Aspirin reduces the prothrombotic activity of C-reactive protein.

AIM: C-reactive protein (CRP) is a risk marker and a potential modulator of vascular disease. Previous studies support a prothrombotic activity of CRP, with impaired thromboregulation. The present study examined the antithrombotic effect of aspirin in mice transgenic for human CRP (CRPtg mice). Mechanistic investigations further elucidated the effect of CRP on prostanoid metabolism in vivo and in vitro. METHODS AND RESULTS: Administration of aspirin (30 mg kg(-1) day(-1)) to CRPtg mice slowed the accelerated thrombosis after photochemical injury to the carotid (99 +/- 32 vs. 45 +/- 24 min and 75 +/- 23 vs. 82 +/- 26 min in wild-type mice vs. CRPtg mice, without and following aspirin treatment, respectively). Vascular injury modulated the expression of key pathways in prostanoid metabolism differently in CRPtg mice and wild-type mice. Suppression of cyclo-oxygenase 2 (COX-2)-derived metabolism with suppression of prostaglandin I2 (PGI2) synthase and PGI2 metabolism was recorded in the injured artery with increased thromboxane receptor expression. Aspirin therapy reduced the difference in PGI2 biosynthesis between CRPtg mice and wild-type mice. In vitro studies in human-derived cells further supported these findings. Incubation of human umbilical vein endothelial cells (HUVECs) with human recombinant CRP (5 microg mL(-1)) suppressed PGI2 synthase expression and significantly increased thromboxane receptor levels. Incubation of smooth muscle cells with CRP did not affect prostanoid expression. CONCLUSIONS: CRP modulates prostanoid metabolism to favor vascular occlusion. Elevated CRP levels might predispose to the cardiovascular hazard conferred by selective COX-2 inhibitors, and the risk mediated by CRP may be limited by aspirin.

Innate immunity has a dual effect on vascular healing: suppression and aggravation of neointimal formation and remodeling post-endotoxin challenge.

BACKGROUND: Inflammation is important to vascular repair following injury, modulating neointimal proliferation and remodeling. Previously, we have shown that a low-intensity inflammatory response aggravates neointimal formation following balloon and stent injury. The present study examined whether modulation of the extent and timing of nonspecific inflammation mediates the local vascular response in an additive unidirectional or rather a bidirectional fashion. METHODS AND RESULTS: Rabbits subjected to denudation and balloon injury of the iliac artery were treated with low (1 microg/kg) or high (100 microg/kg) doses of bacterial endotoxin (LPS) immediately after injury, or with early high-dose LPS administered 3 days prior to injury (preconditioning). Neointimal formation at 28 days was significantly increased in the low-dose group (0.537+/-0.059 mm(2)) as compared with controls (0.3+/-0.03 mm(2)). High-dose LPS did not significantly affect neointimal formation while early high dose significantly reduced neointima (0.296+/-0.033 and 0.194+/-0.025 mm(2), respectively, n=12-14/group). Arterial wall and systemically circulating interleukin-1 beta levels, and monocyte CD14 activation correlated with neointimal formation. Vascular remodeling was accelerated in animals treated with low- or high-dose LPS while not affected in the preconditioned group. Remodeling index inversely correlated with arterial matrix metalloproteinase-2 levels 6 days after injury. CONCLUSIONS: The extent and timing of nonspecific inflammation that is concurrent with vascular injury can determine different and opposite vascular repair patterns.