Unraveling mechanisms regulating systemic iron homeostasis

Iron; Benefits or threatens (with emphasis on mechanism and treatment of its poisoning)

Iron is a necessary biological element and one of the richest in the human body, but it can cause changes in cell function and activity control. Iron is involved in a wide range of oxidation - reduction activities. Whenever iron exceeds the cellular metabolic needs, its excess causes changes in the products of cellular respiration, such as superoxide, hydrogen peroxide and hydroxyl. The formation of these compounds causes cellular toxicity. Lack of control over reactive oxygen species causes damages to DNA, proteins, and lipids. Conversely, superoxide, hydrogen peroxide and hydroxyl are reactive oxygen species, using antioxidants, restoring DNA function, and controlling iron stores lead to natural conditions. Iron poisoning causes clinical manifestations in the gastrointestinal tract, liver, heart, kidneys, and hematopoietic system. When serum iron is elevated, serum iron concentrations, total iron-binding capacity (TIBC) and ferritin will also increase. Supportive care is provided by whole bowel irrigation (WBI), esophagogastroduodenoscopy is required to evaluate mucosal injury and remove undissolved iron tablets. The use of chelator agents such as deferoxamine mesylate, deferasirox, deferiprone, deferitrin are very effective in removing excess iron. Of course, the combined treatment of these chelators plays an important role in increasing iron excretion, and reducing side effects.

Chronic Heart Failure: Clinical Implications of Iron Homeostasis Disturbances Revisited

Iron deficiency is prevalent in chronic heart failure (CHF) patients. Nonetheless, the diagnosis is often overlooked and, often, the treatment is commenced just when overt anemia has ensued. Therefore, a better appreciation of this disease is needed, and all seasoned cardiologists should know how to approach CHF patients with iron deficiency correctly, as mandated by clinical practice guidelines. In this comprehensive review, we describe iron homeostasis, the pathophysiologic changes of iron homeostasis, and the clinical implications of iron deficiency on CHF patients. In addition, we delineate the evolution of clinical trials, ranging from the inception to the ongoing clinical trials of iron deficiency treatment in CHF patients. Iron deficiency contributes to the worse clinical outcome of the patients. Numerous studies have reported the clinical benefit of iron supplementation, particularly in intravenous preparation, in heart failure patients regarding symptoms, functional capacity, and quality of life (QoL) improvement. Therefore, the current guidelines recommend routine screening of iron status in all newly diagnosed heart failure patients. Eventually, intravenous iron replacement is recommended for symptomatic heart failure patients with iron deficiency, irrespective of anemia.

Hematological Abnormalities and Comorbidities Are Associated With the Severity of Kidney Disease: A Hospital-Based Cross-Sectional Study in Bangladesh

Background

Abnormalities in hematology and comorbidities might have a role in chronic kidney disease (CKD) patients. However, the exact relationships between hematological parameters and the severity of CKD are not well understood. Also, the underlying mechanisms remain under investigation. The present study aimed to evaluate the association of different blood parameters and comorbidities among hospitalized CKD patients in Bangladesh.

Methods

The present study enrolled admitted CKD patients at Evercare Hospital Ltd, Dhaka, Bangladesh, from January 1, 2021, to August 1, 2021. For this study, the demographic and clinical information of the patients were collected. Then some routine blood tests for the hematological profile of CKD patients were performed. Finally, several statistical methods were performed and data interpretations were done to evaluate the role of hematological changes on CKD patients.

Results

Among 300 patients, early-stage CKD patients (ESCKDP) and advanced-stage CKD patients (ASCKDP) were 153 and 147, respectively. The decreased levels of hemoglobin (Hb) and red blood cell (RBC) in ASCKDP were observed. However, the present study found increased levels of corpuscular Hb in ASCKDP than ESCKDP. Also, the present study noticed correlations between these changes and the severity of CKD. Also, we observed a significant difference in age and body mass index between ESCKDP and ASCKDP.

Conclusions

Based on our results, lower Hb and RBC levels may use in assessing the severity and the treatment decisions of CKD patients in the hospital setting. Therefore, our findings may assist with developing a treatment protocol for hospitalized CKD patients.

