Cyclooxygenase-2 Inhibitors Enhance Shear Stress-Induced Platelet Aggregation

Platelet zinc status regulates prostaglandin-induced signaling, altering thrombus formation

BACKGROUND

Approximately 17.3% of the global population exhibits an element of zinc (Zn2+) deficiency. One symptom of Zn2+ deficiency is increased bleeding through impaired hemostasis. Platelets are crucial to hemostasis and are inhibited by endothelial-derived prostacyclin (prostaglandin I2 [PGI2]), which signals via adenylyl cyclase (AC) and cyclic adenosine monophosphate signaling. In other cell types, Zn2+ modulates cyclic adenosine monophosphate concentrations by changing AC and/or phosphodiesterase activity.

OBJECTIVES

To investigate if Zn2+ can modulate platelet PGI2 signaling.

METHODS

Platelet aggregation, spreading, and western blotting assays with Zn2+ chelators and cyclic nucleotide elevating agents were performed in washed platelets and platelet-rich plasma conditions. In vitro thrombus formation with various Zn2+ chelators and PGI2 was assessed in whole blood.

RESULTS

Incubation of whole blood or washed platelets with Zn2+ chelators caused either embolization of preformed thrombi or reversal of platelet spreading, respectively. To understand this effect, we analyzed resting platelets and identified that incubation with Zn2+ chelators elevated pVASPser157, a marker of PGI2 signaling. In agreement that Zn2+ affects PGI2 signaling, addition of the AC inhibitor SQ22536 blocked Zn2+ chelation-induced platelet spreading reversal, while addition of Zn2+ blocked PGI2-mediated platelet reversal. Moreover, Zn2+ specifically blocked forskolin-mediated AC reversal of platelet spreading. Finally, PGI2 inhibition of platelet aggregation and in vitro thrombus formation was potentiated in the presence of low doses of Zn2+ chelators, increasing its effectiveness in inducing platelet inhibition.

CONCLUSION

Zn2+ chelation potentiates platelet PGI2 signaling, elevating PGI2's ability to prevent effective platelet activation, aggregation, and thrombus formation.

Platelet Adhesion Mediated by von Willebrand Factor at High Shear Rates Is Associated with Premature Coronary Artery Disease

This study investigated von Willebrand factor (VWF)-mediated platelet adhesion at high shear rates in patients with premature coronary artery disease (CAD). The study included 84 patients with stable premature CAD and 64 patients without CAD. Whole blood samples were perfused through a microfluidic cell over a collagen-coated surface at a shear rate of 1300 s^-1. Measurements were performed before and after the inhibition of VWF-specific platelet GPIb receptors with an anti-GPIb monoclonal antibody (mAb). Platelet adhesion decreased by 77.0% (55.9; 84.7) in patients with premature CAD and by 29.6% (0.0; 59.7) in control patients after the inhibition of VWF-platelet interaction with anti-GPIb mAb (p < 0.001). After adjusting for traditional risk factors, the odds ratio for premature CAD per 1% decrease in GPIb-mediated platelet adhesion was 1.03 (95% CI, 1.02-1.05; p < 0.001). The optimal cut-off level value of GPIb-mediated platelet adhesion was 62.8%, with 70.2% sensitivity and 81.2% specificity for CAD. The plasma levels of VWF or antiplatelet therapy did not affect the GPIb-mediated component of platelet adhesion. Thus, the GPIb-mediated component of platelet adhesion was more pronounced in patients with premature CAD. This may indicate the possible role of excessive VWF-platelet interactions in the development of premature CAD.

Disconnect between COX-2 selective inhibition and cardiovascular risk in preclinical models

INTRODUCTION

Secondary pharmacology profiling is routinely applied in pharmaceutical drug discovery to investigate the pharmaceutical effects of a drug at molecular targets distinct from (off-target) the intended therapeutic molecular target (on-target). Data from a randomized, placebo-controlled clinical trial, the APPROVe (Adenomatous Polyp Prevention on VIOXX, rofecoxib) trial, raised significant concerns about COX-2 inhibition as a primary or secondary target, shaping the screening and decision-making processes of some pharmaceutical companies. COX-2 is often included in off-target screens due to cardiovascular (CV) safety concerns about secondary interactions with this target. Several potential mechanisms of COX-2-mediated myocardial infarctions have been considered including, effects on platelet stickiness/aggregation, vasal tone and blood pressure, and endothelial cell activation. In the present study, we focused on each of these mechanisms as potential effects of COX-2 inhibitors, to find evidence of mechanism using various in vitro and in vivo preclinical models.

