TLR3 and acute respiratory distress syndrome: Studies suggest TLR3 has little role in CLP-induced ALI, as its transcript level decreases in septic murine lungs, and TLR3 deletion does not protect CLP-treated mice from ALI.485,495 On the other hand, TLR7 in macrophages senses extracellular miRNA-146a-5p, triggers pulmonary inflammation and endothelial barrier dysfunction via TNF, contributing to sepsis-induced ARDS.496 Besides, MDA5 promotes nuclear translocation of IRF3 to initiate the transcription of signal transducer and activators of transcription 1, activating macrophage M1 polarization in septic ALI.497