Tissue Iron Accumulation Research Articles

A Probable Risk Factor of Female Breast Cancer: Study on Benign and Malignant Breast Tissue Samples

The study reports enhanced Fe, Cu, and Zn contents in breast tissues, a probable risk factor of breast cancer in females. Forty-one formalin-fixed breast tissues were analyzed using atomic absorption spectrophotometry. Twenty malignant, six adjacent to malignant and 15 benign tissues samples were investigated. The malignant tissues samples were of grade 11 and type invasive ductal carcinoma. The quantitative comparison between the elemental levels measured in the two types of specimen (benign and malignant) tissues (removed after surgery) suggests significant elevation of these metals (Fe, Cu, and Zn) in the malignant tissue. The specimens were collected just after mastectomy of women aged 19 to 59 years from the hospitals of Islamabad and Rawalpindi, Pakistan. Most of the patients belong to urban areas of Pakistan. Findings of study depict that these elements have a promising role in the initiation and development of carcinoma as consistent pattern of elevation for Fe, Cu, and Zn was observed. The results showed the excessive accumulation of Fe (229 ± 121 mg/L) in malignant breast tissue samples of patients (p < 0.05) to that in benign tissues samples (49.1 ± 11.4 mg/L). Findings indicated that excess accumulation of iron in malignant tissues can be a risk factor of breast cancer. In order to validate our method of analysis, certified reference material muscle tissue lyophilized (IAEA) MA-M-2/TM was analyzed for metal studied. Determined concentrations were quite in good agreement with certified levels. Asymmetric concentration distribution for Fe, Cu, and Zn was observed in both malignant and benign tissue samples.

Pancreatic Iron and Fat Infiltration Are Diabetogenic Risk Factors In Patients With Iron Overload

IntroductionChronically transfused patients and patients with hereditary hemochromatosis (HHC) are affected by complications due to excessive body iron accumulation. Therefore, early detection of tissue iron accumulation is mandatory for effective treatment. Besides serum ferritin (SF) as the traditional blood parameter indicating iron overload, the assessment of body iron stores by non-invasive magnetic resonance imaging (MRI) using R2- (T2) or R2*- (T2*) relaxometry is established in clinical routine. Especially the comparison of tissue iron burden and iron loading patterns is a current field of research in iron overload.Although the pancreas seems to play a major role in the endocrinological pathology of patients with siderosis, there are only few studies analyzing pancreatic iron content referring to the head, body and tail region of the pancreas. MethodA total of 69 patients (age 9 - 78 years, 31 females) with ß-Thalassemia major (TM: n = 42; 16 splenectomized), Diamond-Blackfan anemia (DBA: n = 7; 1 splenectomized), hereditary hemochromatosis (HHC: n = 11) and iron overload from chronic blood transfusions (n = 9; sideroblastic anemia, aplastic anemia, myelodysplastic syndrome, leukemia post bone marrow transplantation) were scanned between 2007 and 2012 as part of their regular heart and liver iron monitoring by MRI, respectively. 10 healthy subjects (3 females, age 23 - 68 years), voluntarily served as controls.The study was approved by the local ethics committee and all subjects gave their written informed consent.For measuring pancreatic R2*, a stack of 4-8 of slices (thickness = 5.5 mm, no gap, inplane resolution 1.25x1.25 mm2) was selected, covering the whole pancreas.Pancreatic signal intensities were averaged from three different ROIs positioned in the tail, body and head of the pancreas with sufficient distance to the gland boundaries and excluding vascular structures. Only clearly identified and demarcated pancreas tissue was considered.Since fat infiltration is a common problem in the pancreas, especially with phase dependent GRE times, we applied a water/fat separation technique to the in-phase and out-of-phase signal intensities as described by Wehrli et al. ResultsFor patients, the median hepatic R2* rate, pancreatic R2* rate and ferritin level were 261 s-1 (range 42 - 2326 s-1), 130 s-1 (range 23 – 1192 s-1) and 1445 µg/ml (range 62 – 21557 µg/ml), respectively.In 70% of all patients, fatty infiltration of the pancreas was above the range of controls (> 10%), with highest apparent fat content (aFC) in the pancreas of TM patients, especially, in TM patients with diabetes mellitus (median aFC = 29.1%). The highest aFC was found in the pancreatic tail (P = 0.2). Fat infiltration correlated with pancreatic R2* (rS = 0.67, P < 10-4). ConclusionWe compared R2* rates in the different pancreatic regions involving patient groups of different iron loading diseases. Patients showed significantly higher pancreatic R2* rates and apparent fat contents than controls. The pancreas tail revealed the highest R2* rates and fat contents so we hypothesize that iron uploading initially occurs in the pancreas tail, especially in TM patients. Fatty replacement and degeneration of the pancreas seems to be an important risk factor on top of pancreatic iron burden for the development of diabetes and should be further investigated in longitudinal studies. Disclosures:No relevant conflicts of interest to declare.

