Host genetic variants associated with COVID-19 reconsidered in a Slovak cohort

We present the results of an association study involving hospitalized coronavirus disease 2019 (COVID-19) patients with a clinical background during the 3rd pandemic wave of COVID-19 in Slovakia. Seventeen single nucleotide variants (SNVs) in the eleven most relevant genes, according to the COVID-19 Host Genetics Initiative, were investigated. Our study confirms the validity of the influence of LZTFL1 and 2'-5'-oligoadenylate synthetase (OAS)1/OAS3 genetic variants on the severity of COVID-19. For two LZTFL1 SNVs in complete linkage disequilibrium, rs17713054 and rs73064425, the odds ratios of baseline allelic associations and logistic regressions (LR) adjusted for age and sex ranged in the four tested designs from 2.04 to 2.41 and from 2.05 to 3.98, respectively. The OAS1/OAS3 haplotype 'gttg' carrying a functional allele G of splice-acceptor variant rs10774671 manifested its protective function in the Delta pandemic wave. Significant baseline allelic associations of two DPP9 variants in all tested designs and two IFNAR2 variants in the Omicron pandemic wave were not confirmed by adjusted LR. Nevertheless, adjusted LR showed significant associations of NOTCH4 rs3131294 and TYK2 rs2304256 variants with severity of COVID-19. Hospitalized patients' reported comorbidities were not correlated with genetic variants, except for obesity, smoking (IFNAR2), and hypertension (NOTCH4). The results of our study suggest that host genetic variations have an impact on the severity and duration of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Considering the differences in allelic associations between pandemic waves, they support the hypothesis that every new SARS-CoV-2 variant may modify the host immune response by reconfiguring involved pathways.

Platelet Adhesion Mediated by von Willebrand Factor at High Shear Rates Is Associated with Premature Coronary Artery Disease

This study investigated von Willebrand factor (VWF)-mediated platelet adhesion at high shear rates in patients with premature coronary artery disease (CAD). The study included 84 patients with stable premature CAD and 64 patients without CAD. Whole blood samples were perfused through a microfluidic cell over a collagen-coated surface at a shear rate of 1300 s^-1. Measurements were performed before and after the inhibition of VWF-specific platelet GPIb receptors with an anti-GPIb monoclonal antibody (mAb). Platelet adhesion decreased by 77.0% (55.9; 84.7) in patients with premature CAD and by 29.6% (0.0; 59.7) in control patients after the inhibition of VWF-platelet interaction with anti-GPIb mAb (p < 0.001). After adjusting for traditional risk factors, the odds ratio for premature CAD per 1% decrease in GPIb-mediated platelet adhesion was 1.03 (95% CI, 1.02-1.05; p < 0.001). The optimal cut-off level value of GPIb-mediated platelet adhesion was 62.8%, with 70.2% sensitivity and 81.2% specificity for CAD. The plasma levels of VWF or antiplatelet therapy did not affect the GPIb-mediated component of platelet adhesion. Thus, the GPIb-mediated component of platelet adhesion was more pronounced in patients with premature CAD. This may indicate the possible role of excessive VWF-platelet interactions in the development of premature CAD.

Von Willebrand factor in diagnostics and treatment of cardiovascular disease: Recent advances and prospects

Von Willebrand factor (VWF) is a large multimeric glycoprotein involved in hemostasis. It is essential for platelet adhesion to the subendothelium of the damaged endothelial layer at high shear rates. Such shear rates occur in small-diameter arteries, especially at stenotic sites. Moreover, VWF carries coagulation factor VIII and protects it from proteolysis in the bloodstream. Deficiency or dysfunction of VWF predisposes to bleeding. In contrast, an increase in the concentration of high molecular weight multimers (HMWM) of VWF is closely associated with arterial thrombotic events. Severe aortic stenosis (AS) or hypertrophic obstructive cardiomyopathy (HOCM) can deplete HMWM of VWF and lead to cryptogenic, gastrointestinal, subcutaneous, and mucosal bleeding. Considering that VWF facilitates primary hemostasis and a local inflammatory response at high shear rates, its dysfunction may contribute to the development of coronary artery disease (CAD) and its complications. However, current diagnostic methods do not allow for an in-depth analysis of this contribution. The development of novel diagnostic techniques, primarily microfluidic, is underway. Such methods can provide physiologically relevant assessments of VWF function at high shear rates; however, they have not been introduced into clinical practice. The development and use of agents targeting VWF interaction with the vessel wall and/or platelets may be reasonable in prevention of CAD and its complications, given the prominent role of VWF in arterial thrombosis.

