Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark.
Division of Nephrology, Department of Internal Medicine III, 60323 Goethe-University Frankfurt, Frankfurt am Main, Germany.
Int J Mol Sci. 2020 Mar 16;21(6):2038. doi: 10.3390/ijms21062038.
Lipocalin-2 (Lcn-2) is rapidly upregulated in macrophages after renal tubular injury and acts as renoprotective and pro-regenerative agent. Lcn-2 possesses the ability to bind and transport iron with high affinity. Therefore, the present study focuses on the decisive role of the Lcn-2 iron-load for its pro-regenerative function. Primary mouse tubular epithelial cells were isolated from kidney tissue of wildtype mice and incubated with 5μM Cisplatin for 24h to induce injury. Bone marrow-derived macrophages of wildtype and Lcn-2 mice were isolated and polarized with IL-10 towards an anti-inflammatory, iron-release phenotype. Their supernatants as well as recombinant iron-loaded holo-Lcn-2 was used for stimulation of Cisplatin-injured tubular epithelial cells. Incubation of tubular epithelial cells with wildtype supernatants resulted in less damage and induced cellular proliferation, whereas in absence of Lcn-2 no protective effect was observed. Epithelial integrity as well as cellular proliferation showed a clear protection upon rescue experiments applying holo-Lcn-2. Notably, we detected a positive correlation between total iron amounts in tubular epithelial cells and cellular proliferation, which, in turn, reinforced the assumed link between availability of Lcn-2-bound iron and recovery. We hypothesize that macrophage-released Lcn-2-bound iron is provided to tubular epithelial cells during toxic cell damage, whereby injury is limited and recovery is favored.
脂质运载蛋白 2（Lcn-2）在肾小管损伤后迅速在巨噬细胞中上调，并作为肾保护和促进再生的剂。Lcn-2 具有与铁结合并高亲和力运输铁的能力。因此，本研究重点关注 Lcn-2 铁负荷对其促再生功能的决定性作用。从野生型小鼠的肾脏组织中分离出原代小鼠肾小管上皮细胞，并在 5μM 顺铂孵育 24 小时以诱导损伤。分离出野生型和 Lcn-2 小鼠的骨髓衍生巨噬细胞，并通过白细胞介素 10 极化，使其呈现抗炎、释放铁的表型。用顺铂损伤的肾小管上皮细胞刺激它们的上清液以及重组铁负载的完整 Lcn-2。用野生型上清液孵育肾小管上皮细胞可减轻损伤并诱导细胞增殖，而在没有 Lcn-2 的情况下则没有观察到保护作用。用完整 Lcn-2 进行挽救实验表明，上皮完整性和细胞增殖均受到明显保护。值得注意的是，我们检测到肾小管上皮细胞中铁的总量与细胞增殖之间存在正相关，这反过来又强化了 Lcn-2 结合铁的可用性与恢复之间的假定联系。我们假设，在毒性细胞损伤期间，巨噬细胞释放的与 Lcn-2 结合的铁被提供给肾小管上皮细胞，从而限制损伤并有利于恢复。