Monitoring iron therapy in chronic heart failure

This editorial refers to ‘The effect of intravenous ferriccarboxymaltoseonredcelldistributionwidth:asubanalysisof the FAIR-HF study,’ by E.M. Van Craenenbroeck et al.,published in this issue on pages 756–762.Iron deficiency has recently been identified as an important patho-genic factor affecting the severity and progression of chronic heartfailure(CHF).

Paraoxonase-1 status in patients with hereditary hemochromatosis

Hereditary hemochromatosis (HH) is characterized by accumulation of iron, oxidative stress, inflammation, and fibrogenesis in liver tissue. In this setting, research on the protection afforded by intracellular antioxidants is of clinical relevance. Paraoxonase-1 (PON1) is an enzyme that degrades lipid peroxides. This study investigates the alterations in serum PON1 status, PON1 gene polymorphisms, and PON1 hepatic expression in patients with HH. We performed a case-control study in 77 patients with HH (80.5% men, 22-70 years of age) and 408 healthy individuals (43.1% men, 26-74 years of age). Serum PON1 activities against different substrates and PON1192 and PON155 polymorphisms were analyzed. PON1 protein expression was investigated in 20 liver biopsies. HH patients had significantly lower serum PON1 activity, which was inversely correlated with ferritin (marker of iron stores) and serum 8-isoprostane concentrations (index of oxidative stress). PON1 protein expression in liver tissue was higher in patients and showed stronger staining in hepatocytes surrounding the areas of inflammation. Our study provides preliminary evidence that PON1 may play a role in protecting against iron-induced oxidative stress in hereditary hemochromatosis.

Abstract 5313: The potential role of cellular iron in head and neck squamous cell carcinoma.

Abstract Introduction. Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Half of the patients present with advanced disease, which despite aggressive treatments, achieves five-year survival rates of only 50%, underscoring a need to better understand the biology of this disease. One approach would be to examine the role of cellular iron in HNSCC. We are interested in the role of iron as a result of: (1) A previous study in our lab in which uroporphyrinogen decarboxylase was identified as a radiosensitizing target for HNSCC. The radiosentization was due to alterations in iron homeostasis which elevated reactive oxygen species (ROS) and enhance tumor oxidative stress and cytotoxicity. (2) The requirement of iron in a rate limiting step with ribonucleotide reductase for DNA synthesis, and hence cell proliferation. (3) The deregulation of iron in many cancers. Experimental design. A list of proteins involved in iron homeostasis was generate from the literature and evaluated using qRT-PCR in 3 HNSCC cells (FaDu, UTSCC 42a, UTSCC 8) compare to a Normal Oral Epithelial (NOE) cell line. The most highly over expressed iron protein across all cell lines compared to the NOE was hemochromatosis (HFE), thus was selected for further evaluation. Knockdown of HFE was achieved using a siRNA based approach and cellular effects were determined using MTS, clonogenic, BRDU and flow cytometry assays with or without 4 Gy of radiation. Iron rescue experiments where preformed using Ferric ammonium citrate (FACs). Iron chelation was accomplished in HNSCC cells lines using ciclopirox olamine (CPX), a clinical approved iron chelating chemotherapeutic. Results. HFE was selected for further evaluation based on the expression in HNSCC cell lines versus the NOE cell line. Mutations in HFE are linked to the genetic condition hemochromatosis, which is characterized by elevated hepcidin levels and iron accumulation in peripheral tissues. Cell proliferation assays (MTS, clonogenic, BRDU assay) after HFE knockdown with or without RT in HNSCC cells demonstrated a significant decrease in proliferation across all cancer cells with negligible effects on NOE cells. Furthermore, we observed a significant decrease in the Labile iron pool and cellular ROS levels, following HFE knockdown. Re-introduction of iron into the cell after HFE knockdown rescued our phenotype, suggesting that this process is indeed mediated by cellular iron levels. Next, we treated HNSCC cell lines CPX and observed a significant decrease in cell viability compared to control treated cells. Conclusion. HFE appears to be an important protein in controlling cellular iron. HFE knockdown resulted in a reduction in cellular iron which decreases the amount of iron available for DNA synthesis and hence cell proliferation. Therefore, elevated cellular iron appears to be an important factor for the progression of HNSCC, thus iron chelation strategies may valuable in the context of this disease. Citation Format: Michelle Lenarduzzi, Angela Hui, Winnie Yue, Justin Williams, Fei Fei Liu. The potential role of cellular iron in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5313. doi:10.1158/1538-7445.AM2013-5313

