Hepcidin and iron homeostasis

Metal dyshomeostasis and inflammation in Alzheimer's and Parkinson's diseases: possible impact of environmental exposures

A dysregulated metal homeostasis is associated with both Alzheimer's (AD) and Parkinson's (PD) diseases; AD patients have decreased cortex and elevated serum copper levels along with extracellular amyloid-beta plaques containing copper, iron, and zinc. For AD, a putative hepcidin-mediated lowering of cortex copper mechanism is suggested. An age-related mild chronic inflammation and/or elevated intracellular iron can trigger hepcidin production followed by its binding to ferroportin which is the only neuronal iron exporter, thereby subjecting it to lysosomal degradation. Subsequently raised neuronal iron levels can induce translation of the ferroportin assisting and copper binding amyloid precursor protein (APP); constitutive APP transmembrane passage lowers the copper pool which is important for many enzymes. Using in silico gene expression analyses, we here show significantly decreased expression of copper-dependent enzymes in AD brain and metallothioneins were upregulated in both diseases. Although few AD exposure risk factors are known, AD-related tauopathies can result from cyanobacterial microcystin and β-methylamino-L-alanine (BMAA) intake. Several environmental exposures may represent risk factors for PD; for this disease neurodegeneration is likely to involve mitochondrial dysfunction, microglial activation, and neuroinflammation. Administration of metal chelators and anti-inflammatory agents could affect disease outcomes.

Inflammation alters the expression of DMT1, FPN1 and hepcidin, and it causes iron accumulation in central nervous system cells

Inflammation and iron accumulation are present in a variety of neurodegenerative diseases that include Alzheimer's disease and Parkinson's disease. The study of the putative association between inflammation and iron accumulation in central nervous system cells is relevant to understand the contribution of these processes to the progression of neuronal death. In this study, we analyzed the effects of the inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) and of lipopolysaccharide on total cell iron content and on the expression and abundance of the iron transporters divalent metal transporter 1 (DMT1) and Ferroportin 1 (FPN1) in neurons, astrocytes and microglia obtained from rat brain. Considering previous reports indicating that inflammatory stimuli induce the systemic synthesis of the master iron regulator hepcidin, we identified brain cells that produce hepcidin in response to inflammatory stimuli, as well as hepcidin-target cells. We found that inflammatory stimuli increased the expression of DMT1 in neurons, astrocytes, and microglia. Inflammatory stimuli also induced the expression of hepcidin in astrocytes and microglia, but not in neurons. Incubation with hepcidin decreased the expression of FPN1 in the three cell types. The net result of these changes was increased iron accumulation in neurons and microglia but not in astrocytes. The data presented here establish for the first time a causal association between inflammation and iron accumulation in brain cells, probably promoted by changes in DMT1 and FPN1 expression and mediated in part by hepcidin. This connection may potentially contribute to the progression of neurodegenerative diseases by enhancing iron-induced oxidative damage.

Increased iron loading induces Bmp6 expression in the non-parenchymal cells of the liver independent of the BMP-signaling pathway

Bone morphogenetic protein 6 (BMP6) is an essential cytokine for the expression of hepcidin, an iron regulatory hormone secreted predominantly by hepatocytes. Bmp6 expression is upregulated by increased iron-levels in the liver. Both hepatocytes and non-parenchymal liver cells have detectable Bmp6 mRNA. Here we showed that induction of hepcidin expression in hepatocytes by dietary iron is associated with an elevation of Bmp6 mRNA in the non-parenchymal cells of the liver. Consistently, incubation with iron-saturated transferrin induces Bmp6 mRNA expression in isolated hepatic stellate cells, but not in hepatocytes. These observations suggest an important role of the non-parenchymal liver cells in regulating iron-homeostasis by acting as a source of Bmp6.

Striking the target in iron overload disorders

The liver, a major site of body iron stores, mediates key responses that preserve systemic iron homeostasis. In this issue of the JCI, Guo et al. demonstrate that administration of antisense oligonucleotides that reduce expression of Tmprss6, a hepatic protein that plays an essential role in maintaining iron balance, can attenuate disease severity in mouse models of human iron overload disorders. These data reveal the potential of novel TMPRSS6-targeted therapies for the treatment of clinical conditions such as hereditary hemochromatosis and β-thalassemia.

