Rofecoxib: no effect on Alzheimer's disease in a 1-year, randomized, blinded, controlled study

Mechanisms underlying inflammation in neurodegeneration

Inflammation is associated with many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. In this Review, we discuss inducers, sensors, transducers, and effectors of neuroinflammation that contribute to neuronal dysfunction and death. Although inducers of inflammation may be generated in a disease-specific manner, there is evidence for a remarkable convergence in the mechanisms responsible for the sensing, transduction, and amplification of inflammatory processes that result in the production of neurotoxic mediators. A major unanswered question is whether pharmacological inhibition of inflammation pathways will be able to safely reverse or slow the course of disease.

An update on the efficacy of non-steroidal anti-inflammatory drugs in Alzheimer's disease

Several epidemiological studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer's disease (AD), especially for patients carrying one or more epsilon4 allele of the apolipoprotein E. The biological mechanism of this protection is not completely understood and may involve inhibition of COX activity, inhibition of beta-amyloid(1-42) (Abeta42) production and aggregation, inhibition of beta-secretase activity, activation of PPAR-gamma or stimulation of neurotrophin synthesis. Unfortunately, long-term, placebo-controlled clinical trials with both non-selective and COX-2 selective NSAIDs in AD patients produced negative results. A secondary prevention study with rofecoxib in patients with mild cognitive impairment and a primary prevention study with naproxen and celecoxib in elderly subjects with a family history of AD were also negative. All these failures have diminished the hope that NSAIDs could be beneficial in the treatment of AD. It is hypothesized that the chronic use of NSAIDs may be beneficial only in the normal brain by inhibiting the production of Abeta42. Once the Abeta deposition process has started, NSAIDs are no longer effective and may even be detrimental because of their inhibiting activity on activated microglia of the AD brain, which mediates Abeta clearance and activates compensatory hippocampal neurogenesis.

Norepinephrine enhances the LPS-induced expression of COX-2 and secretion of PGE2 in primary rat microglia

Background

Recent studies suggest an important role for neurotransmitters as modulators of inflammation. Neuroinflammatory mediators such as cytokines and molecules of the arachidonic acid pathway are generated and released by microglia. The monoamine norepinephrine reduces the production of cytokines by activated microglia in vitro. However, little is known about the effects of norepinephrine on prostanoid synthesis. In the present study, we investigate the role of norepinephrine on cyclooxygenase- (COX-)2 expression/synthesis and prostaglandin (PG)E₂ production in rat primary microglia.

Results

Interestingly, norepinephrine increased COX-2 mRNA, but not protein expression. Norepinephrine strongly enhanced COX-2 expression and PGE₂ production induced by lipopolysaccharide (LPS). This effect is likely to be mediated by β-adrenoreceptors, since β-, but not α-adrenoreceptor agonists produced similar results. Furthermore, β-adrenoreceptor antagonists blocked the enhancement of COX-2 levels induced by norepinephrine and β-adrenoreceptor agonists.

Conclusions

Considering that PGE₂ displays different roles in neuroinflammatory and neurodegenerative disorders, norepinephrine may play an important function in the modulation of these processes in pathophysiological conditions.

Different methods for testing potential cyclooxygenase-1 and cyclooxygenase-2 inhibitors

The need for the development of selective agents, which only inhibit the mainly "harmful" cyclooxygenase-2 (COX-2) while leaving physiological COX-1 mostly unaffected, still remains, especially after the recent issues related to cardiovascular toxicity caused by some COX-2 selective agents. Thus there is still a demand for sensitive and rapid methods to assay for COX-2 selective agents. Among several in vitro testing systems the whole blood assay (WBA) is a well-known method to examine non-steroidal anti-inflammatory drugs (NSAIDs) in view of their potency to inhibit COX activity. This assay has some major advantages over enzyme-based or isolated cell assays. Emergence of artifacts due to cell separation steps is kept to a minimum and substances, even in disproportional high concentrations, can be examined outside the body in a physiological environment resembling most closely the in vivo conditions in living humans, i.e., 37 degrees C, homeostasis, presence of all blood compounds and cell-cell interactions remain intact. While COX-1 human whole blood assays are performed within less than 2 h, for established COX-2 assays one still has to allow for an overnight incubation step before gaining the desired plasma. The aim of the assay described in this chapter is to characterize an optimized human whole blood assay (hWBA). We present a simple, fast and reliable method to examine the capacity of NSAIDs at inhibiting COX-2 activity that can be applied for rapid and routine screening purposes.

