Cell iron status influences macrophage polarization

P. Gingivalis induce macrophage polarization by regulating hepcidin expression in chronic apical periodontitis

INTRODUCTION

Hepcidin, a central regulatory molecule of iron metabolism, is upregulated through the IL-6/STAT3 signaling pathway in inflammatory and infectious states, contributing to the pathogenesis of various diseases. In chronic apical periodontitis (CAP), Porphyromonas gingivalis (P. gingivalis) and its lipopolysaccharides (LPS) activate various immune responses in vivo, contributing to disease progression. This study evaluated the role and mechanism of hepcidin in P. gingivalis-induced bone tissue damage in CAP, focusing on its promotion of macrophage M1 polarization via the IL-6/STAT3 signaling pathway.

METHODS

We analyzed a GSE77459 dataset from the GEO database, containing data from inflammatory and normal dental pulp tissues. RT-qPCR and immunofluorescence staining were used to detect the expression of hepcidin in human CAP tissues and its relationship with macrophages. Mouse bone marrow derived macrophages (BMDMs) were cultured in vitro and stimulated with P. gingivalis LPS. The effects of Stattic on macrophage hepcidin expression, IL-6 expression, STAT3 phosphorylation, and macrophage polarization were detected by ELISA, western blotting, RT-qPCR, and flow cytometry, respectively.

RESULTS

Hepcidin expression in human inflammatory dental pulp tissues was upregulated via the IL-6/STAT3 pathway and correlated with macrophage polarization. Hepcidin-encoding genes were found to be highly expressed and primarily associated with M1 macrophages in CAP tissues. In vitro experiments revealed that P. gingivalis LPS stimulation induced macrophages to express hepcidin through the IL-6/STAT3 pathway and polarize to M1. Additionally, the IL-6/STAT3 pathway inhibitor Stattic suppressed these changes.

CONCLUSIONS

Our study demonstrates that in CAP, macrophages highly express hepcidin, which subsequently alters macrophage metabolism, regulates M1 polarization, and leads to bone tissue destruction.

Prognostic iron-metabolism signature robustly stratifies single-cell characteristics of hepatocellular carcinoma

Cancer immunotherapy has shown to be a promising method in treating hepatocellular carcinoma (HCC), but suboptimal responses in patients are attributed to cellular and molecular heterogeneity. Iron metabolism-related genes (IRGs) are important in maintaining immune system homeostasis and have the potential to help develop new strategies for HCC treatment. Herein, we constructed and validated the iron-metabolism gene prognostic index (IPX) using univariate Cox proportional hazards regression and LASSO Cox regression analysis, successfully categorizing HCC patients into two groups with distinct survival risks. Then, we performed single-sample gene set enrichment analysis, weighted correlation network analysis, gene ontology enrichment analysis, cellular lineage analysis, and SCENIC analysis to reveal the key determinants underlying the ability of this model based on bulk and single-cell transcriptomic data. We identified several driver transcription factors specifically activated in specific malignant cell sub-populations to contribute to the adverse survival outcomes in the IPX-high subgroup. Within the tumor microenvironment (TME), T cells displayed significant diversity in their cellular characteristics and experienced changes in their developmental paths within distinct clusters identified by IPX. Interestingly, the proportion of Treg cells was increased in the high-risk group compared with the low-risk group. These results suggest that iron-metabolism could be involved in reshaping the TME, thereby disrupting the cell cycle of immune cells. This study utilized IRGs to construct a novel and reliable model, which can be used to assess the prognosis of patients with HCC and further clarify the molecular mechanisms of IRGs in HCC at single-cell resolution.

Innate immune response to bone fracture healing

The field of osteoimmunology has primarily focused on fracture healing in isolated musculoskeletal injuries. The innate immune system is the initial response to fracture, with inflammatory macrophages, cytokines, and neutrophils arriving first at the fracture hematoma, followed by an anti-inflammatory phase to begin the process of new bone formation. This review aims to first discuss the current literature and knowledge gaps on the immune responses governing single fracture healing by encompassing the individual role of macrophages, neutrophils, cytokines, mesenchymal stem cells, bone cells, and other immune cells. This paper discusses the interactive effects of these cellular responses underscoring the field of osteoimmunology. The critical role of the metabolic environment in guiding the immune system properties will be highlighted along with some effective therapeutics for fracture healing in the context of osteoimmunology. However, compared to isolated fractures, which frequently heal well, long bone fractures in over 30 % of polytrauma patients exhibit impaired healing. Clinical evidence suggests there may be distinct physiologic and inflammatory pathways altered in polytrauma resulting in nonunion. Nonunion is associated with worse patient outcomes and increased societal healthcare costs. The dysregulated immunomodulatory/inflammatory response seen in polytrauma may lead to this increased nonunion rate. This paper will investigate the differences in immune response between isolated and polytrauma fractures. Finally, future directions for fracture studies are explored with consideration of the emerging roles of newly discovered immune cell functions in fracture healing, the existing challenges and conflicting results in the field, the translational potential of these studies in clinic, and the more complex nature of polytrauma fractures that can alter cell functions in different tissues.

Proteomic profiling of oleamide-mediated polarization in a primary human monocyte-derived tumor-associated macrophages (TAMs) model: a functional analysis

Background

Tumor-associated macrophages (TAMs) play a critical function in the development of tumors and are associated with protumor M2 phenotypes. Shifting TAMs towards antitumor M1 phenotypes holds promise for tumor immunotherapy. Oleamide, a primary fatty acid amide, has emerged as a potent anticancer and immunomodulatory compound. However, the regulatory effects of oleamide on TAM phenotypes remain unclear.

Methods

We used real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) techniques to study the influence of oleamide on primary human monocyte-derived TAM phenotypes, and we investigated the protein expression profiles based on mass spectrometry to analyze the effect of oleamide on macrophage polarization. Moreover, the advantageous binding scores between oleamide and these target candidate proteins are examined using molecular docking.

Results

Our study revealed that oleamide effectively suppressed the M2-like TAM phenotype by reducing interleukin (IL)-10 production and downregulating M2-like markers, including vascular endothelial growth factor A (VEGFA), MYC proto-oncogene, bHLH transcription factor (c-Myc), and mannose receptor C-type 1 (CD206). Moreover, the conditioned medium derived from oleamide-treated TAMs induces apoptosis of MDA-MB-231 breast cancer cells. Proteomic analysis identified 20 candidate up- and down-regulation proteins targeted by oleamide, showing modulation activity associated with the promotion of the M1-like phenotype. Furthermore, molecular docking demonstrated favorable binding scores between oleamide and these candidate proteins. Collectively, our findings suggest that oleamide exerts a potent antitumor effect by promoting the antitumor M1-like TAM phenotype. These novel insights provide valuable resources for further investigations into oleamide and macrophage polarization which inhibit the progression of breast cancer, which may provide insight into immunotherapeutic approaches for cancer.

Targeting and activation of macrophages in leishmaniasis. A focus on iron oxide nanoparticles

Macrophages play a pivotal role as host cells for Leishmania parasites, displaying a notable functional adaptability ranging from the proinflammatory, leishmanicidal M1 phenotype to the anti-inflammatory, parasite-permissive M2 phenotype. While macrophages can potentially eradicate amastigotes through appropriate activation, Leishmania employs diverse strategies to thwart this activation and redirect macrophages toward an M2 phenotype, facilitating its survival and replication. Additionally, a competition for iron between the two entities exits, as iron is vital for both and is also implicated in macrophage defensive oxidative mechanisms and modulation of their phenotype. This review explores the intricate interplay between macrophages, Leishmania, and iron. We focus the attention on the potential of iron oxide nanoparticles (IONPs) as a sort of immunotherapy to treat some leishmaniasis forms by reprogramming Leishmania-permissive M2 macrophages into antimicrobial M1 macrophages. Through the specific targeting of iron in macrophages, the use of IONPs emerges as a promising strategy to finely tune the parasite-host interaction, endowing macrophages with an augmented antimicrobial arsenal capable of efficiently eliminating these intrusive microbes.

The influence of iron nutrition on the development of intestine and immune cell divergency in neonatal pigs

BACKGROUND

Appropriate iron supplementation is essential for neonatal growth and development. However, there are few reports on the effects of iron overload on neonatal growth and immune homeostasis. Thus, the aim of this study was to investigate the effects of iron nutrition on neonatal growth and intestinal immunity by administering different levels of iron to neonatal pigs.