METHODS

Compounds tested in the study, with a range of COX-2 selectivity, included rofecoxib, celecoxib, etodolac, and meloxicam. Compounds were screened for inhibition of COX-2 vs COX-1 enzymatic activity, ex vivo platelet aggregation (using whole blood from multiple species), ex vivo canine femoral vascular ring model, in vitro human endothelial cell activation (with and without COX-2 induction), and in vivo cardiovascular assessment (anesthetized dog).

RESULTS

The COX-2 binding assessment generally confirmed the COX-2 selectivity previously reported. COX-2 inhibitors did not have effects on platelet function (spontaneous aggregation or inhibition of aggregation), cardiovascular parameters (mean arterial pressure, heart rate, and left ventricular contractility), or endothelial cell activation. However, rofecoxib uniquely produced an endothelial mediated constriction response in canine femoral arteries.

CONCLUSION

Our data suggest that rofecoxib-related cardiovascular events in humans are not predicted by COX-2 potency or selectivity. In addition, the vascular ring model suggested possible adverse cardiovascular effects by COX-2 inhibitors, although these effects were not seen in vivo studies. These results may also suggest that COX-2 inhibition alone is not responsible for rofecoxib-mediated adverse cardiovascular outcomes.

Effect of Prostanoids on Human Platelet Function: An Overview

Prostanoids are bioactive lipid mediators and take part in many physiological and pathophysiological processes in practically every organ, tissue and cell, including the vascular, renal, gastrointestinal and reproductive systems. In this review, we focus on their influence on platelets, which are key elements in thrombosis and hemostasis. The function of platelets is influenced by mediators in the blood and the vascular wall. Activated platelets aggregate and release bioactive substances, thereby activating further neighbored platelets, which finally can lead to the formation of thrombi. Prostanoids regulate the function of blood platelets by both activating or inhibiting and so are involved in hemostasis. Each prostanoid has a unique activity profile and, thus, a specific profile of action. This article reviews the effects of the following prostanoids: prostaglandin-D₂ (PGD₂), prostaglandin-E₁, -E₂ and E₃ (PGE₁, PGE₂, PGE₃), prostaglandin F_2α (PGF_2α), prostacyclin (PGI₂) and thromboxane-A₂ (TXA₂) on platelet activation and aggregation via their respective receptors.

Shear-Dependent Platelet Aggregation: Mechanisms and Therapeutic Opportunities

Cardiovascular diseases (CVD) are the number one cause of morbidity and death worldwide. As estimated by the WHO, the global death rate from CVD is 31% wherein, a staggering 85% results from stroke and myocardial infarction. Platelets, one of the key components of thrombi, have been well-investigated over decades for their pivotal role in thrombus development in healthy as well as diseased blood vessels. In hemostasis, when a vascular injury occurs, circulating platelets are arrested at the site of damage, where they are activated and aggregate to form hemostatic thrombi, thus preventing further bleeding. However, in thrombosis, pathological activation of platelets occurs, leading to uncontrolled growth of a thrombus, which in turn can occlude the blood vessel or embolize, causing downstream ischemic events. The molecular processes causing pathological thrombus development are in large similar to the processes controlling physiological thrombus formation. The biggest challenge of anti-thrombotics and anti-platelet therapeutics has been to decouple the pathological platelet response from the physiological one. Currently, marketed anti-platelet drugs are associated with major bleeding complications for this exact reason; they are not effective in targeting pathological thrombi without interfering with normal hemostasis. Recent studies have emphasized the importance of shear forces generated from blood flow, that primarily drive platelet activation and aggregation in thrombosis. Local shear stresses in obstructed blood vessels can be higher by up to two orders of magnitude as compared to healthy vessels. Leveraging abnormal shear forces in the thrombus microenvironment may allow to differentiate between thrombosis and hemostasis and develop shear-selective anti-platelet therapies. In this review, we discuss the influence of shear forces on thrombosis and the underlying mechanisms of shear-induced platelet activation. Later, we summarize the therapeutic approaches to target shear-sensitive platelet activation and pathological thrombus growth, with a particular focus on the shear-sensitive protein von Willebrand Factor (VWF). Inhibition of shear-specific platelet aggregation and targeted drug delivery may prove to be much safer and efficacious approaches over current state-of-the-art antithrombotic drugs in the treatment of cardiovascular diseases.

