The Correlation Of Expression Of PPAR-γ In Pulmonary Vascular And Remodeling Of Pulmonary Vascular Induced By Cigarette Smoke Exposure In Rats

Background Pulmonary vascular remolding is the pathology foundation of many respiratory system diseases such as chronic obstructive pulmonary disease and pulmonary hypertension. More and more studies revealed that smoking has been implicated in direct actions at the pulmonary vascular. Available data have shown that Peroxisome Proliferators-activated Receptor γ(PPAR-γ) is expressed ubiquitously including in endothelial cells (ECs), vascular smooth muscle cells (VSMCs) and monocytes/macrophages, and stimulation by agonists has anti-inflammatory, anti-proliferation and promote-apoptosis that would be expected to be beneficial in vascular disorders. However, available data has focused on the effects of smoking exposure on the expression of PPAR-γ in the vascular cells in cardiovascular disorders, including hypertension and atherosclerosis, or in airways cells of respiratory system diseases. But the expression variation of PPAR-γ in pulmonary vasculature in rats after cigarette smoke exposure and its role in pulmonary vascular remodeling have been few reported.Objective With rat model after different-time cigarette smoke exposure, to investigate the expression variation of PPAR-γ in pulmonary vasculature and its role in pulmonary vascular remodeling.Methods Thirty male SD rats were randomly divided into a control group, a smoke exposure for6weeks group, a smoke exposure for12weeks group, with10rats in each group. The ratio of pulmonary vascular wall thickness/vascular external diameter (WT%) and the ratio of pulmonary vascular wall area/total pulmonary vascular area (WA%) were measured by the image analysis system. The expression of PPAR-γ protein in pulmonary vascular of each group was detected by Immunohistochemistry.Results①WT%and WA%increased significantly in the smoke exposure for6weeks group [(45.61±2.43)%,(59.69±12.59)%] and smoke exposure for12weeks group [(54.23±6.22)%,(76.26±8.36)%] compared to those of control group [(32.89±7.65)%,(33.05±14.84)%](p<0.05, respectively). The WT%and WA%in the smoke exposure for12weeks group increased significantly compared to those of smoke exposure for6weeks group (p<0.05, respectively).②The expression of PPAR-γ protein in pulmonary vascular decreased significantly in the smoke exposure for6weeks group (0.48±0.08) and the smoke exposure for12weeks group (0.37±0.07) compared to control group (0.51±0.07)(p<0.05, respectively). The expression of PPAR-γ protein decreased in the smoke exposure for12weeks group compared to the smoke exposure for6weeks group (p<0.05).③The expression of PPAR-γ protein in pulmonary vascular was respectively negatively correlated with WT%and WA%(r=-0.715and-0.683)(p<0.05, respectively).Conclusion By down-regulating the expression of PPAR-γ protein in pulmonary vascular, cigarette smoke exposure induces the remodeling of pulmonary vascular.