Serum ferritin and ceruloplasmin as coronary risk factors

Copper, oxidative stress, and human health

Copper (Cu), a redox active metal, is an essential nutrient for all species studied to date. During the past decade, there has been increasing interest in the concept that marginal deficits of this element can contribute to the development and progression of a number of disease states including cardiovascular disease and diabetes. Deficits of this nutrient during pregnancy can result in gross structural malformations in the conceptus, and persistent neurological and immunological abnormalities in the offspring. Excessive amounts of Cu in the body can also pose a risk. Acute Cu toxicity can result in a number of pathologies, and in severe cases, death. Chronic Cu toxicity can result in liver disease and severe neurological defects. The concept that elevated ceruloplasmin is a risk factor for certain diseases is discussed. In this paper, we will review recent literature on the potential causes of Cu deficiency and Cu toxicity, and the pathological consequences associated with the above. Finally, we will review some of the potential biochemical lesions that might underlie these pathologies. Given that oxidative stress is a characteristic of Cu deficiency, the role of Cu in the oxidative defense system will receive special attention. The concept that excess Cu may be a precipitating factor in Alzheimer's disease is discussed.

High cardiovascular risk in young Saudi males: cardiovascular risk factors, diet and inflammatory markers

BACKGROUND

The relationship between coronary risk score (CRS), individual coronary risk factors and the serum inflammatory markers, high sensitivity C-reactive protein (hsCRP), ceruloplasmin (Cp), and soluble intercellular adhesion molecule-1 (sICAM-1) was studied in 140 Saudi males without clinically evident coronary heart disease (CHD).

METHODS

One hundred forty subjects without clinically evident CHD were categorized into age tertiles. Demographic data together with an estimate of CRS using Framingham and PROCAM algorithms were obtained, and serum lipid profile, glucose, hsCRP, sICAM-1, and Cp were measured. Macronutrient intake was assessed by a questionnaire. The relationship between CRS, biochemical markers and diet was assessed by univariate and multivariate analysis.

RESULTS

There was no significant difference in median hsCRP, sICAM-1 or Cp between the age groups. Serum Cp was positively associated with age (r=0.224, p<0.01) and FRS score (r=0.174, p<0.05). Serum sICAM-1 was negatively associated with PROCAM score (r=-0.183, p<0.05). sICAM-1 was positively associated with HDL cholesterol (r=0.36, p<0.0001) among non-diabetics and negatively associated (r=-0.397, p<0.05) among diabetic subjects. Age and dietary intake of saturated fatty acids together explained 7.9% of the variation in serum Cp level in a stepwise multiple regression model. Similarly 6.5% of the variation in serum sICAM-1 level was explained by the total cholesterol/HDL-C ratio. The youngest tertile of the group (<30 y) had the highest dietary intake of energy, fat and saturated fatty acids (p<0.05), and also had a high prevalence of obesity, smoking and sedentary lifestyle.

CONCLUSION

We have demonstrated that there is a high prevalence of coronary risk factors and poor dietary intake within a Saudi male population, and that dietary factors are associated with serum sICAM-1 and ceruloplasmin but not hsCRP concentrations in this group.

Ferritin in atherosclerosis

Iron, an essential element for many important cellular functions in all living organisms, can catalyze the formation of potentially toxic free radicals. Excessive iron is sequestered by ferritin in a nontoxic and readily available form in a cell. Ferritin is composed of 24 subunits of different proportions of two functionally distinct subunits: ferritin H and L. The former is involved in ferroxidase activity necessary for iron uptake and oxidation of ferrous iron, while the latter is involved in nucleation of the iron core. The expression of ferritin is under delicate control and is regulated at both the transcriptional and posttranscriptional levels by iron, cytokines and oxidative stress. Elevated ferritin levels are associated with an increased risk of atherosclerotic coronary artery disease (CAD), the leading cause of death and illness in developed countries. Serum ferritin levels are a good indicator of iron stores in the body. In fact, epidemiological studies have suggested that elevated serum ferritin levels are associated with an increased risk of CAD and myocardial infarction (MI), though inconsistent results were obtained in some other studies. Moreover, recent proteomics and molecular biology studies have shown that ferritin levels in arteries are increased in diseased tissues, which further supports the link of ferritin to CAD/MI. Future studies will determine whether increased ferritin levels can serve as a distinct biomarker for the incidence of CAD/MI and distinguish whether increased ferritin levels are a cause of CAD or a consequence of the disease process.

Effect of statin therapy on serum trace element status in dyslipidaemic subjects

Patients previously not treated with a lipid-lowering agent (n = 20; mean age 49.15 +/- 3.28 years) were treated with either 10 mg/day of Simvastatin (n = 11), or Atorvastatin (n = 9) for 4 months. Fourteen additional patients were recruited from the same clinic at the same hospital as a control group. The medication of these latter patients was unaltered for 4 months and the same parameters were measured as for the statin groups. Serum concentrations of zinc, copper, caeruloplasmin, selenium, glutathione peroxidase (GPx) and C-reactive protein (CRP) were measured together with their lipid profiles pre- and post-treatment. In addition to reducing serum total and low-density lipoprotein (LDL) cholesterol (p < 0.0001), statin treatment was associated with a significant reduction in mean serum zinc (9%, p = 0.03), copper (9%, p < 0.01), caeruloplasmin (24%, p < 0.05), and median CRP (45%, p < 0.03). Similar changes were not observed in the control patients. No significant effects were observed for serum selenium, copper/caeruloplasmin ratio, or GPx (p > 0.05) in either statin or control groups. These changes may be related to the known anti-inflammatory properties of the statin class of drugs.

Intracellular Labile Iron Modulates Adhesion of Human Monocytes to Human Endothelial Cells

OBJECTIVE

Elevated iron stores and high plasma iron concentration have been linked to an increased risk of atherosclerosis. Iron may thereby affect the interaction of monocytes to endothelium, an initial event in the formation of atherosclerotic plaques.

METHODS AND RESULTS

Addition of 10 mumol/L non-transferrin-bound iron to the incubation medium caused a 2-fold increase in monocyte adhesion to human umbilical vein endothelial cells (HUVECs). A concordant increase in the expression of the following adhesion molecules was observed: vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and endothelial selectin on HUVECs as well as very late antigen-4, and lymphocyte function-associated antigen-1 on monocytes. The inclusion of either deferiprone or salicylaldehyde isonicotinoylhydrazone counteracted these effects. Intracellular iron chelation by deferoxamine was completed only after 10 hours of incubation, shown by reversal of iron-quenched intracellular calcein signal, and concurrently the effects of iron were blunted. The membrane-impermeable chelator, diethylenetriamine pentaaceticacid, failed to negate iron effects, even after 48 hours of treatment. Furthermore, only membrane-permeable superoxide or hydroxyl radical scavengers were capable of preventing HUVEC activation by iron.

