Relationship of coagulation and fibrinolytic variables with arterial structure and function in Africans

The association of PAI-1 with 24 h blood pressure in young healthy adults is influenced by smoking and alcohol use: The African-PREDICT study

BACKGROUND AND AIMS

The association between plasminogen activator inhibitor-1 (PAI-1) and blood pressure is well established, but it is debatable whether raised PAI-1 levels precede or result from raised blood pressure. Furthermore, it is unclear whether this association already exists in the absence of overt hypertension and to what degree it is influenced by health behaviours. Our aim was to investigate the association of 24 h blood pressure with PAI-1 activity (PAI-1_act) in a young, healthy cohort, and to assess the influence of alcohol consumption and smoking on these associations.

METHODS AND RESULTS

Healthy black and white men and women (aged 20-30 years, n = 1156) were cross-sectionally analysed. Statistical analysis was performed first split by ethnicity and sex and then by alcohol consumption and smoking. Regression analyses adjusted for age revealed positive associations of 24 h blood pressure with PAI-1_act in most groups (p < 0.05). In multivariate-adjusted analyses, significance was lost in all groups except black men, who also had higher monocyte chemoattractant protein-1 (MCP-1) and von Willebrand factor antigen (vWF_ag) compared to white men (both p < 0.001). Analyses in black men, split by self-reported alcohol use and smoking, revealed 24 h blood pressure-PAI-1_act associations only in alcohol users (24 h SBP [B = 4.22, p < 0.001], DBP [B = 2.04, p = 0.015] and PP [B = 2.18, p = 0.013]) and smokers (24 h SBP [B = 6.10, p < 0.001] and PP [B = 4.33, p = 0.001]).

CONCLUSION

Our findings support a positive association between 24 h blood pressure and PAI-1, particularly in individuals with higher MCP-1 and vWF_ag levels. Furthermore, smoking and alcohol consumption play an important role in modifying the association between blood pressure and PAI-1.

Plasminogen activator inhibitor-1 activity and the 4G/5G polymorphism are prospectively associated with blood pressure and hypertension status

OBJECTIVES

Plasminogen activator inhibitor-1 (PAI-1) has consistently shown positive associations with blood pressure (BP). Whether elevations in PAI-1 levels precede or result from raised BP is still under debate and data on prospective studies are limited. Hence, we investigated the prospective associations of PAI-1 and the 4G/5G polymorphism with brachial and central BP and pulse pressure (PP) over a 10-year period.

METHODS

Black South Africans aged 30 years and older were included. Baseline data collection commenced in 2005 (n = 2010) with follow-up data collection in 2010 (n = 1288) and 2015 (n = 926). Plasma PAI-1 activity (PAI-1act), 4G/5G polymorphism genotyping, waist circumference and BP measurements were performed and analysed using sequential regression and mixed models.

RESULTS

In multivariable adjusted analyses, PAI-1act and the 4G/4G (vs. the 5G/5G) genotype increased the odds of developing hypertension in the total group [1.04 (1.01; 1.08) and 1.82 (1.07; 3.12) respectively]. Furthermore, PAI-1act was prospectively associated with brachial SBP (r = 0.0815) and PP (r = 0.0832) in the total group, and with central PP in women (r = 0.1125; all P < 0.05). Addition of waist circumference to the models either decreased or nullified the contribution of PAI-1act to BP and hypertension development.

CONCLUSION

PAI-1act and the 4G/4G (vs. the 5G/5G) genotype increased the odds of developing hypertension. Furthermore, PAI-1act associated prospectively with both brachial and central BP. These associations were mediated in part by central adiposity. The study supports the hypothesis that PAI-1 also contributes to hypertension development rather than solely being a consequence thereof.

The Effect of Exenatide on Cardiovascular Risk Markers in Women With Polycystic Ovary Syndrome

Background: Polycystic ovary syndrome (PCOS) is associated with an adverse cardiovascular risk profile including a prothrombotic state. Exenatide has been shown to be effective at improving insulin sensitivity and weight loss in PCOS; therefore this study was undertaken to assess its effects on weight, endothelial function, inflammatory markers, and fibrin structure/function in overweight/obese women with PCOS. Methods: Thirty overweight/obese anovulatory women with all 3 Rotterdam criteria received exenatide 5 mcg bd for 4 weeks then 10 mcg bd for 12 weeks. The primary outcome was change in weight; secondary outcomes were changes in endothelial function [Reactive Hyperemia-Peripheral Arterial Tonometry (RH-PAT)], serum endothelial markers (ICAM-1, VCAM-1, E-selectin, and P-selectin), change in inflammation (hsCRP), and alteration in clot structure and function [maximum absorbance (MA), and time from full clot formation to 50% lysis (LT)]. Results: Twenty patients completed the study. Exenatide reduced weight 111.8 ± 4.8 to 108.6 ± 4.6 kg p = 0.003. Serum endothelial markers changed with a reduction in ICAM-1 (247.2 ± 12.9 to 231.3 ± 11.5 ng/ml p = 0.02), p-selectin (101.1 ± 8.2 to 87.4 ± 6.6 ng/ml p = 0.01), and e-selectin (38.5 ± 3.3 to 33.6 ± 2.6 ng/ml p = 0.03), without an overt change in endothelial function. Inflammation improved (CRP; 8.5 ± 1.4 to 5.6 ± 0.8 mmol/L p = 0.001), there was a reduction in clot function (LT; 2,987 ± 494 to 1,926 ± 321 s p = 0.02) but not clot structure. Conclusion: Exenatide caused a 3% reduction in weight, improved serum markers of endothelial function, inflammation, and clot function reflecting an improvement in cardiovascular risk indices in these women with PCOS. This suggests exenatide could be an effective treatment for obese women with PCOS. Clinical Trial Registration: ISRCTN81902209.

