白细胞介素-17对中性粒细胞凋亡的影响

Effect of Interleukin-17 on neutrophil apoptosis

目的:研究白细胞介素(interleukin,IL)17对中性粒细胞凋亡的影响并探讨其可能的内在机制。方法:分离培养健康人外周血中性粒细胞,分别加入IL17、热灭活IL17(XIL17)和地塞米松,并设立对照组。通过形态学观察和DNA片段化的检测分析凋亡情况;利用免疫细胞化学方法检测中性粒细胞Bax蛋白的表达。结果:培养中对照组中性粒细胞呈现出凋亡极具特征性的形态学改变;随时间延长,凋亡指数(apoptosisindex,AI)呈上升趋势,0h为(1.54±0.08)%,12h为(11.48±1.80)%(与0h比较,P<0.05),24h为(34.19±1.92)%(与0h比较,P<0.01)。在50μg/L质量浓度时IL17促进中性粒细胞凋亡,0,12,24h的AI分别为(1.43±0.17)%(与对照组0h比较,P>0.05),(20.47±6.22)%(与对照组12h比较,P<0.01)和(40.74±3.48)%(与对照组24h比较,P<0.05);而IL17在质量浓度为5μg/L和0.5μg/L浓度时可抑制凋亡,24h的AI分别为(14.24±4.26)%和(19.86±4.39)%,与对照组24h比较,P均<0.01。50μg/LXIL17组24h的AI为(33.22±1.61)%(与对照组24h比较,P>0.05)。中性粒细胞凋亡的同时伴有DNA的片段化。免疫化学染色显示同期中性粒细胞Bax蛋白表达量与AI呈强正相关(r=0.932,P<0.01)。结论:体外IL17对中性粒细胞的凋亡有调节作用,在较高浓度下加速凋亡,在较低浓度下延缓凋亡。IL17对Bax蛋白表达的调控可能是其内在机制之一。

Objective： To study the effect of Interleukin（IL）-17 on neutrophil apoptosis and try to explain the possible mechanism involved. Methods： Neutrophils isolated from healthy donors were incubated in enriched RPMI 1640 cell culture medium at 37℃ in 5% carbon dioxide. Subgroups were incubated with IL-17, heat-denatured IL-17 （X-IL-17）, dexamethasone （DEX）, or buffer alone. Apoptosis was assessed by morphologic changes, by detecting DNA strand breaks. Production of proapoptotic protein Bax by neutrophils was evaluated by immunocytochemistry. Results： At the time of neutrophil incubation, neutrophils in the control subsets exhibited morphologic evidence of apoptosis. A steady rise in apoptosis index （AI） was noted, with （ 1.54±0.08 ） % for 0 h, （ 11.48 ± 1.80 ） % （ compared with 0 h, P 〈 0.05 ） for 12 h and （34.19 ±1.92） % （ compared with 0 h, P 〈 0.01 ） for 24 h, respectively. IL-17 at concentration of 50μg/L resulted in increased AI of neutrophils, with （ 1.43 ± 0.17 ） % （ compared with control 0 h, P 〉 0.05 ） for 0 h, （20.47±6.22 ） % （ compared with control 12 h, P 〈 0.01 ） for 12 h and （40.74± 3.48）% （compared with control 24 h, P 〈0.05 ） for 24 h, respectively. While at concentrations of 5μg/L and 0.5μg/L, IL-17 resulted in decreased AI, with （ 14.24±4. 26 ） % （ compared with control 24 h, P 〈 0.01 ） for 24 h, and （ 19.86±4.39 ） % （ compared with control 24 h, P 〈0.01 ） for 24 h, respectively. AI of neutrophils treated with X-IL-17 at concentration of 50 ng/ml for 24 h was （33.22 ±1.61 ） % （ compared with control 24 h, P 〉 0.05 ）. Neutrophils apoptosis was accompanied by DNA fragmentation. In all groups, the increasing of Bax immunoreactivity was strongly related with more apoptotic neutrophils （ r= 0. 932, P 〈 0.01 ）. Conclusion： In vitro, IL-17 modulates apoptosis of neutrophils. At higher concentrations, it accelerates neutrophils apoptosis. At lower concentrations, it delays neutrophils apoptosis. Modulation of the expression of Bax by IL-17 may be one of the possibleinner mechanisms.