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

Scaffold of the cyclooxygenase-2 (COX-2) inhibitor carprofen provides Alzheimer gamma-secretase modulators

N-sulfonylated and N-alkylated carprofen derivatives were investigated for their inhibition and modulation of gamma-secretase, which is associated with Alzheimer's disease. The introduction of a lipophilic substituent transformed the COX-2 inhibitor carprofen into a potent gamma-secretase modulator. Several compounds (e.g., 9p, 11f) caused selective reduction of Abeta42 and an increase of Abeta38. The most active compounds displayed activities in the low micromolar range and no effect on the gamma-secretase cleavage at the e-site.

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).

Role of COX-2 in inflammatory and degenerative brain diseases

In the last decade, the potential role of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) in brain diseases has been extensively studied. COX-2 over-expression has been associated with neurotoxiticy in acute conditions, such as hypoxia/ischemia and seizures, as well as in inflammatory chronic diseases, including Creutzfeldt-Jakob disease (CJD) and Alzheimer's disease (AD). However, the role played by COX-2 in neurodegenerative diseases is still controversial and further clinical and experimental studies are warranted. In addition, the emerging role of COX-2 in behavioural and cognitive functions strongly indicates that studies aimed at improving our knowledge of the physiological role of COX-2 in the central nervous system are crucial to fully understand the pros and cons of its manipulation in disabling neurological diseases.

Recommendations for the diagnosis and management of Alzheimer's disease and other disorders associated with dementia: EFNS guideline

The aim of this international guideline on dementia was to present a peer-reviewed evidence-based statement for the guidance of practice for clinical neurologists, geriatricians, psychiatrists, and other specialist physicians responsible for the care of patients with dementia. It covers major aspects of diagnostic evaluation and treatment, with particular emphasis on the type of patient often referred to the specialist physician. The main focus is Alzheimer's disease, but many of the recommendations apply to dementia disorders in general. The task force working group considered and classified evidence from original research reports, meta-analysis, and systematic reviews, published before January 2006. The evidence was classified and consensus recommendations graded according to the EFNS guidance. Where there was a lack of evidence, but clear consensus, good practice points were provided. The recommendations for clinical diagnosis, blood tests, neuroimaging, electroencephalography (EEG), cerebrospinal fluid (CSF) analysis, genetic testing, tissue biopsy, disclosure of diagnosis, treatment of Alzheimer's disease, and counselling and support for caregivers were all revised when compared with the previous EFNS guideline. New recommendations were added for the treatment of vascular dementia, Parkinson's disease dementia, and dementia with Lewy bodies, for monitoring treatment, for treatment of behavioural and psychological symptoms in dementia, and for legal issues. The specialist physician plays an important role together with primary care physicians in the multidisciplinary dementia teams, which have been established throughout Europe. This guideline may contribute to the definition of the role of the specialist physician in providing dementia health care.

The Primary Care of Alzheimer Disease

Alzheimer disease is the most common cause of progressive irreversible intellectual loss in aging humans. The number of individuals and families affected by this disorder will continue to grow as society ages worldwide. Our understanding of the biology, underlying pathophysiology, and diagnosis of Alzheimer disease has greatly expanded over the past few years and much has been published in these areas. This review focuses on the primary care of this disorder and addresses the "now what" question. Topics examined include limiting excess disability, responding to commonly raised questions of family members, pharmacologic and nonpharmacologic therapeutic options, long-term planning, and caregiver issues.

Contributions of cyclooxygenase-2 to neuroplasticity and neuropathology of the central nervous system

Cyclooxygenase (COX) enzymes, or prostaglandin-endoperoxide synthases (PTGS), are heme-containing bis-oxygenases that catalyze the first committed reaction in metabolism of arachidonic acid (AA) to the potent lipid mediators, prostanoids and thromboxanes. Two isozymes of COX enzymes (COX-1 and COX-2) have been identified to date. This review will focus specifically on the neurobiological and neuropathological consequences of AA metabolism via the COX-2 pathway and discuss the potential therapeutic benefit of COX-2 inhibition in the setting of neurological disease. However, given the controversy surrounding the use of COX-2 selective inhibitors with respect to cardiovascular health, it will be important to move beyond COX to identify which down-stream effectors are responsible for the deleterious and/or potentially protective effects of COX-2 activation in the setting of neurological disease. Important advances toward this goal are highlighted herein. Identification of unique effectors in AA metabolism could direct the development of new therapeutics holding significant promise for the prevention and treatment of neurological disorders.

Clinical practice with anti-dementia drugs: a consensus statement from British Association for Psychopharmacology

The British Association for Psychopharmacology (BAP) coordinated a meeting of experts to review the evidence on the drug treatment for dementia. The level of evidence (types) was rated using a standard system: Types 1a and 1b (evidence from meta-analysis of randomised controlled trials or at least one controlled trial respectively); types 2a and 2b (one well-designed study or one other type of quasi experimental study respectively); type 3 (non-experimental descriptive studies); and type 4 (expert opinion). There is type 1a evidence for cholinesterase inhibitors (donepezil, rivastigmine and galantamine) for mild to moderate Alzheimer's disease; memantine for moderate to severe Alzheimer's disease; and for the use of bright light therapy and aromatherapy. There is type 1a evidence of no effect of anti inflammatory drugs or statins. There is conflicting evidence regarding oestrogens, with type 2a evidence of a protective effect of oestrogens but 1b evidence of a harmful effect. Type 1a evidence for any effect of B12 and folate will be forthcoming when current trials report. There is type 1b evidence for gingko biloba in producing a modest benefit of cognitive function; cholinesterase inhibitors for the treatment of people with Lewy body disease (particularly neuropsychiatric symptoms); cholinesterase inhibitors and memantine in treatment cognitive impairment associated with vascular dementia; and the effect of metal collating agents (although these should not be prescribed until more data on safety and efficacy are available). There is type 1b evidence to show that neither cholinesterase inhibitors nor vitamin E reduce the risk of developing Alzheimer's disease in people with mild cognitive impairment; and there is no evidence that there is any intervention that can prevent the onset of dementia. There is type 1b evidence for the beneficial effects of adding memantine to cholinesterase inhibitors, and type 2b evidence of positive switching outcomes from one cholinesterase inhibitor to another. There is type 2a evidence for a positive effect of reminiscence therapy, and type 2a evidence that cognitive training does not work. There is type 3 evidence to support the use of psychological interventions in dementia. There is type 2 evidence that a clinical diagnosis of dementia can be made accurately and that brain imaging increases that accuracy. Although the consensus statement dealt largely with medication, the role of dementia care in secondary services (geriatric medicine and old age psychiatry) and primary care, along with health economics, was discussed. There is ample evidence that there are effective treatments for people with dementia, and Alzheimer's disease in particular. Patients, their carers, and clinicians deserve to be optimistic in a field which often attracts therapeutic nihilism.

Therapy Insight: type 2 diabetes mellitus and the risk of late-onset Alzheimer's disease

A number of well-designed epidemiological studies have linked type 2 diabetes mellitus (T2DM) with an increased risk of Alzheimer's disease (AD). Several mechanisms could help to explain this proposed link, including insulin and insulin resistance, inflammatory cytokines, and oxidative stress. Obesity or physical inactivity might also influence AD through effects on hypertension, insulin sensitivity or inflammation. Typical AD pathology, such as amyloid-beta deposits, might be exacerbated by insulin dysregulation, T2DM itself, or microvascular disease that is a consequence of T2DM. T2DM patients are not routinely evaluated for cognitive outcomes, and cognitive impairment in T2DM is rarely treated. Similarly, AD patients are not routinely evaluated for T2DM or hyperinsulinemia. Current treatments for AD have only modest benefits, and several drugs that target metabolic and inflammatory pathways are being evaluated, most notably the statins, which reduce LDL and inflammation but might not influence amyloid- deposition, an important precursor for AD. Although some evidence supports a potentially important role for peroxisome proliferative activated receptor agonists such as glitazones, at present there are no published randomized clinical trials in AD patients of any drugs that target insulin or insulin resistance. Clinical implications of the T2DM-AD link include cognitive evaluations of patients with T2DM, and potential benefits for such patients through treatment with statins or diabetes drugs that target insulin.

