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

The role of oestrogen therapy in reducing risk of Alzheimer's disease: systematic review

BACKGROUND

Studies have shown a relationship between oestrogen and Alzheimer's disease. However, there is neither clear nor strong evidence on the use of oestrogen-only therapy in reducing the risk of Alzheimer's disease.

AIMS

To assess the effects of oestrogen-only therapy on reducing the risk of Alzheimer's disease.

METHOD

Inclusion criteria was determined with the PICO framework. Outcome was cognitive function measured by neuropsychological tests and strict protocols. Exclusion criteria included non-Alzheimer's dementia, progesterone-only therapy and pre-menopausal women. Searches were conducted in nine electronic healthcare databases, last searched in July 2022. Quality assessments conducted on randomised controlled trials (RCTs) were performed with the GRADE assessment, and cohort studies and case-control studies were assessed with the Newcastle-Ottawa Scale. Extracted data were used to analyse participants, interventions and outcomes.

RESULTS

Twenty-four studies satisfied the search criteria (four RCTs, nine cohort studies, 11 case-control studies). Fifteen studies showed positive associations for oestrogen-only therapy reducing the risk of Alzheimer's disease, and the remaining nine found no evidence of association.

CONCLUSIONS

Fifteen studies showed that oestrogen-only therapy effectively reduced the risk of Alzheimer's disease, whereas nine showed no correlation. Studies also investigated oestrogen-related variables such as length of oestrogen exposure, being an apolipoprotein E ε4 carrier and concomitant use of non-steroidal anti-inflammatory drugs, and their role in neuroprotection. This review was limited by the limited ranges of duration of oestrogen treatment and type of oestrogen-only therapy used. In conclusion, oestrogen-only therapy has potential for use in preventing Alzheimer's disease, although current evidence is inconclusive and requires further study.

Versatile Synthesis of Organic Compounds Derived from Ascorbic Acid

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Ascorbic acid, also known as Vitamin C, is the most important vitamin observed in diverse food. Ascorbic acid has various applications in several fields. Studies have depicted that in organic synthesis, it can be used as a mediator or substrate. The derivatives of ascorbic acid have been found to possess numerous biological activities. In this review, we report the important derivatives of ascorbic acid, which have significant biological activities. Various studies are considered in this review to prove its wide range of availability.

Naproxen as a potential candidate for promoting rivastigmine anti-Alzheimer activity against aluminum chloride-prompted Alzheimer's-like disease in rats; neurogenesis and apoptosis modulation as a possible underlying mechanism

BACKGROUND AND AIM

Alzheimer's disease (AD) is one of the leading causes of dependence and disability among the elderly worldwide. The traditional anti-Alzheimer medication, rivastigmine, one of the cholinesterase inhibitors (ChEIs), fails to achieve a definitive cure. We tested the hypothesis that naproxen administration to the rivastigmine-treated aluminum chloride (AlCl3) Alzheimer's rat model could provide an additive neuroprotective effect compared to rivastigmine alone.

MATERIALS AND METHODS

The studied groups were control (Cont), AlCl3 treated (Al), rivastigmine treated (RIVA), naproxen treated (Napro), and combined rivastigmine and naproxen treated (RIVA + Napro). Rats' memory, spatial learning, and cognitive behavior were assessed followed by evaluation of hippocampal acetylcholinesterase (AChE) activity. Hippocampal and cerebellar histopathology were thoroughly examined. Activated caspase-3 and the neuroepithelial stem cells marker; nestin expressions were immunohistochemically assayed.

RESULTS

AD rats displayed significantly impaired memory and cognitive function, augmented hippocampal AChE activity; massive neurodegeneration associated with enhanced astrogliosis, apoptosis, and impaired neurogenesis. Except for the enhancement of neurogenesis and suppression of apoptosis, the combination therapy had no additional neuroprotective benefit over rivastigmine-only therapy.

CONCLUSION

Naproxen's efficacy was established by its ability to function at the cellular level, improved neurogenesis, and decreased, apoptosis without having an additional mitigating impact on cognitive impairment in rivastigmine-treated AD rats.

Inflammation: A Major Target for Compounds to Control Alzheimer's Disease

Several hypotheses have been postulated to explain how Alzheimer's disease is triggered, but none of them provide a unified view of its pathogenesis. The dominant hypothesis based on build-ups of the amyloid-β peptide has been around for longer than three decades; however, up to today, numerous clinical trials based on the amyloid postulates have been attempted, but all of them have failed. Clearly, the revisited tau hypothesis provides a better explanation of the clinical observations of patients, but it needs to integrate the cumulative observations on the onset of this disease. In this context, the neuroimmuno modulation theory, based on the involvement of inflammatory events in the central nervous system, accounts for all these observations. In this review we intend to emphasize the idea that neuroinflammation is a main target for the search of new therapeutic strategies to control Alzheimer's disease. Beyond mono-targeting approaches using synthetic drugs that control only specific pathophysiological events, emerging therapeutics views based on multi targeting compounds appear to provide a new pathway for Alzheimer's disease treatment.

