MMP2 and acute respiratory distress syndrome: The levels of RAGE, TGF-β1, MMP2, and MMP9 in the ARDS+SIS3 group were 19.34 ± 1.74, 63.10 ± 1.89, 57.90 ± 4.97, and 81.78 ± 4.97% lower than those in the ARDS group, respectively.