Association between plasma lipoprotein(a) and endothelial dysfunction in normocholesterolemic and non-diabetic patients with angiographically normal coronary arteries

Multimodal CRISPR perturbations of GWAS loci associated with coronary artery disease in vascular endothelial cells

Genome-wide association studies have identified >250 genetic variants associated with coronary artery disease (CAD), but the causal variants, genes and molecular mechanisms remain unknown at most loci. We performed pooled CRISPR screens to test the impact of sequences at or near CAD-associated genetic variants on vascular endothelial cell functions. Using CRISPR knockout, inhibition and activation, we targeted 1998 variants at 83 CAD loci to assess their effect on three adhesion proteins (E-selectin, ICAM1, VCAM1) and three key endothelial functions (nitric oxide and reactive oxygen species production, calcium signalling). At a false discovery rate ≤10%, we identified significant CRISPR perturbations near 42 variants located within 26 CAD loci. We used base editing to validate a putative causal variant in the promoter of the FES gene. Although a few of the loci include genes previously characterized in endothelial cells (e.g. AIDA, ARHGEF26, ADAMTS7), most are implicated in endothelial dysfunction for the first time. Detailed characterization of one of these new loci implicated the RNA helicase DHX38 in vascular endothelial cell senescence. While promising, our results also highlighted several limitations in using CRISPR perturbations to functionally dissect GWAS loci, including an unknown false negative rate and potential off-target effects.

Relation of High Lipoprotein (a) Concentrations to Platelet Reactivity in Individuals with and Without Coronary Artery Disease

INTRODUCTION

Lipoprotein (a) [Lp(a)] is a risk factor for coronary artery disease (CAD). To the best of our knowledge, this is the first study addressing the relationship between Lp(a) and platelet reactivity in primary and secondary prevention.

METHODS

Lp(a) was evaluated in 396 individuals with (82.3%) and without (17.7%) obstructive CAD. The population was divided into two groups according to Lp(a) concentrations with a cutoff value of 50 mg/dL. The primary objective was to evaluate the association between Lp(a) and adenosine diphosphate (ADP)-induced platelet reactivity using the VerifyNow™ P2Y₁₂ assay. Platelet reactivity was also induced by arachidonic acid and collagen-epinephrine (C-EPI) and assessed by Multiplate™, platelet function analyzer™ 100 (PFA-100), and light transmission aggregometry (LTA) assays. Secondary objectives included the assessment of the primary endpoint in individuals with or without CAD.

RESULTS

Overall, 294 (74.2%) individuals had Lp(a) < 50 mg/dL [median (IQR) 13.2 (5.8-27.9) mg/dL] and 102 (25.8%) had Lp(a) ≥ 50 mg/dL [82.5 (67.6-114.5) mg/dL], P < 0.001. Univariate analysis in the entire population revealed no differences in ADP-induced platelet reactivity between individuals with Lp(a) ≥ 50 mg/dL (249.4 ± 43.8 PRU) versus Lp(a) < 50 mg/dL (243.1 ± 52.2 PRU), P = 0.277. Similar findings were present in individuals with (P = 0.228) and without (P = 0.669) CAD, and regardless of the agonist used or method of analysis (all P > 0.05). Finally, multivariable analysis did not show a significant association between ADP-induced platelet reactivity and Lp(a) ≥ 50 mg/dL [adjusted OR = 1.00 [(95% CI 0.99-1.01), P = 0.590].

CONCLUSION

In individuals with or without CAD, Lp(a) ≥ 50 mg/dL was not associated with higher platelet reactivity.

Assessment of traditional and non-traditional risk factors for premature atherosclerosis in children with juvenile dermatomyositis and pediatric controls

BACKGROUND

Children with juvenile dermatomyositis (JDM), the most common inflammatory myopathy of childhood, may be at increased risk of premature atherosclerosis given a host of traditional and non-traditional risk factors. The primary aim of this study was to determine the underlying frequency of premature atherosclerosis in children with JDM compared to pediatric controls using flow-mediated dilation as a measure of endothelial function.

