Alternative splicing of platelet cyclooxygenase-2 mRNA in patients after coronary artery bypass grafting

Recently, we cloned from platelet mRNA a novel cyclooxygenase (COX)-2 splice variant, designated COX-2a, which is characterized by a partial deletion of exon 5. Preliminary studies of mRNA distribution of COX-2 isoforms in platelets from coronary artery bypass grafting (CABG) patients showed a variable increase in COX-2a mRNA expression after cardiac surgery. Thus, we assessed whether this variant may play a functional role in these patients. We report a marked (about 200-fold) increase in the expression of COX-2a mRNA after CABG. Evidence is presented that ribosomal frame-shifting may correct the coding sequence resulting in the expression of a full-length COX-2a protein. In addition, a reading frame-corrected COX-2a mutant (COX-2a delta G) was generated by site-directed mutagenesis and expressed in COS-7 cells using an adenoviral expression system. However, COX-2a protein was not active in terms of prostaglandin formation. Thus, alternative mRNA splicing might represent an intriguing posttranscriptional mechanism to oppose a transcriptional activation of the COX-2 gene. Evolutionary, this mechanism may prevent COX-2-dependent thromboxane synthesis in the platelet, which would potentiate the likelihood of thrombosis; pharmacologically, this mechanism would prevent an aspirin-insensitive pathway of thromboxane formation.

Modeling and Simulation to Support Dose Selection and Clinical Development of SC-75416, a Selective COX-2 Inhibitor for the Treatment of Acute and Chronic Pain

Pharmacokinetic/pharmacodynamic (PK/PD) models were developed and clinical trial simulations were conducted to recommend a study design to test the hypothesis that a dose of SC-75416, a selective cyclooxygenase-2 inhibitor, can be identified that achieves superior pain relief (PR) compared to 400 mg ibuprofen in a post-oral surgery pain model. PK/PD models were developed for SC-75416, rofecoxib, valdecoxib, and ibuprofen relating plasma concentrations to PR scores using a nonlinear logistic-normal model. Clinical trial simulations conducted using these models suggested that 360 mg SC-75416 could achieve superior PR compared to 400 mg ibuprofen. A placebo- and positive-controlled parallel-group post-oral surgery pain study was conducted evaluating placebo, 60, 180, and 360 mg SC-75416 oral solution, and 400 mg ibuprofen. The study results confirmed the hypothesis that 360 mg SC-75416 achieved superior PR relative to 400 mg ibuprofen (DeltaTOTPAR6=3.3, P<0.05) and demonstrated the predictive performance of the PK/PD models.

COX-2 expression in atherosclerosis: the good, the bad or the ugly?

Cyclooxygenase (COX) is the rate limiting enzyme catalyzing the conversion of arachidonic acid into prostanoids, lipid mediators critically implicated in a variety of physiological and pathophysiological processes, including inflammation, vascular and renal homeostasis, and immune responses. Since the early 1990s it has been appreciated that two isoforms of COX exist, referred to as COX-1 and COX-2. Although structurally homologous, COX-1 and COX-2 are regulated by two independent and quite different systems and have different functional roles. In the setting of acute ischemic syndromes it has been recognized that COX pathway plays an important role; however, whereas the function of platelet COX-1 in acute ischemic diseases is firmly established, the role of COX-2 in atherothrombosis remains controversial. The complex role of COX-2 in this setting is also confirmed by the unexpected cardiovascular side effects of long-term treatment with COX-2 inhibitors. In this article, we review the pattern of expression of COX-2 in the cellular players of atherothrombosis, its role as a determinant of plaque vulnerability, the effects of the variable expression of upstream and downstream enzymes in the prostanoid biosynthesis on COX-2 expression and inhibition.

Overexpressed cyclo-oxygenase-2 in the background liver is associated with the clinical course of hepatitis C virus-related cirrhosis patients after curative surgery for hepatocellular carcinoma

BACKGROUND

The probable role of cyclo-oxygenase-2 (COX-2) in the development of hepatocellular carcinoma (HCC) in patients with chronic liver diseases has been accepted to be relevant. The purpose of the present study was to determine whether overexpressed COX-2 in the background liver affects the clinical course of hepatitis C virus (HCV)-related cirrhosis patients after curative surgery for HCC.

