Consistent with our results, a prior study implicated MMP8 as a differentiating protein in a 5-protein classifier (MMP1, MMP7, MMP8, IGFBP-1, TNFRS1A) of IPF status, although the classification model did not select MMP9 and did not consider TIMP1 [11]. This evidence concerns the gene MMP9 and idiopathic pulmonary fibrosis.