Cyclooxygenase and inflammation in Alzheimer's disease: experimental approaches and clinical interventions

Assessment of Pharmacological Potential of Novel Exopolysaccharide Isolated from Marine Kocuria sp. Strain AG5: Broad-Spectrum Biological Investigations

With more than 17 clinically approved Drugs and over 20 prodrugs under clinical investigations, marine bacteria are believed to have a potential supply of innovative therapeutic bioactive compounds. In the current study, Kocuria sp. strain AG5 isolated from the Red Sea was identified and characterized by biochemical and physiological analysis, and examination of a phylogenetic 16S rRNA sequences. Innovative exopolysaccharide (EPS) was separated from the AG5 isolate as a major fraction of EPS (EPSR5, 6.84 g/L⁻¹). The analysis of EPSR5 revealed that EPSR5 has a molecular weight (Mw) of 4.9 × 10⁴ g/mol and number average molecular weight (Mn) of 5.4 × 10⁴ g/mol and contains sulfate (25.6%) and uronic acid (21.77%). Analysis of the monosaccharide composition indicated that the EPSR5 fraction composes of glucose, galacturonic acid, arabinose, and xylose in a molar ratio of 2.0:0.5:0.25:1.0, respectively. Assessment of the pharmacological potency of EPSR5 was explored by examining its cytotoxicity, anti-inflammatory, antioxidant, and anti-acetylcholine esterase influences. The antioxidant effect of EPSR5 was dose- and time-dependently increased and the maximum antioxidant activity (98%) was observed at 2000 µg/mL after 120 min. Further, EPSR5 displayed a significant repressive effect regarding the proliferation of HepG-2, A-549, HCT-116, MCF7, HEP2, and PC3 cells with IC₅₀ 453.46 ± 21.8 µg/mL, 873.74 ± 15.4 µg/mL, 788.2 ± 32.6 µg/mL, 1691 ± 44.2 µg/mL, 913.1 ± 38.8 µg/mL, and 876.4 ± 39.8 µg/mL, respectively. Evaluation of the inhibitory activity of the anti-inflammatory activity of EPSR5 indicated that EPSR5 has a significant inhibitory activity toward lipoxygenase (5-LOX) and cyclooxygenase (COX-2) activities (IC₅₀ 15.39 ± 0.82 µg/mL and 28.06 ± 1.1 µg/mL, respectively). Finally, ESPR5 presented a substantial hemolysis suppressive action with an IC₅₀ of 65.13 ± 0.89 µg /mL, and a considerable inhibitory activity toward acetylcholine esterase activity (IC₅₀ 797.02 μg/mL). Together, this study reveals that secondary metabolites produced by Kocuria sp. strain AG5 marine bacteria serve as an important source of pharmacologically active compounds, and their impact on human health is expected to grow with additional global work and research.

Novel Exopolysaccharide from Marine Bacillus subtilis with Broad Potential Biological Activities: Insights into Antioxidant, Anti-Inflammatory, Cytotoxicity, and Anti-Alzheimer Activity

In the presented study, Bacillus subtilis strain AG4 isolated from marine was identified based on morphological, physiological, phylogenetic characteristics and an examination of 16S rRNA sequences. Novel exopolysaccharide (EPSR4) was extracted and isolated from the Bacillus subtilis strain as a major fraction of exopolysaccharide (EPS). The analysis of structural characterization indicated that EPSR4 is a β-glycosidic sulphated heteropolysaccharide (48.2%) with a molecular weight (Mw) of 1.48 × 104 g/mole and has no uronic acid. Analysis of monosaccharide content revealed that EPSR4 consists of glucose, rhamnose and arabinose monosaccharide in a molar ratio of 5:1:3, respectively. Morphological analysis revealed that EPSR4 possess a high crystallinity degree with a significant degree of porosity, and its aggregation and conformation in the lipid phase might have a significant impact on the bioactivity of EPSR4. The biological activity of EPSR4 was screened and evaluated by investigating its antioxidant, cytotoxicity, anti-inflammatory, and anti-Alzheimer activities. The antioxidant activity results showed that EPSR4 has 97.6% scavenging activity toward DPPH free radicals at 1500 µg/mL, with an IC50 value of 300 µg/mL, and 64.8% at 1500 µg/mL toward hydrogen peroxide free radicals (IC50 = 1500 µg/mL, 30 min). Furthermore, EPSR4 exhibited considerable inhibitory activity towards the proliferation of T-24 (bladder carcinoma), A-549 (lung cancer) and HepG-2 (hepatocellular carcinoma) cancer cell lines with IC50 of 244 µg/mL, 148 µg/mL and 123 µg/mL, respectively. An evaluation of anti-inflammatory activity revealed that EPSR4 has potent lipoxygenase (LOX) inhibitory activity (IC50 of 54.3 µg/mL) and a considerable effect on membrane stabilization (IC50 = 112.2 ± 1.2 µg/mL), while it showed cyclooxygenase (COX2) inhibitory activity up to 125 µg/mL. Finally, EPSR4 showed considerable inhibitory activity towards acetylcholine esterase activity. Taken together, this study reveals that Bacillus subtilis strain AG4 could be considered as a potential natural source of novel EPS with potent biological activities that would be useful for the healthcare system.

Novel Applications of NSAIDs: Insight and Future Perspectives in Cardiovascular, Neurodegenerative, Diabetes and Cancer Disease Therapy

Once it became clear that inflammation takes place in the modulation of different degenerative disease including neurodegenerative, cardiovascular, diabetes and cancer the researchers has started intensive programs evaluating potential role of non-steroidal anti-inflammatory drugs (NSAIDs) in the prevention or therapy of these diseases. This review discusses the novel mechanism of action of NSAIDs and its potential use in the pharmacotherapy of neurodegenerative, cardiovascular, diabetes and cancer diseases. Many different molecular and cellular factors which are not yet fully understood play an important role in the pathogenesis of inflammation, axonal damage, demyelination, atherosclerosis, carcinogenesis thus further NSAID studies for a new potential indications based on precise pharmacotherapy model are warranted since NSAIDs are a heterogeneous group of medicines with relative different pharmacokinetics and pharmacodynamics profiles. Hopefully the new data from studies will fill in the gap between experimental and clinical results and translate our knowledge into successful disease therapy.

Ibuprofen-based advanced therapeutics: breaking the inflammatory link in cancer, neurodegeneration, and diseases

Ibuprofen is a classical nonsteroidal anti-inflammatory drug (NSAID) highly prescribed to reduce acute pain and inflammation under an array of conditions, including rheumatoid arthritis, osteoarthritis, dysmenorrhea, and gout. Ibuprofen acts as a potential inhibitor for cyclooxygenase enzymes (COX-1 and COX-2). In the past few decades, research on this small molecule has led to identifying other possible therapeutic benefits. Anti-tumorigenic and neuroprotective functions of Ibuprofen are majorly recognized in recent literature and need further consideration. Additionally, several other roles of this anti-inflammatory molecule have been discovered and subjected to experimental assessment in various diseases. However, the major challenge faced by Ibuprofen and other drugs of similar classes is their side effects, and tendency to cause gastrointestinal injury, generate cardiovascular risks, modulate hepatic and acute kidney diseases. Future research should also be conducted to deduce new methods and approaches of suppressing the unwanted toxic changes mediated by these drugs and develop new therapeutic avenues so that these small molecules continue to serve the purposes. This article primarily aims to develop a comprehensive and better understanding of Ibuprofen, its pharmacological features, therapeutic benefits, and possible but less understood medicinal properties apart from major challenges in its future application.KEY POINTSIbuprofen, an NSAID, is a classical anti-inflammatory therapeutic agent.Pro-apoptotic roles of NSAIDs have been explored in detail in the past, holding the key in anti-cancer therapies.Excessive and continuous use of NSAIDs may have several side effects and multiple organ damage.Hyperactivated Inflammation initiates multifold detrimental changes in multiple pathological conditions.Targeting inflammatory pathways hold the key to several therapeutic strategies against many diseases, including cancer, microbial infections, multiple sclerosis, and many other brain diseases.

