We identified three profibrotic macrophage clusters that expressed similar profibrotic related gene signatures, including SPP1, FN1, CHI3L1, MMP9, MMP7, and CCL2. High expression of CD14 in these populations supports the theory that they originated from monocytes during IPF progression (58). The gene discussed is CHI3L1; the disease is idiopathic pulmonary fibrosis.