Pathogenesis Of Iron Overload Research Articles

Genetic Correlation of HBB, HFE and HAMP Genes to Endocrinal Complications in Egyptian Beta Thalassemia Major Patients.

Iron loading is regarded as the primary cause of endocrine abnormalities in thalassemia major patients. Thus, the purpose of the current research was to explore the impact of thalassemia genotypes, hepcidin antimicrobial peptide (HAMP) and hereditary hemochromatosis (HFE) gene variants, and hepcidin expression on serum ferritin and endocrinal complications in thalassemia patients. The study comprised fifty beta-thalassemia cases and fifty age- and sex-matched controls. Genotyping of the Beta-globin gene (HBB), HAMP, and exon 2 of the HFE gene was performed using Sanger sequencing. C282Y (c.845G > A) variant of the HFE gene was determined by PCR-RFLP. Hepcidin mRNA expression was assessed by qRT-PCR. Biochemical and hormonal studies were done for all patients. Hypogonadism and short stature were found in 56% and 20% of the investigated cases, respectively. Molecular studies reported a statistically higher frequency of the HAMP variant c.-582A > G in thalassemic patients than controls. Significant downregulation of hepcidin expression was found in cases compared to healthy subjects that was significantly associated with short stature. Considering the thalassemia alleles, the IVSI.1G > A (β0) allele was statistically related to hypogonadism. Our results proposed that thalassemia genotypes and downregulated hepcidin expression were the potential risk factors for endocrinopathies in our cases. We also demonstrated an increased incidence of the HAMP promoter variant c.-582A > G that might have a role in the pathogenesis of iron overload in thalassemic cases. Significant downregulation of hepcidin expression, that contributes to increased iron burden, could be used as a future therapeutic target in these patients.

Serum erythroferrone diagnostic value in patients with beta-thalassemia with iron overload

Introduction Patients with beta-thalassemia experience a major complication besides their anemia, which is the iron overload and its complications up to death. Erythroferrone (ERFE) and hepcidin are the major controlling factors for serum iron level, being inversely related to each other. Patients with iron overload are thought to have low serum hepcidin and high serum ERFE levels. So, serum ERFE is postulated to be involved in the pathogenesis of iron overload in patients with β-thalassemia. A cross-sectional study has been conducted, including 112 participants: 80 patients with β-thalassemia and 32 healthy age-matched and sex-matched controls. Serum ERFE, ferritin, and hepcidin were measured by enzyme-linked immunosorbent assay and compared among patients with β-thalassemia and healthy controls. Patients had significantly higher serum ferritin, ERFE, as well as lower serum hepcidin levels as compared with healthy age-matched and sex-matched controls, with P values less than 0.001, less than 0.001, and 0.045, respectively. Serum ERFE may serve as an important marker for iron overload and may represent a future possible therapeutic target using anti-ERFE to control iron overload.

The rs4808793 polymorphism of GDF-15 associates with significantly elevated ferritin in both thalassemia major and thalassemia intermedia

Background: Previous studies have proposed the rs4808793 polymorphism of the GDF-15 as a potent inducer of hypertension, cardiovascular disease, and renal failure. The current study was performed to investigate the role of rs4808793 polymorphism in the pathogenesis of iron overload in patients suffering from major or intermedia β-thalassemia. Materials and Methods: The study included 69 major thalassemia patients and 25 intermedia thalassemia patients as the control group. The study was conducted on 69 major thalassemia and 25 intermedia thalassemia patients who referred to Baqa'i Hospital 2 in Ahvaz, Iran. Five milliliter blood was collected and DNA was extracted. After DNA amplification by the use of polymerase chain reaction, the rs4808793 polymorphism was detected by AlwNI restriction enzyme application and restriction fragment length polymorphism. Results: Mean serum ferritin in patients with β-thalassemia major (3490.41 ± 169.22 ng/ml) was significantly higher than those with thalassemia intermedia (677.16 ± 388.80) (P 0.05). Both cases and controls with rs4808793 polymorphism showed significantly elevated serum ferritin concentrations compared to patients without mutations (P

Assessment of Pancreatic Iron Overload in Transfusion Dependent Thalassemic Patients

Advances in the management of transfusion dependent thalassemic patients have improved the survival of these patients. The most important consequence of repeated and frequent transfusions is iron accumulation in vital organs. The magnetic resonance imaging (MRI) is a non-invasive and valid technique for the estimation of iron stores. Despite multiple studies about cardiac and liver MRI T2*, there is limited experience about pancreatic MRI. Although there is a weak correlation between hepatic and pancreatic siderosis, MRI assessment of iron deposition in the pancreas can reduce cardiac morbidity. Pancreatic siderosis may be a predictor for the development of glucose dysregulation. Pancreatic R2* > 100 Hz is a risk factor for glucose intolerance or even overt diabetes. Splenectomy can accentuate the pancreatic iron overload. Early intensive chelation therapy in thalassemia patients can reverse glucose metabolism impairment. In this review, the MRI assessment of pancreatic iron overload in transfusion dependent thalassemia, the correlation between pancreas with liver and myocardial hemosiderosis and the importance of pancreatic iron overload in pathogenesis of diabetes mellitus in these patients were discussed.