CONCLUSIONS

Non-transferrin-bound iron increases the level of intracellular labile iron, which promotes monocyte recruitment to endothelium and may thereby contribute to the pathogenesis of atherosclerosis. Iron-induced adhesion molecule expression was observed, and this event may involve the production of oxygen radicals.

Serum Ferritin in Chronic Kidney Disease: Reconsidering the Upper Limit for Iron Treatment

Intravenous iron treatment in hemodialysis patients improves the response to recombinant human erythropoietin (rHuEPO) and facilitates achievement of targets for hemoglobin and hematocrit. Excessive treatment, however, could expose patients to risks related to iron overload and oxidative stress. Therefore international treatment guidelines generally recommend that intravenous iron be discontinued when serum ferritin is greater than 500-1000 ng/ml. In this article we explore the relevant issues that inform the decisions as to what levels of serum ferritin are used as the upper limit for treatment. We conclude that the current published literature is inadequate for developing evidence-based guidelines. Clinical judgment is critical to properly weigh the risks and benefits of intravenous iron treatment in the context of the individual patient.

Anemia as a risk factor for cardiovascular disease

In the present review we examine the physiologic response to chronic anemia and describe potential adverse effects of anemia on myocardial and large arterial remodeling. We present observational data demonstrating that anemia is a risk factor for cardiovascular disease (CVD) outcomes in patients with chronic kidney disease and patients with heart failure. We also present data that have evaluated the relationship of level of hematocrit to CVD outcomes in patients with ischemic heart disease and in patients in the general population. The results from the latter studies have been inconclusive and have been limited by lack of knowledge of the cause of anemia. This is potentially important because iron deficiency anemia may, in fact, improve endothelial function. We conclude that additional randomized controlled trials of treatment of anemia are needed in chronic kidney disease and patients with heart failure; however, further exploration of the cause of anemia and the effect of different types of anemia on various CVD outcomes are needed in patients with ischemic heart disease and patients in the general population.

Value of serum ferritin and soluble transferrin receptor for prediction of coronary artery disease and its clinical presentations

We investigated whether there is an association between serum ferritin or soluble transferrin receptor (sTfR) concentrations and coronary artery disease (CAD) or its clinical presentations. This is a case-control study that included 892 patients (664 cases with angiographically proven CAD and 228 controls without CAD). Blood was collected before angiography for determination of sTfR, ferritin and C-reactive protein (CRP). The values (median, 25th-75th percentiles) of sTfR (2.6 [2.1; 3.2]mg/l versus 2.4 [2.1; 3.0]mg/l, P = 0.13) or ferritin (140.1 [74.8; 248.3]ng/ml versus 120.1 [74.9; 218.0]ng/ml, P = 0.11) did not differ significantly between cases or controls. The values of sTfR in the case subjects with 1-vessel, 2-vessel, and 3-vessel CAD were: 2.4 [2.0; 3.0], 2.6 [2.0; 3.2], and 2.8 [2.2; 3.3]mg/l, respectively (P = 0.003). In multivariate analysis, neither sTfR (chi2 = 0.14, P = 0.70) nor ferritin (chi2 = 2.8, P = 0.09) correlated independently with the presence of CAD. In case subjects with stable angina, unstable angina, and acute myocardial infarction (MI), ferritin concentrations were: 127.5 [69.5; 214.0], 138.9 [86.1; 278.0], and 175.0 [93.5; 314.5]ng/ml, respectively (P < 0.001). Our results showed that serum concentrations of sTfR or ferritin do not predict the risk for coronary artery disease. In subjects with pre-existing CAD, those with more severe disease had increased levels of sTfR. Patients with CAD presenting with acute coronary syndromes showed increased levels of serum ferritin.

Safety in iron management

Intravenous (IV) iron therapy has become an integral part of hemodialysis management during the past several decades, and the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines recognize that most patients undergoing hemodialysis will require IV iron therapy on a regular basis to reach target hemoglobin (Hgb) levels. There now are three IV iron compounds available in the United States: iron dextran, sodium ferric gluconate, and iron sucrose. Although all have been proven effective for increasing Hgb/hematocrit levels, recent data show differences in their relative safety profiles. During the past two decades, more than 30 deaths have been attributed to the use of IV iron dextran. The two newer compounds available in the United States, sodium ferric gluconate and iron sucrose, have more favorable safety profiles, with the largest prospective safety comparison to date showing sodium ferric gluconate to be similar to placebo in the incidence of serious anaphylactoid-type reactions. This article reviews safety data surrounding the IV iron therapies.

Dietary factors associated with the risk of high iron stores in the elderly Framingham Heart Study cohort

BACKGROUND

High body iron stores may increase the risk of several chronic diseases. Whether dietary factors contribute to the risk of high iron stores is unknown.

OBJECTIVE

We assessed the relation between dietary factors and the risk of high iron stores in the elderly Framingham Heart Study cohort.

DESIGN

We examined the relation between the usual intake of dietary factors (food-frequency questionnaire) and the risk of high iron stores (serum ferritin >300 and 200 micro g/L in men and women, respectively) in 614 subjects aged 68-93 y.

RESULTS

The risk of high iron stores was significantly higher 1) in subjects who took > or =30 mg supplemental Fe/d than in nonusers [odds ratio (OR): 4.32; 95% CI: 1.63, 11.47], 2) in subjects who consumed >21 servings of fruit/wk than in those who consumed < or =14 servings/wk (OR: 2.88; 95% CI: 1.26, 6.61), and 3) in subjects who consumed >4 but <7 or > or=7 servings of red meat/wk than in those who consumed < or =4 servings/wk (ORs: 2.94 and 3.61, respectively; 95% CIs: 1.33, 6.47 and 1.57, 8.27, respectively). Whole-grain intake (>7 servings/wk) was inversely associated (OR: 0.23; 95% CI: 0.07, 0.75).

