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Polarized activation affects iron metabolism in macrophages

LI Yun-Qin1, LIANG Li2,3, , GAN Zhen-Shun2,3,

1Analysis Center of Agrobiology and Environmental Science, Zhejiang University, Hangzhou 310058, China;2Key Laboratory of Animal Molecular Nutrition, Ministry of Education, Zhejiang University, Hangzhou 310058, China;3College of Animal Science, Zhejiang University, Hangzhou 310058, China

Abstract

The aim of this study was to investigate the effects of polarization program on the ability of macrophages to regulate iron metabolism. M1 and M2 macrophages were propagated in vitro from porcine alveolar macrophages 3D4/2 and polarized by cytokines. The 3D4/2 macrophages were treated with 20 ng/mL interferon gamma (IFN-γ) and 10 ng/mL interleukin-4 (IL-4) combined with 10 ng/mL macrophage colony-stimulating factor (M-CSF) to induce polarization to M1 and M2, respectively. After incubation for 24 h, the expression levels of inflammatory factors and iron-metabolism genes were determined using real-time qPCR, Western bot and 

immunofluorescence. The M1/M2 macrophages culture media supernatant was collected and used to treat porcine intestinal epithelial cells IPEC-J2. The proliferation ability of IPEC-J2 was detected using CCK-8 assay kit. Following exogenous addition of ammonium ferric citrate (FAC) to M1/M2 macrophages, the phagocytic function of macrophages was detected using fluorescein isothiocyanate-dextran (FITC-dextran) and flow cytometry. The results showed that, compared with control, M1 macrophages had higher mRNA levels of iron storage proteins (ferritin heavy and light polypeptide, i.e. FtH and FtL), hepcidin and lipocalin-2, as well as iron content. Moreover, iron enhanced the ability of M1 macrophages to phagocytize FITC-dextran. There was no significant change in these mRNA expression levels in M2 macrophages, but the mRNA expression levels of ferroportin and transferrin receptor were up-regulated. In addition, the conditioned media supernatant from M2 macrophages promoted cell proliferation of IPEC-J2. These findings indicate that M1 macrophages tend to lock iron in the cell and reduce extracellular iron content, thereby inhibiting the proliferation of extracellular bacteria. While M2 macrophages tend to excrete iron, which contributes to the proliferation of surrounding cells and thus promotes tissue repair.


Key words: Iron metabolism; M1 macrophage; M2 macrophage

Received: 2020-06-02  Accepted: 2020-08-21

Corresponding author: DU Hua-Hua  E-mail: huahuadu@zju.edu.cn,huahuadu@zju.edu.cn

Citing This Article:

LI Yun-Qin, LIANG Li, GAN Zhen-Shun, TANG Xue-You, DU Hua-Hua. Polarized activation affects iron metabolism in macrophages. Acta Physiol Sin 2021; 73 (2): 244-252 (in Chinese with English abstract).