SPP1 and idiopathic pulmonary fibrosis: Some of these LPAs were positively associated with biomarkers of profibrotic macrophages (CCL17, CCL18, OPN, and YKL40) and lung epithelial damage (SPD and sRAGE) (P < 0.05). In summary, our study established the association of LPAs with IPF disease progression, further supporting the role of the LPA pathway in IPF pathobiology.