RESULTS

We found that iron deficiency and iron overload resulted in slow growth in neonatal pigs. Iron deficiency and iron overload led to down-regulation of jejunum intestinal barrier and antioxidant marker genes, and promoted CD8+ T cell differentiation in jejunum and mesenteric lymph nodes (MLN) of pigs, disrupting intestinal health. Moreover, iron levels altered serum iron and tissue iron status leading to disturbances in redox state, affecting host innate and adaptive immunity.

CONCLUSIONS

These findings emphasized the effect of iron nutrition on host health and elucidated the importance of iron in regulating redox state and immunity development. This study provided valuable insights into the regulation of redox state and immune function by iron metabolism in early life, thus contributing to the development of targeted interventions and nutritional strategies to optimize iron nutrition in neonates.

The differential impact of iron on ferroptosis, oxidative stress, and inflammatory reaction in head-kidney macrophages of yellow catfish (Pelteobagrus fulvidraco) with and without ammonia stress

Ammonia toxicity in fish is closely related to ferroptosis, oxidative stress, and inflammatory responses. Iron is an essential trace element that plays a key role in many biological processes for cells and organisms, including ferroptosis, oxidative stress response, and inflammation. This study aimed to investigate the effect of iron on indicators of fish exposed to ammonia, specifically on the three aspects mentioned above. The head kidney macrophages of yellow catfish were randomly assigned to one of four groups: CON (normal control), AM (0.046 mg L-1 total ammonia nitrogen), Fe (20 μg mL-1 FeSO4), and Fe + AM (20 μg mL-1 FeSO4, 0.046 mg L-1 total ammonia nitrogen). The cells were pretreated with FeSO4 for 6 h followed by ammonia for 24 h. The study found that iron supplementation led to an excessive accumulation of iron and ROS in macrophages, but it did not strongly induce ferroptosis, oxidative stress, or inflammatory responses. This was supported by a decrease in T-AOC, and the downregulation of SOD, as well as an increase in GSH levels and the upregulation of TFR1, CAT and Nrf2. Furthermore, the mRNA expression of HIF-1, p53 and the anti-inflammatory M2 macrophage marker Arg-1 were upregulated. The results also showed that iron supplementation increased the progression of some macrophages from early apoptosis to late apoptotic cells. However, the combined treatment of iron and ammonia resulted in a stronger intracellular ferroptosis, oxidative stress, and inflammatory reaction compared to either treatment alone. Additionally, there was a noticeable increase in necrotic cells in the Fe + AM and AM groups. These findings indicate that the biological functions of iron in macrophages of fish may vary inconsistently in the presence or absence of ammonia stress.

Nanomaterial-Based Repurposing of Macrophage Metabolism and Its Applications

Macrophage immunotherapy represents an emerging therapeutic approach aimed at modulating the immune response to alleviate disease symptoms. Nanomaterials (NMs) have been engineered to monitor macrophage metabolism, enabling the evaluation of disease progression and the replication of intricate physiological signal patterns. They achieve this either directly or by delivering regulatory signals, thereby mapping phenotype to effector functions through metabolic repurposing to customize macrophage fate for therapy. However, a comprehensive summary regarding NM-mediated macrophage visualization and coordinated metabolic rewiring to maintain phenotypic equilibrium is currently lacking. This review aims to address this gap by outlining recent advancements in NM-based metabolic immunotherapy. We initially explore the relationship between metabolism, polarization, and disease, before delving into recent NM innovations that visualize macrophage activity to elucidate disease onset and fine-tune its fate through metabolic remodeling for macrophage-centered immunotherapy. Finally, we discuss the prospects and challenges of NM-mediated metabolic immunotherapy, aiming to accelerate clinical translation. We anticipate that this review will serve as a valuable reference for researchers seeking to leverage novel metabolic intervention-matched immunomodulators in macrophages or other fields of immune engineering.

MiR-33a-5p in stored red blood cells regulates genes of innate immune response and promotes inflammation

BACKGROUND AND OBJECTIVES

Blood transfusion is a common therapeutic procedure in hospitalized patients. Red blood cell (RBC) units undergo various biochemical and morphological changes during storage (storage lesion). miRNAs have been studied intensively regarding cellular metabolic processes, but the effect of miRNAs on blood storage is not well defined.

MATERIALS AND METHODS

We performed bioinformatics analysis on the public data set of miRNA expression of RBC based on R language, and performed the Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis on the target genes of differentially expressed miRNA. The expression of miRNA differential genes in blood samples stored at different times was verified by qRT-PCR. Next, we used ELISA and qRT-PCR to verify the expression of IL-1β, IL-6, IL-12 and TNF-α in blood at day 1 and day 42. In addition, in vitro, we transfected macrophages with overexpressed miRNA, and the effects of overexpressed miRNA on macrophage polarization and the release of inflammatory factors were verified by flow cytometry and qRT-PCR and ELISA.

RESULTS

This study combined bioinformatics analysis and experiments to discover the differentially expressed miRNAs in long-term stored blood. The results showed that compared to fresh blood samples, the inflammatory factors were significantly doubled by ELISA, as well as the higher mRNA expression at 42 day. Experimentally verified that miR-33a-5p promoted the M1 type macrophage polarization and increased the release of related inflammatory factors through PPARα/ACC2/AMPK/CPT-1a axis regulation.

CONCLUSIONS

This study elucidates a potential mechanism of inflammatory factor accumulation in long-term stored blood, providing a theoretical basis and a potential target to prevent transfusion-related adverse reactions.

The Impact of the Combined Effect of Inhalation Anesthetics and Iron Dextran on Rats' Systemic Toxicity

Disruption of any stage of iron homeostasis, including uptake, utilization, efflux, and storage, can cause progressive damage to peripheral organs. The health hazards associated with occupational exposure to inhalation anesthetics (IA) in combination with chronic iron overload are not well documented. This study aimed to investigate changes in the concentration of essential metals in the peripheral organs of rats after iron overload in combination with IA. The aim was also to determine how iron overload in combination with IA affects tissue metal homeostasis, hepcidin-ferritin levels, and MMP levels according to physiological, functional, and tissue features. According to the obtained results, iron accumulation was most pronounced in the liver (19×), spleen (6.7×), lungs (3.1×), and kidneys (2.5×) compared to control. Iron accumulation is associated with elevated heavy metal levels and impaired essential metal concentrations due to oxidative stress (OS). Notably, the use of IA increases the iron overload toxicity, especially after Isoflurane exposure. The results show that the regulation of iron homeostasis is based on the interaction of hepcidin, ferritin, and other proteins regulated by inflammation, OS, free iron levels, erythropoiesis, and hypoxia. Long-term exposure to IA and iron leads to the development of numerous adaptation mechanisms in response to toxicity, OS, and inflammation. These adaptive mechanisms of iron regulation lead to the inhibition of MMP activity and reduction of oxidative stress, protecting the organism from possible damage.

Can iron chelators ameliorate viral infections?

The redox reactivity of iron is a double-edged sword for cell functions, being either essential or harmful depending on metal concentration and location. Deregulation of iron homeostasis is associated with several clinical conditions, including viral infections. Clinical studies as well as in silico, in vitro and in vivo models show direct effects of several viruses on iron levels. There is support for the strategy of iron chelation as an alternative therapy to inhibit infection and/or viral replication, on the rationale that iron is required for the synthesis of some viral proteins and genes. In addition, abnormal iron levels can affect signaling immune response. However, other studies report different effects of viral infections on iron homeostasis, depending on the class and genotype of the virus, therefore making it difficult to predict whether iron chelation would have any benefit. This review brings general aspects of the relationship between iron homeostasis and the nonspecific immune response to viral infections, along with its relevance to the progress or inhibition of the inflammatory process, in order to elucidate situations in which the use of iron chelators could be efficient as antivirals.

The dance of macrophage death: the interplay between the inevitable and the microenvironment

Macrophages are highly plastic cells ubiquitous in various tissues, where they perform diverse functions. They participate in the response to pathogen invasion and inflammation resolution following the immune response, as well as the maintenance of homeostasis and proper tissue functions. Macrophages are generally considered long-lived cells with relatively strong resistance to numerous cytotoxic factors. On the other hand, their death seems to be one of the principal mechanisms by which macrophages perform their physiological functions or can contribute to the development of certain diseases. In this review, we scrutinize three distinct pro-inflammatory programmed cell death pathways - pyroptosis, necroptosis, and ferroptosis - occurring in macrophages under specific circumstances, and explain how these cells appear to undergo dynamic yet not always final changes before ultimately dying. We achieve that by examining the interconnectivity of these cell death types, which in macrophages seem to create a coordinated and flexible system responding to the microenvironment. Finally, we discuss the complexity and consequences of pyroptotic, necroptotic, and ferroptotic pathway induction in macrophages under two pathological conditions - atherosclerosis and cancer. We summarize damage-associated molecular patterns (DAMPs) along with other microenvironmental factors, macrophage polarization states, associated mechanisms as well as general outcomes, as such a comprehensive look at these correlations may point out the proper methodologies and potential therapeutic approaches.

