Department of Cardiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China.
Department of Respiratory Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China.
Mol Med Rep. 2020 Nov;22(5):4003-4016. doi: 10.3892/mmr.2020.11495. Epub 2020 Sep 7.
Cardiac fibrosis is a major pathological manifestation of diabetic cardiomyopathy, which is a leading cause of mortality in patients with diabetes. MicroRNA (miR)‑155 is upregulated in cardiomyocytes in cardiac fibrosis, and the aim of the present study was to investigate if the inhibition of miR‑155 was able to ameliorate cardiac fibrosis by targeting the nuclear factor erythroid‑2‑related factor 2 (Nrf2)/heme oxygenase‑1 (HO‑1) signaling pathway. H9C2 rat cardiomyocytes were cultured with high glucose (HG; 30 mM) to establish an in vitro cardiac fibrosis model that mimicked diabetic conditions; a miR‑155 inhibitor and a miR‑155 mimic were transfected into H9C2 cells. Following HG treatment, H9C2 cells exhibited increased expression levels of miR‑155 and the fibrosis markers collagen I and α‑smooth muscle actin (α‑SMA). In addition, the expression levels of endonuclear Nrf2 and HO‑1 were decreased, but the expression level of cytoplasmic Nrf2 was increased. Moreover, oxidative stress, mitochondrial damage and cell apoptosis were significantly increased, as indicated by elevated reactive oxygen species, malonaldehyde and monomeric JC‑1 expression levels. In addition, superoxide dismutase expression was attenuated and there was an increased expression level of released cytochrome‑c following HG treatment. Furthermore, it was demonstrated that expression levels of Bcl‑2 and uncleaved Poly (ADP‑ribose) polymerase were downregulated, whereas Bax, cleaved caspase‑3 and caspase‑9 were upregulated after HG treatment. However, the miR‑155 inhibitor significantly restored Nrf2 and HO‑1 expression levels, and reduced oxidative stress levels, the extent of mitochondrial damage and the number of cells undergoing apoptosis. Additionally, the miR‑155 inhibitor significantly reversed the expression levels of collagen I and α‑SMA, thus ameliorating fibrosis. Furthermore, the knockdown of Nrf2 reversed the above effects induced by the miR‑155 inhibitor. In conclusion, the miR‑155 inhibitor may ameliorate diabetic cardiac fibrosis by reducing the accumulation of oxidative stress‑related molecules, and preventing mitochondrial damage and cardiomyocyte apoptosis by enhancing the Nrf2/HO‑1 signaling pathway. This mechanism may facilitate the development of novel targets to prevent cardiac fibrosis in patients with diabetes.
心肌纤维化是糖尿病心肌病的主要病理表现，也是糖尿病患者死亡的主要原因。miR-155 在心肌纤维化的心肌细胞中上调，本研究旨在探讨抑制 miR-155 是否能够通过靶向核因子红细胞 2 相关因子 2 (Nrf2)/血红素加氧酶 1 (HO-1) 信号通路来改善心肌纤维化。将大鼠 H9C2 心肌细胞用高糖（30mM）培养以建立模拟糖尿病条件的体外心肌纤维化模型；将 miR-155 抑制剂和 miR-155 模拟物转染至 H9C2 细胞。经 HG 处理后，H9C2 细胞中 miR-155 和纤维化标志物胶原 I 和α-平滑肌肌动蛋白（α-SMA）的表达水平升高。此外，核内 Nrf2 和 HO-1 的表达水平降低，而细胞质 Nrf2 的表达水平升高。此外，氧化应激、线粒体损伤和细胞凋亡显著增加，表现为活性氧、丙二醛和单体 JC-1 表达水平升高。此外，HG 处理后超氧化物歧化酶表达减弱，细胞色素 c 释放表达水平升高。此外，HG 处理后还表明 Bcl-2 和未切割的多聚（ADP-核糖）聚合酶表达水平下调，而 Bax、切割的 caspase-3 和 caspase-9 表达水平上调。然而，miR-155 抑制剂可显著恢复 Nrf2 和 HO-1 的表达水平，并降低氧化应激水平、线粒体损伤程度和细胞凋亡数量。此外，miR-155 抑制剂可显著逆转胶原 I 和 α-SMA 的表达水平，从而改善纤维化。此外，Nrf2 的敲低逆转了 miR-155 抑制剂诱导的上述作用。综上所述，miR-155 抑制剂可能通过减少与氧化应激相关分子的积累，通过增强 Nrf2/HO-1 信号通路来预防线粒体损伤和心肌细胞凋亡，从而改善糖尿病性心肌纤维化。该机制可能有助于开发预防糖尿病患者心肌纤维化的新靶点。
