The pathology of hepatic iron overload: a free radical--mediated process?

Relationship of TNFα-238 G/A (rs 361525) genotypes with TNFα gene expression in liver and pancreas disorders in sample of beta thalassemia major adult Iraqi patients

BACKGROUND

Tumor necrosis factor-α (TNFα) is a crucial physiologic regulator of immune responses, and several disorders have been associated with its dysregulation.

OBJECTIVE

This study aimed to understand TNFα gene expression in adult patients with liver and pancreas disorders and examine the impact of TNFα-238 genotypes on this population.

METHODS

At the Ibn Al-Baladi Hospital in Baghdad, blood samples were collected from forty patients who were diagnosed with beta thalassemia together with pancreatic disease, forty patients who were diagnosed with thalassemia together with liver disorder, and forty patients who were diagnosed with thalassemia without pancreas or liver disorder. For the purpose of establishing a control group, forty samples were collected from persons who were of the same age and gender and seemed to be in good health. All of these individuals were deemed to be older than 18 years old. Through the utilization of real-time polymerase chain reaction (PCR), the level of TNF-α gene expression was investigated and assessed. The T-ARMS-PCR method was performed for detection and genotyping of TNFα-238 in thalassemia patients and healthy control samples.

RESULTS

The result showed that TNF α gene expression assessment showed that group B (thalassemia patients with liver disorder) had higher folding than other groups while the lowest gene expression was in group D (as control group). Furthermore, the relationship between TNFα gene expressions folding with TNFα-238 genotypes in beta thalassemia major patients, discovered a considerable increase at GA genotype patients in TNFα gene expression level, followed by AA genotype compared to the GG genotype. Furthermore, the results of the current study showed an association between the presence of the mutant (A) allele whether heterozygous (GA) and homozygous (AA) with the TNF-α gene expression in thalassemia patients with liver and pancreatic disorders.

CONCLUSION

Based on the results, it can be concluded that there is a relationship between the presence of the mutant (A) allele, whether heterozygous (GA) or homozygous (AA) of TNF-α 238, and TNF-α gene expression in liver and pancreatic diseases as well as in patients with thalassemia.

Inhibition of free heme-catalyzed Fenton-like reaction prevents non-alcoholic fatty liver disease by hepatocyte-targeted hydrogen delivery

The metabolic disorder of hepatocytes in non-alcoholic fatty liver disease (NAFLD) leads to the formation of an iron pool which induces the Fenton reaction-derived ferroptosis and the deterioration of liver disease. The elimination of the iron pool for the removal of Fenton reactions is vitally important to prevent the evolution of NAFLD, but quite challenging. In this work, we discover that free heme in the iron pool of NAFLD can catalyze the hydrogenation of H2O2/‧OH to block the heme-based Fenton reaction for the first time, and therefore develop a novel hepatocyte-targeted hydrogen delivery system (MSN-Glu) by modifying magnesium silicide nanosheets (MSN) with N-(3-triethoxysilylpropyl) gluconamide to block the heme-catalyzed vicious circle of liver disease. The developed MSN-Glu nanomedicine exhibits a high hydrogen delivery capacity as well as sustained hydrogen release and hepatocyte-targeting behaviors, and remarkably improves the metabolic function of the liver in a NAFLD mouse model by the relief of oxidative stress and the prevention of ferroptosis in hepatocytes, accelerating the removal of the iron pool in fundamental support of NAFLD prevention. The proposed prevention strategy based on the mechanisms of NAFLD disease and hydrogen medicine will provide an inspiration for inflammation-related disease prevention.

Association between serum iron and liver transaminases based on a large adult women population

BACKGROUND

Studies are being focused on the potential roles of iron in various diseases, but remain unclear for the association between serum iron and liver injury, especially in adult women.

METHODS

Based on the National Health and Nutrition Examination Survey, we investigated the relationship between serum iron and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) among 19,185 adult women.

RESULTS

Using weighted multivariate regression analyses, subgroup analyses, and threshold effect analyses, we found that serum iron was independently and positively correlated with ALT and AST. These associations differed in various age or race. Additionally, we found turning points in the curves of the relationship between serum iron and ALT in all women and the non-pregnant women. Using sensitivity analyses, we further found that the associations between serum iron and the liver transaminases remained positive in the non-pregnant women after adjusting for various covariates, but not in pregnant women. Besides, the positive associations between them kept present after excluding the women with high blood pressure, diabetes, and chronic kidney disease.

CONCLUSION

The present study indicated a positive association between serum iron and liver transaminases, indicating that serum iron may be a potential biomarker of liver function.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Relationship between iron overload caused by abnormal hepcidin expression and liver disease: A review

Iron is essential to organisms, the liver plays a vital role in its storage. Under pathological conditions, iron uptake by the intestine or hepatocytes increases, allowing excess iron to accumulate in liver cells. When the expression of hepcidin is abnormal, iron homeostasis in humans cannot be regulated, and resulting in iron overload. Hepcidin also regulates the release of iron from siderophores, thereby regulating the concentration of iron in plasma. Important factors related to hepcidin and systemic iron homeostasis include plasma iron concentration, body iron storage, infection, inflammation, and erythropoietin. This review summarizes the mechanism and regulation of iron overload caused by hepcidin, as well as related liver diseases caused by iron overload and treatment.

Iron overload in alcoholic liver disease: underlying mechanisms, detrimental effects, and potential therapeutic targets

Alcoholic liver disease (ALD) is a global public health challenge due to the high incidence and lack of effective therapeutics. Evidence from animal studies and ALD patients has demonstrated that iron overload is a hallmark of ALD. Ethanol exposure can promote iron absorption by downregulating the hepcidin expression, which is probably mediated by inducing oxidative stress and promoting erythropoietin (EPO) production. In addition, ethanol may enhance iron uptake in hepatocytes by upregulating the expression of transferrin receptor (TfR). Iron overload in the liver can aggravate ethanol-elicited liver damage by potentiating oxidative stress via Fenton reaction, promoting activation of Kupffer cells (KCs) and hepatic stellate cells (HSCs), and inducing a recently discovered programmed iron-dependent cell death, ferroptosis. This article reviews the current knowledge of iron metabolism, regulators of iron homeostasis, the mechanism of ethanol-induced iron overload, detrimental effects of iron overload in the liver, and potential therapeutic targets.

