流体切应力下IL-8对中性粒细胞的作用

Effects of IL-8 on Neutrophils under Fluid Shear Chen Huaiqing

目的 考察中性粒细胞在不同类型流场中对 IL - 8的各种响应强度变化及其相互关系。方法 采用 IL - 8和稳定剪切流或正弦振荡剪切流同时对中性粒细胞作用 1分钟后 ,用流式细胞术测定中性粒细胞 CD18,CD6 2 L表达和 F- actin含量 ;以荧光染料 Fura2 /AM标记细胞内游离钙离子 (〔Ca2 +〕i) ,用荧光分光光度计测定〔Ca2 +〕i。结果 流体切应力能较大程度地影响 IL - 8作用下中性粒细胞表面粘附分子的表达 ,CD18升高 ,CD6 2 L大幅度脱落 ,这一变化与切应力的大小、型式等没有明显的关系 ;另一方面 ,流体场中 IL - 8作用的中性粒细胞内 F-actin含量随切变率的升高而迅速下降 ,继而回升 ,在切变率达 6 0 0 s- 1 时 ,已回复到无切应力时的对照水平 ;〔Ca2 +〕i在 IL- 8和流体切应力的双重作用下先大幅下降 ,而后迅速回升到对照水平。结论 流体切应力在很大程度上影响了 IL- 8对中性粒细胞的激活作用 ,调节了中性粒细胞的反应强度。细胞内游离钙离子浓度的变化最敏感 ,变化幅度最大 ,这与其第二信使作用相符合。

Objective In order to elucidate the effect of IL 8 on neutrophils in a systematic and all round way, we introduced an important physiological environment of neutrophils, fluid flow, into this study on the changes in some responses of neutrophils to IL 8 and the inter relationship of those responses under the conditions of different patterns of flow field. Methods After using IL 8 and steady flow or sinusoidal oscillate fluid shear rate simultaneously acting on separated neutrophils for one minute, we measured the expression of CD18, CD62L and the F actin content with flow cytometry and measured the free calcium concentration inside cells (〔Ca 2+ 〕i) with the fluorescent stain Fura2/AM using the fluorescent spectrophotometer. Results It was found that flow shear stress could influence the expression of surface adherence molecule of neutrophils under the action of IL 8. CD18 surface expression increased, and CD62L shed under different flow shear rates, but no significant relationship of these changes with the intensity and pattern of shear stress was noted. On the other hand, the F actin content in neutrophils under the action of shear stress and IL 8 decreased significantly at low shear rate and then gradually increased at high shear rate (600s -1 ) to the control value (without shear). The〔Ca 2+ 〕i concentration under the action of shear stress and IL 8 decreased significantly at low shear rate followed by a quick increase at high shear rate.Conclusion The flow shear stress can influence the activation effects of IL 8 on neutrophils and regulate the magnitude of neutrophil reactions to a great extent, and among these reactions, the change of 〔Ca 2+ 〕i concentration is the most sensitive one and the greatest one. This is in consistence with its second messenger role in the signal tranduction pathway. Our results could serve as a basis on which to understand better the mechanism of inflammatory reaction wherein the neutrophils under flow condition of blood are involved.