MRC1 and acute respiratory distress syndrome: Conversely, the administration of TTM significantly reduced the numbers of pulmonary CD68+ (P < 0.05) and CD86+ macrophages (P < 0.05) in the experimental MA-ALI/ARDS mice relative to those in the Pb group, while dramatically elevating the number of pulmonary CD206+ macrophages (P < 0.01).