The iron hypothesis:does iron play a role in atherosclerosis?

Variables associated with subclinical atherosclerosis among rheumatoid arthritis patients of Gulf Cooperative Council countries

OBJECTIVES

To evaluate the cardiovascular disease (CVD) as demonstrated by carotid intima-media thickness (cIMT) and the cluster risk factors of CVD including traditional and non-traditional, urinary functions, iron buildup, and hemorheology in rheumatoid arthritis (RA) patients of Gulf Cooperative Council (GCC) countries.

METHODS

Carotid intima-media thickness was obtained from 216 RA patients, free of atherosclerotic diseases. The correlation between cIMT and the possible CVD risk factors was carried out using regression analysis. Results: The mean cIMT was observed as 0.58±0.11 mm. Mean age was 48±13 years. Univariate analysis revealed a positive association (p less than 0.05) between cIMT and age, body mass index, systolic blood pressure (SBp), and diastolic blood pressure, c-reactive protein (CRP), triglycerides (TG), low-density lipoprotein (LDL), erythrocyte sedimentation rate (ESR), hemoglobin (Hb), hematocrit (Hct), mean cell volume, platelet, monocytes, eosinophils, ferritin, creatinine, and uric acid. Negative relationship was observed between cIMT and glomerular filtration rate (GFR), transferrin, and high-density lipoprotein. Multiple linear regression analysis exhibited a positive association between cIMT and the age, LDL, eosinophil, SBp, and the ESR, whereas, negative connection with the GFR and transferrin. Conclusion: In this study, we found that the eosinophils, and low transferrin, are the potential candidates for the CVD risk factors in RA patients. Fasting blood glucose level was also observed to be a significant risk factor in diabetic as well as non-diabetic RA. The remaining CVD risk factors in RA patients of GCC countries including older age, high SBp, ESR, LDL, and low GFR were similar to the international population.

Serum high-sensitive C-reactive protein is associated with dietary intakes in diabetic patients with and without hypertension: a cross-sectional study

Background Serum high-sensitive C-reactive protein (hs-CRP) concentrations independently predict the development of diabetes, metabolic syndrome and cardiovascular disease. However, the impact of dietary factors on serum high-sensitive C-reactive protein concentrations in diabetic patients has received limited attention. We aimed to investigate the association between dietary factors and high-sensitive C-reactive protein , among diabetic patients with and without hypertension and healthy subjects. Methods In this cross-sectional study, diabetics with ( n = 325) and without hypertension ( n = 599) and healthy individuals ( n = 1220) were recruited in Mashhad, Iran. Dietary intake was assessed by 24-h recall. Biochemical parameters including serum high-sensitive C-reactive protein were measured using standard protocols. Stepwise multiple regression analysis was used to predict whether serum high-sensitive C-reactive protein concentration was associated with dietary constituents. Results High-sensitive C-reactive protein was significantly higher among hypertensive and non-hypertensive diabetic patients compared with healthy subjects ( P < 0.001). The dietary intake of zinc + 6.4% and calcium -3.4% and body mass index +3.9% explained approximately 13.7% of the variation in serum high-sensitive C-reactive protein among diabetic hypertensive patients. Approximately 9.7% of the variation in serum high-sensitive C-reactive protein in diabetic non-hypertensive patients could be explained by body mass index, and intake of sodium, iron and cholesterol. In the healthy subjects, approximately 4.4% of the total variation in serum high-sensitive C-reactive protein concentration could be explained by cholesterol consumption and waist circumference. Conclusion Serum high-sensitive C-reactive protein concentrations were found to be a significant predictor for hypertensive and non-hypertensive diabetic subjects. There was a significant association between dietary factors include zinc, iron, sodium and cholesterol and serum high-sensitive C-reactive protein, while there was an inverse association between dietary calcium and serum high-sensitive C-reactive protein in diabetic hypertensive individuals.

