Zinc supplementation decreases the development of atherosclerosis in rabbits

Growth performance, tissue precipitation, metallothionein and cytokine transcript expression and economics in response to different dietary zinc sources in growing rabbits

The impact of different dietary zinc sources on the growth, serum metabolites, tissue zinc content, economics and relative expression of cytokine and metallothionein genes was evaluated in this study. A total of 120 35-day-old male New Zealand White (NZW) rabbits were randomly distributed into four dietary experimental groups with 10 replicates per group and 3 animals per replicate. The control group was fed basal diet with a Zn-free vitamin-mineral premix; the other three groups received control basal diet supplemented with 50 mg/kg level with zinc oxide (ZnO; as inorganic source), Zn-methionine (Zn-Met; as organic source) and zinc oxide nanoparticles (nano-ZnO). The results indicated that Zn-Met and nano-ZnO groups significantly improved body weight, daily weight gain (DWG), feed conversion ratio (FCR) and nutrient digestibility, as well as decreased mortality, compared to ZnO and control groups. Zn-Met and nano-ZnO significantly reduced serum total cholesterol but did not affect serum proteins and liver function. Nano-ZnO supplemented group also recorded the highest value of serum alkaline phosphatase (ALP), insulin-like growth factor (IGF-1) and lysozymes compared to other groups. Nano-ZnO supplementation had increased hepatic Zn and Cu content and decreased faecal Zn content. Also nano-ZnO group recorded higher expression levels of genes encoding for metallothionein I and metallothionein II, interleukin-2 and interferon-γ in the liver of rabbits. The findings of this study demonstrated zinc nanoparticles, and organic zinc supplementation had improved growth performance and health status of growing rabbits than inorganic zinc oxide.

Quantitative analysis of multiple elements in healthy and remodeled epithelium from human upper airway mucosa using nuclear microscopy

Elements are vital in airway mucosal physiology and pathology, but their distribution and levels in the mucosa remain unclear. This study uses the state-of-the-art nuclear microscopy facility to map and quantify multiple elements in the histology sections of nasal mucosa from patients with nasal polyps or inverted papilloma. Our results demonstrate that P and Ca are the most abundant elements in mucosa and their distinct difference between epithelial and subepithelial regions; more importantly, our results reveal decreased amounts of Cu and Zn in the remodeled epithelium as compared to the normal epithelium. These findings suggest that Cu and Zn may be beneficial targets to regulate aberrant epithelial remodeling in airway inflammation.

Multivariate statistical evaluation of trace metal levels in the blood of atherosclerosis patients in comparison with healthy subjects

BACKGROUND

Numerous epidemiological studies have suggested that metal exposure may promote the atherosclerosis disorder in humans.

OBJECTIVE

This study is carried out to assess the distribution, correlation and multivariate apportionment of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb) and zinc (Zn) in the blood of atherosclerosis patients in comparison with healthy donors.

METHOD

The quantification of metals is done by atomic absorption spectrometry, after wet-acid digestion of the blood samples.

RESULTS

Significantly higher concentrations of cadmium, chromium, copper, iron and manganese are found in the blood of atherosclerosis patients. The correlation study shows diverse relationships among the metals in blood of the patients and controls. Multivariate cluster analysis based on the metal levels in patients and controls reveals clearly separate grouping for the patients and healthy donors. Moreover, principal component analysis shows divergent grouping of the metals for the patients and healthy donors, which may be associated with the altered metabolism of the metals in atherosclerosis patients.

CONCLUSION

Overall, the distribution, correlation and multivariate apportionment of selected metals in atherosclerosis patients and healthy donors are significantly divergent. Hence, present findings suggest that the trace and redox metals accumulated in the body may pose a high risk for atherosclerosis development.

The utility of iron chelators in the management of inflammatory disorders

Since iron can contribute to detrimental radical generating processes through the Fenton and Haber-Weiss reactions, it seems to be a reasonable approach to modulate iron-related pathways in inflammation. In the human organism a counterregulatory reduction in iron availability is observed during inflammatory diseases. Under pathological conditions with reduced or increased baseline iron levels different consequences regarding protection or susceptibility to inflammation have to be considered. Given the role of iron in development of inflammatory diseases, pharmaceutical agents targeting this pathway promise to improve the clinical outcome. The objective of this review is to highlight the mechanisms of iron regulation and iron chelation, and to demonstrate the potential impact of this strategy in the management of several acute and chronic inflammatory diseases, including cancer.