The Molecular and Cellular Basis of Iron Toxicity in Iron Overload (IO) Disorders. Diagnostic and Therapeutic Approaches

Abnormal iron accumulation in human tissues and oxidative damage are emerging issues in the medical field (1,2) [...]

Ecocardiografia de pacientes talassêmicos sem insuficiência cardíaca em tratamento com transfusões sanguíneas e quelação

Patients with thalassemia major present chronic hemolysis and require regular blood transfusions which may cause iron overload cardiomyopathy and chronic heart failure. Hemochromatosis is characterized by excessive iron accumulation in tissues, and heart involvement is the main cause of death in patients with thalassemia. The aim of this study was to evaluate cardiac structure and function by conventional Doppler echocardiography and tissue Doppler imaging in patients with TM and no clinical evidence of heart failure. This is a prospective observational study including 18 patients with thalassemia major (TM) receiving regular blood transfusion. To separately evaluate anemia and blood transfusion effects, two gender, age, weight, and height-matched control groups were included: one with healthy individuals (Healthy, n=18) and one with iron deficient anemia patients (Anemia, n=18). Statistical analysis was performed using ANOVA followed by Tukey's test or Kruskal-Wallis's and Dunn's test. The following echocardiographic variables presented significantly higher values in TM than the Anemia and Healthy groups: left atrium volume index (Healthy: 16.4±6.08; Anemia: 17.9±7.02; TM: 24.1±8.30 cm³/m²); mitral septal E/Em ratio (Healthy: 6.55±1.60; Anemia: 6.74±0.74; TM: 8.10±1.31); and duration of reverse pulmonary vein flow [Healthy: 74.0 (59.0-74.0); Anemia: 70.5 (67.0-74.0); TM: 111 (87.0-120) ms]. The mitral E/A ratio was higher in TM than Anemia (Healthy: 1.80±0.40; Anemia: 1.80±0.24; TM: 2.03±0.34). No differences were found in left ventricular structures and systolic function indexes. Conventional Doppler echocardiography and tissue Doppler allow changes in left ventricular diastolic function to be identified in asymptomatic patients with thalassemia major.

The relation of fragmented QRS with tissue Doppler derived parameters in patients with b-thalassaemia major

The most important complication encountered in patients with b-thalassaemia major is degenerative fibrosis developing as a result of iron accumulation in myocardial tissue. Dysfunction pursues this accumulation. Recently, presence of fragmented QRS (fQRS) in ECG has been regarded as a predictor of myocardial fibrosis. We aimed in our study to investigate the frequency with which fQRS develops in patients with b-thalassaemia major and to disclose the correlation between fQRS frequency and Doppler-derived indices. The patients with b-thalassaemia major (n=66; mean age: 23±6 years) and healthy controls (n=30; mean age: 23±4 years) were included. fQRS pattern was described as presence of RSR' manifested as existence of additional R wave and notching in either R or S waves in ECG recordings. 2D, M-mode, conventional Doppler, tissue Doppler echocardiography parameters were assessed. Mean serum ferritin levels over past 5 years were also calculated. When compared to those in control group, fQRS was more frequent in b-thalassaemia major group, indicating statistical significance (p = 0.001). While E/Em and ferritin level exhibited statistically significant increase in thalassaemia patients with fQRS (p < 0.05), the mean Em and Sm values were found to be significantly low (p < 0.05). fQRS was frequently observed in the patients with b-thalassaemia major, which was of statistical significance. Tissue Doppler-derived diastolic and systolic indices in thalassaemia cases with fQRS showed statistically significant impairment compared to those without fQRS. In conclusion, fQRS may represent a novel noninvasive marker for cardiac involvement in patients with b-thalassaemia major.

