Fibrinolysis inhibitors in plaque stability: a morphological association of PAI-1 and TAFI in advanced carotid plaque.

Essentials Fibrinolysis inhibitors are localized in advanced atheroma by immunohistology of endarterectomies. Neovascular endothelium/neocapillaries show thrombin-activatable fibrinolysis inhibitor (TAFI). Macrophage areas show free plasminogen activator inhibitor (PAI-1), notably in the vulnerable part. Free PAI-1 and TAFI stabilize active plaque area by inhibition of fibrinolysis and inflammation. SUMMARY: Background Fibrinolysis plays an important role in destabilization of atherosclerotic plaques and is tightly regulated by specific inhibitors. Objective The fibrinolysis inhibitors plasminogen activator inhibitor type-1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI) were quantified and described in the morphological context of advanced carotid plaques American Heart Association VI-VIII to elucidate their role in plaque stability. Methods Immunohistochemistry in serial sections along the longitudinal axis of endarterectomies from patients with symptomatic carotid stenosis (n = 19) were studied using an antibody specific for free PAI-1 (I205), an antibody with high affinity for TAFI/TAFIa (CP17) and established antibodies for smooth muscle cells (α-actin), endothelial cells (von Willebrand factor [VWF]), macrophages (CD68) and platelets (CD42). Results PAI-1 and TAFI show a specific distribution in these advanced plaques with a maximum corresponding to the internal carotid artery (ICA). Free PAI-1 was mainly detected in macrophages and in intravascular thrombi, and TAFI in endothelial cells (ECs) but also macrophages. The one-way ANOVA analysis with Bonferroni's correction showed a significant increase of macrophages and ECs, TAFI and PAI-1 in areas with high neovascularization in endarterectomy sections corresponding to ICA. High Spearman factors for TAFI, PAI-1 and VWF indicate neovascularization as the main source of plasma proteins, transported by platelets into the atheroma (PAI-1) or expressed by ECs (TAFI). CD68 was highly associated with VWF, PAI-1 and especially TAFI, underlining the role of macrophages in fibrinolytic activity and inflammation. Conclusion The abundance of free PAI-1 and TAFI in the plaque may inhibit plasmin generation and thereby counteract plaque destabilization by fibrinolysis, cell migration and inflammation.

Risk of Recurrent Stroke in Patients with Symptomatic Mild (20-49% NASCET) Carotid Artery Stenosis.

OBJECTIVE: The objective of this study was to evaluate the risk of recurrent ischaemic stroke in patients with ultrasound assessed symptomatic mild carotid artery stenosis (20-49% NASCET) treated solely with modern medical treatment. METHOD: This was a retrospective, observational register cohort study. Three groups of patients were recruited from a database of all carotid Doppler ultrasound examinations performed in the Gothenburg region between 2004 and 2009. Patients with symptomatic mild carotid artery stenosis (n = 162) were compared with patients with asymptomatic carotid artery stenosis (n = 301) of equal degree and a group of patients with surgically (CEA) treated symptomatic moderate or severe carotid artery stenosis (n = 220). Kaplan-Meier estimates and Cox proportional hazard models were used to compare the primary outcome (ipsilateral ischaemic stroke) between groups. RESULTS: After a 3 year follow up, the cumulative incidence of recurrent ipsilateral stroke in patients with symptomatic mild carotid artery stenosis was 7.4%. Patients with symptomatic mild carotid artery stenosis had a substantially increased risk of recurrent ipsilateral stroke compared with asymptomatic patients with equal degree of stenosis (HR 5.5. 95% CI 1.8-17.1; p = .003) as also compared with patients with CEA treated symptomatic moderate or severe stenosis (HR 7.8. 95% CI 1.62-37.8; p = .011). CONCLUSIONS: The present study on patients with symptomatic mild carotid artery stenosis, as determined by Doppler ultrasound, shows that there is still a substantial risk of recurrent stroke in this group.

Risk of early recurrent stroke in symptomatic carotid stenosis.