METHODS

Twenty-nine clinical stage I HCC patients with HCV-related cirrhosis, who underwent curative surgery, were enrolled in the present study (22 men and seven women, age range 53-73 years; follow-up period; range 22-159 months, median 61 months). The COX-2 expression in the cirrhotic liver was examined by immunohistochemistry using the avidin-biotin-peroxidase complex technique on paraffin-embedded formalin-fixed tissue. The COX-2 expression was scored, then correlated with monitored alanine aminotransferase (ALT) levels during the follow-up period after surgery, response to alternative therapy aiming to improve elevated ALT levels, and recurrence/survival after surgery.

RESULTS

The COX-2 expression scores were significantly higher in the high-ALT group than in the low-ALT group (Mann-Whitney, P = 0.010), and were significantly higher in non-responders to the alternative therapy than in responders (Mann-Whitney, P = 0.028). The higher COX-2 expression in the cirrhotic liver was the significant independent risk factor for residual liver recurrence (Cox multivariate analysis, P = 0.014), but not for survival.

CONCLUSIONS

Overexpressed COX-2 in the background liver may play an important role in prolonged acceleration of necroinflammation, resistance to the alternative therapy, and recurrence/new development of HCC in HCV-related cirrhosis patients.

Stored packed red blood cell transfusion up-regulates inflammatory gene expression in circulating leukocytes

SUMMARY BACKGROUND DATA

The transfusion of more than 6 units of packed red blood cells (PRBCs) within the first 12 hours of injury is the strongest independent predictor of multiple organ failure (MOF). This suggests that stored blood contains bioactive factors that may modify the immunoinflammatory response.

METHODS

To simulate postinjury major transfusions ex vivo, we obtained whole blood from 4 healthy adults and divided it into four 7-mL groups (I-IV). Group I was not diluted. Group II had 7 mL of 0.9% sterile saline (SS) added. Group III received 3.5 mL each of leuko-reduced stored PRBC and SS (simulating a major transfusion). Group IV received 3.5 mL each of SS and a hemoglobin-based oxygen carrier (PolyHeme) to evaluate the effects of hemoglobin alone. The hemoglobin content in groups III and IV was measured to be equal. Total leukocyte RNA was purified, and its gene array profiles were obtained.

RESULTS

Of the 56,475 oligonucleotide probe sets interrogated, 415 were statistically different (P < 0.001). Fourteen of the 415 probe sets were inflammatory-related. The PRBC group had a significantly different expression profile compared with the others and included up-regulation of the interleukin-8, toll-like receptor 4, cryropyrin, prostaglandin-endoperoxide synthase-2, and heparinase genes.

CONCLUSIONS

PRBCs activate inflammatory genes in circulating leukocytes, which may be central to the pathogenesis of the adverse inflammatory responses that lead to postinjury MOF.

NMI-1182, a gastro-protective cyclo-oxygenase-inhibiting nitric oxide donor

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to treat inflammation and to provide pain relief but suffer from a major liability concerning their propensity to cause gastric damage. As nitric oxide (NO) is known to be gastro-protective we have synthesized a NO-donating prodrug of naproxen named NMI-1182. We evaluated two cyclo-oxygenase (COX)-inhibiting nitric oxide donors (CINODs), NMI-1182 and AZD3582, for their ability to be gastro-protective compared to naproxen and for their anti-inflammatory activity. NMI-1182 and AZD3582 were found to produce similar inhibition of COX activity to that produced by naproxen. Both NMI-1182 and AZD3582 produced significantly less gastric lesions after oral administration than naproxen. All three compounds effectively inhibited paw swelling in the rat carrageenan paw edema model. In the carrageenan air pouch model all three compounds significantly reduced PGE2 levels in the pouch exudate but only NMI-1182 and naproxen inhibited leukocyte influx. These data demonstrate that NMI-1182 has comparable anti-inflammatory activity to naproxen but with a much reduced likelihood to cause gastric damage.