Genetic risk profiles for Alzheimer's disease: integration of APOE genotype and variants that up-regulate inflammation

BACKGROUND

A number of studies associate Alzheimer's disease with APOE polymorphism and alleles which favor the increased expression of immunological mediators such as cytokines or acute phase proteins. We integrated this information to better define risk and determine the relative importance of APOE and immunological mediators.

METHODS

We investigated functional gene variants for APOE, IL-10 (3 loci), ACT (2 loci), HMGCR, IL-1alpha, IL-1beta, TNF-alpha, IFN-gamma, and IL-6 found for 260 AD patients and 190 controls enrolled in Northern Italy. A fuzzy latent classification approach, namely grade-of-membership analysis (GoM), was taken to identify extreme pure type risk sets, or profiles. This approach automatically relates individuals to each profile via graded membership scores.

FINDINGS

Four extreme pure type risk sets were identified. Set I defined low intrinsic risk and had a low probability of carrying pro-inflammatory alleles or APOE epsilon4. Three sufficient risk sets were identified: early onset AD (set II) was characterized by a high density of pro-inflammatory alleles, a rapid cognitive decline and independent of APOE epsilon4. Late onset AD had a lower density (ages 65-74, set III), or a subset homozygous (ages 75+, set IV), for these alleles and a high probability of one or two APOE epsilon4 alleles. A total of 97% of the subjects who were cases strongly resembled, i.e. had at least 50% membership in, the sufficient risk sets, as did 25% of middle aged control subjects. IL-10, HMGCR, ACT, and IL-1beta gene variants were each more informative in identifying the risk sets than was APOE.

INTERPRETATION

AD likely has many determinants including APOE polymorphism and gene variants that modulate innate immunity. Identification of these factors, risk prediction for individuals, and successful prevention and treatment trials require integration of relevant information.

Application of Clinical Trial Simulation to Compare Proof-of-Concept Study Designs for Drugs with a Slow Onset of Effect; An Example in Alzheimer's Disease

OBJECTIVE

Clinical trial simulation (CTS) was used to select a robust design to test the hypothesis that a new treatment was effective for Alzheimer's disease (AD). Typically, a parallel group, placebo controlled, 12-week trial in 200-400 AD patients would be used to establish drug effect relative to placebo (i.e., Ho: Drug Effect = 0). We evaluated if a crossover design would allow smaller and shorter duration trials.

MATERIALS AND METHODS

A family of plausible drug and disease models describing the time course of the AD assessment scale (ADAS-Cog) was developed based on Phase I data and literature reports of other treatments for AD. The models included pharmacokinetic, pharmacodynamic, disease progression, and placebo components. Eight alternative trial designs were explored via simulation. One hundred replicates of each combination of drug and disease model and trial design were simulated. A 'positive trial' reflecting drug activity was declared considering both a dose trend test (p < 0.05) and pair-wise comparisons to placebo (p < 0.025).

RESULTS

A 4 x 4 Latin Square design was predicted to have at least 80% power to detect activity across a range of drug and disease models. The trial design was subsequently implemented and the trial was completed. Based on the results of the actual trial, a conclusive decision about further development was taken. The crossover design provided enhanced power over a parallel group design due to the lower residual variability.

CONCLUSION

CTS aided the decision to use a more efficient proof of concept trial design, leading to savings of up to US 4 M dollars in direct costs and a firm decision 8-12 months earlier than a 12-week parallel group trial.

The role of biomarkers in clinical trials for Alzheimer disease

Biomarkers are likely to be important in the study of Alzheimer disease (AD) for a variety of reasons. A clinical diagnosis of Alzheimer disease is inaccurate even among experienced investigators in about 10% to 15% of cases, and biomarkers might improve the accuracy of diagnosis. Importantly for the development of putative disease-modifying drugs for Alzheimer disease, biomarkers might also serve as indirect measures of disease severity. When used in this way, sample sizes of clinical trials might be reduced, and a change in biomarker could be considered supporting evidence of disease modification. This review summarizes a meeting of the Alzheimer's Association's Research Roundtable, during which existing and emerging biomarkers for AD were evaluated. Imaging biomarkers including volumetric magnetic resonance imaging and positron emission tomography assessing either glucose utilization or ligands binding to amyloid plaque are discussed. Additionally, biochemical biomarkers in blood or cerebrospinal fluid are assessed. Currently appropriate uses of biomarkers in the study of Alzheimer disease, and areas where additional work is needed, are discussed.

Acetylcholinesterase inhibitors for Alzheimer's disease: anti-inflammatories in acetylcholine clothing!

The pathogenesis of Alzheimer's disease (AD) has been linked to a deficiency in the brain neurotransmitter acetylcholine. Subsequently, acetylcholinesterase inhibitors (AChEIs) were introduced for the symptomatic treatment of AD. The prevailing view has been that the efficacy of AChEIs is attained through their augmentation of acetylcholine-medicated neuron to neuron transmission. However, AChEIs also protect cells from free radical toxicity and beta-amyloid-induced injury, and increased production of antioxidants. In addition, it has been reported that AChEIs directly inhibit the release of cytokines from microglia and monocytes. These observations are supported by evidence showing a role for acetylcholine in suppression of cytokine release through a 'cholinergic anti-inflammatory pathway'. Based on the accumulating research data so far, it is no longer appropriate to consider that the sole action of AChEIs in AD is through direct acetylcholine-medicated enhancement of neuronal transmission. Evidence points to a possible anti-inflammatory role for these agents as well.

Is there a future for cyclo-oxygenase inhibitors in Alzheimer's disease?

Several epidemiological studies have indicated that the long-term use of NSAIDs, most of which are cyclo-oxygenase (COX) inhibitors, may reduce the risk of Alzheimer's disease. For this reason, anti-inflammatory COX-inhibiting NSAIDs have received increased attention in experimental and therapeutic trials for Alzheimer's disease. However, several recent efforts attempting to demonstrate a therapeutic effect of NSAIDs in Alzheimer's disease have largely failed. Clinicians and scientists currently believe that this lack of success may be attributable to two key problems: (i) clinical trials of NSAIDs have been conducted in patients with late-stage Alzheimer's disease, wherein advanced neurodegeneration may be refractory to anti-inflammatory drug treatment; and (ii) it is not known which of the large family of NSAIDs (i.e. COX-1, COX-2 or mixed inhibitors) is most efficacious in preventing Alzheimer's disease. The wide list of putative functions for COX in the brain, and the significant functional heterogeneity of NSAIDs, which appear to influence the beta-amyloid (Abeta) neuropathology associated with Alzheimer's disease via both COX-dependent and COX-independent pathways, complicate the interpretation of the mechanisms through which COX-inhibiting NSAIDs may beneficially influence Alzheimer's disease. As discussed in this review, for patients at high risk of developing Alzheimer's disease (e.g. those with mild cognitive impairment), preventative treatment with COX-inhibiting NSAIDs may ultimately represent a viable strategy in the management of clinical Alzheimer's disease. However, the recent evidence showing an increased risk of major cardiovascular events among patients treated with certain COX-1 and COX-2 inhibitors leaves many questions unanswered. We suggest that further investigation into the physiological role(s) of COXs in normal health and in disease conditions, and the identification of safer and better tolerated COX inhibitors, will provide renewed impetus to the application of anti-inflammatory strategies for the prevention and treatment of Alzheimer's disease.

