白细胞介素-17对中性粒细胞凋亡的影响

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IL-17、热灭活IL-17(X-IL-17)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(apoptosis index,AI)呈上升趋势,0 h为(1.54±0.08)%,12 h为(11.48±1.80)%(与0 h比较,P＜0.05),24 h为(34.19±1.92)%(与0 h比较,P＜0.01).在50μg/L质量浓度时IL-17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0 h比较,P＞0.05),(20.47±6.22)%(与对照组12 h比较,P＜0.01)和(40.74±3.48)%(与对照组24 h比较,P＜0.05);而IL-17在质量浓度为5μg/L和0.5μg/L浓度时可抑制凋亡,24 h的AI分别为(14.24±4.26)%和(19.86±4.39)%,与对照组24 h比较,P均＜0.01.50μg/L X-IL-17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IL-17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.IL-17对Bax蛋白表达的调控可能是其内在机制之一.

Effect of Interleukin-17 on neutrophil apoptosis

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 degrees C 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 50 microg/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 5 mug/L and 0.5 microg/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 possible inner mechanisms.