ABSTRACT
Background: Neutrophil extracellular traps (NETs) release is the one of the main mechanisms behind hypercoagulability and disease severity in severe acute respiratory syndromes. The identification of drugs capable of inhibiting this pathological mechanism is mandatory. Aim(s): Neutrophil extracellular traps (NETs) release is the one of the main mechanisms behind hypercoagulability and disease severity in severe acute respiratory syndromes. The identification of drugs capable of inhibiting this pathological mechanism is mandatory. Method(s): Healthy neutrophils (20 x 103/well) were stimulated with phorbol myristate acetate (PMA) or sera from severe COVID-19 patients (n = 16) in the presence or absence of dipyridamole (10 muM), aspirin (1 mM) and heparin (50 mug/mL). Neutrophils nuclei were stained with nuclear red and incubated with a medium containing the non-permeable cell membrane marker Sytox Green. Cell images were obtained using IncuCyte ZOOM and the number of cells that suffered netosis was monitored over time. NETs release was determined after 1 h of incubation and the percentage of NETs was calculated dividing the number of green cells by the total number of cells per well. Result(s): COVID-19 induced NETs was lower in neutrophils pretreated with heparin (median 2.6%, IQR 2.6-2.9) than in non-treated neutrophils (median 3.6%, IQR 3.2-4.0, p < 0.0001). Pretreatment with dipyridamole and aspirin did not change the effect of COVID-19 sera in inducing NETs. A similar pattern of inhibition was observed with PMA stimulation, in which heparin decreased NETs by 3 times (NETs after PMA 43.2% and NETs after PMA and heparin 14.8%) while dipyridamole and aspirin did not significantly affect the release of PMA-induced NETs (Figure 1). Figure 2 illustrates the identification of NETs. Conclusion(s): Heparin was capable of inhibiting in vitro NETs release induced by COVID-19, while dipyridamole and aspirin had no significant effect on this process. Such findings are in line with evidence that heparin use can improve COVID-19 prognosis. (Figure Presented).
ABSTRACT
Background : Prophylactic anticoagulation is now considered standard-of-care for hospitalized COVID-19 patients . Since evidence-based guidelines for thrombo-prophylaxis are lacking, clinical practice has been based evidence showing a high risk of venous thromboembolism (VTE) among these patients. Aims : To evaluate the change in anticoagulation practice patterns in hospitalized patients with COVID-19 among Hemostasis and Thrombosis (H&T) experts in Latin America. Methods : An invitation was sent by email and website to CLAHT members. The same questionnaire was issued twice: May-June and August-September 2020. with five multiple-choice questions regarding the use of standard or weight-adjusted dosing (SWAD), intermediate or full-dose (IFD) of low molecular weight heparin (LMWH), or no prophylaxis in the following scenarios: i.Hospitalized patients without comorbidities or ii. with comorbidities and D-dimer (DD) levels three-fold above reference values;iii. Patients on mechanical ventilation (MV), iv. Patients on MV with suspected VTE;iv.LMWH management based solely on DD. Differences between surveys were analyzed using chi-square test. Results : The first and second surveys were answered by 200 and 174 individuals respectively, representing themselves or institutional practices. Distribution of participants by country is shown in Table 1. Clinical practice was heterogeneous. When comparing surveys, we found that preference for IDF for non-ICU patients without comorbidities increased (6.4%-14%) while SWAD decrease from 88.6% to 72%. IFD preference also increased from (40.6%-49%) for patients with comorbidities and high DD. Half (49%) suggested using IFD for ICU patients without VTE, while 90% preferred IFD for established or suspected VTE. More aggressive prophylaxis was favored initially in patients based on DD levels 6-fold above baseline, decreasing by 20% (from 60.6% to 49.1%) in the second survey. Conclusions : Prophylactic anticoagulation for COVID-19 varied, with a trend towards a decrease in preference for IFD, likely reflecting reported bleeding incidents. Awaited final publication of results from prospective studies will likely homogenize clinical practice worldwide.