Imaging and in vivo quantitation of beta-amyloid: an exemplary biomarker for Alzheimer's disease?

Alzheimer's disease (AD) is characterized pathologically by the presence of beta-amyloid plaques in the brain. A substantial body of research indicates that the presence of increased beta-amyloid peptide (Abeta) is neurotoxic and may initiate the further pathology observed in AD, including neurofibrillary tangles, synaptic loss and dysfunction, and neurodegeneration. The use of brain imaging in patients with or at risk for AD has increased our understanding of the pathophysiology of the disease and may potentially aid in diagnosis. The development of new therapeutics that reduce Abeta in the brain has also indicated a potential use for amyloid imaging in monitoring response to treatment. This review explores the utility of amyloid as a biomarker and the use of positron emission tomography and magnetic resonance imaging in the diagnosis and treatment of AD.

NSAIDs and Alzheimer disease: epidemiological, animal model and clinical studies

This review reports correlations between four independent fields related to inflammation and Alzheimer disease: fundamental pathology, epidemiology, transgenic animal studies and clinical trials. Activated microglia, along with a spectrum of inflammatory mediators, have been identified in association with the lesions of Alzheimer disease (AD), suggesting that antiinflammatory agents such as NSAIDs should protect against the disease. In multiple epidemiological investigations testing this hypothesis, a significant risk reduction, or a trend towards such a reduction has been observed in long term as opposed to short term users of traditional NSAIDs. In studies where such NSAIDs have been administered to AD transgenic mice, a dose dependent reduction in pathology was observed. The selective C0X-2 inhibitors were ineffective. Results of clinical investigations have so far been disappointing but have nevertheless correlated with fundamental pathological findings and with transgenic mouse results. Four clinical trials using selective COX-2 inhibitors failed which is in keeping with the animal results and is consistent with pathological findings demonstrating that COX-1 and not COX-2 is the appropriate target in activated human microglia. A low dose trial of the traditional NSAID naproxen also failed, but pilot trials using therapeutically established doses of indomethacin and diclofenac/misoprostol showed promise. Further clinical investigations with relatively high doses of traditional NSAIDs might be warranted, although significant side effects should be anticipated.

Emerging therapeutics for Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia, with prevalence and the accompanying socioeconomic impact set to increase over the coming decades. Currently available medications result, at best, in modest cognitive improvement. With increasing understanding of the underlying pathology, new therapeutic targets are being identified at an ever-increasing rate. The key pathological events in the AD brain are deposition of insoluble amyloid-beta peptide (Abeta), formation of neurofibrillary tangles and neuroinflammation leading, ultimately, to neuronal cell death. Each of these will be considered, in detail, in terms of the variety of therapeutic approaches currently being investigated and mechanisms that may prove amenable to intervention in the future.

Summary measures were a useful alternative for analyzing therapeutic clinical trial data

BACKGROUND AND OBJECTIVE

To compare use of both a pooled index and area under the curve (AUC) to the standard analysis of a randomized controlled trial of antibiotics for patients with Alzheimer's disease.

METHODS

Using data from a randomized, placebo-controlled trial of antibiotics for patients with Alzheimer's disease, a pooled index of six outcome measures was constructed. Each change score was standardized by dividing by the standard deviation, and the six standardized change scores were averaged. The Standardized Alzheimer's Disease Assessment Scale cognitive subscale and the pooled index were plotted against time and the AUC was calculated.

RESULTS

The AUC analysis of the pooled index showed significant treatment effect over the 12-month period. In contrast, none of the individual measures showed an effect at more than one time point. The AUC analyses of the Standardized Alzheimer's Disease Assessment Scale cognitive subscale, the primary outcome of the trial, showed no significant difference over the entire 12-month period, although the original individual time-point analysis showed a difference at 6 months alone.

CONCLUSION

Pooled indices and AUC analyses may provide important insight into therapeutic effect of agents tested in randomized clinical trials of patients with Alzheimer's disease.

Human amyloid β-induced neuroinflammation is an early event in neurodegeneration

Using a human amyloid beta (Abeta) intracerebroventricular infusion mouse model of Alzheimer's disease-related injury, we previously demonstrated that systemic administration of a glial activation inhibitor could suppress neuroinflammation, prevent synaptic damage, and attenuate hippocampal-dependent behavioral deficits. We report that Abeta-induced neuroinflammation is an early event associated with onset and progression of pathophysiology, can be suppressed by the glial inhibitor over a range of intervention start times, and is amenable to suppression without inhibiting peripheral tissue inflammatory responses. Specifically, hippocampal neuroinflammation and neurodegeneration occur in close time proximity at 4-6 weeks after the start of infusion. Intraperitoneal administration of inhibitor for 2-week intervals starting at various times after initiation of Abeta infusion suppresses progression of pathophysiology. The glial inhibitor is a selective suppressor of neuroinflammation, in that it does not block peripheral tissue production of proinflammatory cytokines or markers of B- and T-cell activation after a systemic lipopolysaccharide challenge. These results support a causal link between neuroinflammation and neurodegeneration, have important implications for future therapeutic development, and provide insight into the relative time window for targeting neuroinflammation with positive neurological outcomes.

Neuroprotection and neurodegenerative diseases: from biology to clinical practice

Neurodegenerative diseases and, in particular, Alzheimer disease, are characterized by progressive neuronal loss correlated in time with the symptoms of the disease considered. Whereas the symptoms of those incapacitating diseases are beginning to be managed with a relative efficacy, the ultimate objective of therapy nonetheless remains preventing cell (neuronal and/or astrocytic) death in a neurocytoprotective approach. In biologic terms, in the light of progress at basic research level, three strategies may be envisaged: (1) antagonizing the cytotoxic causal events (excess intracellular calcium, accumulation of abnormal proteins, excitotoxic effects of amino acids, oxidative stress, processes related to inflammation, etc.); (2) stimulating the endogenous protective processes (anti-free radical or DNA repair systems, production of neurotrophic factors, potential cytoprotective action of steroids, etc.); (3) promoting damaged structure repair strategies (grafts) or deep brain or cortical neurostimulation with a view to triggering (beyond the symptomatic actions) potential 'protective' cell mechanisms. The clinical transition of the various strategies whose efficacy is being tested in animal and/or cell models, experimental analogs of the diseases, and thus the objective demonstration in humans of pharmacological and/or surgical neurocytoprotection, is currently the subject of considerable methodological debate (What are the right psychometric assessment criteria? What are the most pertinent laboratory or neuroradiological markers, etc.?). A number of clinical trials have been completed or are ongoing with drugs that are reputed to be neuroprotective. Thus, elements of the response are beginning to be generated with a view to determining whether it will soon be possible to effectively slow or even stop the neurodegenerative process whose etiology, in most cases, remains obscure.

Novel therapeutic opportunities for Alzheimer's disease: focus on nonsteroidal anti-inflammatory drugs

Alzheimer's disease (AD) is the most common form of neurodegenerative disorder with dementia in the elderly. The AD brain pathology is characterized by deposits of amyloid-beta (Abeta) peptides and neurofibrillary tangles but also (among other aspects) by signs of a chronic inflammatory process. Epidemiological studies have shown that long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing AD and delays its onset. Classical targets of NSAIDs include cycloxygenase, nuclear factor kappaB, and peroxisome proliferator-activated receptors. Modulation of these pathways, all of which have been implicated in AD pathogenesis, could explain the NSAID effect on AD progression. However, recent studies indicate that a subset of NSAIDs such as ibuprofen, indomethacin, and flurbiprofen may have direct Abeta-lowering properties in cell cultures as well as transgenic models of AD-like amyloidosis. A renewed interest in the old and a discovery of new pharmacological properties of these drugs are providing vital insight for future clinical trials. In this review we will summarize how the combination of traditional (anti-inflammatory) and new (anti-amyloidogenic) properties of some NSAIDs is providing unprecedented opportunities for drug discovery and could potentially result in novel therapeutic approaches for the treatment of AD.

