Clinical potential of cyclo-oxygenase-2 inhibitors

Drug Targets for Cardiovascular-Safe Anti-Inflammatory: In Silico Rational Drug Studies

Cyclooxygenase-2 (COX-2) plays an important role in memory consolidation and synaptic activity, the most fundamental functions of the brain. It converts arachidonic acid to prostaglandin endoperoxide H2. In contrast, if over-expressed, it causes inflammation in response to cytokine, pro-inflammatory molecule, and growth factor. Anti-inflammatory agents, by allosteric or competitive inhibition of COX-2, alleviate the symptoms of inflammation. Coxib family drugs, particularly celecoxib, are the most famous anti-inflammatory agents available in the market showing significant inhibitory effect on COX-2 activity. Due to high cardiovascular risk of this drug group, recent researches are focused on the investigation of new safer drugs for anti-inflammatory diseases. Natural compounds, particularly, phytochemicals are found to be good candidates for drug designing and discovery. In the present study, we performed in silico studies to quantitatively scrutinize the molecular interaction of curcumin and its structural analogs with COX-2, COX-1, FXa and integrin αIIbβIII to investigate their therapeutic potential as a cardiovascular-safe anti-inflammatory medicine (CVSAIM). The results of both ADMET and docking study indicated that out of all the 39 compounds studied, caffeic acid had remarkable interaction with proteins involved in inflammatory response. It was also found to inhibit the proteins that are involved in thrombosis, thereby, having the potential to be developed as therapeutic agent.

In Silico Augmentation of the Drug Development Pipeline: Examples from the study of Acute Inflammation

The clinical translation of promising basic biomedical findings, whether derived from reductionist studies in academic laboratories or as the product of extensive high-throughput and -content screens in the biotechnology and pharmaceutical industries, has reached a period of stagnation in which ever higher research and development costs are yielding ever fewer new drugs. Systems biology and computational modeling have been touted as potential avenues by which to break through this logjam. However, few mechanistic computational approaches are utilized in a manner that is fully cognizant of the inherent clinical realities in which the drugs developed through this ostensibly rational process will be ultimately used. In this article, we present a Translational Systems Biology approach to inflammation. This approach is based on the use of mechanistic computational modeling centered on inherent clinical applicability, namely that a unified suite of models can be applied to generate in silico clinical trials, individualized computational models as tools for personalized medicine, and rational drug and device design based on disease mechanism.

The effects of COX-1 and COX-2 inhibitors on prostaglandin synthesis and the formation of heterotopic bone in a rat model

INTRODUCTION

Traumatic heterotopic ossification (HO) is a common clinical condition associated with various orthopedic procedures that involve injury to soft tissues near bone. In this study, we tested the hypothesis that the prophylactic effects of NSAID's in the treatment of HO are mediated via inhibition of the COX-2 enzyme. Here we describe a rat model that simulates HO in the human that was used to test the above hypothesis.

MATERIALS AND METHODS

Heterotopic ossification was surgically induced in the quadriceps by injury to the muscle and femoral periosteum and transplantation of donor bone marrow cells containing osteoprogenitors into the site of injury. HO was imaged and quantified by micro-CT scanning of femurs removed from sacrificed animals at 6 weeks post-injury, three-dimensional computer reconstructions of the scanned bones and computer-assisted morphometric analysis. Prostaglandin E(2) (PGE(2)) synthesis was quantified using an enzyme immunoassay system. The effects of a nonselective COX inhibitor or specific inhibitors of COX-1 or COX-2 following oral administration on the content of ectopic bone and PGE(2) were also measured.

RESULTS

Micro-CT and histological analyses demonstrated that all of the femurs in operated limbs developed HO in the vastus lateralis muscle belly of the quadriceps close to the anterior femur. Only the COX-1,2 nonselective and COX-2 inhibitors significantly decreased HO formation (by about one-third in each case; P < 0.05). PGE(2) synthesis at the site of injury was increased 50- and 100-fold (to 25 ng/g tissue) within 1 and 7 days, respectively, post-injury with the levels declining to near baseline within 2 weeks of surgery. Both the COX-1,2 nonselective and COX-2 inhibitors significantly decreased PGE(2) levels to 25% of control HO levels within 24 h of the first administration, even at low dosages. The COX-1 inhibitor only produced the same effect after 1 week of administration.

CONCLUSION

These findings suggest that although inhibitors of COX-2 or COX-1 reduced PGE(2) synthesis, only the COX-2 enzyme plays a role in the mechanism of traumatic HO.