Nanotechnology for Medical and Surgical Glaucoma Therapy-A Review

Glaucoma is the second leading cause of blindness worldwide. Even though significant advances have been made in its management, currently available antiglaucoma therapies suffer from considerable drawbacks. Typically, the success and efficacy of glaucoma medications are undermined by their limited bioavailability to target tissues and the inadequate adherence demonstrated by patients with glaucoma. The latter is due to a gradual decrease in tolerability of lifelong topical therapies and the significant burden to patients of prescribed stepwise antiglaucoma regimens with frequent dosing which impact quality of life. On the other hand, glaucoma surgery is restricted by the inability of antifibrotic agents to efficiently control the wound healing process without causing severe collateral damage and long-term complications. Evolution of the treatment paradigm for patients with glaucoma will ideally include prevention of retinal ganglion cell degeneration by the successful delivery of neurotrophic factors, anti-inflammatory drugs, and gene therapies. Nanotechnology-based treatments may surpass the limitations of currently available glaucoma therapies through optimized targeted drug delivery, increased bioavailability, and controlled release. This review addresses the recent advances in glaucoma treatment strategies employing nanotechnology, including medical and surgical management, neuroregeneration, and neuroprotection.

Cellular and Molecular Mediators of Neuroinflammation in Alzheimer Disease

Alzheimer disease (AD) is a neurodegenerative disorder characterized by the loss of neuronal cells and the progressive decline of cognitive function. The major pathological culprit of AD is aggregation of amyloid-β (Aβ) and hyperphosphorylation of tau, eventually leading to progressive neuronal cell death and brain atrophy. However, the detailed molecular and cellular mechanisms underlying AD development as a result of neuronal cell death are little known. Although several hypotheses have been proposed regarding the development of AD, increasingly many studies suggest that the pathological progress of AD is not restricted to neuronal components such as Aβ and tau, but is also closely related to inflammatory responses in the brain. Abnormalities of Aβ and tau cause activity of pattern recognition receptors on the brain’s immune cells, including microglia and astrocytes, and trigger the innate immune system by releasing inflammatory mediators in the pathogenesis of AD. In this review, we present a basic overview of the current knowledge regarding inflammation and molecular mediators in the pathological progress of AD.

Features and outcomes of drugs for combination therapy as multi-targets strategy to combat Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD), a deleterious neurodegenerative disorder that impairs memory, cognitive functions and may lead to dementia in late stage of life. The pathogenic cause of AD remains incompletely understood and FDA approved drugs are partial inhibitors rather than curative. Most of drugs are synthetic or natural products as galanthamine is an alkaloid obtained from Galanthus spp. Huperzine A, an alkaloid found in Huperzia spp., gingkolides a diterpenoids from Gingko biloba and many ethnobotanicals like Withania somnifera (L.) Dunal., Physostigma venenosum Balf., Bacopa monnieri (L.) Wettst., Centella asiatica (L.) Urb. have been used by traditional Indian, Chinese, and European system of medicines in AD. Clinical significance opioid alkaloid in Papaver somniferum has shown another dimension to this study. Over exploitation of medicinal plants with limited bioactive principles has provided templates to design synthetic drugs in AD e.g. rivastigmine, phenserine, eptastigmine based on chemical structure of physostigmine of Physostigma venenosum Balf. Even ZT-1 a prodrug of Hup A and memogain a prodrug of galantamine has achieved new direction in drug development in AD. All these first-line cholinesterase-inhibitors are used as symptomatic treatments in AD. Single modality of "One-molecule-one-target" strategy for treating AD has failed and so future therapies on "Combination-drugs-multi-targets" strategy (CDMT) will need to address multiple aspects to block the progression of pathogenesis of AD. Besides, cholinergic and amyloid drugs, in this article we summarize proteinopathy-based drugs as AD therapeutics from a variety of biological sources. In this review, an attempt has been made to elucidate the molecular mode of action of various plant products, and synthetic drugs investigated in various preclinical and clinical tests in AD. It also discusses current attempts to formulate a comprehensive CDMT strategy to counter complex pathogenesis in AD.

MATERIALS AND METHODS

Information were collected from classical books on medicinal plants, pharmacopoeias and scientific databases like PubMed, Scopus, GoogleScholar, Web of Science and electronic searches were performed using Cochrane Library, Medline and EMBASE. Also published scientific literatures from Elsevier, Taylor and Francis, Springer, ACS, Wiley publishers and reports by government bodies and documentations were assessed.

RESULTS

60 no. of natural and synthetic drugs have been studied with their significant bioactivities. A decision matrix designed for evaluation of drugs for considering to the hypothetic "CDMT" strategy in AD. We have introduced the scoring pattern of individual drugs and based on scoring pattern, drugs that fall within the scoring range of 18-25 are considered in the proposed CDMT. It also highlights the importance of available natural products and in future those drugs may be considered in CDMT along with the qualified synthetic drugs.

CONCLUSION

A successful validation of the CDMT strategy may open up a debate on health care reform to explore other possibilities of combination therapy. In doing so, it should focus on clinical and molecular relationships between AD and CDMT. A better understanding of these relationships could inform and impact future development of AD-directed treatment strategies. This strategy also involves in reducing costs in treatment phases which will be affordable to a common man suffering from AD.

New carboxamide derivatives bearing benzenesulphonamide as a selective COX-II inhibitor: Design, synthesis and structure-activity relationship

Sixteen new carboxamide derivatives bearing substituted benzenesulphonamide moiety (7a-p) were synthesized by boric acid mediated amidation of appropriate benzenesulphonamide with 2-amino-4-picoline and tested for anti-inflammatory activity. One compound 7c showed more potent anti-inflammatory activity than celecoxib at 3 h in carrageenan-induced rat paw edema bioassay. Compounds 7g and 7k also showed good anti-inflammatory activity comparable to celecoxib. Compound 7c appeared selectivity index (COX-2/COX-1) better than celecoxib. Compound 7k appeared selectivity index (COX-2/COX-1) a little higher than the half of celecoxib while compound 7g is non-selective for COX-2. The LD₅₀ of compounds 7c, 7g and 7k were comparable to celecoxib.

Arsenic affects inflammatory cytokine expression in Gallus gallus brain tissues

Background

The heavy metal arsenic is widely distributed in nature and posses a serious threat to organism’s health. However, little is known about the arsenic-induced inflammatory response in the brain tissues of birds and the relationship and mechanism of the inflammatory response. The purpose of this study was to explore the effects of dietary arsenic on the expression of inflammatory cytokines in the brains of Gallus gallus.