A time course analysis of cyclooxygenase-2 suggests a role in spatial memory retrieval in rats

We previously showed a role for COX-2 in spatial memory retention. In that study we investigated the effects of post-training intrahippocampal infusion of celecoxib as a COX-2-specific inhibitor on spatial memory retention. Those infusions impaired spatial memory retention in the Morris water maze. In the present study a time course analysis of role of COX-2 in spatial memory was conducted. Here stereotaxic surgery was employed for the bilateral implantation of guide cannulas into the CA1 region of the hippocampus. Training trials were started after recovery of the animals. Immediately after last trial of training on third day, the celecoxib (0.1M) was infused bilaterally and testing trials, were performed 1, 2, 3, and 7 days after celecoxib infusions. Significant alterations were observed in escape latency and traveled distance 2 and 3 days after celecoxib infusions. The maximum impairment was obtained 72 h after the infusions. The data suggests that the effect of celecoxib is transient and that its effect on performance is likely caused by a problem in memory retrieval. Quantification analyses of the immunostaining of COX-2-containing neurons in the dorsal hippocampus show that celecoxib infusions significantly reduced (P<0.05) COX-2 immunoreactivity for the animals that were tested 3 days after the drug infusion. Results from the behavioral study along with the findings from immunohistochemical analyses suggest that COX-2 has significant role in spatial memory retrieval. Moreover, the memory deficits induced by the infusions continuously persists for 3 days.

Glia as a therapeutic target: selective suppression of human amyloid-beta-induced upregulation of brain proinflammatory cytokine production attenuates neurodegeneration

A corollary of the neuroinflammation hypothesis is that selective suppression of neurotoxic products produced by excessive glial activation will result in neuroprotection. We report here that daily oral administration to mice of the brain-penetrant compound 4,6-diphenyl-3-(4-(pyrimidin-2-yl)piperazin-1-yl)pyridazine (MW01-5-188WH), a selective inhibitor of proinflammatory cytokine production by activated glia, suppressed the human amyloid-beta (Abeta) 1-42-induced upregulation of interleukin-1beta, tumor necrosis factor-alpha, and S100B in the hippocampus. Suppression of neuroinflammation was accompanied by restoration of hippocampal synaptic dysfunction markers synaptophysin and postsynaptic density-95 back toward control levels. Consistent with the neuropathophysiological improvements, MW01-5-188WH therapy attenuated deficits in Y maze behavior, a hippocampal-linked task. Oral MW01-5-188WH therapy begun 3 weeks after initiation of intracerebroventricular infusion of human Abeta decreased the numbers of activated astrocytes and microglia and the cytokine levels in the hippocampus without modifying amyloid plaque burden or altering peripheral tissue cytokine upregulation in response to an in vivo inflammatory challenge. The results provide a novel integrative chemical biology proof in support of the neuroinflammation hypothesis of disease progression, demonstrate that neurodegeneration can be attenuated independently of plaque modulation by targeting innate brain proinflammatory cytokine responses, and indicate the feasibility of developing efficacious, safe, and selective therapies for neurodegenerative disorders by targeting key glial activation pathways.

Coxibs and Alzheimer's disease: Should they stay or should they go?

The neuropathology of Alzheimer's disease (AD) is characterized by deposits of amyloid beta (Abeta) peptides and neurofibrillary tangles, but also, among other aspects, by signs of a chronic inflammatory process. Epidemiological studies have shown that long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) reduces the risk of developing AD and delays its onset. The classic target of NSAIDs is the prevention of cyclooxygenase (COX) activation. The main mechanism of action of COXs is the synthesis of prostaglandins, some of which have potent inflammatory activity. The discovery of two isoforms of this enzyme, COX-1 and COX-2, and that the latter is inducible by inflammatory cytokines supported the hypothesis that its inhibition would result in a potent antiinflammatory effect and led to the rapid development of selective COX-2 inhibitors, collectively called coxibs. Based on this rationale, some coxibs have been used in clinical trials for AD patients, but all the results obtained so far have been negative. Here, we review our knowledge in terms of COX-2 in the central nervous system, COX-2 and Abeta formation, and finally COX-2 and AD pathogenesis to understand the reasons why these drugs have failed and whether there is any scientific support to keep them as therapeutic tools for this chronic disease.

Heme oxygenase and cyclooxygenase in the central nervous system: A functional interplay

Heme oxygenase (HO) and cyclooxygenase (COX) are two hemeproteins involved in the regulation of several functions in the nervous system. Heme oxygenase is the enzyme responsible for the degradation of heme into ferrous iron, carbon monoxide (CO), and biliverdin, the latter being further reduced in bilirubin (BR) by biliverdin reductase. Heme oxygenase-derived CO is a gaseous neuromodulator and plays an important role in the synaptic plasticity, learning and memory processes, as well as in the regulation of hypothalamic neuropeptide release, whereas BR is an endogenous molecules with antioxidant and anti-nitrosative activities. Cyclooxygenase is considered a pro-inflammatory enzyme as free radicals and prostaglandins (PGs) are produced during its catalytic cycle. Although PGs are also involved in a variety of physiologic conditions including angiogenesis, hemostasis, or regulation of kidney function, upregulation of COX and increase in PGs levels are a common feature of neuroinflammation. In the brain, a functional interplay exists between HO and COX. Heme oxygenase regulates COX activity by reducing the intracellular heme content or by generating CO, which stimulates PGE(2) release. Increased levels of PGs, free radicals, and the associated oxidative stress serve in the brain as a trigger for the induction of HO isoforms which increases cellular antioxidant defenses to counteract oxidative damage. The importance of the interaction between HO and COX in the regulation of physiologic brain functions, and its relevance to neuroprotective or neurodegenerative mechanisms are discussed.

5-Lipoxygenase (ALOX5) and FLAP (ALOX5AP) gene polymorphisms as factors in vascular pathology and Alzheimer’s disease

We first hypothesized in 2000 that a polymorphism of the human gene encoding the enzyme 5-lipoxygenase (5-LOX) might be associated with Alzheimer's disease. Only a little progress has been made in directly testing our proposal. However, additional important new data lead us to hypothesize that genetic variability not only in the 5-LOX gene, i.e., ALOX5, but also in polymorphism of the five-lipoxygenase activating protein (FLAP) gene, i.e., ALOX5AP, may be associated with Alzheimer's pathology. Studies in mice followed by several extensive clinical studies have identified ALOX5 and ALOX5AP polymorphisms as strong risk factors for atherosclerosis and cerebrovascular pathologies. New data point to a significant aggregation of vascular risk factors and risk of Alzheimer's disease. Preliminary findings in postmortem brain of Alzheimer's patients identified elevated 5-LOX immunostaining in this disease. We suggest that our hypothesis of a link between the ALOX5 and ALOX5AP gene polymorphisms and Alzheimer's disease could be tested in a clinical setting and in animal models, i.e., transgenic mice could be produced by crossing the available 5-LOX-deficient mice with the available transgenic mice models of Alzheimer's disease.

