Peroxisome proliferator-activated receptor-γ in induced sputum is correlated with MMP-9/TIMP-1 imbalance and formation of emphysema in COPD patients

Xiao-Ming Zhou, Gang Hou, Dong-Xue Gu, Qiu-Yue Wang, Li Zhao


Background: The development of chronic obstructive pulmonary disease (COPD) is modulated by the symmetry of matrix metalloproteinases (MMPs) and the counter-acting tissue inhibitors of metalloproteinases (TIMPs). We investigated the interaction between peroxisome proliferator-activated receptor gamma (PPARγ) expression and the imbalance of MMP-9/TIMP-1 in the induced sputum of stable COPD patients.
Methods: Sixty-six stable COPD patients were enrolled and the induced sputum samples were gathered. The correlation between PPARγ and other index, including MMP-9, TIMP-1, pulmonary function and the index of emphysema—the percentage of low attenuation area (LAA%), was analyzed.
Results: PPARγ and TIMP-1 concentrations were decreased and the concentration of MMP-9 and the ratio of MMP9/TIMP1 were enhanced in the induced sputum of COPD patients, compared to the healthy controls. Among COPD patients, those with worse lung function or patients with emphysema exhibited increased MMP-9 expression with decreased TIMP-1 and PPARγ expression. Besides, the concentration of PPARγ of the induced sputum was correlated with the forced expiratory volume in one second percentage (FEV1%) positively and the expression of TIMP-1; while it was negatively correlated with the residual volume (RV), RV/total lung capacity (TLC), LAA%, and MMP-9 expression.
Conclusions: Our findings reveal the protective role of PPARγ in the maintenance of the dynamic balance of MMP-9/TIMP-1 in COPD, thus providing evidence on which to base the potential COPD treatment.