Effects of cyclooxygenase-1 and -2 inhibition on gastric acid secretion and cardiovascular functions in rats

The discovery of a second isoform of cyclooxygenase has led to a re-evaluation of the mechanisms underlying the adverse effects of nonsteroidal anti-inflammatory drugs, focusing in particular on the gastrointestinal system. We investigated the involvement of cyclooxygenase-1 and -2 in the regulation of gastric acid secretion and cardiovascular functions in anesthetized rats, after acute intravenous administration of the selective cyclooxygenase-1 inhibitor SC-560, the selective cyclooxygenase-2 inhibitor celecoxib and the nonselective inhibitor indomethacin. Indomethacin, celecoxib and SC-560 did not significantly modify basal acid secretion. Indomethacin and celecoxib were also ineffective on the acid secretion stimulated by pentagastrin; by contrast, SC-560 significantly enhanced the acid secretion stimulated by pentagastrin, electrical vagal stimulation or histamine. The stimulatory effects of SC-560 were prevented by cervical vagotomy, atropine and famotidine. Indomethacin caused either no change, increasing or decreasing effects on mean arterial pressure and heart rate. By contrast, SC-560 was unable to change cardiovascular parameters at 5 mg/kg, while inducing a marked bradycardia at 10 mg/kg. Celecoxib was ineffective. Our findings indicate that cyclooxygenase-1-derived prostaglandins are involved in the regulation of stimulated acid secretion and of basal heart rate; the role of prostaglandins in the acute control of systemic blood pressure under resting conditions seems to be negligible.

Influence of glutathione S-transferase pi and p53 expression on tumor frequency and spectrum in mice

The role of glutathione S-transferase pi (GSTpi) in tumor development has been previously suggested; however the exact function of this enzyme in carcinogenesis remains unclear. GSTpi has been identified as a modulator of cell signaling by interacting with and inhibiting c-Jun N-terminal kinase (JNK). This kinase has been in turn described as a regulator of p53 stability and transcriptional activity. To study the possible interaction between GSTpi and p53, we crossed GSTpi-deficient animals with p53(-/-) mice. Double knock out animals were viable but developed tumors within 6 months of age; the life span of these animals was however similar to that of GSTpi(+/-)/p53(-/-) and GSTpi(+/+)/p53(-/-). Mice heterozygous for p53 lived significantly longer than the p53(-/-) animals and developed tumors much later, and the expression of GSTpi did not significantly modify the life span of the animals. In contrast, in a wild-type p53 background, GSTpi(-/-) mice developed tumors with a significantly higher frequency than heterozygous and wild-type animals with a median tumor free life span 20 weeks shorter. In addition, in p53(+/+) background, one third of the GSTpi(-/-) animals developed lung adenomas, while less than 10% of GSTpi(+/-) and GSTpi(+/+) presented such tumors. GSTpi expression did not alter the expression of tumorigenesis markers such as COX-2 or ornithine decarboxylase in response to phorbol ester. Furthermore, GSTpi-deficient mouse embryo fibroblasts were more sensitive to H(2)O(2)-induced apoptosis. P53(-/-) cells, independent of GSTpi status, were more sensitive to UV and other DNA damaging agents than their wild-type counterparts. These results suggest that GSTpi may play a protective role in the development of spontaneous tumors.

Prostaglandin endoperoxide H synthase inhibitors and other tocolytics in preterm labour

Preterm delivery (<37 weeks of gestation) is the major obstetrical complication in developed countries, yet attempts to delay labour and prolong pregnancy have largely been unsuccessful. One of the many reasons it is so difficult to prevent preterm birth is that the nature of preterm labour changes as a function of gestational age, maternal lifestyle factors or infection, to list a few of the reasons. The inhibitors of prostaglandin endoperoxide H synthase (PGHS), known as the Non-steroidal Antiinflammatory Drugs, have been viewed with interest as tocolytics with promising effectiveness under most conditions of preterm labour. Three isoforms of PGHS exist; the first two, PGHS-1 and -2, have been studied for their catalytic activity, X-ray crystallographic structure, and physiological roles in the adult and the foetus. Mixed inhibitors and isoform-specific inhibitors of PGHS have been developed, and their roles in delaying preterm labour are examined and compared to other tocolytics.

Gastroprotection by coxibs: what do the Celecoxib Long-Term Arthritis Safety Study and the Vioxx Gastrointestinal Outcomes Research Trial tell us?