Prevention of anti-inflammatory drug-induced gastrointestinal damage: benefits and risks of therapeutic strategies

Patients who take non-steroidal anti-inflammatory drugs (NSAIDs) may develop serious gastrointestinal (GI) side effects in both the upper and lower GI tract. Those at risk should be considered for prevention with misoprostol, proton pump inhibitor (PPI) or COX-2 selective inhibitor (coxib) therapy. A coxib or an NSAID+PPI combination is considered to have comparable GI safety profiles, but evidence from direct comparison is limited. PPIs are effective in the prevention of upper GI events in endoscopy trials and in a few, small, outcome trials in patients at risk. Coxibs have been evaluated in endoscopic ulcer studies and clinical outcome trials, and shown to significantly reduce the risk of upper GI ulcer and complications. Moreover, unlike PPIs, coxibs significantly reduce toxicity in the lower GI tract compared with NSAIDs. Coxibs and possibly some NSAIDs also increase the risk of developing serious cardiovascular events, an effect which may depend on the drug, dose and duration of therapy. It is not known whether concomitant low-dose aspirin use, which occurs in more than 20% of patients, will reduce the incidence of cardiovascular events, although concomitant aspirin increases the risk of developing serious GI events in patients taking either an NSAID or a coxib. Such patients may require additional PPI co-therapy. Current prevention strategies with an NSAID+PPI, misoprostol or a coxib must be considered in the individual patient with GI and cardiovascular risk factors. A PPI+coxib is indicated in those at highest risk (e.g. previous ulcer bleeding). PPI therapy must be considered for the treatment and prevention of NSAID-induced dyspepsia.

Clinical aspects of inflammation in Alzheimer's disease

In Alzheimer's disease (AD) there is increasing evidence that neurotoxicity is mediated by CNS inflammatory processes. These processes involve activation of microglia by amyloid-beta leading to release of pro-inflammatory cytokines including IL-1beta, IL-6, and TNF-alpha among others. Neurotoxic processes mediated by these cytokines may include direct neuronal death by enhancement of apoptosis, decreased synaptic function as evidence by inhibition of long-term potentiation, and inhibition of hippocampal neurogenesis. Central nervous system (CNS) inflammation may predate the development of senile plaques and neurofibrillary tangles in AD and may prove to be a more sensitive marker of prodromal AD. New developments in measuring CNS inflammation include measuring cytokine release by peripheral blood mononuclear cells and the development of PET markers of microglial activation. There is epidemiological evidence that circulating serum IL-6 is associated with poorer cognition. While epidemiological studies suggest a protective effect of NSAIDs against development of AD, controlled trials of NSAIDs to date have not shown any protective effect of drug. New anti-inflammatory agents for treating or preventing AD may include novel NSAIDs and opioid antagonists. These developments provide an alternative or potential adjunct to anti-amyloid therapies for AD.

Differential effects of COX inhibitors against β-amyloid-induced neurotoxicity in human neuroblastoma cells

Retrospective epidemiological studies have suggested that chronic treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) provides some degree of protection from Alzheimer's disease (AD). Although most NSAIDs inhibit the activity of cyclooxygenase (COX), the rate-limiting enzyme in the production of prostanoids from arachidonic acid (AA), the precise mechanism through which NSAIDs act upon AD pathology remains to be elucidated. Classical NSAIDs like indomethacin inhibit both the constitutive COX-1 and the inducible COX-2 enzymes. In the present work, we characterize the protective effect of the indomethacin on the neurotoxicity elicited by amyloid-beta protein (A beta, fragments 25-35 and 1-42) alone or in combination with AA added exogenously as well as its effects on COX-2 expression. We also compared the neuroprotective effects of indomethacin with the selective COX-1, COX-2 and 5-LOX inhibitors, SC-560, NS-398 and NDGA, respectively. Our results show that indomethacin protected from A beta and AA toxicity in naive and differentiated human neuroblastoma cells with more potency than SC-560 while, NS-398 only protected neurons from AA-mediated toxicity. Present results suggest that A beta toxicity can be reversed more efficiently by the non-selective COX inhibitor indomethacin suggesting its role in modulating the signal transduction pathway involved in the mechanism of A beta neurotoxicity.

Prostaglandin-induced neurodegeneration is associated with increased levels of oxidative markers and reduced by a mixture of antioxidants

Prostaglandin E2 (PGE2), one product of inflammatory reactions, and PGA1, which is formed during PGE2 extraction, induce degeneration in adenosine 3',5'-cyclic monophosphate (cAMP)-induced differentiated neuroblastoma (NB) cells in culture. The mechanisms of action of PGE2 on neurodegeneration are not well understood. To investigate this, we have utilized PGA(1), which mimics the effect of PGE2 and is very stable in solution. We have assayed selected markers of oxidative stress such as heme oxygenase-1 (HO-1), catalase, glutathione peroxidase (GPx1), mitochondrial superoxide dismutase (Mn-SOD-2) and cytosolic superoxide dismutase (Cu/Zn-SOD-1). The results showed that the treatment of differentiated NB cells with PGA1 for a period of 48 hr increased the expression of HO-1 and catalase, decreased the expression of GPx1 and Mn-SOD-2, and did not change the expression of Cu/Zn-SOD-1 as measured by gene array and confirmed by real-time PCR. The protein levels of HO-1 and GPx1 increased; however, the protein level of Mn-SOD-2 decreased and the levels of catalase and Cu/Zn-SOD-1 did not change as determined by Western blot. The increases in the levels of HO-1 and GPx1 reflected an adaptive response to increased oxidative stress, whereas decrease in the level of Mn-SOD-2 may make cells more sensitive to oxidative damage. These data suggest that one of the mechanisms of action of PGA1 on neurodegeneration may involve increased oxidative stress. This was supported further by the fact that a mixture of antioxidants (alpha-tocopherol, vitamin C, selenomethionine, and reduced glutathione), but not the individual antioxidants, reduced the level of PGA1-induced degeneration in differentiated NB cells. The addition of a single antioxidant at two or four times the concentration used in the mixture was toxic.

Curcumin inhibits the classical and the alternate pathways of complement activation

Curcumin (Cur), the golden yellow phenolic compound in turmeric, is well studied for its medicinal properties. In the current investigation, Cur dissolved using sodium hydroxide solution (CurNa) was tested for in vitro complement inhibitory activity and compared with rosmarinic acid (RA) and quercetin (Qur) dissolved using sodium hydroxide (RANa and QurNa, respectively) and the vaccinia virus complement control protein (VCP). The comparative study indicated that CurNa inhibited the classical complement pathway dose dependently (IC50 = 404 microM). CurNa was more active than RANa, but less active than QurNa. VCP was about 2,212, 2,786, and 4,520 times more active than QurNa, CurNa, and RANa, respectively. Further study revealed that CurNa dose dependently inhibited zymosan-induced activation of the alternate pathway of complement activation.

Post-training intrahippocampal infusion of nicotine prevents spatial memory retention deficits induced by the cyclo-oxygenase-2-specific inhibitor celecoxib in rats

Recently, we demonstrated that intrahippocampal infusion of the cyclo-oxygenase (COX)-2-specific inhibitor celecoxib impaired spatial memory retention in the Morris water maze. In the present work, we investigated the effects of nicotine, infused in the rat dorsal hippocampus several minutes after infusion of celecoxib, on memory retention in the Morris water maze. Rats were trained for 3 days; each day included two blocks, and each block contained four trials. Test trials were conducted 48 h after surgery. As expected, bilateral intrahippocampal infusion of celecoxib (19 microg/side; 0.1 m) increased escape latency and travel distance in rats, indicating significant impairment of spatial memory retention. We also examined the effects of bilateral infusion of nicotine (0.5, 1.0 and 2.0 microg/side) on memory retention. Infusion of 1 microg nicotine significantly decreased escape latency and travel distance but not swimming speed, compared with controls, suggesting memory retention enhancement by nicotine at this concentration. In separate experiments, bilateral infusion of nicotine, infused 5 min after 0.1 m (19 microg/side) celecoxib infusion, was associated with escape latency, travel distance and swimming speed profiles very similar to those in control animals. Brain tissue sections from several of these animals were subjected to immunohistochemical staining analysis with anti-COX-2 antibodies. Quantification analysis by optical density measurements showed that the celecoxib infusion reduced the immunoreactivity of COX-2-containing neurons in the CA1 area of the hippocampus compared with controls, although this reduction was not significant. However, infusion of a combination of celecoxib and nicotine significantly increased this immunoreactivity compared with levels in control and celecoxib-infused groups. These results suggest that nicotine prevented or reversed the adverse effects of celecoxib on spatial memory retention and protected or restored the immunostaining pattern of COX-2 neurons in the rat dorsal hippocampus.