Long-term zinc deprivation accelerates rat vascular smooth muscle cell proliferation involving the down-regulation of JNK1/2 expression in MAPK signaling

BACKGROUND

The accelerated proliferation of vascular smooth muscle cells (VSMCs) is a contributor for atherosclerosis by thickening the vascular wall. Since zinc modulation of VSMC proliferation has not been clarified, this study investigated whether zinc affects VSMC proliferation.

METHODS AND RESULTS

Both a rat aorta origin vascular smooth muscle cell line (A7r5 VSMCs) and primary VSMCs which were collected from rat aorta (pVSMCs) were cultured with zinc (0-50 μM Zn) for short- (≤12 d) and long-term (28 d) periods under normal non-calcifying (0 or 1 mM P) or calcifying (>2 mM P) P conditions. Mouse vascular endothelial cells (MS I cells) were also cultured (under 0-50 μM Zn and 10 mM P for 20 d) to compare with VSMC cultures. While during short-term culture of VSMCs, zinc deprivation decreased cell proliferation in a zinc-concentration manner both under non-calcifying and calcifying conditions in A7r5 and pVSMCs (P < 0.05), during long-term cultures (28 d), A7r5 VSMC proliferation was inversely related to medium zinc concentration under normal physiological P conditions (regression coefficient r(2) = -0.563, P = 0.012). The anti-cell proliferative effect of zinc supplementation (>50 μM) was VSMC-specific. Long-term (35 d), low zinc treatment down-regulated JNK expression and activation, while not affecting ERK1/2 MAPK signaling in A7r5 VSMCs.

CONCLUSION

The results showed that chronic zinc deprivation accelerated VSMC proliferation, perhaps due to down-regulation of MAPK-JNK signaling, and that the anti-cell proliferative role of zinc is VSMC-specific. The findings suggested that zinc may have anti-VSMC proliferative properties in atherosclerosis.

[Manganese in atherogenesis: detection, origin, and role]

The role of transition metal ions in atherogenesis is controversial; they can participate in the hydroxyl radical generation and catalyze the reactive oxygen species neutralization reaction as cofactors of antioxidant enzymes. Using EPR spectroscopy, we revealed that 70% of the samples of aorta with atherosclerotic lesions possessed superoxide dismutase activity, 100% of the samples initiated Fenton reaction and demonstrated the presence of manganese paramagnetic centers. The sodA gene encoding manganese-dependent bacterial superoxide dismutase was not found in the samples of atherosclerotic plaques by PCR using degenerate primers. The data obtained indicates the perspectives of manganese analysis as a marker element in the express diagnostics of atherosclerosis.

Zinc as a feed supplement and its impact on plasma cholesterol concentrations in breeding cocks

The aim of this work was to verify the impact of feed supplemented with selected inorganic and organic zinc compounds on the total cholesterol concentrations and other blood plasma indices in breeding cocks. A total of 250 RIR 05 breeding cocks, 9 weeks old, were used. The cocks were divided into 5 groups of 50 animals each (four experimental groups and one control group). Cocks were fed a commercial feed mixture specifically for breeding cocks, containing 30.4 mg·kg-1 of zinc. The feed for experimental groups of cocks was fortified to 100 mg Zn·kg-1: zinc sulphate in first group, zinc oxide in second group, fodder yeast (Minvital Zn) in third group and Bioplex Zn in fourth group. Blood samples for biochemical examination were taken from the basilic vein. The contents of total cholesterol (Chol), total proteins (TP), glucose (Glu), aspartate aminotransferase (AST), alanine aminotransferase (ALT), calcium (Ca), phosphorus (P) and magnesium (Mg) in blood plasma were spectrophotometrically measured using a biochemical analyser, Cobas EMira, and commercial kits (Biovendor a.s., Czech Republic). In the 15th week of age, third and fourth groups showed a significant (P ≤ 0.05) and highly significant (P ≤ 0.01) decrease of total cholesterol in blood plasma compared to the control. In the 20th and 25th week of age, all of the experimental groups showed a significantand highly significant (P ≤ 0.01) decrease of total cholesterol in blood plasma compared to the control. Other monitored indices (total proteins, glucoses, aspartate aminotransferase, alanine aminotransferase, calcium, phosphorus and magnesium) did not reveal any significant changes between the experimental and the control groups. The presented work provides the first available experimental evidence regarding the impact of zinc supplementation on the cholesterol levels in blood plasma of breeding cocks.