Results

Seventy-two 1-day-old male Hy-line chickens were divided into a control group, a low arsenic trioxide (As₂O₃)-treated (7.5 mg/kg) group, a middle As₂O₃-treated (15 mg/kg) group, and a high As₂O₃-treated (30 mg/kg) group. Arsenic exposure caused obvious ultrastructural changes. The mRNA levels of the transcription factor nuclear factor-κB (NF-κB) and of pro-inflammatory cytokines, including inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and prostaglandin E synthase (PTGEs), in chicken brain tissues (cerebrum, cerebellum, thalamus, brainstem and myelencephalon) on days 30, 60 and 90, respectively, were measured by real-time PCR. The protein expression of iNOS was detected by western blot. The results showed that after being treated with As₂O_3, the levels of inflammatory-related factor NF-κB and pro-inflammatory cytokines in chicken brain tissues increased (P < 0.05).

Conclusions

Arsenic exposure in the chickens triggered host defence and induced an inflammatory response by regulating the expression of inflammatory-related genes in the cerebrum, cerebellum, thalamus, brainstem and myelencephalon. These data form a foundation for further research on arsenic-induced neurotoxicity in Gallus gallus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1066-8) contains supplementary material, which is available to authorized users.

Neuronal Gene Targets of NF-κB and Their Dysregulation in Alzheimer's Disease

Although, better known for its role in inflammation, the transcription factor nuclear factor kappa B (NF-κB) has more recently been implicated in synaptic plasticity, learning, and memory. This has been, in part, to the discovery of its localization not just in glia, cells that are integral to mediating the inflammatory process in the brain, but also neurons. Several effectors of neuronal NF-κB have been identified, including calcium, inflammatory cytokines (i.e., tumor necrosis factor alpha), and the induction of experimental paradigms thought to reflect learning and memory at the cellular level (i.e., long-term potentiation). NF-κB is also activated after learning and memory formation in vivo. In turn, activation of NF-κB can elicit either suppression or activation of other genes. Studies are only beginning to elucidate the multitude of neuronal gene targets of NF-κB in the normal brain, but research to date has confirmed targets involved in a wide array of cellular processes, including cell signaling and growth, neurotransmission, redox signaling, and gene regulation. Further, several lines of research confirm dysregulation of NF-κB in Alzheimer's disease (AD), a disorder characterized clinically by a profound deficit in the ability to form new memories. AD-related neuropathology includes the characteristic amyloid beta plaque formation and neurofibrillary tangles. Although, such neuropathological findings have been hypothesized to contribute to memory deficits in AD, research has identified perturbations at the cellular and synaptic level that occur even prior to more gross pathologies, including transcriptional dysregulation. Indeed, synaptic disturbances appear to be a significant correlate of cognitive deficits in AD. Given the more recently identified role for NF-κB in memory and synaptic transmission in the normal brain, the expansive network of gene targets of NF-κB, and its dysregulation in AD, a thorough understanding of NF-κB-related signaling in AD is warranted and may have important implications for uncovering treatments for the disease. This review aims to provide a comprehensive view of our current understanding of the gene targets of this transcription factor in neurons in the intact brain and provide an overview of studies investigating NF-κB signaling, including its downstream targets, in the AD brain as a means of uncovering the basic physiological mechanisms by which memory becomes fragile in the disease.

Glucocorticoids: Protectors of the Brain during Innate Immune Responses

The innate immune response is a coordinated set of reactions involving cells of myeloid lineage and a network of signaling molecules. Such a response takes place in the CNS during trauma, stroke, spinal cord injury, and neurodegenerative diseases, suggesting that macrophages/microglia are the cells that perpetuate the progressive neuronal damage. However, there is accumulating evidence that these cells and their secreted proinflammatory molecules have more beneficial effects than detrimental consequences for the neuronal elements. Indeed, a timely controlled innate immune response may limit toxicity in swiftly eliminating foreign materials and debris that are known to interfere with recovery and regeneration. Each step of the immune cascade is under the tight control of stimulatory and inhibitory signals. Glucocorticoids (GCs) act as the critical negative feedback on all myeloid cells, including those present within the brain parenchyma. Because too little is like too much, both an inappropriate feedback of GCs on microglia and high circulating GC levels in stressed individuals have been associated with deleterious consequences for the brain. In this review, the authors discuss both sides of the story with a particular emphasis on the neuro-protective role of endogenous GCs during immune challenges and the problems in determining whether GCs can be a good therapy for the treatment of neuropathological conditions.

Discovery of a potent cyclooxygenase-2 inhibitor, S4, through docking-based pharmacophore screening, in vivo and in vitro estimations

Cyclooxygenase (COX; EC: 1.14.99.1), the key enzyme in prostaglandin production in the human body, is a major pharmacological target for developing anti-inflammatory agents.

Splicing Regulation of Pro-Inflammatory Cytokines and Chemokines: At the Interface of the Neuroendocrine and Immune Systems

Alternative splicing plays a key role in posttranscriptional regulation of gene expression, allowing a single gene to encode multiple protein isoforms. As such, alternative splicing amplifies the coding capacity of the genome enormously, generates protein diversity, and alters protein function. More than 90% of human genes undergo alternative splicing, and alternative splicing is especially prevalent in the nervous and immune systems, tissues where cells need to react swiftly and adapt to changes in the environment through carefully regulated mechanisms of cell differentiation, migration, targeting, and activation. Given its prevalence and complexity, this highly regulated mode of gene expression is prone to be affected by disease. In the following review, we look at how alternative splicing of signaling molecules—cytokines and their receptors—changes in different pathological conditions, from chronic inflammation to neurologic disorders, providing means of functional interaction between the immune and neuroendocrine systems. Switches in alternative splicing patterns can be very dynamic and can produce signaling molecules with distinct or antagonistic functions and localization to different subcellular compartments. This newly discovered link expands our understanding of the biology of immune and neuroendocrine cells, and has the potential to open new windows of opportunity for treatment of neurodegenerative disorders.

Rutin upregulates neurotrophic factors resulting in attenuation of ethanol-induced oxidative stress in HT22 hippocampal neuronal cells

BACKGROUND

Alcoholism, which refers to the excessive consumption of alcohol, has deleterious effects on personal and social health worldwide. Oxidative stress evoked by ethanol plays an important role in the pathogenesis of neurodegenerative diseases. Rutin is a bioflavonoid that has been demonstrated to scavenge superoxide radicals. However, the effects of rutin on neuronal toxicity following ethanol-induced oxidative stress have not previously been investigated. Thus we investigated the antioxidant effect of rutin in hippocampal neuronal cells (HT22 cells) exposed to ethanol.

RESULTS

We found that rutin pretreatment prevented the ethanol-induced decrease in protein level expression of nerve growth factor, glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in HT22 cells. Cell viability as analyzed by the MTT method revealed a significant increase in cell viability in the rutin-treated group compared with the ethanol-only treated group. Antioxidant effect of rutin was confirmed to be due to reduction of intracellular reactive oxidative species production in ethanol-treated HT22 cells. Moreover, rutin significantly increased the level of the antioxidant glutathione, and the activities of the antioxidant enzymes superoxide dismutase and catalase.

CONCLUSION

These findings indicate that rutin has potential as a therapeutic agent to treat alcohol-related neurodegenerative disorders.

