Lee H Thomas, Kim Mihwa, Kim Jeehee, Kim Nala, Emala Charles W
Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032-3784, USA.
Am J Nephrol. 2007;27(4):416-24. doi: 10.1159/000105124. Epub 2007 Jul 3.
BACKGROUND/AIMS: We have previously demonstrated that clinically utilized volatile anesthetics protect against renal ischemia reperfusion injury in rats in vivo and reduce necrosis in vitro via activation of ERK and Akt and by upregulating HSP70. In this study, we further deciphered the upstream cellular signaling mechanism(s) of volatile anesthetic-mediated antinecrotic effects in vitro. We hypothesized that volatile anesthetics perturb the structure of the plasma membrane lipid bilayer, causing externalization of phosphatidylserine (PS) to the outer surface on renal tubule cells leading to the increased generation of transforming growth factor-beta1 (TGF-beta1), a cytokine with antinecrotic properties.
In human proximal tubule (HK-2) cell culture, 16-hour exposure to volatile anesthetics (isoflurane, halothane, sevoflurane) caused membrane externalization of PS detected by positive annexin-V staining and increased the release of TGF-beta1 into the cell culture media. Exogenous TGF-beta1 induced protection and neutralizing TGF-beta1 antibody prevented the cytoprotection by volatile anesthetics against hydrogen peroxide-induced HK-2 cell necrosis.
Volatile anesthetics induce a cytoprotective signaling cascade in proximal tubule cells via membrane externalization of PS initiating TGF-beta1-mediated cytoprotection.
背景/目的：我们之前已经证明，临床使用的挥发性麻醉剂在体内可保护大鼠免受肾缺血再灌注损伤，并通过激活细胞外信号调节激酶（ERK）和蛋白激酶B（Akt）以及上调热休克蛋白70（HSP70）来减少体外坏死。在本研究中，我们进一步解析了挥发性麻醉剂在体外介导抗坏死作用的上游细胞信号传导机制。我们推测挥发性麻醉剂扰乱质膜脂质双层结构，导致肾小管细胞上磷脂酰丝氨酸（PS）外化至外表面，从而导致具有抗坏死特性的细胞因子转化生长因子-β1（TGF-β1）生成增加。
在人近端小管（HK-2）细胞培养中，暴露于挥发性麻醉剂（异氟烷、氟烷、七氟烷）16小时会导致PS膜外化，通过膜联蛋白-V阳性染色检测到，并增加TGF-β1释放到细胞培养基中。外源性TGF-β1诱导保护作用，而中和TGF-β1抗体可阻止挥发性麻醉剂对过氧化氢诱导的HK-2细胞坏死的细胞保护作用。
挥发性麻醉剂通过PS膜外化引发TGF-β1介导的细胞保护作用，在近端小管细胞中诱导细胞保护信号级联反应。