Integrated communications between cyclooxygenase-2 and Alzheimer's disease

Elevated levels of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) are involved in the pathogenesis of Alzheimer's disease (AD), which is characterized by the accumulation of β-amyloid protein (Aβ) and tau hyperphosphorylation. However, the gaps in our knowledge of the roles of COX-2 and PGs in AD have not been filled. Here, we summarized the literature showing that COX-2 dysregulation obviously influences abnormal cleavage of β-amyloid precursor protein, aggregation and deposition of Aβ in β-amyloid plaques and the inclusion of phosphorylated tau in neurofibrillary tangles. Neuroinflammation, oxidative stress, synaptic plasticity, neurotoxicity, autophagy, and apoptosis have been assessed to elucidate the mechanisms of COX-2 regulation of AD. Notably, an imbalance of these factors ultimately produces cognitive decline. The current review substantiates our understanding of the mechanisms of COX-2-induced AD and establishes foundations for the design of feasible therapeutic strategies to treat AD.-Guan, P.-P., Wang, P. Integrated communications between cyclooxygenase-2 and Alzheimer's disease.

Synthesis of L-Ascorbyl Flurbiprofenate by Lipase-Catalyzed Esterification and Transesterification Reactions

The synthesis of L-ascorbyl flurbiprofenate was achieved by esterification and transesterification in nonaqueous organic medium with Novozym 435 lipase as biocatalyst. The conversion was greatly influenced by the kinds of organic solvents, speed of agitation, catalyst loading amount, reaction time, and molar ratio of acyl donor to L-ascorbic acid. A series of solvents were investigated, and tert-butanol was found to be the most suitable from the standpoint of the substrate solubility and the conversion for both the esterification and transesterification. When flurbiprofen was used as acyl donor, 61.0% of L-ascorbic acid was converted against 46.4% in the presence of flurbiprofen methyl ester. The optimal conversion of L-ascorbic acid was obtained when the initial molar ratio of acyl donor to ascorbic acid was 5 : 1. kinetics parameters were solved by Lineweaver-Burk equation under nonsubstrate inhibition condition. Since transesterification has lower conversion, from the standpoint of productivity and the amount of steps required, esterification is a better method compared to transesterification.

The role of serratiopeptidase in the resolution of inflammation

Inflammation remains a key event during most of the diseases and physiological imbalance. Acute inflammation is an essential physiological event by immune system for a protective measure to remove cause of inflammation and failure of resolution lead to chronic inflammation. Over a period of time, a number of drugs mostly chemical have been deployed to combat acute and chronic inflammation. Recently, enzyme based anti-inflammatory drugs became popular over conventional chemical based drugs. Serratiopeptidase, a proteolytic enzyme from trypsin family, possesses tremendous scope in combating inflammation. Serine protease possesses a higher affinity for cyclooxygenase (COX-I and COX-II), a key enzyme associated with production of different inflammatory mediators including interleukins (IL), prostaglandins (PGs) and thromboxane (TXs) etc. Currently, arthritis, sinusitis, bronchitis, fibrocystic breast disease, and carpal tunnel syndrome, etc. are the leading inflammatory disorders that affected the entire the globe. In order to conquer inflammation, both acute and chronic world, physician mostly relies on conventional drugs. The most common drugs to combat acute inflammation are Nonsteroidal anti-inflammatory drugs (NSAIDs) alone and or in combination with other drugs. However, during chronic inflammation, NSAIDs are often used with steroidal drugs such as autoimmune disorders. These drugs possess several limitations such as side effects, ADR, etc. In order to overcome these limitations and complications, enzyme based drugs (anti-inflammatory) emerged, and aim for a new high since the last decade. Serine protease, the largest proteolytic family has been reported for several therapeutic applications, including anti-inflammatory. Serratiopeptidase is a leading enzyme which has a very long history in medical as an effective anti-inflammatory drug. Current study emphasizes present scenario and future prospect of serratiopeptidase as an anti-inflammatory drug. The study also illustrates a comparative analysis of conventional drugs and enzyme based therapeutic to combat inflammation.