Iron chelates in the anticancer therapy

Iron plays a significant role in the metabolism of cancer cells. In comparison with normal cells, neoplastic ones exhibit enhanced vulnerability to iron. Ferric ions target tumor via the ferroptotic death pathway—a process involving the iron-mediated lipid oxidation. Ferric ion occurs in complex forms in the physiological conditions. Apart from iron, ligands are the other factors to affect the biological activity of the iron complexes. In recent decades the role of iron chelates in targeting the growth of the tumor was extensively examined. The ligand may possess a standalone activity to restrict cancer’s growth. However, a wrong choice of the ligand might lead to the enhanced cancer cell’s growth in in vitro studies. The paper aims to review the role of iron complex compounds in the anticancer therapy both in the experimental and clinical applications. The anticancer properties of the iron complex rely both on the stability constant of the complex and the ligand composition. When the stability constant is high, the properties of the drug are unique. However, when the stability constant remains low, both components—ferric ions and ligands, act separately on the cells. In the paper we show how the difference in complex stability implies the action of ligand and ferric ions in the cancer cell. Iron complexation strategy is an interesting attempt to transport the anticancer Fe2+/3+ ions throughout the cell membrane and release it when the pH of the microenvironment changes. Last part of the paper summarizes the results of clinical trials and in vitro studies of novel iron chelates such as: PRLX 93,936, Ferumoxytol, Talactoferrin, DPC, Triapine, VLX600, Tachypyridine, Ciclopiroxamine, Thiosemicarbazone, Deferoxamine and Deferasirox.

PPAR agonist fenofibrate attenuates iron-induced liver injury in mice by modulating the Sirt3 and -catenin signaling

Iron accumulation is frequently associated with chronic liver diseases. However, our knowledge on how iron contributes to the liver injury is limited. Aberrant Wnt/β-catenin signaling is a hallmark of several hepatic pathologies. We recently reported that peroxisome proliferator-activated receptor α (PPARα) agonist, fenofibrate, prevents iron-induced oxidative stress and β-catenin signaling by chelating the iron. Sirtuin3 (Sirt3), a type of NAD+-dependent deacetylase, that plays a critical role in metabolic regulation was found to prevent ischemia reperfusion injury (IRI) by normalizing the Wnt/β-catenin pathway. In the present study, we explored if fenofibrate prevents iron-induced liver injury by regulating the Sirt3 and β-catenin signaling. In vitro and in vivo iron treatment resulted in the downregulation of PPARα, Sirt3, active β-catenin, and its downstream target gene c-Myc in the mouse liver. Pharmacological activation of Sirt3, both in vitro and in vivo, by Honokiol (HK), a known activator of Sirt3, abrogated the inhibitory effect of iron overload on active β-catenin expression and prevented the iron-induced upregulation of α smooth muscle actin (αSMA) and TGFβ expression. Intrinsically, PPARα knockout mice showed significant downregulation of hepatic Sirt3 levels. In addition, treatment of iron overload mice with PPARα agonist fenofibrate reduced hepatic iron accumulation and prevented iron-induced downregulation of liver Sirt3 and active β-catenin, mitigating the progression of fibrosis. Thus, our results establish a novel link between hepatic iron and PPARα, Sirt3, and β-catenin signaling. Further exploration on the mechanisms by which fenofibrate ameliorates iron-induced liver injury likely has significant therapeutic impact on iron-associated chronic liver diseases.NEW & NOTEWORTHY Hepatic intracellular iron accumulation has been implicated in the pathophysiology of chronic liver diseases. In this study, we identified a novel mechanism involved in the progression of fibrosis. Excess iron accumulation in liver caused downregulation of PPARα-Sirt3-Wnt signaling leading to fibrosis. This work has significant translational potential as PPARα agonist fenofibrate could be an attractive therapeutic drug for the treatment of liver disorders associated with iron overload.

Phytic Acid Protects from Oxidative Stress Induced by Iron-Overload and High-Fat Diets in ß2-Microglobulin Knockout Mice

The objective of this study was to examine the protective effect of phytic acid (PA) in reducing oxidative stress in an animal model for human hereditary hemochromatosis (HH) fed high-fat diets. Sixty-four ß2 microglobulin knockout (β2m KO) mice were randomly assigned to three treatments by feeding: control (basal), atherogenic (AT), and polyunsaturated fatty acid (PUFA) diets. One-half of the mice in each treatment group were fed 2% (wt/wt) PA. The ß2m+/+ mice (wild type (WT)) were fed a basal diet. All seven groups were fed for 10 weeks with a 50-ppm iron-containing diet (AIN-93G). Free iron and lipids were measured in serum samples. Nonheme iron, thiobarbituric acid-reactive substances (TBARS), superoxide dismutase (SOD), and catalase concentrations were measured in the liver tissue. Nonheme iron concentration in ß2m KO mice (on the basal diet) was 20× higher (p < 0.0001) than in the WT mice. Compared to the WT mice, ß2m KO mice had a significantly higher concentration of free iron in the serum (p < 0.0001), six-fold higher hepatic TBARs (p < 0.0001), and 18% lower hepatic SOD level. When PA was added to the β2m KO basal diet, a reduction (26 to 50%) of iron concentration was seen in the liver and heart. The addition of PA also significantly reduced TBARs in all three dietary groups of the iron-overloaded group, but most effectively in the control group. An increase in SOD concentration was seen only in the PUFA group, but serum triacylglycerol (TG) concentration was reduced in both dietary fat groups. In conclusion, our results suggest that PA protects against oxidative stress-induced by genetic iron overload alone or when fed high fat.

An Indian Desert Shrub 'Hiran Chabba', Farsetia hamiltonii Royle, Exhibits Potent Antioxidant and Hepatoprotective Effect Against Iron- Overload Induced Liver Toxicity in Swiss Albino Mice

BACKGROUND

Farsetia hamiltonii Royle, also known as Hiran Chabba grows in desert regions. It is widely used as folk medicine to treat joint pains, diarrhea and diabetes. However, its antioxidant and iron chelation abilities both in vitro and in vivo have not yet been investigated.

METHODS

The 70% methanolic extract of F. hamiltonii (FHME) was investigated for its free radical scavenging and iron chelation potential, in vitro. An iron-overload situation was established by intraperitoneal injection of iron-dextran in Swiss albino mice, followed by oral administration of FHME. Liver damage and serum parameters due to iron-overload were measured biochemically and histopathologically to test iron-overload remediation and hepatoprotective potential of FHME. Phytochemical analyses were performed to determine its probable bioactive components.

RESULTS

FHME showed promising antioxidant activity, scavenged various reactive oxygen and nitrogen species and chelated iron in vitro. FHME reduced liver iron, serum ferritin, normalized serum parameters, reduced oxidative stress in liver, serum and improved liver antioxidant status in ironoverloaded mice. It also alleviated liver damage and fibrosis as evident from biochemical parameters and morphological analysis of liver sections. The phytochemical analyses of FHME reflected the presence of alkaloids, phenols, flavonoids and tannins. HPLC analysis indicated presence of tannic acid, quercetin, methyl gallate, catechin, reserpine, ascorbic acid and gallic acid.

CONCLUSION

Based on the experimental outcome, FHME, an ethnologically important plant can be envisaged as excellent antioxidant and iron chelator drug capable of remediating iron-overload induced hepatotoxicity and the bioactive compounds present in FHME might be responsible for its efficacy.

