Mudaliar Harshini, Pollock Carol, Ma Jin, Wu Huiling, Chadban Steven, Panchapakesan Usha
Renal Research Group, Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, New South Wales, Australia.
Renal Medicine Royal Prince Alfred Hospital and Collaborative Transplant Research Group, University of Sydney, Camperdown, New South Wales, Australia.
PLoS One. 2014 Oct 10;9(10):e108844. doi: 10.1371/journal.pone.0108844. eCollection 2014.
Postprandial hyperglycemia induces inflammation and endothelial dysfunction resulting in vascular complications in patients with diabetes. Toll-like receptors (TLRs) are central to the regulation of inflammatory responses through activation of nuclear factor-kappa B (NF-ĸB). This study examined the role of TLR2 and 4 in regulating inflammation and endothelial dysfunction when exposed to fluctuating glucose concentrations. HMEC-1 cells (a human microvascular endothelial cell line) were exposed to control (5 mM), 30 mM (high), fluctuating (5/30 mM) and 11.2 mM glucose (approximate glycaemic criteria for the diagnosis of diabetes mellitus) for 72 h. Cells were assessed for TLR2, 4, high mobility group box -1 (HMGB1), NF-ĸB, monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Fluctuating glucose concentrations maximally upregulated TLR4 but not TLR2 expression with increased NF-ĸB activation, IL-8 and ICAM-1 expression. HMGB1 was increased in the supernatants of cells exposed to 30 mM and 11.2 mM glucose compared to control. The addition of recombinant HMGB1 induced NF-ĸB activation and synthesis of proinflammatory cytokines and chemokines, which were prevented by TLR2 or 4 signalling inhibition. An additive effect when both TLR2 and 4 signalling pathways were inhibited was observed. However, only inhibition of TLR4 signalling suppressed the synthesis of MCP-1, IL-8 and ICAM-1. In vivo, streptozotocin-induced diabetic mice exhibited an increase in glomerular ICAM-1 which was not evident in TLR2(-/-) or TLR4(-/-) diabetic mice. Collectively, our results suggest that targeting the signalling pathway of TLR2 and 4 may be of therapeutic benefit in attenuating vascular inflammation in diabetic microangiopathy.
餐后高血糖会引发炎症和内皮功能障碍，从而导致糖尿病患者出现血管并发症。Toll样受体（TLR）通过激活核因子-κB（NF-κB）在炎症反应调节中起核心作用。本研究探讨了TLR2和TLR4在暴露于波动血糖浓度时对炎症调节和内皮功能障碍的作用。将人微血管内皮细胞系HMEC-1细胞分别暴露于对照（5 mM）、30 mM（高）、波动（5/30 mM）和11.2 mM葡萄糖（糖尿病诊断的近似血糖标准）中72小时。评估细胞中的TLR2、TLR4、高迁移率族蛋白B1（HMGB1）、NF-κB、单核细胞趋化蛋白-1（MCP-1）、白细胞介素-8（IL-8）、细胞间黏附分子-1（ICAM-1）和血管细胞黏附分子-1（VCAM-1）。波动的血糖浓度最大程度地上调了TLR4而非TLR2的表达，同时增加了NF-κB激活、IL-8和ICAM-1的表达。与对照相比，暴露于30 mM和11.2 mM葡萄糖的细胞上清液中HMGB1增加。添加重组HMGB1可诱导NF-κB激活以及促炎细胞因子和趋化因子的合成，而TLR2或TLR4信号抑制可阻止这种合成。当TLR2和TLR4信号通路均被抑制时观察到相加效应。然而，只有抑制TLR4信号通路才能抑制MCP-1、IL-8和ICAM-1的合成。在体内，链脲佐菌素诱导的糖尿病小鼠肾小球ICAM-1增加，而在TLR2（-/-）或TLR4（-/-）糖尿病小鼠中不明显。总体而言，我们的结果表明，靶向TLR2和TLR4的信号通路可能对减轻糖尿病微血管病变中的血管炎症具有治疗益处。