CONCLUSIONS

Among elders, intakes of highly bioavailable forms of iron (supplemental iron and red meat) and of fruit, a dietary source of an enhancer of nonheme-iron absorption (vitamin C), promote high iron stores, whereas foods containing phytate (whole grains) decrease these stores. Individual dietary patterns may be important modulators of high iron stores.

Relationship of serum ferritin with cardiovascular risk factors and inflammation in young men and women

Elevated ferritin levels have been reported as a risk factor for coronary heart disease in Finnish and Italian studies. Studies in other populations have found no association between ferritin and cardiovascular disease raising the possibility of confounding with other cardiovascular risk factors. We determined ferritin levels, metabolic cardiovascular risk factors, C-reactive protein (CRP), anthropometric measurements and blood pressure in 815 men and women aged 26 years. In women serum ferritin correlated with CRP, waist measurement, body mass index (BMI), and triglycerides. In multiple regression analysis CRP alone was independently associated with serum ferritin. Serum ferritin in men correlated with waist measurement, BMI, triglycerides and high-density lipoprotein (HDL) cholesterol. After adjustment for the other variables, waist measurement was the only independent predictor of ferritin. Ferritin levels in young men and women are associated with obesity and serum triglycerides, HDL cholesterol in men and inflammation in women. Confounding may contribute to reports of associations between ferritin and cardiovascular disease.

Association of Increased Ferritin with Premature Coronary Stenosis in Men

Background: Body iron status has been implicated in atherosclerotic cardiovascular disease. The main hypothesis is that high iron status is associated with increased oxidation of LDL. We investigated the potential role of ferritin as an additional risk factor promoting atherosclerosis among a young population with coronary artery disease (CAD).

Methods: Four hundred consecutive patients (218 males, 182 females) referred for diagnostic coronary angiography were examined, and risk factors for CAD, lipids, C-reactive protein (CRP), and ferritin concentrations were recorded for all participants.

Results: Ferritin was higher in the male patients with CAD (121 μg/L; range, 56–258 μg/L) than in the men without significant CAD (73 μg/L; range, 32–138 μg/L; P &lt;0.002). Multiple logistic regression analysis, after adjustment for the established coronary risk factors, showed ferritin as an independent discriminating risk factor for CAD (P &lt;0.01). Men in the highest quartile of ferritin had an odds ratio (OR) of 1.62 [95% confidence interval (95% CI), 1.12–2.42; P &lt;0.01] compared with men in the lowest quartile of ferritin. The association between ferritin and CAD was more pronounced in male patients ≤50 years (OR = 2.65; 95% CI, 1.35–5.51; P &lt;0.003). Ferritin was significantly higher in diabetic male patients in comparison with nondiabetic male patients [168 μg/L (range, 74–406 μg/L) vs 106 μg/L (range, 44–221 μg/L), respectively; P &lt;0.002]. No association was observed between ferritin and CAD among the female patients.

Conclusion: Our data suggest that increased ferritin might be an independent predictor of premature CAD in male Iranian patients.

Aspirin intake and the use of serum ferritin as a measure of iron status

BACKGROUND

Atherosclerosis, a primary cause of myocardial infarction (MI), is an inflammatory disease. Aspirin use lowers risk of MI, probably through antithrombotic and antiinflammatory effects. Because serum ferritin (SF) can be elevated spuriously by inflammation, reported associations between elevated SF, used as an indicator of iron stores, and heart disease could be confounded by occult inflammation and aspirin use if they affect SF independently of iron status.

OBJECTIVE

We tested the hypothesis that aspirin use is associated with reduced SF.

DESIGN

We used analysis of covariance to investigate the relation between SF and categories of aspirin use in 913 elderly participants aged 67-96 y in the Framingham Heart Study.

RESULTS

After adjustment for sex, age, body mass index, smoking, alcohol use, concentrations of C-reactive protein and liver enzymes, white blood cell count, and use of nonaspirin nonsteroidal antiinflammatory drugs and other medications, subjects who took >7 aspirins/wk had a significantly lower (by 25%) geometric mean SF than did nonusers, who took <1 aspirin/wk (71 compared with 95 microg/L, respectively; P for trend = 0.004). This effect of aspirin on SF was more marked in diseased subjects than in healthy subjects (mean SF was 50% lower compared with 21% lower, respectively).

CONCLUSIONS

Aspirin use is associated with lower SF. We suggest this effect results from possible increased occult blood loss and a cytokine-mediated effect on SF in subjects with inflammation, infection, or liver disease. The relations between aspirin, inflammation, and SF may confound epidemiologic associations between elevated SF, as an indicator of iron stores, and heart disease risk.

Iron, infection and the evolutionary ecology of heart disease

Levels of iron intake and stored iron have been implicated as risk factors for coronary heart disease. More recently, considerable interest has centered on the role of a variety of infectious pathogens, particulary bacterial pathogens, in the development of artherosclerosis and heart disease. The mechanism whereby elevated iron levels increase the risk of coronary heart disease is not well understood. Here it is proposed that the influence of iron levels on the persistence, pervasiveness and intensity of bacterial infections may play an important role in the development of coronary heart disease.

Joint effects of C-reactive protein and other risk factors on acute coronary events

BACKGROUND

Elevated serum C-reactive protein (CRP) is a predictor of coronary heart disease in population samples. We studied the contribution of the simultaneous presence (joint effects) of elevated CRP and the classic as well as some new risk factors on acute coronary events.

METHODS

With a nested case-control design and logistic regression analyses, we measured baseline and pre-event CRP levels in patients who had myocardial infarction or coronary death (cases) during an 8.5-year follow-up in the Helsinki Heart Study, a coronary primary prevention trial in dyslipidemic middle-aged men. The control patients were participants remaining free of coronary events.

RESULTS

Baseline and pre-event CRP levels were higher in cases than in control patients (4.4 vs 2.0 mg/L, P <.001 and 6.0 vs 3.6 mg/L, P <.001). The relative risk attributed to elevated CRP was 40% higher with chronic elevation (odds ratio [OR], 3.34) compared with high baseline (OR, 2.24) or pre-event (OR, 2.26) level only. Hypertension, low high-density lipoprotein cholesterol, and high leukocyte count increased the risk only marginally without simultaneous occurrence of high CRP, whereas the joint effects of CRP and these classic risk factors suggested additive effects on coronary risk. In contrast, high levels of immunoglobulin G-class antibodies to oxidized low-density lipoprotein and antiprothrombin antibodies as well as high total immunoglobulin G level increased the risk irrespective of CRP.

