Comparison of the serum ferritin and percentage of transferrin saturation as exposure markers of iron-driven oxidative stress-related disease outcomes

Inverted U-Shaped Association of Soluble Transferrin Receptor Concentrations with Risks of Cardiovascular Diseases in Overweight Individuals: A Cross-Sectional Study

Background

Iron metabolism may play a role in cardiovascular disease (CVD) pathogenesis. The association between iron metabolism and CVD has yet to be fully investigated. This study evaluated whether iron metabolism was associated with CVD risk and whether the body mass index (BMI) of US adults varied the association.

Methods

A cross-sectional study was performed using the National Health and Nutrition Examination Survey (NHANES), conducted from 2017 to 2018. Generalized additive models (GAMs) and multivariable logistic regression were adopted to analyze the association between iron metabolism (serum iron (SI), serum ferritin (SF), transferrin saturation (TSAT), and soluble transferrin receptor (sTfR)) and CVD risk. Further, stratified analysis was conducted to identify patients with high CVD risk.

Results

Participants with CVD tended to have significantly increased levels of sTfR (p < 0.001) and decreased levels of TSAT (p < 0.001) and SI (p < 0.001). After adjusting for confounding factors, sTfR levels had a significant positive association with CVD risk (Q1 as reference, Q4 odds ratio (OR) 2.1, 95% CI 1.54-2.87, p < 0.001). Notably, the association between sTfR and CVD risk differed in the BMI subgroup (p for interaction < 0.05). We identified an inverted U-shaped relationship between sTfR and the CVD risk in the group of overweight individuals (non-linear p < 0.001). When the sTfR level was below the turning point (sTfR = 5.35 mg/L), a per unit increase in the sTfR level was correlated with a 78% greater adjusted OR of CVD risk (OR, 1.78 [1.44, 2.19]).

Conclusions

Increased sTfR levels were non-linearly related to the CVD risk in the overweight population.

Meat consumption and the risk of hip fracture in women and men: two prospective Swedish cohort studies

PURPOSE

To study the association between meat intake (predominantly red and processed meats) and the risk of hip fracture, as well as the association between meat intake and biomarkers of inflammation, oxidative stress, bone turnover, body composition, and bone mineral density (BMD).

METHODS

Data from the Swedish Mammography Cohort and the Cohort of Swedish men (n = 83,603, 54% men) with repeated investigations and their respective clinical sub-cohorts was utilised. Incident hip fractures were ascertained through individual linkage to registers. Associations were investigated using multivariable Cox and linear regression analyses.

RESULTS

During up to 23 years of follow-up (mean 18.2 years) and 1,538,627 person-years at risk, 7345 participants (2840 men) experienced a hip fracture. Each daily serving of meat intake conferred a hazard ratio (HR) of 1.03 (95% confidence interval [CI] 1.00; 1.06) for hip fracture. In quintile 5, compared to quintile 2, the HR was 1.11 (95% CI 1.01; 1.21) among all participants. In the sub-cohorts, meat intake was directly associated with circulating levels of interleukin-6, C-reactive protein, leptin, ferritin, parathyroid hormone, and calcium.

CONCLUSION

A modest linear association was found between a higher meat intake and the risk of hip fractures. Our results from the sub-cohorts further suggest that possible mechanisms linking meat intake and hip fracture risk may be related to the regulation of bone turnover, subclinical inflammation, and oxidative stress. Although estimates are modest, limiting red and processed meat intake in a healthy diet is advisable to prevent hip fractures.

Iron Metabolic Biomarkers and the Mortality Risk in the General Population: A Nationwide Population-Based Cohort Study

Context

Iron is an essential element in the human body and plays a critical role in many physiological and cellular processes. However, the association between iron status and the risk of all-cause or cause-specific mortality has not been well-investigated. And it is unclear whether the association between iron metabolic biomarkers and the risk of mortality differs between people with and without diabetes mellitus (DM).

Objective

This work aimed to investigate associations between iron metabolic biomarkers and all-cause and cause-specific mortality risk in the general population, and heterogeneities in the associations among population with and without DM..