Hepatic transferrin plays a role in systemic iron homeostasis and liver ferroptosis

Although the serum-abundant metal-binding protein transferrin (encoded by the Trf gene) is synthesized primarily in the liver, its function in the liver is largely unknown. Here, we generated hepatocyte-specific Trf knockout mice (Trf-LKO), which are viable and fertile but have impaired erythropoiesis and altered iron metabolism. Moreover, feeding Trf-LKO mice a high-iron diet increased their susceptibility to developing ferroptosis-induced liver fibrosis. Importantly, we found that treating Trf-LKO mice with the ferroptosis inhibitor ferrostatin-1 potently rescued liver fibrosis induced by either high dietary iron or carbon tetrachloride (CCl4) injections. In addition, deleting hepatic Slc39a14 expression in Trf-LKO mice significantly reduced hepatic iron accumulation, thereby reducing ferroptosis-mediated liver fibrosis induced by either a high-iron diet or CCl4 injections. Finally, we found that patients with liver cirrhosis have significantly lower levels of serum transferrin and hepatic transferrin, as well as higher levels of hepatic iron and lipid peroxidation, compared with healthy control subjects. Taken together, these data indicate that hepatic transferrin plays a protective role in maintaining liver function, providing a possible therapeutic target for preventing ferroptosis-induced liver fibrosis.

Hepatic STAMP2 mediates recombinant FGF21-induced improvement of hepatic iron overload in nonalcoholic fatty liver disease

Although previous studies have shown that the administration of fibroblast growth factor 21 (FGF21) reverses hepatic steatosis, the mechanism by which FGF21 exerts a therapeutic effect on nonalcoholic fatty liver disease (NAFLD) is not yet entirely understood. We previously demonstrated that hepatic six transmembrane protein of prostate 2 (STAMP2) may represent a suitable target for NAFLD. We investigated the mechanism underlying the therapeutic effect of recombinant FGF21 on NAFLD, focusing on the involvement of hepatic STAMP2. In this study, we used human nonalcoholic steatosis patient pathology samples, C57BL/6 mice for a high-fat diet (HFD)-induced in vivo NAFLD model, and used human primary hepatocytes and HepG2 cells for oleic acid (OA)-induced in vitro NAFLD model. We observed that recombinant FGF21 treatment ameliorated hepatic steatosis and insulin resistance through the upregulation of STAMP2 expression. We further observed hepatic iron overload (HIO) and reduced iron exporter, ferroportin expression in the liver samples obtained from human NAFLD patients, and HFD-induced NAFLD mice and in OA-treated HepG2 cells. Importantly, recombinant FGF21 improved HIO through the hepatic STAMP2-mediated upregulation of ferroportin expression. Our data suggest that hepatic STAMP2 may represent a suitable therapeutic intervention target for FGF21-induced improvement of NAFLD accompanying HIO.

Protective effect of vitamin C and lycopene on the in vitro fertilization capacity of sex-sorted bull sperm by inhibiting the oxidative stress

The fertilization capacity of sex-sorted sperms is seriously decreased, which inhibits its wide application. However, little information is still available about the effect of vitamin C (VC) and lycopene (Lyc) on the fertilization capacity of sex-sorted bull sperm. In this study, the washing medium and fertilization medium of sex-sorted sperm from three bull individuals were supplemented with different concentrations of VC (0, 1 × 10^-3 , 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6  M) or Lyc (0, 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6 , 1 × 10^-7 ). After washing twice and incubation for 1.5 hr, the malondialdehyde (MDA) level, phosphatidylserine (PS) translocation, membrane potential (Δψm) and IVF (in vitro fertilization) ability of sex-sorted sperm were investigated. For the sex-sorted sperm of bulls A, B and C, 1 × 10^-3  M VC or 1 × 10^-4  M Lyc treatment significantly decreased their MDA levels and PS translocation and increased their Δψm levels and cleavage rates after IVF. When blastocysts were concerned, 1 × 10^-4  M Lyc significantly improved the blastocyst rates and their IFN-tau expression of bulls A and C. In conclusion, supplementation of 1 × 10^-3  M VC or 1 × 10^-4  M Lyc in washing and fertilization medium contributed greatly to improving the fertilization capacity of sex-sorted bull sperm during IVF procedure.

From Environment to Genome and Back: A Lesson from HFE Mutations

The environment and the human genome are closely entangled and many genetic variations that occur in human populations are the result of adaptive selection to ancestral environmental (mainly dietary) conditions. However, the selected mutations may become maladaptive when environmental conditions change, thus becoming candidates for diseases. Hereditary hemochromatosis (HH) is a potentially lethal disease leading to iron accumulation mostly due to mutations in the HFE gene. Indeed, homozygosity for the C282Y HFE mutation is associated with the primary iron overload phenotype. However, both penetrance of the C282Y variant and the clinical manifestation of the disease are extremely variable, suggesting that other genetic, epigenetic and environmental factors play a role in the development of HH, as well as, and in its progression to end-stage liver diseases. Alcohol consumption and dietary habits may impact on the phenotypic expression of HFE-related hemochromatosis. Indeed, dietary components and bioactive molecules can affect iron status both directly by modulating its absorption during digestion and indirectly by the epigenetic modification of genes involved in its uptake, storage and recycling. Thus, the premise of this review is to discuss how environmental pressures led to the selection of HFE mutations and whether nutritional and lifestyle interventions may exert beneficial effects on HH outcomes and comorbidities.

Inherited iron overload disorders

Hereditary iron overload includes several disorders characterized by iron accumulation in tissues, organs, or even single cells or subcellular compartments. They are determined by mutations in genes directly involved in hepcidin regulation, cellular iron uptake, management and export, iron transport and storage. Systemic forms are characterized by increased serum ferritin with or without high transferrin saturation, and with or without functional iron deficient anemia. Hemochromatosis includes five different genetic forms all characterized by high transferrin saturation and serum ferritin, but with different penetrance and expression. Mutations in HFE, HFE2, HAMP and TFR2 lead to inadequate or severely reduced hepcidin synthesis that, in turn, induces increased intestinal iron absorption and macrophage iron release leading to tissue iron overload. The severity of hepcidin down-regulation defines the severity of iron overload and clinical complications. Hemochromatosis type 4 is caused by dominant gain-of-function mutations of ferroportin preventing hepcidin-ferroportin binding and leading to hepcidin resistance. Ferroportin disease is due to loss-of-function mutation of SLC40A1 that impairs the iron export efficiency of ferroportin, causes iron retention in reticuloendothelial cell and hyperferritinemia with normal transferrin saturation. Aceruloplasminemia is caused by defective iron release from storage and lead to mild microcytic anemia, low serum iron, and iron retention in several organs including the brain, causing severe neurological manifestations. Atransferrinemia and DMT1 deficiency are characterized by iron deficient erythropoiesis, severe microcytic anemia with high transferrin saturation and parenchymal iron overload due to secondary hepcidin suppression. Diagnosis of the different forms of hereditary iron overload disorders involves a sequential strategy that combines clinical, imaging, biochemical, and genetic data. Management of iron overload relies on two main therapies: blood removal and iron chelators. Specific therapeutic options are indicated in patients with atransferrinemia, DMT1 deficiency and aceruloplasminemia.

