糖基化终末产物上调人胰岛微血管内皮细胞黏附分子的表达和白细胞黏附

Increased adhesion molecules and leukocytes adhesion in human islet endothelial cells by advanced glycation end products

目的 研究糖基化终末产物（AGEs）对人胰岛微血管内皮细胞（HIMVEC）黏附分子表达和白细胞黏附的影响.方法 HIMVEC细胞在200 mg/L的AGEs刺激后,用细胞基础的酶联免疫吸附法（ELISA）和Western blotting法检测细胞表面黏附分子的表达;并与BCECF标记的白细胞共培养检测与白细胞的黏附能力.采用实时荧光定量聚合酶链反应（RT-PCR）和Western blotting分别检测HIMVEC细胞上AGEs受体（RAGE）、蛋白激酶Cβ（PKC β）和蛋白激酶A（PKA）的mRNA表达情况.随后给予PKC β抑制剂LY333531或PKA激活剂8-Br-cAMP,观察对HIMVEC黏附分子表达的影响及和白细胞黏附的影响.两组间比较采用t检验进行分析.结果 与对照组相比,AGEs处理后HIMVEC表达P选择素、E选择素和血管细胞黏附分子1（VCAM-1）均上调（分别为1.10 ±0.13比0.64±0.14,0.83 ±0.06比0.47 ±0.05,0.87 ±0.09比0.43±0.07,t =4.93、9.40、7.61,均P＜0.05）,并且与白细胞的黏附较对照组明显增加（54 ±4比23 ±3,t=12.69,P＜0.05）.与AGEs组比较,RAGE抗体组P选择素、E选择素和VCAM-1的表达明显降低,组间差异具有统计学意义（t=5.69、6.89、5.43,均P＜0.05）.RAGE抗体组白细胞黏附明显少于AGEs组（54±4比31 ±4,t=8.22,P＜0.05）.与对照组相比,AGEs处理HIMVEC 4 h和18h,在mRNA水平和蛋白质水平均检测到RAGE和PKCβ的表达上调,但PKA的表达下调（t=10.94、7.76、21.82、5.85、10.96、11.47,均P＜0.05）.与AGEs组相比,在AGEs处理时给予PKCβ抑制剂LY333531或PKA激活剂8-Br-cAMP,均可降低HIMVEC上P选择素、E选择素和VCAM-1的表达水平（=7.60、6.60、6.25、11.58、4.08、3.47,均P＜0.05）,并减少白细胞的黏附（t=7.67、8.89,均P＜0.05）.结论 AGEs通过RAGE受体上调PKCβ和下调PKA增加HIMVEC上黏附分子的表达,促进白细胞的黏附,可能是糖尿病状态下胰岛中白细胞浸润的机制之一.

Objective To investigate the effect of advanced glycation end products （AGEs） on adhesion molecules expression and leukocyte adhesion on human islet microvascular endothelial cells （HIMVEC）,and the related mechanisms.Methods HIMVEC was treated with AGEs （final concentration 200 mg/L）.Cell-based enzyme-linked immunosorbent assay （ELISA） and western blotting were used to detect adhesion molecules level of HIMVEC; the leukocyte-HIMVEC adhesion was evaluated after BCECF-labeled human leukocytes incubated with HIMVEC.The expression levels of receptor of AGEs （RAGE）,protein kinase C β （PKCβ） and protein kinase A （PKA） were detected by real-time PCR and Western blotting.The adhesion molecules expression and leukocyte adhesion were evaluated after cells treated with PKCβ inhibitor （LY333531） or PKA activator （8-Br-cAMP）.t-test were used to compare the difference between groups for statistical analysis.Results Compared to control group,P-selectin,E-selectin and Vascular cell adhesion molecule-1 （VCAM-1） were all up-regulated on HIMVEC by AGEs treatment （1.1 ± 0.13 vs 0.64 ±0.14,0.83 ±0.06 vs 0.47 ±0.05,0.87 ±0.09 vs 0.43 ±0.07,t =4.93,9.40,7.61,all P 〈0.05）,and leukocytes adhesion was increased in AGEs group than control （54 ± 4 vs 23 ± 3,t =12.69,P 〈0.05）.Compared to AGEs group,the expression levels of P-selectin,E-selectin and VCAM-1 were decreased by pre-treated with anti-RAGE antibody （t =5.69,6.89,5.43,all P 〈 0.05）,and leukocyte adhesion was also inhibited by RAGE antibody （54 ± 4 vs 31 ± 4,t =8.22,P 〈 0.05）.Compared to control group,after treated with AGEs for 4 h or 18 h,the mRNA and protein level of RAGE and PKCβ was up-regulated,but PKA was down-regulated （t =10.94,7.76,21.82,5.85,10.96,11.47,all P 〈 0.05）.Compared to AGEs group,PKCβ inhibitor （LY333531） or PKA activator （8-Br-cAMP） can down-regulate the expression of P-selectin,E-selectin and VCAM-1 （t =7.60,6.60,6.25,11.58,4.08,3.47,all P 〈 0.05）.And leukocyte adhesion was also reduced in LY333531 or 8-Br-cAMP group than AGEs group （t =7.67,8.89,both P 〈 0.05）.Conclusion AGEs increased adhesion molecules expression and leukocyte adhesion on HIMVEC by up-regulating PKCB and down-regulating PKA,which might be one reason for leukocyte infiltration in islets of type 2 diabetes.