Xiao Xia, Yeoh Beng San, Saha Piu, Olvera Rodrigo Aguilera, Singh Vishal, Vijay-Kumar Matam
Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
Department of Medicine, The Pennsylvania State University Medical Center, Hershey, PA, 17033, USA.
Biometals. 2016 Jun;29(3):451-65. doi: 10.1007/s10534-016-9925-5. Epub 2016 Mar 23.
Iron is an essential transition metal ion for virtually all aerobic organisms, yet its dysregulation (iron overload or anemia) is a harbinger of many pathologic conditions. Hence, iron homeostasis is tightly regulated to prevent the generation of catalytic iron (CI) which can damage cellular biomolecules. In this study, we investigated the role of iron-binding/trafficking innate immune protein, lipocalin 2 (Lcn2, aka siderocalin) on iron and CI homeostasis using Lcn2 knockout (KO) mice and their WT littermates. Administration of iron either systemically or via dietary intake strikingly upregulated Lcn2 in the serum, urine, feces, and liver of WT mice. However, similarly-treated Lcn2KO mice displayed elevated CI, augmented lipid peroxidation and other indices of organ damage markers, implicating that Lcn2 responses may be protective against iron-induced toxicity. Herein, we also show a negative association between serum Lcn2 and CI in the murine model of dextran sodium sulfate (DSS)-induced colitis. The inability of DSS-treated Lcn2KO mice to elicit hypoferremic response to acute colitis, implicates the involvement of Lcn2 in iron homeostasis during inflammation. Using bone marrow chimeras, we further show that Lcn2 derived from both immune and non-immune cells participates in CI regulation. Remarkably, exogenous rec-Lcn2 supplementation suppressed CI levels in Lcn2KO serum and urine. Collectively, our results suggest that Lcn2 may facilitate hypoferremia, suppress CI generation and prevent iron-mediated adverse effects.
铁是几乎所有需氧生物必需的过渡金属离子,然而其调节异常(铁过载或贫血)是许多病理状况的先兆。因此,铁稳态受到严格调控,以防止能损伤细胞生物分子的催化铁(CI)的产生。在本研究中,我们使用脂联素2(Lcn2,又名铁调素)基因敲除(KO)小鼠及其野生型同窝小鼠,研究了铁结合/转运固有免疫蛋白Lcn2对铁和CI稳态的作用。通过全身给药或饮食摄入铁显著上调了野生型小鼠血清、尿液、粪便和肝脏中的Lcn2。然而,同样处理的Lcn2基因敲除小鼠显示CI升高、脂质过氧化增加以及其他器官损伤标志物指标升高,这表明Lcn2的反应可能对铁诱导的毒性具有保护作用。在此,我们还在葡聚糖硫酸钠(DSS)诱导的结肠炎小鼠模型中显示血清Lcn2与CI之间呈负相关。DSS处理的Lcn2基因敲除小鼠无法对急性结肠炎引发低铁血症反应,这表明Lcn2在炎症期间参与铁稳态。使用骨髓嵌合体,我们进一步表明来自免疫细胞和非免疫细胞的Lcn2都参与CI调节。值得注意的是,外源性重组Lcn2补充剂可降低Lcn2基因敲除小鼠血清和尿液中的CI水平。总体而言,我们的结果表明Lcn2可能促进低铁血症,抑制CI生成并预防铁介导的不良反应。
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