CCL2 and idiopathic pulmonary fibrosis: In addition, according to our scRNA-seq results, compared with that in healthy donors, CCL2 expression was upregulated in these 3 cell types (alveolar epithelial type 2 cell, M2 macrophage and fibroblast), suggesting that fatty acid metabolism plays a role in the pathogenesis of these 3 cell types in IPF patients.