Iron and peripheral arterial disease: revisiting the iron hypothesis in a different light

The relationship between iron status and atherosclerosis has long been a topic of debate in the literature. Despite more than 25 years of research, there is no consensus regarding a causal relationship. To date, the vast majority of studies have focused on iron burden with respect to a hypothesized role in the onset and progression of coronary artery disease. However, the effect of iron in the coronary arterial system may differ mechanistically and therefore clinically from its effect in the peripheral arterial system. This review will summarize the biochemical, pathologic, animal, and clinical research data with respect to iron and atherosclerosis. This background will be expanded upon to provide insights into ongoing studies and paths for future investigations into the role of iron and peripheral arterial disease.

Regular blood donation improves endothelial function in adult males

OBJECTIVE

Endothelial dysfunction, secondary to systemic inflammation and oxidative stress, is known to play a major role in the development and progression of atherosclerosis. It is hypothesized that the lower incidence of coronary artery disease in the premenopausal period in females when compared with males is associated with regular menstrual blood loss. We investigated whether regular blood donation (BD) is associated with improved endothelial function in healthy adult males.

METHODS

Fifty young healthy male volunteers volunteers with a mean age of 30 ± 6 years without overt cardiovascular disease were enrolled to participate in serial consecutive BDs. Serum iron levels as oxidative stress parameters, flow-mediated dilatation (FMD) for endothelial function, 24-h mean diastolic blood pressure for peripheral vascular resistance identification, and high-sensitivity C-reactive protein (hs-CRP) levels as systemic inflammatory markers were evaluated before and after BD. This study used a prospective observational cohort design. Patients with cardiovascular and inflammatory diseases were excluded.

RESULTS

BD was found to improve FMD steadily and significantly when compared with the baseline (mean ± SD: 9.9% ± 3.8%, 10.44% ± 3.9%, 10.65% ± 3.9%, and 10.75 ± 3.9%, respectively, p=0.15, p=0.02, p=0.006 as compared with the baseline). A steady decrease was identified in hs-CRP levels after serial BDs, although this decrease was not statistically significant in the all phases (2.96 ± 3.3 mg/L, 2.26 ± 1.5 mg/L, and 2.12 ± 1.5 mg/L, respectively, p=0.829, p=0.558). The 24-h mean diastolic blood pressures were significantly lower in the chronic phase (77 ± 9 mm Hg, 75 ± 7 mm Hg, and 72 ± 8 mm Hg, respectively, p=0.50, p=0.003), whereas there was no significant change in iron levels in the acute and chronic phases (66 ± 32 mg/dL, 72 ± 43 mg/dL, and 68 ± 33 mg/dL, respectively, p=1.000, p=1.000).

CONCLUSION

The results of the study indicate that regular BD improves endothelial function.

Dietary iron intake and body iron stores are associated with risk of coronary heart disease in a meta-analysis of prospective cohort studies

The link between iron intake as well as body iron stores and coronary heart disease (CHD) has been contentiously debated, and the epidemiologic evidence is inconsistent. We aimed to quantitatively summarize the literature on the association between dietary iron intake/body iron stores and CHD risk by conducting a meta-analysis of prospective cohort studies. PubMed was used to find studies published through June 2013 in peer-reviewed journals. Embase or a hand search of relevant articles was used to obtain additional articles. The pooled RRs of CHD incidence and mortality with 95% CIs were calculated by using either a random-effects or fixed-effects model, as appropriate. Twenty-one eligible studies (32 cohorts) including 292,454 participants with an average of 10.2 y of follow-up were included. Heme iron was found to be positively associated with CHD incidence (RR: 1.57; 95% CI: 1.28, 1.94), whereas total iron was inversely associated (RR: 0.85; 95% CI: 0.73, 0.999). Neither heme-iron nor total iron intakes were significantly associated with CHD mortality. Both transferrin saturation and serum iron were inversely related to CHD incidence [RR (95% CI): 0.76 (0.66, 0.88) and 0.68 (0.56, 0.82), respectively], but only transferrin saturation was inversely associated with CHD mortality (RR: 0.85; 95% CI: 0.73, 0.99). In conclusion, total iron intake and serum iron concentrations were inversely associated with CHD incidence, but heme iron intake was positively related to CHD incidence. Elevated serum transferrin saturation concentration was inversely associated with both CHD incidence and mortality. Future research is needed to establish the causal relation and to elucidate potential mechanisms.

