Phagocytosis, oxidative burst, and produced reactive species are affected by iron deficiency anemia and anemia of chronic diseases in elderly

A closer look at the role of iron in glioblastoma

Glioblastoma (GBM) is among the deadliest malignancies facing modern oncology. While our understanding of certain aspects of GBM biology has significantly increased over the last decade, other aspects, such as the role of bioactive metals in GBM progression, remain understudied. Iron is the most abundant transition metal found within the earth's crust and plays an intricate role in human physiology owing to its ability to participate in oxidation-reduction reactions. The importance of iron homeostasis in human physiology is apparent when examining the clinical consequences of iron deficiency or iron overload. Despite this, the role of iron in GBM progression has not been well described. Here, we review and synthesize the existing literature examining iron's role in GBM progression and patient outcomes, as well as provide a survey of iron's effects on the major cell types found within the GBM microenvironment at the molecular and cellular level. Iron represents an accessible target given the availability of already approved iron supplements and chelators. Improving our understanding of iron's role in GBM biology may pave the way for iron-modulating approaches to improve patient outcomes.

Plasma iron controls neutrophil production and function

Low plasma iron (hypoferremia) induced by hepcidin is a conserved inflammatory response that protects against infections but inhibits erythropoiesis. How hypoferremia influences leukocytogenesis is unclear. Using proteomic data, we predicted that neutrophil production would be profoundly more iron-demanding than generation of other white blood cell types. Accordingly in mice, hepcidin-mediated hypoferremia substantially reduced numbers of granulocytes but not monocytes, lymphocytes, or dendritic cells. Neutrophil rebound after anti-Gr-1-induced neutropenia was blunted during hypoferremia but was rescued by supplemental iron. Similarly, hypoferremia markedly inhibited pharmacologically stimulated granulopoiesis mediated by granulocyte colony-stimulating factor and inflammation-induced accumulation of neutrophils in the spleen and peritoneal cavity. Furthermore, hypoferremia specifically altered neutrophil effector functions, suppressing antibacterial mechanisms but enhancing mitochondrial reactive oxygen species-dependent NETosis associated with chronic inflammation. Notably, antagonizing endogenous hepcidin during acute inflammation enhanced production of neutrophils. We propose plasma iron modulates the profile of innate immunity by controlling monocyte-to-neutrophil ratio and neutrophil activity in a therapeutically targetable system.

A Bioinformatics-Assisted Review on Iron Metabolism and Immune System to Identify Potential Biomarkers of Exercise Stress-Induced Immunosuppression

The immune function is closely related to iron (Fe) homeostasis and allostasis. The aim of this bioinformatics-assisted review was twofold; (i) to update the current knowledge of Fe metabolism and its relationship to the immune system, and (ii) to perform a prediction analysis of regulatory network hubs that might serve as potential biomarkers during stress-induced immunosuppression. Several literature and bioinformatics databases/repositories were utilized to review Fe metabolism and complement the molecular description of prioritized proteins. The Search Tool for the Retrieval of Interacting Genes (STRING) was used to build a protein-protein interactions network for subsequent network topology analysis. Importantly, Fe is a sensitive double-edged sword where two extremes of its nutritional status may have harmful effects on innate and adaptive immunity. We identified clearly connected important hubs that belong to two clusters: (i) presentation of peptide antigens to the immune system with the involvement of redox reactions of Fe, heme, and Fe trafficking/transport; and (ii) ubiquitination, endocytosis, and degradation processes of proteins related to Fe metabolism in immune cells (e.g., macrophages). The identified potential biomarkers were in agreement with the current experimental evidence, are included in several immunological/biomarkers databases, and/or are emerging genetic markers for different stressful conditions. Although further validation is warranted, this hybrid method (human-machine collaboration) to extract meaningful biological applications using available data in literature and bioinformatics tools should be highlighted.