Methods

A total of 29 166 adults from the National Health and Nutrition Examination Survey (NHANES) III and NHANES 1999 to 2010 were included, with linkage to the National Death Index to December 31, 2019. Cox proportional-hazard models and Fine-Gray subdistribution hazard models were used to estimate associations between iron metabolic biomarkers and outcomes.

Results

During a median follow-up of 18.83 years, 9378 deaths were observed, including 3420 cardiovascular disease (CVD) deaths and 1969 cancer deaths. A significant linear association between serum ferritin (SF) and all-cause mortality was observed among the overall population and those without DM. J-shaped associations between transferrin saturation (TSAT) and all-cause and CVD mortality were observed among all populations. In the overall population, compared to the first quartile (Q1) group, the adjusted hazard ratio (HR) (95% CI) for all-cause mortality was 1.07 (1.00-1.15), 1.05 (0.98-1.12), 1.13 (1.05-1.21) in Q2, Q3, and Q4 groups for SF, while the HR was 0.94 (0.88-0.99), 0.92 (0.86-0.97), and 0.93 (0.88-0.99) for TSAT. In individuals without DM, the adjusted HR of the Q4 of SF were 1.19 (1.03-1.37) for CVD mortality and 1.25 (1.05-1.48) for cancer mortality. In individuals with DM, the adjusted HRs of the Q4 of TSAT were 0.76 (0.62-0.93) for CVD mortality and 1.47 (1.07-2.03) for cancer mortality.

Conclusion

Iron metabolism abnormalities increase mortality risk in the general population. The associations of iron status with mortality were significantly different between individuals with and without DM, which indicated tailored strategies for iron homeostasis are needed.

Ferritin and iron supplements in gestational diabetes mellitus: less or more?

Iron metabolism has been found to be closely related to gestational diabetes mellitus (GDM). Excessive ferritin levels were shown to be related to an increased risk of GDM because of iron overload which may lead to insulin resistance and β-cell injury by enhancing oxidative stress and inflammatory responses. On the contrary, insufficient ferritin levels can cause a number of obstetric complications, such as high incidence rates of anaemia and gestational hypertension. Therefore, high or low ferritin levels may have adverse effects on the mother and the foetus, putting clinicians in a dilemma when giving pregnant women iron supplements. This also explains why there have been more conflicting findings in the studies on dietary or oral iron supplementation during pregnancy. Hence, there is an urgent need for more evidence and strategies for appropriate recommendations for ferritin levels and iron supplementation during pregnancy to prevent iron insufficiency without causing iron overload and increasing the risk of GDM. Therefore, we gave an updated review on the association of GDM with ferritin metabolism, ferritin levels and iron supplementation based on the summary of the latest research.

Evaluation of serum iron status indicators in patients with primary open angle glaucoma

PURPOSE

To investigate the relationship between serum iron status indicators (ferritin) levels and POAG.

METHODS

The files of all glaucoma patients who applied to the ophthalmology clinic between January 2018 and January 2022 were reviewed retrospectively. Laboratory data from fasting blood tests, internal medicine outpatient clinic reports, and extensive ophthalmologic examination data, including fundus photographs showing the optic disc, were collected from the files. A control group was formed from individuals with adequate general and eye health, age- and gender-matched individuals who had undergone examination in the ophthalmology clinic within the same date range. Serum iron status indicators and some laboratory data of POAG patients and healthy controls were compared.

RESULT

Of our participants, consisting of 65 patients with POAG and 72 healthy controls, 84 (61.32%) were female and 53 (38.68%) were male. It was observed that serum ferritin level was significantly higher in POAG patients compared to healthy controls, and the total iron binding capacity was significantly lower (respectively (p = 0.022), (p = 0.002). In logistic regression analysis, it was found that the risk of POAG increased in cases with high serum ferritin levels (OR = 0.982; p = 0.012). In addition, the risk of POAG was found to increase in cases where MCV was lower (OR = 1.121; p = 0.039).

CONCLUSION

This study shows that higher serum ferritin levels are associated with a higher risk of POAG.

