Elksnis Andris, Cen Jing, Wikström Per, Carlsson Per-Ola, Welsh Nils
Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, SE-751 23 Uppsala, Sweden.
Glucox Biotech AB, Frälsegårdsvägen 8, SE-179 97 Färentuna, Sweden.
Biomedicines. 2021 Dec 8;9(12):1865. doi: 10.3390/biomedicines9121865.
Previous studies have reported beneficial effects of NADPH oxidase 4 (NOX4) inhibition on beta-cell survival in vitro and in vivo. The mechanisms by which NOX4 inhibition protects insulin producing cells are, however, not known. The aim of the present study was to investigate the effects of a pharmacological NOX4 inhibitor (GLX7013114) on human islet and EndoC-βH1 cell mitochondrial function, and to correlate such effects with survival in islets of different size, activity, and glucose-stimulated insulin release responsiveness. We found that maximal oxygen consumption rates, but not the rates of acidification and proton leak, were increased in islets after acute NOX4 inhibition. In EndoC-βH1 cells, NOX4 inhibition increased the mitochondrial membrane potential, as estimated by JC-1 fluorescence; mitochondrial reactive oxygen species (ROS) production, as estimated by MitoSOX fluorescence; and the ATP/ADP ratio, as assessed by a bioluminescent assay. Moreover, the insulin release from EndoC-βH1 cells at a high glucose concentration increased with NOX4 inhibition. These findings were paralleled by NOX4 inhibition-induced protection against human islet cell death when challenged with high glucose and sodium palmitate. The NOX4 inhibitor protected equally well islets of different size, activity, and glucose responsiveness. We conclude that pharmacological alleviation of NOX4-induced inhibition of beta-cell mitochondria leads to increased, and not decreased, mitochondrial ROS, and this was associated with protection against cell death occurring in different types of heterogeneous islets. Thus, NOX4 inhibition or modulation may be a therapeutic strategy in type 2 diabetes that targets all types of islets.
先前的研究报道了抑制NADPH氧化酶4（NOX4）在体外和体内对β细胞存活具有有益作用。然而，NOX4抑制保护胰岛素生成细胞的机制尚不清楚。本研究的目的是研究一种药理学NOX4抑制剂（GLX7013114）对人胰岛和EndoC-βH1细胞线粒体功能的影响，并将这些影响与不同大小、活性和葡萄糖刺激的胰岛素释放反应性的胰岛中的细胞存活情况相关联。我们发现，急性抑制NOX4后，胰岛中的最大氧消耗率增加，但酸化率和质子泄漏率未增加。在EndoC-βH1细胞中，通过JC-1荧光估计，NOX4抑制增加了线粒体膜电位；通过MitoSOX荧光估计，增加了线粒体活性氧（ROS）的产生；通过生物发光测定评估，增加了ATP/ADP比值。此外，在高葡萄糖浓度下，EndoC-βH1细胞的胰岛素释放随着NOX4抑制而增加。当用高葡萄糖和棕榈酸钠刺激时，这些发现与NOX4抑制诱导的对人胰岛细胞死亡的保护作用相平行。NOX4抑制剂对不同大小、活性和葡萄糖反应性的胰岛具有同样好的保护作用。我们得出结论，药理学减轻NOX4诱导的对β细胞线粒体的抑制会导致线粒体ROS增加而非减少，这与保护不同类型的异质性胰岛中发生的细胞死亡有关。因此，抑制或调节NOX4可能是2型糖尿病的一种针对所有类型胰岛的治疗策略。
