肿瘤坏死因子-α对肝星状细胞增殖与凋亡的影响

目的:探讨肿瘤坏死因子-α(TNF-α)在肝纤维化发病中的作用。方法:采用TNF-α对体外培养的HSC进行干预, 通过流式细胞术、电镜及TUNEL等方法, 对HSC的增殖与凋亡进行研究。结果:①流式细胞术显示:TNF-α各组的G₀/G₁期细胞比率明显高于对照组, 而S期细胞比率明显低于对照组, 各组的细胞增殖指数均明显低于对照组;在凋亡方面, TNF-α各组的HSC凋亡率明显高于对照组, TNF-α各组HSC中抗凋亡基因bcl-2的表达明显低于对照组, 而促凋亡基因bax的表达明显高于对照组。②TUNEL分析显示:TNF-α(2.0μg/L)组的HSC凋亡率为18.7%±2.5%, 而对照组为5.3%±1.2%, 两者之间有显著差异。结论:TNF-α能够阻止HSC从G₀/G₁期进入S期, 从而具有抑制HSC增殖的作用;TNF-α能够降低HSC中bcl-2的表达、提高bax的表达, 这可能与其促进HSC凋亡有关。

Effects of tumor necrosis factor alpha on proliferation and apoptosis of HSCs

AIM:To explore the role of tumor necrosis factor alpha(TNF-α) in the pathogenesis of liver fibrosis.METHODS:The proliferation and apoptosis of hepatic stellate cells (HSCs) in vitro were detected with flow cytometry, electron microscopy and TUNEL.RESULTS:The flow cytometry analysis showed that the cell proliferation index (PI) in the TNF-α(0.5 μg/L, 2.0 μg/L, 8.0 μg/L) groups was evidently lower than that in the control group (P＜0.05). In the cell cycle distribution, the portion of G₀/G₁ phase in the TNF-α groups was significantly higher than that in the control group(P＜0.05), but the portion of S phase in the TNF-α groups was evidently lower than that in the control group(P＜0.05). These indicated that TNF-α interfered with HSCs entrance into S phase from G₀/G₁ phase whereupon the proliferation of HSCs was inhibited. The apoptotic rate in the TNF-α groups was evidently higher than that in the control group(P＜0.05). The gene expression of bcl-2 and bax was also detected with flow cytometry. The expression of bcl-2 in the TNF-α groups was evidently lower than that in the control group(P＜0.05), but the expression of bax in the TNF-α groups was significantly higher than that in the control group(P＜0.05). TUNEL analysis showed the apoptotic rate of HSCs in the TNF-α(2.0 μg/L) group was 18.7%±2.5% compared with 5.3%±1.2% in the control group(P＜0.05).CONCLUSIONS:TNF-α interfered with HSCs entrance into S phase from G₀/G₁ phase whereupon the proliferation of HSCs was inhibited. TNF-α down-regulated bcl-2 gene expression and up-regulated bax gene expression whereupon the apoptosis of HSCs was induced.