Plasma Levels of Hepcidin and Reticulocyte Haemoglobin during Septic Shock

Septic shock, a serious consequence of disseminated infection that has a high mortality, is due to a dysregulated, severe immune response triggered by the infection. Acute phase reactants play key roles in sepsis, for example, hepcidin regulating iron metabolism. Reticulocyte haemoglobin (Ret-He) depends on available iron in blood, indirectly regulated by hepcidin. This study aimed at exploring rapid changes in hepcidin and Ret-He in patients with septic shock receiving adequate antibiotic treatment. Fifteen patients, included within an hour of admission to the intensive care unit, were evaluated by microbiological tests and cultures, Sequential Organ Failure Assessment score, and plasma levels of hepcidin, Ret-He, heparin-binding protein (HBP), leucocytes, C-reactive protein, procalcitonin (PCT), and lactate. Samples were taken every morning for 7 consecutive days. Maximal levels of hepcidin (median 61 nmol/L; reference 1-12 nmol/L) were seen at the time of inclusion, then declining steadily similar to PCT and lactate levels. Ret-He values decreased transiently in response to increased hepcidin, normalization occurred at 96 h upon decrease of hepcidin levels. Maximal levels of HBP were noted 24 h after inclusion. In conclusion, hepcidin promptly declined within the first 24 h in patients with septic shock receiving adequate antibiotic treatment in contrast to Ret-He and HBP.

Iron in Lung Pathology

The lung presents a unique challenge for iron homeostasis. The entire airway is in direct contact with the environment and its iron particulate matter and iron-utilizing microbes. However, the homeostatic and adaptive mechanisms of pulmonary iron regulation are poorly understood. This review provides an overview of systemic and local lung iron regulation, as well as the roles of iron in the development of lung infections, airway disease, and lung injury. These mechanisms provide an important foundation for the ongoing development of therapeutic applications.

Effect of exercise on serum markers of muscle inflammation in Spanish Greyhounds

OBJECTIVE

To investigate effects of exercise on hematologic and biochemical values (especially markers of inflammation and muscle damage) in Spanish Greyhounds used for hunting without previous training.

ANIMALS

32 Spanish Greyhounds and 31 dogs of other breeds.

PROCEDURES

Hematologic variables and concentrations of C-reactive protein (CRP) and other biochemical markers were compared in samples obtained from Spanish Greyhounds 24 hours after exercise (eg, a hunting race) and 2 months after exercise (ie, at rest) and from non-Spanish Greyhounds at rest. All dogs were healthy. Hematologic and biochemical analyses were performed within 24 hours after samples were obtained, and results were compared by means of a Student t test.

RESULTS

CRP concentration and muscle enzyme (creatine kinase, lactate dehydrogenase, and aspartate aminotransferase) activities were significantly higher and serum iron concentration was significantly lower for Spanish Greyhounds after exercise than at rest. The WBC and neutrophil counts were significantly higher after exercise then at rest. Plasma alanine transaminase activity and total protein, calcium, and phosphorus concentrations were significantly higher after exercise than at rest. Spanish Greyhounds at rest had higher RBC counts, PCVs, and hemoglobin concentrations and lower WBC, neutrophil, and lymphocyte counts, compared with values for non-Spanish Greyhounds at rest.

CONCLUSIONS AND CLINICAL RELEVANCE

Exercise of Spanish Greyhounds without prior training activated an acute-phase response represented by an increase in serum CRP concentration and decrease in serum albumin and iron concentrations. These changes, along with leukocytosis and neutrophilia, were indicative of a subclinical inflammatory state in Spanish Greyhounds.

Resistance to Recombinant Human Erythropoietin Therapy in a Rat Model of Chronic Kidney Disease Associated Anemia

This study aimed to elucidate the mechanisms explaining the persistence of anemia and resistance to recombinant human erythropoietin (rHuEPO) therapy in a rat model of chronic kidney disease (CKD)-associated anemia with formation of anti-rHuEPO antibodies. The remnant kidney rat model of CKD induced by 5/6 nephrectomy was used to test a long-term (nine weeks) high dose of rHuEPO (200 UI/kg bw/week) treatment. Hematological and biochemical parameters were evaluated as well as serum and tissue (kidney, liver and/or duodenum) protein and/or gene expression of mediators of erythropoiesis, iron metabolism and tissue hypoxia, inflammation, and fibrosis. Long-term treatment with a high rHuEPO dose is associated with development of resistance to therapy as a result of antibodies formation. In this condition, serum EPO levels are not deficient and iron availability is recovered by increased duodenal absorption. However, erythropoiesis is not stimulated, and the resistance to endogenous EPO effect and to rHuEPO therapy results from the development of a hypoxic, inflammatory and fibrotic milieu in the kidney tissue. This study provides new insights that could be important to ameliorate the current therapeutic strategies used to treat patients with CKD-associated anemia, in particular those that become resistant to rHuEPO therapy.

