL-3 and TNF-alpha seem to display neuroprotective activities. Elucidation of the events that control the transitions from neuroprotection to neurodegeneration should be a critical point toward elucidation of AD pathogenesis.

Multifunctional neuroprotective drugs targeting monoamine oxidase inhibition, iron chelation, adenosine receptors, and cholinergic and glutamatergic action for neurodegenerative diseases

A new paradigm is emerging in the targeting of multiple disease aetiologies that collectively lead to neurodegenerative disorders such as Parkinson's disease, Alzheimer's disease, post-stroke neurodegeneration and others. This paradigm challenges the widely held assumption that 'silver bullet' agents are superior to 'dirty drugs' when it comes to drug therapy. Accumulating evidence in the literature suggests that many neurodegenerative diseases have multiple mechanisms in their aetiologies, thus suggesting that a drug with at least two mechanisms of action targeted at multiple aetiologies of the same disease may offer more therapeutic benefit in certain disorders compared with a drug that only targets one disease aetiology. This review offers a synopsis of therapeutic strategies and novel investigative drugs developed in the authors' own and other laboratories that modulate multiple disease targets associated with neurodegenerative diseases.

Pharmacotherapy of Alzheimer disease

OBJECTIVE

To systematically review published clinical trials of the pharmacotherapy of Alzheimer disease (AD).

METHOD

We searched MEDLINE for published English-language medical literature, using Alzheimer disease and treatment as key words. No other search engine was used. Our review focused on randomized clinical trials (RCTs) and corresponding metaanalyses.

RESULTS

Although there are many RCTs for the treatment of mild cognitive impairment (MCI), none have been successful in their primary analysis. The cholinesterase inhibitors donepezil, rivastigmine, and galantamine have demonstrated efficacy in 3- to 12-month placebo-controlled RCTs assessing cognitive, functional, behavioural, and global outcomes in patients with mildly to moderately severe AD. Recent data from patients with severe stages of AD demonstrate the efficacy of donepezil on cognitive and functional measures but not on behaviour. The N-methyl-D-aspartate receptor antagonist memantine has been demonstrated to be effective in 6-month, placebo-controlled RCTs of 6 months duration assessing cognitive, functional, and global outcomes of inpatients with moderate-to-severe AD (defined as a Mini Mental State Examination score below 20). Post hoc analyses have demonstrated a benefit in regard to agitation and (or) aggression, but this needs to be confirmed in a prospective RCT across Canada. Disease-modifying treatments are being tested in mild stages of AD in 18-month RCTs with cognitive and global outcomes as primary efficacy outcomes, primarily with drugs reducing amyloid synthesis or aggregation. Successful treatment in mild stages of AD could lead to RCTs in MCI and, possibly, in genetically high-risk asymptomatic individuals.

CONCLUSION

The significant advances in the symptomatic pharmacotherapy of AD may be followed by disease-modification treatments.

DP-155, a lecithin derivative of indomethacin, is a novel nonsteroidal antiinflammatory drug for analgesia and Alzheimer's disease therapy

DP-155 is a lipid prodrug of indomethacin that comprises the latter conjugated to lecithin at position sn-2 via a 5-carbon length linker. It is cleaved by phospholipase A2 (PLA)(2) to a greater extent than similar compounds with linkers of 2, 3, and 4 carbons. Indomethacin is the principal metabolite of DP-155 in rat serum and, after DP-155 oral administration, the half-life of the metabolite was 22 and 93 h in serum and brain, respectively, compared to 10 and 24 h following indomethacin administration. The brain to serum ratio was 3.5 times higher for DP-155 than for indomethacin. In vitro studies demonstrated that DP-155 is a selective cyclooxygenase (COX)-2 inhibitor. After it is cleaved, its indomethacin derivative nonselectively inhibits both COX-1 and -2. DP-155 showed a better toxicity profile probably due to the sustained, low serum levels and reduced maximal concentration of its indomethacin metabolite. DP-155 did not produce gastric toxicity at the highest acute dose tested (0.28 mmol/kg), while indomethacin caused gastric ulcers at a dose 33-fold lower. Furthermore, after repeated oral dosing, gastrointestinal and renal toxicity was lower (10- and 5-fold, respectively) and delayed with DP-155 compared to indomethacin. In addition to reduced toxicity, DP-155 had similar ameliorative effects to indomethacin in antipyretic and analgesia models. Moreover, DP-155 and indomethacin were equally efficacious in reducing levels of amyloid ss (Ass)42 in transgenic Alzheimer's disease mouse (Tg2576) brains as well as reducing Ass42 intracellular uptake, neurodegeneration, and inflammation in an in vitro AD model. The relatively high brain levels of indomethacin after DP-155 administration explain the equal efficacy of DP-155 despite its low systemic blood concentrations. Compared to indomethacin, the favored safety profile and equal efficacy of DP-155 establish the compound as a potential candidate for chronic use to treat AD-related pathology and for analgesia.