Current treatment and recent clinical research in Alzheimer's disease

The transition from either epidemiological observation or the bench to rigorously tested clinical trials in patients with Alzheimer's disease is crucial in understanding which treatments are beneficial to patients. The amyloid hypothesis has undergone scrutiny recently, as many trials aimed at reducing amyloid and plaque have been completed or are in the testing phase. Examples include modulation of the secretases involved in beta amyloid formation, anti-aggregation agents, and immunotherapeutic trials. Other therapies targeting hyperphosphorylated tau and novel targets such as enhancement of mitochondrial function, serotonin receptors, receptor for advanced glycation end products, and nerve growth factor, as well as other strategies, are discussed. A brief review of the current Food and Drug Administration-approved treatments is included.

Do cholinergic therapies have disease-modifying effects in Alzheimer's disease?

The most widely studied and used therapies for Alzheimer's disease (AD) are based on improving cholinergic function in the central nervous system. The acetylcholine-esterase inhibitors (ChEIs) tacrine, donepezil, rivastigmine, and galantamine are all approved, and the latter three are widely used for the symptomatic treatment of mild to moderate AD. Recent research has found that these drugs may act by a variety of other mechanisms including inhibition of butylcholinesterase, regulation of nicotinic receptors, decreasing amyloid precursor protein (APP) and A beta production, and regulation of tau phosphorylation that may influence disease progression. There is also emerging evidence from clinical trials that the ChEIs may delay cognitive and functional progression. Other cholinergic drugs such as muscarinic agonists have been explored, and although they are not approved, there is robust preclinical evidence for a beneficial, perhaps disease-modifying effect. This review summarizes evidence suggesting that these drugs may do more than improve symptoms; they may delay biological progression of the disease.

Pooled analysis of rofecoxib placebo-controlled clinical trial data: lessons for postmarket pharmaceutical safety surveillance

BACKGROUND

In September 2004, rofecoxib was voluntarily withdrawn from the worldwide market. Our objective was to determine whether and when analysis of published and unpublished placebo-controlled trials could have revealed cardiovascular risk associated with rofecoxib before its withdrawal as an example to inform future postmarket pharmaceutical safety surveillance efforts.

METHODS

We conducted a cumulative subject-level pooled analysis of data from all randomized, placebo-controlled trials of rofecoxib conducted by the manufacturer before September 2004. Our main outcome measurement was incidence of any investigator-reported death from any cause or cardiovascular thromboembolic (CVT) adverse event.

RESULTS

We identified 30 randomized, placebo-controlled trials of rofecoxib that enrolled a combined 20 152 subjects. Trial duration ranged from 4 weeks to 4 years; enrollment ranged from 17 to 2586 subjects prescribed either rofecoxib or placebo; and rofecoxib dose ranged from 12.5 mg to 50 mg. As of December 2000, 21 of these trials had been completed (70%), and the risk of a CVT adverse event or death was greater among subjects assigned to the rofecoxib group (rate ratio [RR], 2.18; 95% confidence interval [CI], 0.93-5.81) (P = .07), raising concerns from a safety standpoint. Subsequently collected data through June 2001 showed that rofecoxib was associated with a 35% increased risk of a CVT adverse event or death (RR, 1.35; 95% CI, 1.00-1.96) (P = .05). Analyzing data available as of April 2002, we found a 39% increased risk (RR, 1.39; 95% CI, 1.07-1.80) (P = .02), and using data available as of September 2004, we found a 43% increased risk (RR,1.43; 95% CI, 1.16-1.76) (P < .001).

CONCLUSION

Cumulative pooled analysis of all randomized, placebo-controlled trials demonstrates a trend toward increased cardiovascular risk associated with rofecoxib compared with placebo as early as December 2000, the comparison reaching a P value of .05 by June 2001, nearly 3(1/2) years before the manufacturer's voluntary market withdrawal.

Can peripheral leukocytes be used as Alzheimer's disease biomarkers?

Alzheimer's disease (AD) is the leading cause of dementia in elderly populations throughout the world and its incidence is on the rise. Current clinical diagnosis of AD requires intensive examination that includes neuropsychological testing and costly brain imaging techniques, and a definitive diagnosis can only be made upon postmortem neuropathological examination. Additionally, antemortem clinical AD diagnosis is typically administered following onset of cognitive and behavioral symptoms. As these symptoms emerge relatively late in disease progression, therapeutic intervention occurs after significant neurodegeneration, thereby limiting efficacy. The identification of noninvasive diagnostic biomarkers of AD is becoming increasingly important to make diagnosis more widely available to clinics with limited access to neuropsychological testing or state-of-the-art brain imaging, reduce the cost of clinical diagnosis, provide a biological measure to track the course of therapeutic intervention, and most importantly, allow for earlier diagnosis--possibly even during the prodromal phase--with hopes of therapeutic intervention prior to appreciable neurodegeneration. Circulating leukocytes are attractive candidate AD biomarkers as they can be obtained in a minimally invasive manner and are easily analyzed by widely available flow cytometry techniques. In this review, we critically analyze the potential utility of peripheral leukocytes as biological markers for AD.