Lipopolysaccharide inhibits translation of iron chaperone PCBP1 to regulate inflammatory cytokine response in macrophage

Macrophages play a key role in maintaining systemic iron homeostasis and immunity. During pro-inflammatory stage macrophages retain iron due to the decrease of the unique iron exporter ferroportin. Increased cellular iron is sequestered in to storage protein ferritin by iron chaperone poly(rC)-binding protein 1 (PCBP1). However, the fate of PCBP1 and its interaction with ferritin in pro-inflammatory macrophages has not been studied so far. Here we report that PCBP1 protein level is down-regulated in lipopolysaccharide (LPS) treated macrophages. LPS did not alter PCBP1 mRNA and protein stability suggesting inhibition of translation as a mechanism of PCBP1 down-regulation that was confirmed by 35S-methionine incorporation assay. PCBP1 interacts with ferritin-H (Ft-H) subunit to load iron into ferritin. We detected a decreased interaction between PCBP1 and Ft-H after LPS-stimulation. As a result iron loading in to ferritin was affected with simultaneous increase in labile iron pool (LIP). Pre-treatment of cells with iron chelator dampened LPS-induced expression of TNF-α, IL-1β and IL-6 mRNA. Silencing of PCBP1 increased the magnitude of expression of these cytokines compared to control siRNA transfected LPS-treated macrophages. In contrast, overexpression of PCBP1 resulted a decrease in expression of these cytokines compared to vector transfected macrophages. Our results reveal a novel regulation of PCBP1 and its role in expression of cytokines in LPS-induced pro-inflammatory macrophages.

Low-Temperature Calcium Phosphate Ceramics Can Modulate Monocytes and Macrophages Inflammatory Response In Vitro

Creating bioactive materials for bone tissue regeneration and augmentation remains a pertinent challenge. One of the most promising and rapidly advancing approaches involves the use of low-temperature ceramics that closely mimic the natural composition of the extracellular matrix of native bone tissue, such as Hydroxyapatite (HAp) and its phase precursors (Dicalcium Phosphate Dihydrate-DCPD, Octacalcium Phosphate-OCP, etc.). However, despite significant scientific interest, the current knowledge and understanding remain limited regarding the impact of these ceramics not only on reparative histogenesis processes but also on the immunostimulation and initiation of local aseptic inflammation leading to material rejection. Using the stable cell models of monocyte-like (THP-1ATRA) and macrophage-like (THP-1PMA) cells under the conditions of LPS-induced model inflammation in vitro, the influence of DCPD, OCP, and HAp on cell viability, ROS and intracellular NO production, phagocytosis, and the secretion of pro-inflammatory cytokines was assessed. The results demonstrate that all investigated ceramic particles exhibit biological activity toward human macrophage and monocyte cells in vitro, potentially providing conditions necessary for bone tissue restoration/regeneration in the peri-implant environment in vivo. Among the studied ceramics, DCPD appears to be the most preferable for implantation in patients with latent inflammation or unpredictable immune status, as this ceramic had the most favorable overall impact on the investigated cellular models.

Advances in macrophage and T cell metabolic reprogramming and immunotherapy in the tumor microenvironment

Macrophages and T cells in the tumor microenvironment (TME) play an important role in tumorigenesis and progression. However, TME is also characterized by metabolic reprogramming, which may affect macrophage and metabolic activity of T cells and promote tumor escape. Immunotherapy is an approach to fight tumors by stimulating the immune system in the host, but requires support and modulation of cellular metabolism. In this process, the metabolic roles of macrophages and T cells become increasingly important, and their metabolic status and interactions play a critical role in the success of immunotherapy. Therefore, understanding the metabolic state of T cells and macrophages in the TME and the impact of metabolic reprogramming on tumor therapy will help optimize subsequent immunotherapy strategies.

Iron role paradox in nerve degeneration and regeneration

Iron accumulates in the neural tissue during peripheral nerve degeneration. Some studies have already been suggested that iron facilitates Wallerian degeneration (WD) events such as Schwann cell de-differentiation. On the other hand, intracellular iron levels remain elevated during nerve regeneration and gradually decrease. Iron enhances Schwann cell differentiation and axonal outgrowth. Therefore, there seems to be a paradox in the role of iron during nerve degeneration and regeneration. We explain this contradiction by suggesting that the increase in intracellular iron concentration during peripheral nerve degeneration is likely to prepare neural cells for the initiation of regeneration. Changes in iron levels are the result of changes in the expression of iron homeostasis proteins. In this review, we will first discuss the changes in the iron/iron homeostasis protein levels during peripheral nerve degeneration and regeneration and then explain how iron is related to nerve regeneration. This data may help better understand the mechanisms of peripheral nerve repair and find a solution to prevent or slow the progression of peripheral neuropathies.

Relation Between Tissue Iron Content and Polarization of Macrophages in Diabetic Ulcer and the Transitional Zone of Diabetic Ulcers with Major Amputation

Most diabetic lower-limb amputations probably result from combinations of contributing causes rather than from unitary causes. Iron-induced damage might modulate the development of chronic diabetes complications. In this study, the relationship between tissue iron levels and polarization of macrophages in induction of angiogenesis was investigated in diabetic ulcer samples and the transitional zone of diabetic ulcers. Patients with diabetic ulcers who underwent amputation were included. The transitional zone of diabetic ulcers, from the same diabetic patients, was used as a control group. After tissue preparation, Perls Prussian blue staining and immunohistochemistry for CD11c, CD163, and CD68 markers were done. Vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF), Tie2, and protein kinase B (also known as AKT) transcription of genes were measured by real-time polymerase chain reaction. For statistical analysis, we used independent samples t-test or its nonparametric equivalents, Mann-Whitney U test was used for quantitative variables, and chi-square (or Fisher's exact test) for qualitative variables. According to the results, the ratio of M2 to M1 macrophages was decreased in ulcers tissue compared to the transitional zone of diabetic ulcers. The expression of angiogenesis-related genes was increased due to hypoxia induction such as HIF and VEGF in ulcer tissue (P < .0001), but the expression of vascular stability-related genes such as Tie2 was decreased (P < .0001).In amputated diabetic ulcers, the polarization of macrophages is toward the classic type, but no connection was found in terms of tissue iron and help in the polarization of macrophages.

Djulis Hull Enhances the Efficacy of Ferric Citrate Supplementation via Restoring Normal Iron Efflux through the IL-6-Hepcidin-Ferroportin Pathway in High-Fat-Diet-Induced Obese Rats

Obesity-related functional iron disorder remains a major nutritional challenge. We evaluated the effects of djulis hull (DH) on iron metabolism in 50% high-fat-diet-induced obese rats supplemented with ferric citrate (2 g iron/kg diet) for 12 weeks. DH supplementation (5, 10, 15% dry weight/kg diet) significantly increased serum and hepatic iron but decreased appetite hormones, body weight, hepcidin, and liver inflammation (all p < 0.05). The Spearman correlation showed that appetite hormones were negatively associated with iron but positively correlated with liver hepcidin (all p < 0.05). A Western blot analysis showed that DH significantly downregulated hepatic hepcidin through the IL-6-JAK-STAT3 and enhanced ferroportin (Fpn) via the Keap1-Nrf2 and PHD2-HIF-2α. An in vitro study revealed that major bioactive compounds of DH, hexacosanol, and squalene suppressed LPS-induced IL-6 and hepcidin but enhanced Fpn expression in activated THP-1 cells. In conclusion, DH may exert nutraceutical properties for the treatment of functional iron disorder and restoration of iron efflux may have beneficial effects on weight control.