Gamma prime (γ') fibrinogen and carotid intima-media thickness: the Atherosclerosis Risk in Communities study

: We assessed if γ' fibrinogen, an isoform of fibrinogen, is independently associated with subclinical atherosclerosis beyond total fibrinogen in black and white men and women participating in the Atherosclerosis Risk in Communities study. Fasting γ' fibrinogen was measured in 6847 Atherosclerosis Risk in Communities participants, ages 51-70 years, in 1993-1995. Carotid intima-media far wall thickness (CIMT) was measured by B-mode ultrasonography at the common, internal and bifurcation carotids. The association of γ' fibrinogen tertiles with overall and segment-specific mean CIMT was assessed with linear regression, controlling for fibrinogen as well as cardiovascular risk factors, including high-sensitivity C-reactive protein and D-dimer. γ' Fibrinogen values ranged from 8.0 to 80.3 mg/dl and were positively related to age, female sex, black race, smoking, BMI, lipids and SBP. Crude γ' fibrinogen was directly associated with all CIMT measures except for the internal carotid, but explained less than 1% of the variance in the associations. Adjustment for total fibrinogen eliminated these associations, and total fibrinogen remained an independent predictor of CIMT without explaining additional variance. Adjustment for potential confounding variables did not alter the observed associations, which did not differ by race or sex. In these cross-sectional data, γ' fibrinogen was not independently associated with CIMT when controlling for total fibrinogen. γ' Fibrinogen and total fibrinogen together explained a very small proportion of the variance in CIMT, regardless of the carotid site. If γ' fibrinogen adds to total fibrinogen's ability to predict subclinical atherosclerosis, it may be in younger populations.

Endosulfan activates the extrinsic coagulation pathway by inducing endothelial cell injury in rats

Endosulfan, a persistent organic pollutant, is widely used in agriculture as a pesticide. The aim of the present study was to evaluate the blood toxicity of different doses of endosulfan in Wistar rats. The experimental sample was composed of four groups, a control group that did not receive endosulfan and three endosulfan-exposed groups that respectively received 1, 5, or 10 mg/kg/day (doses below LD50), of endosulfan for 21 days. The results showed that endosulfan significantly decreased the prothrombin time (PT) and upregulated the activated coagulation factors VIIa, Xa, and XIIIa; thrombin-antithrombin complex (TAT); and P-selectin. Plasma levels of tissue factor (TF) and malondialdehyde (MDA) were increased in the endosulfan groups. The activated partial thromboplastin time (APTT) and the level of activated coagulation factor IXa showed no obvious changes. Immunohistochemical results showed increased expression of von Willebrand factor (vWF) and the inflammatory cytokine interleukin (IL)-1β in the groups exposed to endosulfan. The pathology and electron microscopy results showed impaired vascular tissue accompanied by the exfoliation of endothelial cells and mitochondrial damage in the endosulfan-exposed groups. In summary, our results suggest that endosulfan damages endothelial cells via oxidative stress and the inflammatory response, leading to the release of TF and vWF into the blood. The TF and vWF in the blood may activate extrinsic coagulation factors and platelets, thus triggering the extrinsic coagulation pathway. There were no obvious effects on the intrinsic coagulation pathway.

The association of clot lysis time with total obesity is partly independent from the association of PAI-1 with central obesity in African adults

INTRODUCTION

Preliminary evidence indicates that the association of fibrinolytic potential, measured as clot lysis time (CLT), with body composition may differ from that of plasminogen activator inhibitor type-1 (PAI-1). We therefore investigated the association between fibrinolytic markers (plasminogen activator inhibitor type-1 activity (PAI-1act) and CLT) and body composition using detailed body composition analyses.

MATERIALS AND METHODS

Data from 1288 Africans were cross-sectionally analyzed. Body composition analysis included BMI, waist circumference (WC); waist to height ratio (WHtR), skinfolds and body fat percentage measured with air-displacement plethysmography and bioelectrical impedance analysis.

RESULTS

PAI-1act and CLT were significantly higher in women than in men, despite adjustment for differences in body composition. PAI-1act and CLT showed similar linear positive relationships with body composition (BMI, WC, WHtR, skinfolds) in men. In women CLT also showed a linear relationship with body composition, while PAI-1act levels plateaued at higher BMI and did not differ across skinfold categories. PAI-1act showed stronger correlations with body composition markers in men than it did in women, while no sex differences existed for CLT. PAI-1act associated more strongly with central obesity, while CLT associated with total body fat.

CONCLUSIONS

Observed differences may be related to differences in adipose tissue type, distribution and sequence of accumulation between sexes. PAI-1act is strongly influenced by accumulation of visceral adipose tissue, whereas CLT is associated with obesity independent of type and sequence of body fat accumulation in this African adult study population.