The concept of endogenous TLR ligands amplifying host responses to inflammatory triggers is supported by our recent findings that highly purified LTA, which is an established TLR2 ligand [32], [41]–[44], induces less profound lung inflammation not only in TLR2 KO mice, but also in TLR4 KO mice [45] 47). Here, TLR4 is linked to inflammation.