Lipocalin-2: A Nurturer of Tumor Progression and a Novel Candidate for Targeted Cancer Therapy

Within the tumor microenvironment (TME) exists a complex signaling network between cancer cells and stromal cells, which determines the fate of tumor progression. Hence, interfering with this signaling network forms the basis for cancer therapy. Yet, many types of cancer, in particular, solid tumors, are refractory to the currently used treatments, so there is an urgent need for novel molecular targets that could improve current anti-cancer therapeutic strategies. Lipocalin-2 (Lcn-2), a secreted siderophore-binding glycoprotein that regulates iron homeostasis, is highly upregulated in various cancer types. Due to its pleiotropic role in the crosstalk between cancer cells and stromal cells, favoring tumor progression, it could be considered as a novel biomarker for prognostic and therapeutic purposes. However, the exact signaling route by which Lcn-2 promotes tumorigenesis remains unknown, and Lcn-2-targeting moieties are largely uninvestigated. This review will (i) provide an overview on the role of Lcn-2 in orchestrating the TME at the level of iron homeostasis, macrophage polarization, extracellular matrix remodeling, and cell migration and survival, and (ii) discuss the potential of Lcn-2 as a promising novel drug target that should be pursued in future translational research.

Ferroptosis, autophagy, tumor and immunity

Ferroptosis was first proposed in 2012, a new form of cell death. Autophagy plays a crucial role in cell clearance and maintaining homeostasis. Autophagy is involved in the initial step of ferroptosis under the action of histone elements such as NCOA4, RAB7A, and BECN1. Ferroptosis and autophagy are involved in tumor progression, treatment, and drug resistance in the tumor microenvironment. In this review, we described the mechanisms of ferroptosis, autophagy, and tumor and immunotherapy, respectively, and emphasized the relationship between autophagy-related ferroptosis and tumor.

Thyroid hormones and minerals in immunocorrection of disorders in autoimmune thyroid diseases

Thyroid hormones and essential elements iodine (I), selenium (Se), iron (Fe), copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), etc. play an important role in the work of many organs and systems of the body, including the immune system and the thyroid gland, and a violation of their supply can be the cause of pathological changes in them. In pathology, the interaction between thyroid hormones (TG), minerals and the immune system is disturbed. The review of the literature examines the immunomodulatory role of TG, minerals, their properties, and their participation in the pathogenesis of autoimmune thyroid diseases (AITD). The study of the relationship between the excess or deficiency of minerals and AITD is described. The basis of the development of AITD - Hashimoto's thyroiditis (HT), Graves' disease (GD), Graves' ophthalmopathy (GO) is the loss of immune tolerance to thyroid antigens - thyroid peroxidase (TPO), thyroglobulin (Tg) and thyroid-stimulating hormone receptor (TSH-R). Immune-mediated mechanisms - production of autoantibodies to thyroid antigens and lymphocytic thyroid infiltration - are involved in the pathogenesis of AITD. Insufficiency of regulatory T cells (Treg) and regulatory B cells (Breg), imbalance between Th17-lymphocytes and Treg-lymphocytes, abnormal production of pro-inflammatory cytokines has a significant influence on the progression of AITD. With AITD, the balance between oxidants and antioxidants is disturbed and oxidative stress (OS) occurs. The lack of modern effective pharmacological therapy of AITD prompted us to consider the mechanisms of influence, possibilities of immunocorrection of pathogenetic factors using TG, micro/macronutrients. In order to develop a more effective treatment strategy, as well as approaches to prevention, a critical analysis of the ways of immunotherapeutic use of dietary supplements of I, Se, Zn, Mg and other minerals in AITD was carried out.

Myoglobin-derived iron causes wound enlargement and impaired regeneration in pressure injuries of muscle

The reasons for poor healing of pressure injuries are poorly understood. Vascular ulcers are worsened by extracellular release of hemoglobin, so we examined the impact of myoglobin (Mb) iron in murine muscle pressure injuries (mPI). Tests used Mb-knockout or treatment with deferoxamine iron chelator (DFO). Unlike acute injuries from cardiotoxin, mPI regenerated poorly with a lack of viable immune cells, persistence of dead tissue (necro-slough), and abnormal deposition of iron. However, Mb-knockout or DFO-treated mPI displayed a reversal of the pathology: decreased tissue death, decreased iron deposition, decrease in markers of oxidative damage, and higher numbers of intact immune cells. Subsequently, DFO treatment improved myofiber regeneration and morphology. We conclude that myoglobin iron contributes to tissue death in mPI. Remarkably, a large fraction of muscle death in untreated mPI occurred later than, and was preventable by, DFO treatment, even though treatment started 12 hr after pressure was removed. This demonstrates an opportunity for post-pressure prevention to salvage tissue viability.

Antioxidant and Immune-Related Implications of Minerals in COVID-19: A Possibility for Disease Prevention and Management

Since the coronavirus disease 2019 (COVID-19) pandemic appeared, both governments and the scientific community have focused their efforts on the search for prophylactic and therapeutic alternatives in order to reduce its effects. Vaccines against SARS-CoV-2 have been approved and administered, playing a key role in the overcoming of this situation. However, they have not reached the whole world population, and several doses will be needed in the future in order to successfully protect individuals. The disease is still here, so other strategies should be explored with the aim of supporting the immune system before and during the infection. An adequate diet is certainly associated with an optimal inflammatory and oxidative stress status, as poor levels of different nutrients could be related to altered immune responses and, consequently, an augmented susceptibility to infections and severe outcomes derived from them. Minerals exert a wide range of immune-modulatory, anti-inflammatory, antimicrobial, and antioxidant activities, which may be useful for fighting this illness. Although they cannot be considered as a definitive therapeutic solution, the available evidence to date, obtained from studies on similar respiratory diseases, might reflect the rationality of deeper investigations of the use of minerals during this pandemic.

Mitochondrial Dysfunction: At the Nexus between Alcohol-Associated Immunometabolic Dysregulation and Tissue Injury

Alcohol misuse, directly or indirectly as a result of its metabolism, negatively impacts most tissues, including four with critical roles in energy metabolism regulation: the liver, pancreas, adipose, and skeletal muscle. Mitochondria have long been studied for their biosynthetic roles, such as ATP synthesis and initiation of apoptosis. However, current research has provided evidence that mitochondria participate in myriad cellular processes, including immune activation, nutrient sensing in pancreatic β-cells, and skeletal muscle stem and progenitor cell differentiation. The literature indicates that alcohol impairs mitochondrial respiratory capacity, promoting reactive oxygen species (ROS) generation and disrupting mitochondrial dynamics, leading to dysfunctional mitochondria accumulation. As discussed in this review, mitochondrial dyshomeostasis emerges at a nexus between alcohol-disrupted cellular energy metabolism and tissue injury. Here, we highlight this link and focus on alcohol-mediated disruption of immunometabolism, which refers to two distinct, yet interrelated processes. Extrinsic immunometabolism involves processes whereby immune cells and their products influence cellular and/or tissue metabolism. Intrinsic immunometabolism describes immune cell fuel utilization and bioenergetics that affect intracellular processes. Alcohol-induced mitochondrial dysregulation negatively impacts immunometabolism in immune cells, contributing to tissue injury. This review will present the current state of literature, describing alcohol-mediated metabolic and immunometabolic dysregulation from a mitochondrial perspective.

The Chelating Ability of Plant Polyphenols Can Affect Iron Homeostasis and Gut Microbiota

In the past decades, many studies have widely examined the effects of dietary polyphenols on human health. Polyphenols are well known for their antioxidant properties and for their chelating abilities, by which they can be potentially employed in cases of pathological conditions, such as iron overload. In this review, we have highlighted the chelating abilities of polyphenols, which are due to their structural specific sites, and the differences for each class of polyphenols. We have also explored how the dietary polyphenols and their iron-binding abilities can be important in inflammatory/immunomodulatory responses, with a special focus on the involvement of macrophages and dendritic cells, and how they might contribute to reshape the gut microbiota into a healthy profile. This review also provides evidence that the axes “polyphenol–iron metabolism–inflammatory responses” and “polyphenol–iron availability–gut microbiota” have not been very well explored so far, and the need for further investigation to exploit such a potential to prevent or counteract pathological conditions.

