Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Krakow, Poland.
Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Krakow, Poland; Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy.
Biochem Pharmacol. 2020 Aug;178:114019. doi: 10.1016/j.bcp.2020.114019. Epub 2020 May 8.
Nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are effective substrates for NAD synthesis, which may act as vasoprotective agents. Here, we characterize the effects of NMN and NR on endothelial inflammation and dysfunction and test the involvement of CD73 in these effects.
The effect of NMN and NR on IL1β- or TNFα-induced endothelial inflammation (ICAM1 and vWF expression), intracellular NAD concentration and NAD-related enzyme expression (NAMPT, CD38, CD73), were studied in HAECs. The effect of NMN and NR on angiotensin II-induced impairment of endothelium-dependent vasodilation was analyzed in murine aortic rings. The involvement of CD73 in NMN and NR effects was tested using CD73 inhibitor-AOPCP, or CD73 mice.
24 h-incubation with NMN and NR induced anti-inflammatory effects in HAEC stimulated by IL1β or TNFα, as evidenced by a reduction in ICAM1 and vWF expression. Effects of exogenous NMN but not NR was abrogated in the presence of AOPCP, that efficiently inhibited extracellular endothelial conversion of NMN to NR, without a significant effect on the metabolism of NMN to NA. Surprisingly, intracellular NAD concentration increased in HAEC stimulated by IL1β or TNFα and this effect was associated with upregulation of NAMPT and CD73, whereas changes in CD38 expression were less pronounced. NMN and NR further increased NAD in IL1β-stimulated HAECs and AOPCP diminished NMN-induced increase in NAD, without an effect on NR-induced response. In ex vivo aortic rings stimulated with angiotensin II for 24 h, NO-dependent vasorelaxation induced by acetylcholine was impaired. NMN and NR, both prevented Ang II-induced endothelial dysfunction in the aorta. In aortic rings taken from CD73 mice NMN effect was lost, whereas NR effect was preserved.
NMN and NR modulate intracellular NAD content in endothelium, inhibit endothelial inflammation and improve NO-dependent function by CD73-dependent and independent pathways, respectively. Extracellular conversion of NMN to NR by CD73 localized in the luminal surface of endothelial cells represent important vasoprotective mechanisms to maintain intracellular NAD.
烟酰胺单核苷酸（NMN）和烟酰胺核苷（NR）是 NAD 合成的有效底物，可能作为血管保护剂发挥作用。在这里，我们研究了 NMN 和 NR 对内皮炎症和功能障碍的影响，并测试了 CD73 在这些影响中的作用。
在 HAECs 中研究了 NMN 和 NR 对 IL1β 或 TNFα 诱导的内皮炎症（ICAM1 和 vWF 表达）、细胞内 NAD 浓度和 NAD 相关酶表达（NAMPT、CD38、CD73）的影响。在小鼠主动脉环中分析了 NMN 和 NR 对血管紧张素 II 诱导的内皮依赖性血管舒张功能障碍的影响。使用 CD73 抑制剂 AOPCP 或 CD73 小鼠测试了 NMN 和 NR 作用中 CD73 的参与。
24 小时孵育 NMN 和 NR 可减轻 IL1β 或 TNFα 刺激的 HAEC 中的炎症反应，表现在 ICAM1 和 vWF 表达减少。在 AOPCP 存在的情况下，外源性 NMN 的作用被阻断，但 NR 的作用不受影响，AOPCP 可有效抑制细胞外 NMN 向 NR 的转化，而对 NMN 向 NA 的代谢没有显著影响。令人惊讶的是，IL1β 或 TNFα 刺激的 HAEC 中细胞内 NAD 浓度增加，这与 NAMPT 和 CD73 的上调有关，而 CD38 表达的变化则不那么明显。NMN 和 NR 进一步增加了 IL1β 刺激的 HAEC 中的 NAD，AOPCP 降低了 NMN 诱导的 NAD 增加，而对 NR 诱导的反应没有影响。在离体主动脉环中，用血管紧张素 II 刺激 24 小时后，乙酰胆碱诱导的一氧化氮依赖性血管舒张功能受损。NMN 和 NR 均可预防血管紧张素 II 引起的主动脉内皮功能障碍。在来自 CD73 小鼠的主动脉环中，NMN 的作用消失，而 NR 的作用仍然存在。
NMN 和 NR 通过 CD73 依赖和独立的途径调节内皮细胞内 NAD 含量，抑制内皮炎症并改善一氧化氮依赖性功能。CD73 定位于内皮细胞的腔表面，将 NMN 转化为 NR，代表维持细胞内 NAD 的重要血管保护机制。