METHODS

Children and adolescents with and without JDM were evaluated for traditional atherosclerotic risk factors and assessment of endothelial function, using Endothelial Pulse Amplitude Testing (Endo-PAT).

RESULTS

In this study, 75% of pediatric controls were of Black or Hispanic descent (compared to 55% in the JDM group) and 70% were found to live in a household with a medium income less than $50,000/year (compared to 45% in the JDM group). Among traditional atherogenic risk factors, lipoprotein A appeared to be different between controls and JDM patients (66 nmol/L and 16.5 nmol/L, respectively). Using a reactive hyperemia index (RHI) < 1.67 as evidence of endothelial dysfunction, 75% of controls were defined as having endothelial dysfunction compared to 50% in JDM group. When controlled for lipoprotein A as an atherogenic confounder, JDM patients were found to have a 41% increase in RHI, thus indicating less endothelial dysfunction compared to controls.

CONCLUSIONS

In this study, we have shown that atherogenic risk factors are present in the pediatric population and may be associated with endothelial dysfunction, even at very young ages. Despite increasing concerns that children with rheumatologic disorders may be at increased risk of developing premature atherosclerosis, traditional and sociodemographic features may play a greater role in the ultimate development of cardiovascular disease.

Impact of serum lipoprotein(a) on endothelium-dependent coronary vasomotor response assessed by intracoronary acetylcholine provocation

BACKGROUND

Lipoprotein(a) [Lp(a)] is an independent risk factor for atherosclerotic vascular disease. However, there are limited data regarding the impact of Lp(a) levels on the incidence and severity of endothelium-dependent coronary vasomotor response.

PATIENTS AND METHODS

A total of 2416 patients without significant coronary artery lesion (<50% stenosis) by coronary angiography and underwent acetylcholine (ACh) provocation test were enrolled and categorized according to their serum Lp(a) level into four quartile groups: less than 6.70, 6.70-13.30, 13.30-26.27, and more than 26.27 mg/dl. The aim of this study is to estimate the incidence and severity of endothelium-dependent positive ACh provocation test in each group; moreover, to access the incidence of major adverse cardiovascular events, the composite of total death, myocardial infarction, and de novo percutaneous coronary intervention were compared between the four groups up to 5 years.

RESULTS

The group with higher Lp(a) had a higher incidence of coronary heart disease, myocardial infarction, and peripheral arterial disease history. However, there was no difference among the four groups as regards the incidence of positive ACh provocation test, spasm severity, spasm extent, and location. However, at up to 5 years of clinical follow-up, the higher-Lp(a) group showed higher total death, de novo percutaneous coronary intervention, recurrent angina, and total major adverse cardiovascular events compared with the lower-Lp(a) groups.

CONCLUSION

In our study, there was no relationship between the elevated Lp(a) level and the vasospastic response to the intracoronary ACh provocation test; however, higher Lp(a) levels were associated with poor clinical outcomes up to 5 years.

Chronic exercise reduces platelet activation in hypertension: upregulation of the L-arginine-nitric oxide pathway

Nitric oxide (NO) inhibits platelet function and plays a key role in the regulation of cardiovascular homeostasis. Essential hypertension is characterized by an increased risk of thrombus formation, and by an inhibition of intraplatelet NO bioactivity. We have previously shown that membrane transport of L-arginine is a rate-limiting step for platelet-derived NO synthesis. This study examined the effects of exercise on the platelet L-arginine-NO pathway and aggregation and systemic inflammation markers in 13 sedentary hypertensive patients subjected to 60 min of training activity (exercise group), predominantly aerobic, three times a week for a period of 12 weeks. Six sedentary hypertensive patients participated in the control group. After 12 weeks, L-arginine transport was significantly increased and associated with increased platelet NO synthase activity and cGMP levels and reduced platelet aggregation. Moreover, exercise training reduced plasma concentrations of fibrinogen and C-reactive protein and blood pressure. The control group did not change their previous intraplatelet L-arginine-NO results and systemic inflammatory markers levels. Thus, exercise training reduces inflammatory responses, restores NO synthesis in platelets and thereby contributes to the beneficial effects of exercise in hypertension. The present study adds exercise as a new tool to reduce morbidity and mortality associated with platelet activation in hypertension.