The Relevancy of Data Regarding the Metabolism of Iron to Our Understanding of Deregulated Mechanisms in ALS; Hypotheses and Pitfalls

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the loss of motor neurons. Its etiology remains unknown, but several pathophysiological mechanisms are beginning to explain motor neuronal death, as well as oxidative stress. Iron accumulation has been observed in both sporadic and familial forms of ALS, including mouse models. Therefore, the dysregulation of iron metabolism could play a role in the pathological oxidative stress in ALS. Several studies have been undertaken to describe iron-related metabolic markers, in most cases focusing on metabolites in the bloodstream due to few available data in the central nervous system. Reports of accumulation of iron, high serum ferritin, and low serum transferrin levels in ALS patients have encouraged researchers to consider dysregulated iron metabolism as an integral part of ALS pathophysiology. However, it appears complicated to suggest a general mechanism due to the diversity of models and iron markers studied, including the lack of consensus among all of the studies. Regarding clinical study reports, most of them do not take into account confusion biases such as inflammation, renal dysfunction, and nutritional status. Furthermore, the iron regulatory pathways, particularly involving hepcidin, have not been thoroughly explored yet within the pathogenesis of iron overload in ALS. In this sense, it is also essential to explore the relation between iron overload and other ALS-related events, such as neuro-inflammation, protein aggregation, and iron-driven cell death, termed ferroptosis. In this review, we point out limits of the designs of certain studies that may prevent the understanding of the role of iron in ALS and discuss the relevance of the published data regarding the pathogenic impact of iron metabolism deregulation in this disease and the therapeutics targeting this pathway.

KELEBIHAN ZAT BESI SEKUNDER BERKAITAN DENGAN SATURASI TRANSFERIN DAN FERITIN

Iron overload disorder is a condition due to an excessive rate of iron acquisition compared to the rate of body iron loss that happens constantly. The clinical manifestations vary depending on the location of the damaged organs. Consequently, the symptoms of iron overload may mimic many diseases such as cirrhosis, diabetes mellitus, arthropathy, and skin pigmentation. The laboratory results which may point to iron overload are as follows: transferrin saturation >45%, serum ferritin level >300 ng/ml in men and >200 ng/ml in women. It is thus imperative that the molecular mechanism of iron metabolism and pathogenesis of iron overload are well understood in order to correct the interpretation of the laboratory results for iron overload. The standard management is blood removal by phlebotomy to maintain the level of the serum ferritin at 50 ng/mL in order to prevent irreversible hepatic cirrhosis

New Insights on Iron Study in Myelodysplasia

Objective: Hepcidin plays a pivotal role in iron homeostasis. It is predominantly produced by hepatocytes and inhibits iron release from macrophages and iron uptake by intestinal epithelial cells. Competitive ELISA is the current method of choice for the quantification of serum hepcidin because of its lower detection limit, low costs, and high throughput. This study aims to discuss the role of hepcidin in the pathogenesis of iron overload in recently diagnosed myelodysplasia (MDS) cases. Materials and Methods: The study included 21 recently diagnosed MDS patients and 13 healthy controls. Ferritin, hepcidin, and soluble transferrin receptor (sTFR) were measured in all subjects. Results: There were 7 cases of hypocellular MDS, 8 cases of refractory cytopenia with multilineage dysplasia, and 6 cases of refractory anemia with excess blasts. No difference was observed among the 3 MDS subtypes in terms of hepcidin, sTFR, and ferritin levels (p>0.05). Mean hepcidin levels in the MDS and control groups were 55.8±21.5 ng/mL and 19.9±2.6 ng/mL, respectively. Mean sTFR was 45.7±8.8 nmol/L in MDS patients and 31.1±5.6 nmol/L in the controls. Mean ferritin levels were significantly higher in MDS patients than in controls (539.14±83.5 ng/mL vs. 104.6±42.9 ng/mL, p<0.005). There was a statistically significant correlation between hepcidin and sTFR (r=0.45, p=0.039). No difference in hepcidin levels between males and females was observed, although it was lower in males in comparison to females (47.9±27.6 vs. 66.7±35.7, p>0.05). Conclusion: Hepcidin may not be the main cause of iron overload in MDS. Further studies are required to test failure of production or peripheral unresponsiveness to hepcidin in MDS cases.