An update on treatment and prevention strategies for Alzheimer's disease

With the aging of the population, the incidence and prevalence of Alzheimer's disease will grow, increasing the burden on individuals and society. While ameliorating symptoms, the currently available treatments approved by the US Food and Drug Administration do not halt progression or cure the illness. This article discusses recent data on treatment strategies targeting amyloid and tau pathology. Novel therapeutic strategies such as inhibitors of receptors for advanced glycation end products (RAGE), potential mitochondrial modification with Dimebon, anti-inflammatory approaches, and cholesterol-lowering agents are also reviewed. An update on results from pharmacologic and nonpharmacologic prevention trials is provided.

Neuroinflammation and memory: the role of prostaglandins

Neuroinflammation is a complex response to brain injury involving the activation of glia, release of inflammatory mediators within the brain, and recruitment of peripheral immune cells. Interestingly, memory deficits have been observed following many inflammatory states including infection, traumatic brain injury (TBI), normal aging, and Alzheimer's disease (AD). Prostaglandins (PGs), a class of lipid mediators which can have inflammatory actions, are upregulated by these inflammatory challenges and can impair memory. In this paper, we critically review the success of nonsteroidal anti-inflammatory drugs, which prevent the formation of PGs, in preventing neuroinflammation-induced memory deficits following lipopolysaccharide injection, TBI, aging, and experimental models of AD in rodents and propose a mechanism by which PGs could disrupt memory formation.

Disease progression meta-analysis model in Alzheimer's disease

BACKGROUND

Various authors have evaluated disease progression in Alzheimer's disease (AD), using patient data from individual clinical studies or pooled data across various trials. We conducted a systematic review of public data sources from 1990 to 2008 for all available AChE inhibitor studies, as well as clinical studies that evaluated the rate of deterioration in AD patients. Unique to this analysis, we developed a model based on literature data to describe the longitudinal response in the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog) (change from baseline) in mild to moderate severity AD patients. The model was used to estimate disease progression for both placebo-treated patients and acetylcholinesterase (AChE)-inhibitor treated patients, and factors that affected disease progression.

METHODS

We collected 576 mean ADAS-cog changes from baseline data points of 52 trials, representing data from approximately 19,972 patients and more than 84,000 individual observations. The model described the rate of disease progression, the evident placebo effect, and the symptomatic effect of AChE-inhibitors. Baseline ADAS-cog, Mini-Mental State Examination score, age, and year of publication were tested as covariates.

RESULTS

The disease progression in mild to moderate AD patients across all available and relevant literature sources was estimated as 5.5 points per year. An Emax-type model best described the symptomatic drug effect of AChE inhibitors. The rate of disease progression (underlying disease progression) was no different between placebo and AChE-inhibitors groups. Baseline ADAS-cog is a significant covariate in disease progression. Baseline age was also tested as a covariate in the rate of disease progression, but the model was unable to describe any effects of age, likely because of the narrow distribution of mean age (literature-level analysis). There was no significant impact of publication year in the model.

CONCLUSIONS

Baseline ADAS-cog is a significant covariate affecting the rate of disease progression, and it describes or at least explains the different rates of deterioration evident in early or late stages of the disease. There was no significant impact of publication year in the model, suggesting that disease progression has not slowed in more recent trials.

A randomized controlled study on effects of ibuprofen on cognitive progression of Alzheimer's disease

BACKGROUND AND AIMS

Epidemiological studies have examined the association between the use of non-steroidal anti-inflammatory drugs (NSAIDs) and the risk of Alzheimer's disease (AD). Recently, a variety of experimental studies indicates that a subset of NSAIDs, such as ibuprofen or flurbiprofen, also have Abeta-lowering properties in both AD transgenic mice and cell cultures of peripheral, glial and neuronal origin. In this trial, we evaluated whether the non-selective NSAID ibuprofen slows disease progression in patients with mild to moderate AD.

METHODS

This was a 12-month multicenter, randomized, double-blind, placebo-controlled, parallel group trial. Participants with mild-moderate AD (Mini-Mental State Examination score >15, <26; Clinical Dementia Rating= 0.5-1), 65 years or older, with reliable caregivers, were recruited between April 2003 and September 2004. Seven AD Outpatient Treatment Centers screened 530 patients, 132 of whom were enrolled. Intervention consisted of 400 mg ibuprofen twice a day or placebo, together with 20 mg once a day of esomeprazol, or placebo. The primary measure was any one-year change in the Alzheimer Disease Assessment Scale- Cognitive (ADAS-Cog) subscale score. Secondary measures included changes in MMSE, CDR, Basic and Instrumental Activities of Daily Living scales, and Neuropsychiatric Inventory (NPI).