OBJECTIVES: The risk of recurrent stroke in patients with symptomatic carotid artery stenosis is highest in the first weeks after a transient ischemic attack (TIA) or minor stroke and can be reduced with carotid endarterectomy (CEA). The optimal timing of CEA remains a controversial issue since very urgent CEA is associated with an increased procedural risk. The aim of this study was to determine the risk of very early recurrent stroke in a population with symptomatic high grade carotid stenosis. METHODS: Data were analyzed on all patients with ocular TIA, TIA, or minor stroke with >70% carotid stenosis as assessed by carotid ultrasound at Sahlgrenska University Hospital during the periods 2004-2006 and 2010-2012. The two time periods were chosen to minimize selection bias and to analyze changes over time. The risk of recurrent stroke within 30 days of the referring event was assessed. RESULTS: 397 patients with symptomatic carotid stenosis were identified. The risk of recurrent stroke in the total cohort was 2.0% (CI 95% 0.6-3.4) by day 2, 4.0% (CI 95% 2.0-5.9) by day 7, and 7.5% (CI 95% 4.4-10.6) by day 30. There was no significant difference between the two time periods. Patients with minor stroke had a significantly higher risk of recurrent stroke than patients with TIA or ocular TIA as the referring event. CONCLUSIONS: The data suggest that the early risk of recurrent stroke in symptomatic significant carotid stenosis is not as high as some earlier studies have shown. The risk is similar to several studies in which a modern medical treatment regime could be assumed.

Identification of vascularised carotid plaques using a standardised and reproducible technique to measure ultrasound contrast uptake.

OBJECTIVES: Contrast-enhanced ultrasonography (CEUS) has been used to assess the vascularisation of carotid plaques. Our aim was to develop and validate a standardised semi-automated method for CEUS examination of plaques, and test if the technique could be used to identify vulnerable plaques. METHODS: Study participants were a mixed population of symptomatic and asymptomatic subjects, selected if they had a plaque with height >2.5 mm and <10% acoustic shadowing. Participants received a bolus of ultrasound contrast agent and a 90-s cine-loop was captured. A Contrast Quantification Program (CQP) was developed and trained to identify extent of contrast uptake after motion correction and application of a noise reduction algorithm. The technique was validated by comparing CQP values with visual assessment of contrast uptake. CQP values were also compared with plaque echogenicity and history of clinical events. RESULTS: CQP values correlated with a visual, 5-scale classification of contrast uptake by two blinded, experienced sonographers. Repeated contrast injections showed high reproducibility. Participants with a history of ipsilateral stroke/TIA had significantly higher CQP values than asymptomatic participants. CONCLUSION: We present a reproducible, semi-automatic method to identify vascularisation of carotid plaques, which could be used in prospective studies to determine the clinical value of plaque vascularisation.

The lipocalins retinol-binding protein-4, lipocalin-2 and lipocalin-type prostaglandin D2-synthase correlate with markers of inflammatory activity, alcohol intake and blood lipids, but not with insulin sensitivity in metabolically healthy 58-year-old Swedish men.

The lipocalins retinol-binding protein (RBP)-4, lipocalin-2 and lipocalin-type prostaglandin D-synthase (L-PGDS) have been suggested to mediate obesity-associated insulin resistance and other metabolic co-morbidities. The role of lipocalins is however controversial and it is unclear whether they have a physiological role in regulation of insulin sensitivity and metabolic function in clinically healthy humans. Therefore, we examined the correlations between serum levels of RBP-4, L-PGDS and lipocalin-2 and insulin sensitivity and other metabolic parameters in non-diabetic subjects selected to display variations in insulin sensitivity. 100 clinically healthy 58-year-old Swedish men were selected by stratified sampling among 818 screened subjects to represent quintiles of varying degrees of insulin sensitivity. Insulin sensitivity was measured by the euglycaemic hyperinsulinaemic clamp method. Serum levels of lipocalins and cytokines were determined using antibody-based techniques. Serum lipids were measured by standardized laboratory methods. None of the measured lipocalins showed any correlations with insulin sensitivity. However, we found that lipocalin-2 and L-PGDS were correlated with each other, but not with RBP-4. Lipocalin-2 and L-PGDS were positively correlated with soluble TNF- receptors 1 and 2 and negatively with alcohol consumption and serum HDL. Further, lipocalin-2 was correlated with interleukin-6 whereas RBP-4 was negatively correlated with TNF-α. □These results suggest that RBP-4, lipocalin-2 and L-PGDS do not regulate insulin sensitivity in healthy men. Rather the expression levels of lipocalin-2 and L-PGDS, but not RBP-4, seemed to reflect inflammatory activity and were inversely correlated with alcohol intake and serum HDL levels.