Green Tea Lowers Hepatic COX-2 and Prostaglandin E2 in Rats with Dietary Fat-Induced Nonalcoholic Steatohepatitis

Green tea extract (GTE) protects against nonalcoholic steatohepatitis (NASH) by decreasing hepatic steatosis and nuclear factor kappa B (NFκB) activation. We hypothesized that hypolipidemic and anti-inflammatory activities of GTE would protect against NASH by reducing cyclooxygenase-2 (COX-2), an NFκB-dependent enzyme, and prostaglandin E2 (PGE2) in a dietary fat-induced obese model. Male Wistar rats were fed a low-fat diet containing no GTE or a high-fat (HF) diet containing GTE at 0%, 1%, or 2% for 8 weeks. Insulin resistance and total hepatic fatty acids increased following HF feeding (P<.05) and these were normalized by GTE at 1-2%. GTE (1-2%) normalized hepatic malondialdehyde without affecting cytochrome P450 2E1 mRNA expression, which was otherwise increased by HF feeding. HF-mediated increases in hepatic COX-2 protein and activity as well as PGE2 concentrations were normalized by GTE (1-2%). COX-2 activity and PGE2 were correlated to each other, and to serum alanine aminotransferase (ALT) and hepatic NFκB-binding activity (P<.05; r=0.28-0.49). GTE attenuated HF-mediated increases in total hepatic n-6 and n-3, without affecting the n-6/n-3 ratio. GTE did not affect HF-mediated increases in n-6 in nonesterified fatty acid (NEFA) and phospholipid pools, whereas n-3 and n-6/n-3 in both pools were unaffected by GTE and HF feeding. GTE decreased total hepatic arachidonic acid without affecting HF-mediated increases in arachidonic acid in NEFA or phospholipid pools. Thus, GTE attenuates lipid peroxidation and PGE2 accumulation by decreasing COX-2 activity independent of arachidonic acid availability and supports an additional mechanism by which GTE protects against liver injury during NASH in an HF-feeding model.

Anticancer, anti-inflammatory, and analgesic activities of synthesized 2-(substituted phenoxy) acetamide derivatives

The aphorism was to develop new chemical entities as potential anticancer, anti-inflammatory, and analgesic agents. The Leuckart synthetic pathway was utilized in development of novel series of 2-(substituted phenoxy)-N-(1-phenylethyl)acetamide derivatives. The compounds containing 1-phenylethylamine as basic moiety attached to substituted phenols were assessed for their anticancer activity against MCF-7 (breast cancer), SK-N-SH (neuroblastoma), anti-inflammatory activity, and analgesic activity. These investigations revealed that synthesized products 3a-j with halogens on the aromatic ring favors as the anticancer and anti-inflammatory activity. Among all, compound 3c N-(1-(4-chlorophenyl)ethyl)-2-(4-nitrophenoxy)acetamide exhibited anticancer, anti-inflammatory, and analgesic activities. In conclusion, 3c may have potential to be developed into a therapeutic agent.

Therapeutic approaches to age-associated neurocognitive disorders

The United Nations projects that the number of individuals with dementia in developed countries alone will be approximately 36,7 million by the year 2050. International recognition of the significant emotional and economic burden of Alzheimer's disease has been matched by a dramatic increase in the development of pharmacological and nonpharmacological approaches to this illness in the past decade. Changing demographics have underscored the necessity to develop similar approaches for the remediation of the cognitive impairment associated with more benign syndromes, such as mild cognitive impairment (MCI) and age-associated cognitive decline (AACD). The present article aims to provide an overview of the most current therapeutic approaches to age-associated neurocognitive disorders. Additionally, it discusses the conceptual and methodological issues that surround the design, implementation, and interpretation of such approaches.

Insights into the effects of diclofenac and other non-steroidal anti-inflammatory agents on ion channels

OBJECTIVES

Diclofenac and other non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in the treatment of inflammation and pain. Most effects of NSAIDs are attributed to the inhibition of cyclooxygenases (COX). However, many NSAIDs may have other effects not related to COX, including the modulation of various ion channels. The clinical implications of the effects on channels are not fully understood. This review outlines the effects of NSAIDs, with special attention to diclofenac, on ion channels and highlights the possible underlying mechanisms.

KEY FINDINGS

NSAIDs have effects on channels such as inhibition, activation or changes in expression patterns. The channels affected include voltage-gated Na(+) , Ca(2+) , or K(+) channels, ligand-gated K(+) channels, transient receptor potential and other cation channels as well as chloride channels in several types of cells. The mechanisms of drug actions not related to COX inhibition may involve drug-channel interactions, interference with the generation of second messengers, changes in channel expression, or synergistic/antagonist interactions with other channel modulators.

SUMMARY

The effects on ion channels may account for novel therapeutic actions of NSAIDs or for adverse effects. Among the NSAIDs, diclofenac may serve as a template for developing new channel modulators and as a tool for investigating the actions of other drugs.

Hydrophilic prodrug approach for reduced pigment binding and enhanced transscleral retinal delivery of celecoxib

Transscleral retinal delivery of celecoxib, an anti-inflammatory and anti-VEGF agent, is restricted by its poor solubility and binding to the melanin pigment in choroid-RPE. The purpose of this study was to develop soluble prodrugs of celecoxib with reduced pigment binding and enhanced retinal delivery. Three hydrophilic amide prodrugs of celecoxib, celecoxib succinamidic acid (CSA), celecoxib maleamidic acid (CMA), and celecoxib acetamide (CAA) were synthesized and characterized for solubility and lipophilicity. In vitro melanin binding to natural melanin (Sepia officinalis) was estimated for all three prodrugs. In vitro transport studies across isolated bovine sclera and sclera-choroid-RPE (SCRPE) were performed. Prodrug with the highest permeability across SCRPE was characterized for metabolism and cytotoxicity and its in vivo transscleral delivery in pigmented rats. Aqueous solubilities of CSA, CMA, and CAA were 300-, 182-, and 76-fold higher, respectively, than celecoxib. Melanin binding affinity and capacity were significantly lower than for celecoxib for all three prodrugs. Rank order for the % in vitro transport across bovine sclera and SCRPE was CSA > CMA ~ CAA ~ celecoxib, with the transport being 8-fold higher for CSA than celecoxib. CSA was further assessed for its metabolic stability and in vivo delivery. CSA showed optimum metabolic stability in all eye tissues with only 10-20% conversion to parent celecoxib in 30 min. Metabolic enzymes responsible for bioconversion included amidases, esterase, and cytochrome P-450. In vivo delivery in pigmented BN rats showed that CSA had 4.7-, 1.4-, 3.3-, 6.0-, and 4.5-fold higher delivery to sclera, choroid-RPE, retina, vitreous, and lens than celecoxib. CSA has no cytotoxicity in ARPE-19 cells in the concentration range of 0.1 to 1000 μM. Celecoxib succinamidic acid, a soluble prodrug of celecoxib with reduced melanin binding, enhances transscleral retinal delivery of celecoxib.

Cyclo-oxygenase-2 knockout genotype in mice is associated with blunted angiotensin II-induced oxidative stress and hypertension

BACKGROUND

Inflammation and oxidative stress have been identified as integral parts in the pathogenesis of hypertension. Cyclo-oxygenase-2 which could elicit inflammation and free radicals generation appears to be a key enzyme in hypertension. Cyclo-oxygenase-2 expression and oxidative stress in cardiovascular tissues are increased in the angiotensin II model.

METHODS

Cyclo-oxygenase-1 and cyclo-oxygenase-2 deficient mice and their cultured aortic smooth muscle cells were used to investigate the role of these enzymes in angiotensin II induced superoxide production and hypertension.

