The role of iron in the pathogenesis of atherosclerosis

Decoding ferroptosis: Revealing the hidden assassin behind cardiovascular diseases

The discovery of regulatory cell death processes has driven innovation in cardiovascular disease (CVD) therapeutic strategies. Over the past decade, ferroptosis, an iron-dependent form of regulated cell death driven by excessive lipid peroxidation, has been shown to drive the development of multiple CVDs. This review provides insights into the evolution of the concept of ferroptosis, the similarities and differences with traditional modes of programmed cell death (e.g., apoptosis, autophagy, and necrosis), as well as the core regulatory mechanisms of ferroptosis (including cystine/glutamate transporter blockade, imbalance of iron metabolism, and lipid peroxidation). In addition, it provides not only a detailed review of the role of ferroptosis and its therapeutic potential in widely studied CVDs such as coronary atherosclerotic heart disease, myocardial infarction, myocardial ischemia/reperfusion injury, heart failure, cardiomyopathy, and aortic aneurysm but also an overview of the phenomenon and therapeutic perspectives of ferroptosis in lesser-addressed CVDs such as cardiac valvulopathy, pulmonary hypertension, and sickle cell disease. This article aims to integrate this knowledge to provide a comprehensive view of ferroptosis in a wide range of CVDs and to drive innovation and progress in therapeutic strategies in this field.

Ferroptosis in cardiovascular disease

In the 21st century, cardiovascular disease (CVD) has become one of the leading causes of death worldwide. The prevention and treatment of CVD remain pressing scientific issues. Several recent studies have suggested that ferroptosis may play a key role in CVD. Most studies conducted thus far on ferroptosis and CVD have supported the link. Ferroptosis mediated by different signaling and metabolic pathways can lead to ischemic heart disease, myocarditis, heart failure, ischemia-reperfusion injury, and cardiomyopathy. Still, the specific mechanism of ferroptosis in CVD, the particular organ areas affected, and the stage of disease involved need to be further studied. Therefore, understanding the mechanisms regulating ferroptosis in CVD may improve disease management. Throughout this review, we summarized the mechanism of ferroptosis and its effect on the pathogenesis of CVD. We also predicted and discussed future research directions, aiming to provide new ideas and strategies for preventing and treating CVD.

Iron and atherosclerosis: Lessons learned from rabbits relevant to human disease

The role of iron in promoting atherosclerosis, and hence the cardiovascular, neurodegenerative and other diseases that result from atherosclerosis, has been fiercely controversial. Many studies have been carried out on various rodent models of atherosclerosis, especially on apoE-knockout (apoE-/-) mice, which develop atherosclerosis more readily than normal mice. These apoE-/- mouse studies generally support a role for iron in atherosclerosis development, although there are conflicting results. The purpose of the current article is to describe studies on another animal model that is not genetically manipulated; New Zealand White (NZW) rabbits fed a high-cholesterol diet. This may be a better model than the apoE-/- mice for human atherosclerosis, although it has been given much less attention. Studies on NZW rabbits support the view that iron promotes atherosclerosis, although some uncertainties remain, which need to be resolved by further experimentation.

Cardiovascular Manifestations of Hemochromatosis: A Review of Pathophysiology, Mechanisms, and Treatment Options

Hemochromatosis is a genetic disorder characterized by excessive absorption and accumulation of iron in the body. It is one of the most common inherited disorders. The excess iron deposition can cause damage to various organs, including the liver, heart, pancreas, and joints. If left untreated, hemochromatosis can lead to serious complications such as cirrhosis, diabetes, heart failure, and increased risk of certain cancers. Iron overload in hemochromatosis significantly affects the cardiovascular system, leading to morbidity and mortality. This article reviews the current literature describing the pathogenesis and various cardiovascular manifestations of hemochromatosis, including dilated cardiomyopathy, conduction abnormalities, heart failure, cardiac fibrosis, myocardial infarction, and valvular heart disease. This article aims to provide a detailed understanding of the cardiovascular manifestations associated with hemochromatosis and their underlying mechanisms through a review of current literature in publicly available databases.

The effect of circulating iron on barrier integrity of primary human endothelial cells

Iron is hypothesized to be one of the contributors to cardiovascular disease and its levels in the circulation may correlate with cardiovascular risk. The aim of this study is to investigate the mechanisms that underlie the effects of iron on the barrier function of primary human endothelium. We used Human Umbilical Vein Endothelial Cells (HUVEC) to investigate the effects of Fe3+ using electric cell-substrate impedance sensing, microscopy, western blot and immunofluorescence microscopy. Exposure to Fe3+ caused EC elongation and upregulation of stress-induced proteins. Analysis of barrier function showed a dose-dependent drop in endothelial integrity, which was accompanied by Reactive Oxygen Species (ROS) production and could partly be prevented by ROS scavengers. Inhibition of contractility by the ROCK inhibitor Y27632, showed even more effective rescue of barrier integrity. Using western blot, we detected an increase in expression of the small GTPase RhoB, an inducer of EC contraction, and a small decrease in VE-cadherin, suggestive for an iron-induced stress response. Co-stimulation by TNFα and iron, used to investigate the role of low-grade inflammation, revealed an additive, negative effect on barrier integrity, concomitant with an upregulation of pro-inflammatory markers ICAM-1 and RhoB. Iron induces a response in HUVEC that leads to endothelial activation and a pro-inflammatory state measured by loss of barrier integrity which can be reversed by ROS scavengers, combined with inhibition of contractility. These data suggest that ROS-mediated damage of the vascular endothelium could contribute to the increased cardiovascular risk which is associated with elevated levels of circulating iron.

The suppression of hyperlipid diet-induced ferroptosis of vascular smooth muscle cells protests against atherosclerosis independent of p53/SCL7A11/GPX4 axis

Ferroptosis as a novel programmed cell death that involves metabolic dysfunction due to iron-dependent excessive lipid peroxidation has been implicated in atherosclerosis (AS) development characterized by disrupted lipid metabolism, but the atherogenic role of ferroptosis in vascular smooth muscle cells (VSMCs), which are principal components of atherosclerotic plaque fibrous cap, remains unclear. The aim of this study was to determine the effects of ferroptosis on AS induced by lipid overload, and the effects of that on VSMCs ferroptosis. We found intraperitoneal injection of Fer-1, a ferroptosis inhibitor, ameliorated obviously high-fat diet-induced high plasma levels of triglycerides, total cholesterol, low-density lipoprotein, glucose and atherosclerotic lesions in ApoE-/- mice. Moreover, in vivo and in vitro, Fer-1 reduced the iron accumulation of atherosclerotic lesions through affecting the expression of TFR1, FTH, and FTL in VSMCs. Interestingly, Fer-1 did augment nuclear factor E2-related factor 2/ferroptosis suppressor protein 1 to enhance endogenous resistance to lipid peroxidation, but not classic p53/SCL7A11/GPX4. Those observations indicated inhibition of VSMCs ferroptosis can improve AS lesions independent of p53/SLC7A11/GPX4, which preliminarily revealed the potential mechanism of ferroptosis in aortic VSMCs on AS and provided new therapeutic strategies and targets for AS.

Iron metabolism and atherosclerosis

Despite several decades of study, whether iron is involved in the development of atherosclerosis remains a controversial and unresolved issue. Here, we focus on the up-to-date advances in studies on role of iron in atherosclerosis and discuss possible reasons why patients with hereditary hemochromatosis (HH) do not show any increased incidence of atherosclerosis. In addition, we analyze conflicting results concerning the role of iron in atherogenesis from several epidemiological and animal studies. We argue that atherosclerosis is not observed in HH because iron homeostasis in the arterial wall, the actual location of atherosclerosis, is not significantly affected, and support a causal link between iron in the arterial wall and atherosclerosis.