Reversal of stress fibre formation by Nitric Oxide mediated RhoA inhibition leads to reduction in the height of preformed thrombi

Evidence has emerged to suggest that thrombi are dynamic structures with distinct areas of differing platelet activation and inhibition. We hypothesised that Nitric oxide (NO), a platelet inhibitor, can modulate the actin cytoskeleton reversing platelet spreading, and therefore reduce the capability of thrombi to withstand a high shear environment. Our data demonstrates that GSNO, DEANONOate, and a PKG-activating cGMP analogue reversed stress fibre formation and increased actin nodule formation in adherent platelets. This effect is sGC dependent and independent of ADP and thromboxanes. Stress fibre formation is a RhoA dependent process and NO induced RhoA inhibition, however, it did not phosphorylate RhoA at ser188 in spread platelets. Interestingly NO and PGI₂ synergise to reverse stress fibre formation at physiologically relevant concentrations. Analysis of high shear conditions indicated that platelets activated on fibrinogen, induced stress fibre formation, which was reversed by GSNO treatment. Furthermore, preformed thrombi on collagen post perfused with GSNO had a 30% reduction in thrombus height in comparison to the control. This study demonstrates that NO can reverse key platelet functions after their initial activation and identifies a novel mechanism for controlling excessive thrombosis.

The efficacy of parecoxib on systemic inflammatory response associated with cardiopulmonary bypass during cardiac surgery

AIMS

Cardiopulmonary bypass (CPB) during cardiac surgery is well known to be associated with the development of a systemic inflammatory response. The efficacy of parecoxib in attenuating this systemic inflammatory response is still unknown.

METHODS

Patients undergoing elective mitral valve replacement with CPB were assessed, enrolled and randomly allocated to receive parecoxib (80 mg) or placebo. Blood samples were collected in EDTA vials for measuring serum cytokine concentrations, troponin T, creatinekinase myocardial-brain isoenzyme CK-MB concentrations and white cell counts.

RESULTS

Compared with the control group, IL-6 and IL-8-values in the parecoxib group increased to a lesser extent, peaking at 2 h after the end of CPB (IL-6 31.8 pg ml⁻¹ ± 4.7 vs. 77.0 pg ml⁻¹ ± 14.1, 95% CI -47.6, -42.8, P < 0.001; IL-8 53.6 pg ml⁻¹ ± 12.6 vs. 105.7 pg ml⁻¹ ± 10.8, 95% CI -54.8, -49.4, P < 0.001). Peak concentrations of anti-inflammatory cytokine IL-10 occurred immediately after termination of CPB and were higher in the parecoxib group (115.7 pg ml⁻¹ ± 10.5 vs. 88.4 pg ml⁻¹ ± 12.3, 95% CI 24.7, 29.9, P < 0.001). Furthermore, the increase in neutrophil counts caused by CPB during cardiac surgery was inhibited by parecoxib. The increases in serum troponin T and CK-MB concentrations were also significantly attenuated by parecoxib in the early post-operative days. Peak serum concentrations of CK-MB in both groups occurred at 24 h post-CPB (17.4 μg l⁻¹ ± 5.2 vs. 26.9 μg l⁻¹ ± 6.9, 95% CI -10.9, -8.1, P < 0.001). Peak troponin T concentrations occurred at 6 h post-bypass (2 μg l⁻¹ ± 0.62 vs. 3.5 μg l⁻¹ ± 0.78, 95% CI -1.7, -1.3, P < 0.001).

CONCLUSION

Intra-operative parecoxib attenuated the systemic inflammatory response associated with CPB during cardiac surgery and lowered the biochemical markers of myocardial injury.

Effects of celecoxib on hematoma and edema volumes in primary intracerebral hemorrhage: a multicenter randomized controlled trial

BACKGROUND AND PURPOSE

We investigated the effect of celecoxib, a selective inhibitor of cyclo-oxygenase 2, in patients with intracerebral hemorrhage (ICH).

