Intermedin通过SIRT1介导抑制NOX4/ROS轴减轻慢性间歇性缺氧诱导的肾纤维化

文献信息

中文摘要

背景： 阻塞性睡眠呼吸暂停低通气综合征（OSAHS）以慢性间歇性缺氧（CIH）为特征，是慢性肾脏病（CKD）的独立危险因素；其潜在机制可能涉及氧化应激。本研究采用互补的体内和体外模型，探讨小分子抗氧化肽intermedin（IMD）在CIH诱导的肾纤维化中的作用。方法：将全身IMD敲除（IMD-/-）小鼠和野生型（IMD+/+）同窝小鼠暴露于CIH 12周。将人近端肾小管上皮细胞（HK-2）暴露于CIH 48小时，并给予或不给予外源性IMD。在IMD-/-小鼠中进行腺相关病毒血清型9（AAV9）介导的NADPH氧化酶4（NOX4）短发夹RNA（shRNA）敲低，并在HK-2细胞中使用选择性sirtuin 1（SIRT1）抑制剂EX527。结果：我们发现，CIH在小鼠肾脏和HK-2细胞中均上调IMD及其受体（降钙素受体样受体[CLR]和受体活性修饰蛋白[RAMPs]）。IMD缺乏加重了CIH诱导的肾功能障碍、纤维化、氧化应激、凋亡和炎症，而外源性IMD减轻了这些病理变化。机制上，IMD上调SIRT1并抑制NOX4表达。在IMD-/-小鼠中敲低NOX4部分逆转了加重的肾损伤和纤维化。在HK-2细胞中，EX527消除了IMD诱导的NOX4下调和其对CIH诱导的活性氧（ROS）产生、凋亡和胶原沉积的保护作用，表明IMD以SIRT1依赖的方式抑制NOX4。结论：总之，这些发现表明IMD通过上调SIRT1并随后抑制NOX4/ROS轴来减轻CIH诱导的肾纤维化。本研究将IMD确定为一种内源性肾脏保护因子，并提示SIRT1/NOX4/ROS通路可作为OSAHS相关肾病的潜在治疗靶点。

英文摘要

Obstructive sleep apnea hypopnea syndrome (OSAHS) is characterized by chronic intermittent hypoxia (CIH) and is an independent risk factor for chronic kidney disease (CKD); the underlying mechanism may involve oxidative stress. This study investigated the role of intermedin (IMD), a small antioxidant peptide, in CIH-induced renal fibrosis using complementary in vivo and in vitro models. Systemic IMD knockout (IMD-/-) mice and wild-type (IMD+/+) littermates were subjected to CIH for 12 weeks. Human proximal tubular epithelial cell (HK-2) was exposed to CIH for 48 h with or without exogenous IMD. Adeno-associated virus serotype 9 (AAV9)-mediated short hairpin RNA (shRNA) knockdown of NADPH oxidase 4 (NOX4) was performed in IMD-/- mice, and the selective sirtuin 1 (SIRT1) inhibitor EX527 was used in HK-2 cells. We showed that CIH upregulated IMD and its receptors (calcitonin receptor-like receptor [CLR] and receptor activity-modifying proteins [RAMPs]) in both mouse kidneys and HK-2 cells. IMD deficiency exacerbated CIH-induced renal dysfunction, fibrosis, oxidative stress, apoptosis, and inflammation, whereas exogenous IMD attenuated these pathological changes. Mechanistically, IMD upregulated SIRT1 and suppressed NOX4 expression. NOX4 knockdown in IMD-/- mice partially reversed the aggravated renal injury and fibrosis. In HK-2 cells, EX527 abolished the IMD-induced downregulation of NOX4 and its protective effects against CIH-induced reactive oxygen species (ROS) production, apoptosis, and collagen deposition, indicating that IMD inhibits NOX4 in a SIRT1-dependent manner. Collectively, these findings demonstrate that IMD mitigates CIH-induced renal fibrosis by upregulating SIRT1 and subsequently inhibiting the NOX4/ROS axis. This study identifies IMD as an endogenous renoprotective factor and suggests the SIRT1/NOX4/ROS pathway as a potential therapeutic target for OSAHS-associated nephropathy.