Iron regulatory proteins control a mucosal block to intestinal iron absorption

Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

Cellular catabolism of the iron-regulatory peptide hormone hepcidin

Hepcidin, a 25-amino acid peptide hormone, is the principal regulator of plasma iron concentrations. Hepcidin binding to its receptor, the iron exporter ferroportin, induces ferroportin internalization and degradation, thus blocking iron efflux from cells into plasma. The aim of this study was to characterize the fate of hepcidin after binding to ferroportin. We show that hepcidin is taken up by ferroportin-expressing cells in a temperature- and pH-dependent manner, and degraded together with its receptor. When Texas red-labeled hepcidin (TR-Hep) was added to ferroportin-GFP (Fpn-GFP) expressing cells, confocal microscopy showed co-localization of TR-Hep with Fpn-GFP. Using flow cytometry, we showed that the peptide was almost completely degraded by 24 h after its addition, but that lysosomal inhibitors completely prevented degradation of both ferroportin and hepcidin. In addition, using radio-labeled hepcidin and HPLC analysis we show that hepcidin is not recycled, and that only degradation products are released from the cells. Together these results show that the hormone hepcidin and its receptor ferroportin are internalized together and trafficked to lysosomes where both are degraded.

Low vitamin D levels increase anemia risk in Korean women

BACKGROUND

We assessed the impact of vitamin D on hemoglobin levels in Korean adults, considering gender and menopausal status.

METHODS

We analyzed 2528 men and 3258 women divided into quartiles of vitamin D from the Fifth Korean National Health and Nutrition Examination Survey 2010. Anemia was defined as a hemoglobin level of <13 g/dl in men and <12 g/dl in women.

RESULTS

Pre- and post-menopausal women in the lowest 25-hydroxyvitamin D group were at an increased risk of anemia, after adjusting for confounding factors (OR (95% CI); Premenopausal: Q1 (≥18.45 ng/ml), 1; Q2 (14.69-18.44 ng/ml), 1.120 (0.745, 1.683); Q3 (11.93-14.68 ng/ml), 1.427 (0.963, 2.116); and Q4 (≤11.92 ng/ml), 1.821 (1.240, 2.673); P=0.009; and Post: Q1 (≥22.04 ng/ml), 1; Q2 (16.92-22.03 ng/ml), 1.106 (0.697, 1.756); Q3 (13.37-16.91 ng/ml), 1.167 (0.740, 1.839); and Q4 (≤13.36 ng/ml), 1.583 (1.026, 2.447); P=0.038). In addition, pre- and post-menopausal women in the lower 25-hydroxyvitamin D group were at a higher risk of iron deficient anemia and anemia of inflammation. However, post-menopausal women did not show a higher risk of anemia with CKD (P=0.470). Men with the lowest 25-hydroxyvitamin D levels did not show a higher risk of anemia (P=0.528).

CONCLUSIONS

Vitamin D-deficient Korean women had a higher risk of anemia.

Intravenous iron in inflammatory bowel diseases

PURPOSE OF REVIEW

Anemia and iron deficiency are the most common extraintestinal complications of inflammatory bowel diseases (IBDs) and are often undertreated. We review the evidence on intravenous (i.v.) iron overcoming the limitations of oral iron in IBD.

RECENT FINDINGS

Recent reports demonstrate that i.v. iron is at least as effective, quicker, and better tolerated than oral iron. Moreover, experimental data confirm that oral and parenteral iron have divergent effects on intestinal mucosa: oral iron severely increasing inflammation. Observational and randomized studies prove that i.v. iron is not only effective but also well tolerated with no negative influence in the activity of IBD. A new formulation, iron carboxymaltose, which permits higher individual doses, has been shown more effective and less costly than standard iron sucrose. Another formulation, iron isomaltoside, shows promising in in-vitro and small clinical studies, but data from large trials are not available yet.

SUMMARY

Oral iron is not an ideal option for treating anemia and iron deficiency in IBD. i.v. iron should be preferred at least in five scenarios: intolerance to oral iron, severe anemia, failure of oral therapy, need for a quick recovery, and use of erythropoietin. Direct evidence in IBD patients not only confirms the effectiveness of i.v. iron, but also demonstrates that new, more convenient preparations probably will become the standard in the near future.