RESULTS

Fifty-one patients (77%) in the ibuprofen vs 46 (70%) in the placebo group completed the protocol (p>0.20). In intention-to- treat analysis, ADAS-Cog score worsening was similar in the two groups (p=0.951, treatment difference= 0.1, CI -2.7; 2.9). No differences were found for any secondary outcomes. In a subsample of genotyped patients, ApoE epsilon4 carriers treated with ibuprofen (n=27) were the only group without significant cognitive decline.

CONCLUSIONS

Ibuprofen, if used for relatively short periods of time and although well tolerated thanks to gastroprotection, does not seem to be effective in tertiary prevention of mild-moderate AD. Our results suggest the need to examine whether differences in the response to NSAIDs exist, based on ApoE epsilon4 carrier status.

The distinct roles of cyclooxygenase-1 and -2 in neuroinflammation: implications for translational research

Cyclooxygenases (COX-1 and COX-2) are key enzymes in the conversion of arachidonic acid to prostaglandins and other lipid mediators. Because it can be induced by inflammatory stimuli, COX-2 has been classically considered as the most appropriate target for anti-inflammatory drugs. However, recent data indicate that COX-2 can mediate neuroprotection and that COX-1 is a major player in the neuroinflammatory process. We discuss the specific contributions of COX-1 and COX-2 in various neurodegenerative diseases and in models of neuroinflammation. We suggest that, owing to its predominant localization in microglia, COX-1 might be the major player in neuroinflammation, whereas COX-2, which is localized in neurons, might have a major role in models in which the neurons are directly challenged. Overall, the benefit of using COX-2 inhibitors should be carefully evaluated and COX-1 preferential inhibitors should be further investigated as a potential therapeutic approach in neurodegenerative diseases with an inflammatory component.

Ibuprofen treatment modifies cortical sources of EEG rhythms in mild Alzheimer's disease

OBJECTIVE

Non-steroidal anti-inflammatory drugs such as ibuprofen have a protective role on risk of Alzheimer's disease (AD). Here we evaluated the hypothesis that long-term ibuprofen treatment affects cortical sources of resting electroencephalographic (EEG) rhythms in mild AD patients.

METHODS

Twenty-three AD patients (13 treated AD IBUPROFEN; 10 untreated AD PLACEBO) were enrolled. Resting EEG data were recorded before and 1 year after the ibuprofen/placebo treatment. EEG rhythms were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). LORETA was used for EEG source analysis.

RESULTS

In the AD PLACEBO group, amplitude of delta sources was globally greater at follow-up than baseline. Instead, amplitude of delta sources remained stable or decreased in the majority of the AD IBUPROFEN patients. Clinical (CDR) but not global cognitive status (MMSE) reflected EEG results.

CONCLUSIONS

These results suggest that in mild AD patients, a long-term ibuprofen treatment slightly slows down the progressive increment of delta rhythms as a sign of contrast against the neurodegenerative processes.

SIGNIFICANCE

They motivate future investigations with larger population and extended neuropsychological testing, to study the relationships among ibuprofen treatment, delta cortical sources, and higher order functions.

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.

Preventing Alzheimer's disease : separating fact from fiction

Alzheimer's disease is an ever-increasing health concern among the aging population, and as we research new and existing treatments for this disease we begin to uncover possibilities for its prevention. Observational studies and animal models have provided promising findings and generated excitement, but placebo-controlled clinical trials are required to demonstrate true efficacy for these treatments.In the past two decades, clinical trials have led to the approval of symptomatic treatments for Alzheimer's disease, including cholinesterase inhibitors and, more recently, an NMDA receptor antagonist. Clinical trials have also examined antioxidants, NSAIDs, hormone replacement, nutritional supplements and nonpharmacological interventions for the treatment and prevention of Alzheimer's disease. While the results of many of these trials have been disappointing, new mechanisms targeting the hallmark pathology of Alzheimer's disease are currently under investigation, including immunotherapy and secretase modulation, targeted at reducing the amyloid burden, for which we await the results. We review the evidence from completed trials, support for ongoing studies and propose directions for future research.