Prostaglandin I₂ Attenuates Prostaglandin E₂-Stimulated Expression of Interferon γ in a β-Amyloid Protein- and NF-κB-Dependent Mechanism

Cyclooxygenase-2 (COX-2) has been recently identified as being involved in the pathogenesis of Alzheimer's disease (AD). However, the role of an important COX-2 metabolic product, prostaglandin (PG) I2, in AD development remains unknown. Using mouse-derived astrocytes as well as APP/PS1 transgenic mice as model systems, we firstly elucidated the mechanisms of interferon γ (IFNγ) regulation by PGE2 and PGI2. Specifically, PGE2 accumulation in astrocytes activated the ERK1/2 and NF-κB signaling pathways by phosphorylation, which resulted in IFNγ expression. In contrast, the administration of PGI2 attenuated the effects of PGE2 on stimulating the production of IFNγ via inhibiting the translocation of NF-κB from the cytosol to the nucleus. Due to these observations, we further studied these prostaglandins and found that both PGE2 and PGI2 increased Aβ1-42 levels. In detail, PGE2 induced IFNγ expression in an Aβ1-42-dependent manner, whereas PGI2-induced Aβ1-42 production did not alleviate cells from IFNγ inhibition by PGI2 treatment. More importantly, our data also revealed that not only Aβ1-42 oligomer but also fibrillar have the ability to induce the expression of IFNγ via stimulation of NF-κB nuclear translocation in astrocytes of APP/PS1 mice. The production of IFNγ finally accelerated the deposition of Aβ1-42 in β-amyloid plaques.

No improvement after chronic ibuprofen treatment in the 5XFAD mouse model of Alzheimer's disease

Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that has been reported to reduce the risk of developing Alzheimer's disease (AD). Its preventive effects in AD are likely pleiotropic as ibuprofen displays both anti-inflammatory activity by inhibition of cyclooxygenases and anti-amyloidogenic activity by modulation of γ-secretase. In order to study the anti-inflammatory properties of ibuprofen independent of its anti-amyloidogenic activity, we performed a long-term treatment study with ibuprofen in 5XFAD mice expressing a presenilin-1 mutation that renders this AD model resistant to γ-secretase modulation. As expected, ibuprofen treatment for 3 months resulted in a reduction of the inflammatory reaction in the 5XFAD mouse model. Importantly, an unchanged amyloid beta (Aβ) plaque load, an increase in soluble Aβ42 levels, and an aggravation of some behavioral parameters were noted, raising the question whether suppression of inflammation by nonsteroidal anti-inflammatory drug is beneficial in AD.

Naproxen interferes with the assembly of Aβ oligomers implicated in Alzheimer's disease

Experimental and epidemiological studies have shown that the nonsteroidal antiinflammatory drug naproxen may be useful in the treatment of Alzheimer's disease. To investigate the interactions of naproxen with Aβ dimers, which are the smallest cytotoxic aggregated Aβ peptide species, we use united atom implicit solvent model and exhaustive replica exchange molecular dynamics. We show that naproxen ligands bind to Aβ dimer and penetrate its volume interfering with the interpeptide interactions. As a result naproxen induces a destabilizing effect on Aβ dimer. By comparing the free-energy landscapes of naproxen interactions with Aβ dimers and fibrils, we conclude that this ligand has stronger antiaggregation potential against Aβ fibrils rather than against dimers. The analysis of naproxen binding energetics shows that the location of ligand binding sites in Aβ dimer is dictated by the Aβ amino acid sequence. Comparison of the in silico findings with experimental observations reveals potential limitations of naproxen as an effective therapeutic agent in the treatment of Alzheimer's disease.

Are NSAIDs useful to treat Alzheimer's disease or mild cognitive impairment?

Several epidemiological studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) may protect subjects carrying one or more ε4 allele of the apolipoprotein E (APOE ε4) against the onset of Alzheimer's disease (AD). The biological mechanism of this protection is not completely understood and may involve the anti-inflammatory properties of NSAIDs or their ability of interfering with the β-amyloid (Aβ) cascade. Unfortunately, long-term, placebo-controlled clinical trials with both non-selective and cyclooxygenase-2 (COX-2) selective inhibitors in mild-to-moderate AD patients produced negative results. A secondary prevention study with rofecoxib, a COX-2 selective inhibitor, in patients with mild cognitive impairment was also negative. A primary prevention study (ADAPT trial) of naproxen (a non-selective COX inhibitor) and celecoxib (a COX-2 selective inhibitor) in cognitively normal elderly subjects with a family history of AD was prematurely interrupted for safety reasons after a median period of treatment of 2 years. Although both drugs did not reduce the incidence of dementia after 2 years of treatment, a 4-year follow-up assessment surprisingly revealed that subjects previously exposed to naproxen were protected from the onset of AD by 67% compared to placebo. Thus, it could be hypothesized that the chronic use of NSAIDs may be beneficial only in the very early stages of the AD process in coincidence of initial Aβ deposition, microglia activation and consequent release of pro-inflammatory mediators. When the Aβ deposition process is already started, NSAIDs are no longer effective and may even be detrimental because of their inhibitory activity on chronically activated microglia that on long-term may mediate Aβ clearance. The research community should conduct long-term trials with NSAIDs in cognitively normal APOE ε4 carriers.