Oxidative Stress in Optic Neuropathies

Increasing evidence indicates that changes in the redox system may contribute to the pathogenesis of multiple optic neuropathies. Optic neuropathies are characterized by the neurodegeneration of the inner-most retinal neurons, the retinal ganglion cells (RGCs), and their axons, which form the optic nerve. Often, optic neuropathies are asymptomatic until advanced stages, when visual impairment or blindness is unavoidable despite existing treatments. In this review, we describe systemic and, whenever possible, ocular redox dysregulations observed in patients with glaucoma, ischemic optic neuropathy, optic neuritis, hereditary optic neuropathies (i.e., Leber's hereditary optic neuropathy and autosomal dominant optic atrophy), nutritional and toxic optic neuropathies, and optic disc drusen. We discuss aspects related to anti/oxidative stress biomarkers that need further investigation and features related to study design that should be optimized to generate more valuable and comparable results. Understanding the role of oxidative stress in optic neuropathies can serve to develop therapeutic strategies directed at the redox system to arrest the neurodegenerative processes in the retina and RGCs and ultimately prevent vision loss.

Hematobiochemical Disturbances and Oxidative Stress After Subacute Manganese Chloride Exposure and Potential Protective Effects of Ebselen in Rats

The present study aimed to detect the possible disturbances induced by subacute exposure to manganese chloride (MnCl2) on some biomarkers of hematology, clinical chemistry and oxidative stress, serum iron homeostasis, and ferritin status beside the histopathological alterations in hepatic and renal tissues, and the potential protective effects of ebselen on the Mn toxicity were also evaluated. Forty-eight rats were divided into four groups: Group 1 was used as a control. Groups 2, 3, and 4 were administered of ebselen as a single protective dose (15 mg/kg BW) intraperitoneal, daily manganese chloride (50 mg/kg BW) orally, and ebselen plus manganese chloride, respectively. The administrations were conducted for 30 days. Blood and tissue samples were collected at the end of the treatment for various experimental tests. Results revealed that MnCl2 did not significantly change in erythrogram with leukocytosis and neutrophilia but significantly increased serum aminotransferases and alkaline phosphatase activities, bilirubin (total, direct, and indirect), globulins, triglycerides, total cholesterol, creatinine, urea, manganese, iron and ferritin concentrations and hepatic glutathione, renal malondialdehyde and nitric oxide levels and hepatic superoxide dismutase activity, while serum albumin, hepatic malondialdehyde, and nitric oxide concentrations were significantly decreased besides non-statistical change in serum total proteins concentration. Ebselen has reduced the disturbances in these analytes in combined treatment group. Collectively, subacute exposure to MnCl2 causes disturbance in the leukogram, and hepatic and renal functions with marked renal oxidative stress. It also disturbed serum iron homeostasis and ferritin status. Remarkably, ebselen appears to be highly effective in attenuating the various adverse effects of manganese.

Relationship between high serum ferritin level and glaucoma in a South Korean population: the Kangbuk Samsung health study

BACKGROUND/AIMS

To investigate the association between serum ferritin levels and glaucoma in a South Korean population.

METHODS

This retrospective cross-sectional study included 164 029 subjects who underwent screening at Kangbuk Samsung Hospital Health Screening Center between August 2012 and July 2013. All subjects underwent a physical examination, answered sociodemographic and behavioural questions, and provided samples for laboratory analyses. A digital fundus photograph of both eyes was taken, and all photographs were reviewed by ophthalmologists. The ophthalmologists determined if an eye had glaucoma based on criteria set forth by the International Society of Geographical and Epidemiological Ophthalmology and the appearance of the retinal nerve fibre layer and optic disc.

RESULTS

The mean serum ferritin level was 56.98 ng/mL in women and 223.82 ng/mL in men. After adjusting for age, serum iron, total iron-binding capacity (TIBC), transferrin saturation, white blood cell (WBC) count, high-sensitivity C-reactive protein (HsCRP) and total vitamin D level, males in the highest quartile for serum ferritin level had a higher OR for glaucoma than males in the lowest quartile (OR=1.176, 95% CI 1.030 to 1.342, p=0.016); we did not observe this relationship among women. Other markers of iron metabolism, such as iron level, transferrin saturation and TIBC, and inflammation measures, including WBC, HsCRP and total vitamin D, were not associated with glaucoma.