Alzheimer's disease and mild cognitive impairment

As our society ages, age-related diseases assume increasing prominence as both personal and public health concerns. Disorders of cognition are particularly important in both regards, and Alzheimer's disease is by far the most common cause of dementia of aging. In 2000, the prevalence of Alzheimer's disease in the United States was estimated to be 4.5 million individuals, and this number has been projected to increase to 14 million by 2050. Although not an inevitable consequence of aging, these numbers speak to the dramatic scope of its impact. This article focuses on Alzheimer's disease and the milder degrees of cognitive impairment that may precede the clinical diagnosis of probable Alzheimer's disease, such as mild cognitive impairment.

Altered expression of COX-2 in subdivisions of the hippocampus during aging and in Alzheimer's disease: the Hisayama Study

BACKGROUND

It has been reported that nonsteroidal anti-inflammatory drugs may delay the onset of Alzheimer's disease (AD). Since nonsteroidal anti-inflammatory drugs inhibit cyclooxygenase (COX), COX-2, an inducible form of COX, may be involved in the pathology of AD in association with the arachidonic acid cascade. In addition, it has been suggested that alterations in the balance of polyunsaturated fatty acids are associated with brain dysfunctions such as neurodegerative pathologies of the aging brain.

METHOD

To explore COX-2 expression in the hippocampus, we analyzed 45 consecutive autopsy subjects without dementia and 25 AD patients derived from the town of Hisayama, Japan.

RESULTS

The neuronal expression of COX-2 in the CA3 subdivision of the hippocampus, subiculum, entorhinal cortex and transentorhinal cortex were consistently observed in both nondemented and AD brains, and COX-2 immunoreactivity correlated with age in nondemented brains. In AD patients, neurons of CA1 exhibited increased COX-2 immunoreactivity which correlated with the severity of AD pathology. This correlation was not apparent in nondemented subjects.

CONCLUSION

These results suggest that COX-2 expression may be differentially regulated among subdivisions of the hippocampus and that elevated COX-2 expression in the CA1 of AD brains may be associated with AD pathology and thus cognitive dysfunction.

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 Aβ42 in cell culture and animal models, and that the effect of NSAIDs on Aβ42 is independent of the inhibition of cyclooxygenase by these compounds. Since Aβ42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower Aβ42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil) as a selective Aβ42 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 Aβ 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 Aβ 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 Aβ 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 Aβ 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 Aβ42 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.

Hematopoietic prostaglandin D synthase and DP1 receptor are selectively upregulated in microglia and astrocytes within senile plaques from human patients and in a mouse model of Alzheimer disease

Prostaglandin (PG) D2 is produced in activated microglia by the action of hematopoietic PGD synthase (HPGDS) and plays important roles in neuroinflammation. Because the fact that neuroinflammation accelerates progression of Alzheimer disease (AD) has been documented, we investigated whether PGD2 is also involved in the pathology of AD. Here, we report that the level of the mRNA of the receptor for PGD2 (DP1) was increased in AD brains compared with the level in non-AD brains. Immunocytochemical analysis showed HPGDS expression to be localized in the microglia surrounding senile plaques. In situ hybridization studies revealed that DP1 mRNA was specifically localized in microglia and reactive astrocytes within senile plaques of AD brains. In the brain of Tg2576 mice, a model of AD, HPGDS and DP1 proteins were mainly localized immunocytochemically in microglia and astrocytes in the plaques, and the levels of their mRNAs increased in parallel with amyloid beta deposition. These results indicate that PGD2 may act as a mediator of plaque-associated inflammation in AD brain and may explain the pharmacologic mechanisms underlying the favorable response of patients with AD to nonsteroidal anti-inflammatory drugs.

Cholesterol independent effect of LXR agonist TO-901317 on gamma-secretase

The balance of intracellular cholesterol has proven to be critical to the production of beta-amyloid (A beta). Reducing cholesterol in vitro leads to decreased production of A beta, whereas an increase in cellular cholesterol induces A beta production. Liver X Receptor (LXR) agonists are known to increase cholesterol efflux from cells, but there are conflicting reports as to the effects of these agonists on A beta production. We therefore examined the effects of efflux-inducing agents on A beta production in vitro. We used methyl-beta-cyclodextrin and an LXR agonist (TO-901317) to induce cholesterol efflux and studied the resulting A beta production in a stable amyloid precursor protein (APP) -transfected cell line. When cholesterol efflux was induced with methyl-beta-cyclodextrin there was a >60% decrease in A beta(40) and A beta(42) production. However, while activation of LXR using TO-901317-induced cholesterol efflux in the presence of a cholesterol acceptor, no changes in A beta levels were recorded. When cells were incubated with TO-901317 above the concentration required for maximal cholesterol efflux, there was a 150% increase in A beta(42) levels. The absence of a cholesterol acceptor from the culture media (preventing cholesterol efflux) did not blunt this increase in A beta(42), suggesting that the effects of TO-901317 on A beta(42) are efflux independent. These results were confirmed in APP stably transfected human H4 cells, which revealed in addition to a 200% increase in A beta(42) levels, a concomitant 80% reduction in A beta(38). A cell-free gamma-secretase assay confirmed that TO-901317 can directly alter gamma-secretase activity. These data demonstrate that TO-901317 can directly modulate the site of cleavage of APP by gamma-secretase in vitro.