Single and Combined Associations of Plasma and Urine Essential Trace Elements (Zn, Cu, Se, and Mn) with Cardiovascular Risk Factors in a Mediterranean Population

Trace elements are micronutrients that are required in very small quantities through diet but are crucial for the prevention of acute and chronic diseases. Despite the fact that initial studies demonstrated inverse associations between some of the most important essential trace elements (Zn, Cu, Se, and Mn) and cardiovascular disease, several recent studies have reported a direct association with cardiovascular risk factors due to the fact that these elements can act as both antioxidants and pro-oxidants, depending on several factors. This study aims to investigate the association between plasma and urine concentrations of trace elements and cardiovascular risk factors in a general population from the Mediterranean region, including 484 men and women aged 18−80 years and considering trace elements individually and as joint exposure. Zn, Cu, Se, and Mn were determined in plasma and urine using an inductively coupled plasma mass spectrometer (ICP-MS). Single and combined analysis of trace elements with plasma lipid, blood pressure, diabetes, and anthropometric variables was undertaken. Principal component analysis, quantile-based g-computation, and calculation of trace element risk scores (TERS) were used for the combined analyses. Models were adjusted for covariates. In single trace element models, we found statistically significant associations between plasma Se and increased total cholesterol and systolic blood pressure; plasma Cu and increased triglycerides and body mass index; and urine Zn and increased glucose. Moreover, in the joint exposure analysis using quantile g-computation and TERS, the combined plasma levels of Zn, Cu, Se (directly), and Mn (inversely) were strongly associated with hypercholesterolemia (OR: 2.03; 95%CI: 1.37−2.99; p < 0.001 per quartile increase in the g-computation approach). The analysis of urine mixtures revealed a significant relationship with both fasting glucose and diabetes (OR: 1.91; 95%CI: 1.01−3.04; p = 0.046). In conclusion, in this Mediterranean population, the combined effect of higher plasma trace element levels (primarily Se, Cu, and Zn) was directly associated with elevated plasma lipids, whereas the mixture effect in urine was primarily associated with plasma glucose. Both parameters are relevant cardiovascular risk factors, and increased trace element exposures should be considered with caution.

Oncostatin M: Risks and Benefits of a Novel Therapeutic Target for Atherosclerosis

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death worldwide. It is predicted that approximately 23.6 million people will die from CVDs annually by 2030. Therefore, there is a great need for an effective therapeutic approach to combat this disease. The European Cardiovascular Target Discovery (CarTarDis) consortium identified Oncostatin M (OSM) as a potential therapeutic target for atherosclerosis. The benefits of modulating OSM - an interleukin (IL)-6 family cytokine - have since been studied for multiple indications. However, as decades of high attrition rates have stressed, the success of a drug target is determined by the fine balance between benefits and the risk of adverse events. Safety issues should therefore not be overlooked.

OBJECTIVE

In this review, a risk/benefit analysis is performed on OSM inhibition in the context of atherosclerosis treatment. First, OSM signaling characteristics and its role in atherosclerosis are described. Next, an overview of in vitro, in vivo, and clinical findings relating to both the benefits and risks of modulating OSM in major organ systems is provided. Based on OSM's biological function and expression profile as well as drug intervention studies, safety concerns of inhibiting this target have been identified, assessed, and ranked for the target population.

CONCLUSION

While OSM may be of therapeutic value in atherosclerosis, drug development should also focus on de-risking the herein identified major safety concerns: tissue remodeling, angiogenesis, bleeding, anemia, and NMDA- and glutamate-induced neurotoxicity. Close monitoring and/or exclusion of patients with various comorbidities may be required for optimal therapeutic benefit.

Role of Iron-Related Oxidative Stress and Mitochondrial Dysfunction in Cardiovascular Diseases

Iron is indispensable in numerous biologic processes, but abnormal iron regulation and accumulation is related to pathological processes in cardiovascular diseases. However, the underlying mechanisms still need to be further explored. Iron plays a key role in metal-catalyzed oxidative reactions that generate reactive oxygen species (ROS), which can cause oxidative stress. As the center for oxygen and iron utilization, mitochondria are vulnerable to damage from iron-induced oxidative stress and participate in processes involved in iron-related damage in cardiovascular disease, although the mechanism remains unclear. In this review, the pathological roles of iron-related oxidative stress in cardiovascular diseases are summarized, and the potential effects and mechanisms of mitochondrial iron homeostasis and dysfunction in these diseases are especially highlighted.

The Role of Iron in Atherosclerosis in Apolipoprotein E Deficient Mice

The role of iron in atherosclerosis is still a controversial and unsolved issue. Here, we investigated serum iron, expression of iron regulatory, transport and storage proteins, pro-inflammatory chemokines and cytokines in ApoE–/– mice. We demonstrated that ApoE–/– induced atherosclerosis and an increase in iron contents, expression of transferrin receptor 1 (TfR1), iron regulatory proteins (IRPs), heme oxygenase 1 (HO1), cellular adhesion molecules and pro-inflammatory cytokines, production of reactive oxygen species (ROS), and a reduction in expression of superoxide dismutase and glutathione peroxidase enzyme in aortic tissues. All of these changes induced by ApoE deficiency could be significantly abolished by deferoxamine. The data showed that the increased iron in aortic tissues was mainly due to the increased iron uptake via IRP/TfR1 upregulation. These findings plus a brief analysis of the controversial results reported previously showed that ApoE deficiency-induced atherosclerosis is partly mediated by the increased iron in aortic tissues.

Analysis of oxidative stress, inflammation and endothelial function following intravenous iron in chronic kidney disease in the Iron and Heart Trial

Iron deficiency commonly affects patients with chronic kidney disease and has an important burden in disease trajectory and quality of life; nonetheless current guidelines do not advocate treatment of iron-deficiency without anemia in this patient group. Concerns exist regarding the potential effects of intravenous iron on oxidative stress, inflammation, and endothelial function. As part of a multicenter double-blinded randomized controlled clinical trial, we examined the effects of a single dose of intravenous iron vs. placebo on biomarkers of oxidative stress, inflammation and endothelial function in non-anemic iron deficient patients (serum ferritin < 100 μg/L and/or transferrin saturation < 20%) with chronic kidney disease (stage 3b-5). Fifty-four individuals were randomized to receive ferric derisomaltose (n = 26) or placebo (n = 28). Ferric derisomaltose was associated with a non-significant decrease in mean F2-isoprostane and no effect on thiobarbituric acid reactive substances when compared to placebo throughout follow up. No effect on inflammatory markers was observed. A modest but statistically significant rise in E-selectin was noted in the intravenous iron group at 1 month and 3 month follow-up (p = 0.030 and p = 0.002 respectively). These results suggest ferric derisomaltose administration in non-dialysis dependent chronic kidney disease patients who are iron deficient does not induce prolonged oxidative stress or inflammation. Larger trials are required to quantify the benefit of intravenous iron administration in this patient group.

Body iron stores had no impact on coronary heart disease outcomes: a middle-aged male cohort from the general population with 21-year follow-up

Background

Body iron stores (BISs) have been proposed to be related to the development of cardiovascular diseases. However, results from epidemiological studies are conflicting. Knowledge on the long-term impact of BIS on cardiovascular outcomes in the general population is lacking.

Purpose

The aim of this study was to explore the relationship between BIS and coronary heart disease (CHD) including death due to CHD.

Methods

This investigation is part of ‘The Study of Men Born in 1943’, a longitudinal prospective study of men living in the city of Gothenburg, Sweden. This random population sample was examined in 1993 (all at 50 years of age at baseline). A medical examination was performed, and questionnaires were used to evaluate lifestyle factors. Biomarkers for iron stores (serum ferritin and serum transferrin receptor) was analysed from frozen blood samples in 2014. All hospital admissions were registered through national registers during the entire follow-up from 1993 to 2014. HRs were estimated by Cox proportional-hazard regression analyses.

Results

During the 21 years follow-up period, 120 participants (15.2%) developed CHD and 16 patients (2%) died due to CHD. The all-cause mortality was 15.2% (n=120) including 40 cardiovascular deaths (5.1%). In a multivariable Cox regression analysis, the daily smoking, hypertension and the increased resting heart rate was independent predictors of CHD, while no significant association was found between BIS and risk of CHD.

