The methods and assays described herein relate to the diagnosis, prognosis, and treatment of subjects with emphysema, COPD, and/or cigarette-induced lung damage. In some embodiments, the methods and assays relate to subjects with a decreased level of NLRX1 expression. In some embodiments, the methods and assays relate to the administration of an agonist of NLRX1 and/or an inhibitor of MAVS.