CONCLUSIONS

High serum ferritin level was associated with a high risk of glaucoma in men, but not in women. Because serum ferritin is related to oxidative stress and inflammation, it might play a role in glaucoma development.

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.

Association of γ-glutamyl transferase (GGT) activity with treatment and clinical outcomes in chronic hepatitis C (HCV)

Increased γ-glutamyl transferase (GGT) activity is associated with liver injury and with mortality in the general population. Less is known about its association with chronic hepatitis C (HCV) outcomes. We examined GGT as a predictor of both virological response to treatment and long-term clinical outcomes in the Hepatitis C Anti-viral Treatment Against Cirrhosis Trial (HALT-C). HALT-C enrolled patients with advanced liver disease (Ishak fibrosis score ≥3) in two phases: a lead-in to establish lack of sustained viral response with full dose pegylated interferon (IFN) and ribavirin followed by a 3.5-year randomized trial with low-dose IFN. Low-dose IFN did not prevent liver disease progression, and patients were then followed for up to an additional 5 years off therapy. Analyses were performed for 1,319 patients who had GGT measured prior to initiation of treatment. Increases in risk with each increase in quintile of GGT (10-57, 58-89, 90-139, 140-230, 231-2,000 IU/L) were determined by logistic regression for treatment response or Cox regression for clinical outcomes. Baseline GGT was associated with male sex, nonwhite ethnicity, diabetes and insulin resistance, interleukin (IL)28B rs12979860 CT and TT genotypes, and numerous markers of liver disease injury and severity. In the lead-in phase, increasing GGT was strongly associated with diminished week 20 response, end of treatment response, and sustained virological response in both univariate and multivariate analyses controlling for factors known to be associated with treatment response (P < 0.0001). GGT was also associated with all clinical outcomes in univariate and multivariate analysis (P < 0.05) except for hepatocellular carcinoma (P = 0.46 in multivariate analysis).

CONCLUSION

GGT is an independent predictor of both virological response and clinical outcomes among patients with advanced liver disease due to HCV.

Associations of serum ferritin and transferrin % saturation with all-cause, cancer, and cardiovascular disease mortality: Third National Health and Nutrition Examination Survey follow-up study

Objectives

Even though experimental studies have suggested that iron can be involved in generating oxidative stress, epidemiologic studies on the association of markers of body iron stores with cardiovascular disease or cancer remain controversial. This study was performed to examine the association of serum ferritin and transferrin saturation (%TS) with all-cause, cancer, and cardiovascular mortality.

Methods

The study subjects were men aged 50 years or older and postmenopausal women of the Third National Health and Nutrition Examination Survey 1988-1994. Participants were followed-up for mortality through December 31, 2006.

Results

Serum ferritin was not associated with all-cause, cancer, or cardiovascular mortality for either men or postmenopausal women. However, all-cause, cancer, and cardiovascular mortality were inversely associated with %TS in men. Compared with men in the lowest quintile, adjusted hazard ratios for all-cause, cancer, and cardiovascular mortality were 0.85, 0.86, 0.76, and 0.74 (p for trend < 0.01), 0.82, 0.73, 0.75, and 0.63 (p for trend < 0.01), and 0.86, 0.81, 0.72, and 0.76 (p for trend < 0.01), respectively. For postmenopausal women, inverse associations were also observed for all-cause and cardiovascular mortality, but cancer mortality showed the significantly lower mortality only in the 2nd quintile of %TS compared with that of the 1st quintile.

Conclusions

Unlike speculation on the role of iron from experimental studies, %TS was inversely associated with all-cause, cancer and cardiovascular mortality in men and postmenopausal women. On the other hand, serum ferritin was not associated with all-cause, cancer, or cardiovascular mortality.