Neuroinflammation: a potential therapeutic target

The increased appreciation of the importance of glial cell-propagated inflammation (termed 'neuroinflammation') in the progression of pathophysiology for diverse neurodegenerative diseases, has heightened interest in the rapid discovery of neuroinflammation-targeted therapeutics. Efforts include searches among existing drugs approved for other uses, as well as development of novel synthetic compounds that selectively downregulate neuroinflammatory responses. The use of existing drugs to target neuroinflammation has largely met with failure due to lack of efficacy or untoward side effects. However, the de novo development of new classes of therapeutics based on targeting selective aspects of glia activation pathways and glia-mediated pathophysiologies, versus targeting pathways of quantitative importance in non-CNS inflammatory responses, is yielding promising results in preclinical animal models. The authors briefly review selected clinical and preclinical data that reflect the prevailing approaches targeting neuroinflammation as a pathophysiological process contributing to onset or progression of neurodegenerative diseases. The authors conclude with opinions based on recent experimental proofs of concept using preclinical animal models of pathophysiology. The focus is on Alzheimer's disease, but the concepts are transferrable to other neurodegenerative disorders with an inflammatory component.

Mitochondrial inhibition and oxidative stress: reciprocating players in neurodegeneration

Although the etiology for many neurodegenerative diseases is unknown, the common findings of mitochondrial defects and oxidative damage posit these events as contributing factors. The temporal conundrum of whether mitochondrial defects lead to enhanced reactive oxygen species generation, or conversely, if oxidative stress is the underlying cause of the mitochondrial defects remains enigmatic. This review focuses on evidence to show that either event can lead to the evolution of the other with subsequent neuronal cell loss. Glutathione is a major antioxidant system used by cells and mitochondria for protection and is altered in a number of neurodegenerative and neuropathological conditions. This review also addresses the multiple roles for glutathione during mitochondrial inhibition or oxidative stress. Protein aggregation and inclusions are hallmarks of a number of neurodegenerative diseases. Recent evidence that links protein aggregation to oxidative stress and mitochondrial dysfunction will also be examined. Lastly, current therapies that target mitochondrial dysfunction or oxidative stress are discussed.

Update on cyclooxygenase inhibitors: has a third COX isoform entered the fray?

It has been more than 30 years since Sir John Vane first reported that the pharmacological actions of aspirin-like drugs could be explained by their ability to inhibit cyclooxygenase (COX). Since then, a second isoform of COX, named COX-2, has been discovered and highly selective inhibitors of this isoform have been marketed. Most recently, a splice variant of COX-1 mRNA, retaining intron 1, and given the names COX-3, COX-1b or COX-1v, has been described. Non-selective NSAIDs such as ibuprofen and naproxen, which inhibit both COX-1 and COX-2, have proven highly effective and safe in the short-term management of acute pain. Highly selective COX-2 inhibitors including celecoxib, rofecoxib, valdecoxib, lumiracoxib, and etoricoxib were developed with the hope of significantly reducing the serious gastrointestinal toxicities associated with chronic high-dose NSAID use. While long-term studies demonstrated that rofecoxib and lumiracoxib reduced the incidence of GI perforations, ulcerations and bleeds by approximately 60% compared to non-selective NSAIDs, recent reports also demonstrated that the chronic use of rofecoxib and celecoxib in arthritis and colorectal polyp patients, and the short-term use of parecoxib and valdecoxib in patients who had undergone coronary artery bypass surgery, resulted in a significant increase in serious cardiovascular events, including myocardial infarction and stroke compared to naproxen or placebo. COX-3 mRNA has been isolated in many tissues including canine and human cerebral cortex, human aorta, and rodent cerebral endothelium, heart, kidney and neuronal tissues. In transfected insect cells, canine COX-3 protein is expressed and was selectively inhibited by acetaminophen. However, in humans and rodents an acetaminophen sensitive COX-3 protein is not expressed because the retention of intron-1 adds 94 and 98 nucleotides to the COX-3 mRNA structure respectively. Since the genetic code is a triplicate code (3 nucleotides to form one amino acid), the retention of the intron in both species results in a frame shift in the RNA message and the production of a truncated protein with a completely different amino acid sequence than COX-1 or COX-2 lacking acetaminophen sensitivity. Advances made through a combination of basic molecular biological and pharmacological techniques, and well designed randomized controlled clinical trials have demonstrated that the apparent gastrointestinal advantage of selective COX-2 inhibitors appears to be outweighed by their potential for cardiovascular toxicity and that acetaminophen's analgesic and antipyretic effects do not involve the inhibition of the COX-1 splice variant protein, putative COX-3.

Role of inflammation in neurodegenerative diseases

PURPOSE OF REVIEW

Inflammation is a self-defensive reaction aimed at eliminating or neutralizing injurious stimuli, and restoring tissue integrity. In neurodegenerative diseases inflammation occurs as a local response driven by microglia, in the absence of leucocyte infiltration. Like peripheral inflammation, neuroinflammation may become a harmful process, and it is now widely accepted that it may contribute to the pathogenesis of many central nervous system disorders, including chronic neurodegenerative diseases. This review addresses some of the most recent advances in our understanding of neuroinflammation.

RECENT FINDINGS

The presence of activated microglia surrounding amyloid plaques and increased levels of complement elements, cytokines, chemokines and free radicals support the existence of a self-propagating toxic cycle and provide a rationale for anti-inflammatory approaches to prevent or delay neurodegeneration. Nonetheless, recent studies have provided evidence that chronic stimulation leads microglia to acquire an anti-inflammatory phenotype, characterized by activated morphology and induction of neuroprotective and immunoregulatory molecules. The causes and consequences of this atypical phenotype have just begun to be unravelled.

SUMMARY

Although significant advances have been made in our knowledge of degenerative diseases, there remains controversy regarding whether neuroinflammation and microglial activation are beneficial or detrimental. Strategies aimed at both preventing and boosting microglial activation are presently under investigation, and these studies might reveal new potentially effective treatments for these neurological disorders.

A randomized, double-blind, study of rofecoxib in patients with mild cognitive impairment

Inflammatory mechanisms have been implicated in Alzheimer's disease (AD) and might be mediated via the COX-2 enzyme. Previous studies with the selective COX-2 inhibitors, rofecoxib and celecoxib, have shown that they do not alter the progression of AD. We conducted a double-blind study to investigate whether rofecoxib could delay a diagnosis of AD in patients with mild cognitive impairment (MCI), a group with an expected annual AD diagnosis rate of 10-15%. MCI patients > or =65 years were randomized to rofecoxib 25 mg (N=725) or placebo (N=732) daily for up to 4 years. The primary end point was the percentage of patients with a clinical diagnosis of AD. The estimated annual AD diagnosis rate was lower than the anticipated 10-15%: 6.4% in the rofecoxib group vs 4.5% in the placebo group (rofecoxib : placebo hazard ratio=1.46 (95% CI: 1.09, 1.94), p=0.011). Analyses of secondary end points, including measures of cognition (eg the cognitive subscale of the AD Assessment Scale (ADAS-Cog)) and global function (eg the Clinical Dementia Rating (CDR)), did not demonstrate differences between treatment groups. There was also no consistent evidence that rofecoxib differed from placebo in post hoc analyses comparing ADAS-Cog and CDR-sum of boxes scores in overlapping subgroups of patients who had Mini Mental State Exam scores of 24-26 in the present MCI study and in a previous AD treatment study with a similar design. The results from this MCI study did not support the hypothesis that rofecoxib would delay a diagnosis of AD. In conjunction with the lack of effects observed in previous AD studies, the findings suggest that inhibition of COX-2 is not a useful therapeutic approach in AD.

