PPARGC1A and pulmonary emphysema: Sirtuin 1 (SIRT1) is a powerful deacetylase that has been shown to activate PGC-1α to drive mitochondrial biogenesis [16], and SRT1720, the activator of SIRT1, is an effective SIRT1 agonist that enhances PGC-1α activation [17–19]. In previous reports, SRT1720 alleviated lung injury and improved the lung function in rat with emphysema caused by cigarette smoke through protecting against the apoptosis of type II alveolar epithelial cells [20].