Non transferrin bound iron: nature, manifestations and analytical approaches for estimation

Iron is an essential trace element and plays a number of vital roles in biological system. It also leads the chains of pathological actions if present in excess and/or present in free form. Major portion of iron in circulation is associated with transferrin, a classical iron transporter, which prevent the existence of free iron. The fraction of iron which is free of transferrin is known as "non transferrin bound iron". Along with the incidence in iron over loaded patient non transferrin bound iron has been indicated in patients without iron overload. It has been suggested as cause as well as consequence in a number of pathological conditions. The major organs influenced by iron toxicity are heart, pancreas, kidney, organs involved in hematopoiesis etc. The most commonly suggested way for iron mediated pathogenesis is through increased oxidative stress and their secondary effects. Generation of free oxygen radicals by iron has been well documented in Fenton chemistry and Haber-Weiss reaction. Non transferrin bound iron has obvious chance to generate the free reactive radicals as it is not been shielded by the protective carrier protein apo transferrin. The nature of non transferrin bound iron is not clear at present time but it is definitely a group of heterogenous iron forms free from transferrin and ferritin. A variety of analytical approaches like colorimetry, chromatography, fluorimetry etc. have been experimented in different research laboratories for estimation of non transferrin bound iron. However the universally accepted gold standard method which can be operated in pathological laboratories is still to be developed.

Iron Balance in Regular Blood Donors

SUMMARY: BACKGROUND: Numerous reports have shown that iron stores decrease in blood donors after donation. As we need healthy donors, it is essential to test hemoglobin and ferritin levels for preventing reduced of iron stores in donors. METHODS: This study was conducted on 235 healthy men. The donors were divided into three groups: group I) control group with no donation; group II)  case group 1 with two donations within 1 year; group III)  case group 2 with three donations within 1 year. RESULTS: The mean level of hemoglobin was 15.9 and 14.7 g/dl in the control group and in the case group, respectively (p < 0.0000). The mean level of serum ferritin in group I, II and III, was 108, 56 and 26 μg/l, respectively (p < 0.0000). When studying various stages of iron deficiency in donors, it could be shown that 58% of group III donors but only 1% of control group donors had a negative iron balance. Moreover, iron deficiency anemia was observed in 20% of group III donors. CONCLUSION: Just measuring the hemoglobin level is not sufficient for selecting donors. In addition, testing of the ferritin level and iron supplementation are recommended in regular donors with more than one donation per year.

HFE C282Y Homozygosity Is Associated With Lower Total and Low-Density Lipoprotein Cholesterol

Background— Previous studies have suggested a positive association of coronary heart disease risk and both serum ferritin concentrations and C282Y heterozygosity. Relationships between serum lipids, C282Y homozygosity, and serum ferritin have not been well established.

Methods and Results— The Hemochromatosis and Iron Overload Screening study screened 101 168 participants in primary care from 5 field centers in the United States and Canada with serum ferritin, transferrin saturation, and HFE genotyping for C282Y and H63D mutations. Serum lipids were measured in a subset of 176 C282Y homozygotes (63 male, 113 female whites) without a prior diagnosis of, family history, or treatment for hemochromatosis and a matched sample of participants with normal transferrin saturation and serum ferritin without C282Y or H63D mutations (wild-type, 123 male, 189 female whites). The proportion of subjects who reported using prescription cholesterol-lowering medications was ≈3 times higher in HFE wild-type subjects than C282Y homozygotes among men (22% versus 7%; P =0.02) and, in women, 2 times higher (16% versus 8%; P =0.07). After excluding subjects taking cholesterol medications, C282Y homozygotes had significantly lower mean total and low-density lipoprotein cholesterol concentrations than wild-type subjects, with larger genotypic differences for low-density lipoprotein in men (−0.62 mmol/L; 95% CI, −0.93 to −0.33) than in women (−0.28 mmol/L; 95%, CI −0.52 to −0.08).

