CCR2 and acute respiratory distress syndrome: Before studying the role of CCR2 in the model of LPS-induced ARDS, we evaluated the levels of its ligand, CCL2, in the bronchoalveolar lavage fluid (BALF) of CCR2+/+ and CCR2−/− mice and observed increased levels of this chemokine mainly on days 2 and 3 after the insult, but at remarkedly higher levels in CCR2−/− mice when compared to CCR2+/+ mice (Figure 1A).