Andrew P Levy

Technion - Israel Institute of Technology, H̱efa, Haifa, Israel

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Publications (119)776.41 Total impact

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    ABSTRACT: Background Research targeting glycosylated hemoglobin A1c (HbA1c) to <6.5% to prevent coronary heart disease (CHD) events has conflicting results. We previously observed the haptoglobin (Hp) Hp2-2 genotype is associated with a ∼10-fold increased CHD risk among individuals with HbA1c <6.5%, and thus might be useful in identifying those at high risk of CHD who would benefit from maintaining HbA1c <6.5%. Objectives This study sought to model whether HbA1c < 6.5% in the Hp2-2 genotype is associated with CHD in a prospective case-control study nested within the Health Professionals Follow-Up Study (HPFS). Methods HbA1c concentration and Hp genotype were determined for 695 incident cases of CHD from 1994 to 2010 and matched control participants. Logistic regression models calculated relative risk (RR) and 95% CI, for the first and second halves of follow-up, adjusting for confounding variables. A dataset from the Nurses' Health Study served as a replication cohort. Results The prevalence of the Hp2-2 genotype in HPFS was 39%. Compared with HbA1c <6.5%, the RR of CHD for HbA1c <6.5% for the Hp2-2 genotype over full follow-up was 3.07 (95% CI: 1.37 to 6.86) to 3.88 (95% CI: 1.31 to 11.52) during the first half of follow-up and 2.16 (95% CI: 0.61 to 7.61) in the second half. The corresponding RRs for the Hp1-1 + Hp2-1 genotypes were: full follow-up, 2.19 (95% CI: 1.14 to 4.24); first half, 1.60 (95% CI: 0.73 to 3.53); and second half, 4.72 (95% CI: 1.26 to 17.65). Conclusions In 2 independent cohorts, the risk of CHD associated with HbA1c <6.5% is pronounced in the Hp2-2 genotype, particularly in early cases. The Hp2-2 genotype may identify individuals at greatest CHD risk from hyperglycemia.
    No preview · Article · Oct 2015 · Journal of the American College of Cardiology
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    ABSTRACT: Background: Haptoglobin (Hp) genotype has been shown to be a predictor of clinical outcomes in subarachnoid hemorrhage. Cerebral salt wasting (CSW) has been suggested to precede the development of symptomatic vasospasm. Objective: To determine if Hp genotype was associated with CSW and subsequent vasospasm after aneurysmal subarachnoid hemorrhage. Methods: Hp genotypic determination was done for patients admitted with a diagnosis of subarachnoid hemorrhage. Outcome measures included CSW, delayed cerebral infarction, and Glasgow Outcome Score of 4 to 5 at 30 days. Criteria for CSW included hyponatremia <135 mEq/L, and urine output >4 L in 12 hours with urine sodium >40 mEq/L. Results: A total of 133 patients were included in the study. The 3 Hp subgroups did not differ in terms of baseline characteristics. CSW occurred in 1 patient (3.4%) with Hp 1-1, 8 (14.0%) patients with Hp 2-1, and 15 (31.9%) patients with Hp 2-2 (P = .004). In the multivariate regression model, Hp 2-2 was associated with CSW (odds ratio [OR]: 4.94; CI: 1.78-17.43; P = .01), but Hp 2-1 was not (OR: 2.92; CI: 0.56-4.95; P = .15) compared with Hp 1-1. There were no associations between Hp genotypes and functional outcome or delayed cerebral infarction. CSW was associated with delayed cerebral infarction (OR: 7.46; 95% CI: 2.54-21.9; P < .001). Conclusion: Hp 2-2 genotype was an independent predictor of CSW after subarachnoid hemorrhage. Because CSW is strongly associated with delayed cerebral infarction, the use of Hp genotype testing requires more investigation, and larger prospective confirmation is warranted. Additionally, a more objective definition of CSW needs to be delineated. Abbreviations: CSW, cerebral salt wastingDCI, delayed cerebral ischemiaGOS, Glasgow Outcome ScaleHp, HaptoglobinmRS, modified Rankin ScaleSAH, subarachnoid hemorrhageTCD, transcranial Doppler.
