MMP9 and pulmonary emphysema: In the context that lung epithelial lining fluid (ELF) of HIV1+ smokers has increased levels of a variety of cytokines [5, 7–10] and that several cytokines mediate the activation state of AM [11, 12], we hypothesized that, in the presence of cigarette smoke, upregulation of MMP-9 is associated with increased levels of proinflammatory cytokines and that their interplay may be contributing to the early development of emphysema in HIV1+ smokers.