Patients with CKD display a significantly higher risk of cardiovascular and thromboembolic complications, with around half of patients with advanced CKD ultimately dying of cardiovascular disease. Paradoxically, these patients also have a higher risk of hemorrhages, greatly complicating patient therapy. Platelets are central to hemostasis, and altered platelet function resulting in either platelet hyper- or hyporeactivity may contribute to thrombotic or hemorrhagic complications. Different molecular changes have been identified that may underlie altered platelet activity and hemostasis in CKD. In this study, we summarize the knowledge on CKD-induced aberrations in hemostasis, with a special focus on platelet abnormalities. We also discuss how prominent alterations in vascular integrity, coagulation, and red blood cell count in CKD may contribute to altered hemostasis in these patients who are high risk. Furthermore, with patients with CKD commonly receiving antiplatelet therapy to prevent secondary atherothrombotic complications, we discuss antiplatelet treatment strategies and their risk versus benefit in terms of thrombosis prevention, bleeding, and clinical outcome depending on CKD stage. This reveals a careful consideration of benefits versus risks of antiplatelet therapy in patients with CKD, balancing thrombotic versus bleeding risk. Nonetheless, despite antiplatelet therapy, patients with CKD remain at high cardiovascular risk. Thus, deep insights into altered platelet activity in CKD and underlying mechanisms are important for the optimization and development of current and novel antiplatelet treatment strategies, specifically tailored to these patients who are high risk. Ultimately, this review underlines the importance of a closer investigation of altered platelet function, hemostasis, and antiplatelet therapy in patients with CKD.

Aims: Inflammation accompanies heart failure (HF) and elevated levels of inflammatory biomarkers are linked to new onset of HF. However, whether the prognostic relevance of inflammatory biomarkers is different in HF with reduced (HFrEF) and preserved ejection fraction (HFpEF) is unclear. The aim of the current study is to explore the role of inflammation on the mortality risk in patients with HF. Methods: We analysed interleukin-6 and hsCRP levels by ELISA and immunonephelometry, respectively, in HFpEF and HFrEF patients referred for coronary angiography and assessed the prognostic value in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. Results: HF was present in 1086 patients (N = 506 HFpEF; N = 580 HFrEF; mean age 65 ± 10 years; 28% female). Increasing IL-6 levels were significantly associated with increased CV mortality in HFpEF [1.5 (95% CI: 1.1–2.2), P = 0.018] but not HFrEF [HR 1.3 (95% CI: 1.0–1.7), P = 0.06] patients. High-sensitive CRP followed a similar pattern but failed to reach statistical significance after full-adjustment (HFpEF: HR 1.4 95%C I: 1.0–2.0; P = 0.065; HFrEF HR: 1.0 95% CI: 0.7–1.3; P = 0.800). Interaction analysis in patients stratified by IL-6 and N terminal pro brain natriuretic peptide (NT-proBNP) above and below the median revealed a stepwise increase in CV-mortality in HFpEF (P = 0.036) but not HFrEF patients (P = 0.220). To investigate the relationship between IL-6 and NT-proBNP, we assessed the genetic IL6-Receptor variant p.Asp358Ala (rs2228145) which is linked to impaired IL-6 receptor signalling. Homozygous carriers with HFpEF but not HFrEF exhibited significantly lower NT-pro-BNP levels compared with wildtype carriers (HFpEF 779 pg/mL ± 787 vs. 1180 pg/ mL ± 1532; P = 0.008; HFrEF 2289 pg/ mL ± 3439 vs. 2326 pg/ mL ± 3386; P = 0.94), raising the hypothesis that IL-6 signalling may play a pathophysiological role in HFpEF. Conclusions: These data suggest a predictive value of elevated IL-6 for CV-mortality in HFpEF but not in HFrEF patients.

Dyslipidaemia leads to proatherogenic oxidative lipid stress that promotes vascular inflammation and thrombosis, the pathologies that underpin myocardial infarction, stroke, and deep vein thrombosis. These prothrombotic states are driven, at least in part, by platelet hyperactivity, and they are concurrent with the appearancxe of oxidatively modified low-density lipoproteins (LDL) in the circulation. Modified LDL are heterogenous in nature but, in a general sense, constitute a prototype circulating transporter for a plethora of oxidised lipid epitopes that act as danger-associated molecular patterns. It is well-established that oxidatively modified LDL promote platelet activation and arterial thrombosis through a number of constitutively expressed scavenger receptors, which transduce atherogenic lipid stress to a complex array of proactivatory signalling pathways in the platelets. Stimulation of these signalling events underlie the ability of modified LDL to induce platelet activation and blunt platelet inhibitory pathways, as well as promote platelet-mediated coagulation. Accumulating evidence from patients at risk of arterial thrombosis and experimental animal models of disease suggest that oxidised LDL represents a tangible link between the dyslipidaemic environment and increased platelet activation. The aim of this review is to summarise recent advances in our understanding of the pro-thrombotic signalling events induced in platelets by modified LDL ligation, describe the contribution of individual platelet scavenger receptors, and highlight potential future challenges of targeting these pathways.