    Full-text · Article · Sep 2015 · Neurosurgery
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    ABSTRACT: Elevated systolic pulmonary artery pressure (s-PAP, ≥35 mmHg) serves as an independent predictor of mortality in hemodialysis (HD) and diabetic (DM) patients. A polymorphism in the antioxidant Haptoglobin (Hp) gene has been shown to regulate the bioavailability of nitric oxide (NO), a major mediator of pulmonary vascular tone. We therefore set out to test the hypothesis that the Hp polymorphism may be a determinant of developing elevated s-PAP specifically in the DM state due to a decreased bioavailability of NO. To test our hypothesis we Hp typed and performed transthoracic echocardiography on a series of HD patients and stratified them into elevated and normal s-PAP groups and then evaluated whether there was a significant association between the Hp type, elevated s-PAP, and decreased NO bioavailability as defined by low plasma nitrite. We found a statistically significant interaction between the Hp type and DM on the prevalence of elevated s-PAP and lower mean nitrite levels with the combination of elevated s-PAP and low nitrite levels being significantly more prevalent in Hp 2-2 DM individuals. We conclude that the Hp 2 type is associated with elevated s-PAP levels and low plasma nitrite levels in HD patients specifically in the DM state.
    Full-text · Article · Jul 2015 · Journal of Diabetes Research
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    ABSTRACT: Haptoglobin (Hp) genotype 2-2 increases cardiovascular diabetes complications. In type 2 diabetes, α-tocopherol was shown to lower cardiovascular risk in Hp 2-2, potentially through HDL function improvements. Similar type 1 diabetes data are lacking. We conducted a randomized crossover pilot of α-tocopherol supplementation on HDL function [i.e., cholesterol efflux (CE) and HDL-associated lipid peroxides (LP)] and lipoprotein subfractions in type 1 diabetes. Hp genotype was assessed in members of two Allegheny County, PA, type 1 diabetes registries and the CACTI cohort; 30 were randomly selected within Hp genotype, and 28 Hp 1-1, 31 Hp 2-1 and 30 Hp 2-2 were allocated to daily α-tocopherol or placebo for 8 weeks with a 4-week washout. Baseline CE decreased with the number of Hp 2 alleles (p-trend = 0.003). There were no differences in LP or lipoprotein subfractions. In intention-to-treat analysis stratified by Hp, α-tocopherol increased CE in Hp 2-2 (β = 0.79, p = 0.03) and LP in Hp 1 allele carriers (β Hp 1-1 = 0.18, p = 0.05; β Hp 2-1 = 0.21, p = 0.07); reduced HDL particle size (β = -0.07, p = 0.03) in Hp 1-1 carriers; increased LDL particle concentration in Hp 1-1; and decreased it in Hp 2-2 carriers. However, no significant interactions were observed by Hp. In this type 1 diabetes study, HDL function worsened with the number of Hp 2 alleles. α-Tocopherol improved HDL function in Hp 2-2 carriers and appeared to adversely affect lipid peroxides and lipoprotein subfractions among Hp 1 allele carriers. As no significant interactions were observed, findings require replication in larger studies.