Treatments for Alzheimer Disease

As our population ages, the incidence and prevalence of Alzheimer disease (AD) will increase dramatically. A number of therapies have been investigated for the treatment and prevention of AD. Clinicians should be prepared to provide evidence-based answers to inquiries regarding AD treatment. There is insufficient evidence to recommend ginkgo biloba, estrogen, statins, or nonsteroidal anti-inflammatory drugs for the prevention or treatment of AD. The use of vitamin E is supported by a single randomized controlled trial, while data on other antioxidants is mixed. There is good evidence that cholinesterase inhibitors and memantine are modestly effective in the treatment of AD. Cholinesterase inhibitors appear to be effective throughout the spectrum of AD, while memantine, alone or in combination with cholinesterase inhibitors, is effective in late stage disease. There is insufficient evidence to suggest superiority of one cholinesterase over another.

Budesonide epimer R, LAU-8080 and phenyl butyl nitrone synergistically repress cyclooxygenase-2 induction in [IL-1β+Aβ42]-stressed human neural cells

Interleukin-1beta (IL-1beta) and amyloid-beta peptide 42 (Abeta42) together induce a robust proinflammatory gene expression program in human neural cells in primary culture. One consistent genetic marker for this triggered inflammatory response is an increase in the expression of cycloooxygenase-2 (COX-2), a prostaglandin synthase also found to be up-regulated in neurological disorders such as Alzheimer's disease. In this study we provide data illustrating the combined effect of three independent classes of compounds: the glucocorticoid budesonide epimer R, the platelet-activating factor antagonist LAU-8080, and the free radical scavenger phenyl butyl nitrone, upon COX-2 gene activation and prostaglandin E2 (PGE2) levels in [IL-1beta+Abeta42]-stressed HN cells. The data indicate that specific combinations of repressors of COX-2 activity are synergistic in modulating the stress-induced up-regulation of COX-2 and PGE2, and this may be of potential therapeutic value in the design of treatment for complex neuroinflammatory disorders.

The role of inflammation in Alzheimer's disease

Considerable evidence gained over the past decade has supported the conclusion that neuroinflammation is associated with Alzheimer's disease (AD) pathology. Inflammatory components related to AD neuroinflammation include brain cells such as microglia and astrocytes, the classic and alternate pathways of the complement system, the pentraxin acute-phase proteins, neuronal-type nicotinic acetylcholine receptors (AChRs), peroxisomal proliferators-activated receptors (PPARs), as well as cytokines and chemokines. Both the microglia and astrocytes have been shown to generate beta-amyloid protein (Abeta), one of the main pathologic features of AD. Abeta itself has been shown to act as a pro-inflammatory agent causing the activation of many of the inflammatory components. Further substantiation for the role of neuroinflammation in AD has come from studies that demonstrate patients who took non-steroidal anti-inflammatory drugs had a lower risk of AD than those who did not. These same results have led to increased interest in pursuing anti-inflammatory therapy for AD but with poor results. On the other hand, increasing amount of data suggest that AChRs and PPARs are involved in AD-induced neuroinflammation and in this regard, future therapy may focus on their specific targeting in the AD brain.

Future directions in the treatment of Alzheimer’s disease

Alzheimer's disease (AD) remains the most common of the neurodegenerative disorders. In the elderly, it represents the most frequently occurring form of dementia, especially if considered alongside concomitant cerebrovascular disease. Current treatment involves the use of acetylcholinesterase inhibitors, which have shown symptomatic benefits in the recognised domains of cognition, function and behaviour. While they may have intrinsic disease-modifying activity, this is yet to be proven, and strategies to alter the fundamental neuropathological changes in AD continue to be sought. Much of the evidence suggests that the accumulation of amyloid-beta may play a pivotal role, therefore the bulk of current research is focused on possible intervention along the amyloid pathways. However, the abnormal phosphorylation of tau is also a reasonable target and as the molecular basis of AD is better delineated, more targeted treatment approaches are being proposed. This paper reports on the current data that is setting the future directions for research into AD.

The potential role of non-steroidal anti-inflammatory drugs in treating Alzheimer’s disease

Epidemiological studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer's disease (AD). Despite encouraging evidence, all large, long-term, placebo-controlled clinical trials aimed at reducing inflammation in the brain of AD patients produced negative results. More recently it has been shown that some NSAIDs decrease the production of amyloid-beta(1-42) (Abeta42), the major component of senile plaques of the AD brain, and counteract the progression of Abeta42 pathology in transgenic mouse models of AD. The proposed mechanism for this activity is an allosteric modulation of gamma-secretase activity, the enzyme responsible for the formation of amyloid-beta. The inhibition of Abeta42 production is independent from the anti-cyclooxygenase (COX) activity and is related to the chemical structure of the compounds, with some NSAIDs being active (ibuprofen, sulindac, flurbiprofen, indomethacin, diclofenac) and others not (naproxen, aspirin, celecoxib). This could explain the negative results of the large AD trials carried out so far, as they were conducted with compounds (naproxen, hydroxychloroquine, dapsone, prednisone, rofecoxib and celecoxib) that are not able to decrease Abeta42 production. Unfortunately, the use of these NSAIDs in AD is hampered by a significant gastrointestinal toxicity associated with COX inhibition. Thus, new NSAID analogues are being developed with potent and selective inhibitory activity on Abeta42 but with either lack of COX inhibitory activity or reduced gastrointestinal toxicity potential.

Rofecoxib attenuates both primary and secondary inflammatory hyperalgesia: a randomized, double blinded, placebo controlled crossover trial in the UV-B pain model

The analysis of drug's influence on peripheral and central sensitisation can give useful information about its mode of action and can lead to more efficacy in the treatment of pain. Peripheral inflammation is associated with peripheral expression and up-regulation of cyclooxygenase 2 (COX-2) in the CNS. The relative contribution of COX-2 mediated central sensitisation may be prominent under inflammatory conditions. In this randomized, double blinded, placebo controlled cross-over trial the effects of multidoses of the COX-2 selective inhibitor rofecoxib on primary and secondary hyperalgesia were evaluated in the UVB pain model. Twenty-four hours after local UVB irradiation at the upper leg of 42 healthy volunteers heat pain perception (HPPT) and heat pain tolerance thresholds (HPTT) were assessed within the inflammation. The area of secondary hyperalgesia was determined by pin prick test. Subjects received oral rofecoxib 50, 250, 500 mg or placebo. Pain testing was repeated after 3 and 6 h. Compared to placebo, rofecoxib significantly increased HPPT (1.55 and 1.08 degrees C, P<0.0001 and P=0.0333), HPTT (1.74 and 1.58 degrees C, P<0.0001 and P<0.0001), and reduced the mean area of secondary hyperalgesia by 15.6% (P=0.007) and 16.8% (P<0.001) after 3 and 6 h. No significant difference between the three dosage groups was observed. These data confirm peripheral effects of rofecoxib in a human inflammatory UV-B pain model and provide circumstantial evidence that even a standard clinical dose of rofecoxib reduces central hyperalgesia in inflammatory pain. We confirm that the effect of single oral dose of rofecoxib plateaus at 50 mg.

