Primer Khalia R, Tan Joanne T M, Sandeman Lauren, Nankivell Victoria A, Stretton Liam G, Solly Emma L, Psaltis Peter J, Bursill Christina A
Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, South Australia, Australia (K.R.P., J.T.M.T., V.A.N., L.G.S., E.L.S., P.J.P., C.A.B.).
Vascular Research Centre, Lifelong Health Theme, South Australian Health and Medical Research Centre, Adelaide, Australia (K.R.P., J.T.M.T., L.S., V.A.N., L.G.S., E.L.S., P.J.P., C.A.B.).
Arterioscler Thromb Vasc Biol. 2025 May;45(5):683-701. doi: 10.1161/ATVBAHA.124.320110. Epub 2025 Mar 20.
Impaired angiogenic responses to ischemia underlie diabetic vascular complications. Reconstituted high-density lipoproteins (rHDLs) have proangiogenic effects in diabetes. The PDK4 (pyruvate dehydrogenase kinase 4)/PDC (pyruvate dehydrogenase complex) axis is an oxygen-conserving mechanism that preserves endothelial cell function in hypoxia. We aimed to determine the role of the PDK4/PDC axis in angiogenesis, the effect of diabetes on its regulation in response to ischemia, and the proangiogenic properties of rHDL.
Expression of PDK4 and phosphorylated PDC (pPDC) were measured in PBS- or rHDL-treated wounds of nondiabetic and streptozotocin-induced diabetic mice and PBS- or rHDL-treated endothelial cells exposed to glucose and hypoxia. The importance of PDK4 in the action of rHDL was determined by siRNA knockdown in vitro and PDK4 inhibitor in vivo. Chromatin immunoprecipitation assay was performed to identify the mechanism for PDK4 induction by rHDL.
PDK4 and pPDC were elevated early (24 hours) post-induction of wound ischemia in nondiabetic wounds, which did not occur in diabetic mice. Topical rHDL rescued this impairment, enhancing PDK4 (68%; =0.0041) and pPDC (165%; =0.029) in diabetic wounds. Wound neovascularization (62%; <0.05) and closure (154%; <0.001) were increased in diabetic rHDL-treated wounds. In vitro, PDK4 and pPDC levels were increased with hypoxia (65%, =0.043 and 64%, =0.026, respectively). High glucose did not elicit a further stepwise induction in PDK4/pPDC, with aberrant increases in mitochondrial respiration (19%; =0.026), and impaired angiogenic functions. Importantly, rHDL increased PDK4 and pPDC 2-fold, returning mitochondrial respiration and angiogenic functions to normal glucose levels. PDK4 inhibition ameliorated the proangiogenic effects of rHDL. rHDL increased FOXO1 (forkhead box O1) binding to the PDK4 promoter and suppressed FOXO1 phosphorylation, presenting FOXO1 as a mechanism for rHDL-mediated induction of PDK4.
The PDK4/PDC axis response to ischemia is impaired in diabetes and is important for the proangiogenic effects of rHDL.
对缺血的血管生成反应受损是糖尿病血管并发症的基础。重组高密度脂蛋白（rHDL）在糖尿病中具有促血管生成作用。丙酮酸脱氢酶激酶4（PDK4）/丙酮酸脱氢酶复合体（PDC）轴是一种在缺氧状态下维持内皮细胞功能的氧保存机制。我们旨在确定PDK4/PDC轴在血管生成中的作用、糖尿病对其缺血反应调节的影响以及rHDL的促血管生成特性。
在非糖尿病小鼠和链脲佐菌素诱导的糖尿病小鼠经PBS或rHDL处理的伤口中，以及在暴露于葡萄糖和缺氧环境的经PBS或rHDL处理的内皮细胞中，检测PDK4和磷酸化PDC（pPDC）的表达。通过体外小干扰RNA敲低和体内PDK4抑制剂确定PDK4在rHDL作用中的重要性。进行染色质免疫沉淀试验以确定rHDL诱导PDK4的机制。
在非糖尿病伤口诱导伤口缺血后早期（24小时），PDK4和pPDC升高，而糖尿病小鼠未出现这种情况。局部应用rHDL挽救了这种损伤，使糖尿病伤口中的PDK4（68%；P = 0.0041）和pPDC（165%；P = 0.029）增加。糖尿病rHDL处理的伤口中伤口新生血管形成（62%；P < 0.05）和愈合（154%；P < 0.001）增加。在体外，缺氧时PDK4和pPDC水平升高（分别为65%，P = 0.043和64%，P = 0.026）。高糖并未引起PDK4/pPDC的进一步逐步诱导，同时线粒体呼吸异常增加（19%；P = 0.026），血管生成功能受损。重要的是，rHDL使PDK4和pPDC增加2倍，使线粒体呼吸和血管生成功能恢复到正常葡萄糖水平。抑制PDK4可改善rHDL的促血管生成作用。rHDL增加了叉头框O1（FOXO1）与PDK4启动子的结合并抑制了FOXO1磷酸化，提示FOXO1是rHDL介导的PDK4诱导机制。
糖尿病中PDK4/PDC轴对缺血的反应受损，且对rHDL的促血管生成作用很重要。