Heat-Stable Enterotoxin Secretions Assessed via ICP-MS Reveal Iron-Mediated Regulation of Virulence in CFA/I- and CS6-Expressing ETEC Isolates

Enterotoxigenic Escherichia coli (ETEC) are a significant cause of childhood diarrhea in low-resource settings. ETEC are defined by the production of heat-stable enterotoxin (ST) and/or heat-labile enterotoxin (LT), which alter intracellular cyclic nucleotide signaling and cause the secretion of water and electrolytes into the intestinal lumen. ETEC take cues from chemicals (e.g., glycans, bile salts, and solutes) that may be liberated following enterotoxin activity to recognize entrance into the host. ETEC then alter the expression of surface adhesins called colonization factors (CFs) to attach to the intestinal epithelium, proliferate, and cause disease. Here, we used an in vivo model of oral ST intoxication to determine its impact on luminal ion concentrations via ICP-MS. We also used functional assays, including Western blots, qPCR, and toxin activity assays, to assess the impact of luminal ion flux on CF and toxin expression. Finally, we assessed ETEC strains with CFs CFA/I or CS6 in a streptomycin mouse model of ETEC colonization. ST causes rapid and significant increases in luminal chloride but significant decreases in luminal magnesium and iron. We confirmed that increased sodium chloride suppresses CFA/I production in ETEC H10407 but does not affect CS6 production in ETEC 214-4. CFA/I production in ETEC H10407 is increased when magnesium becomes limiting, although it does not affect CS6 production in ETEC 214-4. Iron restriction via deferoxamine induces CFA/I expression in ETEC H10407 but not CS6 expression in ETEC 214-4. We demonstrate that ST production is suppressed via iron restriction in H10407, 214-4, and over 50 other ETEC clinical isolates. Lastly, we demonstrate that the iron restriction of mice using oral deferoxamine pre-treatment extends the duration of ETEC H10407 (CFA/I⁺) fecal shedding while accelerating ETEC 214-4 (CS6⁺) fecal shedding. Combined, these data suggest that enterotoxins modulate luminal ion flux to influence ETEC virulence including toxin and CF production.

Marburg and Ebola Virus Infections Elicit a Complex, Muted Inflammatory State in Bats

The Marburg and Ebola filoviruses cause a severe, often fatal, disease in humans and nonhuman primates but have only subclinical effects in bats, including Egyptian rousettes, which are a natural reservoir of Marburg virus. A fundamental question is why these viruses are highly pathogenic in humans but fail to cause disease in bats. To address this question, we infected one cohort of Egyptian rousette bats with Marburg virus and another cohort with Ebola virus and harvested multiple tissues for mRNA expression analysis. While virus transcripts were found primarily in the liver, principal component analysis (PCA) revealed coordinated changes across multiple tissues. Gene signatures in kidney and liver pointed at induction of vasodilation, reduction in coagulation, and changes in the regulation of iron metabolism. Signatures of immune response detected in spleen and liver indicated a robust anti-inflammatory state signified by macrophages in the M2 state and an active T cell response. The evolutionary divergence between bats and humans of many responsive genes might provide a framework for understanding the differing outcomes upon infection by filoviruses. In this study, we outline multiple interconnected pathways that respond to infection by MARV and EBOV, providing insights into the complexity of the mechanisms that enable bats to resist the disease caused by filoviral infections. The results have the potential to aid in the development of new strategies to effectively mitigate and treat the disease caused by these viruses in humans.

Ironing out macrophages in atherosclerosis

<p indent="0mm">The most common cause of death worldwide is atherosclerosis and related cardiovascular disorders. Macrophages are important players in the pathogenesis of atherosclerosis and perform critical functions in iron homeostasis due to recycling iron by phagocytosis of senescent red blood cells and regulating iron availability in the tissue microenvironment. With the growth of research on the "iron hypothesis" of atherosclerosis, macrophage iron has gradually become a hotspot in the refined iron hypothesis. Macrophages with the M1, M2, M(Hb), Mox, and other phenotypes have been defined with different iron-handling capabilities related to the immune function and immunometabolism of macrophages, which influence the progression of atherosclerosis. In this review, we focus on macrophage iron and its effects on the development of atherosclerosis. We also cover the contradictory discoveries and propose a possible explanation. Finally, pharmaceutical modulation of macrophage iron is discussed as a promising target for atherosclerosis therapy.</p>.

Insulin resistance and adipose tissue inflammation induced by a high-fat diet are attenuated in the absence of hepcidin

Increased body iron stores and inflammation in adipose tissue have been implicated in the pathogenesis of insulin resistance (IR) and type 2 diabetes mellitus. However, the underlying basis of these associations is unclear. To attempt to investigate this, we studied the development of IR and associated inflammation in adipose tissue in the presence of increased body iron stores. Male hepcidin knock-out (Hamp1^-/-) mice, which have increased body iron stores, and wild-type (WT) mice were fed a high-fat diet (HFD) for 12 and 24 weeks. Development of IR and metabolic parameters linked to this, insulin signaling in various tissues, and inflammation and iron-related parameters in visceral adipose tissue were studied in these animals. HFD-feeding resulted in impaired glucose tolerance in both genotypes of mice. In response to the HFD for 24 weeks, Hamp1^-/- mice gained less body weight and developed less systemic IR than corresponding WT mice. This was associated with less lipid accumulation in the liver and decreased inflammation and lipolysis in the adipose tissue in the knock-out mice, than in the WT animals. Fewer macrophages infiltrated the adipose tissue in the knockout mice than in wild-type mice, with these macrophages exhibiting a predominantly anti-inflammatory (M2-like) phenotype and indirect evidence of a possible lowered intracellular iron content. The absence of hepcidin was thus associated with attenuated inflammation in the adipose tissue and increased whole-body insulin sensitivity, suggesting a role for it in these processes.

Binding to Iron Quercetin Complexes Increases the Antioxidant Capacity of the Major Birch Pollen Allergen Bet v 1 and Reduces Its Allergenicity

Bet v 1 is the major allergen in birch pollen to which up to 95% of patients sensitized to birch respond. As a member of the pathogenesis-related PR 10 family, its natural function is implicated in plant defense, with a member of the PR10 family being reported to be upregulated under iron deficiency. As such, we assessed the function of Bet v 1 to sequester iron and its immunomodulatory properties on human immune cells. Binding of Bet v 1 to iron quercetin complexes FeQ2 was determined in docking calculations and by spectroscopy. Serum IgE-binding to Bet v 1 with (holoBet v1) and without ligands (apoBet v 1) were assessed by ELISA, blocking experiments and Western Blot. Crosslinking-capacity of apo/holoBet v 1 were assessed on human mast cells and Arylhydrocarbon receptor (AhR) activation with the human reporter cellline AZ-AHR. Human PBMCs were stimulated and assessed for labile iron and phenotypic changes by flow cytometry. Bet v 1 bound to FeQ2 strongly with calculated Kd values of 1 nm surpassing affinities to quercetin alone nearly by a factor of 1000. Binding to FeQ2 masked IgE epitopes and decreased IgE binding up to 80% and impaired degranulation of sensitized human mast cells. Bet v 1 facilitated the shuttling of quercetin, which activated the anti-inflammatory AhR pathway and increased the labile iron pool of human monocytic cells. The increase of labile iron was associated with an anti-inflammatory phenotype in CD14+monocytes and downregulation of HLADR. To summarize, we reveal for the first time that FeQ2 binding reduces the allergenicity of Bet v 1 due to ligand masking, but also actively contributes anti-inflammatory stimuli to human monocytes, thereby fostering tolerance. Nourishing immune cells with complex iron may thus represent a promising antigen-independent immunotherapeutic approach to improve efficacy in allergen immunotherapy.

The Role of Macrophage Iron Overload and Ferroptosis in Atherosclerosis

Ferroptosis is a new type of cell death caused by iron-dependent lipid peroxidation. In recent years, it has been found that ferroptosis can promote the progression of atherosclerosis (AS). Macrophages have been proven to play multiple roles in the occurrence and development of AS. Iron is a necessary mineral that participates in different functions of macrophages under physiological conditions. But iron overload and ferroptosis in macrophages may promote the progression of AS. Herein, we summarize the role of iron overload and ferroptosis in macrophages in AS from the perspective of iron metabolism, and iron overload and ferroptosis are significant contributors to AS development.

Genetic regulation of iron homeostasis in sideropenic patients with mild COVID-19 disease under a new oral iron formulation: Lessons from a different perspective

Background

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) needs iron to replicate itself. Coronaviruses are able to upregulate Chop/Gadd153 and Arg1 genes, consequently leading to CD8 lymphocytes decrease, degradation of asparagine and decreased nitric oxide (NO), thus impairing immune response and antithrombotic functions. Little is known about regulation of genes involved in iron metabolism in paucisymptomatic patients with COVID-19 disease or in patients with iron deficiency treated with sucrosomial iron.

Methods

Whole blood was taken from the COVID-19 patients and from patients with sideropenic anemia, treated or not (control group) with iron supplementations. Enrolled patients were: affected by COVID19 under sucrosomal iron support (group A), affected by COVID-19 not under oral iron support (group B), iron deficiency not under treatment, not affected by COVID19 (control group). After RNA extraction and complementary DNA (cDNA) synthesis of Arg1, Hepcidin and Chop/Gadd153, gene expression from the 3 groups was measured by qRT-PCR. M2 macrophages were detected by cytofluorimetry using CD163 and CD14 markers.

