The Lloyd Rigler Sleep Apnea Research Laboratory, Unit of Anatomy and Cell Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Eur J Cell Biol. 2012 Aug;91(8):640-53. doi: 10.1016/j.ejcb.2012.02.003. Epub 2012 Apr 2.
Fibronectin (FN) is an extracellular matrix protein promoting cell proliferation, adhesion, and survival and is localized in the intimal layer of normal and atherosclerotic blood vessels. Dendritic cells (DCs) are potent antigen-presenting cells located in healthy and diseased intima, and thus may predispose arteries to atherosclerosis. Besides their pro-atherogenic activities DCs can promote neovascularization, by releasing pro-angiogenic mediators and/or by trans-differentiating into endothelial-like cells. Here, we investigated changes in morphology, function and angiogenic properties of monocyte-derived immature DCs (Mo-iDCs) after a short-term FN treatment and some of the signaling pathways involved in these processes. The cells were analyzed by time-lapse, confocal microscopy and flow cytometry. Within 90 min of re-plating, FN induced a swift morphologic transformation of most round iDCs into spindle-shaped iDCs (sp-iDCs). This was characterized by redistribution of mitochondria into dendritic spindles, decreased CD1c, and increased thrombomodulin (CD141) expression. Functionally, sp-iDCs acquired Ulex-europaeus-agglutinin-1 lectin binding, phagocytosis was decreased and intracellular (nuclear and cytosolic) vascular endothelial growth factor (VEGF) was increased. FN also induced ERK1/2 phosphorylation in round-iDCs, and p38MAPK phosphorylation in sp-iDCs. Inhibiting p38MAPK, but not ERK1/2, restrained the FN-induced transformation into sp-iDCs. Furthermore, FN-treatment of Mo-iDCs induced a paracrine angiogenic effect on endothelial tube formation, which was abolished by inhibiting ERK1/2 or VEGF. Inhibiting p38MAPK had no effect on endothelial tube formation. By contrast, in laminin-treated Mo-iDCs, which had round-shaped morphology, CD1c and CD141 expression was similar to control untreated cells, but intracellular VEGF levels were higher, and endothelial tube formation was an individual trait. We conclude that a short-term FN treatment induced angiogenic intracrine and paracrine properties in Mo-iDCs. This may act as an immediate protective mechanism to maintain vascular homeostasis. Moreover, inducing sp-iDCs by short term FN-treatment or ERK1/2 modulation might be considered as new approaches for regulating angiogenesis through the production/inhibition of pro-angiogenic mediators. Collectively, these findings may support a role for FN and Mo-iDCs in vascular function and angiogenesis.
纤连蛋白（FN）是一种细胞外基质蛋白，可促进细胞增殖、黏附和存活，并定位于正常和动脉粥样硬化血管的内膜层。树突状细胞（DCs）是位于健康和患病内膜中的有效抗原呈递细胞，因此可能使动脉易患动脉粥样硬化。除了其促动脉粥样硬化活性外，DCs 还可以通过释放促血管生成介质和/或转分化为内皮样细胞来促进新血管形成。在这里，我们研究了 FN 短期处理后单核细胞来源的未成熟 DC（Mo-iDCs）的形态、功能和血管生成特性的变化，以及涉及这些过程的一些信号通路。通过延时、共聚焦显微镜和流式细胞术分析细胞。在重新接种后 90 分钟内，FN 快速诱导大多数圆形 iDC 转化为梭形 iDC（sp-iDC）。这表现为线粒体在树突状纺锤体中的重新分布、CD1c 的减少和血栓调节蛋白（CD141）表达的增加。功能上，sp-iDC 获得了 Ulex-europaeus-agglutinin-1 凝集素结合，吞噬作用降低，细胞内（核和胞质）血管内皮生长因子（VEGF）增加。FN 还诱导圆形 iDC 中 ERK1/2 的磷酸化，以及 sp-iDC 中 p38MAPK 的磷酸化。抑制 p38MAPK，但不抑制 ERK1/2，可抑制 FN 诱导的 sp-iDC 转化。此外，FN 处理 Mo-iDCs 可诱导内皮管形成的旁分泌血管生成效应，该效应可通过抑制 ERK1/2 或 VEGF 来消除。抑制 p38MAPK 对内皮管形成没有影响。相比之下，在层粘连蛋白处理的 Mo-iDCs 中，形态呈圆形，CD1c 和 CD141 的表达与未经处理的对照细胞相似，但细胞内 VEGF 水平较高，内皮管形成是个体特征。我们得出结论，短期 FN 处理诱导 Mo-iDC 中的血管生成内源性和旁分泌特性。这可能是维持血管内稳态的即时保护机制。此外，通过短期 FN 处理或 ERK1/2 调节诱导 sp-iDCs 可能被认为是通过产生/抑制促血管生成介质来调节血管生成的新方法。总的来说，这些发现可能支持 FN 和 Mo-iDCs 在血管功能和血管生成中的作用。