CONCLUSIONS

Elevated CRP enhances the risks attributed to classic coronary risk factors.

A prospective study of coronary heart disease and the hemochromatosis gene (HFE) C282Y mutation: the Atherosclerosis Risk in Communities (ARIC) study

Increased iron stores may play a role in the development of coronary heart disease (CHD) by increasing lipoprotein oxidation. Recently, mutations have been discovered in the gene (HFE) for hereditary hemochromatosis, an autosomal recessive condition of disordered iron metabolism, absorption, and storage. It is possible that people who carry HFE mutations have increased risk of CHD. We used a prospective case-cohort design (243 CHD cases and 535 non-cases) to determine whether the HFE C282Y mutation was associated with incident CHD in a population-based sample of middle-aged men and women. The frequencies of homozygosity and heterozygosity for the C282Y mutation in the ARIC study population were 0.2% (one homozygous person) and 6%, respectively. The C282Y mutation was associated with nonsignificantly increased risk of CHD (relative risk=1.60, 95% CI 0.9-2.9). After adjusting for other confounding risk factors (age, race, gender, ARIC community, smoking status, diabetes status, hypertension status, LDL cholesterol, HDL cholesterol, and triglycerides), the association became stronger (relative risk=2.70, 95% CI 1.2-6.1). However, a sensitivity analysis showed that this estimate of relative risk was somewhat unstable due to few subjects in some strata. Our prospective findings suggest that individuals carrying the HFE C282Y mutation may be at increased risk of CHD.

Blood donations and risk of coronary heart disease in men

BACKGROUND

In experimental animals, iron overload appears to promote atherosclerosis and ischemic myocardial damage, but the results of epidemiological studies that relate iron stores to risk of coronary heart disease (CHD) have been inconsistent.

METHODS AND RESULTS

We prospectively studied blood donations, which effectively reduce body iron stores, in relation to the risk of CHD among participants in the Health Professionals Follow-up Study. The lifetime history of blood donation was assessed with a questionnaire in 1992. The 38 244 men who were free of diagnosed cardiovascular disease at that time were included in the analyses. During 4 years of follow-up, we documented 328 nonfatal myocardial infarctions and 131 coronary deaths. Although the number of lifetime blood donations was strongly associated with lower plasma ferritin levels in a subsample, the blood donation was not associated with risk of myocardial infarction or fatal CHD. The age-adjusted relative risk (RR) of myocardial infarction for men in the highest category of blood donations (>/=30) compared with never donors was 1.2 (95% CI 0. 8 to 1.8), and this RR was not materially changed after adjustment for several coronary risk factors. No significant associations were found between blood donation and the risk of myocardial infarction in analyses restricted to men with hypercholesterolemia or those who never used antioxidant supplements or aspirin.

CONCLUSIONS

The study results do not support the hypothesis that reduced body iron stores lower CHD risk.

Serum ferritin and death from all causes and cardiovascular disease: the NHANES II Mortality Study. National Health and Nutrition Examination Study

PURPOSE

The purpose of this study was to assess the association between serum ferritin and death from all causes, cardiovascular diseases (CVD), CHD and myocardial infarction (MI). Positive body iron stores have been proposed as a risk factor for coronary heart disease (CHD). While most epidemiologic studies using serum ferritin and other measures of body iron stores have not found an association between iron and heart disease risk, the hypothesis remains controversial. As a result, we examined the relationship of serum ferritin, the principle blood measure of body iron stores, to risk of death in a cohort with a standardized exam and long follow-up.

METHODS

The baseline data for this prospective cohort study were collected in 1976-1980 as part of the second National Health and Nutrition Examination Study (NHANES II) with mortality follow-up using the National Death Index (NDI) through December 31, 1992. The analytic sample (n = 1604) consisted of 128 black men, 658 white men, 100 black women and 718 white women 45-74 years of age at baseline who, based on self-reported data, were free of coronary heart disease at baseline and had no missing data. The main outcome measures were the relative risk of death for persons with serum ferritin levels: <50 microg/L; or 100-199 microg/L; or > or =200 microg/L was compared to persons with serum ferritin levels of 50-99 microg/L adjusted for possible confounding using the Cox proportional hazards model.

RESULTS

Most of the deaths were among white men (n = 254) and women (n = 168). There were relatively few deaths among black men (n = 50) and too few in women (n = 23) to reliably model. The largest number of CVD (n = 119), CHD (n = 82), and MI (n = 49) deaths were in white men while there were 69 CVD, 45 CHD and 13 MI deaths in white women. Black men with a serum ferritin level of <50 microg/L had a significantly higher adjusted risk of death from all causes (RR = 3.1 with 95% confidence limits of 1.5-6.5). There were no other statistically significant associations for all causes mortality for the other three race/sex groups. Additionally, there were no statistically significant associations between serum ferritin and any of the cardiovascular endpoints for any of the groups. There was an apparent but nonsignificant u-shaped association between serum ferritin and all causes mortality in black men and between serum ferritin and CVD death in white women. However, in both cases very wide confidence limits preclude further interpretation.

CONCLUSIONS

Overall, the results do not support the hypothesis that positive body iron stores, as measured by serum ferritin, are associated with an increased risk of CVD, CHD or MI death or between serum ferritin and all causes mortality. Most of the research to date with serum ferritin has been conducted in European men or in European American men. Our results are consistent with the primarily negative results for that race/sex group. More research is needed in women and minority groups, including an explanation of why such an association would exist in these groups but not in white men before an association can be established in them.

Iron stores and coronary artery disease: a clinical application of a method to incorporate measurement error of the exposure in a logistic regression model

Rates of coronary artery disease (CAD) increase sharply after menopause. We examined the hypotheses that high iron stores, as measured by plasma ferritin levels, are a risk factor for CAD and that the increase in iron stores after menopause is at least in part responsible for the rise in CAD in women. We also investigated measurement error of plasma ferritin using a Bayesian conditional independence model and incorporated it into the estimation of the odds ratio (OR) for males. Cases had >/=1 coronary artery stenosis >/=70%. Controls had no visible coronary lesions on angiography. The median plasma ferritin level was 48 mg/L (interquartile range: 28 to 86) among 244 cases and 45 mg/l (24 to 85) among 140 controls. The multivariate analyses among females, males, and females and males combined did not support an association between plasma ferritin levels and CAD (OR for one unit change in log ferritin 1.01, 95% CI 0.71-1.44, OR 0.95, 95% CI 0.66-1.37 and OR 0.95, 95% CI 0.75-1.21, respectively). Accounting for the measurement error of ferritin in males slightly improved the precision of the estimate of the OR but did not unmask an association (OR: 0.94, 95% CI 0.69-1.30). We conclude that high ferritin levels before or after menopause are not associated with CAD. Measurement error might be considered in situations where a one-time measurement is assumed to be representative of long-term exposure.