Dipyrone elicits substantial inhibition of peripheral cyclooxygenases in humans: new insights into the pharmacology of an old analgesic

Dipyrone (INN, metamizol) is a common analgesic used worldwide. Its widespread prescription or over-the-counter use in many countries (e.g., Brazil, Israel, Mexico, Russia, Spain) requires insight into its mode of action. This study therefore addressed the impact of its metabolites 4-methyl-amino-antipyrine (MAA) and 4-amino-antipyrine (AA) on peripheral cyclooxygenases (COX). Pharmacokinetics of metabolites and ex vivo COX inhibition were assessed in five volunteers receiving dipyrone at single oral doses of 500 or 1000 mg. Coagulation-induced thromboxane B2 formation and lipopolysaccharide-induced prostaglandin E2 synthesis were measured in vitro and ex vivo in human whole blood as indices of COX-1 and COX-2 activity. In vitro, metabolites elicited no substantial COX-1/COX-2 selectivity with MAA (IC50=2.55 micromol/L for COX-1; IC50=4.65 micromol/L for COX-2), being approximately 8.2- or 9-fold more potent than AA. After administration of dipyrone, MAA plasma concentrations remained above the IC50 values for each isoform for at least 8 h (500 mg) and 12 h (1000 mg) postdose. COX inhibition correlated with MAA plasma levels (ex vivo IC50 values of 1.03 micromol/L [COX-1] and 0.87 micromol/L [COX-2]). By contrast, plasma peak concentrations of AA after the 1000 mg dose were 2.8- and 6.5-fold below its IC50 values for COX-1 and COX-2, respectively. Maximal inhibitions of COX-1 and COX-2 were 94% and 87% (500 mg), 97% and 94% (1000 mg). Taken together, dipyrone elicits a substantial and virtually equipotent inhibition of COX isoforms via MAA. Given the profound COX-2 suppression by dipyrone, which was considerably above COX-2 inhibition by single analgesic doses of celecoxib and rofecoxib, a significant portion of its analgesic action may be ascribed to peripheral mechanisms. In view of the observed COX-1 suppression, physicochemical factors (lack of acidity) rather than differential COX-1 inhibition may be responsible for dipyrone's favorable gastrointestinal tolerability compared with acidic COX inhibitors.

Interleukin-6 is a candidate molecule that transmits inflammatory information to the CNS

Peripheral inflammation induces reactions within the CNS such as central sensitization, which is involved in the mechanism of inflammatory hyperalgesia. However, the precise mechanism of inflammatory signal transmission from the peripheral inflammatory site to the CNS is not clear. We studied the role of circulating interleukin (IL)-6 as a messenger of inflammatory information from the periphery to the CNS. In the rat model of inflammatory hyperalgesia induced by carrageenan, levels of IL-6 but not IL-1beta or tumor necrosis factor alpha (TNFalpha) were significantly elevated in the circulating blood 3 h after an injection of carrageenan. In addition, injecting carrageenan into the hind paw evoked thermal hyperalgesia and the release of prostaglandin E(2) (PGE(2)) from isolated blood vessels of the CNS ex vivo, as well as the induction of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES)-1 and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) in vascular endothelial cells of the CNS. A prior i.p. injection of IL-6 antiserum (IL-6AS) abolished or attenuated these responses. The present results suggested that circulating IL-6 could act as a messenger of inflammatory information from peripheral inflammatory sites to the CNS and as the afferent circulating signal to the CNS to produce prostaglandins in the vascular endothelial cells of the CNS through a COX-2 dependent pathway.

