‘This improved publicity means there will still be growing numbers of significant musculoskeletal injuries, both traumatic and chronic overuse.’ Awareness and prevention can help, and Dr. DeBerardino says it’s important to recognize that adolescents are just as vunerable to overuse and traumatic joint/extremity accidental injuries as adults. At the same time, they are not ‘miniature adults’ and because their bodies are still growing, there are unique concerns in relation to orthopaedic injuries. For instance: If metal hardware needs to be surgically implanted in an area that is still growing, it could stunt a child’s growth. If an adolescent has shoulder surgery, but the tension on the repair is too limited, it can lead to a lifetime of chronic discomfort.’Everyone wants to get to the top,’ says Dr.Soto-Quiros, M.D., Ph.D., Lydiana Avila, M.D., Jessica Lasky-Su, Sc.D., Chris Stidley, Ph.D.D., Ph.D.D., Jenny Hallberg, Ph.D., Inger Kull, R.N., Ph.D., Juha Kere, M.D., Ph.D., Magnus Svartengren, M.D., Ph.D.D., Ph.D., Magnus Wickman, M.D., Ph.D., Christoph Lange, Ph.D., Dawn L. Demeo, M.D., M.P.H., Craig P. Hersh, M.D., M.P.H., Barbara J. Klanderman, Ph.D., Benjamin A. Raby, M.D., M.P.H., David Sparrow, D.Sc., Steven D. Shapiro, M.D., Edwin K. Silverman, M.D., Ph.D., Augusto A. Litonjua, M.D., M.P.H., Scott T. Weiss, M.D., and Juan C.D., Dr.P.H.: MMP12, Lung Function, and COPD in High-Risk Populations MMP-12 is produced by macrophages, the predominant cell type that patrols the lower airspaces under normal conditions and the main inflammatory cell type that is recruited with cigarette smoking.1 Mmp12 is vital for the development of emphysema in mice exposed to tobacco smoke,2 including mice with an increase of expression of interleukin-13.3 Elevated expression of MMP12 in the lower airways can result in degradation of elastin, resulting in elastin fragments that may cause a positive feedback loop, further raising macrophage recruitment in mice4 and in cultured human cells.5 In humans, a rise in MMP12 expression by a factor of nearly 9 has been noted in alveolar macrophages from smokers in comparison with those from non-smokers.6 Despite these findings, the function of MMP-12 in the advancement of emphysema in humans remains unclear.