CXCL8 and COVID-19: In vitro and in vivo, it inhibits the activation of pro-inflammatory transcription factors such as nuclear factor-kappa B (NF-κB) and pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, and IL-8 [125,188,189,190], which are elevated in patients with severe COVID-19 and contribute to the cytokine storm [32,46,59,94,191,192,193,194].