The monomeric C-reactive protein level is associated with the increase in carotid plaque number in patients with subclinical carotid atherosclerosis

The high-sensitivity C-reactive protein (hsCRP) assay measures the level of the pentameric form of CRP in blood. Currently, there are no available assays measuring the level of the monomeric form of CRP (mCRP), produced at sites of local inflammation. We developed an assay measuring the mCRP level in blood plasma with functional beads for flow cytometry. The assay was used to measure the mCRP level in 80 middle-aged individuals with initially moderate cardiovascular SCORE risk. By the time of the mCRP measurement, the patients have been followed up for subclinical carotid atherosclerosis progression for 7 years. Ultrasound markers of subclinical atherosclerosis, which included plaque number (PN) and total plaque height (PH), were measured at baseline and at the 7th-year follow-up survey. Inflammatory biomarkers, including mCRP, hsCRP, inteleukin-6 (IL-6) and von Willebrand factor (VWF) level, were measured at the 7th-year follow-up survey. The median level of mCRP was 5.2 (3.3; 7.1) μg/L, hsCRP 1.05 (0.7; 2.1) mg/L, IL-6 0.0 (0.0; 2.8) pg/mL, VWF 106 (77; 151) IU/dL. In the patients with the mCRP level below median vs. the patients with the median mCRP level or higher, change from baseline in PN was 0.0 (0.0; 1.0) vs. 1.0 (1.0; 2.0) and PH 0.22 (−0.24; 1.91) mm vs. 1.97 (1.14; 3.14) mm, respectively (p < 0.05). The adjusted odds ratio for the formation of new carotid atherosclerotic plaques was 4.7 (95% CI 1.7; 13.2) for the patients with the median mCRP level or higher. The higher mCRP level is associated with the more pronounced increase in PN and PH in patients with normal level of traditional inflammatory biomarkers and initially moderate cardiovascular SCORE risk.

Peak Responses during Exercise Treadmill Testing using Individualized Ramp Protocol and Modified Bruce Protocol in Elderly Patients

BACKGROUND

Exercise capacity is well known to be an important prognostic factor in patients with cardiovascular disease and among healthy persons.

AIM

To determine if there are any differences between the peak exercise response during exercise treadmill testing with the individualized ramp protocol and the modified Bruce protocol in elderly patients.

MATERIALS AND METHODS

The study included 40 patients (both male and female), aged 70 years and older, who had not had a baseline history of the confirmed coronary artery disease or heart failure diagnoses. All patients underwent exercise treadmill testing using modified Bruce protocol and individualized ramp protocol for 2 consecutive days. Peak heart rate, peak systolic and diastolic blood pressure, peak pressure-rate double product, exercise duration, and peak metabolic equivalents were recorded in both tests. Perceived level of exertion was evaluated using the Borg 10-point scale.

RESULTS

The average duration of exercise was longer for the ramp protocol than for the modified Bruce protocol. When the modified Bruce protocol was used, patients achieved a lower workload than they did in using the ramp protocol. The rating of perceived exertion using the revised Borg scale (0 to 10) was 5.6±1.4 for the ramp protocol and 8.7±1.4 for the modified Bruce protocol, which indicates that the patients found the ramp protocol easier.

CONCLUSION

In elderly patients the individualized ramp treadmill protocol allows to achieve the optimal test duration with higher degrees of workload and greater patient comfort during the test more often than does the modified Bruce protocol.

P721Shear stress induced unfolding of von willebrand factor may be involved in the premature development of myocardial infarction

Background

Normally, von Willebrand factor (vWF) becomes highly reactive with platelets upon unfolding into a fibrillar conformation at critical shear rate (more than 5000 s–1), that may occur in stenotic arteries. At shear rates below critical value (1200–1300 s–1), which occur in intact coronary arteries, normally there is no conformational rearrangement of vWF. Pathologic unfolding of vWF at shear rates below critical value may increase a risk of the development of coronary thrombosis. There is little information on the role of shear stress induced conformational rearrangement of vWF in the development of myocardial infarction in young individuals.

Purpose

To investigate vWF-dependent platelet adhesion of patients with premature myocardial infarction at shear rates below critical value (1200–1300 s–1).

Methods

Using a microfluidic system, we measured platelet adhesion to a fibrinogen-coated optical surface at shear rates of 1200–1300 s–1 during 10 minutes. We assessed platelet-rich plasma of 8 male persons 40–52 years old, who had previous myocardial infarction at the age of 34–39. The control group comprised 6 healthy male volunteers 30–55 years old. We compared the intensity of scattered laser light measured in volts (V) at 10th minute. To study vWF-dependent platelet adhesion, we blocked GPIb receptor with monoclonal antibody to inhibit platelet interaction with vWF. To compare the intensity of vWF-dependent platelet adhesion with normally occurring adhesion to fibrinogen, we blocked GPIIb/IIIa receptor with monoclonal antibody.

