Heermeier Kathrin, Leicht Wolfgang, Palmetshofer Alois, Ullrich Markus, Wanner Christoph, Galle Jan
University Hospital, Department of Medicine, Division of Nephrology, University of Würzburg, Würzburg, Germany.
Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Würzburg, Germany.
J Am Soc Nephrol. 2001 Mar;12(3):456-463. doi: 10.1681/ASN.V123456.
Atherosclerosis is a chronic inflammatory disease associated with enhanced apoptotic cell death in vascular cells, partly induced by oxidized low-density lipoprotein (OxLDL). However, proinflammatory stimuli such as lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) activate endothelial cells (EC) and inhibit apoptosis through induction of nuclear factor kappaB (NF-kappaB)-dependent genes. This study therefore investigated whether OxLDL or its component, lysophosphatidylcholine (LPC), interacts with the effect of LPS or TNF-alpha on cell survival. Human EC were incubated with LPS, TNF-alpha, OxLDL, or LPC alone or in combinations. OxLDL (100 to 200 microg/ml) and LPC (100 to 300 microM) induced apoptosis dose-dependently. LPS and TNF-alpha had no effect on cell survival in the presence or absence of OxLDL or LPC. LPS and TNF-alpha both induced the antiapoptotic gene A20, whereas OxLDL and LPC suppressed its induction. Expression of A20 is regulated by NF-kappaB. OxLDL and LPC dose-dependently suppressed NF-kappaB activity. For functional analysis, bovine EC were transfected with A20 encoding expression constructs in sense and antisense orientation. Bovine EC that overexpressed A20 were protected against OxLDL-induced apoptosis, whereas expression of antisense A20 rendered cells more sensitive to OxLDL. These results suggest that OxLDL not only induces cell death, as has been shown before, but also compromises antiapoptotic protection of activated EC. OxLDL sensitizes EC to apoptotic triggers by interfering with the induction of A20 during the inflammatory response seen in atherosclerotic lesions. This inhibition is based on repression of NF-kappaB activation. The effect may be caused by the OxLDL component LPC.
动脉粥样硬化是一种慢性炎症性疾病，与血管细胞中凋亡性细胞死亡增加有关，部分是由氧化型低密度脂蛋白（OxLDL）诱导的。然而，促炎刺激物如脂多糖（LPS）或肿瘤坏死因子-α（TNF-α）可激活内皮细胞（EC）并通过诱导核因子κB（NF-κB）依赖性基因来抑制细胞凋亡。因此，本研究调查了OxLDL或其成分溶血磷脂酰胆碱（LPC）是否与LPS或TNF-α对细胞存活的影响相互作用。将人EC单独或联合用LPS、TNF-α、OxLDL或LPC孵育。OxLDL（100至200μg/ml）和LPC（100至300μM）剂量依赖性地诱导细胞凋亡。在存在或不存在OxLDL或LPC的情况下，LPS和TNF-α对细胞存活没有影响。LPS和TNF-α均诱导抗凋亡基因A20，而OxLDL和LPC抑制其诱导。A20的表达受NF-κB调节。OxLDL和LPC剂量依赖性地抑制NF-κB活性。为了进行功能分析，将编码A20的表达构建体以正义和反义方向转染牛EC。过表达A20的牛EC对OxLDL诱导的细胞凋亡具有抗性，而反义A20的表达使细胞对OxLDL更敏感。这些结果表明，OxLDL不仅如先前所示诱导细胞死亡，而且还损害活化EC的抗凋亡保护。OxLDL通过干扰动脉粥样硬化病变中炎症反应期间A20的诱导，使EC对凋亡触发因素敏感。这种抑制是基于对NF-κB激活的抑制。这种作用可能是由OxLDL成分LPC引起的。