Inflammatory response in the hippocampus of PS1M146L/APP751SL mouse model of Alzheimer's disease: age-dependent switch in the microglial phenotype from alternative to classic

Although the microglial activation is concomitant to the Alzheimer's disease, its precise role (neuroprotection vs neurodegeneration) has not yet been resolved. Here, we show the existence of an age-dependent phenotypic change of microglial activation in the hippocampus of PS1xAPP model, from an alternative activation state with Abeta phagocytic capabilities (at 6 months) to a classic cytotoxic phenotype (expressing TNF-alpha and related factors) at 18 months of age. This switch was coincident with high levels of soluble Abeta oligomers and a significant pyramidal neurodegeneration. In vitro assays, using astromicroglial cultures, demonstrated that oligomeric Abeta42 and soluble extracts from 18-month-old PS1xAPP hippocampus produced a potent TNF-alpha induction whereas monomeric Abeta42 and soluble extract from 6- or 18-month-old control and 6-month-old PS1xAPP hippocampi produced no stimulation. This stimulatory effect was avoided by immunodepletion using 6E10 or A11. In conclusion, our results show evidence of a switch in the activated microglia phenotype from alternative, at the beginning of Abeta pathology, to a classical at advanced stage of the disease in this model. This change was induced, at least in part, by the age-dependent accumulation of extracellular soluble Abeta oligomers. Finally, these cytotoxic activated microglial cells could participate in the neuronal lost observed in AD.

Drug therapy in Alzheimer disease: an update for the oral health care provider

Alzheimer disease (AD) is a progressive neurologic disorder that manifests as memory loss, personality changes, global cognitive dysfunction, and functional impairment. As the United States population continues to age, the prevalence of AD will rise. Accordingly, oral health care providers will be more likely to treat patients affected by this disease; therefore, it is necessary to understand the pharmacologic agents used for the management of AD. This article provides an update of the available drug therapies for AD and discusses their implications on the oral and dental health of patients.

Clinical trial design issues in mild to moderate Alzheimer disease

The field of clinical trials and therapeutics in Alzheimer disease (AD) is little more than 20 years old. Considerable progress has been made in crafting appropriate designs for clinical trials of promising therapeutic agents for AD. This article reviews basic issues in diagnostic criteria, choice of outcome measures, duration of trials and analytic strategies. Through trial and error, a general set of strategies has evolved for the assessment of putative therapies for mild to moderate AD. The experience of the past 2 decades has set the stage for discovering the next generation of anti-AD drugs and introducing those therapies at milder stages of the disease.

Non-amyloid approaches to neuroprotection

The introduction of the amyloid hypothesis, which identifies amyloid as the primary target for treating Alzheimer’s disease (AD), was a watershed in the field of AD research. Treatment approaches have since focused on how amyloid might be manipulated. In fact, there are challenges to amyloid manipulation. First, removal of amyloid has shown minimal clinical effects. Second, some data indicate that secretase modulation shows hints of stimulating feedback systems, which cause concern over how to effectively manipulate amyloid. Third, side-effect profiles of the direct manipulation of amyloid are not currently optimal. Finally, evidence suggests that cell and synapse loss may be better markers of dementia and its severity. Alternative approaches to direct manipulation of amyloid include antioxidant mechanisms for prevention, anti-inflammatory mechanisms for neuroprotection, manipulation of metabolic risks, modification of tau accumulation, and neuroregeneration.

These alternative mechanisms of action provide support for a wide range of potential agents for clinical trials. The exact connection between mechanism of action and clinical outcomes is not well defined, but typically trial designs using these mechanisms attempt to measure affects on disease progression, often with longer studies that include established clinical outcomes accompanied by putative biomarkers of disease. One trend that has provided much information has been to examine the effects of these drugs in subjects at risk for AD, thereby expanding the intervention to prevention of disease. These studies include both secondary prevention studies, for example deferring onset in those with prodromal disease such as mild cognitive impairment (MCI), and primary prevention directed at those with no specific signs or symptoms.

The role of antioxidant supplement in immune system, neoplastic, and neurodegenerative disorders: a point of view for an assessment of the risk/benefit profile

This review will discuss some issues related to the risk/benefit profile of the use of dietary antioxidants. Thus, recent progress regarding the potential benefit of dietary antioxidants in the treatment of chronic diseases with a special focus on immune system and neurodegenerative disorders will be discussed here. It is well established that reactive oxygen species (ROS) play an important role in the etiology of numerous diseases, such as atherosclerosis, diabetes and cancer. Among the physiological defense system of the cell, the relevance of antioxidant molecules, such as glutathione and vitamins is quite well established. Recently, the interest of researchers has, for example, been conveyed on antioxidant enzyme systems, such as the heme oxygenase/biliverdin reductase system, which appears modulated by dietary antioxidant molecules, including polyphenols and beta-carotene. These systems possibly counteract oxidative damage very efficiently and finally modulate the activity of oxidative phenomena occurring, for instance, during pathophysiological processes. Although evidence shows that antioxidant treatment results in cytoprotection, the potential clinical benefit deriving from both nutritional and supplemental antioxidants is still under wide debate. In this line, the inappropriate assumption of some lipophylic vitamins has been associated with increased incidence of cancer rather than with beneficial effects.