RESULTS

At resting state, the superoxide production in aortic and cardiac tissues was lower in cyclo-oxygenase-2 deficient than in the wild type or in cyclo-oxygenase-1 deficient mice. Chronic angiotensin II infusion increased the superoxide production in these tissues from both cyclo-oxygenase-deficient and wild-type mice whereas the level in cyclo-oxygenase-2 deficient mice was equivalent to the basal level in wild-type mice. The hypertensive effect of angiotensin II was attenuated in cyclo-oxygenase-2 deficient mice. Aspirin treatment reduced the basal superoxide production and blunted the oxidative and hypertensive effect of angiotensin II in wild type and cyclo-oxygenase-1 deficient mice whereas it lost completely its antioxidative property in angiotensin II-treated aortic smooth muscle cells isolated from cyclo-oxygenase-2 deficient mice.

CONCLUSIONS

Cyclo-oxygenase-2 pathway plays a major role in the superoxide generation as well as in the angiotensin II-induced oxidative stress and blood pressure. Cyclo-oxygenase-1 activity didn't show any influence on these parameters. These results suggest that cyclo-oxygenase-2 is involved in the pathogenesis of hypertension.

Microwave assisted synthesis of novel pyrazolone derivatives attached to a pyrimidine moiety and evaluation of their anti-inflammatory, analgesic and antipyretic activities

In the present research work, the motto was to develop new chemical entities as potential anti-inflammatory, analgesic and antipyretic agents. Various 4-(2-amino-6-(substituted)pyrimidin-4-yl)-3-methyl-1-(substituted)-1H-pyrazol-5(4H)-one derivatives (5a-5j) and their Schiff bases (6a-6j) were synthesized. The newly synthesized compounds were characterized by TLC and spectral data. The compounds containing pyrazolone and amino pyrimidine as basic moieties (5a-5j), were screened for their anti-inflammatory, analgesic and antipyretic activities, compounds 5a, 5c-5f, 5h exhibited activities nearly similar to the standard. The pharmacological studies reveal that the presence of 4-hydroxy, 4-methoxy, 4-(N,N-dimethylamino) or 2-hydroxy groups on phenyl ring at C6 of amino pyrimidine exhibits anti-inflammatory, analgesic and antipyretic activities nearly similar to the standard and substitutions like 4-chloro, 2-nitro, 3-nitro or 4-nitro on same phenyl ring lead to a decrease in activities.

Human prostaglandin H synthase (hPHS)-1- and hPHS-2-dependent bioactivation, oxidative macromolecular damage, and cytotoxicity of dopamine, its precursor, and its metabolites

The dopamine (DA) precursor l-dihydroxyphenylalanine (L-DOPA) and metabolites dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 3-methoxytyramine may serve as substrates for prostaglandin H synthase (PHS)-catalyzed bioactivation to free radical intermediates. We used CHO-K1 cells expressing human (h) PHS-1 or hPHS-2 to investigate hPHS isozyme-dependent oxidative damage and cytotoxicity. hPHS-1- and hPHS-2-expressing cells incubated with DA, L-DOPA, DOPAC, or HVA exhibited increased cytotoxicity compared to untransfected cells, and cytotoxicity was increased further by exogenous arachidonic acid (AA), which increased hPHS activity. Preincubation with catalase, which detoxifies reactive oxygen species, or acetylsalicylic acid, an inhibitor of hPHS-1 and -2, reduced the cytotoxicity caused by DA, L-DOPA, DOPAC, and HVA in hPHS-1 and -2 cells both with and without AA. Protein oxidation was increased in hPHS-1 and -2 cells exposed to DA or L-DOPA and further increased by AA addition. DNA oxidation was enhanced earlier and at lower substrate concentrations than protein oxidation in both hPHS-1 and -2 cells by DA, L-DOPA, DOPAC, and HVA and further enhanced by AA addition. hPHS-2 cells seemed more susceptible than hPHS-1 cells, whereas untransfected CHO-K1 cells were less susceptible. Thus, isozyme-specific, hPHS-dependent oxidative damage and cytotoxicity caused by neurotransmitters, their precursors, and their metabolites may contribute to neurodegeneration associated with aging.

Human prostaglandin H synthase (hPHS)-1 and hPHS-2 in amphetamine analog bioactivation, DNA oxidation, and cytotoxicity

Neurotoxicity of the amphetamine analogs methamphetamine (METH) and 3,4-methylenedioxyamphetamine (MDA) (the active metabolite of ecstasy) may involve their prostaglandin H synthase (PHS)-dependent bioactivation to free radical intermediates that generate reactive oxygen species and oxidatively damage cellular macromolecules. We used Chinese hamster ovary-K1 (CHO-K1) cell lines either untransfected or stably expressing human PHS-1 (hPHS-1) or hPHS-2 to investigate hPHS isozyme-dependent oxidative damage and cytotoxicity. Both METH and MDA (250-1000 μM) caused concentration-independent cytotoxicity in hPHS-1 cells, suggesting maximal bioactivation at the lowest concentration. In hPHS-2 cells, with half the activity of hPHS-1 cells, METH (250-1000 μM) cytotoxicity was less than that for hPHS-1 cells but was concentration dependent and increased by exogenous arachidonic acid (AA), which increased hPHS activity. Whereas 10 μM MDA and METH were not cytotoxic, at 100 μM both analogs caused AA-dependent and concentration-dependent increases in cytotoxicity and DNA oxidation in both hPHS-1/2 cells. The hPHS-2 isozyme appeared to provide more efficacious bioactivation of these amphetamine analogs. Acetylsalicylic acid, an irreversible inhibitor of both hPHS-1 and hPHS-2, blocked cytotoxicity and DNA oxidation in both cell lines and untransfected CHO-K1 cells lacking PHS activity were similarly resistant. Accordingly, isozyme-dependent hPHS-catalyzed bioactivation of METH and MDA can cause oxidative macromolecular damage and cytotoxicity, which may contribute to their neurotoxicity.

Recent methodologies toward the synthesis of valdecoxib: a potential 3,4-diarylisoxazolyl COX-II inhibitor

Non-steroidal anti-inflammatory drugs are widely used therapeutic agents in the treatment of inflammation, pain and fever. Cyclooxygenase catalyzes the initial step of biotransformation of arachidonic acid to prostanoids, and exist as three distinct isozymes; COX-I, COX-II and COX-III. Selective COX-II inhibitors are a class of potential anti-inflammatory, analgesic, and antipyretic drugs with reduced gastrointestinal (GI) side effects compared to nonselective inhibitors. 3,4-Diarylisoxazole scaffold is recurrently found in a wide variety of NSAIDs, protein kinase inhibitors, hypertensive agents, and estrogen receptor (ER) modulators. In the present review, we document on the recent synthetic strategies of 3,4-diarylisoxazolyl scaffolds of valdecoxib and its relevant structural analogues.

Neuroinflammation, microglia and implications for anti-inflammatory treatment in Alzheimer's disease

Neuroinflammation has been implicated in the pathology of Alzheimer's disease (AD) for decades. Still it has not been fully understood when and how inflammation arises in the course of AD. Whether inflammation is an underling cause or a resulting condition in AD remains unresolved. Mounting evidence indicates that microglial activation contributes to neuronal damage in neurodegenerative diseases. However, also beneficial aspects of microglial activation have been identified. The purpose of this review is to highlight new insights into the detrimental and beneficial role of neuroinflammation in AD. It is our intention to focus on newer controversies in the field of microglia activation. Precisely, we want to shed light on whether neuroinflammation is associated to brain tissue damage and functional impairment or is there also a damage limiting activity. In regard to this, we discuss the limitations and the advantages of anti-inflammatory treatment options and identify what future implications might result from this underling neuroinflammation for AD therapy.

