CXCL8 and COVID-19: We further showed the significantly increased phosphorylation of the p65 subunits of NF-κB in cells after stimulating with COVID-19 patient–derived EVs, compared with those from healthy control subjects (2.77 ± 0.06-fold versus 1.01 ± 0.13-fold, P < 0.005, Fig. 6E), accompanied by elevated proinflammatory cytokine/chemokine (e.g., IL-1β, TNF-α and IL-8) levels.