Ceruloplasmin and cardiovascular disease

Transition metal ion-mediated oxidation is a commonly used model system for studies of the chemical, structural, and functional modifications of low-density lipoprotein (LDL). The physiological relevance of studies using free metal ions is unclear and has led to an exploration of free metal ion-independent mechanisms of oxidation. We and others have investigated the role of human ceruloplasmin (Cp) in oxidative processes because it the principal copper-containing protein in serum. There is an abundance of epidemiological data that suggests that serum Cp may be an important risk factor predicting myocardial infarction and cardiovascular disease. Biochemical studies have shown that Cp is a potent catalyst of LDL oxidation in vitro. The pro-oxidant activity of Cp requires an intact structure, and a single copper atom at the surface of the protein, near His(426), is required for LDL oxidation. Under conditions where inhibitory protein (such as albumin) is present, LDL oxidation by Cp is optimal in the presence of superoxide, which reduces the surface copper atom of Cp. Cultured vascular endothelial and smooth muscle cells also oxidize LDL in the presence of Cp. Superoxide release by these cells is a critical factor regulating the rate of oxidation. Cultured monocytic cells, when activated by zymosan, can oxidize LDL, but these cells are unique in their secretion of Cp. Inhibitor studies using Cp-specific antibodies and antisense oligonucleotides show that Cp is a major contributor to LDL oxidation by these cells. The role of Cp in lipoprotein oxidation and atherosclerotic lesion progression in vivo has not been directly assessed and is an important area for future studies.

Infection and inflammation-induced proatherogenic changes of lipoproteins

Epidemiologic studies suggest a link between infection/inflammation and atherosclerosis. During the acute-phase response to infection and inflammation, cytokines induce tissue and plasma events that lead to changes in lipoprotein. Many of these changes are similar to those proposed to promote atherogenesis. The changes of lipoproteins during infection and inflammation are reviewed with a focus on those that are potentially proatherogenic. Hypertriglyceridemia, elevated triglyceride-rich lipoproteins, the appearance of small dense low-density lipoproteins, increased platelet-activating factor acetylhydrolase activity, and secretory phospholipase A(2), sphingolipid-enriched lipoproteins, and decreased high-density lipoprotein (HDL) cholesterol are changes that could promote atherogenesis. Moreover, alterations of proteins associated with HDL metabolism (e.g., paraoxonase, apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, hepatic lipase, phospholipid transfer protein, and serum amyloid A) could decrease the ability of HDL to protect against atherogenesis through antioxidation and reverse cholesterol transport mechanisms. These proatherogenic changes of lipoproteins may contribute to the link between infection/inflammation and atherosclerosis.

Enhanced accumulation of pericardial fluid ferritin in patients with coronary artery disease

BACKGROUND

Ferritin is a storage protein for iron that can either represent a source of iron or perform a cytoprotective action as an iron sequestrant.

OBJECTIVE

To compare the concentrations of ferritin in pericardial fluid of patients with valvular heart disease, serving as controls, and in patients with coronary artery disease.

DESIGN

We studied a total of 59 consecutive male patients undergoing elective heart valve replacement (group 1: n = 22, mean +/- SD age 55 +/- 11 years) or elective coronary artery bypass grafting (group 2: n = 37, mean +/- SD age 59 +/- 9 years).

METHODS

Iron status indicators, total protein and albumin concentrations, and lactate dehydrogenase activities were determined in pericardial fluid and serum samples obtained from patients during surgery.

RESULTS

Pericardial fluid concentrations of ferritin in both patient populations were significantly (P < 0.001) greater than the concentrations in sera: group 1, 375 (107-2030) micrograms/l compared with 146.5 (21-407) micrograms/l; group 2, 1115 (226-2500) micrograms/l compared with 152.0 (16-398) micrograms/l (median (range)), respectively. Moreover, pericardial fluid ferritin concentration was significantly (P < 0.01) greater in patients undergoing coronary artery bypass grafting than in those undergoing heart valve replacement, whereas serum ferritin concentrations did not differ between the two patient populations.

CONCLUSIONS

As pericardial fluid reflects the composition of the myocardial interstitium, we suggest that ferritin released can serve as a potential source of iron in the cardiac interstitium that may promote the generation of oxygen free radicals. Conversely, we presume that induction of ferritin synthesis, representing an important mechanism by which tissue adapts to hypoxic damage, can afford myocardial cytoprotection.

Inhibition of endothelial nitric-oxide synthase by ceruloplasmin

The plasma copper protein ceruloplasmin (CP) was found to inhibit endothelial nitric-oxide synthase activation in cultured endothelial cells, in line with previous evidence showing that the endothelium-dependent vasorelaxation of the aorta is impaired by physiological concentrations of ceruloplasmin. The data presented here indicate a direct relationship between the extent of inhibition of agonist-triggered endothelial nitric oxide synthase activation and CP-induced enrichment of the copper content of endothelial cells. Copper discharged by CP was mainly localized in the soluble fraction of cells. The subcellular distribution of the metal seems to be of relevance to the inhibitory effect of CP, because it was mimicked by copper chelates, like copper-histidine, able to selectively enrich the cytosolic fraction of cells, but not by copper salts, which preferentially located the metal to the particulate fraction.

Serum ferritin and risk of myocardial infarction in the elderly: the Rotterdam Study

BACKGROUND

Elevated body iron stores have been suggested to be a risk factor for ischemic heart disease.

OBJECTIVE

We examined whether elevated serum ferritin concentrations, other indicators of iron status, and dietary iron affected the incidence of myocardial infarction (MI) in an elderly population.

DESIGN

A nested, case-control study of 60 patients who had their first MI and 112 age- and sex-matched control subjects embedded in the population-based cohort of the Rotterdam Study.

