Clinic of Anaesthesiology, Intensive Care Medicine, and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
Resuscitation. 2012 Nov;83(11):1404-10. doi: 10.1016/j.resuscitation.2012.04.001. Epub 2012 Apr 12.
Absence or inhibition of Toll-like receptor 2 (TLR2) signalling during murine myocardial ischaemia/reperfusion (MI/R) decreases myocardial necrosis and inflammation, thereby ameliorating cardiac dysfunction and improving survival. In the present study, we provide evidence for the involvement of the phosphoinositide-3-kinase/Akt pathway in TLR2-dependent reperfusion injury.
Adult male wild-type (WT) and TLR2(-/-) mice were subjected to myocardial ischaemia (30min) and reperfusion (4h). Animals were treated with phosphoinositide-3-kinase inhibitor wortmannin, Akt inhibitor V (triciribine), or vehicle 1h prior to MI/R. Protein expression levels of Akt1 and phosphoinositide-3-kinase and their respective phosphorylated forms were determined by Western blot analysis. Myocardial necrosis was quantified after staining with the tetrazolium method and by troponin T plasma levels.
TLR2(-/-) mice displayed significantly increased Akt and phospho-Akt levels compared to WT mice, whilst no significant difference in phosphoinositide-3-kinase expression and phosphorylation could be observed. TLR2(-/-) mice also showed a blunted myocardial necrosis, the extent of which inversely correlated with Akt expression and degree of phosphorylation. Pharmacological inhibition of both, phosphoinositide-3-kinase or Akt, reversed the cardioprotection observed in TLR2(-/-) mice, whilst no effect could be observed in WT mice.
Akt is an important mediator of cardioprotection in TLR2(-/-) animals during MI/R. The effect is, however, likely mediated by its genomic overexpression in the heart of TLR2(-/-) animals whilst Akt activation by phosphoinositide-3-kinase is unaltered.
在小鼠心肌缺血/再灌注（MI/R）期间，Toll 样受体 2（TLR2）信号的缺失或抑制可减少心肌坏死和炎症，从而改善心功能障碍和提高存活率。在本研究中，我们提供了证据表明，磷脂酰肌醇 3-激酶/蛋白激酶 B（Akt）途径参与 TLR2 依赖性再灌注损伤。
成年雄性野生型（WT）和 TLR2（-/-）小鼠进行心肌缺血（30min）和再灌注（4h）。动物在 MI/R 前 1h 用磷脂酰肌醇 3-激酶抑制剂wortmannin、Akt 抑制剂 V（triciribine）或载体处理。通过 Western blot 分析测定 Akt1 和磷脂酰肌醇 3-激酶及其相应磷酸化形式的蛋白表达水平。通过四唑盐法染色和肌钙蛋白 T 血浆水平来定量心肌坏死。
与 WT 小鼠相比，TLR2（-/-）小鼠显示出明显增加的 Akt 和磷酸化 Akt 水平，而磷脂酰肌醇 3-激酶的表达和磷酸化没有明显差异。TLR2（-/-）小鼠也表现出心肌坏死减弱，其程度与 Akt 表达和磷酸化程度呈负相关。磷脂酰肌醇 3-激酶或 Akt 的药理学抑制均逆转了 TLR2（-/-）小鼠观察到的心脏保护作用，而在 WT 小鼠中则没有观察到这种作用。
在 MI/R 期间，Akt 是 TLR2（-/-）动物心脏保护的重要介质。然而，这种作用可能是由 TLR2（-/-）动物心脏中 Akt 的基因组过度表达介导的，而磷脂酰肌醇 3-激酶的 Akt 激活则未改变。