Conclusions

In a cohort of middle-aged men from the general population with well validated and prospectively collected data, we did not find any association between serum ferritin or serum transferrin receptor as markers of BIS and CHD events after 21 years of follow-up.

Trail registration number

NCT03138122.

NOD1 splenic activation confers ferroptosis protection and reduces macrophage recruitment under pro-atherogenic conditions

The bioavailability and regulation of iron is essential for central biological functions in mammals. The role of this element in ferroptosis and the dysregulation of its metabolism contribute to diseases, ranging from anemia to infections, alterations in the immune system, inflammation and atherosclerosis. In this sense, monocytes and macrophages modulate iron metabolism and splenic function, while at the same time they can worsen the atherosclerotic process in pathological conditions. Since the nucleotide-binding oligomerization domain 1 (NOD1) has been linked to numerous disorders, including inflammatory and cardiovascular diseases, we investigated its role in iron homeostasis. The iron content was measured in various tissues of Apoe^-/- and Apoe^-/-Nod1^-/- mice fed a high-fat diet (HFD) for 4 weeks, under normal or reduced splenic function after ligation of the splenic artery. In the absence of NOD1 the iron levels decreased in spleen, heart and liver regardless the splenic function. This iron decrease was accompanied by an increase in the recruitment of F4/80⁺-macrophages in the spleen through a CXCR2-dependent signaling, as deduced by the reduced recruitment after administration of a CXCR2 inhibitor. CXCR2 mediates monocyte/macrophage chemotaxis to areas of inflammation and accumulation of leukocytes in the atherosclerotic plaque. Moreover, in the absence of NOD1, inhibition of CXCR2 enhanced atheroma progression. NOD1 activation increased the levels of GPX4 and other iron and ferroptosis regulatory proteins in macrophages. Our findings highlight the preeminent role of NOD1 in iron homeostasis and ferroptosis. These results suggest promising avenues of investigation for the diagnosis and treatment of iron-related diseases directed by NOD1.

Alcohol - The myth of cardiovascular protection

BACKGROUND & AIMS

To investigate potential biases that exist in available epidemiological evidence resulting in negative associations or underestimation of cardiovascular (CV) risk associated with alcohol consumption.

METHODS

UK Biobank involved baseline data collection from 22 assessment centres across the United Kingdom. The cohort consisted of 333 259 alcohol consumers and 21 710 never drinkers. Participants were followed up for a median 6.9 years capturing incident fatal and non-fatal CV events, ischemic heart disease and cerebrovascular disease. Alcohol intake was reported as grams/week.

RESULTS

Using never drinkers as reference, alcohol from all drink types combined (hazard ratios ranging between 0.61 and 0.74), beer/cider (0.70-0.80) and spirits combined, and all wines combined (0.66-0.77) associated with a reduced risk for all outcome measures (all CV events, ischaemic heart disease, cerebrovascular disease). In continuous analysis, alcohol captured from all drink types combined (hazard ratio, 1.08, 95% confidence interval, 1.01-1.14), and beer/cider and spirits combined (1.24, 1.17-1.31) associated with an increased risk for overall CV events, however hazard ratios were stronger for beer/cider and spirits (P < 0.0001). Wine associated with a reduced risk for overall CV events (0.92, 0.86-0.98) and ischemic heart disease (0.75, 0.67-0.84). This negative relationship with overall CV events was lost after excluding ischemic heart disease events (1.00, 0.93-1.08), while the positive association of alcohol captured from beer/cider and spirits remained significant (1.30, 1.22-1.40). This positive association with overall CV events was present even when consuming less than 14 units per week.

CONCLUSIONS

Avoiding potential biases prevents underestimation of cardiovascular risk and indicates that consuming up to 14 units per week also associated with increased CV risk in the general population.

Effect of iron overload on endothelial cell calcification and its mechanism

Background

Vascular calcification is related to many diseases. Iron has a certain relationship with endothelial cells and vascular calcification. The purpose of this study was to assess the effect of iron overload on endothelial cell calcification and related mechanisms through cell experiments.

Methods

Human umbilical vein endothelial cells were treated with different concentrations of FeSO₄ (50, 100, 150, and 200 µM), and deferoxamine (DFO) and ferrostatin. Alkaline phosphatase activity, malondialdehyde (MDA) level, reactive oxygen species (ROS) level, and lipid superoxidation after FeSO₄ treatment were assessed. Alizarin red staining was used to observe calcium deposition. Quantitative polymerase chain reaction (qPCR) and western blot were adopted to examine the expression of calcification markers, iron metabolism-related factors, apoptosis pathway-related factors and ferroptosis markers. The TUNEL method was employed to detect cell apoptosis.

Results

FeSO₄ of 100 µM significantly promoted the occurrence of cell ferroptosis, increased the levels of MDA and ROS, and decreased the ratio of glutathione (GSH) or glutathione disulfide (GSSG) and the expression level of glutathione peroxidase (GPX4). The addition of DFO and ferrostatin significantly modified the effects of FeSO₄. Calcium deposition was most obvious in the cells treated with 100 µM FeSO₄. FeSO₄ significantly upregulated Runt-related transcription factor 2 (RUNX2) and Bone morphogenetic protein 2 (BMP2), ferritin heavy chain (FTH) and ferritin light chain (FTL), and downregulated Matrix Gla Protein (MGP) and divalent metal transporter 1 (DMT1). The results also showed that FeSO₄ induced cell apoptosis by TUNEL method. The elevated Bcl2-associated death protein (Bad) and Bcl2-associated X protein (Bax) and the reduction in Bcl-2, p-Bad, p-AKT, and t-AKT were found. DFO and ferrostatin significantly reduced the iron-induced calcification and apoptosis of endothelial cells. DFO significantly increased the expression level of Bcl-2, and reduced the expression level of Bad.

Conclusions

Iron overload contributes to the process of endothelial cell calcification by inducing apoptosis and ferroptosis. Iron chelators and ferroptosis inhibitors alleviate endothelial cell apoptosis, ferroptosis, and calcification induced by iron overload.

Research Progress on Relationship Between Iron Overload and Lower Limb Arterial Disease in Type 2 Diabetes Mellitus

Iron is one of the most important trace elements in life activities. It participates in a variety of important physiological processes in the body through oxidation-reduction reaction. A large number of studies show that iron overload (IO) is closely related to the progression of diabetes and its various chronic complications. However, the mechanism of iron overload in the pathogenesis of diabetes and the mechanism of iron overload in atherosclerosis (AS) are still controversial, and the relationship between iron overload and diabetic lower extremity arterial disease (LEAD) remains still unclear. Some recent reviews and original research articles suggest further studies to explain the complex relationship between iron metabolism and atherosclerosis. This article reviews the relationship between iron overload and diabetes and its relationship with LEAD, and discusses its mechanisms from various aspects, such as lipid peroxidation induced by iron overload, so as to provide clinical diagnosis and treatment ideas for diabetic lower extremity arterial disease. It is hoped that early evaluation, diagnosis and treatment of LEAD will be inspired.

Age-Related Progression of Microvascular Dysfunction in Cystic Fibrosis: New Detection Ways and Clinical Outcomes

There are concerns about altered vascular functions that could play an important role in the pathogenesis and influence the severity of chronic disease, however, increased cardiovascular risk in paediatric cystic fibrosis (CF) has not been yet fully understood. Aim was to analyse vascular disease risk and investigate changes over times in CF and controls. We prospectively enrolled 22 CF subjects (a median age of 16.07 years), and 22 healthy demographically matched controls (a median age of 17.28 years) and determined endothelial function. We utilised a combined diagnostic approach by measuring the plethysmographic Reactive Hyperemia Index (RHI) as the post-to preocclusive endothelium-dependent changes of vascular tone, and biomarkers that are known to be related to endothelial dysfunction (ED): asymmetric dimethyl arginine (ADMA), high-sensitive CRP (hsCRP), VCAM-1 and E-selectin. RHI values were significantly lower in CF young adults (p<0.005). HsCRP (p<0.005), E-selectin (p<0.001) and VCAM-1 (p<0.001) were significantly increased in CF patients since childhood. The findings have provided a detailed account of the ongoing process of microvascular dysfunction with gradual progression with the age of CF patients, making them further at risk of advanced vascular disease. Elevations of biomarkers in CF children with not yet demonstrated RHI changes but with significantly reduced RHI in adulthood and lipid profile changes indicate the possible occurrence of ED with CF-related specific risk factors over time and will enable us to provide the best possible support.

