Our results indicate that PAR2 deficiency is associated with attenuation of atherosclerosis and may reduce lesion progression by blunting - and-induced monocyte infiltration.

Abdominal aortic aneurysm (AAA) is associated with high morbidity and mortality and is an established cause of unbalanced hemostasis. A number of hemostatic biomarkers have been associated with AAA; however, the utility of hemostatic biomarkers in AAA diagnosis and prognosis is unclear. The aim of the present study was to characterize the potential prognostic value of D-dimer and markers of altered hemostasis in a large cohort of patients with AAAs characterized by either fast or slow aneurysm growth (frequency matched for baseline diameter) and subaneurysmal dilations. We measured plasma concentrations of thrombin-antithrombin (TAT) complex, platelet factor 4 (PF4), and D-dimer in 352 patients with either fast-growing AAAs (>2 mm/y), slow-growing AAAs (<2 mm/y), subaneurysmal aortic dilations, or nonaneurysmal aortas. Plasma D-dimer and TAT were significantly elevated in both AAA and subaneurysmal dilation patients compared with controls. Individuals with D-dimer levels ≥500 ng/mL had 3.09 times the odds of subaneurysms, 6.23 times the odds of slow-growing AAAs, and 7.19 times the odds of fast-growing AAAs than individuals with D-dimer level <500 ng/mL. However, no differences in D-dimer concentration were noted between fast- and slow-growing aneurysms. Plasma D-dimer and TAT were strong independent predictors of AAA growth rate with multivariate analysis revealing a 500-ng/mL increase in D-dimer or 1-µg/mL increase in TAT led to additional 0.21-mm and 0.24-mm changes in aortic diameter per year, respectively. Rising levels of plasma TAT, in addition to D-dimer, may predict disease progression and aneurysm growth in patients with AAA or subaneurysmal dilation.

BackgroundCardiovascular disease is the leading cause of morbidity and mortality in patients with end‐stage renal disease. The accumulation of uremic solutes in this patient population is associated with endothelial dysfunction and accelerated cardiovascular disease. In this study, we examined the impact of the uremic milieu on the endothelial transcription factor, Krüppel‐like factor 2 (KLF2), a key regulator of endothelial function and activation.Methods and ResultsUsing serum from uremic pigs with chronic renal insufficiency, our results show that KLF2 expression is suppressed by the uremic milieu and individual uremic solutes in vitro. Specifically, KLF2 expression is significantly decreased in human umbilical vein endothelial cells after treatment with uremic porcine serum or carboxymethyllysine‐modified albumin, an advanced glycation end product (AGE) known to induce endothelial dysfunction. AGE‐mediated suppression of KLF2 is dependent on activation of the receptor for AGE, as measured by small interfering RNA knockdown of the receptor for AGE. Furthermore, KLF2 suppression promotes endothelial dysfunction, because adenoviral overexpression of KLF2 inhibits reactive oxygen species production and leukocyte adhesion in human umbilical vein endothelial cells. In addition, the application of hemodynamic shear stress, prolonged serum dialysis, or treatment with the receptor for AGE antagonist azeliragon (TTP488) is sufficient to prevent KLF2 suppression in vitro. To decipher the mechanism by which uremic AGEs suppress KLF2 expression, we assessed the role of the receptor for AGE in activation of nuclear factor‐κB signaling, a hallmark of endothelial cell activation. Using a constitutively active form of IκBα, we show that translocation of p65 to the nucleus is necessary for KLF2 suppression after treatment with uremic AGEs.ConclusionsThese data identify KLF2 suppression as a consequence of the uremic milieu, which may exacerbate endothelial dysfunction and resultant cardiovascular disease.

Acute tefillin use improves vascular function while chronic tefillin use is associated with an anti-inflammatory RIPC-like phenotype.

Objective: Protease-activated receptor 2 (PAR-2)-dependent signaling results in augmented inflammation and has been implicated in the pathogenesis of several autoimmune conditions. While PAR-2 protein is present in coronary atherosclerotic lesions, the relevance of this finding has not been investigated in experimental models. The objective of this study was to determine the effects of PAR-2 on the development of atherosclerosis. Methods and Results: Relative expression of PAR-2 is increased in human coronary artery (21 fold) and mouse aortic arch (16 fold) atheromas versus control coronary and aortic arch arteries, respectively (P = 0.001). To determine the effect of PAR-2 deficiency on atherosclerosis, male low density lipoprotein receptor deficient ( Ldlr -/- ) mice (8-12 weeks old) that were Par-2 +/+ or Par-2 -/- were fed a fat and cholesterol-enriched diet for 12 (n = 10 each group) or 24 weeks (n = 5 each group). PAR-2 deficiency attenuated atherosclerosis in the aortic sinus and aortic root with no effects on total plasma cholesterol concentrations or lipoprotein distributions after 12 (P = 0.000433) and 24 (P = 0.037) weeks. These reductions were attributable to both hematopoietic and non-hematopoietic-derived PAR-2 from analysis of bone marrow experiments (n = 15 for each of 4 chimeric groups; P < 0.05). Mechanistic studies using ex vivo macrophages show that activation of PAR-2 results in augmented foam cell formation and apoptosis with treatment of oxidized low-density lipoprotein in conjunction with decreased expression of the nuclear receptor LXR-alpha and several cholesterol transporters. In addition, PAR-2 activation of ex-vivo cultured vascular smooth muscle cells (VSMCs) augments their transition to a macrophage-like state (after cholesterol treatment) via upregulation of human antigen R (HuR) and resultant stabilization of the transcription factor Krüppel-like factor 4 (KLF4). Conclusion: Our results indicate PAR-2 deficiency significantly attenuates the initiation (12 weeks) and reduces the progression (24 weeks) of atherosclerosis potentially via regulation of both lipid efflux from macrophages and the phenotypic modulation of VSMCs.