Associations between arterial stiffness and platelet activation in normotensive overweight and obese young adults

Role of the NO-GC/cGMP signaling pathway in platelet biomechanics

Cyclic guanosine monophosphate (cGMP) is a second messenger produced by the NO-sensitive guanylyl cyclase (NO-GC). The NO-GC/cGMP pathway in platelets has been extensively studied. However, its role in regulating the biomechanical properties of platelets has not yet been addressed and remains unknown. We therefore investigated the stiffness of living platelets after treatment with the NO-GC stimulator riociguat or the NO-GC activator cinaciguat using scanning ion conductance microscopy (SICM). Stimulation of human and murine platelets with cGMP-modulating drugs decreased cellular stiffness and downregulated P-selectin, a marker for platelet activation. We also quantified changes in platelet shape using deep learning-based platelet morphometry, finding that platelets become more circular upon treatment with cGMP-modulating drugs. To test for clinical applicability of NO-GC stimulators in the context of increased thrombogenicity risk, we investigated the effect of riociguat on platelets from human immunodeficiency virus (HIV)-positive patients taking abacavir sulfate (ABC)-containing regimens. Our results corroborate a functional role of the NO-GC/cGMP pathway in platelet biomechanics, indicating that biomechanical properties such as stiffness or shape could be used as novel biomarkers in clinical research.

Effects of Long-Term Intervention with Losartan, Aspirin and Atorvastatin on Vascular Remodeling in Juvenile Spontaneously Hypertensive Rats

Hypertension in adolescents is associated with adverse cardiac and vascular events. In addition to lowering blood pressure, it is not clear whether pharmacological therapy in early life can improve vascular remodeling. This study aimed to evaluate the effects of long-term administration of losartan, aspirin, and atorvastatin on vascular remodeling in juvenile spontaneously hypertensive rats (SHRs). Losartan, aspirin, and atorvastatin were administered via gavage at doses of 20, 10, and 10 mg/kg/day, respectively, on SHRs aged 6-22 weeks. Paraffin sections of the blood vessels were stained with hematoxylin-eosin (H&E) and Sirius Red to evaluate the changes in the vascular structure and the accumulation of different types of collagen. The plasma levels of renin, angiotensin II (Ang II), aldosterone (ALD), endothelin-1 (ET-1), interleukin-6 (IL-6), and neutrophil elastase (NE) were determined using ELISA kits. After the 16-week treatment with losartan, aspirin, and atorvastatin, the wall thickness of the thoracic aorta and carotid artery decreased. The integrity of the elastic fibers in the tunica media was maintained in an orderly manner, and collagen deposition in the adventitia was retarded. The plasma levels of renin, ALD, ET-1, IL-6, and NE in the SHRs also decreased. These findings suggest that losartan, aspirin, and atorvastatin could improve vascular remodeling beyond their antihypertensive, anti-inflammatory, and lipid-lowering effects. Many aspects of the protection provided by pharmacological therapy are important for the prevention of cardiovascular diseases in adults and older adults.

Severe COVID-19-A Review of Suggested Mechanisms Based on the Role of Extracellular Matrix Stiffness

The severity of COVID-19 commonly depends on age-related tissue stiffness. The aim was to review publications that explain the effect of microenvironmental extracellular matrix stiffness on cellular processes. Platelets and endothelial cells are mechanosensitive. Increased tissue stiffness can trigger cytokine storm with the upregulated expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha and interleukin IL-6, and tissue integrity disruption, leading to enhanced virus entry and disease severity. Increased tissue stiffness in critically ill COVID-19 patients triggers platelet activation and initiates plague formation and thrombosis development. Cholesterol content in cell membrane increases with aging and further enhances tissue stiffness. Membrane cholesterol depletion decreases virus entry to host cells. Membrane cholesterol lowering drugs, such as statins or novel chitosan derivatives, have to be further developed for application in COVID-19 treatment. Statins are also known to decrease arterial stiffness mitigating cardiovascular diseases. Sulfated chitosan derivatives can be further developed for potential use in future as anticoagulants in prevention of severe COVID-19. Anti-TNF-α therapies as well as destiffening therapies have been suggested to combat severe COVID-19. The inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cells pathway must be considered as a therapeutic target in the treatment of severe COVID-19 patients. The activation of mechanosensitive platelets by higher matrix stiffness increases their adhesion and the risk of thrombus formation, thus enhancing the severity of COVID-19.