Changes in haemocoagulation in healthy volunteers after a 1-hour thrombotripsy using a diagnostic 2–4 MHz transcranial probe

INTRODUCTION

The aim was to monitor the changes in haemocoagulation parameters in healthy volunteers after a thrombotripsy with 1-hour transcranial Doppler monitoring using a 2-4 MHz probe.

MATERIALS AND METHODS

About 10 healthy volunteers underwent a 1-hour thrombotripsy of the middle cerebral artery (MCA), thrombotripsy of the radial artery and a standard 20-min neurosonologic examination (NSE) in 2-week intervals. Platelet count, aPTT, prothrombin time, fibrinogen, D-dimers, tPA, FDP, alpha-2-antiplasmin (AP), plasminogen, PAI-1 antigen, time of euglobulin clot lysis (ECL), homocysteine, and lipoprotein (a) were examined before, at the end and 24 h after a thrombotripsy. All adverse events were monitored.

RESULTS

After a thrombotripsy of the MCA, PAI-1 antigen, tPA antigen, fibrinogen and AP activity were significantly decreased by a mean of 32, 23, 7, and 4% respectively (P < 0.05 in all cases). After a thrombotripsy of the RA, there was a significant decrease in tPA antigen alone by an average of 14% (P < 0.05). Standard NSE did not affect any of the measured factors.

CONCLUSIONS

Thrombotripsy with 1-hour TCD monitoring using a 2-4 MHz diagnostic probe may affect the fibrinolytic system in humans.

Linking inflammation and atherogenesis: Soluble markers identified for the detection of risk factors and for early risk assessment

Increasing evidence has shown that atherogenesis is not only caused by hypercholesterolemia. Several risk factors including abdominal obesity, dyslipidemia, hyperglycemia, bacterial and viral infection, hyperhomocysteinemia have been identified recently, all mediated through inflammation, which can lead to atherosclerosis. Several events have also been identified to be involved in the overall inflammation reaction in the blood vessel which include endothelium dysfunction, expression of adhesion molecules, recruitment of leukocytes to the injured endothelium, migration of monocytes to the arterial intima, and transformation of monocytes to macrophages. In order to facilitate the assessment of early risk for atherogenesis we have made an effort in this review to identify soluble markers that will allow the detection of these risk factors and the identification of associated inflammation events. Since early risks for atherogenesis are largely preventable with dietary modification and lifestyle changes, capable of detecting early risks by monitoring soluble risk markers is conceivably important for asymptomatic individuals to avoid serious or fatal consequences of atherosclerosis. These soluble markers should also be useful for monitoring the effectiveness of intervention and for the identification of therapeutic targets.

Relationship between serum lipoprotein(a) concentrations and coronary vasomotion in coronary spastic angina

BACKGROUND

Elevated lipoprotein(a) (Lp(a)) concentrations are reported to impair endothelium-dependent vasodilatation of the epicardial coronary artery. However, the effects on vasomotor abnormalities in coronary spastic angina (CSA) have not been thoroughly investigated.