Iron in Cardiovascular Disease: Challenges and Potentials

Iron is essential for many biological processes. Inadequate or excess amount of body iron can result in various pathological consequences. The pathological roles of iron in cardiovascular disease (CVD) have been intensively studied for decades. Convincing data demonstrated a detrimental effect of iron deficiency in patients with heart failure and pulmonary arterial hypertension, but it remains unclear for the pathological roles of iron in other cardiovascular diseases. Meanwhile, ferroptosis is an iron-dependent cell death that is distinct from apoptosis, necroptosis, and other types of cell death. Ferroptosis has been reported in several CVDs, namely, cardiomyopathy, atherosclerotic cardiovascular disease, and myocardial ischemia/reperfusion injury. Iron chelation therapy seems to be an available strategy to ameliorate iron overload-related disorders. It is still a challenge to accurately clarify the pathological roles of iron in CVD and search for effective medical intervention. In this review, we aim to summarize the pathological roles of iron in CVD, and especially highlight the potential mechanism of ferroptosis in these diseases.

Interchangeable utilization of metals: New perspectives on the impacts of metal ions employed in ancient and extant biomolecules

Metal ions provide considerable functionality across biological systems, and their utilization within biomolecules has adapted through changes in the chemical environment to maintain the activity they facilitate. While ancient earth's atmosphere was rich in iron and manganese and low in oxygen, periods of atmospheric oxygenation significantly altered the availability of certain metal ions, resulting in ion replacement within biomolecules. This adaptation mechanism has given rise to the phenomenon of metal cofactor interchangeability, whereby contemporary proteins and nucleic acids interact with multiple metal ions interchangeably, with different coordinated metals influencing biological activity, stability, and toxic potential. The ability of extant organisms to adapt to fluctuating metal availability remains relevant in a number of crucial biomolecules, including the superoxide dismutases of the antioxidant defense systems and ribonucleotide reductases. These well-studied and ancient enzymes illustrate the potential for metal interchangeability and adaptive utilization. More recently, the ribosome has also been demonstrated to exhibit interchangeable interactions with metal ions with impacts on function, stability, and stress adaptation. Using these and other examples, here we review the biological significance of interchangeable metal ions from a new angle that combines both biochemical and evolutionary viewpoints. The geochemical pressures and chemical properties that underlie biological metal utilization are discussed in the context of their impact on modern disease states and treatments.

Iron metabolism: pathophysiology and pharmacology

Iron is essential in many physiological processes, including DNA metabolism, oxygen transport, and cellular energy generation. Deregulated iron metabolism, which results in iron overload or iron deficiency, is observed in many different diseases. We here summarize recent progress in the pathophysiology and pharmacology of iron-overload diseases, such as hereditary hemochromatosis, as well as iron-deficiency disorders, which are typically associated with anemia. The role of iron in immunity and the connection between iron and cancer are also addressed. We finally summarize and discuss the current (pre-) clinical landscape of pharmacotherapies targeting key players involved in iron metabolism.

Ironing Out the Details: How Iron Orchestrates Macrophage Polarization

Iron fine-tunes innate immune responses, including macrophage inflammation. In this review, we summarize the current understanding about the iron in dictating macrophage polarization. Mechanistically, iron orchestrates macrophage polarization through several aspects, including cellular signaling, cellular metabolism, and epigenetic regulation. Therefore, iron modulates the development and progression of multiple macrophage-associated diseases, such as cancer, atherosclerosis, and liver diseases. Collectively, this review highlights the crucial role of iron for macrophage polarization, and indicates the potential application of iron supplementation as an adjuvant therapy in different inflammatory disorders relative to the balance of macrophage polarization.

Increased serum ferritin is associated with oxidized low-density lipoprotein in prediabetes patients: A pilot study

Aims

This pilot study aimed to determine if increased serum ferritin (SF) is associated with cardiovascular risk factors in patients with prediabetes.

Methods

Eighteen patients with prediabetes and 36 subjects without prediabetes (control), non-white Hispanic, non-indigenous origin, Mexican mestizo descent were included. Participants had no inflammation, or vascular complications. SF and metabolic markers were evaluated in both groups.

Results

SF and oxidized low-density lipoprotein (oxLDL) were increased in prediabetes subjects. Moreover, in prediabetes and control groups as a whole, natural logarithm (ln)-SF correlated with oxLDL and ln-oxLDL/LDL after adjustment for sex, ln-age, ln-fasting plasma glucose (FPG), ln-body mass index, ln-triglyceride (TG), total cholesterol (TC), and high-density lipoproteins. Finally, ln-SF was an independent contributor to ln-oxLDL/LDL ratio in control and prediabetes subjects (β = 0.2915) after the introduction of potential confounders such as FPG, TC, TG, and hypertension.

Conclusions

The results of this study indicate that hyperferritinemia is associated with oxLDL, considered one of the main cardiovascular risk factors, which allows us to suggest that an increase in SF could contribute to the progression of prediabetes, prior to the appearance of diabetes. Further research is required to establish a causal relationship of iron disruption metabolism in oxLDL generation under prediabetes conditions.

Nobiletin Regulates ROS/ADMA/DDAHII/eNOS/NO Pathway and Alleviates Vascular Endothelium Injury by Iron Overload

Iron overload is harmful to health and associates with intracellular excessive reactive oxygen species (ROS) generation. Nobiletin (Nob) is known to be antioxidant and anti-inflammatory. However, whether Nob can protect endothelial cells against iron overload has not been studied, and the specific mechanism has not yet been elucidated. In this study, we have identified the protective effects of Nob, and its underlying molecular mechanism in human umbilical vein endothelial cells (HUVECs) suffered from iron overload via ROS/ADMA/DDAHII/eNOS/NO pathway. We found that compared with 50 μM iron dextran treatment, co-treatment with 20 μM Nob increased cell viability and decreased lactate dehydrogenase activity. Besides, Nob could upregulate DDAHII expression and activity, promote eNOS phosphorylation to produce more NO, reduce ADMA content, and therefore increase superoxide dismutase, catalase, and glutathione peroxidase activities, and decrease malondialdehyde level and ROS generation. Nob also inhibited mitochondrial permeability transition pore (mPTP) openness and cleaved caspase-3 expression, and decreased apoptosis induced by iron overload. These results were consistent when Nob was replaced by the positive control reagents L-arginine (a competitive substrate of ADMA), cyclosporin A (an mPTP closing agent), or edaravone (a free radical scavenger). The addition of pAD/DDAHII-shRNA adenovirus reversed the above effects of Nob. These data suggested that the protective mechanism of Nob was to inhibit ROS burst, upregulate DDAHII expression and activity, promote eNOS phosphorylation, produce NO, reduce ADMA content, and ultimately alleviate iron overload damage in vascular endothelium.

