Agonistic induction of PPAR gamma reverses cigarette smoke-induced emphysema

作者：Shan Ming; You Ran; Yuan Xiaoyi; Frazier Michael V; Porter Paul; Seryshev Alexander; Hong Jeong Soo; Song Li Zhen; Zhang Yiqun; Hilsenbeck Susan; Whitehead Lawrence; Zarinkamar Nazanin; Perusich Sarah; Corry David B; Kheradmand Farrah^*

来源：Journal of Clinical Investigation, 2014, 124(3): 1371-1381.

DOI：10.1172/JCI70587

The development of emphysema in humans and mice exposed to cigarette smoke is promoted by activation of an adaptive immune response. Lung myeloid dendritic cells (mDCs) derived from cigarette smokers activate autoreactive Th1 and Th17 cells. mDC-dependent activation of T cell subsets requires expression of the SPP1 gene, which encodes osteopontin (OPN), a pleiotropic cytokine implicated in autoimmune responses. The upstream molecular events that promote SPP1 expression and activate mDCs in response to smoke remain unknown. Here, we show that peroxisome proliferator-activated receptor gamma (PPARG/Pparg) expression was downregulated in mDCs of smokers with emphysema and mice exposed to chronic smoke. Conditional knockout of PPAR gamma in APCs using Cd11c-Cre Pparg(flox/flox) mice led to spontaneous lung inflammation and emphysema that resembled the phenotype of smoke-exposed mice. The inflammatory phenotype of Cd11c-Cre Pparg(flox/flox) mice required OPN, suggesting an antiinflammatory mechanism in which PPARy negatively regulates Spp1 expression in the lung. A 2-month treatment with a PPAR gamma agonist reversed emphysema in WT mice despite continual smoke exposure. Furthermore, endogenous PPAR gamma agonists were reduced in the plasma of smokers with emphysema. These findings reveal a proinflammatory pathway, in which reduced PPAR gamma activity promotes emphysema, and suggest that targeting this pathway in smokers could prevent and reverse emphysema.

• 出版日期2014-3