Changes of blood biochemistry in the rabbit animal model in atherosclerosis research; a time- or stress-effect

Background

Rabbits are widely used in biomedical research and especially as animal models in atherosclerosis studies. Blood biochemistry is used to monitor progression of disease, before final evaluation including pathology of arteries and organs. The aim of the present study was to assess the consistency of the biochemical profile of New Zealand White rabbits on standard diet from 3 to 6 months of age, during which they are often used experimentally.

Methods and results

Eight conventional male 3-month-old New Zealand White rabbits were used. Blood samples were taken at baseline, 1, 2 and 3 months later. Plasma glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triacylglycerol concentrations, and alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase activities and malondialdehyde were measured. Statistically significant time-related changes were observed in glucose, total cholesterol and triacylglycerol, which were not correlated with aortic lesions at 6 months of age. Similarly, hepatic enzyme activity had significant time-related changes, without a corresponding liver pathology.

Conclusions

Age progression and stress due to single housing may be the underlying reasons for these biochemistry changes. These early changes, indicative of metabolic alterations, should be taken into account even in short-term lipid/atherosclerosis studies, where age and standard diet are not expected to have an effect on the control group of a study.

Synthetic and natural iron chelators: therapeutic potential and clinical use

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade(®)) and deferiprone (Ferriprox(®)), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry.

Redox pioneer: professor Barry Halliwell

Professor Barry Halliwell is recognized as a Redox Pioneer because he has published eight articles on redox biology that have been each cited more than 1000 times, and 158 articles that have been each cited more than 100 times. His contributions go back as far as 1976, when he was involved in elucidation of the Foyer-Halliwell-Asada cycle, an efficient mechanism for preventing oxidative damage to chloroplasts. His subsequent work established the important role of iron and zinc in free radical reactions and their relevance to human pathologies. Professor Halliwell is also a leader in developing novel methodology for detecting free radical intermediates in vivo, and his contributions to our knowledge of reactive nitrogen species are highly significant. His sustained excellence won him the top-cited scientist award in the United Kingdom in biomedical sciences in 1999, and in 2003 he was recognized as a highly cited scientist by Institute of Scientific Information (ISI) for work on plant antioxidants, and the same year ranked 28 out of 5494 biochemists/biologists for scientific impact. Two pieces of his scholarly work have been listed as Citation Classics by ISI, and in 2007 his laboratory was ranked number 1 worldwide based on highest citation score in research on free radicals.

Multiple aberrations in shared inflammatory and oxidative & nitrosative stress (IO&NS) pathways explain the co-association of depression and cardiovascular disorder (CVD), and the increased risk for CVD and due mortality in depressed patients

There is evidence that there is a bidirectional relationship between major depression and cardiovascular disorder (CVD): depressed patients are a population at risk for increased cardiac morbidity and mortality, and depression is more frequent in patients who suffer from CVD. There is also evidence that inflammatory and oxidative and nitrosative stress (IO&NS) pathways underpin the common pathophysiology of both CVD and major depression. Activation of these pathways may increase risk for both disorders and contribute to shared risk. The shared IO&NS pathways that may contribute to CVD and depression comprise the following: increased levels of pro-inflammatory cytokines, like interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-γ; T cell activation; increased acute phase proteins, like C-reactive protein, haptoglobin, fibrinogen and α1-antitrypsin; complement factors; increased LPS load through bacterial translocation and subsequent gut-derived inflammation; induction of indoleamine 2,3-dioxygenase with increased levels of tryptophan catabolites; decreased levels of antioxidants, like coenzyme Q10, zinc, vitamin E, glutathione and glutathione peroxidase; increased O&NS characterized by oxidative damage to low density lipoprotein (LDL) and phospholipid inositol, increased malondialdehyde, and damage to DNA and mitochondria; increased nitrosative stress; and decreased ω3 polyunsaturated fatty acids (PUFAs). The complex interplay between the abovementioned IO&NS pathways in depression results in pro-atherogenic effects and should be regarded as a risk factor to future clinical CVD and due mortality. We suggest that major depression should be added as a risk factor to the Charlson "comorbidity" index. It is advised that patients with (sub)chronic or recurrent major depression should routinely be assessed by serology tests to predict if they have an increased risk to cardiovascular disorders.