Evaluation of serum iron overload, AST:ALT ratio and log10ferritin:AST ratio among schizophrenia patients in the Kumasi Metropolis, Ghana: a case-control study

OBJECTIVE

The association between unbalanced iron indices and the conditions of schizophrenia are not well understood. Liver dysfunction which has been linked to iron metabolism might be a contributing factor. This case-control study evaluated serum iron indices and liver function in treatment-naïve schizophrenia patients and those already on treatment at the Psychiatric Department of the Komfo Anokye Teaching Hospital (KATH), Kumasi-Ghana.

RESULTS

The mean age of the respondents was 39.6 ± 0.8 years. Increased levels of serum iron, TS, AST, ALT and AST:ALT ratio and lower levels of UIBC, TIBC, Transferrin, and log Ferritin:AST ratio levels were observed among the treatment-naïve group compared to the control. The treatment-naïve and treatment groups showed significantly higher serum AST:ALT ratio, and lower log10ferrtin:AST ratio than the healthy controls. There was a significant correlation between log10ferritin and AST, and log10ferritin and GGT in both treatments (r = 0.343; p = 0.003, and r = 0.502; p = 0.001 respectively) and treatment-naïve groups (r = 0.348; p = 0.002, and r = 0.614; p < 0.001 respectively). Percentage transferrin saturation correlated significantly with GGT only, in the treatment-naïve group (r = 0.667; p < 0.001), and ALT and GGT in the treatment group (r = 0.252; p = 0.030 and r = 0.646; p = 0.014 respectively).

Compound-specific adaptation of hepatoma cell lines to toxic iron

Cellular adaptation to excess iron (Fe) is a major determinant to protect tissues from toxicity. The adaptation of hepatoma cell lines following exposure to toxic levels of Fe compounds was studied. A dose- and time-dependent induction of toxicity was observed that was strictly compound-specific. Similar ranging orders of toxicity, i.e. iron chloride >iron sulfate >iron citrate, were observed in four human hepatoma cell lines. Long-term cultivation of HepG2 cells in 10 mM iron citrate resulted in a resistant cell line that displayed high proliferation rates for several months. Resistant cells showed increased viability at iron citrate concentrations ranging from 5-15 mM, while exposition to iron chloride or iron sulfate induced high rates of toxicity similar to parental cells. Resistance was not due to decreased Fe uptake/storage since high intracellular Fe levels were observed. A broad range of modulated gene expression was associated with short- and long-term iron citrate exposition; however, after weaning of resistant cells, re-exposition to Fe induced a similar level of toxicity as observed in parental cells suggesting that a transient adaptation of gene expression was mounted. The results indicate that, depending on the nature of the Fe compound, a specific level of toxicity is induced in hepatic cells which however can be overcome by establishment of resistance.

Effects of a moderate iron overload and its interaction with yacon flour, and/or phytate, in the diet on liver antioxidant enzymes and hepatocyte apoptosis in rats

The effect of moderate Fe overload in the diet and its interaction with phytate, and/or yacon flour (YF), recognized as an inhibitor, and facilitator, of Fe absorption, respectively, was evaluated in healthy rats. For this purpose the following parameters were analyzed: (1) apparent iron (Fe), copper (Cu) and zinc (Zn) absorption; (2) blood Fe; (3) blood lipids (cholesterol, tryacylglicerol); (4) blood AST and ALT; (5) liver histology (histopathology, hemosiderin depots, apoptosis index; (6) liver fatty acid incorporation; (7) liver antioxidant enzyme activity. Moderate Fe overload may cause change in some liver markers (hemosiderin depots, apoptosis index and GPx) and blood lipids (total cholesterol and VLDL) and the interaction with yacon flour, and phytate, in the Fe overloaded diets may exert a protective effect on these alterations.

Dietary iron restriction leads to a reduction in hepatic fibrosis in a rat model of non-alcoholic steatohepatitis

Iron overload in the liver causes oxidative stress and inflammation, which result in organ dysfunction, making it a risk factor for non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma. We aimed to evaluate the effect of dietary iron restriction on disease progression in rats fed a choline-deficient L-amino acid-defined (CDAA) diet. Male F344 rats were fed a choline-sufficient amino acid-defined (control) diet, a CDAA diet or an iron-restricted CDAA diet for 4, 8 and 12 weeks. At each time point, hepatic iron levels, oxidative stress, inflammation and fibrosis were evaluated by immunohistochemistry. The iron-restricted CDAA diet significantly decreased serum iron levels for 12 weeks compared with the CDAA diet. Histological analysis confirmed that feeding with the CDAA diet induced hepatic iron overload and that this was associated with oxidative stress (number of 8-hydroxydeoxyguanosine-positive cells), inflammation (CD68 positive area) and fibrosis (Sirius Red positive area). Iron restriction with the CDAA diet significantly led to a reduction in the hepatic iron levels, oxidative stress, inflammation and fibrosis. Therefore, dietary iron restriction could be a useful therapeutic approach for NASH patients with hepatic iron overload.

Summary: We reveal that dietary iron restriction leads to a reduction in hepatic inflammation, oxidative stress and fibrosis in rats fed a choline-deficient L-amino acid-defined (CDAA) diet.

A Systems Biology Approach to Understanding the Pathophysiology of High-Grade Serous Ovarian Cancer: Focus on Iron and Fatty Acid Metabolism

Ovarian cancer (OVC) is the most lethal of the gynecological malignancies, with diagnosis often occurring during advanced stages of the disease. Moreover, a majority of cases become refractory to chemotherapeutic approaches. Therefore, it is important to improve our understanding of the molecular dependencies underlying the disease to identify novel diagnostic and precision therapeutics for OVC. Cancer cells are known to sequester iron, which can potentiate cancer progression through mechanisms that have not yet been completely elucidated. We developed an algorithm to identify novel links between iron and pathways implicated in high-grade serous ovarian cancer (HGSOC), the most common and deadliest subtype of OVC, using microarray gene expression data from both clinical sources and an experimental model. Using our approach, we identified several links between fatty acid (FA) and iron metabolism, and subsequently developed a network for iron involvement in FA metabolism in HGSOC. FA import and synthesis pathways are upregulated in HGSOC and other cancers, but a link between these processes and iron-related genes has not yet been identified. We used the network to derive hypotheses of specific mechanisms by which iron and iron-related genes impact and interact with FA metabolic pathways to promote tumorigenesis. These results suggest a novel mechanism by which iron sequestration by cancer cells can potentiate cancer progression, and may provide novel targets for use in diagnosis and/or treatment of HGSOC.

The role of iron in hepatic inflammation and hepatocellular carcinoma

Iron is an essential for organisms and the liver plays a major role in its storage. In pathologic conditions, where iron absorption from the intestine or iron uptake into the hepatocytes is increased, excess iron accumulates in the hepatocytes, leading to hepatocyte injury through the production of free radicals. Iron exerts its toxicity by catalyzing the generation of reactive oxygen species (ROS). ROS causes cell injury by inducing damage to the lysosomal, cytoplasmic, nuclear and mitochondrial membranes, apoptosis through activation of the caspase cascade, and hyperoxidation of fatty chains. In this manuscript, we reviewed the articles regarding role of iron in hepatic inflammation and hepatocellular carcinoma.