Nano-sensing and nano-therapy targeting central players in iron homeostasis

Iron plays vital roles in many life activities and it is strictly controlled via elaborate metabolic system. Growing evidence has suggested that the dysfunctional iron homeostasis is implicated to many refractory diseases including cancers and neurodegenerations. Systemic and cellular iron are regulated through different pathways but are meanwhile interconnecting with each other via a few key regulators, whose abnormal expressions are often found to be the root causes of many iron disorders. Nano-sensing techniques have enabled the detection and monitoring of such central players, which provide rich information for the iron homeostasis profile through multiplexing and flexible designs. In addition to general sensing, nanoprobes are capable of target imaging and precise local access, which are particularly beneficial for revealing the conditions of intra-/extracellular environments. Nanomaterials have also been applied in some therapies, targeting the aberrant iron metabolism. Various iron uptake pathways have been utilized for target drug delivery and iron level manipulation, while abnormal iron content is notably useful in tumor killing. With brief introduction to the significance of iron homeostasis, this review includes recent works regarding the nanotechnology that has been applied in iron-related diagnostic and therapeutic applications. This article is categorized under: Diagnostic Tools > Biosensing Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Potential hazards of recent trends in liberal iron use for renal anemia

A randomized controlled trial,the Proactive IV Iron Therapy in Haemodialysis Patients (PIVOTAL), has recently shown that a high-dose (‘proactive’) intravenous iron regimen was superior to a low-dose (‘reactive’) regimen for hemodialysis patient outcomes and overall safety. However, even in the low-dose group, a substantial amount of iron was administered to maintain serum ferritin >200 ng/mL. This type of comparison may have strongly affected the safety results. Iron has two opposite effects on erythropoiesis: it activates erythroid differentiation directly by supplying iron but inhibits it indirectly by stimulating hepcidin and enhancing oxidative stress. Hepcidin plays an essential role not only in iron homeostasis and the anemia of chronic kidney disease, but also in its complications such as atherosclerosis and infection. Its main stimulation by iron—and to a lesser degree by inflammation—should urge clinicians to avoid prescribing excessive amounts of iron. Furthermore, as serum ferritin is closely correlated with serum hepcidin and iron storage, it would seem preferable to rely mainly on serum ferritin to adjust iron administration, defining an upper limit for risk reduction. Based on our estimations, the optimal range of serum ferritin is ∼50–150 ng/mL, which is precisely within the boundaries of iron management in Japan. Considering the contrasting ranges of target ferritin levels between end-stage renal disease patients in Japan and the rest of the world, the optimal range proposed by us will probably be considered as unacceptable by nephrologists abroad. Only well-balanced, randomized controlled trials with both erythropoiesis-stimulating agents and iron will allow us to settle this controversy.

Iron overload is related to elevated blood glucose levels in obese children and aggravates high glucose-induced endothelial cell dysfunction in vitro

INTRODUCTION

This study was performed to investigate the role of iron overload in the early stage of hyperglycemia-induced vascular functional impairment.

RESEARCH DESIGN AND METHODS

A total of 196 obese children were enrolled, and data regarding ferritin levels, blood glucose levels, intima-media thickness of carotid arteries, liver function and fibrosis index, hemoglobin, blood pressure, blood lipids, and inflammation indicators were collected. Ferritin levels were compared with a control group, which consisted of 148 healthy non-obese children who were age-matched and gender-matched. Endothelial cells were cultured in high glucose medium and supplemented with ferric citrate with or without iron remover (deferoxamine), a reducing agent (N-acetyl-cysteine), or a nuclear factor-κB (NF-κB) inhibitor (BAY 11-7082). Apoptosis, oxidative stress, nitric oxide levels, and endothelin content were evaluated. DNA microarray analysis was performed to analyze the expression of genes in the NF-κB signaling pathway.

RESULTS

Obese children have significantly higher ferritin levels compared with the control group. Ferritin level was positively correlated with hemoglobin and was related to metabolic disorders, including impaired glucose tolerance, higher blood pressure, dyslipidemia, and impaired hepatic function. Endothelial cells treated with ferric citrate showed a significantly higher rate of apoptosis, higher levels of oxidative stress, and impaired vasomotor function under high glucose conditions. The above effects were rescued by treatment with an iron remover, reducing agent, or NF-κB inhibitor. Further, detection of phosphorylated-p65 distribution in cells confirmed activation of the NF-κB pathway. DNA microarrays and subsequent gene oncology enrichment analyses revealed the main processes activated in cells.

CONCLUSION

Increased ferritin levels are related to impaired glucose tolerance and other metabolic disorders in obese children. At the cellular level, iron overload aggravated the endothelial cell dysfunction caused by high glucose.

Ferritin: An Inflammatory Player Keeping Iron at the Core of Pathogen-Host Interactions

Iron is an essential element for virtually all cell types due to its role in energy metabolism, nucleic acid synthesis and cell proliferation. Nevertheless, if free, iron induces cellular and organ damage through the formation of free radicals. Thus, iron levels must be firmly controlled. During infection, both host and microbe need to access iron and avoid its toxicity. Alterations in serum and cellular iron have been reported as important markers of pathology. In this regard, ferritin, first discovered as an iron storage protein, has emerged as a biomarker not only in iron-related disorders but also in inflammatory diseases, or diseases in which inflammation has a central role such as cancer, neurodegeneration or infection. The basic research on ferritin identification and functions, as well as its role in diseases with an inflammatory component and its potential as a target in host-directed therapies, are the main considerations of this review.

Tetramethylpyrazine alleviates iron overload damage in vascular endothelium via upregulating DDAHII expression

Iron overload causes vascular endothelium damage. It has been thought to relate excessive reactive oxygen species (ROS) generation. Tetramethylpyrazine (TMP), an active ingredient of Ligusticum chuanxiong Hort, protects various cells by inhibiting oxidative stress and cascade reaction of apoptosis. However, whether TMP can increase DDAHII activity and expression against endothelial cell damage induced by iron overload, and the protective mechanism has not been elucidated. In this study, 50 μM iron dextran and 25 μM TMP were used to co-treat HUVECs for 48 h. TMP could increase cell viability and decrease LDH activity, enhance DDAHII expression and activity, p-eNOS/eNOS ratio, NO content, and reduce ADMA level. TMP also showed a strong antioxidant activity with inhibited ROS generation and oxidative stress. Moreover, TMP attenuated mitochondrial membrane potential loss, inhibited mitochondrial permeability transition pore openness, and decreased apoptosis induced by iron overload. While mentioned above, the protective effects of TMP were abolished with the addition of pAD/DDAHII-shRNA. The effects of TMP against iron overload were similar to the positive control groups, L-arginine, a competitive substrate of ADMA, or edaravone, free radical scavenger. These results signify that TMP alleviated iron overload damage in vascular endothelium via ROS/ADMA/ DDAHII/eNOS/NO pathway.

The role of hepcidin and iron homeostasis in atherosclerosis

Atherosclerotic cardiovascular disease is a major burden on global health and a leading cause of death worldwide. The pathophysiology of this chronic disease is complex, involving inflammation, lipoprotein oxidation and accumulation, plaque formation, and calcification. In 1981, Dr. Jerome Sullivan formulated the 'Iron Hypothesis', suggesting that higher levels of stored iron promote cardiovascular diseases, whereas iron deficiency may have an atheroprotective effect. This hypothesis has stimulated research focused on clarifying the role of iron in the development of atherosclerosis. However, preclinical and clinical studies have produced contradictory results and the observation that patients with hemochromatosis do not appear to have an increased risk of atherosclerosis seemed incongruous with Sullivan's initial hypothesis. The 'paradox' of systemic iron overload not being accompanied by an increased risk for atherosclerosis led to a refinement of the iron hypothesis focusing on intracellular macrophage iron. More recent in vitro and animal studies have elucidated the complex signaling pathways regulating iron, with a particular focus on hepcidin, the master regulator of body iron homeostasis. Bone morphogenetic protein (BMP) signaling is the major pathway that is required for induction of hepcidin expression in response to increasing levels of iron. Strong links between iron homeostasis, BMP signaling, inflammation and atherosclerosis have been established in both mechanistic and human studies. This review summarizes the current understanding of the role of iron homeostasis and hepcidin in the development of atherosclerosis and discusses the BMP-hepcidin-ferroportin axis as a novel therapeutic target for the treatment of cardiovascular disease.