Endothelial metallothionein expression and intracellular free zinc levels are regulated by shear stress

We examined the effects of fluid shear stress on metallothionein (MT) gene and protein expression and intracellular free zinc in mouse aorta and in human umbilical vein endothelial cells (HUVECs). Immunostaining of the endothelial surface of mouse aorta revealed increased expression of MT protein in the lesser curvature of the aorta relative to the descending thoracic aorta. HUVECs were exposed to high steady shear stress (15 dyn/cm(2)), low steady shear stress (1 dyn/cm(2)), or reversing shear stress (mean of 1 dyn/cm(2), 1 Hz) for 24 h. Gene expression of three MT-1 isoforms, MT-2A, and zinc transporter-1 was upregulated by low steady shear stress and reversing shear stress. HUVECs exposed to 15 dyn/cm(2) had increased levels of free zinc compared with cells under other shear stress regimes and static conditions. The increase in free zinc was partially blocked with an inhibitor of nitric oxide synthesis, suggesting a role for shear stress-induced endothelial nitric oxide synthase activity. Cells subjected to reversing shear stress in zinc-supplemented media (50 μM ZnSO(4)) had increased intracellular free zinc, reduced surface intercellular adhesion molecule-1 expression, and reduced monocyte adhesion compared with cells exposed to reversing shear stress in normal media. The sensitivity of intracellular free zinc to differences in shear stress suggests that intracellular zinc levels are important in the regulation of the endothelium and in the progression of vascular disease.

Differential effect of Pistacia vera extracts on experimental atherosclerosis in the rabbit animal model: an experimental study

Background

Lipid-enriched diets and oxidative stress are risk factors for the development of atherosclerosis. The effects of the methanolic (ME) and cyclohexane (CHE) extracts of the Pistacia vera nut, often included in the Mediterranean diet, were studied in the rabbit model of atherosclerosis.

Methods and results

Twenty-four New Zealand White rabbits received atherogenic diet (Control Group), supplemented with ME (Group ME) or CHE (Group CHE) for 3 months. Previously, a GC-MS and a UHPLC LC-DAD-ESI(-)-HRMS/MS method were developed to investigate the extracts' chemical profiles. Blood samples at baseline and monthly determined lipid profile, lipid peroxidation and liver function. The aorta, myocardium and liver were examined histologically at 3 months.

Groups ME and CHE had significantly higher HDL- and non-significantly lower LDL-cholesterol median % changes from baseline than the Control Group. Triacylglycerol was significantly higher in Group CHE vs. Control. MDA values were significantly lower in Group ME vs. Control and CHE. ALT and AST were significantly higher in Group CHE vs. Control. γ-GT was lower in Group ME vs. Control. Aortic intimal thickness was significantly less in Groups ME and CHE vs. Control; Group ME atherosclerotic lesions were significantly less extensive vs. Groups Control and CHE. Only Group CHE had significant liver fatty infiltration.

Conclusions

During short-term administration concomitantly with atherogenic diet, both P. vera extracts were beneficial on HDL-, LDL-cholesterol and aortic intimal thickness. The ME additionally presented an antioxidant effect and significant decrease of aortic surface lesions. These results indicate that P. vera dietary inclusion, in particular its ME, is potentially beneficial in atherosclerosis management.

Zinc accumulation in heterozygous mutants of fumble, the pantothenate kinase homologue of Drosophila

Coenzyme A (CoA) functions in the intracellular trafficking of acetyl groups. In humans, mutations in the pantothenate kinase-2 gene, which encodes a key enzyme in CoA biosynthesis, are associated with neurodegeneration and premature death. Diagnosis is based on iron accumulation in the globus pallidus observed by magnetic resonance imaging. We investigated the elemental composition of the fumble mutant, a model of the human disease. Surprisingly, flies carrying a fumble loss-of-function allele had a three-fold increase in total zinc levels per dry weight when compared to control strains, but no change in total iron, copper or manganese levels. Accordingly, zinc supplementation had an adverse impact on the development of fumble mutant larvae, but zinc chelation failed to protect.