Oxidized low-density lipoprotein (oxLDL) and associated oxidized phosphocholine-headgroup phospholipids (oxPCs) activate blood platelets through ligation of the scavenger receptor CD36. Previously, we found that oxLDL stimulated phosphorylation of phospholipase Cγ2 (PLCγ2). However, the functional relevance of PLCγ2 phosphorylation in oxLDL-mediated platelet hyperactivity remained elusive. Here, we set out to explore the functional importance of PLCγ2 in oxLDL-mediated platelet activation using human and genetically modified murine platelets. The CD36-specific oxidized phospholipid (oxPC_CD36) triggered the generation of reactive oxygen species (ROS) in platelets under static and arterial flow conditions. The ROS generation in response to oxPC_CD36 was sustained for up to 3 h but ablated in CD36- and PLCγ2-deficient platelets. The functional importance of ROS generation in response to atherogenic lipid stress was examined through measurement of P-selectin expression. OxPC_CD36 induced P-selectin expression, but required up to 60 min incubation, consistent with the timeline for ROS generation. P-selectin expression was not observed in CD36- and PLCγ2-deficient mice. The ability of oxPC_CD36 and oxLDL to stimulate P-selectin expression was prevented by incubation of platelets with the ROS scavenger N-acetyl-cysteine (NAC) and the NOX-2 inhibitor gp91ds-tat, but not with the NOX-1 inhibitor ML171. In summary, we provide evidence that prolonged exposure to oxLDL-associated oxidized phospholipids induces platelet activation via NOX-2-mediated ROS production in a CD36- and PLCγ2-dependent manner.

Platelets are anucleate cells that primarily facilitate thrombosis and hemostasis but can also act as mediators of vascular inflammation in disease. Platelets are typically understood to do this through the release of pre-formed chemokines coupled with direct heterotypic interactions with a variety of immune cells. However, an alternative mode of action has been described where platelets are able to undertake de novo synthesis of the cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18). The primary mechanism to produce these inflammatory mediators is the activation of the NACHT leucine-rich repeat pyrin domain-containing protein 3 (NLRP3) inflammasome, a multi-protein complex that processes IL-1β and IL-18 through caspase activation. The presence and characteristics of the NLRP3 inflammasome have been widely described in a variety of nucleated cells, although its role in anucleate platelets is less clear. In the last decade, the presence of the inflammasome has been reported in platelets and linked to several diseased states including sickle cell disease, acute coronary syndrome, sepsis, and viral hemorrhagic fever. This emerging new biology of platelets, its role in platelet function, vascular inflammation, and other related areas of exploration are critically reviewed here.

Background: The clinical and prognostic implications of platelet reactivity (PR) testing in a P2Y₁₂-inhibitor naïve population are poorly understood. Objectives: This explorative study aims to assess the role of PR and explore factors that may modify elevated mortality risk in patients with altered PR. Methods: Platelet ADP-induced CD62P and CD63 expression were measured by flow-cytometry in 1520 patients who were referred for coronary angiography in the Ludwigshafen Risk and Cardiovascular Health Study (LURIC). Results: High- and Low-platelet reactivity to ADP were strong predictors of cardiovascular and all-cause mortality and risk equivalent to the presence of coronary artery disease. (High platelet reactivity 1.4 [95% CI 1.1–1.9]; Low platelet reactivity: 1.4 [95% CI 1.0–2.0]). Relative weight analysis indicated glucose control (HbA1c), renal function ([eGFR]), inflammation (high-sensitive C-reactive protein [hsCRP]) and antiplatelet therapy by Aspirin as consistent mortality risk modifiers in patients with Low- and High-platelet reactivity. Pre-specified stratification of patients by risk modifiers HbA1c (60 mL/min/1.73 m²) and CRP (<3 mg/L) was associated with a lower mortality risk, however irrespective of platelet reactivity. Aspirin treatment was associated with reduced mortality in patients with high platelet reactivity only (p for interaction: 0.02 for CV-death [<0.01 for all-cause mortality]. Conclusions: Cardiovascular mortality risk in patients with High- and Low platelet reactivity is equivalent to the presence of coronary artery disease. Targeted glucose control, improved kidney function and lower inflammation are associated with reduced mortality risk, however independent of platelet reactivity. In contrast, only in patients with High-platelet reactivity was Aspirin treatment associated with lower mortality.