Metalloreductase Steap3 coordinates the regulation of iron homeostasis and inflammatory responses

Iron and its homeostasis are intimately related to inflammatory responses, but the underlying molecular mechanisms are poorly understood. We investigated the role of Steap3 in regulating iron homeostasis in macrophages, and the effects of Steap3 depletion on host inflammatory responses. We analyzed bone marrow-derived macrophages and primary cultured hepatocytes from Steap3(-/-) mouse models to investigate the roles of Steap3 in coordinately regulating iron homeostasis and inflammatory responses. First, we examined iron distribution and iron status in cells deficient in Steap3, as well as the requirement for the Steap3 gene during inflammatory responses. Secondly, we analyzed the regulation of Steap3 expression by inflammatory stimuli and thus, the influence of these stimuli on iron distribution and homeostasis. We found that Steap3 mRNA was expressed at high levels in macrophages and hepatocytes. Steap3 deficiency led to impaired iron homeostasis, causing abnormal iron distribution and a decreased availability of cytosolic iron in macrophages. Among STEAP family members, Steap3 mRNA was uniquely down-regulated in macrophages stimulated by lipopolysaccharides. To determine whether Steap3 regulated iron homeostasis during inflammatory stress, we treated Steap3(-/-) mice with lipopolysaccharide, which produced greater iron accumulation in the vital tissues of these mice compared to in the tissues of wild-type controls. Furthermore, Steap3 depletion led to impaired induction of interferon-β, monocyte chemoattractant protein-5, and interferon induced protein-10 in macrophages via the TLR4-mediated signaling pathway. Steap3 is important in regulating both iron homeostasis and TLR4-mediated inflammatory responses in macrophages. Steap3 deficiency causes abnormal iron status and homeostasis, which leads to impaired TLR4-mediated inflammatory responses in macrophages. Following inflammatory stimuli, Steap3 depletion causes dysregulated iron sequestration and distribution. Our results provide important insights into the function of Steap3 as a coordinate regulator of both iron homeostasis and innate immunity.

Haemochromatosis in a Brazilian tapir (Tapirus terrestris) in an Australian zoo

A 23-year-old Brazilian, or lowland, tapir with a 6-month history of loss of body condition developed clinical signs and laboratory findings consistent with liver failure. The animal was euthanased and a diagnosis of hepatic haemochromatosis was made based on histopathology. Two other healthy tapirs in the same collection had chronically elevated serum and tissue iron concentrations. The excessive accumulation of iron in tissues with resultant tissue damage (i.e. haemochromatosis) has been reported in a range of captive species. This and other reported cases of haemochromatosis in the Brazilian tapir would suggest that this condition is an important consideration in the management of this species in zoos. Further research into the endogenous regulation of iron metabolism, especially the role of hepcidin, in tapirs and other species at risk of iron storage disorders may be helpful in the prevention of this condition.

Tracking iron in multiple sclerosis: a combined imaging and histopathological study at 7 Tesla

