To address these important questions given the roles of collagen in lung structure and function, we used Lyve1wt/cre; Csf1rflox/flox mice with specific depletion of Lyve-1+ macrophages and assessed the content, types and organization of collagen in lung compartments at steady state and after chronic exposure to cigarette smoke (CS) to identify a role for pulmonary collagen remodelling in protection against emphysema and loss of airway function in COPD. The gene discussed is LYVE1; the disease is pulmonary emphysema.