MMP1 and pulmonary emphysema: Because MMP-1 has been linked to both nonmalignant and malignant respiratory disorders, results presented here increase our understanding of how airborne DEPs can injure bronchial epithelia, sensitize airway sensory nerve afferents, and thus damage human airways and lungs in a context of several highly relevant respiratory disorders e.g., emphysema, COPD, chronic asthma, lung tuberculosis, and bronchial carcinoma (Kim et al. 2004; Mercer et al. 2004; Rutter et al. 1998; Torres-Duque et al. 2008).