A randomized, double-blind, one-week study comparing effects of a novel COX-2 inhibitor and naproxen on the gastric mucosa

CS-706 is a novel cyclooxygenase-2 (COX-2) inhibitor with potent analgesic, anti-inflammatory, and antitumor properties in animal models. This one-week, multicenter study was undertaken to assess the safety and tolerability of CS-706 and to compare the effects of CS-706 versus naproxen on acute gastrointestinal (GI) mucosal injury. Healthy men and women (n=160) without evidence of underlying gastroduodenal lesions were randomized to placebo, 100 mg CS-706 once daily, 200 mg CS-706 once daily, or 500 mg naproxen twice daily, administered for 7 days. On Day 8, subjects underwent a posttreatment upper GI endoscopy to assess development of gastroduodenal petechiae, erosions, and ulcers. Inhibition of COX-1 and COX-2 activity over the 24-hr postdose interval on Day 7 was determined in 48 subjects (12 per treatment group). CS-706 was safe and well tolerated. The extent of upper GI mucosal injury for both CS-706 dose groups was statistically significantly less than that for naproxen (P < 0.001) and was similar to placebo (P=0.615 and P=0.115 for 100 and 200 mg CS-706, respectively). No subject in placebo or either CS-706 treatment group had gastroduodenal ulcers, compared with 11 (28.2%) subjects treated with naproxen (P < 0.001). Both doses of CS-706 inhibited COX-2 activity to a similar extent as naproxen, whereas neither dose of CS-706 showed meaningful inhibition of platelet COX-1. In contrast, naproxen nearly completely inhibited COX-1 over the dosing interval. We conclude that CS-706, dosed up to 200 mg once daily, has an acute, upper GI toxicity profile similar to that of placebo and significantly superior to that of naproxen.

Expression of cyclooxygenase-2 mRNA in peripheral blood of head and neck cancer patients and in healthy controls. A pilot study

CONCLUSIONS

Cyclooxygenase-2 mRNA (COX2) levels are higher in head and neck cancer (HNC) patients than in controls and this correlates with tumor size and outcome. These findings suggest the use of this parameter as a future tumor marker.

OBJECTIVE

We analyzed the expression of COX2 mRNA in peripheral blood cells in HNC patients and in healthy controls and its relationship with outcome and progression-free survival.

MATERIALS AND METHODS

Blood samples were obtained from 41 consecutive HNC patients and 16 healthy controls and analyzed for COX2 mRNA with quantitative real-time polymerase chain reaction and compared with beta-actin as a house-keeping gene.

RESULTS

Treatment consisted of surgery only (4 patients), chemoradiotherapy (18), chemotherapy followed by curative surgery (4) or palliative chemotherapy (15). COX2 mRNA levels were higher in patients with unfavorable outcome (mean 6.8, median 2.06) than those with favorable outcome (mean 1.2, median 1.31) (p=0.062). Both were higher than for healthy controls (mean 0.74, median 0.72; p<0.001). In bulky tumors, the percentage of level over 6 in unfavorable outcome cases was higher than in the favorable outcome cases (p=0.005). In chemotherapy patients with level <or=1 no relapse or progression was observed (n=7), and progression-free survival was significantly better than those with level >1 (n=19) (p=0.0138).

Altered monocyte cyclooxygenase response to lipopolysaccharide in type 1 diabetes

Type 1 diabetes is caused by adaptive immune responses, but innate immunity is important because monocytes infiltrate islets. Activated monocytes express cyclooxygenase (COX)-2, promoting prostaglandin-E(2) (PGE(2)) secretion, whereas COX-1 expression is constitutive. We aimed to define monocyte COX expression in type 1 diabetes basally and after lipopolysaccharide (LPS) stimulation. Isolated CD14(+) monocytes were analyzed for COX mRNA and protein expression from identical twins (discordant for type 1 diabetes) and control subjects. Basal monocyte COX mRNA, protein expression, and PGE(2) secretion were normal in type 1 diabetic subjects. After LPS, twins and control subjects showed a COX mRNA isoform switch with decreased COX-1 mRNA (P < 0.01), increased COX-2 mRNA (P < 0.01), and increased COX-2 protein expression (P < 0.01). Compared with control subjects, both diabetic and nondiabetic twins showed greater LPS-induced downregulation of monocyte COX-1 mRNA (P = 0.02), reduced upregulation of COX-2 mRNA and protein (P < 0.03), and greater inhibition by the COX-2 inhibitor di-isopropylfluorophosphate (DFP) of monocyte PGE(2) (P < 0.007). We demonstrate an alteration in monocyte COX mRNA expression as well as monocyte COX-2 and PGE(2) production after LPS in type 1 diabetic patients and their nondiabetic twins. Because COX-2 response to LPS is proinflammatory, an inherited reduced response would predispose to chronic inflammatory diseases such as type 1 diabetes.