METHODS AND RESULTS

In the present study 80 sites of spasm (spastic sites) without significant organic stenosis (% diameter stenosis <50%) were assessed in 80 patients with CSA diagnosed by intracoronary ergonovine (EM) test. Spastic sites were divided into 2 groups: Group 1 included 30 sites provoked by the full dose (=50 microg) of EM, and Group 2 included 50 sites provoked with less than 50 microg (34.7+/-8.2 microg). Control subjects (n=22) did not show coronary spasm with the EM test. Serum Lp(a) concentrations were measured in all patients. Group 2 had a significantly greater basal coronary artery tone in the spastic sites than Group 1 (p<0.001). Lp(a) level in Group 2 was significantly higher compared with both the control group and Group 1 (p<0.05 by analysis of variance). Multivariate analysis confirmed that only serum Lp(a) concentration was associated with low-dose EM spasm provocation.

CONCLUSIONS

Serum Lp(a) concentration could be a marker for high disease activity in CSA.

Use of atropine in patients with recent myocardial infarction during exercise myocardial perfusion study

BACKGROUND

Patients with recent myocardial infarction frequently require a myocardial perfusion study for risk stratification. However a conclusive study cannot be accomplished in many due to non-attainment of target heart rate.

AIM OF THE STUDY

To evaluate the effect of pre-stress administration of atropine in exercise performance of patients with recent myocardial infarction.

MATERIAL AND METHODS

Study included 43 test and 43 control patients and were matched for their age, sex, status of pretest exercise tolerance, area of infarction and for interval between infarction and stress thallium test. Atropine (0.01 mg/kg) was administered intravenously 3 min prior to treadmill stress in all the 43 test patients and no atropine was administered to control patients.

RESULTS

Target heart rate was attained in 95.3% patients receiving atropine compared to in 67.4% of control patients. There was no significant difference between mean ages (p>0.33), basal BP (p>0.47), peak BP (p>0.18) of both groups. There was significant difference between the increment in exercise-induced heart rate (p<0.004), peak heart rate (p<0.001) and double product (p<0.001) attained between both groups. No significant adverse effect was noted in patients who received atropine.

CONCLUSION

Pre-stress administration of atropine in patients with recent myocardial infarction is safe and results in a significantly better exercise performance, which might be useful in decreasing the number of equivocal myocardial perfusion studies.

Relation between serum lipoprotein (a) and residual lesion stenosis of coronary artery after myocardial Infarction without reperfusion therapy

Lipoprotein (a) (Lp(a)) is an independent risk factor for myocardial infarction (MI). It may also inhibit the fibrinolysis system, and Lp (a) affects the natural course of MI and the results of thrombolytic therapy. The purpose of this study was to investigate the influence of Lp (a) on the residual lesion stenosis of the infarction-related arteries (residual stenosis) in acute MI patients in whom reperfusion therapy was not performed. We studied 129 MI patients not given reperfusion therapy who underwent coronary angiography in the chronic stage. Morning fasting blood was collected and Lp (a), blood sugar, total cholesterol (TC), triglycerides (TG), and hemoglobin A1c (HbA1c) were measured. Residual stenosis was compared between the low Lp(a) group (< 30 mg/dL) and the high Lp(a) group (> or = 30 mg/dL). It was severe in the high Lp(a) group (85.0 +/- 24.9% vs 94.5 +/- 15.5%, P = 0.0044). We also compared residual stenosis and TIMI classification between younger and older, non-DM and DM, non-HT and HT, low-TC (< 220 mg/dL) and high-TC (> or = 220 mg/dL), low-TG (< 150 mg/dL) and high-TG (> or = 150 mg/dL), and low-Lp (a) and high-Lp (a) patients. Only the serum Lp (a) level affected the residual stenosis and TIMI classification (P < 0.05).

CONCLUSION

These findings suggest that elevated Lp (a) levels inhibit fibrinolysis.

Endocrine causes of impotence (nondiabetes)

The endocrine system has a major role in erections in normal men and it can also be a cause of significant morbidity. The relationship between serum testosterone measurement and erectile function is complex. Androgen treatment should certainly be considered in patients without prostate cancer but with a clinical picture that suggests a relevant contribution of hypogonadism to the ED. Other, nondiabetic, endocrine abnormalities may need to be considered in the management or the patient with ED.