CCL2 and pulmonary fibrosis: Although alveolar macrophages have the potential to express increased levels of CCL2 after BLM treatment, as observed in this study, the migration of macrophages to the lungs is regulated largely by CCL2 in BLM-induced pulmonary fibrosis [27], and the CCL2/chemokine (CC motif) receptor-2 (CCR2) functional pathway plays an important role in pulmonary fibrosis [28].