Disease-modifying approach to the treatment of Alzheimer's disease: from alpha-secretase activators to gamma-secretase inhibitors and modulators

In the last decade, advances in understanding the neurobiology of Alzheimer's disease (AD) have translated into an increase in clinical trials assessing various potential AD treatments. At present, drugs used for the treatment of AD only slightly delay the inevitable symptomatic progression of the disease and do not affect the main neuropathological hallmarks of the disease, i.e. senile plaques and neurofibrillary tangles. Brain accumulation of oligomeric species of beta-amyloid (A beta) peptides, the principal components of senile plaques, is believed to play a crucial role in the development of AD. Based on this hypothesis, huge efforts are being made to identify drugs able to interfere with proteases regulating A beta formation from amyloid precursor protein (APP). Compounds that stimulate alpha-secretase, the enzyme responsible for non-amyloidogenic metabolism of APP, are being developed and one of these, EHT-0202, has recently commenced evaluation in a phase II study. The discovery of inhibitors of beta-secretase (memapsin-2, beta-amyloid cleaving enzyme-1 [BACE-1]), the enzyme that regulates the first step of amyloidogenic APP metabolism, has proved to be particularly difficult because of inherent medicinal chemistry issues and only one compound (CTS-21166) has proceeded to clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates A beta, have been identified, the most advanced being LY-450139 (semagacestat), presently in phase III clinical development. There has been considerable disappointment over the failure of a phase III study of tarenflurbil, a compound believed to modulate the activity of gamma-secretase, after encouraging phase II findings. Nevertheless, other promising gamma-secretase modulators are being developed and are approaching clinical testing. All these therapeutic approaches increase the hope of slowing the rate of decline in patients with AD and modifying the natural history of this devastating disease within the next 5 years.

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.

Molecular dynamics simulations of Ibuprofen binding to Abeta peptides

Using replica exchange molecular dynamics simulations and the implicit solvent model we probed binding of ibuprofen to Abeta(10-40) monomers and amyloid fibrils. We found that the concave (CV) fibril edge has significantly higher binding affinity for ibuprofen than the convex edge. Furthermore, binding of ibuprofen to Abeta monomers, as compared to fibrils, results in a smaller free energy gain. The difference in binding free energies is likely to be related to the presence of the groove on the CV fibril edge, in which ibuprofen tends to accumulate. The confinement effect of the groove promotes the formation of large low-energy ibuprofen clusters, which rarely occur on the surface of Abeta monomers. These observations led us to suggest that the ibuprofen binding mechanism for Abeta fibrils is different from that for monomers. In general, ibuprofen shows a preference to bind to those regions of Abeta monomers (amino terminal) and fibrils (the CV edge) that are also the primary aggregation interfaces. Based on our findings and on available experimental data, we propose a rationale for the ibuprofen antiaggregation effect.

Beyond the neurotransmitter-focused approach in treating Alzheimer's disease: drugs targeting beta-amyloid and tau protein

Drugs currently used to treat Alzheimer's Disease (AD) have limited therapeutic value and do not affect the main neuropathological hallmarks of the disease, i.e., senile plaques and neurofibrillar tangles. Senile plaques are mainly formed of beta-amyloid (Abeta), a 42-aminoacid peptide. Neurofibrillar tangles are composed of paired helical filaments of hyperphosphorylated tau protein. New, potentially disease-modifying, therapeutic approaches are targeting Abeta and tau protein. Drugs directed against Abeta include active and passive immunization, that have been found to accelerate Abeta clearance from the brain. The most developmentally advanced monoclonal antibody directly targeting Abeta is bapineuzumab, now being studied in a large Phase III clinical trial. Compounds that interfere with proteases regulating Abeta formation from amyloid precursor protein (APP) are also actively pursued. The discovery of inhibitors of beta-secretase, the enzyme that regulates the first step of the amyloidogenic metabolism of APP, has been revealed to be particularly difficult due to inherent medicinal chemistry problems, and only one compound (CTS-21166) has reached clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates Abeta, have been identified, the most advanced being LY-450139 (semagacestat), now in Phase III clinical development. Compounds that stimulate alpha-secretase, the enzyme responsible for the non-amyloidogenic metabolism of APP, are also being developed, and one of them, EHT-0202, has recently entered Phase II testing. Potent inhibitors of Abeta aggregation have also been identified, and one of such compounds, PBT-2, has provided encouraging neuropsychological results in a recently completed Phase II study. Therapeutic approaches directed against tau protein include inhibitors of glycogen synthase kinase- 3 (GSK-3), the enzyme responsible for tau phosphorylation and tau protein aggregation inhibitors. NP-12, a promising GSK-3 inhibitor, is being tested in a Phase II study, and methylthioninium chloride, a tau protein aggregation inhibitor, has given initial encouraging results in a 50-week study. With all these approaches on their way, the hope for disease-modifying therapy in this devastating disease may become a reality in the next 5 years.

Pharmacological Treatment of Alzheimer's Disease: Is it Progressing Adequately?

