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The iron and inflammation homeostasis are closely coupled, forming an integrated functional unit under physiological conditions. "Iron transport balance" has become the key mechanism to maintain iron homeostasis through bidirectional regulation of iron uptake and release and dynamic management of transmembrane concentration. It is also the physiological basis for the inflammatory balance between promotion and resolution. Under pathological conditions, represented by inflammatory bowel disease (IBD), disturbed iron transportation was highly involved in almost every step of inflammatory diseases. Therefore, the iron transporting rebalancing provides the mechanistic basis and effective approach for the normalization of inflammatory microenvironment. Macrophage is the key regulator of inflammation homeostasis and determinant for iron transport balance. Unfortunately, the current clinical transformation based on iron transport balance theory has still been insufficient. Sometimes, this strategy even showed high complexity and contradiction, severely restricting its clinical application. By summarizing the theoretical research progress of iron transport balance, especially its relevance to macrophage phenotypic polarization, this review aims to explore the therapeutic value in inflammation intervention by targeting iron transporting balance. This review will provide the necessary knowledge and hints for the research and development of candidate drugs in treating inflammatory diseases.
RESUMEN
Background Lead exposure induces microglial cell death, of which the mechanism is unclear. Ferroptosis is a new death form and its role in microglia death has not been reported. Objective To investigate the role of ferroptosis in microglia following lead exposure in order to provide a theoretical basis for the mechanism of lead neurotoxicity. Methods Microglial cell line BV-2 cells were co-cultured with 0, 10, 20 and 40 μmol·L−1 lead acetate for 24 h. The 40 μmol·L−1 lead acetate group with iron chelator (DFO) was named the 40+DFO group. Changes in BV-2 cell morphology after lead exposure were observed under an inverted microscope; tissue iron kit and glutathione kit were used to detect intracellular iron and glutathione (GSH) respectively; flow cytometry was applied to detect lipid reactive oxygen species (lipid ROS) immunofluorescence intensity. Western blotting and qPCR were adopted to detect the expressions of glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), transferrin receptor 1 (TFR-1), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1) protein and mRNA. Results Compared with the control group, the number of BV-2 cells decreased with increasing doses of lead and the cells showed a large, round amoeboid shape. The intracellular levels of iron of BV-2 cells were (1.08±0.04), (1.29±0.03), and (1.72±0.10) mg·g−1 (calculated by protein, thereafter) in the 10, 20, and 40 μmol·L−1 lead acetate groups, respectively, significantly higher than that in the control group (P<0.05), and the intracellular level of iron in the 40+DFO group, (1.34±0.10) mg·g−1, was lower than that in the 40 μmol·L−1 lead acetate group, (1.72±0.03) mg·g−1 (P<0.05). Compared with the control group, the TFR-1 and DMT1 protein and mRNA expressions were increased in BV-2 cells in the 10, 20, 40 μmol·L−1 lead acetate groups (P<0.05), especially in the 40 μmol·L−1 lead acetate group; the FPN1 protein expression did not change significantly, but the FPN1 mRNA expressions in BV-2 cells in the 10, 20, 40 μmol·L−1 lead acetate groups were significantly decreased (P<0.05). Compared with the control group, the intracellular GSH level decreased and the lipid ROS content increased in all three lead acetate groups; compared with the 40 μmol·L−1 lead acetate group, the GSH level increased by 12.30% and the lipid ROS content decreased by 13.00% in the 40+DFO group (P<0.05). The expressions of GPX4 protein were reduced to 50.00%, 35.00%, and 17.00% of that of the control group in the 10, 20, and 40 μmol·L−1 lead acetate groups respectively, while the expressions of GPX4 mRNA were also significantly reduced; the expressions of SLC7A11 protein and mRNA in the 20 and 40 μmol·L−1 lead acetate groups were lower than that in the control group, with the most significant decrease in the 40 μmol·L−1 lead acetate group (P<0.05). Conclusion Lead exposure could induce ferroptosis in BV-2 cells, in which iron transport imbalance and oxidative damage might be involved.
RESUMEN
Biological denitrification is the most widely used technology for nitrate removal in wastewater treatment. Conventional denitrification requires long hydraulic retention time, and the nitrate removal efficiency in winter is low due to the low temperature. Therefore, it is expected to develop new approaches to enhance the denitrification process. In this paper, the effect of adding different concentrations of Fe₃O₄ nanoparticles on the denitrification catalyzed by Pseudomonas stutzeri was investigated. The maximum specific degradation rate of nitrate nitrogen improved from 18.0 h⁻¹ to 23.7 h⁻¹ when the concentration of Fe₃O₄ increased from 0 mg/L to 4 000 mg/L. Total proteins and intracellular iron content also increased along with increasing the concentration of Fe₃O₄. RT-qPCR and label-free proteomics analyses showed that the relative expression level of denitrifying genes napA, narJ, nirB, norR, nosZ of P. stutzeri increased by 55.7%, 24.9%, 24.5%, 36.5%, 120% upon addition of Fe₃O₄, and that of denitrifying reductase Nap, Nar, Nir, Nor, Nos increased by 85.0%, 147%, 16.5%, 47.1%, 95.9%, respectively. No significant difference was observed on the relative expression level of denitrifying genes and denitrifying reductases between the bacteria suspended and the bacteria adhered to Fe₃O₄. Interestingly, the relative expression level of electron transfer proteins of bacteria adhered to Fe₃O₄ was higher than that of the bacteria suspended. The results indicated that Fe₃O₄ promoted cell growth and metabolism through direct contact with bacteria, thereby improving the denitrification. These findings may provide theoretical support for the development of enhanced denitrification.