Iron therapy in chronic kidney disease: Recent changes, benefits and risks

Anemia is a common complication in patients with chronic kidney disease (CKD), mainly due to inadequate renal production of erythropoietin. In hemodialysis (HD) patients this condition may be aggravated by iron deficiency (absolute or functional). The correction of this anemia is usually achieved by treatment with erythropoiesis stimulating agents (ESAs) and iron (oral or intravenous). Studies questioning the safety of ESAs (especially at higher doses) changed the pattern of anemia treatment in CKD patients. According to the new guidelines, when transferrin saturation is lower than 30% and ferritin lower than 500 ng/mL, a trial with iron should be started, to avoid therapy with ESAs or at least to reduce the doses needed to treat the anemia. Recent reports showed increasing ferritin levels, towards values above 800 ng/mL, in CKD patients treated according to the guidelines. In this review we focus on the risks of the increased iron use to treat CKD anemia, namely, iron overload and toxicity, increased risk of infections, as well as mortality.

Iron as the key modulator of hepcidin expression in erythroid antibody-mediated hypoplasia

Erythroid hypoplasia (EH) is a rare complication associated with recombinant human erythropoietin (rHuEPO) therapies, due to development of anti-rHuEPO antibodies; however, the underlying mechanisms remain poorly clarified. Our aim was to manage a rat model of antibody-mediated EH induced by rHuEPO and study the impact on iron metabolism and erythropoiesis. Wistar rats treated during 9 weeks with a high rHuEPO dose (200 IU) developed EH, as shown by anemia, reduced erythroblasts, reticulocytopenia, and plasmatic anti-rHuEPO antibodies. Serum iron was increased and associated with mRNA overexpression of hepatic hepcidin and other iron regulatory mediators and downregulation of matriptase-2; overexpression of divalent metal transporter 1 and ferroportin was observed in duodenum and liver. Decreased EPO expression was observed in kidney and liver, while EPO receptor was overexpressed in liver. Endogenous EPO levels were normal, suggesting that anti-rHuEPO antibodies blunted EPO function. Our results suggest that anti-rHuEPO antibodies inhibit erythropoiesis causing anemia. This leads to a serum iron increase, which seems to stimulate hepcidin expression despite no evidence of inflammation, thus suggesting iron as the key modulator of hepcidin synthesis. These findings might contribute to improving new therapeutic strategies against rHuEPO resistance and/or development of antibody-mediated EH in patients under rHuEPO therapy.

Iron overload induces changes of pancreatic and duodenal divalent metal transporter 1 and prohepcidin expression in mice

It is well known that the iron content of the body is tightly regulated. Iron excess induces adaptive changes that are differentially regulated in each tissue. The pancreas is particularly susceptible to iron-related disorders. We studied the expression and regulation of key iron proteins in the pancreas, duodenum and liver, using an animal model of iron overload (female CF1 mice injected i.p. with iron saccharate, colloidal iron form). Divalent metal transporter 1, prohepcidin and ferritin (pancreas, duodenum, liver) were assessed by immunohistochemistry; divalent metal transporter 1 (pancreas, duodenum) by Western blot. In the iron overloaded mice, prohepcidin expression increased in islets of Langerhans and hepatocytes, and divalent metal transporter 1 expression decreased in cells of islets and in enterocytes. In the iron overloaded mice, ferritin expression decreased in islets of Langerhans and increased in acinar cells; hemosiderin was localized in connective tissue cells. The inverse relationship between divalent metal transporter 1 and prohepcidin may indicate a negative regulation by hepcidin, and hence reduction of iron stores in islets of Langerhans. Our data showed that in iron overloaded mice model, induced by colloidal iron form, a coordinated expression of key iron proteins in the pancreas, duodenum and liver may occur. Further research will be necessary to determine the adaptive responses induced by iron in the pancreas.