METHODS

We conducted a multicenter, randomized, controlled, and open with blinded end-point trial of 44 Korean patients 18 years or older with ICH within 24 h of onset. The intervention group (n = 20) received celecoxib (400 mg twice a day) for 14 days. The control group (n = 24) received the standard medical treatment for ICH. The primary end-point was the number of patients with a change in the volume of perihematomal edema (PHE) from the 1st to the 7th ± 1 day (cut-off value, 20%).

RESULTS

The time from onset to computed tomography scan slightly differed between groups (177 ± 160 min for control vs. 297 ± 305 min for the celecoxib group; P = 0.10). In the primary end-point analysis using cut-off values, there was a significant shift to reduced expansion of PHE in the celecoxib group (P = 0.005). With respect to the secondary end-points, there was also a significant shift to reduced expansion of ICH in the celecoxib group (P = 0.046). In addition, the expansion rate of PHE at follow-up tended to be higher in the control group than in the celecoxib group (90.6 ± 91.7% vs. 44.4 ± 64.9%; P = 0.058).

CONCLUSIONS

In our small, pilot trial, administration of celecoxib in the acute stage of ICH was associated with a smaller expansion of PHE than that observed in controls.

Lipoxygenase and Cyclooxygenase Pathways and Colorectal Cancer Prevention

Colorectal cancer is one of the commonest malignancies in both men and women. In spite of significant progress in screening and in surgical and therapeutic interventions, colorectal cancer (CRC) is still a major public health problem. Accumulating evidence suggests that targeting inflammatory pathways may provide protection against the development of CRC. Eicosanoids derived from the enzymes cyclooxygenase (COX) and lipoxygenase (LOX) may contribute to CRC carcinogenesis. Approaches for targeting COX-1 and COX-2 with traditional nonsteroidal anti-inflammatory agents or targeting COX-2 with specific inhibitors are highly successful at the preclinical and clinical levels; however, large-scale clinical applicability of these agents is limited owing to unwanted side effects. Emerging studies suggests that 5-LOX-derived leukotrienes may contribute to colon tumor development and risk of thrombotic events. Thus, developing drugs that target both 5-LOX and COX-2 may provide a safer strategy. In this review, we discuss evidence for the involvement of 5-LOX in colon tumor development and targeting 5-LOX and COX-2 with synthetic and naturally occurring agents for CRC prevention.

Migraine: possible role of shear-induced platelet aggregation with serotonin release

BACKGROUND

Migraine patients are at an increased risk for stroke, as well as other thromboembolic events. This warrants further study of the role of platelets in a proportion of migraine patients.

OBJECTIVE

To extend the "platelet hypothesis" using literature data and observations made in a rat model of shear stress-induced platelet aggregation. Such aggregation causes release of serotonin, leading to vasoconstriction during sufficiently strong aggregation and to long-lasting vasodilation when aggregation diminishes. This vasodilation also depends on nitric oxide and prostaglandin formation.

RESULTS

A role for platelet aggregation in a number of migraineurs is indicated by reports of an increased platelet activity during attacks and favorable effects of antiplatelet medication. We hypothesize that in those patients, a migraine attack with or without aura may both be caused by a rise in platelet-released plasma serotonin, albeit at different concentration. At high concentrations, serotonin may cause vasoconstriction and, consequently, the neuronal signs of aura, whereas at low concentrations, it may already stimulate perivascular pain fibers and cause vasodilation via local formation of nitric oxide, prostaglandins, and neuropeptides. Platelet aggregation may be unilaterally evoked by elevated shear stress in a stenotic cervico-cranial artery, by reversible vasoconstriction or by other cardiovascular abnormality, eg, a symptomatic patent foramen ovale. This most likely occurs when a migraine trigger has further enhanced platelet aggregability; literature shows that many triggers either stimulate platelets directly or reduce endogenous platelet antagonists like prostacyclin.

CONCLUSION

New strategies for migraine medication and risk reduction of stroke are suggested.