Previous authors have shown that the transverse relaxivity R(2)* and frequency shifts that characterize gradient echo signal decay in magnetic resonance imaging are closely associated with the distribution of iron and myelin in the brain's white matter. In multiple sclerosis, iron accumulation in brain tissue may reflect a multiplicity of pathological processes. Hence, iron may have the unique potential to serve as an in vivo magnetic resonance imaging tracer of disease pathology. To investigate the ability of iron in tracking multiple sclerosis-induced pathology by magnetic resonance imaging, we performed qualitative histopathological analysis of white matter lesions and normal-appearing white matter regions with variable appearance on gradient echo magnetic resonance imaging at 7 Tesla. The samples used for this study derive from two patients with multiple sclerosis and one non-multiple sclerosis donor. Magnetic resonance images were acquired using a whole body 7 Tesla magnetic resonance imaging scanner equipped with a 24-channel receive-only array designed for tissue imaging. A 3D multi-gradient echo sequence was obtained and quantitative R(2)* and phase maps were reconstructed. Immunohistochemical stainings for myelin and oligodendrocytes, microglia and macrophages, ferritin and ferritin light polypeptide were performed on 3- to 5-µm thick paraffin sections. Iron was detected with Perl's staining and 3,3'-diaminobenzidine-tetrahydrochloride enhanced Turnbull blue staining. In multiple sclerosis tissue, iron presence invariably matched with an increase in R(2)*. Conversely, R(2)* increase was not always associated with the presence of iron on histochemical staining. We interpret this finding as the effect of embedding, sectioning and staining procedures. These processes likely affected the histopathological analysis results but not the magnetic resonance imaging that was obtained before tissue manipulations. Several cellular sources of iron were identified. These sources included oligodendrocytes in normal-appearing white matter and activated macrophages/microglia at the edges of white matter lesions. Additionally, in white matter lesions, iron precipitation in aggregates typical of microbleeds was shown by the Perl's staining. Our combined imaging and pathological study shows that multi-gradient echo magnetic resonance imaging is a sensitive technique for the identification of iron in the brain tissue of patients with multiple sclerosis. However, magnetic resonance imaging-identified iron does not necessarily reflect pathology and may also be seen in apparently normal tissue. Iron identification by multi-gradient echo magnetic resonance imaging in diseased tissues can shed light on the pathological processes when coupled with topographical information and patient disease history.

Age-related Accumulation of Non-heme Ferric and Ferrous Iron in Mouse Ovarian Stroma Visualized by Sensitive Non-heme Iron Histochemistry

Sensitive non-heme iron histochemistry--namely, the perfusion-Perls method and perfusion-Turnbull method--was applied to study the distribution and age-related accumulation of non-heme ferric iron and ferrous iron in mouse ovary. Light and electron microscopic studies revealed that non-heme ferric iron is distributed predominantly in stromal tissue, especially in macrophages. By contrast, the distribution of non-heme ferrous iron was restricted to a few ovoid macrophages. Aged ovaries exhibited remarkable non-heme iron accumulation in all stromal cells. In particular, non-heme ferrous iron level was increased in stromal tissue, suggestive of increased levels of redox-active iron, which can promote oxidative stress. Moreover, intense localization of both non-heme ferric and ferrous iron was observed in aggregated large stromal cells that were then characterized as ceroid-laden enlarged macrophages with frothy cytoplasm. Intraperitoneal iron overload in adult mice resulted in non-heme iron deposition in the entire stroma and generation of enlarged macrophages, suggesting that excessive iron accumulation induced macrophage morphological changes. The data indicated that non-heme iron accumulation in ovarian stromal tissue may be related to aging of the ovary due to increasing oxidative stress.

Target TMPRSS6 for the Treatment of Hereditary Hemochromatosis

Abstract 1047Hereditary hemochromatosis (HH) is a genetic disorder in which hyperabsorption of dietary iron leads to accumulation of iron in multiple tissues including liver and heart. A common clinical manifestation in HH patients is cirrhosis and hepatocellular carcinoma as a result of iron-mediated injury in liver. The most prevalent genetic defect for HH is the failure to up-regulate hepcidin, a peptide hormone that inhibits the absorption of iron in duodenum and the release of iron from intracellular iron storage such as macrophages. Mutations in a number of genes have been identified as the cause for HH, including hepcidin itself. However, the most common mutation is C282Y mutation in HFE, which is a positive regulator for hepcidin expression. C282Y mutation represents about 85% of the HH population. HFE C282Y HH is an autosomal recessive disease with a ∼50% penetrance. Currently, the only treatment available for iron overload is phlebotomy which will continue throughout the patient’s life.Hepcidin is mainly expressed and secreted by the liver and its expression is regulated predominantly at the transcription level. TMPRSS6, a transmembrane serine protease mutated in iron-refractory, iron-deficient anemia, is a major suppressor for hepcidin expression. It’s been demonstrated that hepcidin expression is significantly elevated in Tmprss6−/− mice and reduction of TMPRSS6 in Hfe−/− mice could ameliorate the iron overload phenotype (Du et al. Science 2008; Folgueras et al. Blood 2008; Finberg KE et al., Blood, 2011).Using second generation antisense technology, we identified antisense oligonucleotides (ASOs) targeting mouse TMPRSS6 for the treatment of HH. These compounds were first identified through in vitro screens in mouse primary hepatocytes. After 4 weeks of treatment in C57BL/6 mice on normal chow, we observed an 80% to 90% reduction of liver TMPRSS6 mRNA with a subsequent 2–3 fold induction of liver hepcidin mRNA. Serum iron and transferrin saturation levels were reduced by ∼50%. These ASOs are currently being evaluated in a diet-induced iron overload model and an Hfe−/− iron overload model. Our preliminary results demonstrate that targeting TMPRSS6 is a viable approach for the treatment of hereditary hemochromatosis and possibly other iron-loading diseases associated with suppressed hepcidin levels. Disclosures:Booten:Isis Pharmaceuticals: Employment. Knox:Isis Pharmaceuticals: Summer Intern. Alvarado:Isis Pharmaceuticals: Employment. Guo:Isis Pharmaceuticals: Employment. Monia:Isis Pharmaceuticals: Employment.

