Down-regulation of SMP-30 and its effects on the Fas-mediated apoptosis in the lung tissues after acute PE

AIM: To study the expression changes of senescence marker protein-30 (SMP-30) in the lung tissues of rat acute pulmonary embolism (PE) model and its effects on the Fas-mediated apoptosis. METHODS: A rat acute PE model was constructed. The samples of bronchoalveolar lavage fluid (BALF) and lung tissues were collected successively at different time points of 1 h, 8 h, 24 h and 48 h.The normal rats were used as control. The mRNA level changes of SMP-30 were identified by semi-quantitative RT-PCR. The changes of SMP-30 protein were validated by Western blotting. The immunohistochemical method was employed to study the distribution and expression changes of SMP-30 in the lung tissues and the expression of IL-8 in alveolar macrophages after PE. The apoptotic cells in lung tissue section were identified by the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) method. BALF sFasL levels were measured with an enzyme-linked immunosorbent assay (ELISA) system. RESULTS: At different time points, the mRNA levels and the protein levels of SMP-30 decreased in the lung tissues of rat acute PE models, obviously at 24 and 48 h. The immunohistochemical study indicated that SMP-30 was mainly expressed in the bronchial epithelium and the lung alveolar epithelium, and was down-regulated obviously after PE. The apoptotic cells were observed in the lung tissues after acute PE and at the same time the BALF concentrations of sFasL and the expression of IL-8 in alveolar macrophages increased obviously compared with controls. CONCLUSION: The expression of SMP-30 is down-regulated after acute PE, indicating some relationships with the activation of Fas-FasL system in the lung tissues.