COX-2 Inhibition by Use of Rofecoxib or High Dose Aspirin Enhances ADP-Induced Platelet Aggregation in Fresh Blood

Aim:

Increased cardiovascular risk after use of selective or nonselective cyclooxygenase-2 (COX-2)-inhibitors might partly be caused by enhanced platelet aggregability. However, an effect of COX-2 inhibition on platelets has so far not been observed in humans.

Methods:

We tested in healthy volunteers the effect of COX-2-inhibition nearly in-vivo, i.e. immediately after and even during blood sampling.

Results:

Measurement within 2 minutes after venipuncture, but not 60 minutes later, showed that 50 mg of rofecoxib (n=12) or 500 (n=8) or 1000 (n=8) mg of aspirin increased ADP-induced platelet aggregation in a whole-blood aggregometer to, respectively, 152, 176 and 204 % of basal level (p<0.01). No significant differences in aggregability were observed after ingestion of 80 mg of aspirin (n=16), or placebo (n=8). Plasma 6-keto-PGF1α was decreased to 74 % after rofecoxib and to 76 and 70 % after 500 and 1000 mg of aspirin but did not change after low dose aspirin. Continuous photometrical measurement of aggregation in blood flowing from a cannulated vein revealed that high dose aspirin did not elicit aggregation by itself, but increased ADP-induced aggregation in proportion to the decrease in prostacyclin formation (r=0.68, p = 0.004). Since in these experiments thromboxane production was virtually absent, the enhanced aggregation after partial COX-2 inhibition was not caused by unopposed thromboxane formation.

Conclusions:

We conclude that both selective and nonselective COX-2 inhibition enhances ADP-induced platelet aggregation in humans. This effect can only be detected during or immediately after venipuncture, possibly because of the short half-life of prostacyclin.

Long-term outcome of adjunctive celecoxib treatment after paclitaxel-eluting stent implantation for the complex coronary lesions: two-year clinical follow-up of COREA-TAXUS trial

BACKGROUND

In the COREA-TAXUS trial ("Effect of Celecoxib On REstenosis after coronary Angioplasty with a TAXUS stent"), celecoxib reduced late luminal loss and adverse cardiac events at follow-up around 6 months. The objective of this study was to assess the long-term outcome of short-term adjunctive celecoxib treatment after paclitaxel-eluting stent implantation.

METHODS AND RESULTS

This is a 2-year clinical follow-up of the COREA-TAXUS trial, an open-label randomized controlled study. A total 274 patients were randomized to receive or not receive celecoxib (400 mg before the intervention and 200 mg twice daily for 6 months after the procedure), and 271 underwent successful paclitaxel-eluting stent implantation. All patients were given aspirin (100 mg daily indefinitely) and clopidogrel (75 mg daily for at least 6 months). Among the 271 patients, 267 (98.5%) completed the 2-year clinical follow-up. From the previous follow-up to 2 years, there was no difference in the rate of adverse cardiac events between the celecoxib and control groups (1.6% versus 4.3%, P=0.27). Thus, at 2 years, the rate of adverse cardiac events was consistently lower in the celecoxib group (6.9% versus 19.7%, P=0.002). A significant reduction in need for target lesion revascularization was observed (6.2% versus 18.2%, P=0.003). The efficacy benefit in the celecoxib group was not undermined by an increased risk for cardiac death or myocardial infarction at 2 years (1.5% versus 1.4%).

CONCLUSIONS

Six-month adjunctive celecoxib treatment after paclitaxel-eluting stent implantation was associated with durable long-term efficacy up to 2 years. However, the inconclusive evidence for the long-term safety of this treatment warrants caution.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00292721.

Acetylsalicylic acid enhances purinergic receptor-mediated outward currents in rat megakaryocytes