Testosterone perturbs systemic iron balance through activation of epidermal growth factor receptor signaling in the liver and repression of hepcidin

Gender-related disparities in the regulation of iron metabolism may contribute to the differences exhibited by men and women in the progression of chronic liver diseases associated with reduced hepcidin expression, e.g., chronic hepatitis C, alcoholic liver disease, or hereditary hemochromatosis. However, their mechanisms remain poorly understood. In this study we took advantage of the major differences in hepcidin expression and tissue iron loading observed between Bmp6-deficient male and female mice to investigate the mechanisms underlying this sexual dimorphism. We found that testosterone robustly represses hepcidin transcription by enhancing Egfr signaling in the liver and that selective epidermal growth factor receptor (Egfr) inhibition by gefitinib (Iressa) in males markedly increases hepcidin expression. In males, where the suppressive effects of testosterone and Bmp6-deficiency on hepcidin expression are combined, hepcidin is more strongly repressed than in females and iron accumulates massively not only in the liver but also in the pancreas, heart, and kidneys.

CONCLUSION

Testosterone-induced repression of hepcidin expression becomes functionally important during homeostatic stress from disorders that result in iron loading and/or reduced capacity for hepcidin synthesis. These findings suggest that novel therapeutic strategies targeting the testosterone/EGF/EGFR axis may be useful for inducing hepcidin expression in patients with iron overload and/or chronic liver diseases.

Review on iron and its importance for human health

It is well-known that deficiency or over exposure to various elements has noticeable effects on human health. The effect of an element is determined by several characteristics, including absorption, metabolism, and degree of interaction with physiological processes. Iron is an essential element for almost all living organisms as it participates in a wide variety of metabolic processes, including oxygen transport, deoxyribonucleic acid (DNA) synthesis, and electron transport. However, as iron can form free radicals, its concentration in body tissues must be tightly regulated because in excessive amounts, it can lead to tissue damage. Disorders of iron metabolism are among the most common diseases of humans and encompass a broad spectrum of diseases with diverse clinical manifestations, ranging from anemia to iron overload, and possibly to neurodegenerative diseases. In this review, we discuss the latest progress in studies of iron metabolism and bioavailability, and our current understanding of human iron requirement and consequences and causes of iron deficiency. Finally, we discuss strategies for prevention of iron deficiency.

Inappropriate expression of hepcidin by liver congestion contributes to anemia and relative iron deficiency

BACKGROUND

Anemia and relative iron deficiency (RID) are prevalent in patients with heart failure (HF). The etiology of anemia and RID in HF patients is unclear. Hepcidin expression may be closely related to anemia and RID in HF patients. Although hepcidin is produced mainly by the liver, and the most frequent histologic appearance of liver in HF patients is congestion, the influence of liver congestion (LC) on hepcidin production has not yet been investigated. We investigated whether hepcidin contributed to anemia and RID in rats with LC.

METHODS AND RESULTS

LC was induced in rats by ligating the inferior vena cava and compared with bleeding anemia (BA) model induced by phlebotomy and hemolytic anemia (HA) model induced by injection of phenylhydrazine. BA and HA strongly suppressed expression of hepcidin in liver and so did not cause decrease in serum iron and transferrin saturation. However, hepcidin expression did not decrease in LC rats, which resulted in anemia and lower transferrin saturation. In addition, many cells with hemosiderin deposits were observed in the liver and spleen and not in the bone marrow, and this appeared to be related to suppression of hepcidin expression. Iron accumulated in hepatocytes, and bone morphogenetic protein 6, which induces hepcidin, increased. Inflammation was observed in the congestive liver, and there was an increase in interleukin-6, which also induced hepcidin and was induced by free heme and hemoglobin via Toll-like receptor 4.

CONCLUSIONS

We conclude that LC contributes to RID and anemia, and it does so via inappropriate expression of hepcidin.

Ferroportin in the progression and prognosis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the fifth most common malignant tumor in men and the seventh in women and understanding the molecular mechanisms of HCC and establishing more effective therapies are critical and urgent issues. Our objective was to study the expression of ferroportin in hepatocellular carcinoma (HCC) tissue samples and the relationship between ferroportin expression and HCC characteristics.

METHODS

Sixty HCC tissues and their corresponding para-cancer liver tissues (PCLT) were obtained from sixty HCC patients who had undergone hepatectomy in the Second Xiangya Hospital of Central South University. Ten normal liver tissue samples were also obtained as a control. Immunohistochemistry (IHC) was performed to analyze the ferroportin expression in HCC, and the relationship between ferroportin expression and HCC clinical pathological characteristics also was analyzed. For the evaluation of IHC results, the comprehensive scoring criteria were met according to the staining intensity and the number of positive staining cells. Western blotting was performed to detect the expression level of ferroportin in HCC cell lines.

