While the ligand(s) responsible for TLR4 activation remain poorly defined in IPF, it will likely be a scenario where a combination of Pathogen-Associated Molecular Patterns (PAMPs) and Damage-Associated Molecular Patterns (DAMPs) will be required for the increased TLR4-mediated signaling [67,72,73,74,75,76]. This evidence concerns the gene TLR4 and idiopathic pulmonary fibrosis.