Drink types unmask the health risks associated with alcohol intake - Prospective evidence from the general population

BACKGROUND & AIMS

Uncertainty still exists on the impact of low to moderate consumption of different drink types on population health. We therefore investigated the associations of different drink types in the form of beer/cider, champagne/white wine, red wine and spirits with various health outcomes.

METHODS

Over 500,000 participants were recruited to the UK Biobank cohort. Alcohol consumption was self-reported as pints beer/cider, glasses champagne/white wine, glasses of red wine, and measures of spirits per week. We followed health outcomes for a median of 7.02 years and reported all-cause mortality, cardiovascular events, ischemic heart disease, cerebrovascular events, and cancer.

RESULTS

In continuous analysis after excluding non-drinkers, beer/cider and spirits intake associated with an increased risk for all-cause mortality (beer/cider: hazard ratio, 1.56; 95% confidence interval, 1.45-1.68; spirits: 1.47; 1.35-1.60), cardiovascular events (beer/cider: 1.25; 1.17-1.33; spirits: 1.25; 1.16-1.36), ischemic heart disease (beer/cider:1.12; 0.99-1.26 [P = 0.056]; spirits: 1.17; 1.02-1.35), cerebrovascular disease (beer/cider: 1.63; 1.32-2.02; spirits: 1.59; 1.25-2.02) and cancer (beer/cider: 1.14; 1.05-1.24; spirits: 1.14; 1.03-1.26), while both champagne/white wine and red wine associated with a decreased risk for ischemic heart disease only (champagne/white wine: 0.84; 0.72-0.98; red wine: 0.88; 0.77-0.99).

CONCLUSIONS

Our findings do not support the notion that alcohol from any drink type is beneficial to health. Consuming low levels of beer/cider and spirits already associated with an increased risk for all health outcomes, while wine showed opposite protective relationships only with ischemic heart disease.

Quercetin protects the vascular endothelium against iron overload damages via ROS/ADMA/DDAHⅡ/eNOS/NO pathway

The aberrant accumulation of iron causes vascular endothelium damage, which is thought to be associated with excess reactive oxygen species (ROS) generation. Quercetin (Que), as a flavonoid, has a certain ability to scavenge free radicals. Therefore, we aimed to explore the protective mechanism of Que on iron overload induced HUVECs injury focused on ROS/ADMA/DDAHⅡ/eNOS/NO pathway. In this study, HUVECs was treated with 50 μM iron dextran and 20 μM Que for 48 h. We found that Que attenuated the damages induced by iron, as evidenced by decreased ROS generation, increased DDAHⅡexpression and activity, reduced ADMA level, increased NO content and p-eNOS/eNOS ratio, and eventually caused a decrease in apoptosis. After addition of pAD/DDAHⅡ-shRNA, the effects of Que mentioned above were reversed. Meanwhile, iron overload induced mitochondrial oxidative stress, reduced mitochondrial membrane potential and increased mitochondrial permeability transition pores (mPTP) opening, which were also partially alleviated by Que. In addition, L-arginine (L-Arg), a ADMA competition substrate, ciclosporin A (CsA), a mPTP blocking agent, and edaravone (Eda), a free radical scavenger, were used as positive control reagents. The effects of Que were similar to that of L-Arg, CsA and Eda treatment. These results illustrated that Que could attenuate iron overload induced HUVECs mitochondrial dysfunction via ROS/ADMA/DDAHⅡ/eNOS/NO pathway.

Iron Overload Damages the Endothelial Mitochondria via the ROS/ADMA/DDAHII/eNOS/NO Pathway

It has been recognized that iron overload may harm the body's health. Vascular endothelial cells (VECs) are one of the main targets of iron overload injury, and the mechanism involved was thought to be related to the excessive generation of reactive oxygen species (ROS). However, the subcellular and temporal characteristics of ROS generation, potential downstream mechanisms, and target organelles in VECs injured by iron overload have not been expounded yet. In this study, we elucidated the abovementioned issues through both in vivo and in vitro experiments. Mice were fed pellet diets that were supplemented with iron for 4 consecutive months. Results showed that the thoracic aortic strips' endothelium-dependent dilation was significantly impaired and associated with inflammatory changes, noticeable under brown TUNEL-positive staining in microscopy analysis. In addition, the serum content of asymmetric dimethylarginine (ADMA) increased, whereas nitric oxide (NO) levels decreased. Furthermore, the dimethylarginine dimethylaminohydrolase II (DDAHII) expression and activity, as well as the phosphorylation of endothelial nitric oxide synthase (eNOS) in aortic tissue, were inhibited. Human umbilical vein endothelial cells were treated with 50 μM iron dextran for 48 hours, after which the cell viability, NO content, DDAHII expression and activity, and phosphorylation of eNOS decreased and lactate dehydrogenase and caspase-3 activity, ADMA content, and apoptotic cells significantly increased. After the addition of L-arginine (L-Arg) or pAD/DDAHII, the abovementioned changes were reversed. By dynamically detecting the changes of ROS generation in the cytoplasm and mitochondria and interfering with different aspects of signaling pathways, we have confirmed for the first time that excessive ROS originates from the cytoplasm and activates the ROS-induced ROS release (RIRR) mechanism, leading to mitochondrial dysfunction. Together, our data suggested that excessive free iron ions produced excess ROS in the cytoplasm. Thus, excess ROS create one vicious circle by activating the ADMA/eNOS/DDAHII/NO pathway and another vicious circle by activation of the RIRR mechanism, which, when combined, induce a ROS burst, resulting in mitochondrial dysfunction and damaged VECs.

The Effects of Dietary Polyphenols on Circulating Cardiovascular Disease Biomarkers and Iron Status: A Systematic Review

The prevalence of cardiovascular disease (CVD) is rising worldwide, remaining the major cause of death in developed countries. Polyphenols have been shown to have cardioprotective properties; however, their impact on iron bioavailability and potential impact on other aspects of health is unclear. A systematic review was undertaken to evaluate the current status of the relationship between habitual polyphenol consumption, iron status, and circulating biomarkers of CVD. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines, searches were performed across 5 electronic databases (PubMed, Cochrane Library, Scopus, Web of Science, and CINAHL) to identify randomized controlled trials which investigated the effects of polyphenol consumption on inflammatory markers, serum lipid profile, and iron absorption and bioavailability. In total, 1174 records were identified, with only 7 studies meeting the inclusion criteria. The selected studies involved 133 participants and used a variety of foods and supplements, including olive oil and cherries, rich in polyphenols including hydroxytyrosol, quercetin, and resveratrol, as well as catechin enriched drinks. The duration of the studies ranged from between 56 and 145 days, with total polyphenolic content of the food items and supplements ranging from 45 to 1015 mg (per 100 g). Polyphenols did not appear to interfere with iron status, and most studies reported improvements in inflammatory markers and lipid profile. While these results are promising, the limited number of studies and considerable heterogeneity across the interventions support the need for more extensive trials assessing the relationship between polyphenol intake, iron bioavailability, and CVD risk.

Effects of Genetically Determined Iron Status on Risk of Venous Thromboembolism and Carotid Atherosclerotic Disease: A Mendelian Randomization Study

Background Systemic iron status has been implicated in atherosclerosis and thrombosis. The aim of this study was to investigate the effect of genetically determined iron status on carotid intima-media thickness, carotid plaque, and venous thromboembolism using Mendelian randomization. Methods and Results Genetic instrumental variables for iron status were selected from a genome-wide meta-analysis of 48 972 subjects. Genetic association estimates for carotid intima-media thickness and carotid plaque were obtained using data from 71 128 and 48 434 participants, respectively, and estimates for venous thromboembolism were obtained using data from a study incorporating 7507 cases and 52 632 controls. Conventional 2-sample summary data Mendelian randomization was performed for the main analysis. Higher genetically determined iron status was associated with increased risk of venous thromboembolism. Odds ratios per SD increase in biomarker levels were 1.37 (95% CI 1.14-1.66) for serum iron, 1.25 (1.09-1.43) for transferrin saturation, 1.92 (1.28-2.88) for ferritin, and 0.76 (0.63-0.92) for serum transferrin (with higher transferrin levels representing lower iron status). In contrast, higher iron status was associated with lower risk of carotid plaque. Corresponding odds ratios were 0.85 (0.73-0.99) for serum iron and 0.89 (0.80-1.00) for transferrin saturation, with concordant trends for serum transferrin and ferritin that did not reach statistical significance. There was no Mendelian randomization evidence of an effect of iron status on carotid intima-media thickness. Conclusions These findings support previous work to suggest that higher genetically determined iron status is protective against some forms of atherosclerotic disease but increases the risk of thrombosis related to stasis of blood.

