Effects of leptin on hypoxia-induced apoptosis in cultured alveolar typeⅡ cells of fetal rat and its mechanism / 中国病理生理杂志

ABSTRACT

AIM: To investigate the effects of leptin (LEP) on the alveolar type Ⅱ cells(AECⅡ) apoptosis induced by Na2S2O4 and explore the molecular mechanisms. METHODS: Primary AECⅡ culture was prepared according to a specific immunosorption procedure with slight modification and the cells were identified by transmission electron microscope and immunocytochemistry. AECⅡ damage was induced by 5 mmol/L Na2S2O4. LEP group cells were treated with LEP at concentrations from 100 ?g/L to 1 600 ?g/L. The cell survival rate was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Cell cycle and apoptosis were analyzed by flow cytometry and the level of caspase-3 was measured by Western blotting. RESULTS: Highly purified AECⅡ, obtained by the method of modified immunosorption, were identified with the positive expression of SP-A and intracellular lamellarbodies were found under electron micrography. The cells, exposed to 5 mmol/L Na2S2O4, showed characteristic changes of apoptosis and activation of caspase 3. These damages were relieved by the treatment of LEP (100-1 600 ?g/L), with survival increasing, apoptosis peak decreasing, cell morphology restoring and caspase 3 activation inhibiting.CONCLUSION: Leptin prevents AECⅡ from apoptosis induced by Na2S2O4 or hypoxia. The potential mechanism of its action may be related to promoting cell cycle from G1 phase to S phase and inhibiting the activating of caspase 3.