Conclusions— Total mean serum cholesterol and low-density lipoprotein levels were lower in C282Y homozygotes than in HFE wild-type participants. Further studies are required to determine whether this is related to iron overload, HFE alleles, or other factors on C282Y-positive chromosome 6p haplotypes.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Influence of iron chelators on myocardial iron and cardiac function in transfusion-dependent thalassaemia: a systematic review and meta-analysis

Iron chelators have dramatically prolonged the life expectancy of patients with transfusion-dependent thalassaemia, but their precise clinical benefit in reducing the myocardial iron burden and improving cardiac function is unknown. This systematic review and meta-analysis included published clinical trials that assessed the efficacy of iron chelators in regularly transfused patients of thalassaemia major for two commonly reported outcomes - myocardial iron content and left ventricular ejection fraction (LVEF). The meta-analysis of 392 patients for myocardial iron content and 291 patients for LVEF showed that (i) iron chelators reduced cardiac iron content by 23.9% (95% confidence interval 17.3-29.8%); (ii) there was no significant difference between the amount of iron reduced by deferoxamine and deferiprone (P = 0.9504); and (iii) LVEF was not significantly influenced by iron chelators - summary Hedge's g 0.13 (95% confidence interval -0.10-0.36). A significant publication bias existed for LVEF (Egger's P = 0.049) but not for myocardial iron (Egger's P = 0.871). Our results indicate that iron chelators significantly reduce myocardial iron content. Further, the choice of deferoxamine versus deferiprone may rest on factors other than their efficacy to reduce cardiac iron load.

Iron and thrombosis

Although essential for cell physiology, an increase or depletion of body iron has harmful effects on health. Apart from iron deficiency anemia and iron overload-related organ tissue damage, there are increasing evidences that body iron status is implicated in atherosclerotic cardiovascular diseases. The hypothesis formulated in 1981 that iron depletion may protect against cardiovascular events is intriguing and has generated a significant debate in the last two decades. Indeed, to study this phenomenon, several investigators have tried to design appropriate experimental and clinical studies and to identify useful biochemical and genetic markers of iron status. The results of the literature on the effect of iron deficiency and overload on vascular health are critically reviewed in this study from a pathogenic and clinical point of view.

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.

Brain microvascular and intracranial artery resistance to atherosclerosis is associated with heme oxygenase and ferritin in Japanese quail

Oxidative stress and increased oxidation of low-density lipoprotein (oxLDL) through free radical-mediated tissue injury may be important factors in the development of extracranial atherosclerotic lesions. However, the roles of oxidative stress and hypercholesterolemia in intracranial atherosclerosis is less established. The induction of heme oxygenase (HO) is a cellular response to oxidative stress, and inducible HO (HO-1) may protect against oxidized lipids such as those produced by oxidative stress. We investigated the effects of oxLDL on cell and tissue viability, HO-1 and ferritin expression in extracranial and intracranial endothelial cells, and the arteries of cholesterol-induced atherosclerosis (CIA) Japanese quail. We report that cultured microvascular endothelial cells from the brain (QBMEC) and carotid (QCEC) differ in their response to oxidative stress. The QCECs are less responsive than QBMECs to oxidative stress induced by oxLDL, as evident by lower expression of HO-1 mRNA, HO activity, and ferritin levels. Furthermore, the higher levels of catalytic iron, thiobarbituric acid reactive substances, and lactate dehydrogenase released in QCECs indicated that these cells are more susceptible to oxidative stress than QBMECs. We also investigated the relationship between extent of atherosclerotic plaque deposition and the extracranial and intracranial arterial expression of HO-1 in quail. The common carotid and vertebral (extracranial) arteries had higher tissue cholesterol levels (starting at 2 weeks of cholesterol-supplementation) and a greater atherosclerotic plaque score (starting at 4 weeks of cholesterol-supplementation) compared with middle cerebral and basilar (intracranial) arteries, and this may be relevant to the effect of aging on the process of atherogenesis. The extracranial arteries also had early and greater levels of lipid peroxidation and catalytic iron coupled with lower expression of HO-1 protein, HO activity, and ferritin compared to the intracranial vessels. These observations suggest that the extracranial and intracranial arterial walls respond differently to oxidation of lipoproteins, and support the feasibility of increased HO-1 expression as a means of protection against oxidant injury.