Results

Forty patients with COVID-19 (group A), 20 patients with iron deficiency treated with sucrosomial iron (group B) and 20 patients with iron deficiency not under treatment (control group) were enrolled. In all the patients supported with oral sucrosomial iron, the gene expression of Chop, Arg1 and Hepcidin genes was lower than in sideropenic patients not supported with iron, M1 macrophages polarization and functional iron deficiency was also lower in group A and B, than observed in the control group.

Conclusions

New oral iron formulations, as sucrosomial iron, are able to influence the expression of genes like Chop and Arg1 and to influence M2 macrophage polarization mainly in the early phase of COVID-19 disease.

Iron Deposition and Ferroptosis in the Spleen in a Murine Model of Acute Radiation Syndrome

Total body irradiation (TBI) can result in death associated with hematopoietic insufficiency. Although radiation causes apoptosis of white blood cells, red blood cells (RBC) undergo hemolysis due to hemoglobin denaturation. RBC lysis post-irradiation results in the release of iron into the plasma, producing a secondary toxic event. We investigated radiation-induced iron in the spleens of mice following TBI and the effects of the radiation mitigator captopril. RBC and hematocrit were reduced ~7 days (nadir ~14 days) post-TBI. Prussian blue staining revealed increased splenic Fe3+ and altered expression of iron binding and transport proteins, determined by qPCR, western blotting, and immunohistochemistry. Captopril did not affect iron deposition in the spleen or modulate iron-binding proteins. Caspase-3 was activated after ~7–14 days, indicating apoptosis had occurred. We also identified markers of iron-dependent apoptosis known as ferroptosis. The p21/Waf1 accelerated senescence marker was not upregulated. Macrophage inflammation is an effect of TBI. We investigated the effects of radiation and Fe3+ on the J774A.1 murine macrophage cell line. Radiation induced p21/Waf1 and ferritin, but not caspase-3, after ~24 h. Radiation ± iron upregulated several markers of pro-inflammatory M1 polarization; radiation with iron also upregulated a marker of anti-inflammatory M2 polarization. Our data indicate that following TBI, iron accumulates in the spleen where it regulates iron-binding proteins and triggers apoptosis and possible ferroptosis.

Comparison of trace element (selenium, iron), electrolyte (calcium, sodium), and physical activity levels in COVID-19 patients before and after the treatment

OBJECTIVE

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), a worldwide health problem, is the cause of 2019 coronavirus disease. This study aimed to compare the trace element (selenium and iron), electrolyte (calcium and sodium), and physical activity levels of COVID-19 patients before and after COVID-19 treatment.

METHOD

This prospective study was conducted in patients diagnosed with COVID-19 (n = 15). Trace element (selenium and iron), electrolyte (calcium and sodium), and physical activity levels of the patients were compared before and after the treatment.

RESULT

Most of patients had selenium deficiency (86.7 %), iron deficiency (73.3 %), calcium deficiency (66.7 %) and sodium deficiency (46.7 %) before COVID-19 treatment. The most important improvements were seen in iron deficiency (from 73.3 % to 26.7 %) and sodium deficiency (from 46.7 % to 13.3 %) after the treatment. Selenium, iron, calcium, and sodium levels of the patients were significantly higher after the treatment (p < 0.05). The patients had low physical activity before and after COVID-19 treatment. In addition, no statistically significant difference was found in the comparison of physical activity levels (p > 0.05).

CONCLUSION

This study indicated that selenium, iron, calcium, and sodium levels and deficiencies might improve after treating patients with COVID-19. However, the results of this study showed that the physical activity levels of COVID-19 patients might remain stable and low throughout the treatment process.

Iron dyshomeostasis and time-course changes in iron-uptake systems and ferritin level in relation to pro-inflammatory microglia polarization in sepsis-induced encephalopathy

Encephalopathy is a frequent and lethal consequence of sepsis. Recently, a growing body of evidence has provided important insights into the role of iron dyshomeostasis in the context of inflammation. The molecular mechanisms underlying iron dyshomeostasis and its relationship with macrophage phenotypes are largely unknown. Here, we aimed to characterize the changes in iron-transporter and storage proteins and the microglia phenotype that occur during the course of sepsis, as well as their relationship with sepsis-induced encephalopathy. We used a cecal ligation and puncture (CLP) murine model that closely resembles sepsis-induced encephalopathy. Rats were subjected to CLP or sham laparotomy, then were neurologically assessed at 6 h, 24 h, and 3 days after sepsis induction. The serum and brain were collected for subsequent biochemical, histological, and immunohistochemical assessment. Here, an iron excess was observed at time points that followed the pro-inflammatory macrophage polarization in CLP-induced encephalopathy. Our results revealed that the upregulation of non-transferrin-bound iron uptake (NTBI) and ferritin reduction appeared to be partially responsible for the excess free iron detected within the brain tissues. We further demonstrated that the microglia were shifted toward the pro-inflammatory phenotype, leading to persistent neuro-inflammation and neuronal damage after CLP. Taken together, these findings led us to conclude that sepsis increased the susceptibility of the brain to the iron burden via the upregulation of NTBI and the reduction of ferritin, which was concomitantly and correlatively associated with dominance of pro-inflammatory microglia and could explain the neurological dysfunction observed during sepsis.

Dihydroartemisinin remodels macrophage into an M1 phenotype via ferroptosis-mediated DNA damage

Lung cancer recruits tumor-associated macrophages (TAMs) massively, whose predominantly pro-tumor M2 phenotype leads to immunosuppression. Dihydroartemisinin (DHA) has been proven to remodel TAM into an anti-tumor M1 phenotype at certain concentrations in the present study, which was hypothesized to facilitate anti-lung cancer immunotherapy. However, how DHA remodels the TAM phenotype has not yet been uncovered. Our previous work revealed that DHA could trigger ferroptosis in lung cancer cells, which may also be observed in TAM thereupon. Sequentially, in the current study, DHA was found to remodel TAM into the M1 phenotype in vitro and in vivo. Simultaneously, DHA was observed to trigger ferroptosis in TAM and cause the DNA damage response and NF-κB activation. Conversely, the DHA-induced DNA damage response and NF-κB activation in TAM were attenuated after the inhibition of ferroptosis in TAM using an inhibitor of ferroptosis. Importantly, a ferroptosis inhibitor could also abolish the DHA-induced phenotypic remodeling of TAM toward the M1 phenotype. In a nutshell, this work demonstrates that DHA-triggered ferroptosis of TAM results in DNA damage, which could activate downstream NF-κB to remodel TAM into an M1 phenotype, providing a novel strategy for anti-lung cancer immunotherapy. This study offers a novel strategy and theoretical basis for the use of traditional Chinese medicine monomers to regulate the anti-tumor immune response, as well as a new therapeutic target for TAM phenotype remodeling.

Iron Deficiency and Overload Modulate the Inflammatory Responses and Metabolism of Alveolar Macrophages

Alveolar macrophages (AM) are critical to defense against respiratory pathogens. This study evaluated cellular iron imbalance to immunometabolism in endotoxin-polarized porcine AMs (PAMs). PAMs collected from five 6-week-old pigs were treated with a basal media, iron chelator, or ferric ammonium citrate to maintain iron replete or induce iron deficiency or overload, respectively. After 24 h treatment, PAMs were challenged with saline or lipopolysaccharide (LPS) for 6 h. Cells were analyzed for gene, protein, and untargeted metabolome. Cytokines were determined in culture media. Data were assessed using two-way ANOVA. Treatments successfully induced iron deficiency and overload. The mRNA of DMT1 and ZIP14 was increased up to 300-fold by LPS, but unaffected by iron. Surprisingly, both iron deprivation and overload attenuated LPS-induced inflammation, showing less TNFα production and lower mRNA of pro- and anti-inflammatory cytokines than iron-replete PAMs. Forty-eight metabolites were altered by either or both main effects. LPS enhanced the glycolysis and polyol pathways. Iron deprivation disrupted the TCA cycle. Iron overload increased intracellular cholesterol. Interestingly, iron deprivation augmented, whereas iron overload diminished, LPS-induced itaconic acid production, which has anti-microbial and anti-inflammatory properties. Therefore, iron-deficient PAMs may be more resistant to intracellular pathogens which use PAMs as a conduit for infection.