INTRODUCTION

Between 1993 and 2000 four acetylcholinesterase inhibitors were marketed as a symptomatic treatment for Alzheimer's disease (AD), as well as memantine in 2003. Current research is focused on finding drugs that favorably modify the course of the disease. However, their entrance into the market does not seem to be imminent.

RESEARCH DEVELOPMENT

The aim of AD research is to find substances that inhibit certain elements of the AD pathogenic chain (beta- and gamma-secretase inhibitors, alpha-secretase stimulants, beta-amyloid aggregability reducers or disaggregation and elimination inductors, as well as tau-hyperphosphorylation, glutamate excitotoxicity, oxidative stress and mitochondrial damage reducers, among other action mechanisms). Demonstrating a disease's retarding effect demands longer trials than those necessary to ascertain symptomatic improvement. Besides, a high number of patients (thousands of them) is necessary, all of which turns out to be difficult and costly. Furthermore, it would be necessary to count on diagnosis and progression markers in the disease's pre-clinical stage, markers for specific phenotypes, as well as high-selectivity molecules acting only where necessary. In order to compensate these difficulties, drugs acting on several defects of the pathogenic chain or showing both symptomatic and neuroprotective action simultaneously are being researched.

CONCLUSIONS

There are multiple molecules used in research to modify AD progression. Although it turns out to be difficult to obtain drugs with sufficient efficacy so that their marketing is approved, if they were achieved they would lead to a reduction of AD prevalence.

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.

Ibuprofen reduces Abeta, hyperphosphorylated tau and memory deficits in Alzheimer mice

We examined the effects of ibuprofen on cognitive deficits, Abeta and tau accumulation in young triple transgenic (3xTg-AD) mice. 3xTg-AD mice were fed ibuprofen-supplemented chow between 1 and 6 months. Untreated 3xTg-AD mice showed significant impairment in the ability to learn the Morris water maze (MWM) task compared to age-matched wild-type (WT) mice. The performance of 3xTg-AD mice was significantly improved with ibuprofen treatment compared to untreated 3xTg-AD mice. Ibuprofen-treated transgenic mice showed a significant decrease in intraneuronal oligomeric Abeta and hyperphosphorylated tau (AT8) immunoreactivity in the hippocampus. Confocal microscopy demonstrated co-localization of conformationally altered (MC1) and early phosphorylated tau (CP-13) with oligomeric Abeta, and less co-localization of oligomeric Abeta and later forms of phosphorylated tau (AT8 and PHF-1) in untreated 3xTg-AD mice. Our findings show that prophylactic treatment of young 3xTg-AD mice with ibuprofen reduces intraneuronal oligomeric Abeta, reduces cognitive deficits, and prevents hyperphosphorylated tau immunoreactivity. These findings provide further support for intraneuronal Abeta as a cause of cognitive impairment, and suggest that pathological alterations of tau are associated with intraneuronal oligomeric Abeta accumulation.

Dual roles of NF-kappaB in cell survival and implications of NF-kappaB inhibitors in neuroprotective therapy

NF-kappaB is a well-characterized transcription factor with multiple physiological and pathological functions. NF-kappaB plays important roles in the development and maturation of lymphoids, regulation of immune and inflammatory response, and cell death and survival. The influence of NF-kappaB on cell survival could be protective or destructive, depending on types, developmental stages of cells, and pathological conditions. The complexity of NF-kappaB in cell death and survival derives from its multiple roles in regulating the expression of a broad array of genes involved in promoting cell death and survival. The activation of NF-kappaB has been found in many neurological disorders, but its actual roles in pathogenesis are still being debated. Many compounds with neuroprotective actions are strongly associated with the inhibition of NF-kappaB, leading to speculation that blocking the pathological activation of NF-kappaB could offer neuroprotective effects in certain neurodegenerative conditions. This paper reviews the recent developments in understanding the dual roles of NF-kappaB in cell death and survival and explores its possible usefulness in treating neurological diseases. This paper will summarize the genes regulated by NF-kappaB that are involved in cell death and survival to elucidate why NF-kappaB promotes cell survival in some conditions while facilitating cell death in other conditions. This paper will also focus on the effects of various NF-kappaB inhibitors on neuroprotection in certain pathological conditions to speculate if NF-kappaB is a potential target for neuroprotective therapy.

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.

