流体切应力强度对内皮细胞IL-8基因表达的影响

Force-dependent Effects of Interleukin-8 Gene Expression in Endothelial Cells Exposed on Fluid Shear Stress

内皮细胞位于血流与血管壁之间 ,内皮细胞调控的机械力相关反应已成为正常血管反应的一部分。切应力在调节内皮细胞功能上具有重要作用。流体切应力可以直接调节内皮细胞基因的表达 ,其中包括诱导内皮细胞表达 IL- 8,而且 IL- 8的表达量与切应力作用时间有关。为阐明内皮细胞 IL- 8基因的表达除了与切应力的作用时间有关外还与切应力的强度有关 ,我们用不同强度的流体切应力 (2 .2 3、4 .2 0、6 .0 8、8.19、9.6 7、12 .15、14 .4 0、16 .87、19.2 9dyne/ cm2 )处理培养的人脐静脉内皮细胞 ,然后采用定量 RT- PCR的方法检测内皮细胞 IL- 8基因的表达情况。结果显示 :未用切应力处理的内皮细胞没有 IL- 8基因的表达 ;切应力处理内皮细胞后 ,低切应力 (2 .2 3dyne/ cm2 )时 IL - 8m RNA表达量明显增加为高切应力 (19.2 9dyne/ cm2 )时 IL - 8m RNA表达量的约 6 8(作用 1h)或 5 2倍 (作用 2 h)。 IL- 8m RNA的表达量与内皮细胞所施加的切应力强度呈反变关系 ;直线回归方程 :1h时为 y=7.5 7- 0 .11x,相关系数 r=0 .97;2 h时为 y=7.92 - 0 .10 x,相关系数 r=0 .96。式中 :y为切应力作用下内皮细胞 IL- 8m RNA的表达量 (拷贝数的对数值 ) ;x为施加于内皮细胞的切应力强度 (dyne/ cm2 )。

Fluid shear stress plays an important role in many physiological and pathophysiological processes of the cardiovascular system. Previous studies have identified the exposure of vascular endothelial cells to fluid mechanical forces can modulate the expression of many genes, including IL-8 gene expression, and IL-8 expression induced by fluid shear stress was time-dependent. To investigate the role of intensity of fluid shear stress on IL-8 expression in human umbilical vein endothelial cells (HUVECs), we had HUVECS exposed to shear stress 2.23, 4.20, 6.08, 8.19, 9.67, 12.15, 14.40, 16.87, and 19.29 dyne/cm2 respectively and employed quantitative reversal transcription-polymerize chain reaction (qRT-PCR) to assay the expression of IL-8 mRNA. The results show that IL-8 mRNA did not express in HUVECs untreated with fluid shear stress. The IL-8 mRNA expression by shear stress was force intensity-dependent. After HUVECS exposed to low fluid shear stress (2.23 dyne/cm2) for 1 h or 2 h, IL-8 mRNA expression increased near 68 or 52 times as that of HUVECs exposed to high fluid shear stress (19.29 dyne/cm2). The linear regression equations between IL-8 mRNA expression (log (copies), y) and shear stress (dyne/cm2, x) are: y=7.57-0.11x, r=0.97 (for 1 h); y=7.92-0.10x, r=0.96 (for 2 h). This in vitro study demonstrates the expression of IL-8 gene can be regulated by fluid shear stress. The low shear stress could induces much more expression of IL-8 mRNA, which plays probably an important role in the pathogenesis of inflammation and arteroatherosclerosis.