Molecular mechanisms related to the hepatoprotective effects of antioxidant-rich extra virgin olive oil supplementation in rats subjected to short-term iron administration

Enhanced iron levels in liver are associated with oxidative stress development and damage with increased fat accumulation. The aim of this work was to assess the hypothesis that antioxidant-rich extra virgin olive oil (AR-EVOO) counteracts iron-rich diet (IRD)-induced oxidative stress hindering hepatic steatosis. Male Wistar rats were fed and IRD (200 mg iron/kg diet) versus a control diet (CD; 50 mg iron/kg diet) with alternate AR-EVOO supplementation (100 mg/day) for 21 days. IRD induced liver steatosis and oxidative stress (higher levels of protein oxidation and lipid peroxidation with glutathione depletion), mitochondrial dysfunction (decreased citrate synthase and complex I and II activities) and loss of polyunsaturated fatty acids (PUFAs), with a drastic enhancement in the sterol regulatory element-binding protein-1c (SREBP-1c)/peroxisome proliferator-activated receptor-α (PPAR-α) ratio upregulating the expression of lipogenic enzymes (acetyl-CoA carboxylase, fatty acid (FA) synthase and stearoyl desaturase 2) and downregulating those involved in FA oxidation (carnitine palmitoyl transferase and acyl-CoA oxidase) over values in the CD group. IRD also upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) and its target genes. AR-EVOO supplementation alone did not modify the studied parameters, however, IRD combined with AR-EVOO administration returned IRD-induced changes to baseline levels of the CD group. It is concluded that IRD-induced non-alcoholic fatty liver disease (NAFLD) is prevented by AR-EVOO supplementation, which might be related to the protective effects of its components such as hydroxytyrosol, oleic acid, tocopherols and/or PUFAs, thus representing a suitable anti-steatotic strategy to avoid progression into more severe stages of the disease, underlying NAFLD associated with iron overloading pathologies or obesity.

Phellinus rimosus improves mitochondrial energy status and attenuates nephrotoxicity in diabetic rats

BACKGROUND

Mitochondrial dysfunction and increase in reactive oxygen species during diabetes can lead to pathological consequences in kidneys. The present study was aimed to investigate the effect of Phellinus rimosus in the streptozotocin (STZ)-induced diabetic rat renal mitochondria and the possible mechanism of protection.

METHODS

Phellinus rimosus (50 and 250 mg/kg, p.o) was treated after inducing diabetes by STZ (45 mg/kg, i.p) in rats. The serum samples were subjected to creatinine and urea estimation. Mitochondrial antioxidant status such as mitochondrial superoxide dismutase, glutathione peroxidase, and reduced glutathione; adenosine triphosphate level; and lipid peroxidation were measured. The activities of Krebs cycle enzymes such as isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase as well as mitochondrial complexes I, III, and IV in kidney mitochondria were also determined.

RESULTS

Administration of P. rimosus (250 mg/kg b.wt) once daily for 30 days, significantly (p<0.05) enhanced the activities of Krebs cycle dehydrogenases, mitochondrial electron transport chain complexes, and ATP level. Further, P. rimosus had significantly protected the renal mitochondrial antioxidant status and lipid peroxidation.

CONCLUSIONS

The results of the study concluded that by limiting the extent of renal mitochondrial damage in the hyperglycemic state, P. rimosus alleviated nephrotoxicity.

Pediatric liver transplantation for fulminant hepatic failure secondary to intentional iron overdose

Acute iron poisoning may lead to life-threatening hepatotoxicity. We present the cases of two pediatric patients with hepatotoxicity following intentional iron ingestion that progressed rapidly to fulminant hepatic failure despite treatment with deferoxamine. Liver transplantation was lifesaving in both patients. These cases emphasize the need for a high index of suspicion for iron ingestion, close monitoring for liver toxicity, and timely consideration for liver transplantation.

The hepatocyte-specific HNF4α/miR-122 pathway contributes to iron overload-mediated hepatic inflammation

Hepatic iron overload (IO) is a major complication of transfusional therapy. It was generally thought that IO triggers substantial inflammatory responses by producing reactive oxygen species in hepatic macrophages. Recently, a decrease in microRNA-122 (miR-122) expression was observed in a genetic knockout (Hfe^-/-) mouse model of IO. Because hepatocyte-enriched miR-122 is a key regulator of multiple hepatic pathways, including inflammation, it is of interest whether hepatocyte directly contributes to IO-mediated hepatic inflammation. Here, we report that IO induced similar inflammatory responses in human primary hepatocytes and Thp-1-derived macrophages. In the mouse liver, IO resulted in altered expression of not only inflammatory genes but also >230 genes that are known targets of miR-122. In addition, both iron-dextran injection and a 3% carbonyl iron-containing diet led to upregulation of hepatic inflammation, which was associated with a significant reduction in HNF4α expression and its downstream target, miR-122. Interestingly, the same signaling pathway was changed in macrophage-deficient mice, suggesting that macrophages are not the only target of IO. Most importantly, hepatocyte-specific overexpression of miR-122 rescued IO-mediated hepatic inflammation. Our findings indicate the direct involvement of hepatocytes in IO-induced hepatic inflammation and are informative for developing new molecular targets and preventative therapies for patients with major hemoglobinopathy.

Bone morphogenetic protein-binding endothelial regulator of liver sinusoidal endothelial cells induces iron overload in a fatty liver mouse model

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is frequently accompanied by iron overload. However, because of the complex hepcidin-regulating molecules, the molecular mechanism underlying iron overload remains unknown. To identify the key molecule involved in NAFLD-associated iron dysregulation, we performed whole-RNA sequencing on the livers of obese mice.

METHODS

Male C57BL/6 mice were fed a regular or high-fat diet for 16 or 48 weeks. Internal iron was evaluated by plasma iron, ferritin or hepatic iron content. Whole-RNA sequencing was performed by transcriptome analysis using semiconductor high-throughput sequencer. Mouse liver tissues or isolated hepatocytes and sinusoidal endothelial cells were used to assess the expression of iron-regulating molecules.

RESULTS

Mice fed a high-fat diet for 16 weeks showed excess iron accumulation. Longer exposure to a high-fat diet increased hepatic fibrosis and intrahepatic iron accumulation. A pathway analysis of the sequencing data showed that several inflammatory pathways, including bone morphogenetic protein (BMP)-SMAD signaling, were significantly affected. Sequencing analysis showed 2314 altered genes, including decreased mRNA expression of the hepcidin-coding gene Hamp. Hepcidin protein expression and SMAD phosphorylation, which induces Hamp, were found to be reduced. The expression of BMP-binding endothelial regulator (BMPER), which inhibits BMP-SMAD signaling by binding BMP extracellularly, was up-regulated in fatty livers. In addition, immunohistochemical and cell isolation analyses showed that BMPER was primarily expressed in the liver sinusoidal endothelial cells (LSECs) rather than hepatocytes.