The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids

Ferritin iron loading was studied in the presence of physiological serum phosphate concentrations (1 mM), elevated serum concentrations (2-5 mM), and intracellular phosphate concentrations (10 mM). Experiments compared iron loading into homopolymers of H and L ferritin with horse spleen ferritin. Prior to studying the reactions with ferritin, a series of control reactions were performed to study the solution chemistry of Fe(2+) and phosphate. In the absence of ferritin, phosphate catalyzed Fe(2+) oxidation and formed soluble polymeric Fe(III)-phosphate complexes. The Fe(III)-phosphate complexes were characterized by electron microscopy and atomic force microscopy, which revealed spherical nanoparticles with diameters of 10-20 nm. The soluble Fe(III)-phosphate complexes also formed as competing reactions during iron loading into ferritin. Elemental analysis on ferritin samples separated from the Fe(III)-phosphate complexes showed that as the phosphate concentration increased, the iron loading into horse ferritin decreased. The composition of the mineral that does form inside horse ferritin has a higher iron/phosphate ratio (~1:1) than ferritin purified from tissue (~10:1). Phosphate significantly inhibited iron loading into L ferritin, due to the lack of the ferroxidase center in this homopolymer. Spectrophotometric assays of iron loading into H ferritin showed identical iron loading curves in the presence of phosphate, indicating that the ferroxidase center of H ferritin efficiently competes with phosphate for the binding and oxidation of Fe(2+). Additional studies demonstrated that H ferritin ferroxidase activity could be used to oxidize Fe(2+) and facilitate the transfer of the Fe(3+) into apo transferrin in the presence of phosphate.

Dietary micronutrient intakes are associated with markers of inflammation but not with markers of subclinical atherosclerosis

Few studies have examined associations of dietary micronutrients with markers of inflammation and subclinical atherosclerosis. The present study investigated associations of heme iron, nonheme iron, zinc (Zn), magnesium (Mg), β-carotene, vitamin C, and vitamin E with C-reactive protein (CRP), IL-6, total homocysteine (tHcy), fibrinogen, coronary artery calcium, and common and internal carotid artery intima media thickness. Micronutrient intakes and markers of inflammation and subclinical atherosclerosis were studied in 5,181 participants from the Multi-Ethnic Study of Atherosclerosis who were aged 45-84 y and free of diabetes and cardiovascular disease. Models were adjusted for energy intake, demographics, lifestyle characteristics, and BMI. Dietary nonheme iron and Mg intakes were inversely associated with tHcy concentrations (mean tHcy: 9.11, 8.86, 8.74, 8.71, and 8.50 μmol/L, and 9.20, 9.00, 8.65, 8.76, and 8.33 μmol/L across increasing quintiles of nonheme iron and Mg, respectively; P-trend < 0.001 for both). However, dietary Zn and heme iron were positively associated with CRP [mean: 1.73, 1.75, 1.78, 1.88, and 1.96 mg/L across increasing quintiles of Zn and 1.72, 1.76, 1.83, 1.86, and 1.94 mg/L across increasing quintiles of heme iron (P-trend = 0.002 and 0.01, respectively). Other tested micronutrient-marker associations were not significant. In conclusion, of the 49 tested associations, only 7 were significant. Although this study does not provide strong support for associations between the micronutrients and markers of inflammation and subclinical atherosclerosis, the results are consistent with dietary guidelines that advocate for a balanced diet that includes a variety of plant foods containing Mg, Zn, and nonheme iron.