    No preview · Article · May 2015 · Acta Diabetologica
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    ABSTRACT: Homozygosity for a 1.7 kb intragenic duplication of the Haptoglobin (Hp) gene (Hp 2-2 genotype), present in 36% of the population, has been associated with a 2-3 fold increased incidence of atherothrombosis in individuals with Diabetes (DM) in 10 longitudinal studies compared to DM individuals not homozygous for this duplication (Hp 1-1/2-1). The increased CVD risk associated with the Hp 2-2 genotype has been shown to be prevented with vitamin E supplementation in man. We sought to determine if there was an interaction between the Hp genotype and vitamin E on atherosclerotic plaque growth and stability in a transgenic model of the Hp polymorphism. Brachiocephalic artery atherosclerotic plaque volume was serially assessed by high resolution ultrasound in 28 Hp 1-1 and 26 Hp 2-2 mice in a C57Bl/6 ApoE(-/-) background. Hp 2-2 mice had more rapid plaque growth and an increased incidence of plaque hemorrhage and rupture. Vitamin E significantly reduced plaque growth in Hp 2-2 but not in Hp 1-1 mice with a significant pharmacogenomic interaction between the Hp genotype and vitamin E on plaque growth. These results may help explain why vitamin E supplementation in man can prevent CVD in Hp 2-2 DM but not in non Hp 2-2 DM individuals. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Preview · Article · Jan 2015 · Atherosclerosis
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    ABSTRACT: Objective: To determine if the haptoglobin (Hp) phenotype, which has been shown to be a predictor of clinical outcomes in cerebrovascular disorders, particularly subarachnoid hemorrhage, was predictive of functional outcomes after spontaneous intracerebral hemorrhage (ICH). Methods: Patients admitted with a diagnosis of ICH were prospectively included and divided into 3 groups based on their genetically determined Hp phenotype: 1-1, 2-1, and 2-2. Outcome measures included mortality and 30-day modified Rankin Scale scores. Demographics and outcomes were compared for each phenotype using multivariate linear regression analysis. Results: The study included 94 patients. The distribution of Hp phenotype was Hp 1-1, 12 (13%); Hp 2-1, 46 (49%); and Hp 2-2, 36 (38%). The 3 Hp subgroups did not differ in terms of demographic variables, comorbidities, or ICH characteristics. There was a nonsignificant trend toward increased mortality in Hp 2-1 and Hp 2-2 compared with Hp 1-1, with mortality of 8% in Hp 1-1, 17% in Hp 2-1, and 25% in Hp 2-2 (P = 0.408). In the regression model adjusted for confounders, Hp 2-1 (odds ratio = 0.05, 95% confidence interval = 0.01-0.47, P < 0.001) and Hp 2-2 phenotypes (odds ratio = 0.14, 95% confidence interval = 0.02-0.86, P = 0.045) had significantly lower odds of modified Rankin Scale scores 0-2 compared with Hp 1-1. Conclusions: After ICH, individuals with the Hp-2 allele (2-1 and 2-2) had worse functional outcomes than individuals with the Hp-1 allele (Hp 1-1). There was a nonsignificant association between Hp phenotype and mortality. Larger prospective studies with better surrogates of ICH outcomes are warranted.
    Full-text · Article · Dec 2014 · World Neurosurgery
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    ABSTRACT: The major function of the Haptoglobin (Hp) protein is to control trafficking of extracorpuscular hemoglobin (Hb) thru the macrophage CD163 receptor with degradation of the Hb in the lysosome. There is a common copy number polymorphism in the Hp gene (Hp 2 allele) which has been associated with a several fold increased incidence of atherothrombosis in multiple longtidinal studies. Increased plaque oxidation and apoptotic markers have been observed in Hp 2-2 atherosclerotic plaques but the mechanism responsible for this finding has not been determined. We proposed that the increased oxidative injury in Hp 2-2 plaques is due to an impaired processing of Hp 2-2-Hb complexes within macrophage lysosomes thereby resulting in redox active iron accumulation, lysosomal membrane oxidative injury and macrophage apoptosis. We sought to test this hypothesis in vitro using purified Hp-Hb complex and cells genetically manipulated to express CD163. CD163 mediated endocytosis and lysosomal degradation of Hp-Hb were decreased for Hp 2-2-Hb complexes. Confocal microscopy, using lysotropic pH indicator dyes, demonstrated that uptake of Hp 2-2-Hb complexes disrupted the lysosomal pH gradient. Cellular fractionation studies of lysosomes isolated from macrophages incubated with Hp 2-2-Hb complexes demonstrated increased lysosomal membrane oxidation and a loss of lysosomal membrane integrity leading to lysosomal enzyme leakage into the cytoplasm. Additionally, markers of apoptosis, DNA fragmentation and active caspase-3 were increased in macrophages which had endocytosed Hp 2-2-Hb complexes. These data provide novel mechanistic insights into how the Hp genotype regulates lysosomal oxidative stress within macrophages following receptor-mediated endocytosis of Hb.