Serum iron metabolism and erythropoiesis in patients with myelodysplastic syndrome not receiving RBC transfusions

Dysregulation of hepcidin, a key iron regulating hormone, is important in the pathogenesis of iron overload in patients with myelodysplatic syndrome (MDS). However, most studies of hepcidin levels are complicated by concomitant RBC transfusions. To evaluate the relationship between iron metabolism and erythropoiesis, we measured serum levels of hepcidin, growth-differentiation factor-15 (GDF15) and other markers of erythropoiesis in 107 subjects with MDS not receiving RBC transfusions. Patients with MDS had significantly higher levels of hepcidin than normals. However, their hepcidin-ferritin ratio was markedly decreased compared to normals (P<0.001) and varied substantially between MDS subtypes (P=0.011). GDF15 levels positively correlated with percent of bone marrow erythroblasts (P<0.001), soluble transferrin receptor (sTfR) (P=0.018), and also with transferrin saturation (ISAT) (P=0.038). The hepcidin-ferritin ratio negatively correlated with serum erythropoietin (EPO) levels (P<0.001), and also with GDF15 levels (P=0.014). Colony forming cells (CFC) were evaluated in 70 subjects. Those with serum ferritin (SF) levels <500 ng/ml had significantly more BFU-E than subjects with SF ≥ 500 ng/L (P=0.007), but numbers of granulocyte/macrophage-colony-forming cells (CFU-GM) were similar (P=0.190). Our data indicate serum hepcidin levels are inappropriately low in patients MDS not receiving RBC transfusions. GDF15 levels correlated with low hepcidin levels and may contribute to iron overload in this setting. Iron overload may in turn suppress erythropoiesis by imparing the proliferative capacity of the erythroid progenitor cells.

P1-61 Polymorphic variation in DNA methyltransferase genes in relation to birth weight, smoking and folate status

Since 1996, the identification of the HFE gene has enabled DNA testing for hereditary haemochromatosis (HH). The range of DNA testing available includes: (1) diagnostic, (2) predictive (also called presymptomatic testing) and (3) screening. Access to DNA testing has been facilitated by an Australian Medicare rebate, the first available for genetic disorders. Despite the availability of HFE DNA testing in HH, it remains necessary to interpret results in the context of the clinical picture. Traditional markers based on phenotype (transferrin saturation, ferritin and liver biopsy) are still required in some circumstances. We report our experience with HFE DNA testing using a semi-automated approach, which allows multiplexing for the two common mutations (C282Y and H63D). Screening a cohort of β-thalassaemia major and sickle cell anaemia patients of predominantly Mediterranean origin showed that these individuals do not have the common C282Y mutation. This excluded C282Y as a factor in the pathogenesis of iron overload in these haemoglobinopathies. It also showed that the C282Y mutation is of limited value when investigating HH in certain ethnic groups. An Australian family studied illustrated the relative contribution of C282Y and H63D in iron overload. A recently reported third mutation (S65C) in the HFE gene was detected in a low frequency in the populations tested.

Liver iron concentrations and urinary hepcidin in -thalassemia

Patients with beta-thalassemia, like those with genetic hemochromatosis, develop iron overload due to increased iron absorption, and their iron burden is further exacerbated by transfusion therapy. Hepcidin, a hepatic hormone, regulates systemic iron homeostasis by inhibiting the absorption of iron from the diet and the recycling of iron by macrophages. In turn, hepcidin release is increased by iron loading and inhibited by erythropoietic activity. Hepcidin deficiency is the cause of iron overload in most forms of hereditary hemochromatosis. We sought to determine hepcidin's role in the pathogenesis of iron overload in b-thalassemia. We assessed the degree of iron overload in thalassemia intermedia and major patients by measuring hepatic iron concentration in liver biopsy samples and serum ferritin, estimated erythropoietic drive by assaying soluble transferrin receptor and serum erythropoietin levels and correlated these with urinary hepcidin measurements. Urinary hepcidin levels in beta-thalassemia demonstrate severe hepcidin deficiency in thalassemia intermedia. There was a strong inverse relationship between urinary hepcidin levels and both erythropoietin and soluble transferrin receptor, markers of erythropoietic activity. In contrast, hepcidin levels were elevated in thalassemia major, presumably due to transfusions that reduce erythropoietic drive and deliver a large iron load. Despite similar liver iron concentrations in the two conditions, serum ferritin was much lower in thalassemia intermedia. In thalassemia intermedia, high erythropoietic drive causes severe hepcidin deficiency. The lack of hepcidin results in hyperabsorption of dietary iron, but also in iron depletion of macrophages, lowering their secretion of ferritin and, consequently, serum ferritin levels. In contrast, in thalassemia major, transfusions decrease erythropoietic drive and increase the iron load, resulting in relatively higher hepcidin levels. In the presence of higher hepcidin levels, dietary iron absorption is moderated and macrophages retain iron, contributing to higher serum ferritin. In the future, hepcidin measurements may allow a more accurate assessment of the degree of iron overload and the maldistribution of iron in thalassemia.

