Initial therapeutic anticoagulation with rivaroxaban compared to prophylactic therapy with heparins in moderate to severe COVID-19: results of the COVID-PREVENT randomized controlled trial.

BACKGROUND: COVID-19 is associated with a prothrombotic state. Current guidelines recommend prophylactic anticoagulation upon hospitalization. METHODS: COVID-PREVENT, an open-label, multicenter, randomized, clinical trial enrolled patients (≥ 18 years) with moderate to severe COVID-19 and age-adjusted D-dimers > 1.5 upper limit of normal (ULN). The participants were randomly assigned (1:1) to receive either therapeutic anticoagulation with rivaroxaban 20 mg once daily or thromboprophylaxis with a heparin (SOC) for at least 7 days followed by prophylactic anticoagulation with rivaroxaban 10 mg once daily for 28 days or no thromboprophylaxis. The primary efficacy outcome was the D-dimer level and the co-primary efficacy outcome the 7-category ordinal COVID-19 scale by WHO at 7 days post randomization. The secondary outcome was time to the composite event of either venous or arterial thromboembolism, new myocardial infarction, non-hemorrhagic stroke, all-cause death or progression to intubation and invasive ventilation up to 35 days post randomization. RESULTS: The primary efficacy outcome D-dimer at 7 days was not different between patients assigned to therapeutic (n = 55) or prophylactic anticoagulation (n = 56) (1.21 mg/L [0.79, 1.86] vs 1.27 mg/L [0.79, 2.04], p = 0.78). In the whole study population D-dimer was significantly lower at 7 days compared to baseline (1.05 mg/L [0.75, 1.48] vs 1.57 mg/L [1.13, 2.19], p < 0.0001). Therapy with rivaroxaban compared to SOC was not associated an improvement on the WHO 7-category ordinal scale at 7 days (p = 0.085). Rivaroxaban improved the clinical outcome measured by the score in patients with a higher baseline D-dimer > 2.0 ULN (exploratory analysis; 0.632 [0.516, 0.748], p = 0.026). The secondary endpoint occurred in 6 patients (10.9%) in the rivaroxaban group and in 12 (21.4%) in the SOC group (time-to-first occurrence of the components of the secondary outcome: HR 0.5; 95% CI 0.15-1.67; p = 0.264). There was no difference in fatal or non-fatal major or clinically relevant non-major bleeding between the groups. CONCLUSIONS: Therapeutic anticoagulation with rivaroxaban compared to prophylactic anticoagulation with a heparin did not improve surrogates of clinical outcome in patients with moderate to severe COVID-19. Whether initial rivaroxaban at therapeutic doses might be superior to thromboprophylaxis in patients with COVID-19 and a high risk as defined by D-dimer > 2 ULN needs confirmation in further studies.

Caffeine enhances endothelial repair by an AMPK-dependent mechanism.

OBJECTIVE: Migratory capacity of endothelial progenitor cells (EPCs) and mature endothelial cells (ECs) is a key prerequisite for endothelial repair after denuding injury or endothelial damage. METHODS AND RESULTS: We demonstrate that caffeine in physiologically relevant concentrations (50 to 100 micromol/L) induces migration of human EPCs as well as mature ECs. In patients with coronary artery disease (CAD), caffeinated coffee increased caffeine serum concentration from 2 micromol/L to 23 micromol/L, coinciding with a significant increase in migratory activity of patient-derived EPCs. Decaffeinated coffee neither affected caffeine serum levels nor migratory capacity of EPCs. Treatment with caffeine for 7 to 10 days in a mouse-model improved endothelial repair after denudation of the carotid artery. The enhancement of reendothelialization by caffeine was significantly reduced in AMPK knockout mice compared to wild-type animals. Transplantation of wild-type and AMPK(-/-) bone marrow into wild-type mice revealed no difference in caffeine challenged reendothelialization. ECs which were depleted of mitochondrial DNA did not migrate when challenged with caffeine, suggesting a potential role for mitochondria in caffeine-dependent migration. CONCLUSIONS: These results provide evidence that caffeine enhances endothelial cell migration and reendothelialization in part through an AMPK-dependent mechanism, suggesting a beneficial role for caffeine in endothelial repair.

