TREM2 and acute respiratory distress syndrome: We also found the number of TREM2-positive cells was notably decreased in the LPS-induced ALI group compared to the control group, and GSP (25, 50, and 75 mg/kg) increased the number of TREM2-positive cells, indicating that GSP treatment promoted TREM2 expression in lung macrophages of ALI mice (Fig. 4B, C).