Iron excess affects release of neutrophil extracellular traps and reactive oxygen species but does not influence other functions of neutrophils

Neutrophils apply several antimicrobial strategies including degranulation, phagocytosis, the generation of reactive oxygen species (ROS) and the release of neutrophil extracellular traps (NETs) to fight pathogens. Iron is considered to be an invaluable constituent of host immune defense and plays a dual role in immunity. It is a well-known component of antimicrobial proteins and is a necessary microelement for pathogen survival. The aim of this study was to broaden the knowledge regarding the impact of iron on the function of neutrophils. Neutrophils from healthy blood donors and patients with mild iron-deficiency anemia and HL-60 cells differentiated toward granulocyte-like cells were incubated with Fe²⁺ , Fe³⁺ or holo-transferrin (holo-Tf). Moreover, we isolated murine neutrophils of HFE gene knockout (KO) mice and mice fed iron-deficient, iron-equivalent and high-iron diets. We analyzed the release of NETs, phagocytosis, degranulation of azurophilic granules, ROS release, bactericidal activity of granulocytes against Escherichia coli and neutrophil elastase (NE) activity. We show that holo-Tf inhibits the release of NETs stimulated by phorbol 12-myristate 13-acetate by inhibiting NE activity. Studies performed in mice models reveal that iron overload inhibits the release of NETs and ROS production in neutrophils isolated from HFE KO mice and mice fed a high-iron diet. No impact of a low-iron diet on neutrophil phagocytosis, ROS production or release of NETs was observed. Our study underscores the physiological significance of iron in neutrophil function, specifically in the release of NETs.

Flipside of the Coin: Iron Deficiency and Colorectal Cancer

Iron deficiency, with or without anemia, is the most frequent hematological manifestation in individuals with cancer, and is especially common in patients with colorectal cancer. Iron is a vital micronutrient that plays an essential role in many biological functions, in the context of which it has been found to be intimately linked to cancer biology. To date, however, whereas a large number of studies have comprehensively investigated and reviewed the effects of excess iron on cancer initiation and progression, potential interrelations of iron deficiency with cancer have been largely neglected and are not well-defined. Emerging evidence indicates that reduced iron intake and low systemic iron levels are associated with the pathogenesis of colorectal cancer, suggesting that optimal iron intake must be carefully balanced to avoid both iron deficiency and iron excess. Since iron is vital in the maintenance of immunological functions, insufficient iron availability may enhance oncogenicity by impairing immunosurveillance for neoplastic changes and potentially altering the tumor immune microenvironment. Data from clinical studies support these concepts, showing that iron deficiency is associated with inferior outcomes and reduced response to therapy in patients with colorectal cancer. Here, we elucidate cancer-related effects of iron deficiency, examine preclinical and clinical evidence of its role in tumorigenesis, cancer progression and treatment response. and highlight the importance of adequate iron supplementation to limit these outcomes.

Biological and Immunological Aspects of Iron Deficiency Anemia in Cancer Development: A Narrative Review

Iron Deficiency Anemia (IDA) is a universal health problem and a risk factor for the development of cancer. IDA changes the microenvironment of the human body by affecting both the biological and immunological systems. It increases DNA damage and genomic instability by different mechanisms. IDA is one of the leading causes of the imbalance between different antioxidant enzymes as well as enzymes involved in DNA damage and DNA repair systems of the body. It can affect the biogenesis/expression of microRNAs. IDA interrupts the oxidative phosphorylation energy metabolism and intestinal Cytochrome-P450 systems. It also disturbs multicellular signaling pathways involved in cell survival and helps in tumor angiogenesis. Moreover, IDA is also responsible for the functional deterioration of innate and adaptive immune systems that lead to immunological dysfunctions against invading pathogens. Genomic instability and immunological dysfunctions are the hallmarks of cancer development. In this review, we will review the evidence linking IDA to increased cancer risk.

