Peripheral artery disease (PAD) is a major health problem and is caused by atherosclerosis in arteries outside the heart leading to impaired blood flow. The presence of diabetes significantly increases the likelihood of having worse outcomes in PAD, and the molecular mechanisms involved are poorly understood. Hyperglycemia in diabetes activates the nuclear factor-kappa B (NF-κB) pathway, and chronic inflammation in diabetes is associated with vascular complications. Ischemia also activates NF-κB signaling that is important for perfusion recovery in experimental PAD. We hypothesized that prolonged exposure of endothelial cells to high glucose in diabetes impairs ischemic activation of the NF-κB pathway and contributes to poor perfusion recovery in experimental PAD. We assessed the effect of high glucose and ischemia on canonical and non-canonical NF-κB activation in endothelial cells and found both conditions activate both pathways. However, exposure of endothelial cells to high glucose impairs ischemia-induced activation of the canonical NF-κB pathway but not the non-canonical pathway. We probed an array of antibodies against signaling proteins in the NF-κB pathway to identify proteins whose phosphorylation status are altered in endothelial cells exposed to high glucose. Protein kinase C beta (PKCβ) was among the proteins identified, and its role in impaired ischemia-induced activation of NF-κB during hyperglycemia has not been previously described. Inhibition of PKCβ improves ischemia-induced NF-κB activation in vitroand in vivo. It also improves perfusion recovery in diabetic mice following experimental PAD. Thus, in diabetes, PKCβ phosphorylation contributes to impaired ischemic activation of NF-κB and likely a mechanism contributing to poor PAD outcomes.

Impact statement

Diabetes worsens the outcomes of peripheral arterial disease (PAD) likely in part through inducing chronic inflammation. However, in PAD, recovery requires the nuclear factor-kappa B (NF-κB) activation, a known contributor to inflammation. Our study shows that individually, both ischemia and high glucose activate the canonical and non-canonical arms of the NF-κB pathways. We show for the first time that prolonged high glucose specifically impairs ischemia-induced activation of the canonical NF-κB pathway through activation of protein kinase C beta (PKCβ). Accordingly, inhibition of PKCβ restores the ischemia-induced NF-κB activity both in vitroin endothelial cells and in vivoin hind limbs of type 1 diabetic mice and improves perfusion recovery after experimental PAD. Thus, this study provides a mechanistic insight into how diabetes contributes to poor outcomes in PAD and a potential translational approach to improve PAD outcomes.

中文翻译：

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专题文章：抑制蛋白激酶 C β 磷酸化可激活核因子 kappa B 并改善 1 型糖尿病的缺血后恢复。

外周动脉疾病（PAD）是一个主要的健康问题，是由心脏外动脉粥样硬化导致血流受损引起的。糖尿病的存在显着增加了 PAD 出现更差结果的可能性，而其中涉及的分子机制尚不清楚。糖尿病中的高血糖会激活核因子-κB (NF-κB) 通路，而糖尿病中的慢性炎症与血管并发症相关。缺血还会激活 NF-κB 信号传导，这对于实验性 PAD 的灌注恢复非常重要。我们假设，糖尿病患者内皮细胞长时间暴露于高葡萄糖会损害 NF-κB 通路的缺血性激活，并导致实验性 PAD 的灌注恢复不良。我们评估了高血糖和缺血对内皮细胞中典型和非典型 NF-κB 激活的影响，发现这两种情况都会激活这两条通路。然而，内皮细胞暴露于高葡萄糖会损害缺血诱导的经典 NF-κB 通路的激活，但不会损害非经典通路。我们探测了一系列针对 NF-κB 通路中信号蛋白的抗体，以鉴定在暴露于高葡萄糖的内皮细胞中磷酸化状态发生改变的蛋白质。蛋白激酶 C beta (PKCβ) 是已识别的蛋白质之一，其在高血糖期间缺血诱导的 NF-κB 激活受损中的作用尚未被描述。 PKCβ 的抑制可改善缺血诱导的 NF-κB体外和体内激活。它还可以改善实验性 PAD 后糖尿病小鼠的灌注恢复。 因此，在糖尿病中，PKCβ 磷酸化会导致 NF-κB 缺血性激活受损，并且可能是导致 PAD 预后不良的机制。

 影响报告

糖尿病可能部分通过诱发慢性炎症而恶化外周动脉疾病（PAD）的结果。然而，在 PAD 中，恢复需要核因子 kappa B (NF-κB) 激活，这是已知的炎症促成因素。我们的研究表明，缺血和高血糖单独激活 NF-κB 通路的经典和非经典分支。我们首次证明，长时间的高血糖会通过激活蛋白激酶 C β (PKCβ) 来特异性损害缺血诱导的经典 NF-κB 通路的激活。因此，抑制 PKCβ 可恢复内皮细胞体外和 1 型糖尿病小鼠后肢体内缺血诱导的 NF-κB 活性，并改善实验性 PAD 后的灌注恢复。因此，这项研究提供了关于糖尿病如何导致 PAD 不良结局的机制见解，以及改善 PAD 结局的潜在转化方法。