Anti-inflammatory effects of 4-phenyl-3-butenoic acid and 5-(acetylamino)-4-oxo-6-phenyl-2-hexenoic acid methyl ester, potential inhibitors of neuropeptide bioactivation

Substance P (SP) and calcitonin gene-related peptide (CGRP) are well established mediators of inflammation. Therefore, inhibition of the biosynthesis of these neuropeptides is an attractive potential strategy for pharmacological intervention against a number of inflammatory diseases. The final step in the biosynthesis of SP and CGRP is the conversion of their glycine-extended precursors to the active amidated peptide, and this process is catalyzed by sequential action of the enzymes peptidylglycine alpha-monooxygenase (PAM) and peptidylamidoglycolate lyase. We have demonstrated previously that 4-phenyl-3-butenoic acid (PBA) is a PAM inhibitor, and we have also shown that in vivo inhibition of serum PAM by PBA correlates with this compound's ability to inhibit carrageenan-induced edema in the rat. Here we demonstrate the ability of PBA to inhibit all three phases of adjuvant-induced polyarthritis (AIP) in rats; this represents the first time that an amidation inhibitor has been shown to be active in a model of chronic inflammation. We recently introduced 5-(acetylamino)-4-oxo-6-phenyl-2-hexenoic acid (AOPHA) as one of a new series of mechanism-based amidation inhibitors. We now report for the first time that AOPHA and its methyl ester (AOPHA-Me) are active inhibitors of serum PAM in vivo, and we show that AOPHA-Me correspondingly inhibits carrageenan-induced edema in rats in a dose-dependent manner. Neither PBA nor AOPHA-Me exhibits significant cyclooxygenase (COX) inhibition in vitro; thus, the anti-inflammatory activities of PBA and AOPHA-Me are apparently not a consequence of COX inhibition. We discuss possible pharmacological mechanisms that may account for the activities of these new anti-inflammatory compounds.

Dual, but not selective, COX-1 and COX-2 inhibitors, attenuate acetic acid-evoked bladder irritation in the anaesthetised female cat

Non-selective cyclooxygenase (COX) inhibitors exert effects on lower urinary tract function in several species. The exact contributions of COX-1 and COX-2 isozymes have not been studied much. The present studies investigated the effects of non- and selective COX inhibitors on bladder irritation in the cat.Chloralose-anaesthetised female cats were catheterised through the bladder dome for cystometric evaluation of bladder responses to intravesical infusion of saline or acetic acid. Bladder capacity, voiding efficiency, threshold pressure, and reflex-evoked bladder contraction amplitude and duration were measured. The cat COX selectivity of the doses of inhibitors examined was determined using an in vitro whole-blood assay and analysis of plasma levels. Pretreatment with indomethacin or ketoprofen (non-selective COX inhibitors; 0.3 mg kg(-1) i.v.) inhibited acetic acid-evoked irritation (characterised by a decrease in bladder capacity in vehicle pretreated animals). FR-122047 (selective COX-1 inhibitor), NS-398 and nimesulide (selective COX-2 inhibitors; 1 and 3 mg kg(-1) i.v.) had no effects on bladder irritation. Analysis of plasma levels of the doses examined and determination of COX-1 and COX-2 inhibition in cat whole blood confirmed the reported selectivity of these compounds in this species. The present studies suggest that dual COX inhibition is required to attenuate acetic acid-evoked bladder irritation in the cat.

[Study of relationship between cyclooxygenase and platelet-activating factor on peripheral blood mononuclear cells in patients with systemic inflammatory response syndrome and multiple organ dysfunction syndrome]

OBJECTIVE

To study the role of cyclooxygenase (COX) and platelet-activating factor (PAF) in pathophysiologic mechanisms of patients with systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS).