Iron status in patients with chronic heart failure

AIMS

The changes in iron status occurring during the course of heart failure (HF) and the underlying pathomechanisms are largely unknown. Hepcidin, the major regulatory protein for iron metabolism, may play a causative role. We investigated iron status in a broad spectrum of patients with systolic HF in order to determine the changes in iron status in parallel with disease progression, and to associate iron status with long-term prognosis.

METHODS AND RESULTS

Serum concentrations of ferritin, transferrin saturation (Tsat), soluble transferrin receptor (sTfR), and hepcidin were assessed as the biomarkers of iron status in 321 patients with chronic systolic HF [age: 61 ± 11 years, men: 84%, left ventricular ejection fraction: 31 ± 9%, New York Heart Association (NYHA) class: 72/144/87/18] at a tertiary cardiology centre and 66 age- and gender-matched healthy subjects. Compared with healthy subjects, asymptomatic HF patients had similar haematological status, but increased iron stores (evidenced by higher serum ferritin without distinct inflammation, P < 0.01) with markedly elevated serum hepcidin (P < 0.001). With increasing HF severity, patients in advanced NYHA classes had iron deficiency (ID) (reduced serum ferritin, low Tsat, high sTfR), iron-restricted erythropoiesis (reduced haemoglobin, high red cell distribution width), and inflammation (high serum high-sensitivity-C-reactive protein and interleukin 6), which was accompanied by decreased circulating hepcidin (all P < 0.001). In multivariable Cox models, low hepcidin was independently associated with increased 3-year mortality among HF patients (P < 0.001).

CONCLUSIONS

Increased level of circulating hepcidin characterizes an early stage of HF, and is not accompanied by either anaemia or inflammation. The progression of HF is associated with the decline in circulating hepcidin and the development of ID. Low hepcidin independently relates to unfavourable outcome.

Serum prohepcidin levels are lower in patients with atrophic gastritis

Background/Aim. Hepcidin, an iron regulatory hormone, is increased in response to inflammation and some infections. We investigated the relationships among serum prohepcidin, iron status, Helicobacter pylori infection status, and the presence of gastric mucosal atrophy. Methods. Seventy subjects undergoing esophagogastroduodenoscopy underwent multiple gastric biopsies, and the possibility of H. pylori infection and the degree of endoscopic and histologic gastritis were investigated. In all subjects, serum prohepcidin and iron parameters were evaluated. Results. No correlations were observed between serum prohepcidin levels and the other markers of anemia, such as hemoglobin, serum iron, ferritin, and total iron binding capacity. Serum prohepcidin levels were not significantly different between the H. pylori-positive group and the H. pylori-negative group. Serum prohepcidin levels in atrophic gastritis patients were significantly lower than those in subjects without atrophic gastritis irrespective of H. pylori infection. Conclusion. Serum prohepcidin levels were not altered by H. pylori infection. Serum prohepcidin levels decrease in patients with atrophic gastritis, irrespective of H. pylori infection. It suggests that hepcidin may decrease due to gastric atrophy, a condition that causes a loss of hepcidin-producing parietal cells. Further investigations with a larger number of patients are necessary to substantiate this point.

Hepcidin level predicts hemoglobin concentration in individuals undergoing repeated phlebotomy

Dietary iron absorption is regulated by hepcidin, an iron regulatory protein produced by the liver. Hepcidin production is regulated by iron stores, erythropoiesis and inflammation, but its physiology when repeated blood loss occurs has not been characterized. Hepcidin was assayed in plasma samples obtained from 114 first-time/reactivated (no blood donations in preceding 2 years) female donors and 34 frequent (≥3 red blood cell donations in preceding 12 months) male donors as they were phlebotomized ≥4 times over 18-24 months. Hepcidin levels were compared to ferritin and hemoglobin levels using multivariable repeated measures regression models. Hepcidin, ferritin and hemoglobin levels declined with increasing frequency of donation in the first-time/reactivated females. Hepcidin and ferritin levels correlated well with each other (Spearman's correlation of 0.74), but on average hepcidin varied more between donations for a given donor relative to ferritin. In a multivariable repeated measures regression model the predicted inter-donation decline in hemoglobin varied as a function of hepcidin and ferritin; hemoglobin was 0.51 g/dL lower for subjects with low (>45.7 ng/mL) or decreasing hepcidin and low ferritin (>26 ng/mL), and was essentially zero for other subjects including those with high (>45.7 ng/mL) or increasing hepcidin and low ferritin (>26 ng/mL) levels (P<0.001). In conclusion, hepcidin levels change rapidly in response to dietary iron needed for erythropoiesis. The dynamic regulation of hepcidin in the presence of a low levels of ferritin suggests that plasma hepcidin concentration may provide clinically useful information about an individual's iron status (and hence capacity to tolerate repeated blood donations) beyond that of ferritin alone. Clinicaltrials.gov identifier: NCT00097006.

