Figure 4

Real-time monitoring of HUVEC barrier dysfunction in response to TNFα+/−HDLs. Human umbilical vein endothelial cells (25,000 cells/well) were seeded on gelatin-coated xCELLigence 16 well E-plates. HDL were isolated from plasma of 16 controls and 8 D1 COVID ICU patients by ultracentrifugation and pooled into two groups: “Control HDL" and “COVID+ HDL”. The cell index was recorded continuously until confluence, when a plateau was reached [indicated cell growth in (A)]. Cells were then serum-deprived (- Fetal Calf Serum, FCS) for 6 h and then stimulated with 30 ng/mL TNFα+/−HDLs from COVID-19 patients or controls at 0.2 mg/mL. Cell indexes were normalized after stimulation [as indicated by the vertical line, in (A), 30 min. after the stimulation]. A magnification showing TNFα, TNFα + COVID + HDL and TNFα + control HDL is presented in (B). Representative results from 2 independent experiments. HDLs isolated from each patient and matched controls (2 controls/patients) were analyzed separately (Supplementary Fig. 4A).