Prolonged exposure to free fatty acids has cytostatic and pro-apoptotic effects on human pancreatic islets -: Evidence that β-cell death is caspase mediated, partially dependent on ceramide pathway, and Bcl-2 regulated
Prolonged exposure to free fatty acids has cytostatic and pro-apoptotic effects on human pancreatic islets -: Evidence that β-cell death is caspase mediated, partially dependent on ceramide pathway, and Bcl-2 regulated
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DOI：
10.2337/diabetes.51.5.1437
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发表时间：
2002-05-01
期刊：
影响因子：
7.7
通讯作者：
Marchetti, P
中科院分区：
文献类型：
--
作者：
Lupi, R;Dotta, F;Marchetti, P
为了更好地理解人类β细胞中的脂毒性现象，我们评估了用1.0或2.0 mmol/l游离脂肪酸（FFA）（油酸与棕榈酸的比例为2：1）预培养48 h对分离的人类胰岛功能和存活的影响，并研究了一些可能的机制。与对照组相比，在FFA浓度增加的预培养胰岛中，甘油三酯含量显着增加，胰岛素含量和葡萄糖刺激的胰岛素释放显着减少。这些变化伴随着葡萄糖利用和氧化的显着减少。通过细胞死亡检测技术，观察到暴露于FFA诱导死亡细胞的量显著增加。电子显微镜检查显示β细胞的参与，与凋亡现象的存在相容的形态学外观。FFA诱导的胰岛细胞死亡被阻断上游半胱天冬酶的抑制和部分防止神经酰胺合成或丝氨酸蛋白酶活性的抑制，而抑制一氧化氮的合成没有影响。RT-PCR结果显示，FFA组胰岛中iNOS和Bax mRNA表达无明显变化，Bcl-2 mRNA表达明显下降。因此，长期暴露于FFA对人胰腺β细胞具有细胞生长抑制和促凋亡作用。细胞生长抑制作用可能是由于FFA诱导的胰岛内葡萄糖代谢的减少，并且促凋亡作用主要是caspase介导的，部分依赖于神经酰胺途径，并且可能是Bcl-2调节的。
In an effort to better understand the phenomenon of lipotoxicity in human beta-cells, we evaluated the effects of 48-h preculture with 1.0 or 2.0 mmol/l free fatty acid (FFA) (2:1 oleate to palmitate) on the function and survival of isolated human islets and investigated some of the possible mechanisms. Compared with control islets, triglyceride content was significantly increased and insulin content and glucose-stimulated insulin release were significantly reduced in islets precultured with increased FFA concentrations. These changes were accompanied by a significant reduction of glucose utilization and oxidation. By cell death detection techniques, it was observed that exposure to FFAs induced a significant increase of the amount of dead cells. Electron microscopy showed the involvement of beta-cells, with morphological appearance compatible with the presence of apoptotic phenomena. FFA-induced islet cell death was blocked by inhibition of upstream caspases and partially prevented by inhibiton of ceramide synthesis or serine protease activity, whereas inhibition of nitric oxide synthesis had no effect. RTPCR studies revealed no major change of iNOS and Bax mRNA expression and a marked decrease of Bcl-2 mRNA expression in the islets cultured with FFA. Thus, prolonged exposure to FFAs has cytostatic and proapoptotic effects on human pancreatic beta-cells. The cytostatic action is likely to be due to the FFA-induced reduction of intraislet glucose metabolism, and the proapoptotic effects are mostly caspase mediated, partially dependent on ceramide pathway, and possibly Bcl-2 regulated.