PGC-1α regulates hepatic hepcidin expression and iron homeostasis in response to inflammation

Systemic iron homeostasis is finely regulated by the liver through synthesis of the peptide hormone hepcidin (HAMP), which plays an important role in duodenal iron absorption and macrophage iron release. Clinical investigations have shown that chronic and low-grade inflammation leads to the increase of serum HAMP levels and the development of various diseases such as anemia of inflammation. However, gaps remain to fully elucidate the mechanism linking inflammation and iron dysregulation. Here we show that although inflammatory stimuli increase hepatic HAMP expression and cause systemic iron deficiency in mice, they inhibit the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a transcriptional coactivator actively involved in metabolic regulation. Liver-specific overexpression of PGC-1α antagonizes lipopolysaccharide-induced HAMP expression and alleviates various pathophysiological changes similar to anemia of inflammation. Consistently, overexpression of PGC-1α in HepG2 or HuH7 cells also suppresses HAMP expression and reduces iron accumulation. In contrast, knockdown of PGC-1α exaggerates LPS-induced HAMP expression and iron dysregulation. At the molecular level, PGC-1α suppresses HAMP transcription via the interaction with hepatocyte nuclear factor 4α. In addition, PGC-1α is present near hepatocyte nuclear factor 4α-binding site on the proximal HAMP promoter and turns the chromatin structure into an inactive state. Our data suggest a critical role for PGC-1α in the regulation of hepatic HAMP expression and iron homeostasis under inflammatory circumstances.

Dynamics of anemia in relation to parasitic infections, micronutrient status, and increasing age in South-Central Côte d'Ivoire

BACKGROUND

Parasitic diseases (eg, malaria and helminthiases) exert enormous burdens on public health and social well-being. Moreover, parasitic infections are important causes of anemia in tropical Africa, exacerbated by lack of a diversified diet and inflammatory and genetic diseases. There is a paucity of longitudinal studies monitoring the dynamics of anemia in relation to the aforementioned parameters.

METHODS

We designed a 14-month prospective longitudinal study in 3 cohorts (ie, infants aged 6-23 months, children aged 6-8 years, and women aged 15-25 years) in the Taabo health demographic surveillance system located in south-central Côte d'Ivoire. Parasitological, hematological, and micronutrient data were obtained from repeated cross-sectional surveys, utilizing standardized, quality-controlled methods.

RESULTS

We found that young age, Plasmodium and Schistosoma infections, cellular iron deficiency, and stunting were significantly negatively associated with hemoglobin concentration. Moreover, iron status biomarkers (ie, ferritin and soluble transferrin receptor) were significantly associated with inflammatory parameters.

CONCLUSIONS

Based on our results, effective prevention and control measures that target parasitic diseases and iron deficiency are needed. These measures might include the distribution of long-lasting insecticidal nets, intermittent preventive treatment for malaria, regular anthelmintic drug administration, and improved intake of bioavailable iron, coupled with health and nutritional education and improved hygiene, water, and sanitation.

HCV and oxidative stress in the liver

Hepatitis C virus (HCV) is the etiological agent accounting for chronic liver disease in approximately 2-3% of the population worldwide. HCV infection often leads to liver fibrosis and cirrhosis, various metabolic alterations including steatosis, insulin and interferon resistance or iron overload, and development of hepatocellular carcinoma or non-Hodgkin lymphoma. Multiple molecular mechanisms that trigger the emergence and development of each of these pathogenic processes have been identified so far. One of these involves marked induction of a reactive oxygen species (ROS) in infected cells leading to oxidative stress. To date, markers of oxidative stress were observed both in chronic hepatitis C patients and in various in vitro systems, including replicons or stable cell lines expressing viral proteins. The search for ROS sources in HCV-infected cells revealed several mechanisms of ROS production and thus a number of cellular proteins have become targets for future studies. Furthermore, during last several years it has been shown that HCV modifies antioxidant defense mechanisms. The aim of this review is to summarize the present state of art in the field and to try to predict directions for future studies.