Purinergic receptor activation increases cytosolic Ca2+concentration in a fluctuating fashion, triggering oscillatory outward Ca2+-activated K+currents in rat megakaryocytes (MKs). Whole cell and nystatin-perforated patch-clamp techniques were used to analyze changes in ionic conductance in MK with acetylsalicylic acid (ASA), a cyclooxygenase-1 inhibitor and antithrombotic agent. MKs are a model for platelet reactivity, particularly in ASA treatment failure (ASA resistance). Freshly isolated MKs were incubated 30 min in the absence or presence of 1 mM ASA. Using a K+-rich internal solution, we recorded outward currents in response to 10 μM ATP, 10 μM ADP, and 5 μM 2-methyl-thio-ADP (2MeSADP) in the voltage-clamp mode. Agonist-induced currents decreased in amplitude over time, but this decline was attenuated by ASA in both continuous and repeated agonist challenge, indicating increased MK reactivity with ASA treatment. In separate experiments, heterologous desensitization was observed when MKs were stimulated with ADP after exposure to a thromboxane receptor agonist (U46619), indicating cross talk between thromboxane and purinergic pathways. Different cells, treated with ASA or MRS2179 (P2Y1 receptor antagonist), were stimulated with 2MeSADP. The dose-response curve was shifted to the left in both cases, suggesting increased MK reactivity. ASA also caused an increased interval between currents (delay). ASA attenuated desensitization of purinergic receptors and increased delay, again suggesting cross talk between purinergic and thromboxane pathways. These findings may be relevant to ASA resistance, because individual variations in sensitivity to the multiple effects of ASA on signaling pathways could result in insensitivity to its antiplatelet effects in some patients.

Inhibition of soluble epoxide hydrolase enhances the anti-inflammatory effects of aspirin and 5-lipoxygenase activation protein inhibitor in a murine model

Inflammation is a multi-staged process whose expansive phase is thought to be driven by acutely released arachidonic acid (AA) and its metabolites. Inhibition of cyclooxygenase (COX), lipoxygenase (LOX), or soluble epoxide hydrolase (sEH) is known to be anti-inflammatory. Inhibition of sEH stabilizes the cytochrome P450 (CYP450) products epoxyeicosatrienoic acids (EETs). Here we used a non-selective COX inhibitor aspirin, a 5-lipoxygenase activation protein (FLAP) inhibitor MK886, and a sEH inhibitor t-AUCB to selectively modulate the branches of AA metabolism in a lipopolysaccharide (LPS)-challenged murine model. We used metabolomic profiling to simultaneously monitor representative AA metabolites of each branch. In addition to the significant crosstalk among branches of the AA cascade during selective modulation of COX, LOX, or sEH, we demonstrated that co-administration of t-AUCB enhanced the anti-inflammatory effects of aspirin or MK886, which was evidenced by the observations that co-administration resulted in favorable eicosanoid profiles and better control of LPS-mediated hypotension as well as hepatic protein expression of COX-2 and 5-LOX. Targeted disruption of the sEH gene displayed a parallel profile to that produced by t-AUCB. These observations demonstrate a significant level of crosstalk among the three major branches of the AA cascade and that they are not simply parallel pathways. These data illustrate that inhibition of sEH by both pharmacological intervention and gene knockout enhances the anti-inflammatory effects of aspirin and MK886, suggesting the possibility of modulating multiple branches to achieve better therapeutic effects.

Cardiovascular safety of the cyclooxygenase-2 selective inhibitors parecoxib and valdecoxib in the postoperative setting: an analysis of integrated data

BACKGROUND

Studies of parecoxib, the inactive prodrug of the cyclooxygenase-2 selective inhibitor valdecoxib, and valdecoxib for postoperative pain relief in patients undergoing coronary artery bypass graft surgery revealed an increased risk of cardiovascular (CV) adverse events compared with placebo. We conducted this study to address whether parecoxib and valdecoxib increased CV risk in noncardiac surgery patients.

METHODS

A pooled post hoc analysis was conducted using 2 large datasets: 17 controlled trials of parecoxib for noncardiac studies and 32 studies, including the 17 noncardiac parecoxib studies plus 15 studies of valdecoxib. The 32-study dataset provided 95% power to detect a twofold increase in the incidence of CV adverse events assuming a placebo group incidence of 1% (estimated from previous study data), and 69% power to detect a twofold increase from a 0.5% incidence.

RESULTS

The incidence of total CV events for the 17 parecoxib studies was 0.44% (13 of 2966) in patients who received parecoxib and 0.37% (7 of 1915) in those receiving placebo (P > 0.20). In the analysis of 32 studies, the incidence of total CV events was 0.40% (21 of 5285) in the parecoxib/valdecoxib group compared with 0.50% (16 of 3226) in the placebo group (P > 0.20). No significant differences in the incidence of total or any individual CV event category were observed between the parecoxib or parecoxib/valdecoxib and placebo groups in the two analyses. When patients were stratified by number of baseline CV risk factors, no significant difference in CV events was detected in parecoxib/valdecoxib patients compared with placebo.