Blockade of chloride intracellular ion channel 1 stimulates Abeta phagocytosis

In amyloid-beta (Abeta)-stimulated microglial cells, blockade of chloride intracellular ion channel 1 (CLIC1) reverts the increase in tumor necrosis factor-alpha and nitric oxide (NO) production and results in neuroprotection of cocultured neurons. This effect could be of therapeutic efficacy in Alzheimer's disease (AD), where microglial activation may contribute to neurodegeneration, but it could reduce Abeta phagocytosis, which could facilitate amyloid plaque removal. Here, we analyzed the CLIC1 blockade effect on Abeta-stimulated mononuclear phagocytosis. In the microglial cell line BV-2, Abeta25-35 treatment enhanced fluorescent bead phagocytosis, which persisted also in the presence of IAA-94, a CLIC1 channel blocker. The same result was obtained in rat primary microglia and in BV2 cells, where CLIC1 expression had been knocked down with a plasmid producing small interfering RNAs. To address specifically the issue of Abeta phagocytosis, we treated BV-2 cells with biotinylated Abeta1-42 and measured intracellular amyloid by morphometric analysis. IAA-94-treated cells showed an increased Abeta phagocytosis after 24 hr and efficient degradation of ingested material after 72 hr. In addition, we tested Abeta1-42 phagocytosis in adult rat peritoneal macrophages. Also, these cells actively phagocytosed Abeta1-42 in the presence of IAA-94. However, the increased expression of inducible NO synthase (iNOS), stimulated by Abeta, was reverted by IAA-94. In parallel, a decrease in NO release was detected. These results suggest that blockade of CLIC1 stimulates Abeta phagocytosis in mononuclear phagocytes while inhibiting the induction of iNOS and further point to CLIC1 as a possible therapeutic target in AD.

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.

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.

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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

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Grants

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

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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

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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.

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.

Disease-modifying therapies in Alzheimer's disease

Alzheimer's disease (AD) is a chronic, progressive, neurodegenerative disorder that places a substantial burden on patients, their families, and society. The disease affects approximately 5 million individuals in the United States, with an annual cost of care greater than $100 billion. During the past dozen years, several agents have been approved that enhance cognition and global function of AD patients, and recent advances in understanding AD pathogenesis has led to the development of numerous compounds that might modify the disease process. A wide array of antiamyloid and neuroprotective therapeutic approaches are under investigation on the basis of the hypothesis that amyloid beta (A beta) protein plays a pivotal role in disease onset and progression and that secondary consequences of A beta generation and deposition, including tau hyperphosphorylation and neurofibrillary tangle formation, oxidation, inflammation, and excitotoxicity, contribute to the disease process. Interventions in these processes with agents that reduce amyloid production, limit aggregation, or increase removal might block the cascade of events comprising AD pathogenesis. Reducing tau hyperphosphorylation, limiting oxidation and excitotoxicity, and controlling inflammation might be beneficial disease-modifying strategies. Potentially neuroprotective and restorative treatments such as neurotrophins, neurotrophic factor enhancers, and stem cell-related approaches are also under investigation.

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

A doença de Alzheimer: aspectos fisiopatológicos e farmacológicos

A doença de Alzheimer é a patologia neurodegenerativa mais freqüente associada à idade, cujas manifestações cognitivas e neuropsiquiátricas resultam em deficiência progressiva e incapacitação. A doença afeta aproximadamente 10% dos indivíduos com idade superior a 65 anos e 40% acima de 80 anos. Estima-se que, em 2050, mais de 25% da população mundial será idosa, aumentando, assim, a prevalência da doença. O sintoma inicial da doença é caracterizado pela perda progressiva da memória recente. Com a evolução da patologia, outras alterações ocorrem na memória e na cognição, entre elas as deficiências de linguagem e nas funções vísuo-espaciais. Esses sintomas são freqüentemente acompanhados por distúrbios comportamentais, incluindo agressividade, depressão e alucinações. O objetivo deste trabalho foi revisar, na literatura médica, os principais aspectos que envolvem a doença de Alzheimer, como as características histopatológicas, a neuroinflamação e a farmacoterapia atual.

