Figure 5.

Mmp10^–/– mice are resistant to cigarette smoke-induced emphysema. (A) Representative H&E lung sections of Mmp10^–/– and wild-type animals exposed to 6 months of chronic cigarette smoke demonstrated extensive injury in wild types with significant loss of acinar and small airway structures (top row). In contrast, Mmp10-null mice were substantially less susceptible to smoke-induced emphysema (bottom row). Slides are ordered according to severity of lung injury in each genotype. (B) Morphometric analysis of airspaces using the mean linear intercept method confirmed the protective phenotype observed in Mmp10^–/– mice (n = 10 for smoke exposed Mmp10^–/– mice, n = 9 for all other groups). (C) Wild-type mice exposed to chronic cigarette smoke have significantly increased expression of the pro-inflammatory cytokine Il1b as well as Mmp10 in their lungs, whereas emphysema-resistant Mmp10^–/– animals do not (n = 8 per group). All P-values based on two-tailed Student's t-test; NS, not significant.