Species-difference of cyclooxygenase-2 in the hippocampus of rodents

Cyclooxygenase (COX) generates free radicals and it is important in inflammatory response. In this study, we observed the immunoreactivity in mice (ICR and C57BL/6 strain), rats and gerbils. In these animals, COX-2 immunoreactivity was mainly detected in pyramidal cells of the hippocampal CA2/3 region and in granule cells of the dentate gyrus. COX-2 immunoreactivity in the CA2/3 region was the highest in ICR mice, while in gerbils COX-2 immunoreactivity was the lowest; COX-2 immunoreactivity in the dentate gyrus was the highest in rats and the lowest in gerbils. The protein levels of COX-2 were similar to the immunohistochemical data. COX-2 mRNA transcript was the highest in the gerbil and the lowest in the rat. In brief, COX-2 protein, not mRNA, in the hippocampus is generally higher in mice (ICR and C57BL/6 strain) than rats and gerbils.

Characterization of scavengers of gamma-ketoaldehydes that do not inhibit prostaglandin biosynthesis

Expression of cyclooxygenase-2 (COX-2) is associated with the development of many pathologic conditions. The product of COX-2, prostaglandin H(2) (PGH(2)), can spontaneously rearrange to form reactive gamma-ketoaldehydes called levuglandins (LGs). This gamma-ketoaldehyde structure confers a high degree of reactivity on the LGs, which rapidly form covalent adducts with primary amines of protein residues. Formation of LG adducts of proteins has been demonstrated in pathologic conditions (e.g., increased levels in the hippocampus in Alzheimer's disease) and during physiologic function (platelet activation). On the basis of knowledge that lipid modification of proteins is known to cause their translocation and to alter their function, we hypothesize that modification of proteins by LG could have functional consequences. Testing this hypothesis requires an experimental approach that discriminates between the effects of protein modification by LG and the effects of cyclooxygenase-derived prostanoids acting through their G-protein coupled receptors. To achieve this goal, we have synthesized and evaluated a series of scavengers that react with LG with a potency more than 2 orders of magnitude greater than that with the epsilon-amine of lysine. A subset of these scavengers are shown to block the formation of LG adducts of proteins in cells without inhibiting the catalytic activity of the cyclooxygenases. Ten of these selective scavengers did not produce cytotoxicity. These results demonstrate that small molecules can scavenge LGs in cells without interfering with the formation of prostaglandins. They also provide a working hypothesis for the development of pharmacologic agents that could be used in experimental animals in vivo to assess the pathophysiological contribution of levuglandins in diseases associated with cyclooxygenase up-regulation.

Systemic administration of lipopolysaccharide induces cyclooxygenase-2 immunoreactivity in endothelium and increases microglia in the mouse hippocampus

In this study, we observed the effects of lipopolysaccharide (LPS) on neurodegeneration and immune response in the hippocampus. LPS is a gram-negative bacterial cell surface proteoglycan and known as a bacterial endotoxin. For this, we investigated the optimal concentration of LPS influencing the ICR mouse hippocampus to measure the LPS receptor, e.g., toll-like receptor 4 (TLR4), expression in mouse hippocampal homogenates. TLR4 expression was significantly and prominently increased in the hippocampal homogenates of the LPS (1 mg/kg)-treated group. Next, we examined pro-inflammatory response in the hippocampus using cyclooxygenase-2 (COX-2, a marker for inflammatory response) immunohistochemistry after LPS treatment. COX-2 immunoreactivity was significantly increased in the endothelium of blood vessels in the hippocampus 6 h after LPS treatment, judging from double immunofluorescence study with platelet-derived endothelial cell adhesion molecule-1 (PECAM-1, a marker for endothelial cells): it decreased 12 h and disappeared 24 h after LPS treatment. In addition, the ionized calcium-binding adapter molecule 1 (Iba-1)-immunoreactive ((+)) microglia were morphologically activated in the mouse hippocampus after LPS treatment. At 24 h after LPS treatment, Iba-1(+) microglia of activated forms were abundant in the hippocampus. However, NeuN (a neuron-specific soluble nuclear antigen)(+) neurons were not significantly changed in the hippocampus after LPS treatment. Fluoro-jade B (a marker for neuronal degeneration)(+) cells were not detected in the hippocampus at any time after LPS treatment. In addition, there were no significant differences in permeability of blood-brain barriers at any time points after LPS treatment. In brief, our results indicate that intraperitoneal administration of 1 mg/kg LPS effectively induces LPS receptor (TLR4) expression in the hippocampus, and the treatment increases corticosterone levels, inflammation in the blood vessels, and microglial activation in the hippocampus without any neuronal damage.

Cyclooxygenase-2 immunoreactivity and protein level in the gerbil hippocampus during normal aging

Cyclooxygenases-2 (COX-2) is not only related to inflammation but also plays critical roles in brain development and synaptic signaling. In the present study, we investigated age-related changes in COX-2 immunoreactivity and protein levels in the gerbil hippocampus. In the hippocampal CA1 region (CA1) and dentate gyrus (DG), weak COX-2 immunoreactivity was observed at postnatal month 1 (PM 1), and COX-2 immunoreactivity was markedly increased at PM 18 and 24. In the CA2/3, COX-2 immunoreactivity was strong at PM 1. COX-2 immunoreactivities in the PM 3, 6 and 12 groups were decreased compared to that in the PM 1 group, and it was increased at PM 18 and 24. In addition, age-related changes in COX-2 levels were similar with immunohistochemical results in the CA2/3. These results suggest that COX-2 immunoreactivity and levels were high in the hippocampus of aged gerbils.

Comparative pharmacological study of free radical scavenger, nitric oxide synthase inhibitor, nitric oxide synthase activator and cyclooxygenase inhibitor against MPTP neurotoxicity in mice

The biochemical and cellular changes that occur following the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are remarkably similar to that seen in idiopathic Parkinson's disease(PD). There is growing evidence indicating that reactive oxygen species (ROS), reactive nitrogen species (RNS) and inflammation are a major contributor to the pathogenesis and progression of PD. Hence, we investigated whether 7-nitroindazole [neuronal nitric oxide synthase (nNOS) inhibitor], edaravone (free radical scavenger), minocycline [inducible NOS (iNOS) inhibitor], fluvastatin [endothelial NOS (eNOS) activator], pitavastatin (eNOS activator), etodolac [cyclooxygenase-2 (COX-2) inhibitor] and indomethacin (COX inhibitor) can protect against MPTP neurotoxicity in mice under the same conditions. For the evaluation of each drug, the levels of dopamine, DOPAC and HVA were quantified using HPLC with an electrochemical detector. Four administrations of MPTP at 1-h intervals to mice produced marked depletion of dopamine, DOPAC (3,4-dihydroxyphenylacetic acid) and HVA (homovanilic acid) in the striatum after 5 days. 7-Nitroindazole prevented dose-dependently a significant reduction in dopamine contents of the striatum 5 days after MPTP treatment. In contrast, edaravone, minocycline, fluvastatin, pitavastatin, etodolac and indomethacin did not show the neuroprotective effect on MPTP-induced striatal dopamine, DOPAC and HVA depletions after 5 days. The present study demonstrates that the overexpression of nNOS may play a major role in the neurotoxic processes of MPTP, as compared with the production of ROS, the overexpression of iNOS, the modulation of eNOS and the involvement of inflammatory response. Thus our pharmacological findings provide further information for progressive neurodegeneration of the nigrostriatal dopaminergic neuronal pathway.

