TLR4 and acute respiratory distress syndrome: During ARDS,the activation of toll-like receptors (TLRs) suchas TLR4 via lipopolysaccharide (LPS) stimulation induces an initialsystemic pro-inflammatory phase characterized by a massive releaseof pro-inflammatory mediators such as cytokines/chemokines and theactivation of proteolytic cascades, including the coagulation andcomplement system.7,8 Therefore, the clinical symptomsof patients with ARDS in many ways correspond to the pathophysiologyseen during severe COVID-19 disease.