RESULTS

Ferroportin expression in HCC tissue was significantly lower compared to PCLT and normal liver tissue (P <0.05). Moreover, ferroportin expression was related to liver cancer cell de-differentiation, the severity degree in TNM staging, Edmondson-Steiner grading, intrahepatic metastasis and portal vein invasion. In addition, high expression of ferroportin was observed in normal human liver cell lines L02 and HL7702, whereas weak positive expression and even negative expression of ferroportin were observed in HCC cell lines FOCUS, MHCC-97H, HepG2 and SMMC-7721. Furthermore, among the four kinds of HCC cell lines, the expression level of ferroportin was the lowest in MHCC-97H cells.

CONCLUSIONS

Ferroportin expression level declines along with the progression of liver cancer, suggesting that the reduction of ferroportin may serve as an important marker for poor HCC prognosis and as a new therapeutic target.

Molecular mechanisms of cognitive impairment in iron deficiency: alterations in brain-derived neurotrophic factor and insulin-like growth factor expression and function in the central nervous system

OBJECTIVE

The present review examines the relationship between iron deficiency and central nervous system (CNS) development and cognitive impairment, focusing on the cellular and molecular mechanisms related to the expression and function of growth factors, particularly the insulin-like growth factors I and II (IGF-I/II) and brain-derived neurotrophic factor (BDNF), in the CNS.

METHODS

Nutritional deficiencies are important determinants in human cognitive impairment. Among these, iron deficiency has the highest prevalence worldwide. Although this ailment is known to induce psychomotor deficits during development, the precise molecular and cellular mechanisms underlying these alterations have not been properly elucidated. This review summarizes the available information on the effect of iron deficiency on the expression and function of growth factors in the CNS, with an emphasis on IGF-I/II and BDNF.

RESULTS AND DISCUSSION

Recent studies have shown that specific growth factors, such as IGF-I/II and BDNF, have an essential role in cognition, particularly in processes involving learning and memory, by the activation of intracellular-signaling pathways involved in cell proliferation, differentiation, and survival. It is known that nutritional deficiencies promote reductions in systemic and CNS concentrations of growth factors, and that altered expression of these molecules and their receptors in the CNS leads to psychomotor and developmental deficits. Iron deficiency may induce these deficits by decreasing the expression and function of IGF-I/II and BDNF in specific areas of the brain.

Influence of iron status on risk of maternal or neonatal infection and on neonatal mortality with an emphasis on developing countries

Infection is a major cause of neonatal death in developing countries. This review investigates whether host iron status affects the risk of maternal and/or neonatal infection, potentially contributing to neonatal death, and summarizes the iron acquisition mechanisms described for pathogens causing stillbirth, preterm birth, and congenital infection. In vitro evidence shows that iron availability influences the severity and chronicity of infections that cause these negative outcomes of pregnancy. In vivo evidence is lacking, as relevant studies of maternal iron supplementation have not assessed the effect of iron status on the risk of maternal and/or neonatal infection. Reducing iron-deficiency anemia among women is beneficial and should improve the iron stores of babies; moreover, there is evidence that iron status in young children predicts the risk of malaria and, possibly, the risk of invasive bacterial diseases. Caution with maternal iron supplementation is indicated in iron-replete women who may be at high risk of exposure to infection, although distinguishing between iron-replete and iron-deficient women is currently difficult in developing countries, where a point-of-care test is needed. Further research is indicated to investigate the risk of infection relative to iron status in mothers and babies in order to avoid iron intervention strategies that may result in detrimental birth outcomes in some groups of women.

GDF15-mediated upregulation of ferroportin plays a key role in the development of hyperferritinemia in children with hemophagocytic lymphohistiocytosis

BACKGROUND

Growth differentiation factor 15 (GDF15), a divergent TGFβ superfamily, has recently been implicated in the modulation of iron homeostasis, acting as an upstream negative regulator of hepcidin, the key iron regulatory hormone produced primarily by hepatocytes. However, little is known about possible roles that GDF15 might play in the regulation of iron homeostasis and development of hyperferritinemia in children with hemophagocytic lymphohistiocytosis (HLH).

PROCEDURES

We compared serum GDF15 level and mRNA expressions of GDF15 and key molecules of iron metabolism, and made correlations between their expressions in children with HLH and control children.