Iron sucrose augments homocysteine-induced endothelial dysfunction in normal subjects

Intravenous iron is commonly used in conjunction with erythropoietic agents to treat anemia in patients with chronic kidney disease. Iron has been proposed to promote oxidative stress and endothelial dysfunction in vascular tissues. We studied the acute effects of intravenous iron sucrose on homocysteine-induced endothelial dysfunction in the brachial artery of normal human subjects. In all, 40 healthy subjects received intravenous iron sucrose 100 mg or placebo over 30 min immediately before ingestion of 100 mg/kg of oral methionine in a double-blind, randomized study. Flow- and nitroglycerin-mediated dilation in the brachial artery, serum markers of iron stores, and homocysteine and nitrotyrosine levels were measured before and after study drug administration. Intravenous iron significantly increased transferrin saturation and non-transferrin-bound iron (NTBI) when compared with placebo. Flow-mediated dilation significantly decreased from baseline 1 h after administration of iron sucrose when compared with placebo (from 6.66+/-0.47 to 1.93+/-0.35% after iron sucrose vs from 6.00+/-0.40 to 5.61+/-0.46% after placebo, P<0.001), but did not differ between groups at 4 h (1.10+/-0.39 vs 1.33+/-0.51%). Nitroglycerin-mediated vasodilation, and homocysteine and 3-nitrotyrosine levels did not differ after administration of iron sucrose and placebo. Intravenous administration of iron sucrose in the setting of transient hyperhomocysteinemia induced by methionine ingestion significantly increased transferrin saturation and plasma levels of NTBI and significantly attenuated flow-mediated dilation in the brachial artery when compared with placebo. This potential mechanistic link between intravenous iron and endothelial dysfunction warrants further study of cardiovascular effects of intravenous iron in anemic chronic kidney disease populations.

Intravenous iron therapy as a possible risk factor for atherosclerosis in end-stage renal disease

Atherosclerosis is a disease of the arterial wall, with increasing wall thickness representing an early event in the progression of the disease. It has been suggested that iron overload, as assessed by increased serum ferritin concentration, may be a risk factor for atherosclerosis. The aim of this study was to investigate the relationship between the influence of intravenous (IV) iron therapy and ferritin levels and carotid intima media thickness (C-IMT) in dialysis patients. Sixty patients (51 +/- 14) years were divided into two groups according to their IMT obtained by ultrasound; group I (high risk) and group II (low risk). The parameters assessed were serum creatinine, urea, calcium, phosphorus, hemoglobin, albumin, uric acid, iron, ferritin, and lipid levels. Thirty-eight patients (88%) in group I and 5 patients (12%) in group II received IV iron therapy while 5 patients (29%) in group I and 12 patients (71%) in group II (P < 0.001) did not receive IV iron therapy. Ferritin levels were higher in group I than in group II (581 +/- 303 and 306 +/- 224) (P < 0.001). C-IMT measurements correlated with serum ferritin and with the intravenous iron dose received during the 24 months preceding the study (r = 0.315, P = 0.015; r = 0.471, P = 0.001). The findings indicate that IV iron therapy and elevated serum ferritin levels may cause an increase in the incidence of atherosclerosis.

Iron stores and vascular function in voluntary blood donors

BACKGROUND

Iron is a pro-oxidant cofactor that may be linked to atherosclerosis progression. Reduction of body iron stores secondary to blood donation has been hypothesized to reduce coronary risk, but retrospective studies have yielded inconsistent findings. We sought to assess the effects of blood donation frequency on body iron stores and physiological and biochemical biomarkers of vascular function associated with atherosclerosis progression.

METHODS AND RESULTS

Forty high-frequency voluntary blood donors (> or =8 donations in past 2 years) and 42 low-frequency blood donors (1 to 2 donations in past 2 years) aged 50 to 75 years were randomly selected from American Red Cross of Connecticut blood donor records. Flow-mediated dilation in the brachial artery, serum markers of iron stores, vascular inflammation and oxidative stress, and cardiac risk factors were assessed in all subjects. Serum ferritin was significantly decreased in high-frequency blood donors when compared with low-frequency blood donors (median values 17 versus 52 ng/mL; P<0.001), but hematocrit did not differ between groups. Flow-mediated dilation in the brachial artery was significantly greater in high-frequency donors when compared with low-frequency donors in univariate analysis (5.5+/-2.6% versus 3.8+/-1.6%; P=0.0003) and in multivariate analysis adjusting for cardiac risk factors and other potential confounders. Serum biomarkers of vascular inflammation did not differ between groups but 3-nitrotyrosine, a marker of oxidative stress, was decreased in high-frequency donors when compared with low-frequency donors.