Safety and benefits of antenatal oral iron supplementation in low-income countries: a review

The World Health Organization recommends universal iron supplementation of 30-60 mg/day in pregnancy but coverage is low in most countries. Its efficacy is uncertain, however, and there has been a vigorous debate in the last decade about its safety, particularly in areas with a high burden of malaria and other infectious diseases. We reviewed the evidence on the safety and efficacy of antenatal iron supplementation in low-income countries. We found no evidence that daily supplementation at a dose of 60 mg leads to increased maternal Plasmodium infection risk. On the other hand, recent meta-analyses found that antenatal iron supplementation provides benefits for maternal health (severe anaemia at postpartum, blood transfusion). For neonates, there was a reduced prematurity risk, and only a small or no effect on birth weight. A recent trial showed, however, that benefits of antenatal iron supplementation on maternal and neonatal health vary by maternal iron status, with substantial benefits in iron-deficient women. The benefits of universal iron supplementation are likely to vary with the prevalence of iron deficiency. As a consequence, the balance between benefits and risks is probably more favourable in low-income countries than in high-income countries despite the higher exposure to infectious pathogens.

Effect of intra-cellular trafficking on flow cytometric measurement of neutrophil's oxidative status in iron deficient pregnant females

BACKGROUND

Iron deficiency and iron deficiency anemia are prevalent among pregnant women particularly in developing countries. This study aimed to evaluate the iron status among Egyptian pregnant women and its impact on their neutrophil's count and antimicrobial functions.

METHOD

Ninety pregnant females underwent complete blood count, iron profile, flow cytometric studies for neutrophil myeloperoxidase expression & oxidative burst using dihydrorhodamine 123 (DHR) after phorbol-12-myristate-13-acetate (PMA) stimulation as well as neutrophil phagocytic and lytic indices.

RESULTS

According to percent saturation 54/90 women (60%) were iron deficient (<15% saturation) (cases) and 36/90 (40%) were iron sufficient (controls). A higher proportion of iron deficient pregnant women were in their third trimester compared to controls. No significant difference was found between the iron deficient & sufficient groups as regards anemia despite a positive correlation between haemoglobin level and percent saturation (P=.02). Both the phagocytic and lytic indices were significantly lower among the cases compared to controls (P=.014 & .002 respectively). Cases and controls were comparable as regards flow cytometric studies of neutrophils' myeloperoxidase and oxidative burst (P>.05). No significant correlation was found between any of the iron profile parameters and the oxidative burst by flow cytometry.

CONCLUSION

Functional microphage assay (phagocytic and lytic indices) may be more relevant and cost effective than flow cytometry assays of myeloperoxidase and oxidative burst in reflecting either iron status or cellular immunity in pregnancy.

Deferral for low hemoglobin is not associated with increased risk of infection in Danish blood donors

BACKGROUND

Low hemoglobin (Hb) is associated with poor general health and adverse outcomes in a wide range of diseases. However, a link between Hb levels and the risk of infection among healthy individuals has yet to be investigated.

STUDY DESIGN AND METHODS

Using data from the Scandinavian Donations and Transfusions database, 497,390 donors were followed after 5,458,499 donations in health registers. With 1,339,362 person-years of follow-up, Andersen-Gill Cox regression was used to study the association of Hb levels below deferral thresholds, very low Hb levels (in the lowest 0.1 percentile), and declining Hb levels with the risk of infection as measured by hospital or outpatient contact for infection and filling of prescription for antimicrobials, respectively, within 3 months of donation. Analyses were stratified by sex, menopausal status, and frequency of donation.

RESULTS

Hb levels below deferral thresholds were not associated with a risk of hospital contact for infection among premenopausal women (hazard ratio [HR], 1.04; 95% confidence interval [CI], 0.95-1.14), postmenopausal women (HR, 0.77; 95% CI, 0.54-1.11), or men (HR, 0.97; 95% CI, 0.81-1.16), nor was there any association with hospital contact for very low Hb levels or patterns of declining Hb levels. However, subthreshold Hb levels were associated with a reduced risk of antimicrobial prescriptions among premenopausal women (HR, 0.92; 95% CI, 0.91-0.93), postmenopausal women (HR, 0.93; 95% CI, 0.89-0.97), and men (HR, 0.91; 95% CI, 0.88-0.94).