CONCLUSIONS

BMPER secretion by LSECs inhibits BMP-SMAD signaling in hepatocytes and further reduces hepcidin protein expression. These intrahepatic molecular interactions suggest a novel molecular basis of iron overload in NAFLD.

Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms

Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe²⁺) and ferric (Fe³⁺) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.

Genetic disruption of NRF2 promotes the development of necroinflammation and liver fibrosis in a mouse model of HFE-hereditary hemochromatosis

Background and Aims

In hereditary hemochromatosis, iron deposition in the liver parenchyma may lead to fibrosis, cirrhosis and hepatocellular carcinoma. Most cases are ascribed to a common mutation in the HFE gene, but the extent of clinical expression is greatly influenced by the combined action of yet unidentified genetic and/or environmental modifying factors. In mice, transcription factor NRF2 is a critical determinant of hepatocyte viability during exposure to acute dietary iron overload. We evaluated if the genetic disruption of Nrf2 would prompt the development of liver damage in Hfe^-/- mice (an established model of human HFE-hemochromatosis).

Methods

Wild-type, Nrf2^-/-, Hfe^-/- and double knockout (Hfe/Nrf2^-/-) female mice on C57BL/6 genetic background were sacrificed at the age of 6 (young), 12–18 (middle-aged) or 24 months (old) for evaluation of liver pathology.

Results

Despite the parenchymal iron accumulation, Hfe^-/- mice presented no liver injury. The combination of iron overload (Hfe^-/-) and defective antioxidant defences (Nrf2^-/-) increased the number of iron-related necroinflammatory lesions (sideronecrosis), possibly due to the accumulation of toxic oxidation products such as 4-hydroxy-2-nonenal-protein adducts. The engulfment of dead hepatocytes led to a gradual accumulation of iron within macrophages, featuring large aggregates. Myofibroblasts recruited towards the injury areas produced substantial amounts of collagen fibers involving the liver parenchyma of double-knockout animals with increased hepatic fibrosis in an age-dependent manner.

Conclusions

The genetic disruption of Nrf2 promotes the transition from iron accumulation (siderosis) to liver injury in Hfe^-/- mice, representing the first demonstration of spontaneous hepatic fibrosis in the long term in a mouse model of hereditary hemochromatosis displaying mildly elevated liver iron.

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Despite the parenchymal iron overload, single Hfe^-/- mice present no liver injury.

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Hfe and Nrf2 double knockout mice develop liver fibrosis with aging.

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Fibrosis is triggered by iron-related hepatocellular death (sideronecrosis).

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Nrf2 genetic disruption increases susceptibility to oxidative/electrophilic stress.

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NRF2 status is a potential determinant of liver injury in hemochromatosis.

Haemochromatosis

Haemochromatosis is now known to be an iron-storage disease with genetic heterogeneity but with a final common metabolic pathway resulting in inappropriately low production of the hormone hepcidin. This leads to increase in intestinal absorption and deposition of excessive amounts of iron in parenchymal cells which in turn results in eventual tissue damage and organ failure. A clinical enigma has been the variable clinical expression with some patients presenting with hepatic cirrhosis at a young age and others almost asymptomatic for life. Research is unravelling this puzzle by identifying environmental factors-especially alcohol consumption-and associated modifying genes that modulate phenotypic expression. A high index of suspicion is required for early diagnosis but this can lead to presymptomatic therapy and a normal life expectancy. Venesection (phlebotomy) therapy remains the mainstay of therapy, but alternative therapies are the subject of current research.

Reducing the iron burden and improving survival in transfusion-dependent thalassemia patients: current perspectives

Hypertransfusion regimens for thalassemic patients revolutionized the management of severe thalassemia; transforming a disease which previously led to early infant death into a chronic condition. The devastating effect of the accrued iron from chronic blood transfusions necessitates a more finely tuned approach to limit the complications of the disease, as well as its treatment. A comprehensive approach including carefully tailored transfusion protocol, continuous monitoring and assessment of total body iron levels, and iron chelation are currently the mainstay in treating iron overload. There are also indications for ancillary treatments, such as splenectomy and fetal hemoglobin induction. The main cause of death in iron overload continues to be related to cardiac complications. However, since the widespread use of iron chelation started in the 1970s, there has been a general improvement in survival in these patients.

Hepatotoxicity in acute iron poisoning

Although liver injury is a recognized consequence of acute iron poisoning, its description is limited to several case reports. It appears to be dose-related, however, there are published reports of severe iron poisoning without liver injury. The purpose of this study is to examine the hypothesis that this is a dose-related phenomenon and to identify the serum iron concentration of risk for this outcome. The design of this study is a retrospective review of our hospital's experience over 20 years. Extracted data included demographics, time of ingestion, highest serum iron concentration and highest hepatic transaminase activity. Iron poisoning was defined as a serum iron concentration / 300 mg/dL (55 mmol/L) within 12 hours of ingestion. Hepatotoxicity was defined as a serum transaminase (either ALT or AST) / 150 U/L. Severe hepatotoxicity was defined as / 1000 U/L. Seventy-three patients (1 / 704 mg/dL (55 / 48 years old) participated in the study and of these patients 60 (47 female) did not have hepatotoxicity. Their serum iron concentrations were 300 / 128 mmol/L). Thirteen patients had hepatotoxicity and of these patients, nine had severe liver injury. Severe injury was associated with serum iron concentrations well in excess of 1000 mg/dL (182 mmol/L). Our data support hepatotoxicity due to iron poisoning as a doserelated phenomenon with clinically important cases unlikely with a serum iron concentration of B / 700 mg/dL (128 mmol/L) within the first 12 hours. Clinically important hepatotoxicity occurs with values in excess of 1000 mg/dL (182 mmol/L).

Canine Liver Iron, Copper, and Zinc Concentrations and Association with Histologic Lesions

Concentrations of iron, copper, and zinc were measured in livers of 95 dogs that were suspected of having liver disease. Iron concentrations ranged from 177 to 7,680 ppm (dry weight basis); 54 dogs had iron concentrations greater than the normal concentration of 1,200 ppm. Iron stores were present in Kupffer cells and macrophages but not hepatocytes. The dogs did not have lesions of hemochromatosis. Dogs with high liver iron tended to have high liver copper and inflammatory lesions. High liver copper concentrations usually were associated with hepatocellular necrosis and fibrosis. High liver zinc was found in only 5 animals and was accompanied by histologic inflammatory lesions in one. In humans, increased iron concentration in the liver exacerbates liver damage caused by a variety of insults, and the same may be true for dogs.

Iron overload correlates with serum liver fibrotic markers and liver dysfunction: Potential new methods to predict iron overload-related liver fibrosis in thalassemia patients

BACKGROUND

Early detection of liver fibrosis in thalassemia patients and rapid initiation of treatment to interfere with its progression are extremely important.

OBJECTIVE

This study aimed to find a sensitive, easy-to-detect and noninvasive method other than liver biopsy for early detection of liver fibrosis in thalassemia patients.