CONCLUSIONS

High-frequency blood donors had evidence of decreased body iron stores, decreased oxidative stress, and enhanced vascular function when compared with low-frequency donors. These findings support a potential link between blood donation and reduced cardiovascular risk that warrants further investigation in prospective outcome studies.

Effects of oxidant-induced injury on heme oxygenase and glutathione in cultured aortic endothelial cells from atherosclerosis-susceptible and -resistant Japanese quail

Recent studies on cultured aortic endothelial cells (AECs) from atherosclerosis-susceptible (SUS) and -resistant (RES) strains of Japanese quail suggest that differences in atherosclerosis susceptibility between RES and SUS may be due to differences in endothelial heme oxygenase (HO) and antioxidant components. We have now investigated the effects of oxidant-induced injury on HO and glutathione (GSH) in AECs from SUS and RES quail. We report that cultured AECs from SUS and RES birds differ in their response to oxidative stress. AECs from the SUS strain cells are more susceptible than those from the RES strain to oxidative stress induced by tert-butylhydroperoxide, as judged by lower HO activity, HO-1 expression, ferritin and GSH levels. Aortic endothelial cells from SUS birds also showed higher levels of catalytic iron, TBARS production and LDH release compared with RES cells, indicating that SUS AECs are more susceptible to oxidative stress than cells from the resistant strain. Furthermore, independently of genetic status, AECs from old birds have higher TBARS and lower levels of HSP70 induction than AECs from younger birds, suggesting that aging is associated with a decreased ability of AECs to respond to oxidative stress, and this may be relevant to the permissive effect of aging on the process of atherogenesis. Our results indicate that genetic factors and endogenous antioxidant systems in the blood vessel wall may be important in determining the susceptibility of vascular cells to oxidative stress and atherosclerotic plaque formation.

Iron supplementation does not affect the susceptibility of LDL to oxidative modification in women with low iron status

Elevated iron stores may or may not promote atherogenesis by increasing free radical formation and oxidative stress, but controlled diet and supplement trials are lacking. We tested the hypothesis that iron supplementation does not increase the susceptibility of LDL to undergo oxidative modification in women with low iron status. A randomized, double-blind, 2-period crossover study design (n=26) was used to examine the effects of the following diets on measures of LDL oxidation: average American diet (AAD) [36% of energy as fat; 15% saturated fatty acids (SFA)], and a Step 2 diet (26% fat; 7% SFA). In addition, subjects received either a supplement containing 160 mg of ferrous sulfate (50 mg elemental iron) or a placebo twice daily [supplement group received a total of 320 mg ferrous sulfate (100 mg elemental iron) daily]. After supplementation, serum ferritin differed between the supplement and placebo groups (P=0.008). Measures of LDL oxidation were not affected by supplement intake; however, they were affected by diet. Lag time was shorter after the women consumed the AAD diet than after the Step 2 diet (P<0.0001). The diets did not affect the rate of oxidation or total dienes. Although iron status was improved by aggressive iron supplementation, LDL oxidative susceptibility was not affected. As expected, lag time was increased after the women consumed the low fat, low SFA diet. Therefore, the results of this study do not support a relationship between iron status and LDL oxidation.

A historical cohort study of the effect of lowering body iron through blood donation on incident cardiac events

BACKGROUND

Low body iron may protect against atherosclerotic cardiovascular disease through limiting oxidation of low-density lipoprotein cholesterol. Observational studies suggest that donation of whole blood might be associated with reduced risk of cardiovascular events.