Selenium Deficiency Aggravates Heat Stress Pneumonia in Chickens by Disrupting the M1/M2 Balance

Selenium (Se) is an essential trace element found in the body. Se deficiency and M1/M2 imbalance are closely related to inflammation. Heat stress can decrease immune function and cause inflammation. In order to investigate whether Se deficiency can aggravate pneumonia caused by heat stress and the role of M1/M2 imbalance in the occurrence of pneumonia, 100 AA broilers were divided into two groups and fed the conventional diet (0.2 mg/kg Se) and the Se-deficient diet (0.03 mg/kg Se). After 40 days of feeding, the normal feeding group was randomly divided into a control group and a heat stress group. At the same time, the Se-deficient diet feeding group was randomly divided into a low Se group and a low Se heat stress group, with 25 chickens in each group. The model was established by exposure at 40℃. Six hours later, broilers were euthanized, and their lung tissues were collected. Hematoxylin and eosin staining, immunofluorescence, quantitative real-time PCR, and western blotting were used to detect lung histopathological changes and the expression of M1/M2 markers, nuclear receptor-κB (NF-κB) pathway genes, and heat shock proteins. Meanwhile, the activity and content of oxidative stress-related indices were also detected. We found that the expression of interleukin-1β, interleukin-6, interleukin-12, and tumor necrosis factor-α was upregulated and the expression of interleukin-2, interleukin-10, and interferon-γ was downregulated. Immunofluorescence showed that the expression of CD16 was increased, the expression of CD163 was weakened, and the M1/M2 imbalance was present. In addition, the NF-κB pathway was activated by the increased expressions of heat shock proteins and oxidative stress. There was an increase in malondialdehyde, nitric oxide, and inducible nitric oxide synthase content, while the activity of total antioxidant capacity, glutathione peroxidase, catalase, and superoxide dismutase decreased, and the expression of NF-κB and cyclooxygenase-2 increased. These results suggest that low Se induces M1/M2 imbalance through oxidative stress activation of the NF-κB pathway and aggravates lung tissue inflammation caused by heat stress. This study offers a theoretical basis for exploring the pathogenesis of various kinds of inflammation induced by Se deficiency from the perspective of M1/M2 and provides a reference for the prevention of such diseases.

The Role of Microglia in Alzheimer’s Disease From the Perspective of Immune Inflammation and Iron Metabolism

Alzheimer’s disease (AD), the most common type of senile dementia, includes the complex pathogenesis of abnormal deposition of amyloid beta-protein (Aβ), phosphorylated tau (p-tau) and neuroimmune inflammatory. The neurodegenerative process of AD triggers microglial activation, and the overactivation of microglia produces a large number of neuroimmune inflammatory factors. Microglia dysfunction can lead to disturbances in iron metabolism and enhance iron-induced neuronal degeneration in AD, while elevated iron levels in brain areas affect microglia phenotype and function. In this manuscript, we firstly discuss the role of microglia in AD and then introduce the role of microglia in the immune-inflammatory pathology of AD. Their role in AD iron homeostasis is emphasized. Recent studies on microglia and ferroptosis in AD are also reviewed. It will help readers better understand the role of microglia in iron metabolism in AD, and provides a basis for better regulation of iron metabolism disorders in AD and the discovery of new potential therapeutic targets for AD.

The Role of Vascular-Immune Interactions in Modulating Chemotherapy Induced Neuropathic Pain

Chemotherapy causes sensory disturbances in cancer patients that results in neuropathies and pain. As cancer survivorships has dramatically increased over the past 10 years, pain management of these patients is becoming clinically more important. Current analgesic strategies are mainly ineffective and long-term use is associated with severe side effects. The issue being that common analgesic strategies are based on ubiquitous pain mediator pathways, so when applied to clinically diverse neuropathic pain and neurological conditions, are unsuccessful. This is principally due to the lack of understanding of the driving forces that lead to chemotherapy induced neuropathies. It is well documented that chemotherapy causes sensory neurodegeneration through axonal atrophy and intraepidermal fibre degeneration causing alterations in pain perception. Despite the neuropathological alterations associated with chemotherapy-induced neuropathic pain being extensively researched, underlying causes remain elusive. Resent evidence from patient and rodent studies have indicated a prominent inflammatory cell component in the peripheral sensory nervous system in effected areas post chemotherapeutic treatment. This is accompanied by modulation of auxiliary cells of the dorsal root ganglia sensory neurons such as activation of satellite glia and capillary dysfunction. The presence of a neuroinflammatory component was supported by transcriptomic analysis of dorsal root ganglia taken from mice treated with common chemotherapy agents. With key inflammatory mediators identified, having potent immunoregulatory effects that directly influences nociception. We aim to evaluate the current understanding of these immune-neuronal interactions across different cancer therapy drug classes. In the belief this may lead to better pain management approaches for cancer survivors.

Hepatic Macrophage Abundance and Phenotype in Aging and Liver Iron Accumulation

Liver macrophages serve important roles in iron homeostasis through phagocytosis of effete erythrocytes and the export of iron into the circulation. Conversely, intracellular iron can alter macrophage phenotype. Aging increases hepatic macrophage number and nonparenchymal iron, yet it is unknown whether age-related iron accumulation alters macrophage number or phenotype. To evaluate macrophages in a physiological model of iron loading that mimicked biological aging, young (6 mo) Fischer 344 rats were given one injection of iron dextran (15 mg/kg), and macrophage number and phenotype were evaluated via immunohistochemistry. A separate group of old (24 mo) rats was treated with 200 mg/kg deferoxamine every 12 h for 4 days. Iron administration to young rats resulted in iron concentrations that matched the values and pattern of tissue iron deposition observed in aged animals; however, iron did not alter macrophage number or phenotype. Aging resulted in significantly greater numbers of M1 (CD68⁺) and M2 (CD163⁺) macrophages in the liver, but neither macrophage number nor phenotype were affected by deferoxamine. Double-staining experiments demonstrated that both M1 (iNOS⁺) and M2 (CD163⁺) macrophages contained hemosiderin, suggesting that macrophages of both phenotypes stored iron. These results also suggest that age-related conditions other than iron excess are responsible for the accumulation of hepatic macrophages with aging.

Reprograming the immune niche for skin tissue regeneration - From cellular mechanisms to biomaterials applications

Despite the rapid development of therapeutic approaches for skin repair, chronic wounds such as diabetic foot ulcers remain an unaddressed problem that affects millions of people worldwide. Increasing evidence has revealed the crucial and diverse roles of the immune cells in the development and repair of the skin tissue, prompting new research to focus on further understanding and modulating the local immune niche for comprehensive, 'perfect' regeneration. In this review, we first introduce how different immunocytes and certain stromal cells involved in innate and adaptive immunity coordinate to maintain the immune niche and tissue homeostasis, with emphasis on their specific roles in normal and pathological wound healing. We then discuss novel engineering approaches - particularly biomaterials systems and cellular therapies - to target different players of the immune niche, with three major aims to i) overcome 'under-healing', ii) avoid 'over-healing', and iii) promote functional restoration, including appendage development. Finally, we highlight how these strategies strive to manage chronic wounds and achieve full structural and functional skin recovery by creating desirable 'soil' through modulating the immune microenvironment.

Genetically Predicted Circulating Concentrations of Micronutrients and COVID-19 Susceptibility and Severity: A Mendelian Randomization Study

Background

Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which since 2019 has caused over 5 million deaths to date. The pathogenicity of the virus is highly variable ranging from asymptomatic to fatal. Evidence from experimental and observational studies suggests that circulating micronutrients may affect COVID-19 outcomes.

Objectives

To complement and inform observational studies, we investigated the associations of genetically predicted concentrations of 12 micronutrients (β-carotene, calcium, copper, folate, iron, magnesium, phosphorus, selenium, vitamin B-6, vitamin B-12, vitamin D, and zinc) with SARS-CoV-2 infection risk and COVID-19 severity using Mendelian randomization (MR).

Methods

Two-sample MR was conducted using 87,870 individuals of European descent with a COVID-19 diagnosis and 2,210,804 controls from the COVID-19 host genetics initiative. Inverse variance-weighted MR analyses were performed with sensitivity analyses to assess the impact of potential violations of MR assumptions.

Results

Compared to the general population, nominally significant associations were noted for higher genetically predicted vitamin B-6 (Odds ratio per standard deviation [OR_SD]: 1.06; 95% confidence interval [CI]: 1.00, 1.13; p-value = 0.036) and lower magnesium concentrations (OR_SD: 0.33; 95%CI: 0.11, 0.96; P = 0.042) with COVID-19 infection risk. However, the association for magnesium was not consistent in some sensitivity analyses, and sensitivity analyses could not be performed for vitamin B-6 as only two genetic instruments were available. Genetically predicted levels of calcium, folate, β-carotene, copper, iron, vitamin B-12, vitamin D, selenium, phosphorus, or zinc were not associated with the outcomes from COVID-19 disease.