METHODS

A total of 244 Chinese Thalassemia patients with non-transfusion-dependent thalassemia (NTDT, n = 105) or thalassemia major (TM, n = 139) and 120 healthy individuals were recruited into the present study, and blood collagen type IV (C IV), precollagen type III (PIIINPC) and hyaluronic acid (HA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and ferritin were measured. Liver iron concentration was determined by MRI. The correlation of serum markers with liver iron load and liver function was evaluated.

RESULTS

Serum C IV, PIIINPC and HA were significantly elevated in Chinese patients with NTDT and further elevated in TM patients. Moreover, C IV, PIIINPC and HA were also positively correlated to serum ferritin and liver iron concentration and further elevated during the progression to multi-organ damage in NTDT patients. Finally, serum ferritin and liver iron concentration were significantly correlated with liver dysfunction determined by AST and ALT.

CONCLUSION

Taken together, our results indicate that monitoring serum C IV, PIIINPC and HA is a potentially sensitive method to predict the risks for iron overload-related liver fibrosis in Chinese thalassemia patients.

Resveratrol mediates therapeutic hepatic effects in acquired and genetic murine models of iron-overload

BACKGROUND & AIMS

Abnormal iron metabolism and hepatic iron-overload is a major cause of liver injury and in the development of chronic liver diseases. Iron-overload-mediated liver disease leads to end-stage cirrhosis and/or hepatocellular carcinoma.

METHODS

Using a genetic hemochromatosis (hemojuvelin knockout mice) and non-genetic (secondary iron-overload) murine models of hepatic iron-overload, we elucidated the mechanism of hepatic iron injury and the therapeutic effects of resveratrol.

RESULTS

Hepatic iron-overload was associated with hepatosplenomegaly, increased oxidative stress, hepatic fibrosis, and inflammation, and a pro-apoptotic state which was markedly corrected by resveratrol therapy. Importantly our aging studies with the hemojuvelin knockout mice showed advanced liver disease in association with steatosis in the absence of a diabetic state which recapitulates the essential pathological features seen in clinical iron-overload. Chronic hepatic iron-overload showed increased nuclear localization of acetylated Forkhead fox-O-1 (FoxO1) transcription factor whereas resveratrol dietary intervention reversed the acetylation of FoxO1 in association with increased SIRT1 levels which together with its pleotropic antioxidant properties are likely key mechanisms of its therapeutic action. Importantly, resveratrol treatment did not affect the degree of hepatic iron-overload but rather direct protects the liver from iron-mediated injury.

CONCLUSIONS

Our findings illustrate a novel and definitive therapeutic action of resveratrol and represent an economically feasible therapeutic intervention to treat hepatic iron-overload and liver disease.

Biomarker-Based Approaches for Assessing Alcohol Use Disorders

Although alcohol use disorders rank among the leading public health problems worldwide, hazardous drinking practices and associated morbidity continue to remain underdiagnosed. It is postulated here that a more systematic use of biomarkers improves the detection of the specific role of alcohol abuse behind poor health. Interventions should be initiated by obtaining information on the actual amounts of recent alcohol consumption through questionnaires and measurements of ethanol and its specific metabolites, such as ethyl glucuronide. Carbohydrate-deficient transferrin is a valuable tool for assessing chronic heavy drinking. Activities of common liver enzymes can be used for screening ethanol-induced liver dysfunction and to provide information on the risk of co-morbidities including insulin resistance, metabolic syndrome and vascular diseases. Conventional biomarkers supplemented with indices of immune activation and fibrogenesis can help to assess the severity and prognosis of ethanol-induced tissue damage. Many ethanol-sensitive biomarkers respond to the status of oxidative stress, and their levels are modulated by factors of life style, including weight gain, physical exercise or coffee consumption in an age- and gender-dependent manner. Therefore, further attention should be paid to defining safe limits of ethanol intake in various demographic categories and establishing common reference intervals for biomarkers of alcohol use disorders.

Hepatic Deficiency of Augmenter of Liver Regeneration Exacerbates Alcohol-Induced Liver Injury and Promotes Fibrosis in Mice

Why only a subpopulation (about 15%) of humans develops liver cirrhosis due to alcohol is a critical as yet unanswered question. Liver-specific depletion of augmenter of liver regeneration (ALR) protein in mice causes robust steatosis and hepatocyte apoptosis by 2 weeks; these pathologies regress subsequently with return of ALR expression even at lower than control levels, but the mice develop modest steatohepatitis by 8 weeks. We aimed to investigate whether chronic alcohol ingestion promotes excessive hepatic fibrosis in these ALR-deficient mice. Liver-specific ALR-deficient and wild type (WT) female mice (8–10 weeks old) were placed on 4% alcohol-supplemented or isocaloric diet for 4 weeks. Liver sections were examined for histopathology, and parameters of steatosis and fibrosis were quantified. The mRNA expression of alcohol dehydrogenase-1, acetaldehyde dehydrogenase-1 and cytochrome P450-2E1 increased in WT mice but decreased in ALR-deficient mice upon alcohol ingestion. While alcohol induced steatosis and mild inflammation in WT mice, ALR-deficient mice showed minimal steatosis, strong hepatocellular injury and inflammation, prominent ductular proliferation, and robust fibrosis. Compared to the WT mice, alcohol feeding of ALR-deficient mice resulted in significantly greater increase in hepatic TNFα and TGFβ, and oxidative stress; there was also hepatic iron accumulation, robust lipid peroxidation and mitochondrial DNA damage. Importantly, similar to ALR-deficient mice, lower hepatic ALR levels in human alcoholic liver cirrhosis were associated with increased iron content, reduced expression of alcohol dehydrogenase and acetaldehyde dehydrogenase, and elevated fibrogenic markers. We conclude that ALR deficiency or anomaly can play a critical role in alcohol-induced hepatic fibrosis/cirrhosis, mechanisms of which may involve dysregulation of alcohol metabolism and iron homeostasis, mitochondrial damage and oxidative injury.

Deciphering the Nongenomic, Mitochondrial Toxicity of Tamoxifens As Determined by Cell Metabolism and Redox Activity

Tamoxifen is not only considered a very potent chemotherapeutic adjuvant for estrogen receptor positive breast cancers but also a very good chemo-preventive drug. Recently, there has been a rising amount of evidence for a nongenomic cytotoxicity of tamoxifen, even in estrogen receptor negative cells, which has greatly confounded researchers. Clinically, the side effects of tamoxifen can be very serious, ranging from liver steatosis to cirrhosis, tumorigenesis, or onset of porphyrias. Herein, we deciphered the nongenomic, mitochondrial cytotoxicity of tamoxifen in estrogen receptor positive MCF7 versus triple-negative MDA-MB-231 cells, employing the mitochondrial complex III quinoloxidizing-center inhibitor myxothiazol. We showed a role for hydroxyl-radical-mediated lipid peroxidation, catalyzed by iron, stemming from the redox interactions of tamoxifen quinoid metabolites with complex III, resulting in Fenton-capable reduced quinones. The role of tamoxifen semiquinone species in mitochondrial toxicity was also shown together with evidence of mitochondrial DNA damage. Tamoxifen caused an overall metabolic (respiratory and glycolytic) rate decrease in the Pasteur type MCF cells, while in the Warburg type MDA-MB-231 cells the respiratory rate was not significantly affected and the glycolytiv rate was significantly boosted. The nongenomic cytotoxicity of tamoxifens was hence associated with the metabolic phenotype and redox activity of the cells, as in the present paradigm of Pasteur MCF7s versus Warburg MDA-MB-231 cells. Our present findings call for caution in the use of the drugs, especially as a chemopreventive and/or in cases of iron overload diseases.