    Preview · Article · Apr 2014 · Journal of Biological Chemistry

  • No preview · Article · Mar 2014 · Atherosclerosis

  • No preview · Article · Dec 2013 · International journal of cardiology
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    ABSTRACT: Diabetes mellitus (DM) is associated with increased oxidative stress due to elevated glucose levels in the plasma. Glucose promotes glycosylation of both plasma and cellular proteins with increased risk for vascular events. Diabetic patients suffer from a higher incidence of cardiovascular complications such as diabetic nephropathy. Haptoglobin (Hp) is an antioxidant plasma protein which binds free hemoglobin, thus preventing heme-iron mediated oxidation. Two alleles exist at the Hp gene locus (1 and 2) encoding three possible Hp genotypes that differ in their antioxidant ability, and may respond differently to vitamin E treatment. Several clinical studies to have shown that Hp 1-1 genotype is a superior antioxidant to the Hp 2-2 genotype and Hp 2-2 genotype is associated with a higher incidence of cardiovascular disease. Vitamin E was found to have beneficial effect in patient and mice with Hp 2-2 genotype. In this review we have summarized the results of our studies in patients with diabetic nephropathy treated with vitamin E and in diabetic mice with different haptoglobin genotypes.
    No preview · Article · Nov 2013
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    Preview · Article · Jun 2013 · Journal of the American College of Cardiology
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    ABSTRACT: The haptoglobin (Hp) protein has been implicated in various aspects of reproduction. One possible mechanism is through its effect on angiogenesis. Angiogenesis plays a major role in follicle production. The Hp insertion polymorphism results in the production of Hp proteins denoted Hp 1-1, 2-1, and 2-2, with markedly different angiogenic activities. We sought to determine if the number of oocytes aspirated during in vitro fertilization is related to the Hp type and to compare clinical data and treatment outcomes. We conducted a prospective non-interventional study in an academic in vitro fertilization center serving northern Israel. All patients undergoing in vitro fertilization who agreed to have their haptoglobin phenotype and clinical data evaluated anonymously were included. The main outcome measure was the number of oocytes harvested from each aspiration. The groups did not differ regarding ethnicity or BMI, though women with the Hp1-1 phenotype had a longer duration of infertility (p = 0.037) and a higher gonadotropin requirement (p = 0.024) to achieve the same treatment outcome. Women with mechanical factor infertility were more likely (p = 0.042) to have the Hp 1-1/2-1 phenotypes than the Hp2-2 phenotype. There were no differences in the number of oocytes aspirated or the pregnancy rate. In summary, we could not establish a correlation between Hp phenotype and oocyte number or IVF outcomes though the Hp2-2 phenotype may be protective against mechanical factor infertility. Further studies with a larger sample size, particularly concerning the Hp1-1 phenotype, are required in order to extend these results.
    No preview · Article · May 2013 · Systems biology in reproductive medicine
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    Moshe Vardi · Nina S Levy · Andrew P Levy
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    ABSTRACT: Vitamin E is a naturally occurring fat-soluble antioxidant which has been proposed as a treatment for both primary and secondary protection against cardiovascular (CV)events. Promising data from observational epidemiological studies associating higher vitamin E dietary intake with lower risk of CV events have not been validated in randomized, controlled clinical trials assessing the effect of vitamin E on CV outcomes. While the pendulum of medical opinion has swung to suggest that high dose vitamin E supplements have no place in the treatment and prevention of CV disease, new data is emerging that allows identification of a specific target population for this treatment, namely patients with Diabetes Mellitus and the haptoglobin genotype 2-2. This review details the scientific basis and clinical evidence related to the effect of vitamin E on CV outcomes, and the importance of proper patient selectionin gaining therapeutic benefit from this intervention.