CONCLUSIONS

In the largest analysis of the CV risk of cyclooxygenase selective inhibitors or nonsteroidal antiinflammatory drugs for perioperative pain management, parecoxib and valdecoxib were not found to increase the risk of CV adverse events after noncardiac surgery.

Autologous interleukin-1 receptor antagonist improves function and symptoms in osteoarthritis when compared to placebo in a prospective randomized controlled trial

INTRODUCTION

Incubation of blood with CrSO(4)-coated glass beads stimulates the synthesis of anti-inflammatory cytokines, such as interleukin-1 receptor antagonist (IL-1ra), IL-4, IL-10, and IL-13. As IL-1beta is thought to play a key role in the development of osteoarthritis (OA), this product, also known as Orthokin, might be a viable treatment for symptomatic knee OA. The aim of the current study was to evaluate the efficacy of Orthokin for treatment of symptomatic knee OA in a randomized, multicentre, double-blind, placebo-controlled trial.

PATIENTS AND METHODS

One hundred and sixty-seven patients received six intra-articular injections either with Orthokin or physiological saline. The primary efficacy objective consisted of 30% superiority on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 3, 6, 9, and 12 months post-treatment. Additionally, the patients completed the visual analogue scale for pain, the Knee injury and Osteoarthritis Outcome Score (KOOS) and Knee Society Clinical Rating System.

RESULTS

Orthokin and placebo treatment resulted in similar improvements on the WOMAC (16.8% vs 16.5%, respectively; n.s.). Orthokin resulted in significantly more improvement for KOOS symptom (P = 0.002) and KOOS sport (P = 0.042) parameters as compared to placebo treatment. For most other outcome parameters, Orthokin-treated patients consistently showed higher improvement compared to placebo-treated patients, although none of these differences were statistically significant. Two serious adverse events were observed in the Orthokin group: one patient with repeated severe inflammatory reactions of the knee joint within hours after the injection and one patient with septic arthritis which was attributed to the injection procedure rather than the product.

CONCLUSION

The statistically significant improvement of KOOS symptom and sport parameters together with the consistently higher, though non-statistically significant, improvement of most other parameters demonstrates that Orthokin clearly induces a biological response different from placebo treatment and warrant future investigations into the possible chondroprotective effect of Orthokin. However, in the current study the primary efficacy objective was not met and, therefore, the use of Orthokin currently cannot yet be recommended for the treatment of OA.

Anti-inflammatory renoprotective effect of clopidogrel and irbesartan in chronic renal injury

Recent evidence suggests that platelet activation and angiotensin II may each contribute to glomerular inflammation and fibrosis. Clopidogrel inhibits platelet activation and may also reduce inflammation. This study investigated the anti-inflammatory and renoprotective effects of clopidogrel and irbesartan in the five-sixths nephrectomy rat model of chronic kidney disease. After 8 wk of treatment, 24-h proteinuria, serum creatinine, and histologic scores of glomerular sclerosis and tubulointerstitial damage were significantly lower in treated compared with untreated rats. Clopidogrel/irbesartan combination therapy had greater effects than either drug alone. Rats that underwent five-sixths nephrectomy had higher markers of platelet activation (plasma GMP-140 and renal cortical fibrin deposition) than sham-operated rats, and clopidogrel attenuated these effects. Clopidogrel and irbesartan similarly reduced the accumulation of ED-1-expressing macrophages in the cortical glomeruli and the interstitium. Combination therapy almost completely abolished macrophage infiltration and attenuated the expression of monocyte chemoattractant protein-1, intercellular adhesion molecule-1, TGF-beta(1), and connective tissue growth factor. In conclusion, combination treatment with clopidogrel and irbesartan, more so than either alone, decreases early renal injury induced by five-sixths nephrectomy by inhibiting renal inflammation.

Effect of celecoxib on restenosis after coronary angioplasty with a Taxus stent (COREA-TAXUS trial): an open-label randomised controlled study

BACKGROUND

In-vitro and animal experiments have shown that the cyclo-oxygenase 2 inhibitor celecoxib can reduce formation of neointima within stents. We aimed to test whether celecoxib has similar effects in a clinical setting.

