A connection to IPF is suggested by the finding that endogenous TLR4 ligands such as high mobility group box 1 (HMGB1) (Park et al., 2004; Li et al., 2014), tenascin-C (Midwood et al., 2009; Carey et al., 2010; Bhattacharyya et al., 2016), S100 protein (Park et al., 2004) and hyaluronan fragments (Jiang et al., 2005) are enriched in IPF BAL and lung tissues (Huebener and Schwabe, 2013). This evidence concerns the gene TLR4 and idiopathic pulmonary fibrosis.