高糖环境下白细胞介素1β对大鼠视网膜Mǚller细胞谷氨酰胺合成酶的影响

Effect of interleukin-1β on glutamine synthetase in rat retinal Miiller cell under high glucose condlitions

目的探讨高糖环境下白细胞介素1β（IL-1β）对视网膜Mǚller细胞谷氨酰胺合成酶的影响及其机制。方法将体外培养的大鼠Mǚller细胞随机分为对照组（5mmol／L葡萄糖）和实验组（25mmol／L葡萄糖），分别以不同浓度的IL-1β（0、0．1、1．0、5．0、10．0ng／ml）刺激24h后，采用间接免疫荧光法和免疫印迹法检测两组细胞内谷氨酰胺合成酶（GS）和即早基因c—Jun的表达变化，使用流式细胞仪Annexin V—FITC／PI双染色法测定两组细胞凋亡的情况。结果细胞免疫荧光组化法和免疫印迹法检测显示在高糖环境下就有Mǘller细胞GS表达下降、IL-1β和c—Jun表达的升高（P〈0．05）；IL-1β刺激24h后，对照组和实验组Mǚller细胞中GS的表达都随IL-1β刺激浓度升高而逐渐降低同时c—Jun的表达随IL-1β刺激浓度的增加而升高，这一结果在高糖状态下尤为明显；流式细胞仪检测显示不同浓度的IL-1β刺激24h后，两组细胞随着IL-1β浓度的增加凋亡率明显升高，在高糖环境下细胞凋亡率的增加更加明显。结论模拟糖尿病状态下，免疫相关因子IL-1β可使GS表达下降，从而影响了谷氨酸的循环，可能间接引起神经节细胞的死亡，出现早期神经视网膜功能的障碍。其可能机制为IL-1β激活了c-Jun途径而影响GS的功能。

Objective To investigate the effect of cytokine interleukin-1β （IL-1β） on the glutamine synthetase （GS） in retinal Mǚller cell under high glucose conditions and its possible mechanism. Methods Cultured Mǚiler cells were divided into the control group （5 mmol/L glucose） and experimental group （25 mmol/L glucose） randomly. After being treated with different doses of IL-1β for 24 hours, the effect of IL-1β on the expressions of GS and c-Jun in retinal Mǚller cells in the control and experimental groups was measured by western blot analysis and indirect immunofluorescence. Apoptosis of retinal Mǚller cells induced by IL-1β in the control and experimental groups was analyzed by flow cytometry after Annexin V-fluorescein isothiocyanate/Propidium idoium （Annexin V-FITC/PI ） staining. Results Under high glucose condition, increase in the expression of c-Jun and IL-1β and decrease in the expression of GS could be found by western blot analysis and immunocytochemistry （ P 〈 0. 05 ）. After being treated by IL-1β, the expression of GS was down-regulated significantly and the expression of c-Jun was up-regulated significantly in a dose-dependent manner in these two groups, especially under high glucose condition. IL-1β caused a dose-dependent increase of apoptosis of retinal Mailer cells in these two groups. Apoptosis of Mǚller cells under high glucose condition increased more significantly than that in cells cultured with 5 mmol/L glucose. Conclusions In mimiced diabetic condition, IL-1β decreases the expression of GS in retinal Mǚller cells, which may elevate the level of glutamate and cause the damage of the ganglion cells. The possible mechanism of this effect is the activation of c-Jun by IL-1β.