Besides, it has been supposed that miR-451 in the UCMSC- exosomes reduced pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 levels in lung tissues and serum, and more importantly ameliorated burn-induced ALI by suppressing the toll-like receptor 4/nuclear factor kappa-light-chain-enhancer of activated B cells (TLR4/NF-κB) pathway [88]. This evidence concerns the gene TLR4 and acute respiratory distress syndrome.