α1-Antitrypsin Determines the Pattern of Emphysema and Function in Tobacco Smoke–exposed Mice

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Abstract
Cigarette smoking in humans is associated with various patterns of emphysema and functional consequences. We tested the hypothesis that variations in α1-antitrypsin expression modulate the pattern of emphysema and functional consequences in cigarette smoke–exposed mice. We compared the effects of up to 6 months of cigarette smoke exposure in C57BL/6J (C57) mice and in low-α1-antitrypsin, C57BL/6J pa+/pa+ (pallid) mice. At the end of the experiment, we determined lung mechanical properties, the extent (mean linear intercept) and type of emphysema, and the cellular inflammatory response. After 4 months of cigarette smoking, pallid smoking mice, but not C57 smoking mice, had a significant increase in mean linear intercept. After 6 months of smoke exposure, C57 smoking mice and pallid smoking mice had similar degrees of emphysema. The pattern of emphysema in pallid smoking mice was more diffuse than in C57 smoking mice, affecting all airspaces. Pallid mice, but not C57 mice, developed a T cell inflammation in the alveolar wall after 6 months of smoking (p < 0.01). Although lung compliance was not changed in C57 smoking mice after smoke exposure, it increased significantly in pallid smoking mice over the 6 months of exposure (p < 0.0082). In summary, cigarette smoking induces emphysema in C57 and pallid mice, but the emphysema, inflammatory infiltrate, and resulting physiologic abnormalities were substantially different in the two strains, with the C57 and pallid mice exhibiting features similar to centrilobular and panlobular emphysema, respectively.