Cellular iron metabolism in prognosis and therapy of breast cancer

Despite many recent advances, breast cancer remains a clinical challenge. Current issues include improving prognostic evaluation and increasing therapeutic options for women whose tumors are refractory to current frontline therapies. Iron metabolism is frequently disrupted in breast cancer, and may offer an opportunity to address these challenges. Iron enhances breast tumor initiation, growth and metastases. Iron may contribute to breast tumor initiation by promoting redox cycling of estrogen metabolites. Up-regulation of iron import and down-regulation of iron export may enable breast cancer cells to acquire and retain excess iron. Alterations in iron metabolism in macrophages and other cells of the tumor microenvironment may also foster breast tumor growth. Expression of iron metabolic genes in breast tumors is predictive of breast cancer prognosis. Iron chelators and other strategies designed to limit iron may have therapeutic value in breast cancer. The dependence of breast cancer on iron presents rich opportunities for improved prognostic evaluation and therapeutic intervention.

Study to establish the role of JAK2 and SMAD1/5/8 pathways in the inhibition of hepcidin by polysaccharides from Angelica sinensis

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica sinensis polysaccharide (ASP) is one of the major active ingredients in Angelica sinensis (Oliv.) Diels. This traditional Chinese medicine has been used for thousands of years for treating gynecological diseases.

AIM OF THE STUDY

Previous studies have suggested that ASP from the roots of Angelica sinensis (Oliv.) Diels suppresses hepcidin expression, but the underlying molecular mechanisms are not known. The present study was designed to establish the role of the janus-kinases 2 (JAK2) and son of mothers against decapentaplegic 1/5/8 (SMAD1/5/8) pathways in the inhibition of hepcidin by polysaccharides from Angelica sinensis in normal rats.

MATERIALS AND METHODS

ASP was administered orally (0.3, 0.6 and 1.2g/kg body weight) to male Sprague-Dawley rats every day for 20 days. Intraperitoneal injections of recombinant human erythropoietin (rhEPO; 800 and 2000U/kg body weight) were given to the positive control group every day for 3 days. After administration, hepcidin levels, blood parameters, serum iron status and non-heme iron concentrations in the liver were examined. Western blot analyses were used to investigate the expression of five relevant signaling proteins in the liver.

RESULTS

RhEPO injection significantly stimulated erythropoiesis and expression of the serum transferrin receptor (sTfR), and decreased serum iron status and non-heme iron concentrations in the liver. However, blood parameters barely changed in the ASP groups. sTfR, serum iron, and liver iron levels altered only in the ASP high-dose group (1.2g/kg body weight). rhEPO and ASP significantly reduced hepcidin expression by inhibiting the expression of phospho-SMAD1/5/8 and JAK2 in the liver, but not through transmembrane protease serine 6 (TMPRSS6) and extracellular signal-regulated kinase 1/2 (ERK1/2).

CONCLUSIONS

These data suggested that ASP can interrupt the JAK2 and SMAD1/5/8 pathways, which eventually results in lower expression of hepcidin.

Anaemia in inflammatory rheumatic diseases

Anaemia is frequently observed in patients with inflammatory rheumatic diseases. Depending on its severity, anaemia negatively affects cardiovascular performance, physical activity and the quality of life of patients. However, anaemia is considered to be a symptom of the underlying inflammatory disease and, thus, neglected as a complex medical condition that warrants specific diagnosis and treatment. Although inflammation-induced alterations in iron homeostasis and erythropoiesis have a dominant role in the pathogenesis of this type of anaemia, multiple other factors such as chronic blood loss, haemolysis, disease and treatment-associated adverse effects or vitamin deficiencies can also take part in the development of anaemia. Accordingly, the prevalence of anaemia is positively associated with the severity of the underlying disease. This Review will summarize epidemiological data on anaemia in inflammatory rheumatic diseases, along with a detailed description of underlying pathophysiological pathways, available diagnostic tools and practical diagnostic strategies. Discussion of established and newly emerging treatment regimens, as well as the need for further research in this clinically relevant field, will also be included.