Iron-Mediated Lysosomal Membrane Permeabilization in Ethanol-Induced Hepatic Oxidative Damage and Apoptosis: Protective Effects of Quercetin

Iron, in its free ferrous states, can catalyze Fenton reaction to produce OH∙, which is recognized as a crucial role in the pathogenesis of alcoholic liver diseases (ALD). As a result of continuous decomposition of iron-containing compounds, lysosomes contain a pool of redox-active iron. To investigate the important role of intralysosomal iron in alcoholic liver injury and the potential protection of quercetin, male C57BL/6J mice fed by Lieber De Carli diets containing ethanol (30% of total calories) were cotreated by quercetin or deferoxamine (DFO) for 15 weeks and ethanol-incubated mice primary hepatocytes were pretreated with FeCl3, DFO, and bafilomycin A1 at their optimal concentrations and exposure times. Chronic ethanol consumption caused an evident increase in lysosomal redox-active iron accompanying sustained oxidative damage. Iron-mediated ROS could trigger lysosomal membrane permeabilization (LMP) and subsequent mitochondria apoptosis. The hepatotoxicity was attenuated by reducing lysosomal iron while being exacerbated by escalating lysosomal iron. Quercetin substantially alleviated the alcoholic liver oxidative damage and apoptosis by decreasing lysosome iron and ameliorating iron-mediated LMP, which provided a new prospective of the use of quercetin against ALD.

Inconsistent hepatic antifibrotic effects with the iron chelator deferasirox

BACKGROUND AND AIM

Development of effective antifibrotic treatments that can be translated to clinical practice is an important challenge in contemporary hepatology. A recent report on β-thalassemia patients demonstrated that deferasirox treatment reversed or stabilized liver fibrosis independent of its iron-chelating properties. In this study, we investigated deferasirox in cell and animal models to better understand its potential antifibrotic effects.

METHODS

The LX-2 stellate cell line was treated with 5 μM or 50 μM deferasirox (Exjade, Novartis Pharmaceuticals Australia, North Ryde, NSW, Australia) for up to 120 h. Three-week-old multidrug resistance 2 null (Mdr2(-/-) ) mice received oral deferasirox or vehicle for 4 weeks (30 mg/kg/day). Cells and liver tissue were collected for assessment of fibrosis and fibrogenic gene expression.

RESULTS

In LX-2 cells treated with 50 μM deferasirox for 12 h, α1(I)procollagen expression was decreased by 25%, with maximal reductions (10-fold) seen following 24-120 h of treatment. Similarly, α-smooth muscle actin (αSMA) expression was significantly lower. Alterations in matrix remodeling genes, specifically decreased expression of matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2, were observed. There was no significant difference in hepatic hydroxyproline content in Mdr2(-/-) mice following deferasirox administration (vehicle: 395 ± 27 μg/g vs deferasirox: 421 ± 33 μg/g). Similarly, no changes in the expression of fibrogenic genes were observed.

CONCLUSION

Despite reductions in α1(I)procollagen and αSMA expression and alterations in matrix degradation genes in LX-2 cells, deferasirox did not exhibit antifibrotic activity in Mdr2(-/-) mice. Given the positive outcomes seen in human trials, it may be appropriate to study deferasirox in other animal models of fibrosis and/or for a longer duration of therapy.

Diagnosis and management of hereditary hemochromatosis

Hereditary hemochromatosis is a rare genetic disorder that can have significant clinical consequences. Hemochromatosis is associated with iron overload, and can initially be recognized through laboratory testing for serum ferritin and transferrin saturation. Genetic testing for the HFE mutation can be performed in patients with elevated iron indices and a suspicion for hemochromatosis or liver disease. The main pathway resulting in iron overload is through altered hepcidin levels. Treatment of patients with the clinical phenotype of hereditary hemochromatosis is commonly through phlebotomy for removal of excess iron stores. This article highlights the current information and data regarding the diagnosis and management of hemochromatosis.

HFE gene variants and iron-induced oxygen radical generation in idiopathic pulmonary fibrosis

In idiopathic pulmonary fibrosis (IPF), lung accumulation of excessive extracellular iron and macrophage haemosiderin may suggest disordered iron homeostasis leading to recurring microscopic injury and fibrosing damage. The current study population comprised 89 consistent IPF patients and 107 controls. 54 patients and 11 controls underwent bronchoalveolar lavage (BAL). Haemosiderin was assessed by Perls' stain, BAL fluid malondialdehyde (MDA) by high-performance liquid chromatography, BAL cell iron-dependent oxygen radical generation by fluorimetry and the frequency of hereditary haemochromatosis HFE gene variants by reverse dot blot hybridisation. Macrophage haemosiderin, BAL fluid MDA and BAL cell unstimulated iron-dependent oxygen radical generation were all significantly increased above controls (p<0.05). The frequency of C282Y, S65C and H63D HFE allelic variants was markedly higher in IPF compared with controls (40.4% versus 22.4%, OR 2.35, p=0.008) and was associated with higher iron-dependent oxygen radical generation (HFE variant 107.4±56.0, HFE wild type (wt) 59.4±36.4 and controls 16.7±11.8 fluorescence units per 10(5) BAL cells; p=0.028 HFE variant versus HFE wt, p=0.006 HFE wt versus controls). The data suggest iron dysregulation associated with HFE allelic variants may play an important role in increasing susceptibility to environmental exposures, leading to recurring injury and fibrosis in IPF.

Hemochromatosis: the new blood donor

Hereditary hemochromatosis (HH) due to homozygosity for the C282Y mutation in the HFE gene is a common inherited iron overload disorder in whites of northern European descent. Hepcidin deficiency, the hallmark of the disorder, leads to dysregulated intestinal iron absorption and progressive iron deposition in the liver, heart, skin, endocrine glands, and joints. Survival is normal if organ damage is prevented by early institution of phlebotomy therapy. HH arthropathy is the symptom most affecting quality of life and can be debilitating. Genotype screening in large population studies has shown that the clinical penetrance of C282Y homozygosity is highly variable and can be very low, with up to 50% of women and 20% of men showing a silent phenotype. Targeted population screening for the HFE C282Y mutation is not recommended at present, but might be reconsidered as a cost-effective approach to management if counseling and care were better organized and standardized. Referral of patients to the blood center for phlebotomy therapy and use of HH donor blood for transfusion standardizes treatment, minimizes treatment costs, and may benefit society as a whole. Physician practices should be amended such that HH subjects are more frequently referred to the blood center for therapy.