RESULTS

The age- and sex-adjusted risk of MI for subjects with serum ferritin concentrations > or = 200 microg/L was 1.82 (95% CI: 0.90, 3.69; P = 0.096). The odds ratio (OR) was 1.26 (95% CI: 0.98, 1.64; P = 0.078) for the highest tertile of serum ferritin and was only slightly altered in a multivariate model. Risk of MI associated with the highest tertile of ferritin was most evident in current or former smokers (OR: 1.68; 95% CI: 1.17, 2.47; P for trend = 0.008) and in subjects with hypercholesterolemia (OR: 1.43; 95% CI: 0.99, 2.11; P for trend = 0.056) or diabetes (OR: 2.41; 95% CI: 1.12, 7.67; P for trend = 0.027). No association with risk of MI was observed for tertiles of serum iron, serum transferrin, or total dietary iron. For dietary heme iron, risk of MI was significantly increased in a multivariate model in which dietary energy, fat, saturated fat, and cholesterol were adjusted for (OR: 4.01; 95% CI: 1.17, 15.87; P for trend = 0.031).

CONCLUSION

In the presence of other risk factors, serum ferritin may adversely affect ischemic heart disease risk in the elderly.

Coronary heart disease and iron status: meta-analyses of prospective studies

BACKGROUND

Studies of iron status and coronary heart disease (CHD) have yielded conflicting results. In a systematic review ("meta-analysis"), we quantitatively assessed epidemiological associations reported in prospective studies.

METHODS AND RESULTS

Studies were identified by computer-assisted searches of the published literature, scanning of relevant reference lists, hand searching of relevant journals, and discussions with relevant authors. The following was abstracted: size and type of cohort, mean age, mean duration of follow-up, assay methods, degree of adjustment for confounders, and relationship of CHD risk to the baseline assay results. Twelve studies were identified, involving a total of 7800 CHD cases, with several reporting on >1 marker of iron status. For serum ferritin, with 570 CHD cases in 5 studies, comparison of individuals with baseline values >/=200 versus <200 microg/L yielded a combined risk ratio of 1.0 (95% CI, 0.8 to 1.3). For transferrin saturation, with 6194 CHD cases in 5 studies, comparison of individuals in the top third with those in the bottom third of the baseline measurements yielded a combined risk ratio of 0.9 (95% CI, 0.7 to 1.1). Comparisons of individuals in top and bottom thirds of baseline measurements also yielded nonsignificant risk ratios in combined analyses of studies involving total iron-binding capacity (combined risk ratio, 1.0; 95% CI, 0.7 to 1.5), serum iron (0.8; 95% CI, 0.7 to 1.0), and total dietary iron (0.8; 95% CI, 0.7 to 1.1).

CONCLUSIONS

Published prospective studies do not provide good evidence to support the existence of strong epidemiological associations between iron status and CHD.

The role of (E)-4-hydroxy-2-nonenal in platelet activation by low density lipoprotein and iron

(E)-4-Hydroxy-2-nonenal (HNE) is a highly reactive product of the oxidation of low density lipoprotein (LDL) which increases the platelet aggregation response to various agonists. HNE formation was increased during the enhanced platelet aggregation to thrombin, ADP. A23187 and epinephrine in the presence of LDL. The increase in platelet aggregation and HNE formation by LDL was inhibited by superoxide dismutase and catalase, suggesting superoxide and hydrogen peroxide produced by platelets during aggregation may be at least partly responsible. The responsiveness of platelets to LDL and the accompanying HNE formation was increased further in the presence of ferrous ion. The effect of ferrous ion on both platelet responses and HNE formation was decreased by superoxide dismutase, catalase and the antioxidants dipyridamole and probucol implicating platelet-derived free radicals. Ferrous ion caused an increase in the release of arachidonic acid from platelet membrane phospholipids in the presence of LDL which was probably caused by increased HNE production. The results suggest iron could increase platelet reactivity at sites of vascular injury by increasing HNE formation and promote the development of atherosclerotic lesions.

Lack of association between ferritin level and measures of LDL oxidation: the ARIC study. Atherosclerosis Risk in Communities

Body iron status has been implicated in atherosclerotic cardiovascular disease. The main hypothesis was that high iron status was associated with increased oxidation of LDL. The associations of serum ferritin (a marker of iron status) and dietary iron intake with the susceptibility of LDL to in vitro oxidation (lag phase) and autoantibodies against MDA-modified LDL (two markers of oxidation stress) were examined among 281 men and 192 women with a mean age of 59 years (S.D. = 5) who participated in the Atherosclerosis Risk in Communities (ARIC) Study visit 2 in 1990 through 1992. Lag phase duration and the autoantibodies against MDA-modified LDL were weakly correlated with each other (r = 0.19, P = 0.001 in men; r = 0.15, P = 0.03 in women). In linear regression analysis adjusting for age, field center, blood storage time, and carotid atherosclerosis case-control status, there was no association between ferritin level and the lag-phase, or between ferritin level and autoantibodies against MDA-modified LDL in either sex. Further adjustment for traditional cardiovascular risk factors (smoking, vitamin supplement use, body mass index, LDL cholesterol, hypertension and diabetes) did not alter these null results. Ferritin was significantly and positively correlated with body mass index in both sexes (r = 0.21 among men and r = 0.22 among women) and with the waist-to-hip ratio among women (r = 0.26). In addition, among women, ferritin was positively correlated with orosomucoid (r = 0.24) and with sialic acid (r = 0.19). Dietary iron was not associated with the parameters of LDL oxidation or with ferritin level. These findings do not support a role of body iron stores in promoting oxidation of LDL.

Association between body iron stores and the risk of acute myocardial infarction in men

BACKGROUND

Epidemiological evidence concerning the role of iron, a lipid peroxidation catalyst, in coronary heart disease (CHD) is inconsistent. We investigated the association of the concentration ratio of serum transferrin receptor to serum ferritin (TfR/ferritin), a state-of-the-art measurement of body iron stores, with the risk of acute myocardial infarction (AMI) in a prospective nested case-control study in men from eastern Finland.

METHODS AND RESULTS

Transferrin receptor assays were carried out for 99 men who had an AMI during an average 6.4 years of follow-up and 98 control men. Both the cases and the controls were nested from the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) cohort of 1931 men who had no clinical CHD at the baseline study. The controls were matched for age, examination year, and residence. AMIs were registered prospectively. Soluble transferrin receptors were measured by immunoenzymometric assay and ferritin concentration by radioimmunoassay from frozen baseline serum samples. The mean TfR/ferritin ratio was 15.1 (SE, 2.0) among cases and 21.3 (SE, 2.2) among controls (P=.035 for difference). In logistic regression models adjusting for other strongest risk factors for AMI and indicators of inflammation and alcohol intake, men in the lowest and second lowest thirds of the TfR/ferritin ratio had a 2.9-fold (95% CI, 1.3 to 6.6, P=.011) and 2.0-fold (0.9 to 4.2, P=.081) risk of AMI compared with men in the highest third (P=.010 for trend).