    Preview · Article · Mar 2013 · The Journal of Lipid Research
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    ABSTRACT: Background: Haptoglobin (Hp) is an abundant serum protein which binds extracorpuscular hemoglobin (Hb). Two alleles exist in humans for the Hp gene, denoted 1 and 2. Diabetic individuals with the Hp 2-2 genotype are at increased risk of developing vascular complications including heart attack, stroke, and kidney disease. Recent evidence shows that treatment with vitamin E can reduce the risk of diabetic vascular complications by as much as 50% in Hp 2-2 individuals. We sought to develop a rapid and accurate test for Hp phenotype (which is 100% concordant with the three major Hp genotypes) to facilitate widespread diagnostic testing as well as prospective clinical trials. Methods: A monoclonal antibody raised against human Hp was shown to distinguish between the three Hp phenotypes in an enzyme linked immunosorbent assay (ELISA). Hp phenotypes obtained in over 8000 patient samples using this ELISA method were compared with those obtained by polyacrylamide gel electrophoresis or the TaqMan PCR method. Results: Our analysis showed that the sensitivity and specificity of the ELISA test for Hp 2-2 phenotype is 99.0% and 98.1%, respectively. The positive predictive value and the negative predictive value for Hp 2-2 phenotype is 97.5% and 99.3%, respectively. Similar results were obtained for Hp 2-1 and Hp 1-1 phenotypes. In addition, the ELISA was determined to be more sensitive and specific than the TaqMan method. Conclusions: The Hp ELISA represents a user-friendly, rapid and highly accurate diagnostic tool for determining Hp phenotypes. This test will greatly facilitate the typing of thousands of samples in ongoing clinical studies.
    No preview · Article · Mar 2013 · Clinical Chemistry and Laboratory Medicine
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    ABSTRACT: Diabetic nephropathy (DN) is the leading cause of end stage renal disease and dialysis worldwide. Despite aggressive treatment, the number of patients on hemodialysis due to type 1 and type 2 diabetes mellitus is increasing annually. The lack of reliable animal models that mimic human disease has delayed the identification of specific factors that cause or predict DN. Different investigators around the world are testing different murine models. Validation criteria for early and advanced DN, phenotypic methods, background strain have recently been developed. Establishment of an authentic mouse model of DN will undoubtedly facilitate the understanding of the underlying genetic mechanisms that contribute to the development of DN and to study new treatments. Here we describe the characteristics of our new mouse model with type 1 diabetes mellitus and different haptoglobin genotypes that can mimic human DN.
    No preview · Article · Mar 2013 · Diabetes research and clinical practice
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    ABSTRACT: In diabetes, there is an increase in oxidative stress due to elevated glucose levels in the plasma. High glucose promotes glycosylation, of both plasma and cellular proteins, which particularly affects the endothelial-cell lining of the blood vessel wall and interferes with its normal function. Thus, diabetes mellitus patients suffer from a higher incidence of cardiovascular complications such as atherosclerosis as compared with the nondiabetic population. Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and prevents heme-iron mediated oxidation. There are three different types of Hp, which differ in their antioxidant ability. Several clinical studies have shown that the Hp 2-2 genotype is associated with higher incidence of cardiovascular diseases among diabetics. Vitamin E, a low-cost, easy-to-use antioxidant, was found to decrease the risk of developing cardiovascular diseases in Hp 2-2 diabetic patients. This review summarizes several studies that show the importance of vitamin E supplementation in a specific subgroup of patients, diabetic individuals carrying the Hp 2-2 genotype.
