Objective: To investigate effect of oxidized low-density lipoprotein (ox-LDL) on memory CD8+ T cell subpopulation differentiation in mice with autoimmune diabetes.
Methods: Cultured splenic CD8+ T cells from pre-diabetic NOD mice isolated with magnetic beads were treated with 30 µg/mL ox-LDL and 10 U/mL interleukin-2 (IL-2) for 24 h and the control cells were treated with IL-2 only. Flow cytometry was used to determine the percentage of splenic CD8+IFN-γ+ T cells, expressions of CD8, CD44 and CD62L on the T cells, and the activation of T cell factor-1 (TCF-1) and STAT-3. The CD127+ memory T cells were purified and transplanted into the pre-diabetic NOD mice via the tail vein, and the blood glucose was recorded weekly and survival time of the mice was monitored.
Results: Treatment with ox-LDL significantly reduced islet β cell-specific cytotoxic CD8+T cells as compared with the control group [(0.7∓0.03)% vs (2.7∓0.14)%, P<0.01]. The percentage of effector memory CD8+T cells (Tem) in the total memory CD8+T cells was reduced [(10.3∓0.71)% vs (30.3∓1.36)%, P<0.01] and that of stem cell-like memory T cells was significantly increased [(72.3∓3.8)% vs (55.1∓2.61)%, P<0.05] following ox-LDL treatment, which also resulted in significantly decreased activation of TCF-1 [(14.5∓0.82)% vs (34.2∓1.23)%, P<0.01] and pSTAT-3 [(3.3∓0.12)% vs (22.1∓1.1)%, P<0.01]. Transplantation of ox-LDL-treated memory T cells in pre-diabetic NOD mice obviously inhibited the increase of blood glucose and prolonged the survival time of the mice (P<0.05).
Conclusion: Ox-LDL decreases the activation of transcriptional factors TCF-1 and phosphorylation of STAT-3, inhibits the formation of effector memory CD8+ T cells with long-term cytotoxicity, but promote the generation of stem cell-like memory CD8+ T cells, which result in suppression of islet β cell-specific effector cytotoxic CD8+ T cell differentiation to lessen autoimmune injury to the islet β cells.
目的: 探讨氧化低密度脂蛋白（ox-LDL）对CD8+记忆性T细胞亚群分化的影响及其机制。
方法: 将雌性10周龄未发生糖尿病NOD小鼠随机分为2组（n=5）：ox-LDL组及对照组。断颈处死各组小鼠磁珠分离脾脏CD8+T细胞体外培养（IL-2），ox-LDL组加入ox-LDL 30 μg/mL体外刺激24 h，ox-LDL未处理组作为对照组。24 h后分离细胞。体外实验利用流式细胞仪检测各组以下指标：胞内CD8+IFN-γ+确定胰岛β细胞特异性杀伤性CD8+T细胞的比例；细胞表面分子CD8、CD44、CD62L确定CD8+记忆性T细胞的不同亚群分化；T细胞相关转录因子TCF-1及STAT-3的活化确定关键性转录因子的作用。体内实验中，将各组CD8+记忆性T细胞通过尾静脉注射的方法移植给未发病NOD小鼠，同时设立未移植的模型对照组，每5 d检测血糖1次，监测小鼠的血糖改变及生存率。
结果: 相比对照组，ox-LDL（30 μg/mL）作用24 h后，胰岛β细胞特异性杀伤性CD8+T细胞活化减少（[ 0.7±0.03）% vs（2.7±0.14）%，P < 0.01]，记忆性T细胞中的效应记忆性T细胞形成数目减少（[ 10.3±0.71）% vs（30.3±1.36）%，P < 0.01]，干细胞样记忆性T细胞增加（[ 72.3±3.8）% vs（55.1±2.61）%，P < 0.05]。T细胞转录因子TCF-1及p-STAT-3活化的也受到抑制[TCF-1：（14.5±0.82）% vs（34.2±1.23）%，磷酸化STAT-3：（3.3±0.12）% vs（22.1±1.1）%，P < 0.01]。T细胞移植给未发病NOD小鼠后，ox-LDL处理组小鼠血糖升高明显低于对照组（P < 0.05），且生存率提高（P < 0.05）。
结论: ox-LDL干扰记忆性CD8+T细胞核转录因子TCF-1活化及STAT-3的磷酸化，抑制长效杀伤作用的效应性和记忆性CD8+T细胞形成，诱导干细胞样记忆性CD8+T细胞形成，从而阻止胰岛β细胞自身免疫损伤及Ⅱ型糖尿病的发生