METHODS

In a randomised two-centre trial, we enrolled 274 patients who had angina pectoris or a positive stress test and who had native coronary artery lesions for which implantation of paclitaxel-eluting stents was feasible. All patients were given aspirin (100 mg daily) and clopidogrel (75 mg daily). 136 patients were randomly assigned to receive celecoxib (400 mg before the intervention, and 200 mg twice daily for 6 months after the procedure). The primary endpoint was late luminal loss on quantitative coronary angiography at 6 months after the intervention. Secondary endpoints were cardiac death, non-fatal myocardial infarction, and revascularisation of the target lesion. Analysis was done on a modified intention-to-treat basis. This study is registered with ClinicalTrials.gov, number NCT00292721.

FINDINGS

At 6 months, mean in-stent late luminal loss was lower in the celecoxib group (0.49 mm, SD 0.47) than in the control group (0.75 mm, 0.60) (absolute difference 0.26 mm; 95% CI 0.12-0.40). Frequency of secondary outcomes at 6 months was also lower in the celecoxib group, mainly because of a reduced need for revascularisation of the target lesion.

INTERPRETATION

These data suggest that the adjunctive use of celecoxib for 6 months after stent implantation in patients with coronary artery disease is safe and can reduce the need for revascularisation of the target lesion.

The BC genotype of the VNTR polymorphism of platelet glycoprotein Ibalpha is overrepresented in patients with recurrent stroke regardless of aspirin therapy

BACKGROUND

The contribution of genetic factors to aspirin treatment failure (ATF) for secondary prevention is not settled in patients with ischemic stroke.

METHODS

We assessed the polymorphisms VNTR (A, B, C, D) of glycoprotein (GP) Ibalpha, 807C/T of GP Ia/IIa, and Pl(A1/A2) of GP IIb/IIIa, and the 5-year incidence of major recurrent events in 82 stroke patients with no major sources of cardioembolism (mean age 70, SD 9.0 years; female gender 23%). Using a structured interview, all participants confirmed good compliance with aspirin (100-300 mg/day) for secondary prevention. Demographics and atherothrombotic risk factors assessed included diabetes, hypertension, dyslipemia, smoking, and coronary heart disease.

RESULTS

Thirty-one stroke patients had one recurrent stroke or myocardial infarction within 33 (7-48) months of aspirin onset, while 51 patients demonstrated an uneventful clinical course. Female gender (p < 0.05), diabetes (p < 0.05), dyslipemia (p < 0.05), and the BC genotype of VNTR (25.8 vs. 7.8%, p < 0.05) were more prevalent in patients in whom aspirin failed to prevent clinical events than in those in whom it did not. The BC genotype of VNTR was the only factor that remained associated with ATF in an age-, sex-, and risk factor-adjusted logistic regression analysis (OR 9.6, 95% CI 1.5-61.0).

CONCLUSION

The BC genotype of the VNTR polymorphism of GP Ibalpha is an independent predictor of recurrent events in stroke patients treated with aspirin. This finding suggests that high shear-induced platelet activation mediated by GP Ibalpha and von Willebrand factor is an important contributor to ATF in the stroke population.

Update on the role of non-opioids for postoperative pain treatment

Non-opioids play an ever increasing role in the treatment of postoperative pain; either on their own for mild to moderate pain or in combination with other analgesic approaches, in particular opioids, as a component of multimodal analgesia. The analgesics paracetamol (acetaminophen) and dipyrone (metamizole) as well as compounds with an additional anti-inflammatory effect (non-selective non-steroidal anti-inflammatory drugs and selective cyclo-oxygenase-2 inhibitors) are used widely in the perioperative period. Paracetamol is gaining renewed interest in this setting due to its minimal adverse effects and recent availability in a parenteral preparation, but its benefits are insufficiently studied. Dipyrone continues to be used in many countries despite the ongoing debate on the incidence and relevance of its ability to cause agranulocytosis. Among the anti-inflammatory drugs, selective cyclo-oxygenase-2 inhibitors have the most supportive data for their beneficial effects as a component of multimodal analgesia and offer benefits with regard to their adverse effect profile.