    Preview · Article · Mar 2013 · Expert Review of Cardiovascular Therapy
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    ABSTRACT: OBJECTIVES: This study sought to investigate into the biologically plausible interaction between the common haptoglobin (Hp) polymorphism rs#72294371 and glycosylated hemoglobin (HbA(1c)) on risk of coronary heart disease (CHD). BACKGROUND: Studies of the association between the Hp polymorphism and CHD report inconsistent results. Individuals with the Hp2-2 genotype produce Hp proteins with an impaired ability to prevent oxidative injury caused by elevated HbA(1c). METHODS: HbA(1c) concentration and Hp genotype were determined for 407 CHD cases matched 1:1 to controls (from the NHS [Nurses' Health Study]) and in a replication cohort of 2,070 individuals who served as the nontreatment group in the ICARE (Israel Cardiovascular Events Reduction With Vitamin E) study, with 29 CHD events during follow-up. Multivariate models were adjusted for lifestyle and CHD risk factors as appropriate. A pooled analysis was conducted of NHS, ICARE, and the 1 previously published analysis (a cardiovascular disease case-control sample from the Strong Heart Study). RESULTS: In the NHS, Hp2-2 genotype (39% frequency) was strongly related to CHD risk only among individuals with elevated HbA(1c) (≥6.5%), an association that was similar in the ICARE trial and the Strong Heart Study. In a pooled analysis, participants with both the Hp2-2 genotype and elevated HbA(1c) had a relative risk of 7.90 (95% confidence interval: 4.43 to 14.10) for CHD compared with participants with both an Hp1 allele and HbA(1c) <6.5% (p for interaction = 0.004), whereas the Hp2-2 genotype with HbA(1c) <6.5% was not associated with risk (relative risk: 1.34 [95% confidence interval: 0.73 to 2.46]). CONCLUSIONS: Hp genotype was a significant predictor of CHD among individuals with elevated HbA(1c).
    Full-text · Article · Jan 2013 · Journal of the American College of Cardiology
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    Moshe Vardi · Shany Blum · Andrew P Levy
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    ABSTRACT: Diabetes mellitus carries a high risk for vascular events. Diabetics with different haptoglobin (Hp) types may carry different risk profiles, and may respond differently to vitamin E treatment. We aim to summarize the evidence about cardiovascular risk in diabetic patients, according to their Hp type, and the effect of vitamin E treatment on these sub-groups. We searched MEDLINE and on-going trials' databases until February 2011; gray literature; reference lists of identified articles; and experts. Two investigators screened and selected studies that prospectively followed cardiovascular outcomes in diabetic patients with different Hp types (natural history analysis), and randomized controlled trials reporting the effect of vitamin E on cardiovascular outcomes in diabetics, in which Hp typing was performed (interventional analysis). Five and three studies, comprising 1829 and 2110 patients, were eligible for the natural history and the interventional analyses, respectively. The percentage of diabetic patients experiencing non-fatal MI, stroke, or cardiovascular death was significantly higher in the Hp 2-2 population (odds ratio (OR) 2.03 (95% confidence interval (CI) 1.46 to 2.81)). In patients with Hp 2-2 genotype, the OR for a combined endpoint was 0.66 in favor of the vitamin E treated group (95% CI 0.48 to 0.9). This effect was not shown in other Hp types. Hp type 2-2 carries a high risk of cardiovascular events in diabetic patients. A pharmacogenomic approach towards treatment of diabetic patients with vitamin E may be warranted.