Altered oxidative state in schoolchildren with asthma and allergic rhinitis

Oxidative stress may be defined as a disruption of the balance between the level of oxidants and reductants (antioxidants), and oxidative state in children may influence the risk of asthma and allergic disease. We investigated serum antioxidant levels: selenium, vitamin E, bilirubin, albumin, uric acid and transferrin as well as the oxidant ferritin and their association with asthma and allergic rhinitis. Children of 7-12 yr with asthma (n = 50) and no asthma (controls) (n = 52) underwent skin prick test, lung function, fractional exhaled nitric oxide (FeNO) measurements and blood sampling. Allergic rhinitis was found in 23 children, 19 with asthma and four controls. Healthy children were controls without rhinitis. Asthma was associated with reduced albumin (g/l), adjusted odds ratio (aOR) (95% CI) 0.81 (0.66, 0.99) (p = 0.048) compared with healthy children in a regression analysis adjusted for age and gender. Asthma with high FeNO ≥20 ppb was associated with reduced albumin, aOR 0.60 (0.40, 0.89) (p = 0.012) compared to controls with FeNO <20. Asthma with allergic rhinitis had reduced albumin, aOR = 0.70 (0.50, 0.99) (p = 0.04), and higher ferritin levels (mg/l) [aOR = 1.04 (1.00, 1.09) p = 0.03] compared to healthy children. Poorly controlled asthma was associated with lower vitamin E levels, aOR 0.79 (0.65, 0.95) (p = 0.02), lower transferrin levels, aOR 0.72 (0.57, 0.92) (p < 0.01), and higher albumin levels, aOR 1.53 (1.03, 2.28) (p = 0.04), compared to well controlled asthma. In conclusion, schoolchildren with asthma and rhinitis had reduced levels of the major serum antioxidant albumin, and poorly controlled asthma was associated with decreased vitamin E and transferrin levels. Reduced albumin was associated with increased FeNO, a marker of allergic inflammation in asthma, although the discriminatory value of this finding should be further assessed in population studies.

Iron status is associated with carotid atherosclerotic plaques in middle-aged adults

Although the iron-heart disease hypothesis is prevalent, the epidemiological findings are incongruent. The relationship of serum ferritin with early cardiovascular disease (CVD), particularly atherosclerosis, has not been evaluated extensively, particularly with accounting for inflammation. We examined this association in a case-control study of 124 age- and sex-matched pairs embedded in the population-based random sample (MONICA survey) in Southwest France, taking into account inflammation status. Cases had >or=2 carotid atherosclerotic plaques and controls had none. Inflammation was assessed using several markers, including serum alpha-1 acid glycoprotein (AGP) and high sensitivity C-reactive protein. There was an interaction of inflammation with group (case/control) for serum ferritin. In adults without elevated AGP, serum ferritin was significantly greater in atherosclerotic cases than in adults in the control group. In models adjusted for CVD risk factors, the odds of atherosclerosis increased with the increase in serum ferritin in individuals without elevated AGP; for every 10-microg/L increase in serum ferritin, the risk for atherosclerosis increased by 3% (odds ratio [95% CI]: 1.03 [1.01-1.06]). In conclusion, carotid atherosclerosis was positively associated with serum ferritin in individuals free from subclinical inflammation based on AGP. Further prospective and/or experimental studies are needed to corroborate the observed association of iron status with atherosclerosis.

Ferritin levels, inflammatory biomarkers, and mortality in peripheral arterial disease: a substudy of the Iron (Fe) and Atherosclerosis Study (FeAST) Trial

BACKGROUND

This study delineated correlations between ferritin, inflammatory biomarkers, and mortality in a cohort of 100 cancer-free patients with peripheral arterial disease (PAD) participating in the Veterans Affairs (VA) Cooperative Study #410, the Iron (Fe) and Atherosclerosis Study (FeAST). FeAST, a prospective, randomized, single-blind clinical trial, tested the hypothesis that reduction of iron stores using phlebotomy would influence clinical outcomes in 1227 PAD patients randomized to iron reduction or control groups. The effects of statin administration were also examined in the Sierra Nevada Health Care (SNHC) cohort by measuring serum ferritin levels at entry and during the 6-year study period. No difference was documented between treatment groups in all-cause mortality and secondary outcomes of death plus nonfatal myocardial infarction and stroke. Iron reduction in the main study caused a significant age-related improvement in cardiovascular disease outcomes, new cancer diagnoses, and cancer-specific death.

METHODS

Tumor necrosis factor (TNF)-alpha, TNF-alpha receptors 1 and 2, interleukin (IL)-2, IL-6, IL-10, and high-sensitivity C reactive protein (hs-CRP) were measured at entry and at 6-month intervals for 6 years. Average levels of ferritin and lipids at entry and at the end of the study were compared. The clinical course and ferritin levels of 23 participants who died during the study were reviewed.

