Department of Medicine, The University of Washington, Seattle, WA, USA.
Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
Nephrol Dial Transplant. 2021 Feb 20;36(3):465-474. doi: 10.1093/ndt/gfaa348.
Iron sucrose (FeS) administration induces a state of renal preconditioning, protecting against selected forms of acute kidney injury (AKI). Recent evidence suggests that recombinant hepcidin also mitigates acute renal damage. Hence the goals of this study were to determine whether a new proprietary FeS formulation ('RBT-3') can acutely activate the hepcidin (HAMP1) gene in humans, raising plasma and renal hepcidin concentrations; assess whether the kidney participates in this posited RBT-3-hepcidin generation response; test whether RBT-3 can mitigate a clinically relevant AKI model (experimental cisplatin toxicity) and explore whether mechanisms in addition to hepcidin generation are operative in RBT-3's cytoprotective effects.
Healthy human volunteers (n = 9) and subjects with Stages 3-4 CKD (n = 9) received 120, 240 or 360 mg of RBT-3 (intravenously over 2 h). Plasma and urine samples were collected and assayed for hepcidin levels (0-72 h post-RBT-3 injection). In complementary mouse experiments, RBT-3 effects on hepatic versus renal hepcidin (HAMP1) messenger RNA (mRNA) and protein levels were compared. RBT-3's impact on the mouse Nrf2 pathway and on experimental cisplatin nephrotoxicity was assessed. Direct effects of exogenous hepcidin on in vivo and in vitro (HK-2 cells) cisplatin toxicity were also tested.
RBT-3 induced rapid, dose-dependent and comparable plasma hepcidin increases in both healthy volunteers and chronic kidney disease subjects (∼15 times baseline within 24 h). Human kidney hepcidin exposure was confirmed by 4-fold urinary hepcidin increases. RBT-3 up-regulated mouse hepcidin mRNA, but much more so in kidney (>25 times) versus liver (∼2 times). RBT-3 also activated kidney Nrf2 [increased Nrf2 nuclear binding; increased Nrf2-responsive gene mRNAs: heme oxygenase-1, sulfiredoxin-1, glutamate-cysteine ligase catalytic subunit and NAD(P)H quinone dehydrogenase 1]. RBT-3 preconditioning (18 h time lapse) markedly attenuated experimental cisplatin nephrotoxicity (∼50% blood urea nitrogen/creatinine decrements), in part by reducing renal cisplatin uptake by 40%. Exogenous hepcidin (without RBT-3) treatment conferred protection against mild in vivo (but not in vitro) cisplatin toxicity.
RBT-3 acutely and dramatically up-regulates cytoprotective hepcidin production, increasing renal hepcidin levels. However, additional cytoprotective mechanisms are activated by RBT-3 (e.g. Nrf2 activation; reduced cisplatin uptake). Thus RBT-3-induced preconditioning likely confers renal resistance to cisplatin via an interplay of multiple cytoprotective activities.
铁蔗糖（FeS）的给药会诱导肾脏预适应状态，从而预防某些形式的急性肾损伤（AKI）。最近的证据表明，重组铁调素也能减轻急性肾损伤。因此，本研究的目的是确定一种新的专有 FeS 制剂（'RBT-3'）是否可以在人类中急性激活铁调素（HAMP1）基因，提高血浆和肾脏铁调素浓度；评估肾脏是否参与这种假定的 RBT-3-铁调素生成反应；测试 RBT-3 是否可以减轻临床相关的 AKI 模型（实验性顺铂毒性），并探索除铁调素生成外，RBT-3 的细胞保护作用是否还通过其他机制发挥作用。
健康志愿者（n=9）和 3-4 期慢性肾脏病患者（n=9）接受 120、240 或 360mg 的 RBT-3（静脉注射，持续 2 小时）。收集血浆和尿液样本，并测定铁调素水平（RBT-3 注射后 0-72 小时）。在补充的小鼠实验中，比较了 RBT-3 对肝脏和肾脏铁调素（HAMP1）信使 RNA（mRNA）和蛋白质水平的影响。评估了 RBT-3 对小鼠 Nrf2 途径和实验性顺铂肾毒性的影响。还测试了外源性铁调素对体内和体外（HK-2 细胞）顺铂毒性的直接影响。
RBT-3 在健康志愿者和慢性肾脏病患者中均诱导快速、剂量依赖性和可比的血浆铁调素升高（24 小时内增加约 15 倍基线）。通过尿液中 4 倍的铁调素增加来确认人肾脏铁调素暴露。RBT-3 上调了小鼠铁调素 mRNA，但在肾脏中的上调幅度更大（>25 倍），而在肝脏中（约 2 倍）。RBT-3 还激活了肾脏 Nrf2 [增加 Nrf2 核结合；增加 Nrf2 反应性基因 mRNAs：血红素加氧酶-1、硫氧还蛋白-1、谷氨酸-半胱氨酸连接酶催化亚基和 NAD（P）H 醌脱氢酶 1]。RBT-3 预处理（18 小时延迟）显著减轻实验性顺铂肾毒性（约 50%的血尿素氮/肌酐降低），部分原因是通过减少 40%的肾脏顺铂摄取。外源性铁调素（无 RBT-3）治疗可预防轻度体内（但非体外）顺铂毒性。
RBT-3 可急性和显著地上调细胞保护铁调素的产生，增加肾脏铁调素水平。然而，RBT-3 还激活了其他细胞保护机制（例如 Nrf2 激活；减少顺铂摄取）。因此，RBT-3 诱导的预适应可能通过多种细胞保护活性的相互作用赋予肾脏对顺铂的抗性。