METHODS

Twenty-eight adult patients whose diagnosis met American college of chest physicians/society of critical care medicine (ACCP/SCCM) criteria for SIRS and MODS were enrolled for study including 13 cases for SIRS group and 15 cases for MODS group. The normal control group consisted of 11 healthy volunteers who matched with study subjects for age and gender. Enzyme linked immunoadsorbent assay (ELISA) was used to measure the content of COX-2 and the activity of platelet-activating factor acetylhydrolase (PAF-AH) of peripheral blood mononuclear cells (PBMCs). Reverse transcription polymerase chain reaction (RT-PCR) was used to measure the COX-2 mRNA and PAF-AH mRNA expression of PBMCs.

RESULTS

The content of COX-2 and the activity of PAF-AH of PBMCs and the expression of their mRNA in MODS group were higher than those in SIRS group and control group (all P<0.05). There was no significant difference between SIRS group and control group. The content of COX-2 and the activity of PAF-AH and the expression of their mRNA of PBMCs in non-survivors were higher than those in survived patients (all P<0.05). In 3 groups, positive correlation was found between the COX-2 content and PAF-AH activity (r=0.329, P<0.05). The leukocyte count, lymphocyte count, and PaO(2)/FiO(2) of peripheral blood in non-survivors showed no significant difference with those of survived patients (all P>0.05). The blood glucose and creatinine of non-survivors were higher than those of survived patients (P<0.05 and P<0.01). The total CO(2) content (TCO(2)) and pH value of non-survivors were lower than those of survived patients (both P<0.01).

CONCLUSION

This study shows that COX-2 and PAF-AH play a role in the occurrence of MODS and they can be used as indexes to judge the prognosis of SIRS and MODS. Blood glucose, creatinine, TCO(2) and pH value of blood can be used as other indexes for judging the state and the prognosis of the illness.

COX-2 and preoperative CA-125 level are strongly correlated with survival and clinical responsiveness to chemotherapy in ovarian cancer

BACKGROUND

CA-125 is elevated in the serum of the majority of ovarian carcinoma patients. Cyclooxygenase-2 is an enzyme whose synthesis is upgraded by several cytokines, growth factors, and tumor promoters.

METHODS

We analyzed cyclooxygenase-2, preoperative CA-125 levels, and CA-125 levels during chemotherapy in 41 FIGO stage III, grade 3, ovarian serous carcinoma patients in relation to survival with a logistic regression. The correlation of cyclooxygenase-2 expression and CA-125 preoperative level with clinical responsiveness to chemotherapy was studied according to Fisher's exact test. We compared 23 patients living with no evident disease five years after primary treatment to 18 patients who had died of progression of disease no later than two years after primary treatment.

RESULTS

Cyclooxygenase-2 overexpression (p = 0.014 and p = 0.036) and preoperative CA-125 level (p = 0.012 and p = 0.029) were found to be independent predictors of survival in univariate and multivariate analyses. Cyclooxygenase-2 and CA-125 level were correlated to responsiveness to chemotherapy (p = 0.003 and p = 0.036, respectively; Fisher's exact test). The patients with a CA-125 level <35 U/ml after two cycles of chemotherapy showed a longer survival (p = 0.008). The median preoperative CA-125 was 195 in high survival patients and 650 in low survival patients (p= 0.004, Wilcoxon Mann-Whitney test).

CONCLUSIONS

Cyclooxygenase-2 overexpression and CA-125 levels may help the management of ovarian cancer patients, permitting the selection of more aggressive and tailored first-line therapy.