The wanderings of a free radical

In my career I have moved from chemistry to biochemistry to plant science to clinical chemistry and back again (in a partial way) to plants. This review presents a brief history of my research achievements (ascorbate-glutathione cycle, role of iron in oxidative damage and human disease, biomarkers of free radical damage, and studies on atherosclerosis and neurodegeneration) and how they relate to my research activities today. The field of free radicals/other reactive species/antioxidants underpins all of modern Biology. These agents helped to drive human evolution and the basic principles of the field are repeatedly found to be relevant in other research areas. It was an exciting field when I started some 40 years ago, and it still is today, but some major challenges must be faced.

Modification with homocysteine does not increase susceptibility of human low-density lipoprotein to iron-mediated oxidation

Oxidation of human low-density lipoprotein (LDL) is centrally involved in the development of cardiovascular diseases. This study investigated whether homocysteine-mediated thiolation of LDL rendered it more susceptible to oxidation by iron. After in vitro exposure to homocysteine thiolactone for 60 minutes, LDL's thiol content increased from 26 +/- 5 (control) to 224 +/- 20 nmol/mg of protein (thiolated; P < .0001). Control and thiolated LDL (0.2 mg of protein per milliliter) were incubated with either redox active iron (Fe(3+); 10 micromol/L) or, as a positive control, copper (Cu(2+); 10 micromol/L). Consistent with the observation of others, thiolation decreased Cu(2+)-dependent formation of lipid oxidation products in LDL (17 +/- 16 nmol/mg of protein formed in thiolated LDL, compared with 81 +/- 21 nmol/mg of protein in control, during 6 hours of incubation; P < .01). Thiolation had no effect, however, on Fe(3+)-mediated oxidation of LDL with lipid oxidation products remaining essentially nondetectable during prolonged incubation (up to 48 hours). Thiolation similarly had no effect on oxidation of LDL (0.2 mg of protein per milliliter) by heme-complexed iron (hemin; 10 micromol/L), with lipid oxidation products increasing to 24 +/- 1 and 27 +/- 4 nmol/mg of protein for control and thiolated LDL, respectively, during 6 hours of incubation (P > .05). Similar results were observed using LDL with varying degrees of thiolation (29 +/- 5, 85 +/- 14, 130 +/- 15, and 213 +/- 19 nmol of thiol per milligram of protein). In conclusion, these results demonstrate that thiolation has no effect on LDL's susceptibility to iron-mediated oxidation.

Pro-inflammatory genetic background and zinc status in old atherosclerotic subjects

Inflammation and genetics are prominent mechanisms in the pathogenesis of atherosclerosis (AT) and its complications. In this review we discuss the possible impact on AT development of several genetic determinants involved in inflammation, oxidative stress and cytoprotection (IL-6, TNF-alpha, IL-10, CD14, TLR4, MT, HSP70). Genetic polymorphisms of these genes may affect a differential inflammatory response predisposing to AT. However, allelic polymorphisms of genes which increase the risk of AT frequently occur in the general population but, only adequate gene-environment-polymorphism interactions promote the onset of the disease. Zinc deficiency has been suggested as an environmental risk factor for AT. With advancing age, the incidence of zinc deficiency increases for several reasons. Among them, dietary intake, malabsorption and genetic background of inflammatory markers may be involved. A crucial contribution may also be played by increased oxidative stress which may lead to the appearance of dysfunctional proteins, including metallothioneins (MT) that are in turn involved in zinc homeostasis. The detection of candidate genes related to inflammation and promoting AT and their reciprocal influence/interaction with zinc status might allow earlier appropriate dietary interventions in genetically susceptible subjects.

Accumulation of Zinc in Human Atherosclerotic Lesions Correlates With Calcium Levels But Does Not Protect Against Protein Oxidation

Objective— Oxidized lipids and proteins, as well as decreased antioxidant levels, have been detected in human atherosclerotic lesions, with oxidation catalyzed by iron and copper postulated to contribute to lesion development. Zinc has been postulated to displace iron from critical sites and thereby protect against damage. In this study, metal ion and protein oxidation levels were quantified in human carotid and abdominal artery specimens containing early-to-advanced lesions, to determine whether zinc concentrations correlate inversely with iron levels and protein oxidation.

