Fig. 2.
Sections of mouse lung tissue from X0/HNE and SP-B1-25-X2/HNE groups after 4 wk. (A and B) Animals given the potent small molecule inhibitor X0 with HNE developed large airspaces characteristic of emphysema (Fig. 1 C and D). The inhibitor, although having a Ki < 12 nM in vitro, had no efficacy in vivo. (C and D) When the small molecule inhibitor X2 was covalently linked to a surfactant peptide fragment to form the construct SP-B1-25-X2, it lost 50-fold potency in vitro but provided complete protection in vivo even after 4 wk.