F-box and leucine-rich repeat protein 5 (FBXL5) is required for maintenance of cellular and systemic iron homeostasis

Maintenance of cellular iron homeostasis requires post-transcriptional regulation of iron metabolism genes by iron regulatory protein 2 (IRP2). The hemerythrin-like domain of F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, senses iron and oxygen availability and facilitates IRP2 degradation in iron replete cells. Disruption of the ubiquitously expressed murine Fbxl5 gene results in a failure to sense increased cellular iron availability, accompanied by constitutive IRP2 accumulation and misexpression of IRP2 target genes. FBXL5-null mice die during embryogenesis, although viability is restored by simultaneous deletion of the IRP2, but not IRP1, gene. Mice containing a single functional Fbxl5 allele behave like their wild type littermates when fed an iron-sufficient diet. However, unlike wild type mice that manifest decreased hematocrit and hemoglobin levels when fed a low-iron diet, Fbxl5 heterozygotes maintain normal hematologic values due to increased iron absorption. The responsiveness of IRP2 to low iron is specifically enhanced in the duodena of the heterozygotes and is accompanied by increased expression of the divalent metal transporter-1. These results confirm the role of FBXL5 in the in vivo maintenance of cellular and systemic iron homeostasis and reveal a privileged role for the intestine in their regulation by virtue of its unique FBXL5 iron sensitivity.

Estrogen regulates iron homeostasis through governing hepatic hepcidin expression via an estrogen response element

Iron is essential for the human being, involving in oxygen transport, energy metabolism and DNA synthesis. Iron homeostasis is tightly governed by the hepcidin-ferroportin axis, of which hepcidin is the master regulator. Excess iron is associated with various diseases including osteopenia and osteoporosis, which are closely related to the alternation of the endogenous estrogen level. To verify the biological effect of estrogen on iron metabolism, we established a mouse model of estrogen deficiency by ovariectomy. We demonstrated that the hemoglobin content and serum iron level decreased, whereas the tissue iron level in liver and spleen increased in the ovariectomized mice. Moreover, the transcription of hepatic hepcidin was elevated in ovariectomized mice compared to the control mice. We further demonstrated that there was an estrogen response element (ERE) in the promoter region of the hepcidin gene. The assay using the luciferase reporter system confirmed the existence of a functional ERE in the hepcidin promoter, as the estradiol treatment reduced hepcidin expression in cells transfected with ERE-intact construct, with no response to estradiol in cells transfected with ERE-devoid construct. In conclusion, estrogen greatly contributes to iron homeostasis by regulating hepatic hepcidin expression directly through a functional ERE in the promoter region of hepcidin gene. These findings might help build a better understanding towards the etiology of postmenopausal osteoporosis accompanied by excess tissue iron (such as iron retention of osteoclasts in bone) under estrogen deficiency.

Minihepcidins prevent iron overload in a hepcidin-deficient mouse model of severe hemochromatosis

The deficiency of hepcidin, the hormone that controls iron absorption and its tissue distribution, is the cause of iron overload in nearly all forms of hereditary hemochromatosis and in untransfused iron-loading anemias. In a recent study, we reported the development of minihepcidins, small drug-like hepcidin agonists. Here we explore the feasibility of using minihepcidins for the prevention and treatment of iron overload in hepcidin-deficient mice. An optimized minihepcidin (PR65) was developed that had superior potency and duration of action compared with natural hepcidin or other minihepcidins, and favorable cost of synthesis. PR65 was administered by subcutaneous injection daily for 2 weeks to iron-depleted or iron-loaded hepcidin knockout mice. PR65 administration to iron-depleted mice prevented liver iron loading, decreased heart iron levels, and caused the expected iron retention in the spleen and duodenum. At high doses, PR65 treatment also caused anemia because of profound iron restriction. PR65 administration to hepcidin knockout mice with pre-existing iron overload had a more moderate effect and caused partial redistribution of iron from the liver to the spleen. Our study demonstrates that minihepcidins could be beneficial in iron overload disorders either used alone for prevention or possibly as adjunctive therapy with phlebotomy or chelation.

