Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
Int J Mol Sci. 2023 Sep 26;24(19):14585. doi: 10.3390/ijms241914585.
Neutrophils are innate immune cells that play a key role in pathogen clearance. They contribute to inflammatory diseases, including diabetes, by releasing pro-inflammatory cytokines, reactive oxygen species, and extracellular traps (NETs). NETs contain a DNA backbone and catalytically active myeloperoxidase (MPO), which produces hypochlorous acid (HOCl). Chlorination of the DNA nucleoside 8-chloro-deoxyguanosine has been reported as an early marker of inflammation in diabetes. In this study, we examined the reactivity of different chlorinated nucleosides, including 5-chloro-(deoxy)cytidine (5ClC, 5CldC), 8-chloro-(deoxy)adenosine (8ClA, 8CldA) and 8-chloro-(deoxy)guanosine (8ClG, 8CldG), with the INS-1E β-cell line. Exposure of INS-1E cells to 5CldC, 8CldA, 8ClA, and 8CldG decreased metabolic activity and intracellular ATP, and, together with 8ClG, induced apoptotic cell death. Exposure to 8ClA, but not the other nucleosides, resulted in sustained endoplasmic reticulum stress, activation of the unfolded protein response, and increased expression of thioredoxin-interacting protein (TXNIP) and heme oxygenase 1 (HO-1). Exposure of INS-1E cells to 5CldC also increased TXNIP and NAD(P)H dehydrogenase quinone 1 (NQO1) expression. In addition, a significant increase in the mRNA expression of NQO1 and GPx4 was seen in INS-1E cells exposed to 8ClG and 8CldA, respectively. However, a significant decrease in intracellular thiols was only observed in INS-1E cells exposed to 8ClG and 8CldG. Finally, a significant decrease in the insulin stimulation index was observed in experiments with all the chlorinated nucleosides, except for 8ClA and 8ClG. Together, these results suggest that increased formation of chlorinated nucleosides during inflammation in diabetes could influence β-cell function and may contribute to disease progression.
中性粒细胞是先天免疫细胞，在清除病原体方面发挥着关键作用。它们通过释放促炎细胞因子、活性氧物质和细胞外陷阱 (NETs) 来导致炎症性疾病，包括糖尿病。NETs 含有 DNA 骨架和催化活性的髓过氧化物酶 (MPO)，它产生次氯酸 (HOCl)。据报道，在糖尿病中，DNA 核苷 8-氯-脱氧鸟苷的氯化是炎症的早期标志物。在这项研究中，我们检查了不同氯化核苷的反应性，包括 5-氯-(脱氧)胞苷 (5ClC, 5CldC)、8-氯-(脱氧)腺苷 (8ClA, 8CldA) 和 8-氯-(脱氧)鸟苷 (8ClG, 8CldG)，与 INS-1E β 细胞系的反应性。暴露于 INS-1E 细胞的 5CldC、8CldA、8ClA 和 8CldG 降低了代谢活性和细胞内 ATP，并且与 8ClG 一起诱导了细胞凋亡。暴露于 8ClA，但不是其他核苷，导致持续的内质网应激、未折叠蛋白反应的激活以及硫氧还蛋白相互作用蛋白 (TXNIP) 和血红素加氧酶 1 (HO-1) 的表达增加。暴露于 INS-1E 细胞的 5CldC 也增加了 TXNIP 和 NAD(P)H 脱氢酶醌 1 (NQO1) 的表达。此外，在暴露于 8ClG 和 8CldA 的 INS-1E 细胞中，NQO1 和 GPx4 的 mRNA 表达显著增加。然而，仅在暴露于 8ClG 和 8CldG 的 INS-1E 细胞中观察到细胞内硫醇的显著减少。最后，在所有氯化核苷的实验中，除了 8ClA 和 8ClG 外，胰岛素刺激指数均显著下降。总之，这些结果表明，糖尿病炎症期间氯化核苷的形成增加可能会影响 β 细胞功能，并可能导致疾病进展。