Comparison of biochemical effects of statins and fish oil in brain: the battle of the titans

Neural membranes are composed of glycerophospholipids, sphingolipids, cholesterol and proteins. The distribution of these lipids within the neural membrane is not random but organized. Neural membranes contain lipid rafts or microdomains that are enriched in sphingolipids and cholesterol. These rafts act as platforms for the generation of glycerophospholipid-, sphingolipid-, and cholesterol-derived second messengers, lipid mediators that are necessary for normal cellular function. Glycerophospholipid-derived lipid mediators include eicosanoids, docosanoids, lipoxins, and platelet-activating factor. Sphingolipid-derived lipid mediators include ceramides, ceramide 1-phosphates, and sphingosine 1-phosphate. Cholesterol-derived lipid mediators include 24-hydroxycholesterol, 25-hydroxycholesterol, and 7-ketocholesterol. Abnormal signal transduction processes and enhanced production of lipid mediators cause oxidative stress and inflammation. These processes are closely associated with the pathogenesis of acute neural trauma (stroke, spinal cord injury, and head injury) and neurodegenerative diseases such as Alzheimer disease. Statins, the HMG-CoA reductase inhibitors, are effective lipid lowering agents that significantly reduce risk for cardiovascular and cerebrovascular diseases. Beneficial effects of statins in neurological diseases are due to their anti-excitotoxic, antioxidant, and anti-inflammatory properties. Fish oil omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have similar anti-excitotoxic, antioxidant and anti-inflammatory effects in brain tissue. Thus the lipid mediators, resolvins, protectins, and neuroprotectins, derived from eicosapentaenoic acid and docosahexaenoic acid retard neuroinflammation, oxidative stress, and apoptotic cell death in brain tissue. Like statins, ingredients of fish oil inhibit generation of beta-amyloid and provide protection from oxidative stress and inflammatory processes. Collective evidence suggests that antioxidant, anti-inflammatory, and anti-apoptotic properties of statins and fish oil contribute to the clinical efficacy of treating neurological disorders with statins and fish oil. We speculate that there is an overlap between neurochemical events associated with neural cell injury in stroke and neurodegenerative diseases. This commentary compares the neurochemical effects of statins with those of fish oil.

Disease-modifying therapies in Alzheimer's disease: how far have we come?

Currently, there are no disease-modifying therapies available for Alzheimer's disease (AD). Acetylcholinesterase inhibitors and memantine are licensed for AD and have moderate symptomatic benefits. Epidemiological studies have suggested that NSAIDs, estrogen, HMG-CoA reductase inhibitors (statins) or tocopherol (vitamin E) can prevent AD. However, prospective, randomised studies have not convincingly been able to demonstrate clinical efficacy. Major progress in molecular medicine suggests further drug targets. The metabolism of the amyloid-precursor protein and the aggregation of its Abeta fragment are the focus of current studies. Abeta peptides are produced by the enzymes beta- and gamma-secretase. Inhibition of gamma-secretase has been shown to reduce Abeta production. However, gamma-secretase activity is also involved in other vital physiological pathways. Involvement of gamma-secretase in cell differentiation may preclude complete blockade of gamma-secretase for prolonged times in vivo. Inhibition of beta-secretase seems to be devoid of serious adverse effects according to studies with knockout animals. However, targeting beta-secretase is hampered by the lack of suitable inhibitors to date. Other approaches focus on enzymes that cut inside the Abeta sequence such as alpha-secretase and neprilysin. Stimulation of the expression or activity of alpha-secretase or neprilysin has been shown to enhance Abeta degradation. Furthermore, inhibitors of Abeta aggregation have been described and clinical trials have been initiated. Peroxisome proliferator activated receptor-gamma agonists and selected NSAIDs may be suitable to modulate both Abeta production and inflammatory activation. On the basis of autopsy reports, active immunisation against Abeta in humans seems to have proven its ability to clear amyloid deposits from the brain. However, a first clinical trial with active vaccination against the full length Abeta peptide has been halted because of adverse effects. Further trials with vaccination or passive transfer of antibodies are planned.

Modulation of inflammation in brain: a matter of fat

Neuroinflammation is a host defense mechanism associated with neutralization of an insult and restoration of normal structure and function of brain. Neuroinflammation is a hallmark of all major CNS diseases. The main mediators of neuroinflammation are microglial cells. These cells are activated during a CNS injury. Microglial cells initiate a rapid response that involves cell migration, proliferation, release of cytokines/chemokines and trophic and/or toxic effects. Cytokines/chemokines stimulate phospholipases A2 and cyclooxygenases. This results in breakdown of membrane glycerophospholipids with the release of arachidonic acid (AA) and docosahexaenoic acid (DHA). Oxidation of AA produces pro-inflammatory prostaglandins, leukotrienes, and thromboxanes. One of the lyso-glycerophospholipids, the other products of reactions catalyzed by phospholipase A2, is used for the synthesis of pro-inflammatory platelet-activating factor. These pro-inflammatory mediators intensify neuroinflammation. Lipoxin, an oxidized product of AA through 5-lipoxygenase, is involved in the resolution of inflammation and is anti-inflammatory. Docosahexaenoic acid is metabolized to resolvins and neuroprotectins. These lipid mediators inhibit the generation of prostaglandins, leukotrienes, and thromboxanes. Levels of prostaglandins, leukotrienes, and thromboxanes are markedly increased in acute neural trauma and neurodegenerative diseases. Docosahexaenoic acid and its lipid mediators prevent neuroinflammation by inhibiting transcription factor NFkappaB, preventing cytokine secretion, blocking the synthesis of prostaglandins, leukotrienes, and thromboxanes, and modulating leukocyte trafficking. Depending on its timing and magnitude in brain tissue, inflammation serves multiple purposes. It is involved in the protection of uninjured neurons and removal of degenerating neuronal debris and also in assisting repair and recovery processes. The dietary ratio of AA to DHA may affect neurodegeneration associated with acute neural trauma and neurodegenerative diseases. The dietary intake of docosahexaenoic acid offers the possibility of counter-balancing the harmful effects of high levels of AA-derived pro-inflammatory lipid mediators.