Results

The inhibition of GPIb vWF-receptor decreased platelet adhesion to fibrinogen surface at shear rates of 1200–1300 s–1 by 17.8±4.7% in healthy volunteers and by 92±2.8% in persons with premature myocardial infarction (p<0.05). Inhibition of GPIIb/IIIa receptor decreased platelet adhesion by 91.5±3.8% in healthy volunteers and by 97.3±3.2% in persons with premature myocardial infarction.

Conclusion

Pathologic unfolding of vWF at shear rates below critical value may be involved in the development of premature myocardial infarction.

Acknowledgement/Funding

This work was supported by the grant of the Russian Science Foundation (project #16-15-10098)

Novel Biomarkers for Coronary Restenosis Occurrence After Drug-Eluting Stent Implantation in Patients With Diabetes Having Stable Coronary Artery Disease

The purpose of the study was to assess whether the occurrence of restenosis is associated with CD45+ platelet count and neutrophil to lymphocyte ratio in patients with type 2 diabetes mellitus (DM) after drug-eluting stent (DES) implantation for stable coronary artery disease (CAD). The study comprised 126 patients, including 55 patients with type 2 DM and stable CAD who underwent elective coronary artery stenting with DES and follow-up angiography within 6 to 12 months. Blood samples were collected from each patient on the morning of the coronary angiography procedure. The variables related to in-stent restenosis were selected by logistic regression analysis. The logistic regression analysis showed that 2 inflammatory factors, CD45+ platelet count (odds ratio [OR] = 4.51, 95% confidence interval [CI]: 1.50-13.50, P = .007) and neutrophil to lymphocyte ratio (OR = 3.09, 95% CI: 1.05-9.10, P = .04), were significantly associated with the risk of in-stent restenosis after stenting with DES in patients with stable CAD and type 2 DM. A receiver operator characteristic curve analysis indicated that the area under the curve was 0.83% (0.05%; P < .001), which showed that the logistic model had good predictive accuracy (based on CD45+ platelet count and neutrophil to lymphocyte ratio) for the risk of in-stent restenosis development in DES in patients with CAD and type 2 DM. Two novel biomarkers of restenosis, CD45+ platelet count and neutrophil to lymphocyte ratio, may be effectively used to predict in-stent restenosis after DES implantation in patients with CAD and type 2 DM.

Blood level of CD45+ platelets and development of restenosis after drug-eluting stent implantation in patients with stable coronary artery disease

OBJECTIVE

The aim of this study was to assess CD45-positive platelets (CD45+ platelets) involvement in restenosis development after drug-eluting stent (DES) implantation in patients with stable coronary artery disease (CAD).

METHODS

The study comprised 126 male and female patients with stable angina pectoris, who underwent elective coronary stenting with DES and follow-up angiography within 6-12 months. The patients were assigned to the group with restenosis (n = 53) or group without restenosis (n = 73) according to the follow-up angiograms. In both groups we compared the level in blood of CD45+ platelets, the clinical, laboratory and angiographic variables, which may affect the development of restenosis. We have also constructed a logit regression model for prognosis of restenosis occurrence after DES implantation.

RESULTS

The blood count of CD45+ platelets was higher in patients with restenosis than in patients without: 0.82 % (0.58; 1.12) vs. 0.34 % (0.20; 0.68), p < 0.001, data are expressed as median (lower quartile; upper quartile). By binary comparisons of more than 35 different clinical, laboratory and angiographic variables we identified 8 significant risk factors for the development of stent restenosis after DES. In order to define the risk of the development of restenosis, we have built a logit regression model. The resulting logit regression equation included the level of CD45+ platelets, the neutrophil to lymphocyte ratio (NLR), small diameter arteries stenting and the number of simultaneously implanted stents in one patient. Receiver operating characteristic (ROC) curve analysis has demonstrated the high prognostic value of the resulting logit regression equation with an area under the curve (AUC) of 0.91 % (p < 0.001).

CONCLUSIONS

The acquired data indicate the presence of a close relationship between circulating CD45+ platelets and restenosis development after DES implantation in patients with stable CAD.

Impact of platelet phenotype on myocardial infarction

In acute myocardial infarction patients the injured vascular wall triggers thrombus formation in the damage site. Fibrin fibers and blood cellular elements are the major components of thrombus formed in acute occlusion of coronary arteries. It has been established that the initial thrombus is primarily composed of activated platelets rapidly stabilized by fibrin fibers. This review highlights the role of platelet membrane phenotype in pathophysiology of myocardial infarction. Here, we regard platelet phenotype as quantitative and qualitative parameters of the plasma membrane outer surface, which are crucial for platelet participation in blood coagulation, development of local inflammation and tissue repair.

