Iron overloaded polarizes macrophage to proinflammation phenotype through ROS/acetyl‐p53 pathway

Abstract

PurposeMacrophages play critical roles in inflammation and wound healing and can be divided into two subtypes: classically activated (M1) and alternatively activated (M2) macrophages. Macrophages also play important roles in regulating iron homeostasis, and intracellular iron accumulation induces M1‐type macrophage polarization which provides a potential approach to tumor immunotherapy through M2 tumor‐associated macrophage repolarization. However, the mechanisms underlying iron‐induced M1 polarization remain unclear.MethodsWestern blotting, qRT‐PCR, and flow cytometry were used to detect the polarization indexes in RAW 264.7 murine macrophages treated with iron, and Western bloting and qRT‐PCR were used to detect p21 expression. The compound 2,7‐dichlorofluorescein diacetate was used to measure reactive oxygen species (ROS) levels in macrophages after iron or N‐acetyl‐l‐cysteine (NAC) treatment. The p300/CREB‐binding protein (CBP) inhibitor C646 was used to inhibit p53 acetylation, and Western bloting, qRT‐PCR, and immunofluorescence were used to detect p53 expression and acetylation. BALB/c mice were subcutaneously injected with H22 hepatoma cells, and macrophage polarization status was investigated after tail intravenous injection of iron. Immunohistochemical staining was used to evaluate the protein expression of cluster of differentiation 86 (CD86) and EGF‐like module‐containing mucin‐like hormone receptor‐like 1 (F4/80) in the subcutaneous tumors.ResultsIron overload induced M1 polarization by increasing ROS production and inducing p53 acetylation in RAW cells, and reduction in ROS levels by NAC repressed M1 polarization and p53 acetylation. Inhibition of acetyl‐p53 by a p300/CBP inhibitor prevented M1 polarization and inhibited p21 expression. These results showed that high ROS levels induced by iron overload polarized macrophages to the M1 subtype by enhancing p300/CBP acetyltransferase activity and promoting p53 acetylation.

Major Depression in Children with β-Thalassemia Major is Strongly Associated with the Number of Blood Transfusions, Iron Overload and Increased Levels of Interleukin-1β

“…These findings are also in agreement with recent findings suggesting a double-faced response of cell-mediated immunity in β-TM patients, namely that T cells show a stimulated phenotype while in fact their activity is suppressed [65]. As described in the Introduction, IO is associated with immune-inflammatory responses, M1 macrophage polarization and increased TNF-α expression due to IO and antigenic stimulation induced by chronic transfusion therapy [18][19][20] The fourth major finding of this study is that MDD in β-TM is characterized by increased levels of IL-1β and M1 activation as compared with β-TM patients without MDD and that the M1/CIRS ratio was significantly increased in β-TM with MDD versus controls while those with β-TM without MDD occupied an intermediate position. Moreover, the CDI score was significantly associated with both pro-inflammatory cytokines, the M1 macrophage activation index and the M1/CIRS ratio.…”

“…Intracellular iron accumulation may induce M1 macrophage polarization [19] and increased inflammatory gene expression [20].…”

Tissue Iron Promotes Wound Repair via M2 Macrophage Polarization and the Chemokine (C-C Motif) Ligands 17 and 22

“…Heme uptake by macrophages in the damaged spinal cord promotes M1driven inflammation in mice, 38 whereas iron sequestration induced an M1 phenotype in raw246.7 macrophages. 39 It has even been suggested that sustained, iron-induced, proinflammatory macrophages may contribute to delayed healing by triggering fibroblast senescence. 40,41 On the contrary, in atherosclerotic plaques, hemoglobinhaptoglobin complexes shifted macrophages toward an M2 state both in vivo (higher CD163) and in vitro (increased IL-10 and IL-1RA 42 ).…”

Bipolar Tumor-Associated Macrophages in Ovarian Cancer as Targets for Therapy

“…This suggests that increasing miR-216a through indirect means could be exploited therapeutically, in ovarian cancer. Reactive oxygen species (ROS) polarize macrophages to M1-like phenotypes [ 43 , 44 ]. HOXA9 polarizes peritoneal macrophages to M2-like phenotypes [ 45 ].…”