MPO and acute respiratory distress syndrome: The levels of MDA, TNF-α, and IL-1β as well as the activity of MPO of lung tissues were significantly decreased in the ALI + HSS (iv) and ALI + HSS (ip) groups compared with the ALI group (P < 0.05), and all of these measurements were lower in the ALI + HSS (ip) group than in the ALI + HSS (iv) group (P < 0.05) (Fig. 2).