Role of melatonin as an SIRT1 enhancer in chronic obstructive pulmonary disease induced by cigarette smoke.

Background Melatonin has various biological activities that improve the health of an individual. We evaluated the effects of melatonin on inflammatory response in chronic obstructive pulmonary disease (COPD), focusing on the regulation of SIRT1 expression. Methods To investigate the effect of melatonin, we used cigarette smoke (CS)-induced COPD mouse model and CS condensate (CSC)-stimulated J774 macrophage cells. Results CSC-stimulated J774 macrophages exhibited increased p65 acetylation with a reduction in SIRT1 expression. However, melatonin induced the enhancement of SIRT1 expression, which eventually decreased p65 acetylation in CSC-stimulated J774 cells. Melatonin-treated mice exhibited an enhancement in SIRT1 expression with the reduction in p65 acetylation, which decreased the level of inflammatory mediators induced by CS. Additionally, SIRT1 inhibitor treatment increased the level of inflammatory mediators, which was accompanied by an increase in p65 acetylation. However, cotreatment with melatonin and an SIRT1 inhibitor reduced the level of inflammatory mediators compared with that by treatment with the SIRT1 inhibitor alone, which was accompanied by elevation in SIRT1 expression and reduction in p65 acetylation. Conclusions Overall, the results indicated that melatonin has therapeutic effects against COPD, owing to its property to enhance SIRT1 expression.