RESULTS

Serum GDF15 level was remarkably higher in HLH group than that in controls, with median serum concentration of 1,700 and 260 pg/ml, respectively (P < 0.001). In addition, GDF15 mRNA was significantly upregulated but independent of hypoxia-inducible factor-mediated oxygen signaling pathway. More importantly, GDF15 induction was positively correlated to upregulation of ferroportin, the only cellular iron exporter, and to upregulation of ferritin heavy chain.

CONCLUSIONS

Our study suggests that GDF15 induction helps suppress further activation of macrophages in stressful physiologic states as HLH, and is intimately implicated in the development of hyperferritinemia by modulating the hepcidin-ferroportin axis, resulting in enhanced ferroportin-mediated iron efflux.

Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury

Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This review focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects.

Inflammation and diminished iron status: mechanisms and functional outcomes

PURPOSE OF REVIEW

To summarize recent findings regarding the effects of inflammation on iron (Fe) metabolism and to review studies detailing the influence of poor Fe status on physical and cognitive performance.

RECENT FINDINGS

Hepatic expression and release of hepcidin, a negative regulator of Fe status, is increased by the actions of the inflammatory cytokine interleukin-6. Inflammation associated with chronic disease, obesity, and exercise is associated with elevated interleukin-6 and hepcidin levels, which may result in diminished Fe status.

SUMMARY

Decrements in Fe status due to insufficient dietary Fe intake and/or the inflammatory response may degrade physical and cognitive performance. Future studies should clarify whether dietary or other therapeutic interventions to mitigate inflammation attenuate hepcidin-mediated declines in Fe status.

Acute acetaminophen intoxication leads to hepatic iron loading by decreased hepcidin synthesis

Acetaminophen (APAP), a major cause of acute liver injury in the Western world, is mediated by metabolism and oxidative stress. Recent studies have suggested a role for iron in potentiating APAP-induced liver injury although its regulatory mechanism is not completely understood. The current study was designed to unravel the iron-regulating pathways in mice after APAP-induced hepatotoxicity. Mice with severe injury showed a significant increase in liver iron concentration and oxidative stress. Concurrently, the plasma concentration of hepcidin, the key regulator in iron metabolism, and hepatic hepcidin antimicrobial peptide (Hamp) mRNA expression levels were significantly reduced. We showed that hepcidin transcription was inhibited via several hepcidin-regulating factors, including the bone morphogenetic protein/small mother against decapentaplegic (BMP/SMAD) pathway, CCAAT/enhancer-binding protein α (C/EBPα), and possibly also via erythropoietin (EPO). Downregulation of the BMP/SMAD signaling pathway was most likely caused by hypoxia-inducible factor 1α (HIF-1α), which was increased in mice with severe APAP-induced liver injury. HIF-1α stimulates cleaving of hemojuvelin, the cofactor of the BMP receptor, thereby blocking BMP-induced signaling. In addition, gene expression levels of C/ebpα were significantly reduced, and Epo mRNA expression levels were significantly increased after APAP intoxication. These factors are regulated through HIF-1α during oxidative stress and suggest that HIF-1α is a key modulator in reduced hepcidin transcription after APAP-induced hepatotoxicity. In conclusion, acute APAP-induced liver injury leads to activation of HIF-1α, which results in a downregulation in hepcidin expression through a BMP/SMAD signaling pathway and through C/EBPα inhibition. Eventually, this leads to hepatic iron loading associated with APAP cytotoxicity.

Diagnostic value of transferrin

Despite the growing interest in hepcidin and other relatively new biomarkers, guidelines and clinical pathways continue to recommend traditional markers, such as serum transferrin (Tf) and ferritin, as laboratory tests for the diagnostic evaluation of iron-related disorders. In this study, we aimed to critically evaluate the diagnostic role of Tf relying on the highest level of available evidence by a comprehensive literature search. The role of Tf in iron deficiency (ID) and iron overload (IO) syndrome as well as a risk marker was evaluated. The low accuracy of Tf and Tf saturation (TS) in the diagnosis and management of ID conditions does not permit definitively recommending their use, even if recently published guidelines still consider the TS investigation as a complementary test for ferritin. If a tissue IO is suspected, TS is often used, even if it may not be the best test for detecting this condition. Nevertheless, clinical guidelines strongly recommend the use of TS as a first-level test for performing genetic diagnosis of hereditary hemochromatosis. Recently reported data indicating elevated TS as a risk factor for diabetes mellitus, cancer, and total mortality, may provide useful additions to the debate over whether or not to screen for IO using TS.