Non-canonical Wnt signaling enhances differentiation of human circulating progenitor cells to cardiomyogenic cells.

Human endothelial circulating progenitor cells (CPCs) can differentiate to cardiomyogenic cells during co-culture with neonatal rat cardiomyocytes. Wnt proteins induce myogenic specification and cardiac myogenesis. Here, we elucidated the effect of Wnts on differentiation of CPCs to cardiomyogenic cells. CPCs from peripheral blood mononuclear cells were isolated from healthy volunteers and co-cultured with neonatal rat cardiomyocytes. 6-10 days after co-culture, cardiac differentiation was determined by alpha-sarcomeric actinin staining of human lymphocyte antigen-positive cells (fluorescence-activated cell-sorting analysis) and mRNA expression of human myosin heavy chain and atrial natriuretic peptide. Supplementation of co-cultures with Wnt11-conditioned medium significantly enhanced the differentiation of CPCs to cardiomyocytes (1.7+/-0.3-fold), whereas Wnt3A-conditioned medium showed no effect. Cell fusion was not affected by Wnt11-conditioned medium. Because Wnts inhibit glycogen synthase kinase-3beta, we further determined whether the glycogen synthase kinase-3beta inhibitor LiCl also enhanced cardiac differentiation of CPCs. However, LiCl (10 mM) did not affect CPC differentiation. In contrast, Wnt11-conditioned medium time-dependently activated protein kinase C (PKC). Moreover, the PKC inhibitors bisindolylmaleimide I and III significantly blocked differentiation of CPCs to cardiomyocytes. PKC activation by phorbol 12-myristate 13-acetate significantly increased CPC differentiation to a similar extent as compared with Wnt11-conditioned medium. Our data demonstrate that Wnt11, but not Wnt3A, augments cardiomyogenic differentiation of human CPCs. Wnt11 promotes cardiac differentiation via the non-canonical PKC-dependent signaling pathway.

Glycogen synthase kinase-3 couples AKT-dependent signaling to the regulation of p21Cip1 degradation.

Signaling via the phosphoinositide 3-kinase (PI3K)/AKT pathway is crucial for the regulation of endothelial cell (EC) proliferation and survival, which involves the AKT-dependent phosphorylation of the DNA repair protein p21(Cip1) at Thr-145. Because p21(Cip1) is a short-lived protein with a high proteasomal degradation rate, we investigated the regulation of p21(Cip1) protein levels by PI3K/AKT-dependent signaling. The PI3K inhibitors Ly294002 and wortmannin reduced p21(Cip1) protein abundance in human umbilical vein EC. However, mutation of the AKT site Thr-145 into aspartate (T145D) did not increase its protein half-life. We therefore investigated whether a kinase downstream of AKT regulates p21(Cip1) protein levels. In various cell types, AKT phosphorylates and inhibits glycogen synthase kinase-3 (GSK-3). Upon serum stimulation of EC, GSK-3beta was phosphorylated at Ser-9. Site-directed mutagenesis revealed that GSK-3 in vitro phosphorylated p21(Cip1) specifically at Thr-57 within the Cdk binding domain. Overexpression of GSK-3beta decreased p21(Cip1) protein levels in EC, whereas the specific inhibition of GSK-3 with lithium chloride interfered with p21(Cip1) degradation and increased p21(Cip1) protein about 10-fold in EC and cardiac myocytes (30 mm, p < 0.001). These data indicate that GSK-3 triggers p21(Cip1) degradation. In contrast, stimulation of AKT increases p21(Cip1) via inhibitory phosphorylation of GSK-3.