HIV-2 induces NF-kappaB activation and cyclooxygenase-2 expression in human astroglial cells

HIV-2 invades CNS and causes neurological disease as well as HIV-1 does. Induction of COX-2 in CNS of HIV-1 infected people has been proposed as a cause of cognitive impairment, so we tested whether HIV-2 may cause damage by a similar mechanism. COX-2 mRNA and protein expression were induced in human astrocytes upon interaction with HIV-2, being this induction abrogated by CXCR4 antagonists. HIV-2 induced COX-2 promoter transcription and deletion of the two NF-kappaB binding sites of the promoter abrogated this induction. Neither AP-1 nor NFAT seem to be involved in COX-2 transcriptional activation. Overexpression of IkappaBalpha completely abrogated COX-2 induction, and transfection of p65/relA NF-kappaB induced COX-2 transcription. Interestingly, HIV-2 activated NF-kappaB by inducing p65/relA transactivating activity through Ser536 phosphorylation. Moreover, the astrocyte activation induced by HIV-2 was abrogated by different COX inhibitors. In summary, HIV-2 induces COX-2 in human astrocytes depending on CXCR4 coreceptor.

Glial cell dysregulation: a new perspective on Alzheimer disease

Alzheimer disease (AD) is a major cause of dementia. Several mechanisms have been postulated to explain its pathogenesis, beta-amyloid (A beta toxicity, cholinergic dysfunction, Tau hyper-phosphorylation, oxidative damage, synaptic dysfunction and inflammation secondary to senile plaques, among others. Glial cells are the major producers of inflammatory mediators, and cytotoxic activation of glial cells is linked to several neurodegenerative diseases; however, whether inflammation is a consequence or the cause of neurodegeneration is still unclear. I propose that inflammation and cellular stress associated with aging are key events in the development of AD through the induction of glial dysfunction. Dysregulated inflammatory response can elicit glial cell activation by compounds which are normally poorly reactive. Inflammation can also be the major cause of defective handling of A beta and the amyloid precursor protein (APP). Here I review evidence that support the proposal that dysfunctional glia and the resulting neuroinflammation can explain many features of AD. Evidence supports the notion that damage caused by inflammation is not only a primary cause of neurodegeneration but also an inducer for the accumulation of A beta in AD. Dysfunctional glia can result in impaired neuronal function in AD, as well as in many progressive neurodegenerative disorders. We show that microglial cell activation is enhanced under pro-inflammatory conditions, indicating that glial cell responses to A beta related proteins can be critically dependent on the priming of glial cells by pro-inflammatory factors.

Expression and localization of prostaglandin transporter in Alzheimer disease brains and age-matched controls

Neuroinflammation, a major contributor to neurodegenerative diseases, involves the contribution of activated microglia, reactive astrocytes, and infiltrating inflammatory cells. Stress and various acute or chronic brain injuries stimulate the generation of free radicals and glutamate, triggering inflammatory pathways that lead to increases in chemokines, cytokines, and prostaglandins. Prostaglandins are lipid mediators of inflammation that are produced from arachidonic acid by cyclooxygenase enzymes. They are generally believed to be in all tissues and organs. Their transport through the lipid bilayers of the cell membranes/organelles is facilitated by the prostaglandin transporter (PGT). In this study, middle frontal gyrus brain tissue from patients diagnosed with Alzheimer disease (AD) and that of age-matched control brains were examined to determine the protein expression pattern of PGT and its possible role in modulating neuroinflammation associated with AD. Immunohistochemical and immunofluorescent studies showed that PGT protein was expressed in all the brain tissues examined and was localized in neurons, microglia, and astrocytes. Interestingly, Western blot analysis revealed that the PGT level was significantly less in AD than in age-matched control brain homogenates. Further work is warranted to address the possibility and implications that prostaglandins might not be cleared at a proper rate in AD brains.

Neuronal effects of 4-t-Butylcatechol: a model for catechol-containing antioxidants

Many herbal medicines and dietary supplements sold as aids to improve memory or treat neurodegenerative diseases or have other favorable effects on the CNS contain a catechol or similar 1,2-dihydroxy aromatic moiety in their structure. As an approach to isolate and examine the neuroprotective properties of catechols, a simple catechol 4-t-Butylcatechol (TBC) has been used as a model. In this study, we investigated the effects of TBC on lipopolysaccharide (LPS)-activated microglial-induced neurotoxicity by using the in vitro model of coculture murine microglial-like cell line HAPI with the neuronal-like human neuroblastoma cell line SH-SY5Y. We also examined the effects of TBC on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in human dopaminergic neuroblastoma SH-SY5Y cells. TBC at concentrations from 0.1-10 microM had no toxic effect on HAPI cells and SH-SY5Y cells, and it inhibited LPS (100 ng/ml)-induced increases of superoxide, intracellular ROS, gp91(Phox), iNOS and a decrease of HO-1 in HAPI cells. Under coculture condition, TBC significantly reduced LPS-activated microglia-induced dopaminergic SH-SY5Y cells death. Moreover, TBC (0.1-10 microM) inhibited 6-OHDA-induced increases of intracellular ROS, iNOS, nNOS, and a decrease of mitochondria membrane potential, and cell death in SH-SY5Y cells. However, the neurotoxic effects of TBC (100 microM) on SH-SY5Y cells were also observed including the decrease in mitochondria membrane potential and the increase in COX-2 expression and cell death. TBC-induced SH-SY5Y cell death was attenuated by pretreatment with NS-398, a selective COX-2 inhibitor. In conclusion, this study suggests that TBC might possess protective effects on inflammation- and oxidative stress-related neurodegenerative disorders. However, the high concentration of TBC might be toxic, at least in part, for increasing COX-2 expression.

Novel 2-(4-methylsulfonylphenyl)pyrimidine derivatives as highly potent and specific COX-2 inhibitors

New series of 2-(4-methylsulfonylphenyl) and 2-(4-sulfamoylphenyl)pyrimidines were synthesized and evaluated for their ability to inhibit cyclooxygenase-2 (COX-2). COX-1 and COX-2 inhibitory activity of these compounds was determined using purified enzyme (PE) and human whole blood (HWB) assays. Extensive structure-activity relationship (SAR) work was carried out within these series, and a wide number of potent and specific COX-2 inhibitors were identified (HWB COX-2 IC(50)=2.4-0.3nM and 80- to 780-fold more selective than rofecoxib).

HIV-1 envelope glycoprotein 120 induces cyclooxygenase-2 expression in astrocytoma cells through a nuclear factor-kappaB-dependent mechanism

Human immunodeficiency virus-1 gp120 alters astroglial function, which compromises the function of the nearby of neuronal cells contributing to the cognitive impairment in human immunodeficiency virus-1 infection. Cyclooxygenase (COX)-2 has been involved in this process, although the intracellular pathways and second messengers involved are yet unknown. We have investigated the role of gp120-induced COX-2 in the astrocytoma human cell line U-87, and the different pathways involved in this activation. COX-2 mRNA and protein expression were detected in gp120-stimulated cells. Moreover, gp120 induces COX-2 promoter transcription. The effect of gp120 was abrogated by a neutralizing antibody against the chemokine receptor CXCR4 neutralizing antibody. Analysis of the promoter show that deletion or mutation of a proximal nuclear factor (NF)-kappaB site completely abrogated gp120-dependent transcription. NF-kappaB but neither Activating protein-1 nor nuclear factor of activated T-cells-dependent transcription was induced by gp120, as shown by reporter and electrophoretic mobility shift assays. In addition, transfection assays with the NF-kappaB inhibitor, IkappaBalpha, prevented gp120-mediated COX-2 induction. In contrast, there was no inhibition of COX-2 promoter transcription by expressing a dominant negative c-Jun, or nuclear factor of activated T-cells constructs. The antioxidant pyrrolidine dithiocarbamate inhibited COX-2 protein expression and COX-2 transcriptional activity induced by gp120. Thus, our results indicate that gp120 induced COX-2 transcription through NF-kappaB activation in astrocytoma cells.