Suppression of prostaglandin E2 by malaria parasite products and antipyretics promotes overproduction of tumor necrosis factor-alpha: association with the pathogenesis of childhood malarial anemia

Cytokines and effector molecules are important immunoregulatory molecules in human malaria. Tumor necrosis factor (TNF)-alpha limits malaria parasitemia but also promotes pathogenesis at high concentrations, whereas prostaglandin E2 (PGE2) inhibits TNF-alpha production and is reduced in childhood malaria, at least in part, through suppression of cyclooxygenase (COX)-2 following the ingestion of Plasmodium falciparum hemozoin (pfHz; malarial pigment) by peripheral blood mononuclear cells (PBMCs). Although molecular interactions between TNF-alpha and PGE2 are largely unexplored in human malaria, results presented here show that pfHz-induced suppression of PBMC COX-2 gene products induces overproduction of TNF-alpha. Moreover, addition of exogenous PGE2 to pfHz-treated PBMCs dose-dependently decreased TNF-alpha production, whereas experimental COX inhibitors and antipyretics used during human malaria generated increased TNF-alpha production. Healthy, malaria-exposed children had elevated levels of circulating bicyclo-PGE2/TNF-alpha, compared with children with malarial anemia (P<.01), with systemic bicyclo-PGE2 and TNF-alpha significantly associated with hemoglobin concentrations (r=0.745; P<.01). The results of the present study illustrate that pfHz-induced suppression of PGE2 promotes overproduction of TNF-alpha, which is associated with enhanced malarial anemia.

Immune modulatory effects of cyclooxygenase type 2 inhibitors in HIV patients on combination antiretroviral treatment

OBJECTIVES

To examine the immune modulating effects of cyclooxygenase type 2 (COX-2) inhibitors (COX-2i) in HIV-infected patients on combination antiretroviral treatment (CART).

DESIGN

In-depth substudy from an approved, open, controlled, randomized study comparing the immune modulating effects of CART in combination with COX-2i after 12 weeks.

METHODS

Patients (n = 38) on long-term CART with stable viral load (VL) < 50,000 copies/ml and CD4+ T-cell counts > 100/microl were randomized to CART and rofecoxib 25 mg bid (n = 12) or celecoxib 400 mg bid (n = 12), or CART only without placebo (n = 14). Routine clinical chemistry, CD4+ and CD8+ counts and VL were safety parameters. Immunological parameters included C-reactive protein, beta2-microglobulin, Ig isotypes and IgG subclasses as well as several T-lymphocyte subsets. Non-parametric analyses were used throughout.

RESULTS

Prestudy experiments showed higher median intracellular expression of COX-2 in CD4+ (P = 0.048) and possibly CD8+ (P = 0.09) T cells from patients on CART compared with uninfected controls. In the clinical study, increased CD4+ T-cell counts were observed only in patients on COX-2i with VL < 50 copies/ml (P = 0.02). Decreased expression of CD38+ on CD8+ T cells and subsets as well as reductions in IgA and IgM (P < 0.03) were most pronounced in patients on COX-2i who had detectable VL (n = 6). COX-2i treatment enhanced the perforin content particularly in the differentiated CD27-/CD8+ T-cell subsets compared with controls (P = 0.05).

CONCLUSIONS

COX-2i together with CART improved markers for persistent immune activation, particularly in patients with viraemia, as well as enhanced perforin expression, and thereby strengthened COX-2 as a potential therapeutic target in HIV infection.

Obese state leads to elevated levels of TGF-β and COX isoforms in platelets of Zucker rats

Platelets are rich sources of growth factors and enzymes that are implicated in a number of diseases including obesity, atherosclerosis, heart disease, syndrome X, liver and kidney diseases and certain types of cancers. In this research we investigated, if platelets in Zucker obese rats differ from their lean counterparts with respect to the levels of TGF-beta and COX isoforms, implicated in the pathogenesis of chronic diseases. In addition, we investigated if energy intake of the animals affects the platelet physiology. Platelets were isolated from obese and lean rats bearing preneoplastic lesions in their colon. Prior to platelet isolation these rats were fed either ad libitum (Ob or Ln) or energy restricted (Ob-ER or Ln-ER) diets for 8 weeks (n = 8/group). The levels of TGF-beta1/-beta2 and COX-1/-2 proteins in platelets were analyzed by Western blot. The platelets of the Ob rats had significantly higher levels of TGF-beta1, COX-1/-2 (p < 0.001) than did the platelets of the Ln rats and were not affected by moderate energy restriction. There were no significant differences in the protein expression of platelet TGF-beta2 among any of the groups. These results demonstrate that cytokines and candidates playing a role in the pathogenesis of chronic diseases, such as TGF-beta1 and COX-1/-2, are over-expressed in platelets of Zucker obese rats by comparison to their lean counterparts. These findings also demonstrate that the genotype of the animals exerts a significant effect on the biochemical composition of the platelets and could contribute to the pathogenesis of colon cancer and other metabolic abnormalities associated with obesity.