Methods and Results— Metal ions were quantified by EPR and inductively coupled plasma mass spectroscopy. Native and oxidized protein side-chains were quantified by high-performance liquid chromatography. Elevated levels of zinc (≈6-fold) were detected in advanced lesions compared to healthy tissue or early lesions. Zinc did not correlate negatively with iron or copper levels suggesting that zinc does not displace these metal ions. Highly significant positive correlations ( P <0.005) were detected between zinc and calcium levels.

Conclusions— Zinc did not correlate with low iron levels and reduced protein oxidation. These data indicate that zinc does not prevent protein oxidation in advanced lesions. The reported protective effect of zinc accumulation is proposed to be associated with lesion calcification.

Extracellular superoxide dismutase (ecSOD) in vascular biology: an update on exogenous gene transfer and endogenous regulators of ecSOD

Extracellular superoxide dismutase (ecSOD) is the major extracellular scavenger of superoxide (O(2)(.-)) and a main regulator of nitric oxide (NO) bioactivity in the blood vessel wall, heart, lungs, kidney, and placenta. Involvement of O(2)(.-) has been implicated in many pathological processes, and removal of extracellular O(2)(.-) by ecSOD gene transfer has emerged as a promising experimental technique to treat vascular disorders associated with increased oxidant stress. In addition, recent studies have clarified mechanisms that regulate ecSOD expression, tissue binding, and activity, and they have provided new insight into how ecSOD interacts with other factors that regulate vascular function. Finally, studies of a common gene variant in humans associated with disruption of ecSOD tissue binding suggest that displacement of the enzyme from the blood vessel wall may contribute to vascular diseases. The purpose of this review is to summarize recent research findings related to ecSOD function and gene transfer and to stimulate other investigations into the role of this unique antioxidant enzyme in vascular pathophysiology and therapeutics.

Macrophage iron, hepcidin, and atherosclerotic plaque stability

Hepcidin has emerged as the key hormone in the regulation of iron balance and recycling. Elevated levels increase iron in macrophages and inhibit gastrointestinal iron uptake. The physiology of hepcidin suggests an additional mechanism by which iron depletion could protect against atherosclerotic lesion progression. Without hepcidin, macrophages retain less iron. Very low hepcidin levels occur in iron deficiency anemia and also in homozygous hemochromatosis. There is defective retention of iron in macrophages in hemochromatosis and also evidently no increase in atherosclerosis in this disorder. In normal subjects with intact hepcidin responses, atherosclerotic plaque has been reported to have roughly an order of magnitude higher iron concentration than that in healthy arterial wall. Hepcidin may promote plaque destabilization by preventing iron mobilization from macrophages within atherosclerotic lesions; the absence of this mobilization may result in increased cellular iron loads, lipid peroxidation, and progression to foam cells. Marked downregulation of hepcidin (e.g., by induction of iron deficiency anemia) could accelerate iron loss from intralesional macrophages. It is proposed that the minimally proatherogenic level of hepcidin is near the low levels associated with iron deficiency anemia or homozygous hemochromatosis. Induced iron deficiency anemia intensely mobilizes macrophage iron throughout the body to support erythropoiesis. Macrophage iron in the interior of atherosclerotic plaques is not exempt from this process. Decreases in both intralesional iron and lesion size by systemic iron reduction have been shown in animal studies. It remains to be confirmed in humans that a period of systemic iron depletion can decrease lesion size and increase lesion stability as demonstrated in animal studies. The proposed effects of hepcidin and iron in plaque progression offer an explanation of the paradox of no increase in atherosclerosis in patients with hemochromatosis despite a key role of iron in atherogenesis in normal subjects.

Promotion of atherogenesis by copper or iron—Which is more likely?

Iron levels increase in atherosclerotic lesions in cholesterol fed-rabbits and play a role in atherosclerosis. We investigated whether copper also rises. Male New Zealand White rabbits were fed high-cholesterol diets for 8 weeks. After sacrifice, lesion sizes were determined, and elemental analyses of the lesion and unaffected artery wall performed using nuclear microscopy. Unlike iron, lesion copper is decreased by about half compared with the unaffected artery wall, and much less copper than iron is present. Our data suggest that iron may be more likely to play a role in the promotion of atherosclerosis than copper.