CONCLUSIONS

Neither Hb levels below deferral thresholds nor very low or declining Hb levels were associated with an increased risk of infection. This is reassuring, because blood donation can lead to lower Hb levels.

Biocompatibility and toxicology effects of graphene oxide in cancer, normal, and primary immune cells

Graphene oxide (GO) has received enormous attention regarding its possible applications in medical areas including cancer treatment. Nevertheless, graphene biocompatibility and its interactions with cancer, normal and immune system cells still remain a major issue. In the current study, we focused on the immunological impact of GO in the oxidative burst by GO produced in fresh isolated primary human neutrophils, the most abundant leukocyte of immune system. We also studied the GO cytotoxicity, cell uptake, and genotoxicity in fresh isolated primary human monocyte, neutrophil, human carcinoma cervical (HeLa) and L929 cells. GO biocompatibility was also analyzed in human red blood cell (hemocompatibility) and in primary human T lymphocytes (T cell). We observed that GO can interact with HeLa in vitro and immune system cells, but in major extension with cancer cells. The latter opened the way for further studies on the effects of GO on immune system pathways and treatments for human cancer at lower concentrations. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 728-736, 2017.

Leukocyte production of IFN-γ and TNF-α in 8- to 12-y-old children with low serum iron levels

OBJECTIVE

Iron deficiency is likely the most common nutritional deficiency worldwide; low iron concentrations have been related to alterations in immune system functions; therefore, the aim of this study was to determine the effect of low serum iron (LSI) concentrations on the production of proinflammatory cytokines by peripheral blood leukocytes in 8- to 12-y-old children from a local community.

METHODS

We obtained 120 blood samples and determined full blood counts and serum iron concentrations. An LSI and a control group, paired by age and sex were established using serum iron <60 μg/dL as the cutoff point. Ferritin and C-reactive protein concentrations were quantified. Serum interferon (IFN)-γ and tumor necrosis factor (TNF)-α concentrations were measured in these groups by enzyme-linked immunosorbent assay. A second blood sample was taken from children in both groups to isolate peripheral blood mononuclear cells (PBMCs) and measure IFN-γ and TNF-α production by unstimulated and lipopolysaccharide/phorbol myristate acetate/ionomycin-stimulated leukocytes in vitro.

RESULTS

Of the participants in the present study, 17.5% (21 children) presented LSI, as well as decreased ferritin concentrations. Differential counts from total blood samples showed a significant increase in leukocyte numbers in the LSI group, along with increased neutrophil frequencies and numbers but decreased lymphocyte frequencies. Decreased serum IFN-γ concentrations and decreased in vitro production of IFN-γ by PBMCs were found in the LSI group.

CONCLUSIONS

The results of the present study suggest that low iron levels alter leukocyte subpopulations in circulation and have a detrimental effect on leukocyte production of proinflammatory cytokines after an antigenic challenge.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Poly(vinyl alcohol)-coated silver nanoparticles: activation of neutrophils and nanotoxicology effects in human hepatocarcinoma and mononuclear cells

Silver nanoparticles (AgNps) have been described as important for their excellent biocompatibility, biomedical applications. Nevertheless, AgNps can interact with the immune system which is essential to analyze human exposure to assess their potential risk to health and environment. In general, the primary site for accumulation of nanoparticles has been demonstrated to be the liver. Furthermore, the direct activation of neutrophils or oxidative burst by a given nanoparticle is poorly documented. In this paper, we investigated the cell uptake, apoptosis, necrosis, DNA damage in human hepatocarcinoma cells (HepG2), primary normal human peripheral blood mononuclear cells (PBMC) and the direct activation of primary isolated neutrophils through the oxidative burst on exposure to AgNps coated with Polyvinyl-alcohol (PVA). All cell types were incubated in the presence of 1.0 and 50.0 μM of AgNps-PVA for 24h. A significant cyto- and genotoxic-response and the activation of human neutrophils were induced by AgNps-PVA (p<0.05). Our results revealed that AgNps can interact with the normal isolated neutrophils, PBMC and HepG2 cells in vitro, which opens the way for further studies on the toxicological effects of AgNps in the human immune system response and cancer cells.