Transcranial sonography in pantothenate kinase-associated neurodegeneration

After it was reported that increased tissue iron concentrations were associated with increased echogenicity of the substantia nigra (SN) obtained with transcranial sonography (TCS) in animal and postmortem studies, our goal was to use this method in a disorder characterized with iron accumulation in human brain tissue. Therefore, magnetic resonance imaging (MRI) and TCS were conducted in 5 unrelated patients with pantothenate kinase-associated neurodegeneration (PKAN), caused by PANK2 mutations. All patients had an eye of the tiger sign. Hypointense lesions on the T2-weighted MRI images were restricted to the globus pallidus (GP) and SN. TCS also revealed bilateral hyperechogenicity restricted to the LN and SN, with normal DTV values. Both TCS and MRI studies in PKAN patients are in accordance with the pathological findings that accumulation of iron, even in advanced cases, is restricted to the GP and SN, suggesting selective involvement of these structures.

The Role of Catalytic Iron in Acute Kidney Injury

The pathologic effects of iron accumulation in tissue in iron-overload states, such as are described in patients with thalassemia, are widely known. What is new in the field is the recognition that iron plays an important role in the pathophysiology of tissue injury in the absence of systemic iron

The Investigation of Gingival Iron Accumulation in Thalassemia Major Patients

Thalassemia major (TM) is an autosomal-recessive genetic blood disorder. Regular blood transfusions to improve chronic anemia caused by ineffective erythropoiesis and hemolysis lead to iron overload in many organs in TM patients. The aim of this study was to investigate the periodontal status and the iron accumulation in gingival tissues of TM patients and assess whether iron deposition in gingival biopsies could be an alternative method for the diagnosis of body iron overload in TM patients. This study was conducted on 22 TM patients and 20 healthy matched controls. Plaque index, gingival index, and probing pocket depth were measured and gingival biopsies were obtained in all subjects. Venous blood samplings and liver biopsies were carried out only in patients with thalassemia. Gingiva and liver tissue samples were evaluated histopathologically for inflammation, iron accumulation, and fibrosis. There was no difference between the groups regarding periodontal health, and all patients had mild gingivitis. Gingival iron accumulation was observed only in the TM group. The iron accumulation was detected in the liver of all the patients with thalassemia. The gingival iron accumulation was correlated with neither serum ferritin levels nor hepatic iron accumulations. The periodontal tissues are affected by iron accumulation as well as hepatic, cardiac, and endocrine tissues in TM patients. Further studies investigating the usage of the gingival biopsy for prediagnosis of body iron overload in TM patients are needed.

