An approach to understand the interaction of lipoproteins and vascular endothelial cells

(1)脂蛋白和溶脂对内皮依赖性松弛的影响我们已经证明，氧化低密度脂蛋白（ox-LDL）中的溶血磷脂酰胆碱（LPC）抑制内皮细胞中EDRF/NO的合成。LPC和ox-LDL抑制细胞内信号转导，这种信号转导将受体刺激与内皮细胞第二信使的生物合成联系起来，导致内皮细胞内钙信号的产生出现内皮缺陷，而细胞内钙信号是激活NO合酶所必需的。(2)内皮NO合成酶（NOS）的调控我们从培养的牛主动脉内皮细胞（BAECs）中纯化了内皮NO合成酶。内皮细胞NOS主要在NADPH、FAD和BH_4辅助因子存在的情况下受到Ca^<2+>/calmodulin的调控。PC、LPC和磷脂酰乙醇酰胺可使NOS活性提高约3倍。检测baec中NOS mRNA的表达。LPC或ox-LDL增强NOS mRNA表达。干扰素α / β增加NOS mRNA表达，tnf α抑制其表达。(3)血管平滑肌细胞诱导型NOS (iNOS) mRNA表达的调控。干扰素γ、TNF α和白细胞介素-1 β均在亚硝酸盐产生的同时显著升高iNOS mRNA和蛋白水平。tgf - β显著抑制了这些细胞因子引起的蛋白质水平升高。

(1) Effect of lipoproteins and lysolipids on endothelium-dependent relaxationWe have demonstrated that lysophosphatidylcholine (LPC) in oxidized low density lipoprotein (ox-LDL) inhibits the synthesis of EDRF/NO in endothelial cells. LPC and ox-LDL inhibit the intracellular signal transduction which links the receptor stimulation to biosynthesis of the second massenger in endothelial cells, leading to an endothelial defect in the generation at appropriate intracellular calcium signals nesessary for activation of NO synthase. HDL reverses the ox-LDL-induced impairment of endothelium-dependent relaxation by removing LPC from ox-LDL(2) Regulation of endothelial NO synthase (NOS)We have purified endothelial NOS from cultured bovine aortic endothelial cells (BAECs). Endothelial NOS was mainly regulated Ca^<2+>/calmodulin in the presence of NADPH,FAD and BH_4 as cofactors. NOS activity was enhanced approximately up to three fold by PC, LPC and phosphatidylethanolamice. NOS mRNA expression was investigated in BAECs. LPC or ox-LDL enhanced NOS mRNA expression.Interferon alpha/beta increased NOS mRNA expression, but TNF-alpha inhibited it.(3) Regulation of inducible NOS (iNOS) mRNA expression in vascular smooth muscle cells. interferon gamma, TNF alpha and interleukin-1beta each markedly increased mRNA and protein levels of iNOS in parallel with the production of nitrite. TGF-beta significantly inhibited the increase in protein levels caused by these cytokines.