Hepcidin Expression in the Liver: Relatively Low Level in Patients with Chronic Hepatitis C

Patients with chronic hepatitis C frequently have serum and hepatic iron overload, but the mechanism is unknown. Recently identified hepcidin, exclusively synthesized in the liver, is thought to be a key regulator for iron homeostasis and is induced by infection and inflammation. This study was conducted to determine the hepatic hepcidin expression levels in patients with various liver diseases. We investigated hepcidin mRNA levels of liver samples by real-time detection-polymerase chain reaction; 56 were hepatitis C virus (HCV) positive, 34 were hepatitis B virus (HBV) positive, and 42 were negative for HCV and HBV (3 cases of auto-immune hepatitis, 7 alcoholic liver disease, 13 primary biliary cirrhosis, 9 nonalcoholic fatty liver disease, and 10 normal liver). We analyzed the relation of hepcidin to clinical, hematological, histological, and etiological findings. Hepcidin expression levels were strongly correlated with serum ferritin (P < 0.0001) and the degree of iron deposit in liver tissues (P < 0.0001). Hepcidin was also correlated with hematological parameters (vs. hemoglobin, P = 0.0073; vs. serum iron, P = 0.0012; vs. transferrin saturation, P < 0.0001) and transaminase levels (P = 0.0013). The hepcidin-to-ferritin ratio was significantly lower in HCV(+) patients than in HBV(+) patients (P = 0.0129) or control subjects (P = 0.0080). In conclusion, hepcidin expression levels in chronic liver diseases were strongly correlated with either the serum ferritin concentration or degree of iron deposits in the liver. When adjusted by either serum ferritin values or hepatic iron scores, hepcidin indices were significantly lower in HCV(+) patients than in HBV(+) patients, suggesting that hepcidin may play a pivotal role in the pathogenesis of iron overload in patients with chronic hepatitis C.

Deregulation of proteins involved in iron metabolism in hepcidin-deficient mice

AbstractEvidence is accumulating that hepcidin, a liver regulatory peptide, could be the common pathogenetic denominator of all forms of iron overload syndromes including HFE-related hemochromatosis, the most prevalent genetic disorder characterized by inappropriate iron absorption. To understand the mechanisms whereby hepcidin controls iron homeostasis in vivo, we have analyzed the level of iron-related proteins by Western blot and immunohistochemistry in hepcidin-deficient mice, a mouse model of severe hemochromatosis. These mice showed important increased levels of duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), and ferroportin compared with control mice. Interestingly, the level of ferroportin was coordinately up-regulated in the duodenum, the spleen, and the liver (predominantly in the Kupffer cells). Finally, we also evidenced a decrease of ceruloplasmin in the liver of hepcidin-deficient mice. We hypothesized that the deregulation of these proteins might be central in the pathogenesis of iron overload, providing key therapeutic targets for iron disorders. (Blood. 2005;105:4861-4864)

1060 Iron re-accumulation following phlebotomy: implications for the use and value of phlebotomy in the treatment of hereditary haemochromatosis

Since 1996, the identification of the HFE gene has enabled DNA testing for hereditary haemochromatosis (HH). The range of DNA testing available includes: (1) diagnostic, (2) predictive (also called presymptomatic testing) and (3) screening. Access to DNA testing has been facilitated by an Australian Medicare rebate, the first available for genetic disorders. Despite the availability of HFE DNA testing in HH, it remains necessary to interpret results in the context of the clinical picture. Traditional markers based on phenotype (transferrin saturation, ferritin and liver biopsy) are still required in some circumstances. We report our experience with HFE DNA testing using a semi-automated approach, which allows multiplexing for the two common mutations (C282Y and H63D). Screening a cohort of β-thalassaemia major and sickle cell anaemia patients of predominantly Mediterranean origin showed that these individuals do not have the common C282Y mutation. This excluded C282Y as a factor in the pathogenesis of iron overload in these haemoglobinopathies. It also showed that the C282Y mutation is of limited value when investigating HH in certain ethnic groups. An Australian family studied illustrated the relative contribution of C282Y and H63D in iron overload. A recently reported third mutation (S65C) in the HFE gene was detected in a low frequency in the populations tested.

