Sow Fatoumata B, Florence William C, Satoskar Abhay R, Schlesinger Larry S, Zwilling Bruce S, Lafuse William P
Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
J Leukoc Biol. 2007 Oct;82(4):934-45. doi: 10.1189/jlb.0407216. Epub 2007 Jul 3.
Hepcidin is an antimicrobial peptide produced by the liver in response to inflammatory stimuli and iron overload. Hepcidin regulates iron homeostasis by mediating the degradation of the iron export protein ferroportin 1, thereby inhibiting iron absorption from the small intestine and release of iron from macrophages. Here, we examined the expression of hepcidin in macrophages infected with the intracellular pathogens Mycobacterium avium and Mycobacterium tuberculosis. Stimulation of the mouse RAW264.7 macrophage cell line and mouse bone marrow-derived macrophages with mycobacteria and IFN-gamma synergistically induced high levels of hepcidin mRNA and protein. Similar results were obtained using the human THP-1 monocytic cell line. Stimulation of macrophages with the inflammatory cytokines IL-6 and IL-beta did not induce hepcidin mRNA expression. Iron loading inhibited hepcidin mRNA expression induced by IFN-gamma and M. avium, and iron chelation increased hepcidin mRNA expression. Intracellular protein levels and secretion of hepcidin were determined by a competitive chemiluminescence ELISA. Stimulation of RAW264.7 cells with IFN-gamma and M. tuberculosis induced intracellular expression and secretion of hepcidin. Furthermore, confocal microscopy analyses showed that hepcidin localized to the mycobacteria-containing phagosomes. As hepcidin has been shown to possess direct antimicrobial activity, we investigated its activity against M. tuberculosis. We found that hepcidin inhibited M. tuberculosis growth in vitro and caused structural damage to the mycobacteria. In summary, our data show for the first time that hepcidin localizes to the phagosome of infected, IFN-gamma-activated cells and has antimycobacterial activity.
铁调素是肝脏在炎症刺激和铁过载时产生的一种抗菌肽。铁调素通过介导铁输出蛋白铁转运蛋白1的降解来调节铁稳态，从而抑制小肠对铁的吸收以及巨噬细胞释放铁。在此，我们检测了细胞内病原体鸟分枝杆菌和结核分枝杆菌感染的巨噬细胞中铁调素的表达。用分枝杆菌和γ干扰素刺激小鼠RAW264.7巨噬细胞系和小鼠骨髓来源的巨噬细胞，协同诱导了高水平的铁调素mRNA和蛋白质。使用人THP-1单核细胞系也获得了类似结果。用炎性细胞因子白细胞介素-6和白细胞介素-β刺激巨噬细胞未诱导铁调素mRNA表达。铁负荷抑制了γ干扰素和鸟分枝杆菌诱导的铁调素mRNA表达，而铁螯合增加了铁调素mRNA表达。通过竞争性化学发光酶联免疫吸附测定法测定铁调素的细胞内蛋白水平和分泌情况。用γ干扰素和结核分枝杆菌刺激RAW264.7细胞诱导了铁调素的细胞内表达和分泌。此外，共聚焦显微镜分析表明铁调素定位于含分枝杆菌的吞噬体。由于铁调素已被证明具有直接抗菌活性，我们研究了其对结核分枝杆菌的活性。我们发现铁调素在体外抑制结核分枝杆菌生长并对分枝杆菌造成结构损伤