Rosiglitazone improves survival and hastens recovery from pancreatic inflammation in obese mice

Obesity increases severity of acute pancreatitis (AP) by unclear mechanisms. We investigated the effect of the PPAR-gamma agonist rosiglitazone (RGZ, 0.01% in the diet) on severity of AP induced by administration of IL-12+ IL-18 in male C57BL6 mice fed a low fat (LFD) or high fat diet (HFD), under the hypothesis that RGZ would reduce disease severity in HFD-fed obese animals. In both LFD and HFD mice without AP, RGZ significantly increased body weight and % fat mass, with significant upregulation of adiponectin and suppression of erythropoiesis. In HFD mice with AP, RGZ significantly increased survival and hastened recovery from pancreatic inflammation, as evaluated by significantly improved pancreatic histology, reduced saponification of visceral adipose tissue and less severe suppression of erythropoiesis at Day 7 post-AP. This was associated with significantly lower circulating and pancreas-associated levels of IL-6, Galectin-3, osteopontin and TIMP-1 in HFD + RGZ mice, particularly at Day 7 post-AP. In LFD mice with AP, RGZ significantly worsened the degree of intrapancreatic acinar and fat necrosis as well as visceral fat saponification, without affecting other parameters of disease severity or inflammation. Induction of AP lead to major suppression of adiponectin levels at Day 7 in both HFD and HFD + RGZ mice. In conclusion, RGZ prevents development of severe AP in obese mice even though it significantly increases adiposity, indicating that obesity can be dissociated from AP severity by improving the metabolic and inflammatory milieu. However, RGZ worsens selective parameters of AP severity in LFD mice.

Lactoferrin, a bird’s eye view

Lactoferrin is an abundant iron-binding protein in milk. This 80 kDa bilobal glycoprotein is also present in several other secreted bodily fluids, as well as in the secondary granules of neutrophils. The potent iron-binding properties of lactoferrin can locally create iron deficiency, and this is an important factor in host defense as it prevents bacteria from growing and forming biofilms. In addition to having antibacterial activity, lactoferrin is now known to have a long list of other beneficial biological properties. It has direct antiviral, antifungal, and even some anticancer activities. It can also promote wound healing and bone growth, or it can act as an iron carrier. Moreover, lactoferrin displays a cytokine-like “alarmin” activity, and it activates the immune system. Simultaneously, it can bind endotoxin (lipopolysaccharide), and in doing so, it modulates the activity of the host immune response. The majority of these intriguing biological activities reside in the unique positively charged N-terminal region of the protein. Interestingly, several peptides, which retain many of the beneficial activities, can be released from this region of lactoferrin. An isoform of the human protein, known as delta-lactoferrin, is expressed inside many cells, where it acts as a transcription factor. Lactoferrin purified from human and bovine milk have very similar but not completely identical properties. Lactoferrin receptors have been identified on the surface of various cells, and some of these can bind both the human and the bovine protein. Because of the extensive health-promoting effects of lactoferrin, there has been considerable interest in the use of bovine or human lactoferrin as a “protein nutraceutical” or as a therapeutic protein. When lactoferrin is used as a “biologic drug”, it seems to be orally active in contrast to most other therapeutic proteins.

High hepcidin level accounts for the nigral iron accumulation in acute peripheral iron intoxication rats

Hepcidin is considered to be a circulatory hormone and a major mechanism regulating iron homeostasis. Our previous publication revealed that acute iron intoxication induced iron deposit and dopaminergic neuron degeneration in the substantia nigra (SN) of a rat model. However, whether and how hepcidin functions in this nigral iron accumulation has not been elucidated. In the present study, we observed a decreased of FPN1 protein level in the SN triggered by peripheral iron overload within 4 h, which correlated with a high hepcidin level. To further investigate the role of intracellular hepcidin under iron overload circumstances, we assessed the expression of hepcidin mRNA and FPN1 protein in vitro. We observed that hepcidin mRNA level was up-regulated and FPN1 protein level was down-regulated in MES23.5 dopaminergic cells in a period of 4h incubation with iron. Both in pCMV-XL4-hepcidin transfected and hepcidin-treated cells, decreased FPN1 protein levels were observed. Our data provide direct evidence that the role for intracellular hepcidin generated in the SN is particularly relevant to restrict iron release by down-regulation FPN1 expression in this region, thus an important contributor to the abnormal iron deposit occurred at an early stage in conditions of peripheral iron intoxication.