Current evidence suggests that PPIs might be effective in maintaining patients in remission during continued NSAID use and that the combination of omeprazole plus diclofenac is as effective as treatment with celecoxib in preventing recurrent bleeding. Larger outcome studies comparing the combination of a PPI with other nonselective NSAIDs and a selective COX-2 inhibitor (and the combination of a selective COX-2 inhibitor with a PPI or misoprostol) are required to determine whether or not any regimen will further decrease or eliminate the risk of ulcer complications in high-risk individuals.

Nonsteroidal anti-inflammatory drug use and the risk for Alzheimer's disease: dissecting the epidemiological evidence

Inflammation is hypothesised to contribute to the genesis of pathology causing or contributing to Alzheimer's disease (AD). As a part of the immune response in the brain, the prostaglandin pathway is induced; this pathway is the target for NSAIDs, the most widely used anti-inflammatory medication. There are many epidemiological studies, which are reviewed here, suggesting NSAIDs reduce the risk for AD. The most recent of these studies suggest NSAIDs should be taken for at least 2 years. There are little data in humans about whether one type of NSAID is more effective than another. To date, randomised, double-blind, clinical trials in patients with AD have been negative. There is one prevention trial that will yield valuable information about the efficacy of NSAIDs in slowing down the progression of, or preventing, AD. At present, no recommendations can be made concerning the when, what, who and for how long a person should take an NSAID to reduce his or her risk for AD.

Cyclooxygenase-2: from arthritis treatment to new indications for the prevention and treatment of cancer

The discovery of the isoenzymes cyclooxygenase-(COX-) 1 and COX-2 led to the development of newer nonsteroidal anti-inflammatory drugs (NSAIDs) designed to block COX-2, such as rofecoxib, celecoxib, and valdecoxib. Because of the specificity of COX-2 expression, COX-2 inhibitors have the potential to reduce the risk of gastrointestinal bleeding experienced with the use of classic NSAIDs. With their crucial role in the control of inflammation, the COX-2 agents originally were marketed for the treatment of rheumatoid and osteoarthritis. However, promising new indications for COX-2 agents in the prevention and treatment of cancer are under investigation. The role of aberrant COX-2 expression in the development of cancer has been studied most widely in patients with colon cancer and adenomas. Recent studies suggest that COX-2-derived prostaglandins may play an important role in tumor viability, growth, and control of metastasis. Possible new indications for the use of COX-2 inhibitors to prevent and treat cancers may be monumental. However, therapy with these agents is not without risk. Oncology nurses must be aware of the potential problems inherent in the use of COX-2 as well as COX-2 agents for chemoprevention in certain cancers.

Gene expression profiling of 12633 genes in Alzheimer hippocampal CA1: transcription and neurotrophic factor down-regulation and up-regulation of apoptotic and pro-inflammatory signaling

Alterations in transcription, RNA editing, translation, protein processing, and clearance are a consistent feature of Alzheimer's disease (AD) brain. To extend our initial study (Alzheimer Reports [2000] 3:161-167), RNA samples isolated from control and AD hippocampal cornu ammonis 1 (CA1) were analyzed for 12633 gene and expressed sequence tag (EST) expression levels using DNA microarrays (HG-U95Av2 Genechips; Affymetrix, Santa Clara, CA). Hippocampal CA1 tissues were carefully selected from several hundred potential specimens obtained from domestic and international brain banks. To minimize the effects of individual differences in gene expression, RNA of high spectral quality (A(260/280) > or= 1.9) was pooled from CA1 of six control or six AD subjects. Results were compared as a group; individual gene expression patterns for the most-changed RNA message levels were also profiled. There were no significant differences in age, postmortem interval (mean < or = 2.1 hr) nor tissue pH (range 6.6-6.9) between the two brain groups. AD tissues were derived from subjects clinically classified as CDR 2-3 (CERAD/NIA). Expression data were analyzed using GeneSpring (Silicon Genetics, Redwood City, CA) and Microarray Data Mining Tool (Affymetrix) software. Compared to controls and 354 background/alignment markers, AD brain showed a generalized depression in brain gene transcription, including decreases in RNA encoding transcription factors (TFs), neurotrophic factors, signaling elements involved in synaptic plasticity such as synaptophysin, metallothionein III, and metal regulatory factor-1. Three- or morefold increases in RNAs encoding DAXX, cPLA(2), CDP5, NF-kappaBp52/p100, FAS, betaAPP, DPP1, NFIL6, IL precursor, B94, HB15, COX-2, and CEX-1 signals were strikingly apparent. These data support the hypothesis of widespread transcriptional alterations, misregulation of RNAs involved in metal ion homeostasis, TF signaling deficits, decreases in neurotrophic support and activated apoptotic and neuroinflammatory signaling in moderately affected AD hippocampal CA1.