Biased signaling in platelet G-protein coupled receptors

Association between platelets and in-hospital mortality in critically ill patients with tumours: a retrospective cohort study

OBJECTIVES

Platelet count is an independent predictor of mortality in patients with cancer. It remains unknown whether the platelet count is related to in-hospital mortality in severely ill patients with tumours.

DESIGN

A retrospective study based on a dataset from a multicentre cohort.

SETTING

This was a secondary analysis of data from one Electronic Intensive Care Unit Collaborative Research Database survey cycle (2014-2015).

PARTICIPANTS

The data pertaining to severely ill patients with tumours were collected from 208 hospitals located across the USA. This study initially a total of 200 859 participants. After the population was limited to patients with combined tumours and platelet deficiencies, the remaining 2628 people were included in the final data analysis.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main measure was the platelet count, and the main outcome was in-hospital mortality.

RESULTS

After adjustment for the covariates, the platelet count had a curvilinear relationship with in-hospital mortality (p<0.001). The first inflection point was 18.4 (per 10 change). On the left side of the first inflection point (platelet count ≤184 'x10ˆ9/L), an increase of 10 in the platelet count was negatively associated with in-hospital mortality (OR 0.92, 95% CI 0.89 to 0.95, p<0.001). The second inflection point was 44.5 (per 10 change). Additional increases of 10 in the platelet count thereafter were positively associated with hospital mortality (OR 1.13, 95% CI 1.00 to 1.28, p=0.0454). The baseline platelet count was in the range of 184 'x10ˆ9/L-445 'x10ˆ9/L(p=0.0525), and the hospital mortality was lower than the baseline platelet count in other ranges.

CONCLUSIONS

The relationship between platelet count and in-hospital mortality in critically ill patients with tumours was curvilinear. The lowest in-hospital mortality was associated with platelet count between 184 'x10ˆ9/Land 445 'x10ˆ9/L. This indicates that both high and low platelet count should receive attention in clinical practice.

Atypical Roles of the Chemokine Receptor ACKR3/CXCR7 in Platelet Pathophysiology

The manifold actions of the pro-inflammatory and regenerative chemokine CXCL12/SDF-1α are executed through the canonical GProteinCoupledReceptor CXCR4, and the non-canonical ACKR3/CXCR7. Platelets express CXCR4, ACKR3/CXCR7, and are a vital source of CXCL12/SDF-1α themselves. In recent years, a regulatory impact of the CXCL12-CXCR4-CXCR7 axis on platelet biogenesis, i.e., megakaryopoiesis, thrombotic and thrombo-inflammatory actions have been revealed through experimental and clinical studies. Platelet surface expression of ACKR3/CXCR7 is significantly enhanced following myocardial infarction (MI) in acute coronary syndrome (ACS) patients, and is also associated with improved functional recovery and prognosis. The therapeutic implications of ACKR3/CXCR7 in myocardial regeneration and improved recovery following an ischemic episode, are well documented. Cardiomyocytes, cardiac-fibroblasts, endothelial lining of the blood vessels perfusing the heart, besides infiltrating platelets and monocytes, all express ACKR3/CXCR7. This review recapitulates ligand induced differential trafficking of platelet CXCR4-ACKR3/CXCR7 affecting their surface availability, and in regulating thrombo-inflammatory platelet functions and survival through CXCR4 or ACKR3/CXCR7. It emphasizes the pro-thrombotic influence of CXCL12/SDF-1α exerted through CXCR4, as opposed to the anti-thrombotic impact of ACKR3/CXCR7. Offering an innovative translational perspective, this review also discusses the advantages and challenges of utilizing ACKR3/CXCR7 as a potential anti-thrombotic strategy in platelet-associated cardiovascular disorders, particularly in coronary artery disease (CAD) patients post-MI.

Saponins as Modulators of the Blood Coagulation System and Perspectives Regarding Their Use in the Prevention of Venous Thromboembolic Incidents

Saponins comprise a heterogenous group of chemical compounds containing a triterpene or steroid aglycone group and at least one sugar chain. They exist as secondary metabolites, occurring frequently in dicotyledonous plants and lower marine animals. Plant saponin extracts or single saponins have indicated antiplatelet and anticoagulant activity. Venous thromboembolism (VTE), including deep venous thrombosis and pulmonary embolism, is a multifactorial disease influenced by various patient characteristics such as age, immobility, previous thromboembolism and inherited thrombophilia. This mini-review (1) evaluates the current literature on saponins as modulators of the coagulation system, (2) discusses the impact of chemical structure on the modulation of the coagulation system, which may further provide a basis for drug or supplement design, (3) examines perspectives of their use in the prevention of VTE. It also describes the molecular mechanisms of action of the saponins involved in the prevention of VTE.