TLR2 and acute respiratory distress syndrome: Li et al. [69] demonstrated that HMGB1 participates in ALI by activating double-stranded RNA-dependent protein kinase (PKR) in macrophages and inducing macrophage (M1) polarization via TLR2- and TLR4-mediated NF-κB signaling pathways in a mouse model of ALI induced by the bacterial endotoxin lipopolysaccharide (LPS).