Low dose aspirin and cognitive function in the women's health study cognitive cohort

OBJECTIVE

To determine whether low dose aspirin protects women aged 65 or more against cognitive decline.

DESIGN

Cohort study within both arms of the women's health study, a randomised, double blind, placebo controlled trial of low dose aspirin for the primary prevention of cardiovascular disease and cancer, 1992-5.

SETTING

Women's health study, 1998-2004.

PARTICIPANTS

6377 women aged 65 or more.

INTERVENTIONS

Low dose aspirin (100 mg on alternate days) or placebo for a mean of 9.6 years.

MAIN OUTCOME MEASURES

Women had three cognitive assessments at two year intervals by telephone. The battery to assess cognition included five tests measuring general cognition, verbal memory, and category fluency. The primary prespecified outcome was a global score, averaging performance across all tests. The key secondary outcome was a verbal memory score, averaging performance on four measures of verbal memory.

RESULTS

At the initial assessment (mean 5.6 years after randomisation) cognitive performance in the aspirin group was similar to that of the placebo group (mean difference in global score -0.01, 95% confidence interval -0.04 to 0.02). Mean decline in the global score from the first to the final cognitive assessment was also similar in the aspirin compared with placebo groups (mean difference 0.01, -0.02 to 0.04). The risk of substantial decline (in the worst 10th centile of decline) was also comparable between the groups (relative risk 0.92, 0.77 to 1.10). Findings were similar for verbal memory; however, a 20% lower risk was observed for decline in category fluency with aspirin (relative risk 0.80, 0.67 to 0.97).

CONCLUSION

Long term use of low dose aspirin does not provide overall benefits for cognition among generally healthy women aged 65 or more.

Long-term efficacy and safety of celecoxib in Alzheimer's disease

BACKGROUND/AIMS

Cyclooxygenase-2 (COX-2) may play an important role in the neuropathology of Alzheimer's disease (AD). The efficacy and safety of celecoxib (200 mg bid), a COX-2 selective inhibitor, were assessed in patients > or =50 years with established mild-to-moderate AD to determine whether treatment was effective in retarding deterioration of cognitive function.

METHODS

This was a 52-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. The primary efficacy end points were the change from baseline to week 52 in the Alzheimer's Disease Assessment Scale-Cognitive Behavior (ADAS-cog) composite score and the week 52 Clinician's Interview-Based Impression of Change Plus (CIBIC+).

RESULTS

At 52 weeks, change in ADAS-cog scores from baseline was similar for placebo and celecoxib 200 mg bid groups (5.00 and 4.39, respectively). CIBIC+ scores were also similar (4.83 and 4.92). Two extension studies were conducted but were terminated early based on these efficacy results. Safety data from all 3 studies indicated that celecoxib was generally well-tolerated.

CONCLUSION

Celecoxib 200 mg bid did not slow the progression of AD in this study, and the occurrence of adverse events was as expected for an elderly population with a complex chronic medical condition.

Alzheimer's disease: progress in the development of anti-amyloid disease-modifying therapies

The amyloid hypothesis--the leading mechanistic theory of Alzheimer's disease--states that an imbalance in production or clearance of amyloid beta (Abeta) results in accumulation of Abeta and triggers a cascade of events leading to neurodegeneration and dementia. The number of persons with Alzheimer's disease is expected to triple by mid-century. If steps are not taken to delay the onset or slow the progression of Alzheimer's disease, the economic and personal tolls will be immense. Different classes of potentially disease-modifying treatments that interrupt early pathological events (ie, decreasing production or aggregation of Abeta or increasing its clearance) and potentially prevent downstream events are in phase II or III clinical studies. These include immunotherapies; secretase inhibitors; selective Abeta42-lowering agents; statins; anti-Abeta aggregation agents; peroxisome proliferator-activated receptor-gamma agonists; and others. Safety and serious adverse events have been a concern with immunotherapy and gamma-secretase inhibitors, though both continue in clinical trials. Anti-amyloid disease-modifying drugs that seem promising and have reached phase III clinical trials include those that selectively target Abeta42 production (eg, tarenflurbil), enhance the activity of alpha-secretase (eg, statins), and block Abeta aggregation (eg, transiposate).