Relationship between proprotein convertase subtilisin/kexin type 9 (PCSK9) and thrombotic events in primary antiphospholipid syndrome. The multicenter ATHERO-APS study

Background

The proprotein convertase subtilisin/kexin type 9 (PCSK9) is a novel cardiovascular risk factor. Levels of PCSK9 in thrombotic primary antiphospholipid syndrome (PAPS) have never been investigated.

Methods

Cross sectional comparison of baseline characteristics of 91 PAPS patients enrolled in the multicenter ATHERO-APS cohort study. PCSK9 levels were categorized into tertiles and the association with arterial and recurrent thrombosis were assessed by univariable and multivariable regression analysis.

Results

Median age was 51 years and 71.4% (n=65) were women. Overall, 33% (n=30) experienced an arterial event while 31% (n=28) had recurrent thrombotic events. Median PCSK9 levels were 1243 (1100–1650) pg/ml. Patients in the third PCSK9 tertile (>1458 pg/ml) showed a higher prevalence of dyslipidemia, lupus anticoagulant positivity and a history of previous arterial and recurrent thrombosis than patients in the first and second tertile. PCSK9 levels were higher in arterial than venous thrombosis (1502 vs. 1180 pg/ml, p=0.002), and in patients with recurrent vs isolated thrombosis (1680 vs. 1150 pg/m, p<0.001). High plasma PCSK9 levels were associated with a 4-fold increase risk for arterial events and with a 10-fold increase risk for recurrent thrombosis after adjustment for confounding factors.

Conclusion

These preliminary data suggest that in PAPS, PCSK9 levels are associated with arterial and recurrent thrombosis. Its role as a possible therapeutic target in PAPS needs further studies.

Funding Acknowledgement

Type of funding sources: None.

Testosterone-to-estradiol ratio and platelet thromboxane release in ischemic heart disease: the EVA project

BACKGROUND

Data on the interplay between sexual hormones balance, platelet function and clinical outcomes of adults with ischemic heart disease (IHD) are still lacking.

OBJECTIVE

To assess the association between the Testosterone (T)-to-Estradiol (E2) Ratio (T/E2) and platelet activation biomarkers in IHD and its predictive value on adverse outcomes.

METHODS

The EVA study is a prospective observational study of consecutive hospitalized adults with IHD undergoing coronary angiography and/or percutaneous coronary interventions. Serum T/E2 ratios E2, levels of thromboxane B₂ (TxB₂) and nitrates (NO), were measured at admission and major adverse events, including all-cause mortality, were collected during a long-term follow-up.

RESULTS

Among 509 adults with IHD (mean age 67 ± 11 years, 30% females), males were older with a more adverse cluster of cardiovascular risk factors than females. Acute coronary syndrome and non-obstructive coronary artery disease were more prevalent in females versus males. The lower sex-specific T/E2 ratios identified adults with the highest level of serum TxB₂ and the lowest NO levels. During a median follow-up of 23.7 months, the lower sex-specific T/E2 was associated with higher all-cause mortality (HR 3.49; 95% CI 1.24-9.80; p = 0.018). In in vitro, platelets incubated with T/E2 ratios comparable to those measured in vivo in the lowest quartile showed increased platelet activation as indicated by higher levels of aggregation and TxB₂ production.

CONCLUSION

Among adults with IHD, higher T/E2 ratio was associated with a lower long-term risk of fatal events. The effect of sex hormones on the platelet thromboxane release may partially explain such finding.

Prevalence of heart failure with preserved ejection fraction in antiphospholipid antibodies syndrome. The multicenter ATHERO-APS study

Background

The prevalence of heart failure with preserved ejection fraction (HFpEF) in patients with antiphospholipid syndrome (APS) is unknown.

Methods

Prospective multicenter cohort study including 125 patients: 91 primary APS (PAPS), 18 APS-SLE, and 16 carriers. HFpEF was diagnosed according to the 2019 European Society of Cardiology criteria: patients with ≥5 points among major and minor functional and morphological criteria including NT-ProBNP >220 pg/ml, left atrial (LA) enlargement, increased left ventricular filling pressure.

Results

Overall, 18 (14.4%) patients were diagnosed with HFpEF; this prevalence increased from 6.3% in carriers to 13.2% in PAPS and 27.8% in APS-SLE (Figure). Patients with HFpEF were older and with a higher prevalence of hypertension and previous arterial events. At logistic regression analysis, age, arterial hypertension, anticardiolipin antibodies IgG >40 GPL (odds ratio [OR] 3.43, 95% Confidence Interval [CI] 1.09–10.77, p=0.035), anti β-2-glycoprotein-I IgG >40 GPL (OR 5.28, 1.53–18.27, p=0.009), lupus anticoagulants DRVVT >1.25 (OR 5.20, 95% CI 1.10–24.68, p=0.038), (OR 3.56, 95% CI 1.11–11.47, p=0.033) and triple positivity (OR 3.56, 95% CI 1.11–11.47, p=0.033) were associated with HFpEF after adjustment for age and sex.

Discussion

HFpEF has a clinically relevant prevalence in patients with APS. The role of antiphospholipid antibodies in the pathogenesis and prognosis of HFpEF needs to be investigated.

Funding Acknowledgement

Type of funding sources: None.

The platelets behaviour in non-alcoholic fatty liver disease. A potential role for antiplatelets drugs?

Background and purpose

Previous studies showed a favorable effect of aspirin, which irreversibly acetylates cyclooxygenase-1 (COX1) so preventing Thromboxane (Tx) A2 biosynthesis, in non-alcoholic steatohepatitis (NASH) and its sequelae. However, the behavior of COX1 in NASH patients is still unknown.