Ferritin in Kidney and Vascular Related Diseases: Novel Roles for an Old Player

Iron is at the forefront of a number of pivotal biological processes due to its ability to readily accept and donate electrons. However, this property may also catalyze the generation of free radicals with ensuing cellular and tissue toxicity. Accordingly, throughout evolution numerous pathways and proteins have evolved to minimize the potential hazardous effects of iron cations and yet allow for readily available iron cations in a wide variety of fundamental metabolic processes. One of the extensively studied proteins in the context of systemic and cellular iron metabolisms is ferritin. While clinicians utilize serum ferritin to monitor body iron stores and inflammation, it is important to note that the vast majority of ferritin is located intracellularly. Intracellular ferritin is made of two different subunits (heavy and light chain) and plays an imperative role as a safe iron depot. In the past couple of decades our understanding of ferritin biology has remarkably improved. Additionally, a significant body of evidence has emerged describing the significance of the kidney in iron trafficking and homeostasis. Here, we briefly discuss some of the most important findings that relate to the role of iron and ferritin heavy chain in the context of kidney-related diseases and, in particular, vascular calcification, which is a frequent complication of chronic kidney disease.

The Use of Trace and Essential Elements in Common Clinical Disorders: Roles in Assessment of Health and Oxidative Stress Status

During the early life, the diet of infants is mainly dominated by milk. Milk is a natural food rich in trace elements focus on essential elements. These elements are very necessary for human metabolism and since they cannot be synthesized by the body, the only source available for the humans to obtain them is by ingestion of natural food. This mini-review aims at updating the knowledge on trace elements, outlining their natural food sources, and their possible implications in common clinical disorders in early and adult life. However, it was found that consumption of food with micronutrients and trace elements may release intracellular compounds and offer oxidative protection or exacerbate oxidative damage to metabolically compromised cells.

Mobilization of iron from ferritin: new steps and details

Much evidence indicates that iron stored in ferritin is mobilized through protein degradation in lysosomes, but concerns about this process have lingered, and the mechanistic details of its aspects are lacking. In the studies presented here, ⁵⁹Fe-labeled ferritin was induced by preloading hepatic (HepG2) cells with radiolabeled Fe. Placing these cells in a medium containing desferrioxamine resulted in the loss of ferritin-⁵⁹Fe, but adding high concentrations of reducing agents or modulating the internal GSH concentration failed to alter the rates of ferritin-⁵⁹Fe release. Confocal microscopy showed that Fe deprivation increased the movement of ferritin into lysosomes and hyperaccumulation was observed when lysosomal proteolysis was inhibited. It also resulted in the rapid movement of DMT1 to lysosomes, which was inhibited by bafilomycin. Ferrihydrite crystals isolated from purified rat liver/spleen ferritin were solubilized at pH 5 and 7 by GSH, ascorbate, citrate and lysosomal fluids obtained from livers and J774a.1 macrophages. The inhibition of DMT1/Nramp2 and siRNA knockdown of Nramp1 each reduced the transfer of ⁵⁹Fe from lysosomes to the cytosol; and hepatocyte-specific knockout of DMT1 in mice prevented the release of Fe from the liver responding to EPO treatment, but did not inhibit lysosomal ferritin degradation. We conclude that ferritin-Fe mobilization does not occur through changes in cellular concentrations of reducing/chelating agents but by the coordinated movement of ferritin and DMT1 to lysosomes, where the ferrihydrite crystals exposed by ferritin degradation dissolve in the lysosomal fluid, and the reduced iron is transported back to the cytosol via DMT1 in hepatocytes, and by both DMT1 and Nramp1 in macrophages, prior to release into the blood or storage in ferritin.

The comparison of zinc, copper and iron levels in serum, aorta and left internal mammarian artery tissues in coronary by-pass graft surgery patients

Trace elements are crucial for vital enzymatic reactions in all metabolic processes. Zinc (Zn) acts as a co-factor for many enzymes. Copper (Cu) and iron (Fe) have pro-atherogenic effects resulting in atherosclerosis. Aorta exposing high pulsatile pressure is sensitive for atherosclerosis because of its fast metabolism and poor nutrition by diffusion from vasa vasorum. We aimed to determine the relationship between serum Zn, Cu and Fe levels with aortic and left internal mammary artery (LIMA) tissues in 33 atherosclerotic individuals who inevitably underwent coronary artery by-pass graft (CBAG) surgery that is an end-point treatment for atherosclerosis. Trace elements in serum and tissues were measured using inductively coupled plasma-optical emission spectrophotometer. Pre-operative (Pre-op) serum Fe levels were statistically 46% higher than post-operative (Post-op) values (p = 0.009). Aortic Fe level was 49.8% higher than LIMA Fe (p = 0.0001). Our study points out the tendency of aortic tissue to atherosclerosis via pro- atherogenic effect of Fe. LIMA, being a potential graft for CBAG, is resistant to atherosclerosis with its intimal specialty of graft patency. In conclusion, serum Zn, Cu and Fe levels in atherosclerotic CBAG patients might be monitored to reveal minor alterations pre-operatively and post-operatively for ameliorating the treatment and life quality.

Molecular Fingerprints of Iron Parameters among a Population-Based Sample

Iron deficiency is the most frequent deficiency disease and parameters of iron metabolism appear to be linked to major metabolic and cardiovascular diseases. We screened a large set of small molecules in plasma for associations with iron status among apparently healthy subjects to elucidate subclinical profiles which may provide a link between iron status and onset of diseases. Based on mass spectrometry and nuclear magnetic resonance spectroscopy we determined 613 plasma metabolites and lipoprotein subfractions among 820 apparently healthy individuals. Associations between ferritin, transferrin, haemoglobin and myoglobin and metabolite levels were tested by sex-specific linear regression analyses controlling for common confounders. Far more significant associations in women (82 out of 102) compared to men became obvious. The majority of the metabolites associated with serum ferritin and haemoglobin in women comprising fatty acid species, branched-chain amino acid catabolites and catabolites of heme. The latter was also obvious among men. Positive associations between serum transferrin and VLDL and IDL particle measures seen in women were observed in men with respect to serum ferritin. We observed a sexual-dimorphic fingerprint of surrogates of iron metabolism which may provide a link for the associations between those parameters and major metabolic and cardiovascular disease.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

Iron loading, alcohol and mortality: A prospective study

BACKGROUND & AIMS

The relationship between total body iron and cardiovascular disease remains controversial and information absent in black sub-Saharan Africans in whom alcohol consumption tends to be high. The level of total body iron is tightly regulated, however this regulation is compromised by high alcohol intake causing iron loading. The aim of this study is to investigate total body iron, as represented by serum ferritin, and its interaction with measures of alcohol intake in predicting all-cause and cardiovascular mortality.

METHODS

We followed health outcomes for a median of 9.22 years in 877 randomly selected HIV negative African women (mean age: 50.4 years).