Elevated microsomal prostaglandin-E synthase-1 in Alzheimer's disease

BACKGROUND

The proinflammatory prostaglandin E(2) (PGE(2)) fluctuates over time in the cerebrospinal fluid of patients with Alzheimer's disease (AD), but the cerebral distribution and expression patterns of microsomal prostaglandin-E synthase (mPGES)-1 have not been compared with those of normal human brains.

METHODS

Middle frontal gyrus tissue from AD and age-matched control brains was analyzed by Western blot, immunofluorescence, and immunohistochemistry with mPGES-1-specific antibodies.

RESULTS

Western blotting revealed that mPGES-1 expression was significantly elevated in AD tissue. Furthermore, immunofluorescence of mPGES-1 was observed in neurons, microglia, and endothelial cells of control and AD tissue. Although mPGES-1 was consistently present in astrocytes of control tissue, it was present in only some astrocytes of AD tissue. Immunohistochemical staining suggested that mPGES-1 was elevated in pyramidal neurons of AD tissue when compared with controls.

CONCLUSIONS

The results suggest that mPGES-1 is normally expressed constitutively in human neurons, microglia, astrocytes, and endothelial cells but is up-regulated in AD.

AD2000 Collaborative Group, Bentham P, Gray R, Sellwood E, Hills R, Crome P, Raftery J. Aspirin in Alzheimer's disease (AD2000): a randomised open-label trial

BACKGROUND

Cardiovascular risk factors and a history of vascular disease can increase the risk of Alzheimer's disease (AD). AD is less common in aspirin users than non-users, and there are plausible biological mechanisms whereby aspirin might slow the progression of either vascular or Alzheimer-type pathology. We assessed the benefits of aspirin in patients with AD.

METHODS

310 community-resident patients who had AD and who had no potential indication or definite contraindication for aspirin were randomly assigned to receive open-label aspirin (n=156; one 75-mg enteric-coated tablet per day, to continue indefinitely) or to avoid aspirin (n=154). Primary outcome measures were cognition (assessed with the mini-mental state examination [MMSE]) and functional ability (assessed with the Bristol activities of daily living scale [BADLS]). Secondary outcomes were time to formal domiciliary or institutional care, progress of disability, behavioural symptoms, caregiver wellbeing, and care time. Patients were assessed at 12-week intervals in the first year and once each year thereafter. Analysis of the primary outcome measures was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN96337233.

FINDINGS

Patients had a median age of 75 years; 156 patients had mild AD, 154 had moderate AD, and 18 had concomitant vascular dementia. Over the 3 years after randomisation, in patients who took aspirin, mean MMSE score was 0.10 points higher (95% CI -0.37 to 0.57; p=0.7) and mean BADLS score was 0.62 points lower (-1.37 to 0.13; p=0.11) than in patients assigned to aspirin avoidance. There were no obvious differences between the groups in any other outcome measurements. 13 (8%) patients on aspirin and two (1%) patients in the control group had bleeds that led to admission to hospital (relative risk=4.4, 95% CI 1.5-12.8; p=0.007); three (2%) patients in the aspirin group had fatal cerebral bleeds.

INTERPRETATION

Although aspirin is commonly used in dementia, in patients with typical AD 2 years of treatment with low-dose aspirin has no worthwhile benefit and increases the risk of serious bleeds.

Vascular risk factors, cognitive decline, and dementia

Dementia is one of the most important neurological disorders in the elderly. Aging is associated with a large increase in the prevalence and incidence of degenerative (Alzheimer's disease) and vascular dementia, leading to a devastating loss of autonomy. In view of the increasing longevity of populations worldwide, prevention of dementia has turned into a major public health challenge. In the past decade, several vascular risk factors have been found to be associated with vascular dementia but also Alzheimer's disease. Some longitudinal studies, have found significant associations between hypertension, diabetus mellitus, and metabolic syndrome, assessed at middle age, and dementia. Studies assessing the link between hypercholesterolemia, atrial fibrillation, smoking, and dementia have given more conflicting results. Furthermore, some studies have highlighted the possible protective effect of antihypertensive therapy on cognition and some trials are evaluating the effects of statins and treatments for insulin resistance. Vascular risk factors and their treatments are a promising avenue of research for prevention of dementia, and further long-term, placebo-controlled, randomized studies, need to be performed.

