Inhibition of PAR2 decreased the level of MMP-12 after RSV infection. Inhibition of PAR2 by FSLLRY-NH2 treatment decreased MMP-12 expression around the bronchioles (magnification, ×100) (A) and the level of MMP-12 in BALF (B). Results are representative of two independent experiments, with a total of 5 to 7 mice/group, and all data are presented as means ± SEM. ***, P < 0.001 compared to the control group; ##, P < 0.01 compared to the RSV group; ^^, P < 0.01 compared to the control group.