Direct and irreversible inhibition of cyclooxygenase-1 by nitroaspirin (NCX 4016)

Benzoic acid, 2-(acetyl-oxy)-3-[(nitrooxy)methyl]phenyl ester (NCX 4016), a new drug made by an aspirin molecule linked, through a spacer, to a nitric oxide (NO)-donating moiety, is now under clinical testing for the treatment of atherothrombotic conditions. Aspirin exerts its antithrombotic activity by irreversibly inactivating platelet cyclooxygenase (COX)-1. NCX 4016 in vivo undergoes metabolism into deacetylated and/or denitrated metabolites, and it is not known whether NCX 4016 needs to liberate aspirin to inhibit COX-1, or whether it can block it as a whole molecule. The aim of our study was to evaluate the effects of NCX 4016 and its analog or metabolites on platelet COX-1 and whole blood COX-2 and on purified ovine COX (oCOX)-1 and oCOX-2. In particular, we have compared the mechanism by which NCX 4016 inhibits purified oCOX enzymes with that of aspirin using a spectrophotometric assay. All the NCX 4016 derivatives containing acetylsalicylic acid inhibited the activity of oCOX-1 and oCOX-2, whereas the deacetylated metabolites and the nitric oxide-donating moiety were inactive. Dialysis experiments showed that oCOX-1 inhibition by NCX 4016, similar to aspirin, is irreversible. Reversible COX inhibitors (indomethacin) or salicylic acid incubated with the enzyme before NCX 4016 prevent the irreversible inhibition of oCOX-1 by NCX 4016 as well as by aspirin. In conclusion, our data show that NCX 4016 acts as a direct and irreversible inhibitor of COX-1 and that the presence of a spacer and NO-donating moiety in the molecule slows the kinetics of COX-1 inhibition by NCX 4016, compared with aspirin.

Increased expression of nitric oxide synthase and cyclooxygenase-2 is associated with poor survival in cervical cancer treated with radiotherapy

PURPOSE

To investigate the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in cervical cancer and their association with clinical outcome in patients treated with radical radiotherapy.

METHODS AND MATERIALS

One hundred sixty-seven consecutive patients with FIGO Stages IB-IVA squamous cell cervical cancer underwent radical radiotherapy, including external-beam radiotherapy or high-dose-rate brachytherapy, or both, between 1989 and 2002. Immunohistochemical studies of their formalin-fixed, paraffin-embedded tissues were performed. Univariate and multivariate analyses were performed to identify and evaluate the effects of the factors affecting patient survival.

RESULTS

Positive immunostainings of iNOS and COX-2 were observed in 58.7% and 64.1% of the participants, respectively. The expression of both iNOS and COX-2 was positively correlated (Spearman correlation coefficient = 0.49, p < 0.01), and their overexpression provided independent predictors of distant metastasis (odds ratio = 5.22 and 10.07, respectively; p < 0.01 for all). iNOS- and COX-2-expressing patients had significantly shorter disease-free survival (p < 0.01, both) and cause-specific overall survival (p = 0.01, p < 0.01, respectively). Patients with iNOS-positive/COX-2-positive tumors had the poorest survival rates. Coexpression of iNOS/COX-2, together with bulky tumor and advanced stage were independent prognostic factors for disease-free survival.

CONCLUSION

Overexpression of iNOS or COX-2 or both was associated with decreased survival and a greater propensity to metastasize in cervical cancer patients treated with radiotherapy. Coexpression of iNOS and COX-2 may represent a useful biologic marker in patients receiving radical radiotherapy for cervical cancer.