Modification of Platelet Count on the Association between Homocysteine and Blood Pressure: A Moderation Analysis in Chinese Hypertensive Patients

Background

Platelet consumption followed by homocysteine-induced endothelial injury suggests a crosstalk between platelet activation and homocysteine on hypertension. Platelet count has been found to modify the effect of folic acid on vascular health. However, whether platelet count could modify the contribution of homocysteine to blood pressure (BP) remains unclear.

Methods

Leveraging a community-based cross-sectional survey in 30,369 Chinese hypertensive patients (mean age 62 years, 52% female), we examined the moderation of platelet count on the association between serum homocysteine and BP by constructing hierarchical multiple regression models, adjusting for conventional risk factors. If adding the interaction term of homocysteine and platelet count could explain more variance in BP and the interaction is significant, then we believe that moderation is occurring.

Results

The association between serum homocysteine and diastolic BP was significantly stronger (β = 0.092 vs. 0.035, P = 0.004) in participants with low platelet count (<210 × 10⁹/L) than in those with high platelet count (≥210 × 10⁹/L). Adding the interaction term of homocysteine and platelet count additionally explained 0.05% of the variance in diastolic BP (P = 0.004) in participants with low platelet count (<210 × 10⁹/L) than in those with high platelet count (≥210 × 10⁹/L). Adding the interaction term of homocysteine and platelet count additionally explained 0.05% of the variance in diastolic BP (β = 0.092 vs. 0.035, P = 0.004) in participants with low platelet count (<210 × 10⁹/L) than in those with high platelet count (≥210 × 10⁹/L). Adding the interaction term of homocysteine and platelet count additionally explained 0.05% of the variance in diastolic BP (

Conclusions

The association between homocysteine and BP was significantly stronger in participants with low vs. high platelet count and was partially moderated by platelet count. These results indicate that platelet count may be useful in the identification of individuals who are most beneficial to reducing-homocysteine treatments but this usefullness still needs further investigation.

Preoperative Pulse Pressure and Adverse Postoperative Outcomes: A Meta-Analysis

OBJECTIVE

To evaluate the association between preoperative pulse pressure (PP) and the incidences of renal, neurologic, cardiac, and mortality outcomes after surgery.

DESIGN

Systematic review and meta-analysis of cohort studies.

SETTING

Hospitals.

PARTICIPANTS

Patients who underwent cardiac or noncardiac surgeries.

INTERVENTION

The preoperative PP was measured.

MEASUREMENT AND MAIN RESULTS

Relevant cohort studies were obtained by systematic search of PubMed and Embase databases. A randomized effect model was used to pool the results. The multivariate adjusted risk ratio (RR) and its 95% confidence intervals (CI) were calculated to reflect the association between preoperative PP and adverse postoperative outcomes. Twelve cohort studies that included 40,143 patients who had undergone cardiac, vascular, or noncardiac surgery were included in the meta-analysis. The results showed that above a threshold of 40 mmHg, an increase in preoperative PP of 10 mmHg was independently associated with increased risk for renal events (adjusted RR: 1.13, 95% CI 1.08-1.19, p < 0.001; I² = 0%), neurologic events (adjusted RR: 1.75, 95% CI 1.01-3.02, p = 0.04; I² = 70%), cardiac events (adjusted RR: 1.19, 95% CI 1.03-1.37, p = 0.01; I² = 0%), major cardiovascular adverse events (adjusted RR: 1.62, 95% CI 1.10-2.41, p = 0.02; I² = 0%), and overall mortality (adjusted RR: 1.13, 95% CI 1.07-1.20, p < 0.001; I² = 0%) after surgery.

CONCLUSIONS

Patients with higher-than-normal preoperative PP are at increased risk for adverse postoperative outcomes.

Leptin as a Mediator of Obesity-Induced Hypertension

Hypertension and associated cardiovascular diseases represent the most common health complication of obesity and the leading cause of morbidity and mortality in overweight and obese patients. Emerging evidence suggests a critical role for the central nervous system particularly the brain action of the adipocyte-derived hormone leptin in linking obesity and hypertension. The preserved ability of leptin to cause cardiovascular sympathetic nerve activation despite the resistance to the metabolic actions of the hormone appears essential in this pathological process. This review describes the evidence supporting the neurogenic bases for obesity-associated hypertension with a particular focus on the neuronal and molecular signaling pathways underlying leptin's effects on sympathetic nerve activity and blood pressure.