Plasma urokinase antigen and C-reactive protein predict angina recurrence after coronary angioplasty

This study evaluates the predictive value of several biochemical indices of the coagulation-fibrinolysis system, platelet function, and inflammatory state for angina recurrence after successful percutaneous transluminal coronary angioplasty (PTCA). We measured preprocedural and follow-up plasma levels of C-reactive protein (CRP), fibrinogen, and urokinase plasminogen activator antigen (uPA), plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator activity, and adenosine diphosphate-induced platelet aggregation in 53 patients with chronic stable angina who underwent successful elective PTCA of single hemodynamically significant lesions in coronary arteries. All patients were followed up for 12 months after PTCA. The Cox proportional hazards model was used to assess the association of variables with angina recurrence rate. At the end of the follow-up, 16 patients had angina recurrence. Among 36 clinical, biochemical, and angiographic variables, the duration of stable angina more than 12 months before PTCA (χ (2) = 5.73; P = 0.02, hazard ratio (HR) 3.7, 95 % confidence interval (CI) 1.26-10.6), high baseline levels of CRP (>7 mg/l) (χ (2) = 8.34; P = 0.004, HR 2.9, 95 % CI 1.4-5.9), uPA antigen baseline (>1 ng/ml) (χ (2) = 17.11; P = 0.0001, HR 11.5, 95 % CI 3.6-36.7) and 48 h after PTCA (χ (2) = 15.73; P = 0.0001, HR 8.8, 95 % CI 3.01-25.96), baseline PAI-1 activity (>18 IU/ml) (χ (2) = 9.37; P = 0.002, HR 7.6, 95 % CI 2.07-27.84) were significant predictors of recurrent angina by univariate analyses. According to stepwise multivariate analyses, only the levels of plasma uPA antigen and serum CRP were shown to be significant independent predictors of angina recurrence (multivariate uPA χ (2) = 8.22, P = 0.004, HR 6.2, 95 % CI 1.78-21.67; CRP χ (2) = 4.09, P = 0.04, HR 1.9, 95 % CI 1.02-3.68). High preprocedural plasma uPA and serum CRP levels are indicative of angina recurrence after successful PTCA, and are valuable for the prognosis of restenosis.

Association of platelet function in hypertensive patients with left ventricular hypertrophy, transient myocardial ischemia, and coronary artery disease

The aim of the study was to evaluate how platelet aggregation relates to left ventricular hypertrophy, presence of transient myocardial ischemia and coronary atherosclerosis in essential hypertensive patients. For that purpose platelet aggregation, symptom-limited treadmill-test, echocardiography and coronary angiography were performed in 65 male patients with uncomplicated essential hypertension. Aggregation was monitored both by a turbidometric method and by a method based on real-time estimation of mean aggregate size. Platelet function was also studied in 18 male normotensive subjects. Hypertensive patients with transient myocardial ischemia were characterized by increased platelet sensitivity to adenosine diphosphate, thromboxane A2 mimetic-U46619, serotonin, platelet activating factor and by increased spontaneous aggregability of platelets compared with normotensive subjects and to patients without myocardial ischemia. Platelet aggregation induced by low doses of agonists positively correlated with the degree of left ventricular hypertrophy. This study provides evidence that platelets play an important role in myocardial ischemia. Besides, it was found that platelet activity positively correlated with the degree of left ventricular hypertrophy. This may provide an additional link between left ventricular hypertrophy and coronary heart disease in hypertensive patients.

Inhibition of induced and spontaneous platelet aggregation by destabilase from medicinal leech

Destabilase, endo-epsilon-(gamma-Glu)-Lys isopeptidase from the medicinal leech, inhibits arterial thrombus formation in rats. Inhibition of platelet aggregation was supposed to be one of the main mechanisms of this phenomenon. To elucidate this question highly purified destabilase preparations were used. Aggregation was monitored both by a turbidometric method and by a method based on real-time estimation of mean aggregate size. Spontaneous aggregation of human platelets was completely blocked by destabilase. At 5 microM ADP maximal inhibition was 63%. Aggregation induced by PAF (100 nM) and collagen (0.1 mg/ml) was inhibited in the presence of destabilase by 50 and 65%, respectively. This enzyme does not activate adenylate cyclase but inhibits it. We suggest that destabilase interacts with high-affinity binding sites on the platelet plasma membrane, thus providing an anti-aggregating effect. This idea coincides with the data that destabilase primary structure has high homology with some adhesive proteins.

Platelet aggregation in patients with primary pulmonary hypertension

Platelet aggregation activity was investigated in patients with primary pulmonary hypertension in different stages of the disease. Platelets were activated with ADP and PAF. Spontaneous platelet aggregation was also measured. Spontaneous and low dose PAF-induced platelet aggregation in patients was greater than in healthy subjects and increased with the severity of the disease. It was concluded that the increased platelet activity can be related to unfavourable prognosis in these patients.