The endothelial cells participate in the regulation of local and systemic inflammation by generating or responding to cytokines that characterize the cytokine storm in COVID-19, including interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-α (9), which finally leads to a pro-thrombotic phenotype in patients with severe COVID-19. Here, IL6 is linked to COVID-19.