RESULTS

One hundred and five deaths occurred of which 40 were cardiovascular related. Ferritin averaged 84.0 (5th to 95th percentile interval, 7.5-533.3) ng/ml and due to the augmenting effect of inflammation, lowered to 75.3 (6.9-523.2) ng/ml after excluding 271 participants with high-sensitivity C-reactive protein (CRP) levels (above 8 mg/l). CRP increased by quartiles of ferritin in the total group (P trend = 0.002), but this relationship was absent after excluding the 271 participants with high CRP values (P trend = 0.10). Ferritin, gamma-glutamyl transferase and carbohydrate deficient transferrin (all P < 0.0001) were higher in drinkers compared to non-drinkers, but CRP was similar (P = 0.77). In multivariable-adjusted analyses, ferritin predicted both all-cause (hazard ratio, 2.08; 95% confidence interval, 1.62-2.68; P < 0.0001) and cardiovascular (1.94; 1.29-2.92; P = 0.002) mortality. In participants with CRP levels below or equal to 8 mg/l, the significant relationship remained between ferritin and all-cause (2.51; 1.81-3.49; P < 0.0001) and cardiovascular mortality (2.34; 1.45-3.76; P = 0.0005). In fully adjusted models, interactions existed between ferritin and gamma-glutamyl transferase, self-reported alcohol use and carbohydrate deficient transferrin in predicting all-cause (P ≤ 0.012) and cardiovascular mortality (P ≤ 0.003).

CONCLUSIONS

Iron loading in African women predicted all-cause and cardiovascular mortality and the intake of alcohol seems mechanistically implicated.

Excessive Erythrocytosis and Cardiovascular Risk in Andean Highlanders

Corante, Noemí, Cecilia Anza-Ramírez, Rómulo Figueroa-Mujíca, José Luis Macarlupú, Gustavo Vizcardo-Galindo, Grzegorz Bilo, Gianfranco Parati, Jorge L. Gamboa, Fabiola León-Velarde, and Francisco C. Villafuerte. Excessive erythrocytosis and cardiovascular risk in Andean highlanders. High Alt Med Biol. 19:221–231, 2018.—Cardiovascular diseases are the main cause of death worldwide. Life under high-altitude (HA) hypoxic conditions is believed to provide highlanders with a natural protection against cardiovascular and metabolic diseases compared with sea-level inhabitants. However, some HA dwellers become intolerant to chronic hypoxia and develop a progressive incapacitating syndrome known as chronic mountain sickness (CMS), characterized by excessive erythrocytosis (EE; Hb ≥21 g/dL in men, Hb ≥19 g/dL in women). Evidence from HA studies suggests that, in addition to CMS typical signs and symptoms, these highlanders may also suffer from metabolic and cardiovascular disorders. Thus, we hypothesize that this syndrome is also associated to the loss of the cardiometabolic protection observed in healthy highlanders (HH), and therefore to a higher cardiovascular risk (CVR). The aim of the present work was to evaluate the association between EE and CVR calculated using the Framingham General CVR Score and between EE and CVR factors in male highlanders. This cross-sectional study included 342 males from Cerro de Pasco, Peru at 4340 m (HH = 209, CMS = 133). Associations were assessed by multiple logistic regressions adjusted for potential confounders (BMI, pulse oxygen saturation and age). The adjusted models show that the odds of high CVR (>20%) in highlanders with EE was 3.63 times the odds in HH (CI 95%:1.22–10.78; p = 0.020), and that EE is associated to hypertension, elevated fasting serum glucose, insulin resistance, and elevated fasting serum triglycerides. Our results suggest that individuals who suffer from EE are at increased risk of developing cardiovascular events compared with their healthy counterparts.

Iron reduction response and demographic differences between diabetics and non-diabetics with cardiovascular disease entered into a controlled clinical trial

Filings of elemental iron separated magnetically from a homogenate of breakfast cereal implicated in the risk of cardiovascular disease and diabetes.

Effects of long-term exposure to particulate matter and metal components on mortality in the Rome longitudinal study

BACKGROUND

The effect of long-term exposure to metal components in particulate matter on mortality are still controversial.

OBJECTIVES

To study the association between long-term exposure to PM₁₀, PM_2.5, PM_2.5 absorbance, particulate matter components (copper, iron, zinc, sulfur, silicon, potassium, nickel, and vanadium) and non-accidental, cardiovascular (CVD), and ischemic heart disease (IHD) mortality.

METHODS

All 30+ year olds from the Rome Longitudinal Study were followed for vital status from October 2001 until December 2010. We used land use regression models to estimate annual average concentrations at residences and Cox models to estimate the associations between pollutants and cause-specific mortality, adjusting for individual and contextual characteristics. Hazard ratios (HRs) were expressed per increments equal to the 5^th-95^th percentile range of each pollutant distribution.

RESULTS

We analyzed 1,249,108 residents and found strong associations between all exposure indicators and mortality. We observed higher mortality risk with increasing exposure to PM_2.5 absorbance (HR=1.05; 95% CI: 1.03-1.06) and to tracers of non-tailpipe traffic emissions such as tire and brake wear (Cu, Fe, and Zn); for PM_2.5Zn, we found HR=1.06 (95% CI: 1.04-1.08) for non-accidental mortality, HR=1.07 (95% CI: 1.04-1.10) for CVD, and HR=1.11 (95% CI: 1.06-1.16) for IHD mortality. With increasing levels of nickel in PM₁₀, we found HR=1.07 (95% CI: 1.05-1.09) for non-accidental mortality, HR=1.08 (95% CI: 1.05-1.11) for CVD, and HR=1.13 (95% CI: 1.08-1.18) for IHD mortality. Results were robust when we adjusted for PM mass and for cardiovascular mortality when we adjusted for NO₂.

CONCLUSIONS

In addition to vehicular exhaust pollutants, PM related to non-tailpipe emissions and mixed oil burning/industry plays an important role in mortality.

Interplay of adipocyte and hepatocyte: Leptin upregulates hepcidin

Conflicting evidence concerning leptin, an adipocyte-derived hormone, in atherogenesis and non-alcoholic fatty liver disease (NAFLD) has been reported. Iron metabolism and iron-mediated oxidative stress should be taken into consideration for the clarification of the pathogenesis of these diseases. In this study, we demonstrate that leptin receptor activation directly affects iron metabolism by the finding that serum levels of hepcidin, the master regulator of iron in the whole body, were significantly lower in leptin-deficient (ob/ob) and leptin receptor-deficient (db/db) mice. The administration of recombinant leptin to ob/ob mice for two weeks showed a significant increase in serum hepcidin and hepatic Hamp mRNA levels. Hamp mRNA levels were significantly correlated with hepatic iron content and BMP6 mRNA levels. Hepatic iron content was associated with the increase in mRNA levels of divalent metal transporter 1 and transferrin receptor. Our data provide evidence that the interplay of these two hormones could help improve the understanding of the pathogenesis of atherosclerosis and NAFLD.

Oxidative Stress in Human Atherothrombosis: Sources, Markers and Therapeutic Targets

Atherothrombosis remains one of the main causes of morbidity and mortality worldwide. The underlying pathology is a chronic pathological vascular remodeling of the arterial wall involving several pathways, including oxidative stress. Cellular and animal studies have provided compelling evidence of the direct role of oxidative stress in atherothrombosis, but such a relationship is not clearly established in humans and, to date, clinical trials on the possible beneficial effects of antioxidant therapy have provided equivocal results. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is one of the main sources of reactive oxygen species (ROS) in human atherothrombosis. Moreover, leukocyte-derived myeloperoxidase (MPO) and red blood cell-derived iron could be involved in the oxidative modification of lipids/lipoproteins (LDL/HDL) in the arterial wall. Interestingly, oxidized lipoproteins, and antioxidants, have been analyzed as potential markers of oxidative stress in the plasma of patients with atherothrombosis. In this review, we will revise sources of ROS, focusing on NADPH oxidase, but also on MPO and iron. We will also discuss the impact of these oxidative systems on LDL and HDL, as well as the value of these modified lipoproteins as circulating markers of oxidative stress in atherothrombosis. We will finish by reviewing some antioxidant systems and compounds as therapeutic strategies to prevent pathological vascular remodeling.