Department of General Surgery, Guangdong General Hospital, Guangzhou, Guangdong Province, China ; Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province, China.
PLoS One. 2013 Sep 9;8(9):e72593. doi: 10.1371/journal.pone.0072593. eCollection 2013.
Accumulating evidence supports the early involvement of monocyte/macrophage recruitment to activated endothelial cells by leukocyte adhesion molecules during atherogenesis. CD40 and its ligand CD40L are highly expressed in vascular endothelial cells, but its impact on monocyte adhesion and the related molecular mechanisms are not fully understood. The present study was designed to evaluate the direct effect of CD40L on monocytic cell adhesion and gain mechanistic insight into the signaling coupling CD40L function to the proinflammatory response. Exposure of cultured human aortic endothelial cells (HAECs) to clinically relevant concentrations of CD40L (20 to 80 ng/mL) dose-dependently increased human monocytic THP-1 cells to adhere to them under static condition. CD40L treatment induced the expression of vascular cell adhesion molecule-1 (VCAM-1) mRNA and protein expression in HAECs. Furthermore, exposure of HAECs to CD40L robustly increased the activation of protein kinase C beta (PKCβ) in ECs. A selective inhibitor of PKCβ prevented the rise in VCAM-1 and THP-1 cell adhesion to ECs. Moreover, stimulation of ECs to CD40L induced nuclear factor-κB (NF-κB) activation. PKCβ inhibition abolished CD40L-induced NF-κB activation, and NF-κB inhibition reduced expression of VCAM-1, each resulting in reduced THP-1 cell adhesion. Our findings provide the evidence that CD40L increases VCAM-1 expression in ECs by activating PKCβ and NF-κB, suggesting a novel mechanism for EC activation. Finally, administration of CD40L resulted in PKCβ activation, increased VCAM-1 expression and activated monocytes adhesiveness to HAECs, processes attenuated by PKCβ inhibitor. Therefore, CD40L may contribute directly to atherogenesis by activating ECs and recruiting monocytes to them.
越来越多的证据表明，在动脉粥样硬化形成过程中，白细胞黏附分子使单核细胞/巨噬细胞募集到活化的内皮细胞。CD40 及其配体 CD40L 在血管内皮细胞中高度表达，但它对单核细胞黏附的影响及其相关的分子机制尚不完全清楚。本研究旨在评估 CD40L 对单核细胞黏附的直接作用，并深入了解 CD40L 功能与促炎反应相关的信号偶联。在静态条件下，将临床相关浓度（20 至 80ng/ml）的 CD40L 暴露于培养的人主动脉内皮细胞（HAEC）中，可剂量依赖性地增加人单核细胞 THP-1 细胞黏附到它们。CD40L 处理诱导 HAEC 中血管细胞黏附分子-1（VCAM-1）mRNA 和蛋白表达。此外，CD40L 暴露可使 EC 中蛋白激酶 Cβ（PKCβ）的激活显著增加。PKCβ 的选择性抑制剂可防止 VCAM-1 和 THP-1 细胞黏附到 ECs 的增加。此外，刺激 EC 对 CD40L 诱导核因子-κB（NF-κB）激活。PKCβ 抑制消除了 CD40L 诱导的 NF-κB 激活，NF-κB 抑制降低了 VCAM-1 的表达，从而降低了 THP-1 细胞的黏附。我们的研究结果提供了证据，表明 CD40L 通过激活 PKCβ 和 NF-κB 增加 EC 中 VCAM-1 的表达，这表明了 EC 激活的新机制。最后，CD40L 的给药导致 PKCβ 的激活，增加 VCAM-1 的表达，并激活单核细胞黏附到 HAEC，这些过程被 PKCβ 抑制剂减弱。因此，CD40L 通过激活 EC 并将单核细胞募集到它们来直接促进动脉粥样硬化的形成。
