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.

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.

Effects of dark chocolate on endothelial function in patients with non-alcoholic steatohepatitis

BACKGROUND AND AIM

Oxidative stress plays a pivotal role in inducing endothelial dysfunction and progression from simple fatty liver steatosis (FLD) to non-alcoholic steatohepatitis (NASH). Polyphenols could reduce oxidative stress and restore endothelial function by inhibiting the nicotinamide-adenine-dinucleotide-phosphate (NADPH) oxidase isoform Nox2. The aim of this study was to assess endothelial function and oxidative stress in a population affected by simple FLD and NASH. Furthermore, we analysed the effect of high vs low content of cocoa polyphenols on endothelial function and oxidative stress in patients with NASH.

METHODS

In a cross-sectional study we analysed endothelial function, as assessed by flow-mediated dilation (FMD), and oxidative stress, as assessed by Nox2 activation, serum isoprostanes and nitric oxide bioavailability (NOx), in patients with NASH (n = 19), FLD (n = 19) and controls (n = 19). Then, we performed a randomized, cross-over study in 19 subjects with NASH comparing the effect of 14-days administration of 40 g of chocolate at high (dark chocolate, cocoa >85%) versus low content (milk chocolate, cocoa <35%) of polyphenols on FMD and oxidative stress. Compared to controls, NASH and FLD patients had higher Nox2 activity and isoprostanes levels and lower FMD and NOx, with a significant gradient between FLD and NASH. The interventional study showed that, compared to baseline, FMD and NOx increased (from 2.9 ± 2.4 to 7.2 ± 3.0% p < 0.001 and from 15.9 ± 3.6 to 20.6 ± 4.9 μM, p < 0.001, respectively) in subjects given dark but not in those given milk chocolate. A simple linear regression analysis showed that Δ (expressed by difference of values between before and after 14 days of chocolate assumption) of FMD was associated with Δ of Nox2 activity (Rs = -0.323; p = 0.04), serum isoprostanes (Rs: -0.553; p < 0.001) and NOx (Rs: 0.557; p < 0.001).

CONCLUSIONS

Cocoa polyphenols improve endothelial function via Nox2 down-regulation in NASH patients.

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.

Short-term in vivo modifications of platelet NADPH oxidase 2 (NOX2) and prostaglandin F2α in HIV-1 patients on abacavir-based therapies

OBJECTIVES

The aim of the study was to investigate the in vivo effect of abacavir (ABC) on platelet oxidative stress.

METHODS

We performed a randomized pilot study including 39 HIV-1-infected patients, 17 on zidovudine/lamivudine (ZDV/3TC) and 22 on tenofovir/emtricitabine (TDF/FTC). Ten patients on ZDV/3TC and eight patients on TDF/FTC were randomly allocated to switching the nucleoside backbone to ABC/3TC. At baseline and after 6 months, platelet oxidative stress was assessed by platelet NADPH oxidase 2 (NOX2)-derived peptide (sNOX2-dp), a marker of NOX2 activation, and platelet prostaglandin F_2α (8-iso-PGF_2α ). Platelet activation was measured by soluble CD40L (sCD40L).

RESULTS

At baseline, no differences between ZDV/3TC or TDF/FTC recipients were found. After 6 months, patients switching from ZDV/3TC showed a decrease of sNOX2-dp (from 20.9±5.7 to 12.5±3.8 pg/ml, p=0.002) and 8-iso-PGF_2α (from 154.3±41.9 to 122.9±28.0 pmol/l, p=0.025). No effects on platelet oxidative stress biomarkers were observed in subjects from TDF/FTC, who showed a significant increase in blood glucose (p=0.043) and total cholesterol (p=0.027). ABC showed no effect on sCD40L levels in both groups.

CONCLUSIONS

ABC reduced platelet sNOX2-dp and 8-iso-PGF_2α in HIV-1 subjects switching from ZDV/3TC but not in those from TDF/FTC after 6 months. No changes in platelet activation were found in both groups.