Sequence Variations in Mitochondrial Ferritin: Distribution in Healthy Controls and Different Types of Patients

The storage of iron in the cells is mainly accomplished by cytosolic ferritins. The perturbation of ferritin function may result in accumulation of excess iron in cells and tissues and increased oxidative stress, common features of different genetic and acquired disorders. Mutations in L-ferritin have been associated with neuroferritinopathy, a rare and severe movement disorder with abnormal brain iron storage. Recently, a novel form of ferritin has been discovered, which localizes in the mitochondrial matrix and plays an important role in iron homeostasis in these organelles. The possible association of sequence variations in the mitochondrial ferritin (FtMt) gene with disorders with aberrant iron distribution has not been investigated yet. We set up a denaturing high-performance liquid chromatography (DHPLC)-based screening for FtMt and analyzed the genomic DNA of patients with myelodysplastic syndromes (# 63) or with Parkinson's disease (# 332) and other movement disorders such as pantothenate kinase-associated neurodegeneration (# 7), restless legs syndrome (# 23), and suspected neuroferritinopathy (# 7) and of control subjects (# 342). We detected eight different types of substitution, all at the heterozygous state. Six of them caused amino acid changes, but none of them was predicted to drastically perturb FtMt structure and/or function. The c + 134C > A (P45H) variation, which was the most common (# 28), was less represented in the Parkinson's population, although not significantly (p = 0.07). The analysis suggests that sequence variations in the coding region of FtMt are not involved in the development of myelodysplastic syndromes and Parkinson's disease.

Adiponectin-Mediated Heme Oxygenase-1 Induction Protects Against Iron-Induced Liver Injury via a PPARα-Dependent Mechanism

Protective effects of adiponectin (APN; an adipocytokine) were shown against various oxidative challenges; however, its therapeutic implications and the mechanisms underlying hepatic iron overload remain unclear. Herein, we show that the deleterious effects of iron dextran on liver function and iron deposition were significantly reversed by adiponectin gene therapy, which was accompanied by AMP-activated protein kinase (AMPK) phosphorylation and heme oxygenase (HO)-1 induction. Furthermore, AMPK-mediated peroxisome proliferator-activated receptor-α (PPARα) activation by APN was ascribable to HO-1 induction. Additionally, we revealed direct transcriptional regulation of HO-1 by the binding of PPARα to a PPAR-responsive element (PPRE) by various experimental assessments. Interestingly, overexpression of HO-1 in hepatocytes mimicked the protective effect of APN in attenuating iron-mediated injury, whereas it was abolished by SnPP and small interfering HO-1. Furthermore, bilirubin, the end-product of the HO-1 reaction, but not CO, protected hepatocytes from iron dextran-mediated caspase activation. Herein, we demonstrate a novel functional PPRE in the promoter regions of HO-1, and APN-mediated HO-1 induction elicited an antiapoptotic effect and a decrease in iron deposition in hepatocytes subjected to iron challenge.

Transferrin Receptor 1: A Ferritin Receptor as Well?

Transferrin Receptor 1: A Ferritin Receptor as Well?

Elevated Systemic Hepcidin and Iron Depletion in Obese Premenopausal Females

Hepcidin, the body's main regulator of systemic iron homeostasis, is upregulated in response to inflammation and is thought to play a role in the manifestation of iron deficiency (ID) observed in obese populations. We determined systemic hepcidin levels and its association with body mass, inflammation, erythropoiesis, and iron status in premenopausal obese and nonobese women (n = 20/group) matched for hemoglobin (Hb). The obese participants also had liver and abdominal visceral and subcutaneous adipose tissue assessed for tissue iron accumulation and hepcidin mRNA expression. Despite similar Hb levels, the obese women had significantly higher serum hepcidin (88.02 vs. 9.70 ng/ml; P < 0.0001) and serum transferrin receptor (sTfR) (P = 0.001) compared to nonobese. In the obese women hepcidin was not correlated with serum iron (r = -0.02), transferrin saturation (Tsat) (r = 0.17) or sTfR (r = -0.12); in the nonobese it was significantly positively correlated with Tsat (r = 0.70) and serum iron (r = 0.58), and inversely with sTfR (r = -0.63). Detectable iron accumulation in the liver and abdominal adipose tissue of the obese women was minimal. Liver hepcidin mRNA expression was ~700 times greater than adipose tissue production and highly correlated with circulating hepcidin levels (r = 0.61). Serum hepcidin is elevated in obese women despite iron depletion, suggesting that it is responding to inflammation rather than iron status. The source of excess hepcidin appears to be the liver and not adipose tissue. The ID of obesity is predominantly a condition of a true body iron deficit rather than maldistribution of iron due to inflammation. However, these findings suggest inflammation may perpetuate this condition by hepcidin-mediated inhibition of dietary iron absorption.