Conclusion

These results, though based only on genetically predicated circulating micronutrient concentrations, provide scant evidence for possible associations of micronutrients with COVID-19 outcomes.

Iron accumulation induces oxidative stress, while depressing inflammatory polarization in human iPSC-derived microglia

Iron accumulation in microglia has been observed in Alzheimer’s disease and other neurodegenerative disorders and is thought to contribute to disease progression through various mechanisms, including neuroinflammation. To study this interaction, we treated human induced pluripotent stem cell-derived microglia (iPSC-MG) with iron, in combination with inflammatory stimuli such as interferon gamma (IFN-γ) and amyloid β. Both IFN-γ and iron treatment increased labile iron levels, but only iron treatment led to a consistent increase of ferritin levels, reflecting long-term iron storage. Therefore, in iPSC-MG, ferritin appeared to be regulated by iron revels rather than inflammation. Further investigation showed that while IFN-γ induced pro-inflammatory activation, iron treatment dampened both classic pro- and anti-inflammatory activation on a transcriptomic level. Notably, iron-loaded microglia showed strong upregulation of cellular stress response pathways, the NRF2 pathway, and other oxidative stress pathways. Functionally, iPSC-MG exhibited altered phagocytosis and impaired mitochondrial metabolism following iron treatment. Collectively, these data suggest that in MG, in contrast to current hypotheses, iron treatment does not result in pro-inflammatory activation, but rather dampens it and induces oxidative stress.

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In iPSC-microglia, iron rather than inflammatory activation induces ferritin expression

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Excessive iron dampens both classic pro- and anti-inflammatory activation

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Iron uptake leads to upregulation of NRF2 and other oxidative stress pathways

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Phagocytosis and mitochondrial metabolism are altered following iron uptake

Crosstalk between Heme Oxygenase-1 and Iron Metabolism in Macrophages: Implications for the Modulation of Inflammation and Immunity

Heme oxygenase-1 (HO-1) is an enzyme that catalyzes the degradation of heme, releasing equimolar amounts of carbon monoxide (CO), biliverdin (BV), and iron. The anti-inflammatory and antioxidant properties of HO-1 activity are conferred in part by the release of CO and BV and are extensively characterized. However, iron constitutes an important product of HO-1 activity involved in the regulation of several cellular biological processes. The macrophage-mediated recycling of heme molecules, in particular those contained in hemoglobin, constitutes the major mechanism through which living organisms acquire iron. This process is finely regulated by the activities of HO-1 and of the iron exporter protein ferroportin. The expression of both proteins can be induced or suppressed in response to pro- and anti-inflammatory stimuli in macrophages from different tissues, which alters the intracellular iron concentrations of these cells. As we discuss in this review article, changes in intracellular iron levels play important roles in the regulation of cellular oxidation reactions as well as in the transcriptional and translational regulation of the expression of proteins related to inflammation and immune responses, and therefore, iron metabolism represents a potential target for the development of novel therapeutic strategies focused on the modulation of immunity and inflammation.

Effects of Volatile Anaesthetics and Iron Dextran on Chronic Inflammation and Antioxidant Defense System in Rats

Iron, as an essential microelement, is involved in cell proliferation, metabolism, and differentiation. It also modulates the fate and function of macrophages in hematopoiesis and macrophage-mediated inflammatory responses. On the other hand, anesthetics can affect the inflammatory process by modulating the response to stress or the functions of immune cells. The aim of this paper is to understand how excessive iron intake alters physiological, functional characteristics of peripheral tissues and whether different anesthetics can alter cell metabolism regarding oxidative stress (OS) and inflammation through regulation of macrophage polarization. Y59 rats were injected intraperitoneally with iron dextran solution at a dose of 50 mg/kg or were exposed to inhaled anesthetics sevoflurane and isoflurane and their combination for 28 days every other day. The results show that the use of anesthetics reduces the rat’s organ weight and increases OS in peripheral tissues, leading to M1 macrophage polarization. Excessive iron intake leads to increased OS, inflammation, and an increased ratio of IL-12/IL-10 cytokines to the M1 macrophage phenotype. Iron, in combination with sevoflurane, has a protective effect in tissues showing the M2 phenotype of macrophages. The combination of iron dextran and isoflurane in rats leads to an increase in the erythropoiesis process made possible through the induction of hypoxia.

A PET-based fluorescent probe for monitoring labile Fe(II) pools in macrophage activations and ferroptosis

A fluorescent probe (COU-LIP-1) for monitoring labile Fe(II) pools (LIP) with high selectivity and sensitivity was developed utilizing coumarin 343 as the fluorophore and 3-nitrophenylazanyl ester as both the reactive group and the fluorescence quenching group. Fe(II)-induced reductive cleavage of the N-O bond results in a turn-on response via a photo-induced photon transfer (PET) mechanism. The probe was applied for monitoring labile iron(II) changes in M1 and M2a macrophage activations and also erastin-induced ferroptosis, providing a powerful tool for selectively sensing LIP under both physiological and stressed conditions.

Excess iron promotes emergence of foamy macrophages that overexpress ferritin in the lungs of silicosis patients

Background and objective

Inhalation of high concentrations of respirable crystalline silica (RCS) can lead to silicosis. RCS contains varying levels of iron, which can cause oxidative stress and stimulate ferritin production. This study evaluated iron‐related and inflammatory markers in control and silicosis patients.

Methods

A cohort of stone benchtop industry workers (n = 18) were radiologically classified by disease severity into simple or complicated silicosis. Peripheral blood and bronchoalveolar lavage (BAL) were collected to measure iron, ferritin, C‐reactive protein, serum amyloid A and serum silicon levels. Ferritin subunit expression in BAL and transbronchial biopsies was analysed by reverse transcription quantitative PCR. Lipid accumulation in BAL macrophages was assessed by Oil Red O staining.

Results

Serum iron levels were significantly elevated in patients with silicosis, with a strong positive association with serum ferritin levels. In contrast, markers of systemic inflammation were not increased in silicosis patients. Serum silicon levels were significantly elevated in complicated disease. BAL macrophages from silicosis patients were morphologically consistent with lipid‐laden foamy macrophages. Ferritin light chain (FTL) mRNA expression in BAL macrophages was also significantly elevated in simple silicosis patients and correlated with systemic ferritin.

Conclusion

Our findings suggest that elevated iron levels during the early phases of silicosis increase FTL expression in BAL macrophages, which drives elevated BAL and serum ferritin levels. Excess iron and ferritin were also associated with the emergence of a foamy BAL macrophage phenotype. Ferritin may represent an early disease marker for silicosis, where increased levels are independent of inflammation and may contribute to fibrotic lung remodelling.

Silicosis is an aggressive and incurable lung disease. In this study, serum iron levels were increased in silicosis patients, and these levels were strongly associated with serum ferritin levels. Lipid‐laden bronchoalveolar lavage macrophages were identified as a major source of ferritin, whereas markers of inflammation were not increased.

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Ferric Ammonium Citrate Upregulates PD-L1 Expression through Generation of Reactive Oxygen Species

Iron plays an important role in macrophage polarization by altering metabolic and redox status. However, the impact of iron on the immune status of macrophages is still controversial. In this study, we report that ferric ammonium citrate (FAC) upregulates PD-L1 expression in macrophages. FAC not only altered the phenotype of macrophages but also led to enriching immune-modulatory T cell subsets. Since iron is known to be a constituent of coenzymes facilitating metabolic processes in mitochondria, we examined the metabolic status of FAC-overloaded macrophages by measuring the oxygen consumption rate (OCR) and the represented coenzyme, aconitase. In addition to enhancement of metabolic processes, FAC accelerated the Fenton reaction in macrophages, which also contributed to the facilitation of oxygen consumption. We reasoned that the enhancement of the OCR leads to the production of reactive oxygen species (ROS), which are directly linked to PD-L1 induction. Using ferrostatin, rotenone, and N-acetyl-L-cysteine, we confirmed that metabolic and redox regulation is responsible for FAC-mediated PD-L1 expression. Furthermore, we suggested that FAC-induced ROS production may explain FAC-mediated pro- and anti-inflammatory responses in macrophages. These findings may extend our understanding of regulating iron concentration during immune checkpoint therapy in cancer patients.