CONCLUSIONS

These data show an association between increased body iron stores and excess risk of AMI, confirming previous epidemiological findings.

Iron measures in coronary angiography patients

Excess iron has been postulated as a risk factor for coronary artery disease (CAD) because of its presence in atherosclerotic lesions, its ability to oxidize low density lipoprotein cholesterol (LDLc), and its promotion of oxygen reperfusion damage after an ischemic event. Whether iron, indirectly measured by its storage protein ferritin and its transport protein transferrin, is related to CAD was examined in a consecutive series of white male (n = 457) and female (n = 114) cardiac patients. Atherosclerosis measures were analyzed in patients grouped by tertiles of ferritin. A similar analysis was done with tertiles of transferrin. Contrary to expectations, men in the third tertile of ferritin had a smaller mean number of stenoses than men in the two lower tertiles (4.9 versus 5.6 and 5.9; P = 0.027); otherwise, there were no statistically significant differences in either number of lesions or extent of arterial narrowing based on tertiles of either measure. Separate multiple logistic regression models with age, fibrinogen, LDLc and triglycerides as covariates provided no evidence that ferritin (odds ratio = 0.88 with 95% C.I. = 0.72-1.07 for men and odds ratio = 0.79 with 95% C.I. = 0.54-1.16 for women) or transferrin (odds ratio = 0.60 with 95% C.I. = 0.31-1.16 for men and odds ratio = 1.33 with 95% C.I. 0.52-3.42 for women) were important correlates of the presence of atherosclerosis in this study.

Ceruloplasmin impairs endothelium-dependent relaxation of rabbit aorta

This study evaluated the effects of ceruloplasmin, the copper-containing blue oxidase of vertebrate plasma, on the relaxation of rabbit aortic rings after endothelial release of nitric oxide (NO). Ceruloplasmin at physiological, i.e., micromolar, concentrations inhibited relaxation of rabbit aorta induced by endothelium-dependent agonists like acetylcholine or ADP, whereas it was ineffective toward vasodilation due to direct stimulation of smooth muscle cells by nitroglycerin. The effect was reversible and specific for native, fully metalated ceruloplasmin, since relaxation was not impaired by the heat-treated or metal-depleted derivatives. A trapping mechanism, involving a direct interaction of NO or other NO-containing species (like nitrosothiols and iron-dinitrosyls) with the copper sites and/or with the free thiol of ceruloplasmin, could be safely excluded on the basis of spectroscopic and chemical analyses of the protein exposed to authentic NO, nitrosothiols, or iron-dinitrosyls. The data presented in this paper constitute the first evidence of impairment of the endothelium-dependent vasodilatation by a plasma protein and may shed some light on the still uncertain physiological role of ceruloplasmin.

Identification of the prooxidant site of human ceruloplasmin: a model for oxidative damage by copper bound to protein surfaces

Free transition metal ions oxidize lipids and lipoproteins in vitro; however, recent evidence suggests that free metal ion-independent mechanisms are more likely in vivo. We have shown previously that human ceruloplasmin (Cp), a serum protein containing seven Cu atoms, induces low density lipoprotein oxidation in vitro and that the activity depends on the presence of a single, chelatable Cu atom. We here use biochemical and molecular approaches to determine the site responsible for Cp prooxidant activity. Experiments with the His-specific reagent diethylpyrocarbonate (DEPC) showed that one or more His residues was specifically required. Quantitative [14C]DEPC binding studies indicated the importance of a single His residue because only one was exposed upon removal of the prooxidant Cu. Plasmin digestion of [14C]DEPC-treated Cp (and N-terminal sequence analysis of the fragments) showed that the critical His was in a 17-kDa region containing four His residues in the second major sequence homology domain of Cp. A full length human Cp cDNA was modified by site-directed mutagenesis to give His-to-Ala substitutions at each of the four positions and was transfected into COS-7 cells, and low density lipoprotein oxidation was measured. The prooxidant site was localized to a region containing His426 because CpH426A almost completely lacked prooxidant activity whereas the other mutants expressed normal activity. These observations support the hypothesis that Cu bound at specific sites on protein surfaces can cause oxidative damage to macromolecules in their environment. Cp may serve as a model protein for understanding mechanisms of oxidant damage by copper-containing (or -binding) proteins such as Cu, Zn superoxide dismutase, and amyloid precursor protein.

The possible role of copper ions in atherogenesis: the Blue Janus

It has been proposed that the oxidative modification of low density lipoprotein (LDL) is a key event in human atherogenesis. Copper ions can catalyse the oxidative modification of LDL in vitro and there is some evidence that they may also participate in the oxidation of LDL within the arterial wall. However, copper ions also form an intrinsic constituent of superoxide dismutase and caeruloplasmin, enzymes that may be involved in preventing oxidative injury. Atherosclerotic lesions frequently contain considerable quantities of extracellular matrix molecules. These may contribute to the expansion of the arterial neointima, causing luminal narrowing. They may also play a beneficial role by stabilising the plaque. Copper is an essential component of lysyl oxidase, an enzyme involved in the biosynthesis of collagen, which is a major constituent of the extracellular matrix. The impact of alterations in body copper status on atherogenesis is therefore difficult to predict. Experimental and epidemiological data are conflicting and therefore do not provide a clear resolution of this issue. We have reviewed the biochemical and cellular effects of copper ions that may play a role in atherogenesis.

