MMP1 and pulmonary emphysema: Especially MMP-9 (but also to a lesser extent MMP-1,-10 and -12) have been implicated in the underlying disease mechanism of obstruction of small airways, development of emphysema, mucus hypersecretion and low grade inflammation assessed at both the local, sputum and broncho-alveolar lavage (BAL), and systemic level [1, 3–7].