Mutaciones en el gen HFE (C282Y, H63D, S65C) en pacientes alcohólicos con datos de sobrecarga de hierro

The pathogenesis of iron overload in alcoholic individuals is not fully elucidated. The frequency of mutations in hereditary hemochromatosis (HFE) is high in this population. Heterozygotes show data of iron overload similar to those in alcoholic individuals. To analyze whether iron excess among alcoholic individuals is associated with mutations in C282Y, H63D or S65C in the HFE gene. Patients and methods. Thirty-two active alcoholic individuals (29 males and 3 females, age range 30-67 years) with data of iron overload (increased serum ferritin with or without saturation of increased transferrin) were studied. In all individuals, mutations C282Y, H63D and S65C were investigated. From 16 cases, liver histology was available. Data on iron overload were compared between patients with and without mutations. Twenty-two patients (68.8%) did not show any mutation, one (3.1%) was heterozygous for C282Y, three (9.4%) were homozygous for H63D, four (12.5%) were heterozygous for H63D, and two patients (6.3%) were heterozygous for C282Y/H63D. None of the patients was homozygous for C282Y or presented mutation in S65C. Transferrin saturation, serum ferritin and liver iron index were similar among with and without mutations. Three patients (9.3%) were diagnosed of hemochromatosis. One of them was homozygous for H63D, other patient was heterozygous for the combined C282Y/H63D, and in the remaining patient none of the mutations was found. In our setting, iron overload among alcoholic individuals seems to be independent of the presence of mutations C282Y, H63D and S65C in the HFE gene.

Increased hepatic iron and cirrhosis: No evidence for an adverse effect on patient outcome following liver transplantation

It has been suggested that preexisting severe hepatic iron overload may adversely affect outcome after liver transplantation. The pathogenesis of iron overload in cirrhosis in the absence of hemochromatosis gene ( HFE) mutations is poorly understood. The relationships between liver disease severity and etiology, degree of hepatic iron overload, and post-liver transplantation outcome were studied in 282 consecutive adult patients with cirrhosis. Thirty-seven percent of patients had stainable hepatic iron. Increased hepatic iron concentration was significantly associated with more severe liver disease ( P < .001), male sex ( P = .05), the presence of spur cell anemia ( P < .0001), and hepatocellular liver disease ( P < .0001). The HFE mutations were uncommon in patients with increased hepatic iron stores. Increased hepatic iron concentration was not associated with greater utilization of resources or a lower survival after liver transplantation. Child-Pugh score at the time of liver transplantation was the only independent variable affecting patient survival ( P = .0008). In summary, our data suggest that the severity of the liver disease rather than hepatic iron concentration is the most important determinant of outcome after liver transplantation and that, in general, increasing hepatic iron concentration in cirrhosis is a surrogate marker of the severity of the underlying liver disease. (Hepatology2000;32:1200-1207.)

DNA testing for haemochromatosis: diagnostic, predictive and screening implications

Since 1996, the identification of the HFE gene has enabled DNA testing for hereditary haemochromatosis (HH). The range of DNA testing available includes: (1) diagnostic, (2) predictive (also called presymptomatic testing) and (3) screening. Access to DNA testing has been facilitated by an Australian Medicare rebate, the first available for genetic disorders. Despite the availability of HFE DNA testing in HH, it remains necessary to interpret results in the context of the clinical picture. Traditional markers based on phenotype (transferrin ferritinsaturation, and liver biopsy) are still required in some circumstances. We report our experience with HFE DNA testing using a semi-automated approach, which allows multiplexing for the two common mutations (C282Y and H63D). Screening a cohort of beta-thalassaemia major and sickle cell anaemia patients of predominantly Mediterranean origin showed that these individuals do not have the common C282Y mutation. This excluded C282Y as a factor in the pathogenesis of iron overload in these haemoglobinopathies. It also showed that the C282Y mutation is of limited value when investigating HH in certain ethnic groups. An Australian family studied illustrated the relative contribution of C282Y and H63D in iron overload. A recently reported third mutation (S65C) in the HFE gene was detected in a low frequency in the populations tested.