    Full-text · Article · Oct 2012 · European Journal of Internal Medicine
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    ABSTRACT: The purpose of this study was to test the hypothesis that increased oxidative stress is associated with apoptosis in human plaques with the haptoglobin (Hp) 2-2 genotype. Intraplaque hemorrhage releases free hemoglobin (Hb). Impaired Hb clearance induces oxidative stress leading to plaque progression. The binding of Hp to Hb attenuates iron-induced oxidative reactions. Twenty-six human aortic plaques were Hp genotyped. Hp2-2 plaques (n = 13) were compared with control (Hp1-1/2-1) (n = 13). The iron grade was measured by Perl's staining. Immunostaining was used to detect oxidation-specific epitopes (OSEs) reflecting oxidized phospholipids and malondialdehyde-like epitopes. The percentages of apoptotic cells and apoptotic morphological features were quantified. DNA fragmentation and active caspase-3 were measured by in situ end-labeling and immunohistochemistry, respectively. In Hp2-2 plaques, iron content was increased (1.22 ± 0.15 vs. 0.54 ± 0.08; p < 0.0001) along with expression of oxidized phospholipid- (78.9 ± 5.8 vs. 38.8 ± 3.8; p < 0.0001), and malondialdehyde-like OSEs (93.9 ± 7.9 vs. 54.7 ± 3.9; p < 0.0001). The total percentages of apoptotic cells (11.9 ± 0.44 vs. 3.5 ± 0.28; p < 0.0001), nuclear fragmentation (11.8 ± 0.50 vs. 3.3 ± 0.26; p < 0.0001), nuclear condensation (10.9 ± 0.58 vs. 3.4 ± 0.20; p < 0.0001), chromatin margination (14.2 ± 0.57 vs. 6.5 ± 0.37; p < 0.0001), cytoplasmic blebs (1.6 ± 0.28 vs. 0.8 ± 0.14; p < 0.002), and eosinophilia (10.8 ± 0.74 vs. 4.2 ± 0.27; p < 0.0001) were increased in Hp2-2 plaques. Furthermore, DNA fragmentation (119.9 ± 1.40 vs. 57.5 ± 0.80; p < 0.001), and active caspase-3 density (84.7 ± 7.62 vs. 50.6 ± 7.49; p < 0.004) were increased in Hp2-2 plaques. Logistic regression analysis identified correlation between the percentage of apoptotic cells and the density of OSEs (r = 0.56; p < 0.003). These findings provide insights into genetic predisposition to oxidative stress and the relationship between OSEs and macrophage apoptosis that may explain advanced atherosclerosis in human Hp2-2 plaques.
    Preview · Article · Jul 2012 · Journal of the American College of Cardiology
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    ABSTRACT: The haptoglobin (Hp) genotype is a major determinant of progression of nephropathy in individuals with diabetes mellitus (DM). The major function of the Hp protein is to bind and modulate the fate of extracorpuscular hemoglobin and its iron cargo. We have previously demonstrated an interaction between the Hp genotype and the DM on the accumulation of iron in renal proximal tubule cells. The primary objective of this study was to determine the intracellular localization of this iron in the proximal tubule cell and to assess its potential toxicity. Transmission electron microscopy demonstrated a marked accumulation of electron-dense deposits in the lysosomes of proximal tubules cells in Hp 2-2 DM mice. Energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy were used to perform elemental analysis of these deposits and demonstrated that these deposits were iron rich. These deposits were associated with lysosomal membrane lipid peroxidation and loss of lysosomal membrane integrity. Vitamin E administration to Hp 2-2 DM mice resulted in a significant decrease in both intralysosomal iron-induced oxidation and lysosomal destabilization. Iron-induced renal tubular injury may play a major role in the development of diabetic nephropathy and may be a target for slowing the progression of renal disease.
    Full-text · Article · Jun 2012 · Free Radical Biology and Medicine

Publication Stats

4k Citations
776.41 Total Impact Points


  • 2000-2015
    • Technion - Israel Institute of Technology
      • Ruth and Bruce Rappaport Faculty of Medicine
      H̱efa, Haifa, Israel
  • 2013
    • Harvard University
      • Department of Nutrition
      Cambridge, Massachusetts, United States
  • 2010-2011
    • Mount Sinai Medical Center
      New York, New York, United States
    • Icahn School of Medicine at Mount Sinai
      Borough of Manhattan, New York, United States
  • 2007
    • Duke University
      Durham, North Carolina, United States
    • Rambam Medical Center
      • Department of Nephrology
      Haifa, Haifa District, Israel
    • The Rockefeller University
      New York, New York, United States
  • 2004
    • University of Ottawa
      Ottawa, Ontario, Canada
    • Hebrew University of Jerusalem
      • Department of Biological Chemistry
      Yerushalayim, Jerusalem, Israel
  • 1997
    • Georgetown University
      • Division of Cardiology
      Washington, Washington, D.C., United States