Increased isoprostane and prostaglandin are prominent in neurons in Alzheimer disease

BACKGROUND

Inflammation and oxidative stress are both involved in the pathogenesis of Alzheimer disease and have been shown to be reciprocally linked. One group of molecules that have been directly associated with inflammation and the production of free radicals are the prostaglandin 13,14-dihydro 15-keto PGF2alpha and the isoprostane 8-iso-PGF2alpha.

RESULTS

To further delineate the role of inflammatory and oxidative parameters in Alzheimer disease, in this study we evaluated the amount and localization of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in hippocampal post mortem tissue samples from age-matched Alzheimer disease and control patients. Our results demonstrate increased levels of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in the hippocampal pyramidal neurons of Alzheimer disease patients when compared to control patients.

CONCLUSION

These data not only support the shared mechanistic involvement of free radical damage and inflammation in Alzheimer disease, but also indicate that multiple pathogenic "hits" are likely necessary for both the development and propagation of Alzheimer disease.

In vitro and in vivo profiling of CHF5022 and CHF5074 Two beta-amyloid1-42 lowering agents

Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) may delay or prevent the onset of Alzheimer's disease (AD). A subset of NSAIDs, including flurbiprofen, has been shown to selectively inhibit the production of beta-amyloid(1-42) (Abeta42), independently from their cyclooxygenase (COX) inhibiting activity. We evaluated the in vitro and in vivo profiles of CHF5022 and CHF5074, two flurbiprofen analogues. The in vitro Abeta inhibiting activity was evaluated in a human neuroglioma cell line (H4) carrying the double Swedish mutation (K595N/M596L) of the human amyloid precursor protein (APPsw). The in vitro anti-COX activity was evaluated using human recombinant enzymes isolated from transfected Sf-9 cells. The in vivo pharmacokinetic and pharmacodynamic profiles of the two compounds were evaluated in young APPsw transgenic mice (Tg2576) after oral gavage (100 or 300mgkg(-1) day(-1) for 4-5 days) and after medicated diet (375ppm for 4 weeks). R-Flurbiprofen was used as comparator. In vitro, CHF5022 and CHF5074 were found to be 3- and 7-fold more potent than R-flurbiprofen in inhibiting Abeta42 secretion (IC(50)s of 92, 40 and 268microM, respectively). Differently from R-flurbiprofen, CHF5022 and CHF5074 did not affect COX-1 (at 100microM) and COX-2 (at 300microM) activity. Similarly to R-flurbiprofen, no significant alteration in the expression profile of a subset of Notch intracellular domain-responsive genes was observed with either CHF5022 or CHF5074. In Tg2576 mice, CHF5022 was well tolerated when administered by oral gavage (100mgkg(-1) day(-1) for 5 days) or by medicated diet (56mg kg(-1) day(-1) for 4 weeks). R-Flurbiprofen was poorly tolerated in the diet (32mgkg(-1) day(-1)) with 55% of the animals dying during the first week of treatment. After 4-5 days of oral gavage, CHF5022 and CHF5074 plasma and brain levels at 3h were found to increase with the dose, leading to brain concentrations of about 10% and 5% of the corresponding plasma concentrations, respectively. In animals fed for 4 weeks with compound-supplemented diet, mean plasma (580microM) and brain (20microM) Cyrillic) concentrations of CHF5022 were 8 and 15 times higher than those of R-flurbiprofen. Plasma Abeta42 concentration was dose-dependently decreased by CHF5022 and CHF5074. Brain Abeta levels (formic acid-extractable) were not significantly affected by either compound, although Abeta42 levels tended to inversely correlate (P=0.105) with CHF5022 concentration in the brain. CHF5022 and CHF5074 thus appear to have a promising in vitro and in vivo profile. This warrants further evaluation of their long-term effects on Abeta brain pathology.