Topical administration of nepafenac inhibits diabetes-induced retinal microvascular disease and underlying abnormalities of retinal metabolism and physiology

Pharmacologic treatment of diabetic retinopathy via eyedrops could have advantages but has not been successful to date. We explored the effect of topical Nepafenac, an anti-inflammatory drug known to reach the retina when administered via eyedrops, on the development of early stages of diabetic retinopathy and on metabolic and physiologic abnormalities that contribute to the retinal disease. Streptozotocin-induced diabetic rats were assigned to three groups (0.3% Nepafenac eyedrops, vehicle eyedrops, and untreated control) for comparison to age-matched nondiabetic control animals. Eyedrops were administered in both eyes four times per day for 2 and 9 months. At 2 months of diabetes, insulin-deficient diabetic control rats exhibited significant increases in retinal prostaglandin E(2), superoxide, vascular endothelial growth factor (VEGF), nitric oxide (NO), cyclooxygenase-2, and leukostasis within retinal microvessels. All of these abnormalities except NO and VEGF were significantly inhibited by Nepafenac. At 9 months of diabetes, a significant increase in the number of transferase-mediated dUTP nick-end labeling-positive capillary cells, acellular capillaries, and pericyte ghosts were measured in control diabetic rats versus nondiabetic controls, and topical Nepafenac significantly inhibited all of these abnormalities (all P < 0.05). Diabetes-induced activation of caspase-3 and -6 in retina was partially inhibited by Nepafenac (all P < 0.05). Oscillatory potential latency was the only abnormality of retinal function reproducibly detected in these diabetic animals, and Nepafenac significantly inhibited this defect (P < 0.05). Nepafenac did not have a significant effect on diabetes-induced loss of cells in the ganglion cell layer or in corneal protease activity. Topical ocular administration of Nepafenac achieved sufficient drug delivery to the retina and diabetes-induced alterations in retinal vascular metabolism, function, and morphology were inhibited. In contrast, little or no effect was observed on diabetes-induced alterations in retinal ganglion cell survival. Local inhibition of inflammatory pathways in the eye offers a novel therapeutic approach toward inhibiting the development of lesions of diabetic retinopathy.

Identification of 2-hydroxymethyl-4-[5-(4-methoxyphenyl)-3-trifluoromethyl-pyrazol-1-yl]-N-propionylbenzenesulfonamide sodium as a potential COX-2 inhibitor for oral and parenteral administration

Synthesis of prodrugs of orally active COX-2 inhibitor 3 involving sulfamoyl (SO(2)NH(2)) and hydroxymethyl (CH(2)OH) groups, and their biological evaluation are described. Of these prodrugs, the N-propionyl sulfonamide sodium 3k was found to be much superior to the parent compound 3 and other marketed COX-2 inhibitors in carrageenan induced rat paw edema model of inflammation due to highly elevated drug levels in systemic circulation. This prodrug has a potential both for oral as well as parenteral administration due to impressive analgesic activity, antipyretic potency, and extraordinary water solubility.

Cyclooxygenase-2-dependent neuronal death proceeds via superoxide anion generation

Cyclooxygenase-2 (COX-2) expression is induced in the neurons of the pathologic brain and elevated COX-2 expressions can lead to neuronal death. Here, we report that COX-2 induction in cortical neurons induced by LPS pretreatment for more than 12 h increased the neurotoxic effects of low doses of Fe2+ by more than 2.5-fold. Moreover, the neurotoxicity induced by 30 muM Fe2+ in LPS-pretreated cells exceeded that induced by 100 microM Fe2+ in LPS-untreated cells. LPS pretreatment also similarly aggravated the neurotoxic effects of low doses of H2O2, Zn2+, and sodium nitroprusside. This LPS-induced Fe2+ -toxicity enhancement was blocked by trolox, vitamin C, the SOD mimetic MnTBAP, and by the COX-2-specific inhibitor NS398, but not by inhibitors of xanthine oxidase, NADPH oxidase, NOS, and monoamine oxidase. Cortical neurons with enhanced COX-2 expression showed superoxide generation, GSH depletion, and lipid peroxidation in response to low doses of Fe2+, and all of these changes were repressed by MnTBAP or NS398. Consistent with this pharmacological data, cortical neurons prepared from COX-2 knockout mice showed marked reductions in LPS-induced Fe2+ -toxicity enhancement and superoxide generation. These results suggest that COX-2 functions as a cellular factor which induces superoxide-mediated cell death in primary cortical neurons.

N-Acylated sulfonamide sodium salt: A prodrug of choice for the bifunctional 2-hydroxymethyl-4-(5-phenyl-3-trifluoromethyl-pyrazol-1-yl) benzenesulfonamide class of COX-2 inhibitors

Synthesis and biological evaluation of possible prodrugs of COX-2 inhibitors involving sulfonamide and hydroxymethyl groups of 2-hydroxymethyl-4-(5-phenyl-3-trifluoromethyl-pyrazol-1-yl) benzenesulfonamides are described. Out of many options, the sodium salt of N-propionyl sulfonamide demonstrated much improved pharmacological profiles and physicochemical properties suitable for oral as well as parenteral administration.

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.

Prostaglandin D2-mediated microglia/astrocyte interaction enhances astrogliosis and demyelination in twitcher

Prostaglandin (PG) D2 is well known as a mediator of inflammation. Hematopoietic PGD synthase (HPGDS) is responsible for the production of PGD2 involved in inflammatory responses. Microglial activation and astrogliosis are commonly observed during neuroinflammation, including that which occurs during demyelination. Using the genetic demyelination mouse twitcher, a model of human Krabbe's disease, we discovered that activated microglia expressed HPGDS and activated astrocytes expressed the DP1 receptor for PGD2 in the brain of these mice. Cultured microglia actively produced PGD2 by the action of HPGDS. Cultured astrocytes expressed two types of PGD2 receptor, DP1 and DP2, and showed enhanced GFAP production after stimulation of either receptor with its respective agonist. These results suggest that PGD2 plays an important role in microglia/astrocyte interaction. We demonstrated that the blockade of the HPGDS/PGD2/DP signaling pathway using HPGDS- or DP1-null twitcher mice, and twitcher mice treated with an HPGDS inhibitor, HQL-79 (4-benzhydryloxy-1-[3-(1H-tetrazol-5-yl)-propyl]piperidine), resulted in remarkable suppression of astrogliosis and demyelination, as well as a reduction in twitching and spasticity. Furthermore, we found that the degree of oligodendroglial apoptosis was also reduced in HPGDS-null and HQL-79-treated twitcher mice. These results suggest that PGD2 is the key neuroinflammatory molecule that heightens the pathological response to demyelination in twitcher mice.