RESULTS

At entry, mean age of entry was 67 +/- 9 years for the SNHCS cohort, comparable to FeAST and clinical and laboratory parameters were equivalent in substudy participants randomized to iron reduction (n = 51) or control (n = 49). At baseline, 53 participants on statins had slightly lower mean entry-level ferritin values (114.06 ng/mL; 95% confidence interval [CI] 93.43-134.69) vs the 47 off statins (127.62 ng/mL; 95% CI, 103.21-152.02). Longitudinal analysis of follow-up data, after adjusting for the phlebotomy treatment effect, showed that statin use was associated with significantly lower ferritin levels (-29.78 ng/mL; Cohen effect size, -0.47 [t(df, 134) = 2.33, P = .02]). Mean follow-up average ferritin levels were higher in 23 participants who died (132.5 ng/mL; 95% CI, 79.36-185.66) vs 77 survivors (83.6 ng/mL; 95% CI, 70.34-96.90; Wilcoxon P = .05). Mean follow-up IL-6 levels were higher in dead participants (21.68 ng/mL; 95% CI, 13.71-29.66) vs survivors (12.61 ng/mL; 95% CI, 10.72-14.50; Wilcoxon P = .018). Ferritin levels correlated (Pearson) with average IL-6 levels (r = 0.1845; P = .002) and hsCRP levels (r = .1175; P = .04) during the study.

CONCLUSION

These data demonstrate statistical correlations between levels of ferritin, inflammatory biomarkers, and mortality in this subset of patients with PAD.

Body iron store as a predictor of oxidative DNA damage in healthy men and women

While iron plays an important role in many cellular functions, excess iron storage induces DNA damage by generating hydroxyl radicals and thus promotes carcinogenesis. However, it remains unclear whether body iron levels that are commonly observed in a general population are related to oxidative DNA damage. We examined the association between serum ferritin concentrations and levels of urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of systemic oxidative DNA damage and repair, in 528 Japanese men and women aged 21-67 years. Men had much higher ferritin levels than in women, and the levels were significantly greater in women aged 50 years or older than in women aged less than 50 years. Urinary 8-OHdG concentrations were significantly and positively associated with serum ferritin levels in all the subgroups. The Spearman rank correlation coefficients were 0.47, 0.76, and 0.73 for men overall, women aged less than 50 years, and women aged 50 years or older, respectively. These associations were materially unchanged after adjustment for potential confounding variables. In men, a more pronounced association was observed in nonsmokers than in smokers. Our results suggest body iron storage is a strong determinant of levels of systemic oxidative DNA damage in a healthy population.

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.

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.

Studies on resistance characteristic and cDNA sequence conservation of transferrin from crucian carp, Carassius auratus

Transferrin (Tf) is a kind of non-heme beta-globulin with two iron ions (Fe(3+))-binding sites. To prove Tf's physiological functions, Fe(3+)-proteins, serum iron contents, and total iron-binding capabilities were tested for Tfs of crucian carps (Carassius auratus) and sliver carps (Hypophthalmichthys molitrix). The above results demonstrated that sliver carps shared 1/3 Tf alleles with crucian carps; Tf of crucian carps had stronger Fe(3+)-binding ability and transportation ability in plasma than that of sliver carps. In addition, the results of oxygen consumption experiments indicated that crucian carps had the higher oxygen utility rate than sliver carps. For acute hypoxia exposure assay, normoxic gas mixture, hypoxic gas mixture A, and hypoxic gas mixture B were used to induce oxygen-regulated gene expression of crucian carps in acute hypoxia. The results of quantitative real-time PCR revealed that mRNA levels of Tf gene, Tfr gene and ATPase gene were down-regulated in acute hypoxia but mRNA level of LDHa gene was up-regulated in acute hypoxia. The results of crucian carp Tf-cDNA sequence analysis showed that cDNA regions of two Fe(3+)-binding sites were T(747)-T(1026) and T(1737)-A(1884) based on the principle of bioinformatics. The sequence conservation of two Fe(3+)-binding sites was higher than that of the other five regions, which were confirmed according to the subregion model of Tf-cDNA sequence.