STUDY DESIGN AND METHODS

In this retrospective cohort study, a total of 1508 adults who donated more than 1 unit of whole blood each year between 1988 and 1990 (frequent donors) and 1508 age- and sex-matched adults who donated only a single unit in that 3-year period (casual donors) were studied. A standardized questionnaire ascertained participant characteristics and occurrence of incident acute myocardial infarction, coronary angioplasty, coronary bypass surgery, and deaths between 1990 and 2000. Hospital records confirmed events. Cause of death was determined from death certificates.

RESULTS

A total of 643 subjects were lost, 113 declined, 156 were deceased but were included in the analysis, and 2104 were surveyed a median of 10 years after the index donation. Frequent donors weighed less and were less likely to be currently taking antihypertensive and lipid-modifying drugs. Events occurred in 6.3 percent of frequent and 10.5 percent of casual donors. After adjustment for group differences, the OR was D.60 (85% CIs 0.43, 0.83; p < 0.001). Events were less frequent in female donors than in male donors and less frequent in subjects who had donated before 1988 than in those who had not donated before 1988.

CONCLUSION

Frequent and long-term whole blood donation is associated with a lower risk of cardiovascular events.

Target hemoglobin in patients with renal failure

15 years after recombinant erythropoietin (EPO) has become available for the treatment of renal anemia, the target hemoglobin concentration to be achieved is still controversial. A positive impact of partial correction of renal anemia on quality of life has been conclusively demonstrated. Several more recent studies indicate that further improvement of well-being can be achieved with normalization of hemoglobin levels. In addition, there is increasing evidence that anemia is associated with the progression of left-ventricular hypertrophy and mortality. These findings imply that correction of renal anemia has the potential to improve patient prognosis. However, in patients with advanced cardiac disease, the US normal hematocrit failed to demonstrate a prognostic benefit and instead suggested that the attempt to normalize hemoglobin may be harmful. Nevertheless, in patients with less advanced cardiac disease complete correction of renal anemia may prevent progressive ventricular dilatation. The impact of early anemia correction is currently tested in several trials in predialysis patients. Irrespective of the uncertainties about the upper target range, current US and European guidelines have defined a hemoglobin concentration of 11 g/dl as the lower target range on the basis of both symptomatic and prognostic considerations. In the majority of patients these minimum requirements are not yet achieved. Less then 10% of patients receive EPO prior to the onset of dialysis, the mean hemoglobin level at the start of dialysis is not higher than 9 g/dl and a significant proportion of patients permanently remain below 11 g/dl.

MCV as a guide to phlebotomy therapy for hemochromatosis

BACKGROUND

A multitude of recommendations exist for laboratory assays to monitor the pace and endpoints of phlebotomy therapy for hemochromatosis. All of these recommendations rely on an assessment of storage iron to guide treatment, and none have been prospectively evaluated.

STUDY DESIGN AND METHODS

Nine consecutive patients underwent serial monitoring of Hb, MCV, transferrin saturation, and ferritin during weekly phlebotomy to deplete iron stores (induction therapy) and less frequent sessions to prevent iron reaccumulation (maintenance therapy). Changes in MCV and Hb were used to guide the pace of phlebotomy over a median of 7 years of follow-up.

RESULTS

During induction therapy, the MCV increased transiently because of reticulocytosis and then stabilized for a prolonged period before decreasing more sharply, which reflected iron-limited erythropoiesis. Iron depletion was achieved after a median of 38 phlebotomies and removal of 9.0 g of iron. Maintenance phlebotomy was targeted to maintain the MCV at 5 to 10 percent below prephlebotomy values and the Hb at >13 g per dL. Transferrin saturation fluctuated considerably during treatment, but remained below 35 percent during MCV-guided maintenance therapy. Ferritin values were not useful guides to the pace of phlebotomy. The median maintenance therapy phlebotomy interval was 7.5 weeks (range, 6-16), which corresponded to an average daily iron removal of 35 to 67 microg per kg. Most patients showed evidence of iron reaccumulation at phlebotomy intervals of 8 weeks or more.

CONCLUSION

The MCV is an inexpensive, precise, physiologic indicator of erythropoietic iron availability. When used in conjunction with the Hb, it is a clinically useful guide to the pace of phlebotomy therapy for hemochromatosis.