Activity of flurbiprofen and chemically related anti-inflammatory drugs in models of Alzheimer's disease

Currently, there is an intense debate on the potential use of nonsteroidal anti-inflammatory drugs (NSAIDs) in Alzheimer's disease (AD). NSAIDs are among the most widely prescribed drugs for the treatment of pain, fever, and inflammation. Their effects are largely attributed to the inhibition of the enzymatic activity of cyclooxygenase (COX)-1 and -2. The apparent activity of this class of drugs stems from one critical pathological process underlying AD and other neurodegenerative disorders, i.e., the presence of chronic neuroinflammation. In fact, prolonged use of NSAIDs is associated with reduced risk of AD. Besides COX inhibition, additional mechanisms could contribute to the potential activity of NSAIDs in AD. For example, several studies show that only a few selected NSAIDs also affect beta-amyloid (Abeta) deposition and metabolism. Among the Abeta-effective NSAIDs, flurbiprofen raised particular interest because of its multiple actions on key AD hallmarks. Studies in cell lines and animal models have shown that flurbiprofen racemate, its R-enantiomer and its nitric oxide (NO)-releasing derivatives, HCT 1026 and NCX 2216, are effective on AD amyloid pathology. Moreover, HCT 1026 and NCX 2216 differentially influence the cellular component of neuroinflammation (i.e., microglia activation) in some experimental settings, i.e., HCT 1026 inhibits the activation of microglia, while NCX 2216 can either enhance or inhibit microglial activation, depending upon the experimental conditions. It is still unclear which effects on microglia will prove most beneficial. Ultimately, clinical studies in AD patients will provide the best information as to whether selected NSAIDs will improve this devastating disease.

Molecular Rationale for the Pharmacological Treatment of Alzheimer??s Disease

Cerebral deposition of amyloid plaques containing amyloid beta-peptide (Abeta) has traditionally been considered the central feature of Alzheimer's disease (AD). Abeta is derived from amyloid precursor protein (APP), which is cleaved by several different proteases: alpha-, beta- and gamma-secretase. In the past decade, however, the molecular pathogenesis of AD has been shown to involve alterations in several neurotransmitter, inflammatory, oxidative, and hormonal pathways that represent potential targets for AD prevention and treatment. Much research has shown a direct link between cholinergic impairment and altered APP processing as a major pathogenetic event in AD. Three highly probable mechanisms of APP regulation through inhibition of acetylcholinesterase are thus current topics of investigation. Indeed, acetylcholinesterase inhibitors appear to cause selective muscarinic activation of alpha-secretase and to induce the translation of APP mRNA; they may also restrict amyloid fibre assembly. Activation of N-methyl-D-aspartate receptors is considered a probable cause of chronic neurodegeneration in AD, and memantine has been widely used in some countries in AD patients to block cerebral N-methyl-D-aspartate receptors that normally respond to glutamate. Further studies are needed to determine whether antioxidants such as vitamins C and E are effective, through various mechanisms, in patients with mild-to-moderate AD. Additional data are also required for non-steroidal anti-inflammatory drugs, some of which appear to possess experimental effects that may ultimately prove favourable in AD patients. Statins also warrant further investigation, since they have activated alpha-secretase and they reduced Abeta generation and amyloid accumulation in a transgenic mouse model. beta-Secretase would seem to be an ideal target for anti-amyloid therapy in AD, but potential clinical and pharmacological issues, such as ensuring selectivity of inhibition, stability, and ease of blood-brain barrier penetration and cellular uptake, remain to be addressed for beta-secretase inhibitors. gamma-Secretase is not an easy candidate for pharmacological manipulation. Immunotherapeutic strategies have targeted Abeta directly; however, intensive investigation of indirect approaches to the management of AD with immunotherapy is now underway.

Cognition, Function, and Caregiving Time Patterns in Patients With Mild-to-Moderate Alzheimer Disease

Placebo data were pooled from two 1-year, randomized, double-blind, placebo-controlled trials of sabeluzole in patients with mild-to-moderate Alzheimer disease (AD). Cognition was assessed using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and activities of daily living (ADL) with the Disability Assessment in Dementia (DAD). Time spent assisting with ADL was estimated according to the caregiver for each DAD domain in the 2 weeks before assessment. Progressive annual decline was seen on ADAS-cog (5.6 +/- 7.3 [mean +/- SD]) and DAD (-12.4 +/- 17.8), with greater decline in moderate patients (Mini-Mental State Examination [MMSE] < or =18) than mild patients (MMSE >18). An MMSE score of 16 appeared to be a key transition point at which most instrumental ADL were lost and major losses of basic ADL began to occur over the next 12 months. Caregivers spent, on average, 14 hours more assisting with ADL over 2 weeks at the end of 1 year. The proportion of care provided by paid caregivers increased relative to the time spent by informal caregivers. Patients with mild-to-moderate AD experience predictable annual decline in cognition and daily functioning, with measurably increased caregiver time. Small changes in ADAS-cog are nevertheless associated with a substantial measurable effect on the daily lives of both patients and caregivers.

Guidelines for the Treatment of Alzheimer??s Disease from the Italian Association of Psychogeriatrics

A committee of experts from the Italian Association of Psychogeriatrics compiled the following report, which was then approved by a Steering Committee (comprising 20 specialists in neurology, psychiatry or geriatrics) from the Association and by two Alzheimer associations representing patients and families: the Italian Association for Alzheimer's Disease and the Italian Federation for Alzheimer's Disease. The report is based on a comprehensive review of the scientific literature on the treatment of Alzheimer's disease, discusses methodological aspects of dementia management, and details the limitations of current therapies. These guidelines are, in general, consistent with the principles of evidence-based medicine; however, for some controversial or poorly investigated issues, the guidelines integrate scientific evidence with experience and opinions from experts working in the clinical setting. In particular, the clinical experience of experts has been used to define recommendations for starting and interrupting pharmacotherapy, and to critically review evidence about the efficacy of non-pharmacological interventions. The principal pharmacotherapeutic interventions covered in the guidelines are acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine, and tacrine) and memantine. The main non-pharmacological interventions reviewed are memory training, reality orientation therapy, and combined non-pharmacological interventions. Other issues covered are opportunities for Alzheimer's disease prevention, various modalities of care, and the treatment of comorbidities.

Modulation of nuclear factor-kappa B activity by indomethacin influences A beta levels but not A beta precursor protein metabolism in a model of Alzheimer's disease

Epidemiological studies show that some nonsteroidal anti-inflammatory drugs, nonspecific inhibitors of the cyclooxygenase enzyme, reduce the incidence of Alzheimer's disease (AD). We determined the impact of two nonsteroidal anti-inflammatory drugs on A beta levels, deposition, and metabolism in a mouse model (the Tg2576) of AD-like amyloidosis. To this end, mice were treated with indomethacin and nimesulide continuously from 8 months of age until they were 15 months old. At the end of the study, indomethacin significantly reduced A beta(1-40) and A beta(1-42) levels in both cortex and hippocampus. This decrease was coincidental with a significant reduction of the nuclear factor (NF)-kappa B activity. By contrast, nimesulide had no effect on both A beta peptides and NF-kappa B. Consistently, mice receiving indomethacin, but no nimesulide, showed a significant reduction in the amyloid burden compared with placebo. Neither drug had an effect on plasma levels of A beta peptides or the A beta precursor protein metabolism. In vitro studies confirmed that genetic absence of this factor reduces the anti-amyloidogenic effect of indomethacin. These findings indicate that chronic administration of indomethacin by blocking the activation of the NF-kappa B significantly reduces the amyloid pathology in Tg2576 mice, and provide insights into the mechanisms by which this drug could slow progression of AD.