Inflammation, genes and zinc in Alzheimer's disease

Alzheimer's disease (AD) is a heterogeneous and progressive neurodegenerative disease which in Western society mainly accounts for clinical dementia. AD has been linked to inflammation and metal biological pathway. Neuro-pathological hallmarks are senile plaques, resulting from the accumulation of several proteins and an inflammatory reaction around deposits of amyloid, a fibrillar protein, Abeta, product of cleavage of a much larger protein, the beta-amyloid precursor protein (APP) and neurofibrillary tangles. Amyloid deposition, due to the accumulation of Abeta peptide, is the main pathogenetic mechanism. Inflammation clearly occurs in pathologically vulnerable regions of AD and several inflammatory factors influencing AD development, i.e. environmental factors (pro-inflammatory phenotype) and/or genetic factors (pro-inflammatory genotype) have been described. At the biochemical level metals such as zinc are known to accelerate the aggregation of the amyloid peptide and play a role in the control of inflammatory responses. In particular, zinc availability may regulate mRNA cytokine expression, so influencing inflammatory network phenotypic expression.

Inflammatory changes parallel the early stages of Alzheimer disease

Alzheimer disease (AD) is the most prominent cause of dementia in the elderly. To determine changes in the AD brain that may mediate the transition into dementia, the gene expression of approximately 10,000 full-length genes was compared in mild/moderate dementia cases to non-demented controls that exhibited high AD pathology. Including this latter group distinguishes this work from previous studies in that it allows analysis of early cognitive loss. Compared to non-demented high-pathology controls, the hippocampus of AD cases with mild/moderate dementia had increased gene expression of the inflammatory molecule major histocompatibility complex (MHC) II, as assessed with microarray analysis. MHC II protein levels were also increased and inversely correlated with cognitive ability. Interestingly, the mild/moderate AD dementia cases also exhibited decreased number of T cells in the hippocampus and the cortex compared to controls. In conclusion, transition into AD dementia correlates with increased MHC II(+) microglia-mediated immunity and is paradoxically paralleled by a decrease in T cell number, suggesting immune dysfunction.

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.

Alzheimer’s disease and genetics of inflammation: a pharmacogenomic vision

Inflammation plays a key role in Alzheimer disease, and dissecting the genetics of inflammation may provide an answer to the possible treatment. The next-generation therapy is based on a pharmacogenomics that will reconure new approaches to a drug used on definite people with specific dosage. The translation of pharmacogenomics into clinical practice will allow bold steps to be taken toward personalized medicine. In response to tissue injury elicited by trauma or infection, the inflammatory response sets in as a complex network of molecular and cellular interactions, directed to facilitate a return to physiological homeostasis and tissue repair. The role of an individual’s genetic background and predisposition for the extent of an inflammatory response is determined by variability of genes encoding endogenous mediators that constitute the pathways of inflammation. Due to its clinical relevance, in this review, the view on genetics of inflammation will be illustrated through a description of the genetic basis of a specific inflammatory disease, Alzheimer’s disease (AD). Several studies report a significantly different distribution, in patients and controls, of proinflammatory genes, alleles of which are under-represented in control subjects and over-represented in patients affected by AD. These studies will permit the detection of a risk profile that will potentially allow both the early identification of individuals susceptible to disease and the possible design or utilization of drug at the right dose for a desired effect – a pharmacogenomic approach for this disease.

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.

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.

Looking for novel ways to treat the hallmarks of Alzheimer's disease

Alzheimer's disease (AD) represents an increasing public health issue as demographic changes and generally improved medical care result in a larger aged population. Although significant advances have been made in the diagnosis and treatment of AD, the unmet medical need remains and few treatment options are available. This review focuses on emerging therapies that aim to treat the underlying causes of the disease rather than the symptoms. Such disease-modifying treatments, focused on the two main hallmarks of the disease (plaques and tangles), include new and old targets which have significant potential in the field and are on the cusp of providing new treatment paradigms within the coming years.

Effective pharmacologic management of Alzheimer's disease

In order to assist physicians in the effective pharmacologic management of this challenging population, evidence-based pharmacologic treatment algorithms for the different stages of Alzheimer's disease have been developed. Evidence-based guidelines outlining pharmacotherapeutic strategies can be systematically implemented to optimize outcomes for patients in different stages of Alzheimer's disease. The first step toward the best possible long-term management is early diagnosis of Alzheimer's disease, thereby facilitating early initiation of cholinesterase inhibitor treatment, which may stabilize/reduce the rate of symptomatic cognitive and functional decline. Cholinesterase inhibitor therapy with rivastigmine, donepezil, or galantamine is endorsed as standard first-line therapy in patients with mild-to-moderate Alzheimer's disease. The N-methyl-D-aspartate receptor-antagonist, memantine, may be used as monotherapy or in combination with a cholinesterase inhibitor for patients with moderate Alzheimer's disease, and as monotherapy for patients with severe Alzheimer's disease. During treatment, cognitive and functional status should be monitored over 6-month intervals, and pharmacologic therapy should ideally be continued until there are no meaningful social interactions and quality of life has irreversibly deteriorated.