Cytoprotective and Antioxidant Effects of Steen Solution on Human Lung Spheroids and Human Endothelial Cells

Respiratory diseases represent a major healthcare burden worldwide. Lung transplantation (LTx) is the "gold standard" for end-stage patients, strongly limited by shortage of available/suitable donor lungs. Normothermic ex vivo lung perfusion (EVLP) has significantly increased the number of lungs suitable for transplantation. Steen solution is used for EVLP, but the mechanisms involved in its beneficial properties remain to be clarified. We investigated the effects of Steen solution in an in vitro protocol of cold starvation and normothermic recovery on human lung spheroids, named pneumospheres (PSs), containing epithelial/basal cells, and on endothelial human umbilical vein endothelial cells (HUVEC). Steen solution significantly preserved the viability of PSs, reduced reactive oxygen species (ROS) release by PSs and HUVECs, decreased NADPH-oxidase (NOX) activity in PSs, and reduced inflammatory cytokines expression levels in HUVECs. Steen solution was able to specifically reduce NADPH oxidase 2 (NOX2) isoform activation, particularly in PSs, as detected by soluble-NOX2 peptide and p47-phosphorylation. Interestingly, a specific NOX2 inhibitor could partly mimic the pro-survival effect of Steen on PSs. We provide the first evidence that Steen solution can preserve lung epithelial/progenitor cells viability partially through NOX2 downregulation, and exert antioxidant effects on parenchymal cells, with consequent ROS reduction. These results suggest that NOX2 inhibition might be an additional strategy to reduce cellular damage during LTx procedures.

Effects of dark chocolate on NOX-2-generated oxidative stress in patients with non-alcoholic steatohepatitis

BACKGROUND

Activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is considered a pathogenetic mechanism determining fibrosis and disease progression in non-alcoholic steatohepatitis (NASH). Polyphenols exert antioxidant action and inhibit NADPH oxidase in humans.

AIM

To analyse the effect of cocoa polyphenols on NADPH oxidase isoform 2 (NOX2) activation, oxidative stress and hepatocyte apoptosis in a population affected by NASH.

METHODS

In a cross-sectional study comparing 19 NASH and 19 controls, oxidative stress, as assessed by serum NOX2 activity and F2-isoprostanes, and hepatocyte apoptosis, as assessed by serum cytokeratin-18 (CK-18) levels, were measured. Furthermore, the 19 NASH patients were randomly allocated in a crossover design to 40 g/day of dark chocolate (>85% cocoa) or 40 g/day of milk chocolate (<35% cocoa), for 2 weeks. sNOX2-dp, serum isoprostanes and CK-18 were assessed at baseline and after 2 weeks of chocolate intake.

RESULTS

Compared to controls, NASH patients had higher sNOX2-dp, serum isoprostanes and CK-18 levels. A significant difference for treatments was found in subjects with respect to sNOX2-dp, serum isoprostanes and serum CK-18. The pairwise comparisons showed that, compared to baseline, after 14 days of dark chocolate intake, a significant reduction in sNOX2-dp serum isoprostanes and CK-18 M30 was found. No change was observed after milk chocolate ingestion. A simple linear regression analysis showed that ∆ of sNOX2-dp was associated with ∆ of serum isoprostanes.

CONCLUSION

Cocoa polyphenols exert an antioxidant activity via NOX2 down-regulation in NASH patients.

Dark chocolate inhibits platelet isoprostanes via NOX2 down-regulation in smokers

BACKGROUND

Dark chocolate is reported to decrease platelet activation but the underlying mechanism is still undefined. Dark chocolate is rich in polyphenols that could exert an antiplatelet action via inhibition of oxidative stress. The aim of the present study was to assess if dark chocolate inhibits platelet reactive oxidant species (ROS) formation and platelet activation.

METHODS

Twenty healthy subjects (HS) and 20 smokers were randomly allocated to receive 40 g of dark (cocoa > 85%) or milk chocolate (cocoa < 35%) in a cross-over, single-blind study. There was an interval of 7 days between the two phases of the study. At baseline and 2 h after chocolate ingestion, platelet recruitment (PR), platelet ROS, platelet isoprostane 8-ISO-prostaglandin F2α (8-iso-PGF2α), Thromboxane (TxA2) and platelet activation of NOX2, the catalytic sub-unit of NADPH oxidase, and serum epicatechin were measured.

RESULTS

Compared with HS, smokers showed enhanced PR, platelet formation of ROS and eicosanoids and NOX2 activation. After dark chocolate, platelet ROS (-48%, P < 0.001), 8-iso-PGF2α (-10%, P < 0.001) and NOX2 activation (-22%, P < 0.001) significantly decreased; dark chocolate did not affect platelet variables in HS. No effect of milk chocolate was detected in both groups. Serum epicatechin increased after dark chocolate in HS (from 0.454 ± 0.3 nm to 118.3 ± 53.7 nm) and smokers (from 0.5 ± 0.28 nm to 120.9 ± 54.2 nm). Platelet incubation with 0.1-10 μm catechin significantly reduced PR, platelet 8-iso-PGF2α and ROS formation and NOX2 activation only in platelets from smokers.

CONCLUSIONS

Dark chocolate inhibits platelet function by lowering oxidative stress only in smokers; this effect seems to be dependent on its polyphenolic content.