Prothrombotic effect of Rofecoxib in a murine venous thrombosis model

Blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice

Obese and diabetic states in humans are associated with an increased incidence of thrombotic diseases caused by various coagulation abnormalities. Genetically obese ob/ob mice produce metabolic abnormalities similar to those associated with type 2 diabetes. However, little is known about their coagulation features or sex differences. The present study aimed to determine the effects of obese and diabetic complications on blood coagulation and vascular diseases by exploring correlations between blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice. Plasma levels of plasminogen activator inhibitor 1 (PAI-1) were significantly increased, whereas those that of platelet factor-4 (PF-4) was slightly, but significantly increased in male and female ob/ob mice compared with lean counterparts. Prothrombin time (PT) was significantly shortened in female ob/ob mice and activated partial thrombin time (APTT) significantly differed between male and female ob/ob mice. Plasma levels of antithrombin (AT) were significantly increased in male and female ob/ob mice. None of the other coagulation and fibrinolytic factors examined significantly differed between ob/ob mice and lean counterparts. On the contrary, factors such as body weight and cholesterol levels significantly differed between ob/ob and lean mice, whereas glucose, fructosamine and insulin levels significantly differed only in one sex of each strain. These results provided fundamental information about blood coagulation and metabolic features for exploring the function of altered blood coagulation states in ob/ob mice.

Myeloid cell microsomal prostaglandin E synthase-1 fosters atherogenesis in mice

Microsomal prostaglandin E synthase-1 (mPGES-1) in myeloid and vascular cells differentially regulates the response to vascular injury, reflecting distinct effects of mPGES-1-derived PGE2 in these cell types on discrete cellular components of the vasculature. The cell selective roles of mPGES-1 in atherogenesis are unknown. Mice lacking mPGES-1 conditionally in myeloid cells (Mac-mPGES-1-KOs), vascular smooth muscle cells (VSMC-mPGES-1-KOs), or endothelial cells (EC-mPGES-1-KOs) were crossed into hyperlipidemic low-density lipoprotein receptor-deficient animals. En face aortic lesion analysis revealed markedly reduced atherogenesis in Mac-mPGES-1-KOs, which was concomitant with a reduction in oxidative stress, reflective of reduced macrophage infiltration, less lesional expression of inducible nitric oxide synthase (iNOS), and lower aortic expression of NADPH oxidases and proinflammatory cytokines. Reduced oxidative stress was reflected systemically by a decline in urinary 8,12-iso-iPF2α-VI. In contrast to exaggeration of the response to vascular injury, deletion of mPGES-1 in VSMCs, ECs, or both had no detectable phenotypic impact on atherogenesis. Macrophage foam cell formation and cholesterol efflux, together with plasma cholesterol and triglycerides, were unchanged as a function of genotype. In conclusion, myeloid cell mPGES-1 promotes atherogenesis in hyperlipidemic mice, coincident with iNOS-mediated oxidative stress. By contrast, mPGES-1 in vascular cells does not detectably influence atherogenesis in mice. This strengthens the therapeutic rationale for targeting macrophage mPGES-1 in inflammatory cardiovascular diseases.

Cyclooxygenase-2-derived prostacyclin regulates arterial thrombus formation by suppressing tissue factor in a sirtuin-1-dependent-manner

BACKGROUND

Selective inhibitors of cyclooxygenase (COX)-2 increase the risk of myocardial infarction and thrombotic events, but the responsible mechanisms are not fully understood.

METHODS AND RESULTS

We found that ferric chloride-induced arterial thrombus formation was significantly greater in COX-2 knockout compared with wild-type mice. Cross-transfusion experiments excluded the likelihood that COX-2 knockout platelets, despite enhanced aggregation responses to collagen and thrombin, are responsible for increased arterial thrombus formation in COX-2 knockout mice. Importantly, we observed that COX-2 deletion decreased prostacyclin synthase and production and peroxisome proliferator-activated receptor- and sirtuin-1 (SIRT1) expression, with consequent increased upregulation of tissue factor (TF), the primary initiator of blood coagulation. Treatment of wild-type mice with a prostacyclin receptor antagonist or a peroxisome proliferator-activated receptor-δ antagonist, which predisposes to arterial thrombosis, decreased SIRT1 expression and increased TF activity. Conversely, exogenous prostacyclin or peroxisome proliferator-activated receptor-δ agonist completely reversed the thrombotic phenotype in COX-2 knockout mice, restoring normal SIRT1 levels and reducing TF activity. Furthermore, inhibition of SIRT1 increased TF expression and activity and promoted generation of occlusive thrombi in wild-type mice, whereas SIRT1 activation was sufficient to decrease abnormal TF activity and prothrombotic status in COX-2 knockout mice.

CONCLUSIONS

Modulation of SIRT1 and hence TF by prostacyclin/peroxisome proliferator-activated receptor-δ pathways not only represents a new mechanism in controlling arterial thrombus formation but also might be a useful target for therapeutic intervention in the atherothrombotic complications associated with COX-2 inhibitors.

Non-steroidal anti-inflammatory drug use and risk of venous thromboembolism

BACKGROUND

The association between the use of non-selective non-steroidal anti-inflammatory drugs (NSAIDs) or cyclooxygenase-2-selective inhibitors (COX2Is) and the risk of venous thromboembolism (VTE) remains unclear.

OBJECTIVES

 To examine this association.

PATIENTS/METHODS

 We conducted a population-based case-control study in northern Denmark (population of 1.7 million). Using the National Patient Registry, we identified patients with a first hospital VTE diagnosis during 1999-2006 (n = 8368) and their comorbidities. For each case, we selected 10 controls (n = 82, 218) matched by age and sex. From the prescription database, we ascertained the use of NSAIDs at the time of diagnosis (current use) or before (recent use), and comedications. Current use was further classified as new use (first-ever prescription redemption within 60 days before diagnosis date) or long-term use. We used odds ratios from a logistic regression model to estimate incidence rate ratios (IRRs) with 95% confidence intervals (CIs).

RESULTS

 As compared with no use, the adjusted IRR associating current non-selective NSAID use with VTE was 2.51 (95% CI 2.29-2.76), and that for current COX2I use was 2.19 (95% CI 1.99-2.41). Recent users had substantially smaller increases than current users. The adjusted IRRs among long-term users were 2.06 for non-selective NSAIDs (95% CI 1.85-2.29) and 1.92 for COX2Is (95% CI 1.72-2.15). Similarly increased risks were found for unprovoked VTE (occurrence in the absence of pregnancy, cancer, major trauma, fracture or surgery within 3 months preceding the VTE), deep vein thrombosis, pulmonary embolism, and individual NSAIDs.

CONCLUSIONS

The use of non-selective NSAIDs or COX2Is was associated with a two-fold or more increased risk of VTE.