SIRT1 and pulmonary fibrosis: For instance cigarette smoking downregulates SIRT1, leading to dysregulation of lipid metabolism and activation of lung fibroblasts, thereby promoting the development of idiopathic pulmonary fibrosis, SIRT1 activator SRT1720 counteracted the effect of CS on NOX4, SOD2, PPARα and CPT1a in vivo [58].