Relationship of serum ferritin concentrations with metabolic cardiovascular risk factors in men without evidence for coronary artery disease

Elevated serum ferritin concentrations between 200 and 500 microg/l have been found to be a strong risk factor for acute myocardial infarction in Finnish men, but the reason for this association is still uncertain. In the Finnish population ferritin concentrations correlated with factors of insulin resistance syndrome. As these factors have been found to be associated with an LDL subfraction phenotype of increased concentrations of small, dense LDL particles, we hypothesized an association between ferritin and an atherogenic LDL subfraction profile, a finding which could be an explanation for the observed relationship between ferritin and atherosclerosis. Therefore we determined serum ferritin levels, metabolic cardiovascular risk factors, and the LDL subfraction phenotype in 93 healthy men without signs for infection or coronary heart disease. We found that men with moderately elevated ferritin levels (200-500 microg/l; n = 31) had a significantly worse coronary risk profile than men with lower levels ( < 200 microg/l; n = 62). Elevated ferritin concentrations were associated with significantly higher values for serum triglycerides, VLDL cholesterol, VLDL apolipoprotein B (P < 0.01), IDL cholesterol, fasting glucose (P < 0.05) and uric acid (P < 0.01), and lower levels for HDL2b and HDL2a cholesterol and apolipoprotein A-I (P < 0.05), and lipoprotein(a) (P < 0.01). Elevated ferritin levels were, however, not associated with an unfavourable LDL subfraction profile of increased concentrations of small, dense LDL particles.

Ceruloplasmin enhances smooth muscle cell- and endothelial cell-mediated low density lipoprotein oxidation by a superoxide-dependent mechanism

Cultured vascular smooth muscle cells (SMC) and endothelial cells (EC) stimulate low density lipoprotein (LDL) oxidation by free radical-mediated, transition metal-dependent mechanisms. The physiological source(s) of metal ions is not known; however, purified ceruloplasmin, a plasma protein containing 7 coppers, oxidizes LDL in vitro. We now show that ceruloplasmin also increases LDL oxidation by vascular cells. In metal ion-free medium, human ceruloplasmin increased bovine aortic SMC- and EC-mediated LDL oxidation by up to 30- and 15-fold, respectively. The maximal response was at 100-300 microg ceruloplasmin/ml, a level at or below the unevoked physiological plasma concentration. Oxidant activity was dependent on protein structure as a specific proteolytic cleavage or removal of one of the seven ceruloplasmin copper atoms inhibited activity. Three lines of evidence indicated a critical role for cellular superoxide (O2.) in ceruloplasmin-stimulated oxidation. First, the rate of production of O2. by cells correlated with their rates of LDL oxidation. Second, superoxide dismutase effectively blocked ceruloplasmin-stimulated oxidation by both cell types. Finally, O2. production by SMC quantitatively accounted for the observed rate of LDL oxidation. To show this, the course of O2. production by SMC was simulated by repeated addition of xanthine and xanthine oxidase to culture medium under cell-free conditions. Neither ceruloplasmin nor O2. alone increased LDL oxidation, but together they completely reconstituted the oxidation rate of ceruloplasmin-stimulated SMC. These results are the first to show that ceruloplasmin stimulates EC- and SMC-mediated oxidation of LDL and that cell-derived O2. accounts quantitatively for metal-dependent, free radical-initiated oxidation of LDL by these cells.

Iron and heart disease: the epidemiologic data

There has developed a general theory of chronic and degenerative disease causation--the Oxidative Stress Theory. This theory states that the production of tissue-damaging free radicals is an essential component in the pathogenesis of chronic diseases and that iron may help to catalyze the reactions producing free radicals. As a result, it has been suggested that the risk of coronary heart disease increases with increasing body iron stores. In support of that hypothesis, a prospective epidemiologic study of heart disease in Finnish men found that the risk of heart attack increased with increasing levels of serum ferritin. However, the vast majority of the epidemiologic data, including results from prospective, cross-sectional, and case-control and autopsy studies, published since that initial study have failed to support the original hypothesis that high body iron stores increase the risk of coronary heart disease.

Role of endogenous ceruloplasmin in low density lipoprotein oxidation by human U937 monocytic cells

Oxidation of lipids and lipoproteins by macrophages is an important event during atherogenesis. Activation of monocytic cells by zymosan and other agonists results in the release of multiple oxidant species and consequent oxidation of LDL. We now show evidence that ceruloplasmin, a copper-containing acute phase reactant, is secreted by zymosan-activated U937 monocytic cells, and that the protein has an important role in LDL oxidation by these cells. In one approach, ceruloplasmin has been shown to exhibit oxidant activity under the appropriate conditions. Exogenous addition of purified human ceruloplasmin stimulates U937 cell oxidation of LDL to nearly the same extent as activation by zymosan. In contrast to previous cell-free experiments (Ehrenwald, E., G.M. Chisom, and P.L. Fox. 1994. Intact human ceruloplasmin oxidatively modifies low density lipoprotein. J. Clin. Invest. 93:1493-1501.) in which ceruloplasmin by itself (in PBS) oxidizes LDL, under the conditions of the current experiments (in RPMI 1640 medium) ceruloplasmin only oxidizes LDL in the presence of cells; the mechanism by which cells overcome the inhibition by medium components has not been ascertained. As further evidence for a role of ceruloplasmin, activation of U937 cells with zymosan induces ceruloplasmin mRNA and ceruloplasmin protein synthesis after a 5-6 h lag that is consistent with that preceding LDL oxidation. Finally, neutralization by a highly specific polyclonal antibody to human ceruloplasmin inhibits LDL oxidation by at least 65%. Moreover, multiple antisense oligodeoxynucleotides targeted to different regions of the ceruloplasmin mRNA block LDL oxidation by up to 95%. The specific action of the antisense oligonucleotides has been verified by showing inhibition of ceruloplasmin synthesis and by the ability of exogenous ceruloplasmin to overcome the inhibition. In summary, these results are consistent with a mechanism in which cell-derived ceruloplasmin participates in oxidation of LDL by U937 monocytic cells. The data also show that cellular factors in addition to ceruloplasmin, possibly active oxygen species and/or lipoxygenases, are essential and act synergistically with ceruloplasmin to oxidize LDL.

Structure, oxidant activity, and cardiovascular mechanisms of human ceruloplasmin

Ceruloplasmin is the principal carrier of copper in human plasma. It is an abundant protein that participates in the acute phase reaction to stress, but its physiological function(s) is unknown. An antioxidant activity of ceruloplasmin has been described, but recent evidence suggests that the protein may also exhibit potent pro-oxidant activity and cause oxidative modification of low density lipoprotein (LDL). The pro-oxidant activity is highly dependent on the structure of the protein; removal of a single one of the seven integral copper atoms, or a specific proteolytic cleavage event, completely suppresses LDL oxidation. This newly described pro-oxidant activity may help to explain epidemiological studies indicating that ceruloplasmin is an independent risk factor for cardiovascular disease.