TLR4 and acute respiratory distress syndrome: As shown in Figure 5, compared with the control group, the expressions of TLR4, p-IKKα/β, p-IκBα, and p-NF-κB were significantly upregulated in the lungs of LPS-induced ALI rats, and IKKα/β, IκBα, and NF-κB expression were significantly downregulated.