CCL2 and infection: In a previous study, we observed that transgenic mice overexpressing human CC chemokine ligand 2 (hCCL2) under control of the surfactant protein C promoter in type II alveolar epithelial cells (CCL2 Tg mice) responded to infectious challenge with Streptococcus pneumoniae (S. pneumoniae) with profound OP-like lesions involving the peripheral bronchioles and alveoli, particularly in the later resolving phase of bacterial pneumonia (day 7 post-infection), therefore recapitulating OP manifestations morphologically comparable to those seen in human patients [9].