Immunological abnormalities associated with hereditary haemorrhagic telangiectasia

OBJECTIVE

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder related to mutations in one of the coreceptors to the transforming growth factor-β superfamily (ALK1 or endoglin). Besides the obvious vascular symptoms (epistaxis and arteriovenous malformations), patients have an unexplained high risk of severe bacterial infections. The aim of the study was to assess the main immunological functions of patients with HHT using the standard biological tests for primary immunodeficiencies.

DESIGN, SETTING AND SUBJECTS

A prospective single-centre study of 42 consecutive adult patients with an established diagnosis of HHT was conducted at the National French HHT Reference Center (Lyon). Lymphocyte subpopulations and proliferation capacity, immunoglobulin levels and neutrophil and monocyte phagocytosis, oxidative burst and chemotaxis were assessed.

RESULTS

Innate immunity was not altered in patients with HHT. With regard to adaptive immunity, significant changes were seen in immunological parameters: primarily, a lymphopenia in patients with HHT compared with healthy control subjects affecting mean CD4 (642 cells μL(-1) vs. 832 cells μL(-1) , P < 0.001), CD8 (295 cells μL(-1) vs. 501 cells μL(-1) , P < 0.0001) and natural killer (NK) cells (169 cells μL(-1) vs. 221 cells μL(-1) , P < 0.01), associated with increased levels of immunoglobulins G and A. This lymphopenia mainly concerned naïve T cells. Proliferation capacities of lymphocytes were normal. Lymphopenic patients had a higher frequency of iron supplementation but no increase in infection rate. Lower levels of immunoglobulin M and a higher rate of pulmonary arteriovenous malformations were found amongst patients with a history of severe infection.

CONCLUSIONS

Patients with HHT exhibit immunological abnormalities including T CD4, T CD8 and NK cell lymphopenia and increased levels of immunoglobulins G and A. The observed low level of immunoglobulin M requires further investigation to determine whether it is a specific risk factor for infection in HHT.

Neurotoxic factors released by stimulated human monocytes and THP-1 cells

Activated monocytes/macrophages are known to release toxic materials. Identification of these materials is important for developing more effective treatments for inflammatory disorders where self attack occurs. We stimulated human monocytes and THP-1 cells with LPS/IFNγ and measured the toxic effects of their conditioned media against differentiated human NT-2 cells. Their cytotoxicity, as measured by LDH release, was reduced by half when their conditioned media was passed through a 3kDa cutoff filter, indicating an equal division between high and low molecular weight materials. When the high molecular weight components tumor necrosis factor-α (TNFα), interleukin-1β (IL-1β), and IL-6 were removed from the conditioned medium by specific antibodies, the toxicity was reduced by 37-38%. When prostaglandin production was blocked by treatment with the COX inhibitors acetylsalicylic acid and ibuprofen, toxicity was reduced by 15-16%. When oxygen free radical production was blocked by the NADPH inhibitor diphenylene iodonium (DPI) the toxicity was reduced by 17-18%. Treatment with the nitric oxide scavenger carboxy-phenyl-tetramethylimidazolineoxyl-oxide, or the NOS inhibitor N(G)-monomethylene-l-arginine, attenuated the toxicity by about 20%. Removal of released glutamate by glutamate decarboxylase also attenuated the toxicity by 12-13%. In combination, these treatments reduced the toxicity by approximately 50% accounting for the low molecular weight component toxicity. About 10% of the overall toxicity, which was associated with the high molecular weight component, was not identified. Optimal antiinflammatory therapy may require combined suppression of these identified toxin-generating pathways as well as relatively minor pathways yet to be identified.