Center for Metabolic Research, Veterans Affairs San Diego Healthcare System, San Diego, CA, 92161, USA.
Department of Medicine, University of California, San Diego, La Jolla, CA, 92093-0021, USA.
Mol Biol Rep. 2021 Jan;48(1):601-610. doi: 10.1007/s11033-020-06104-z. Epub 2021 Jan 7.
Angiogenesis is a multistep process requiring endothelial cell activation, migration, proliferation and tube formation. We recently reported that elevated secretion of interlukin 8 (IL8) by myotubes (MT) from subjects with Type-2 Diabetes (T2D) reduced angiogenesis by human umbilical vein endothelial cells (HUVEC) and human skeletal muscle explants. This lower vascularization was mediated through impaired activation of the phosphatidylinositol 3-kinase (PI3K)-pathway. We sought to investigate additional signaling elements that might mediate reduced angiogenesis. HUVEC were exposed to levels of IL8 equal to those secreted by MT from non-diabetic (ND) and T2D subjects and the involvement of components in the angiogenic response pathway examined. Cellular content of reactive oxygen species and Nitrate secretion were similar after treatment with [ND-IL8] and [T2D-IL8]. CXCR1 protein was down-regulated after treatment with [T2D-IL8] (p < 0.01 vs [ND-IL8] treatment); CXCR2 expression was unaltered. Addition of neutralizing antibodies against CXCR1 and CXCR2 to HUVEC treated with IL8 confirmed that CXCR1 alone mediated the angiogenic response to IL8. A key modulator of angiogenesis is matrix metalloproteinase-2 (MMP2). MMP2 secretion was higher after treatment with [ND-IL8] vs [T2D-IL8] (p < 0.01). MMP2 inhibition reduced tube formation to greater extent with [ND-IL8] than with [T2D-IL8] (p < 0.005). The PI3K-pathway inhibitor LY294002 reduced IL8-induced MMP2 release. IL8 regulation of MMP2 release was CXCR1 dependent, as anti-CXCR1 significantly reduced MMP2 release (p < 0.05). These results suggest that high levels of IL8 secreted by T2D MT trigger reduced capillarization via lower activation of a CXCR1-PI3K pathway, followed by impaired release and activity of MMP2.
血管生成是一个多步骤的过程，需要内皮细胞的激活、迁移、增殖和管腔形成。我们最近报道，2 型糖尿病（T2D）患者的肌管（MT）升高的白细胞介素 8（IL8）分泌会减少人脐静脉内皮细胞（HUVEC）和人骨骼肌外植体的血管生成。这种较低的血管生成是通过磷酸肌醇 3-激酶（PI3K）途径的激活受损介导的。我们试图研究可能介导血管生成减少的其他信号转导元件。将 HUVEC 暴露于与来自非糖尿病（ND）和 T2D 患者的 MT 分泌相等的 IL8 水平，并检查血管生成反应途径中的成分。用 [ND-IL8] 和 [T2D-IL8] 处理后，细胞内活性氧和硝酸盐分泌的含量相似。用 [T2D-IL8] 处理后，CXCR1 蛋白下调（p < 0.01 与 [ND-IL8] 处理相比）；CXCR2 表达不变。将中和 CXCR1 和 CXCR2 的抗体添加到用 IL8 处理的 HUVEC 中，证实 CXCR1 单独介导了对 IL8 的血管生成反应。血管生成的一个关键调节剂是基质金属蛋白酶-2（MMP2）。用 [ND-IL8] 处理后，MMP2 分泌高于用 [T2D-IL8] 处理（p < 0.01）。与用 [T2D-IL8] 相比，用 MMP2 抑制剂抑制管腔形成的程度更大（p < 0.005）。PI3K 途径抑制剂 LY294002 减少了 IL8 诱导的 MMP2 释放。IL8 对 MMP2 释放的调节依赖于 CXCR1，因为抗 CXCR1 显著减少了 MMP2 的释放（p < 0.05）。这些结果表明，T2D MT 分泌的高水平 IL8 通过降低 CXCR1-PI3K 途径的激活，随后降低 MMP2 的释放和活性，触发血管生成减少。
