Institute of Biomedical and Clinical Science, University of Exeter Medical School, Plymouth, Devon, UK.
Islets. 2013 Mar-Apr;5(2):95-105. doi: 10.4161/isl.24249. Epub 2013 Mar 1.
Pro-inflammatory cytokines are important mediators of β-cell demise in type 1 diabetes, and similar mechanisms are increasingly implicated in type 2 diabetes, where a state of chronic inflammation may persist. It is likely that the actions of anti-inflammatory cytokines are also altered in diabetes. Cytokines are released from immune cells, which may be recruited to the islets in diabetes, but they can also be produced by islet endocrine cells in response to environmental factors, including enteroviral infection. Since enteroviral infection of islet cells may influence the development of diabetes in humans, we examined the actions of two cytokines, IL-13 and IL-6, whose expression are reported to be altered in β-cells during enteroviral infection. Human and rodent islet cells were shown to express receptors for both IL-13 and IL-6, and treatment with either cytokine resulted in the rapid phosphorylation of STAT3 and STAT6. However, while β-cells were protected against a range of cytotoxic insults during exposure to IL-13, treatment with IL-6 enhanced cytotoxicity and western blotting revealed that IL-13 induced one specific isoform of phospho-STAT6 preferentially. Upon incubation with both cytokines together, the isoform of STAT6 that was upregulated by IL-13 alone was again induced, and the effects of IL-6 on β-cell viability were attenuated. Overall, the results suggest that induction of specific isoforms of STAT family transcription factors may underlie the cytoprotective actions of IL-13, and they imply that selective targeting of specific STAT-mediated signaling components could provide a means to ameliorate the loss of β-cell viability in diabetes.
促炎细胞因子是 1 型糖尿病中 β 细胞死亡的重要介质,类似的机制在 2 型糖尿病中也越来越受到关注,在 2 型糖尿病中,慢性炎症状态可能持续存在。抗炎细胞因子的作用在糖尿病中也可能发生改变。细胞因子由免疫细胞释放,这些细胞可能被招募到胰岛中,但它们也可以由胰岛内分泌细胞对环境因素(包括肠道病毒感染)产生反应而产生。由于肠道病毒感染胰岛细胞可能影响人类糖尿病的发生,我们研究了两种细胞因子白细胞介素 13(IL-13)和白细胞介素 6(IL-6)的作用,据报道它们在肠道病毒感染期间β 细胞中的表达发生改变。人类和啮齿动物胰岛细胞被证明表达 IL-13 和 IL-6 的受体,用这两种细胞因子中的任何一种处理都会导致 STAT3 和 STAT6 的快速磷酸化。然而,虽然β 细胞在暴露于 IL-13 时对一系列细胞毒性损伤有保护作用,但 IL-6 的治疗增强了细胞毒性,Western 印迹显示 IL-13 诱导了一种特定的磷酸化 STAT6 同工型。当两种细胞因子共同孵育时,IL-13 单独诱导的 STAT6 同工型再次被诱导,IL-6 对β 细胞活力的影响减弱。总的来说,结果表明,诱导 STAT 家族转录因子的特定同工型可能是 IL-13 细胞保护作用的基础,这意味着选择性靶向特定的 STAT 介导的信号传导成分可能提供一种改善糖尿病中β 细胞活力丧失的方法。