An update on pharmacological approaches to neurodegenerative diseases

Neurodegenerative diseases are now generally considered as a group of disorders that seriously and progressively impair the functions of the nervous system through selective neuronal vulnerability of specific brain regions. Alzheimer's disease is the most common neurodegenerative disease, followed in incidence by Parkinson's disease; much less common are frontotemporal dementia, Huntington's disease, amyothrophic lateral sclerosis (Lou Gehrig's disease), progressive supranuclear palsy, spinocerebellar ataxia, Pick's disease and, lastly, prion disease. In this review, the authors intend to survey new drugs in different clinical phases but not in the preclinical or discovery stages nor already in the market, with new molecules aimed at interrupting or at attenuating different pathogenic pathways of neurodegeneration and/or at ameliorating symptoms. Drugs in different pharmacological phases are under study or are ready to be introduced into therapy for Alzheimer's disease, which display anti-beta-amyloid activity or nerve growth factor-like activity or anti-inflammatory properties. Other drugs possess mixed mechanisms of action, such as acetylcholinesterase inhibition and impairment of beta-amyloid formation through inhibition of beta-amyloid precursor protein synthesis and/or modulation of secretase activity. Other therapeutic approaches are based on immunotherapy, control of metal ions interactions with beta-amyloid and ensuing oxidative reactions as well as metabolic or hormonal regulation. The symptomatic therapy of motor behaviour in Parkinson's disease, based on l-DOPA, is registering adenosine A(2A) receptor antagonists, monoamine oxidase B inhibitors and ion channel modulators, as well as dopamine uptake inhibitors and glutamate AMPA receptor antagonists. There are also many other drugs involved, including astrocyte-modulating agents, 5-HT(1A) agonists and alpha(2)-adrenergic receptor antagonists, which are targeted at preventing or ameliorating Parkinson's disease-related or l-DOPA-induced dyskinesias. Huntington's disease therapy envisages a Phase III drug, LAX-101, which displays antiapoptotic properties by promoting membrane stabilisation and mitochondrial integrity. Other drugs with antioxidant and antiapoptotic steroid-like and neuroprotective activity are under investigation for the therapy of the less common neurodegenerative diseases.

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.

γ-Secretase Modulation with Aβ42-Lowering Nonsteroidal Anti-Inflammatory Drugs and Derived Compounds

The amyloid-beta (Abeta) peptides and specifically the highly amyloidogenic isoform Abeta42 appear to be key agents in the pathogenesis of familial and sporadic forms of Alzheimer's disease (AD). The final step in the generation of Abeta from the amyloid precursor protein is catalyzed by the multiprotein complex gamma-secretase, which constitutes a prime drug target for prevention and therapy of the disease. However, highly potent gamma-secretase inhibitors that block formation of all Abeta peptides have provoked troubling side effects in preclinical animal models of AD. This toxicity can be readily explained by the promiscuous substrate specificity of gamma-secretase and its essential role in the NOTCH signaling pathway. For that reason and because of the crucial role of Abeta42 in the pathogenesis of the disease, selective inhibition of Abeta42 production would seem to be a more promising alternative to complete inhibition of gamma-secretase activity. This theoretical concept has edged much closer to clinical reality with the surprising finding that certain nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, and derived compounds display preferential Abeta42-lowering activity. In contrast to gamma-secretase inhibitors, these gamma-secretase modulators effectively suppress Abeta42 production while sparing processing of NOTCH and other gamma-secretase substrates. Although not fully resolved on the molecular level, the mechanism of action of Abeta42-lowering NSAIDs is independent of cyclooxygenase inhibition and most likely involves direct interaction with components of the gamma-secretase complex or its substrates. Current efforts to improve the pharmacological shortcomings of available gamma-secretase modulators will hopefully lead to the development of clinically useful Abeta42-lowering compounds in the near future.

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.

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.

Synthesis and biological activity of flurbiprofen analogues as selective inhibitors of beta-amyloid(1)(-)(42) secretion

Flurbiprofen, a nonsteroidal antiinflammatory drug (NSAID), has been recently described to selectively inhibit beta-amyloid(1)(-)(42) (Abeta42) secretion, the most toxic component of the senile plaques present in the brain of Alzheimer patients. The use of this NSAID in Alzheimer's disease (AD) is hampered by a significant gastrointestinal toxicity associated with cyclooxygenase (COX) inhibition. New flurbiprofen analogues were synthesized, with the aim of increasing Abeta42 inhibitory potency while removing anti-COX activity. In vitro ADME developability parameters were taken into account in order to identify optimized compounds at an early stage of the project. Appropriate substitution patterns at the alpha position of flurbiprofen allowed for the complete removal of anti-COX activity, while modifications at the terminal phenyl ring resulted in increased inhibitory potency on Abeta42 secretion. In rats, some of the compounds appeared to be well absorbed after oral administration and to penetrate into the central nervous system. Studies in a transgenic mice model of AD showed that selected compounds significantly decreased plasma Abeta42 concentrations. These new flurbiprofen analogues represent potential drug candidates to be developed for the treatment of AD.