Methods

We conducted a cross-sectional study on 44 outpatients with NASH, 50 subjects with simple steatosis (NAFL) and 50 subjects without hepatic steatosis balanced for age, gender and BMI. Serum TxB2, a stable metabolite of TxA2, and urinary 11-dehydro-TxB2, as markers of COX1 activation, plasma soluble P-selectin (sP-selectin), a maker of in vivo platelet activation, serum bacterial lipopolysaccharide (LPS) and serum zonulin, a marker of gut permeability, were measured.

Results

Urinary 11-dehydro-TxB2 (p<0.001) and serum TxB2 (p<0.001) levels as well as sP-selectin (p<0.001) were significantly higher in patients with NASH/NAFL compared to the controls (figure 1); the markers of COX1 activation significantly correlated with sP-selectin (p<0.001). Serum LPS was higher in patients with NASH compared with NAFL and controls (p<0.001) and serum zonulin was significantly higher in patients with NASH as compared to controls (p=0.031). A positive correlation (rS=0.37; p<0.001) was observed between serum LPS and serum zonulin. Moreover, serum LPS correlated with serum and urinary 11-dehydro-TxB2 (rS=0.30; p<0.001 and rS=0.61; p<0.001, respectively) and with sP-Selectin (rS=0.32; p<0.001) (figure). At multivariate analysis, LPS above median (OR=3.15, p=0.015) and liver diagnosis (NAFL vs. Controls: OR=6.54; p<0.001 and NASH vs Controls: OR=4.54; p=0.007) were independently associated with sP-selectin above median (table).

Conclusions

Patients with NAFLD display enhanced platelet activation, which is associated to COX1 up-regulation. LPS increased by impaired gut permeability may favor platelet activation.

Figure 1

Funding Acknowledgement

Type of funding source: None

P5454PCSK9 as a predictor of cardiovascular events in atrial fibrillation: role of platelet activation

Background

High circulating levels of proprotein convertase subtilisin/kexin 9 (PCSK9) were shown to be predictive of cardiovascular events (CVEs) in patients with atrial fibrillation (AF). Because high PCSK9 plasma levels were significantly correlated with 11-dehydro-thromboxane B2 (11-dh-TxB2), a marker of platelet activation, it is conceivable to hypothesize a direct effect of PCSK9 on platelet activation but the mechanism is still unclear.

Purpose

We evaluated the association between PCSK9 and platelet activation in FA patients and investigate the possible molecular mechanism involved.

Methods

According to our previous prospective study, we conducted a post-hoc analysis including 50 patients with baseline PCSK9 below and 50 above the median value of 1200pg/ml. The two groups were balanced for age and sex. In vivo platelet activation was assessed by aggregation (PA), recruitment, plasma thromboxane B2 (TxB2) formation and sPselectin levels. As markers of oxidative stress we used sNox2-dp, H2O2 production, urinary isoprostanes and oxLDL. To asses the role of PCSK9 in platelet activation, we performed an in vitro study with platelets from healthy subjects (n=5) added with PCSK9 concentrations achievable in human circulation (1000pg/ml and 2000pg/ml) measuring PA, TxB2, isoprostanes production, Nox2 activation, H2O2 production, oxLDL, p38, p47 and PLA2 phosphorylation.

Results

We observed an increased of platelet activation and oxidative stress in patients with PCSK9 levels above median (1200pg/ml) compared to those below (p<0.05). A significant correlation between plasma levels of PCSK9 and markers of platelet activation and markers of oxidative stress were found. In vitro study demonstrated that PCSK9, at the concentration similar to that of patients with CVEs, was able to increase platelet activation act by binding oxLDL receptor. PCSK9 dependent platelet activation is mediated by p47 phosphorylation, a key step in Nox2 activation and is mediated by the PLA2 phosporylation.

Conclusions

PCSK9, at concentration achievable in patients with CVEs, increased platelet aggregation via oxLDL receptor with a pathway involving Nox2 activation.

Low-grade endotoxemia, gut permeability and platelet activation in patients with impaired fasting glucose

BACKGROUND AND AIM

Impaired fasting glucose (IFG) is associated with an increased risk of cardiovascular disease but the underlying mechanisms are still unclear. Aim of the study was to investigate the interplay between platelet activation, lipopolysaccharides (LPS) and markers of oxidative stress in patients with IFG and control subjects.

METHODS AND RESULTS

We performed a cross-sectional study including 35 patients with IFG and 35 control subjects who were well comparable for age, sex, body mass index and smoking history. Serum levels of LPS, zonulin (a marker of gut permeability), oxidized LDL and plasma levels of soluble P-selectin, were measured. Patients with IFG had significantly higher levels of sP-selectin, LPS, zonulin and oxLDL compared to control subjects. The IFG status (beta coefficient: 0.518, p < 0.001), higher LPS (beta coefficient: 0.352, p = 0.001) and female sex (beta coefficient: 0.179, p = 0.042) were independently associated with higher sP-selectin; in addition, oxLDL was positively associated with sP-selectin (r = 0.530, p < 0.001) and LPS (r = 0.529, p = 0.001). In IFG patients, we found a significant association between LPS and zonulin (r = 0.521, p = 0.001); this association was confirmed at multivariable analysis (beta coefficient: 0.512, p = 0.007).

CONCLUSION

Our study provides evidence that patients with IFG have increased platelet activation, and suggests LPS as a potential trigger for in vivo platelet activation in this patient population.