Hepcidin antagonists for potential treatments of disorders with hepcidin excess

5noThe discovery of hepcidin clarified the basic mechanism of the control of systemic iron homeostasis. Hepcidin is mainly produced by the liver as a propeptide and processed by furin into the mature active peptide. Hepcidin binds ferroportin, the only cellular iron exporter, causing the internalization and degradation of both. Thus hepcidin blocks iron export from the key cells for dietary iron absorption (enterocytes), recycling of hemoglobin iron (the macrophages) and the release of storage iron from hepatocytes, resulting in the reduction of systemic iron availability. The BMP/HJV/SMAD pathway is the major regulator of hepcidin expression that responds to iron status. Also inflammation stimulates hepcidin via the IL6/STAT3 pathway with a support of an active BMP/HJV/SMAD pathway. In some pathological conditions hepcidin level is inadequately elevated and reduces iron availability in the body, resulting in anemia. These conditions occur in the genetic iron refractory iron deficiency anemia and the common anemia of chronic disease (ACD) or anemia of inflammation. Currently, there is no definite treatment for ACD. Erythropoiesis-stimulating agents and intravenous iron have been proposed in some cases but they are scarcely effective and may have adverse effects. Alternative approaches aimed to a pharmacological control of hepcidin expression have been attempted, targeting different regulatory steps. They include hepcidin sequestering agents (antibodies, anticalins, and aptamers), inhibitors of BMP/SMAD or of IL6/STAT3 pathway or of hepcidin transduction (siRNA/shRNA) or ferroportin stabilizers. In this review we summarized the biochemical interactions of the proteins involved in the BMP/HJV/SMAD pathway and its natural inhibitors, the murine and rat models with high hepcidin levels currently available and finally the progresses in the development of hepcidin antagonists, with particular attention to the role of heparins and heparin sulfate proteoglycans in hepcidin expression and modulation of the BMP6/SMAD pathway.openopenMaura, Poli; Michela, Asperti; Paola, Ruzzenenti; Maria, Regoni; Paolo, ArosioPoli, Maura; Asperti, Michela; Ruzzenenti, Paola; Regoni, Maria; Arosio, Paol

Hepatic heparan sulfate is a master regulator of hepcidin expression and iron homeostasis in human hepatocytes and mice.

Hepcidin is a liver-derived peptide hormone that controls systemic iron homeostasis. Its expression is regulated by the bone morphogenetic protein 6 (BMP6)/SMAD1/5/8 pathway and by the proinflammatory cytokine interleukin 6 (IL6). Proteoglycans that function as receptors of these signaling proteins in the liver are commonly decorated by heparan sulfate, but the potential role of hepatic heparan sulfate in hepcidin expression and iron homeostasis is unclear. Here, we show that modulation of hepatic heparan sulfate significantly alters hepcidin expression and iron metabolism both in vitro and in vivo Specifically, enzymatic removal of heparan sulfate from primary human hepatocytes, CRISPR/Cas9 manipulation of heparan sulfate biosynthesis in human hepatoma cells, or pharmacological manipulation of heparan sulfate-protein interactions using sodium chlorate or surfen dramatically reduced baseline and BMP6/SMAD1/5/8-dependent hepcidin expression. Moreover inactivation of the heparan sulfate biosynthetic gene N-deacetylase and N-sulfotransferase 1 (Ndst1) in murine hepatocytes (Ndst1 f/f AlbCre +) reduced hepatic hepcidin expression and caused a redistribution of systemic iron, leading to iron accumulation in the liver and serum of mice. Manipulation of heparan sulfate had a similar effect on IL6-dependent hepcidin expression in vitro and suppressed IL6-mediated iron redistribution induced by lipopolysaccharide in vivo These results provide compelling evidence that hepatocyte heparan sulfate plays a key role in regulating hepcidin expression and iron homeostasis in mice and in human hepatocytes

Biochemical, Biophysical and Functional Characterization of an Insoluble Iron Containing Hepcidin-Ferritin Chimeric Monomer Assembled Together with Human Ferritin H/L Chains at Different Molar Ratios

Hepcidin and ferritin are key proteins of iron homeostasis in mammals. In this study, we characterize a chimera by fusing camel hepcidin to a human ferritin H-chain to verify if it retained the properties of the two proteins. The construct (HepcH) is expressed in E. coli in an insoluble and iron-containing form. To characterize it, the product was incubated with ascorbic acid and TCEP to reduce and solubilize the iron, which was quantified with ferrozine. HepcH bound approximately five times more iron than the wild type human ferritin, due to the presence of the hepcidin moiety. To obtain a soluble and stable product, the chimera was denatured and renatured together with different amounts of L-ferritin of the H-chain in order to produce 24-shell heteropolymers with different subunit proportions. They were analyzed by denaturing and non-denaturing PAGE and by mass spectroscopy. At the 1:5 ratio of HepcH to H- or L-ferritin, a stable and soluble molecule was obtained. Its biological activity was verified by its ability to both bind specifically cell lines that express ferroportin and to promote ferroportin degradation. This chimeric molecule showed the ability to bind both mouse J774 macrophage cells, as well as human HepG2 cells, via the hepcidin-ferroportin axis. We conclude that the chimera retains the properties of both hepcidin and ferritin and might be exploited for drug delivery

Fatal Pulmonary Hypertension and Right-Sided Congestive Heart Failure in a Kitten Infected with Aelurostrongylus abstrusus

Aelurostrongylus abstrusus is considered the most important respiratory nematode of domestic cats worldwide. This parasite inhabits the alveoli, alveolar ducts, and bronchioles and causes a subacute to chronic respiratory clinical disease. Clinical signs may occur in domestic cats of any age, though they are more often described in young animals. Physical examination, echocardiography, thoracic radiography, pulmonary and cardiac pathological findings, classical, and molecular parasitological analysis of a six-month-old kitten referred at the Veterinary Teaching Hospital of the University of Pisa (Italy) led to a diagnosis of parasitic bronchopneumonia caused by A. abstrusus, which was complicated by severe pulmonary hypertension (PH) and right-sided congestive heart failure (R-CHF) that caused the death of the animal. Cases of reversible PH associated with A. abstrusus infection have been seldom reported in cats. This is the first report of fatal PH and R-CHF in a kitten with clinical aelurostrongylosis

Heparanase overexpression reduces hepcidin expression, affects iron homeostasis and alters the response to inflammation

Hepcidin is the key regulator of systemic iron availability that acts by controlling the degradation of the iron exporter ferroportin. It is expressed mainly in the liver and regulated by iron, inflammation, erythropoiesis and hypoxia. The various agents that control its expression act mainly via the BMP6/SMAD signaling pathway. Among them are exogenous heparins, which are strong hepcidin repressors with a mechanism of action not fully understood but that may involve the competition with the structurally similar endogenous Heparan Sulfates (HS). To verify this hypothesis, we analyzed how the overexpression of heparanase, the HS degrading enzyme, modified hepcidin expression and iron homeostasis in hepatic cell lines and in transgenic mice. The results showed that transient and stable overexpression of heparanase in HepG2 cells caused a reduction of hepcidin expression and of SMAD5 phosphorylation. Interestingly, the clones showed also altered level of TfR1 and ferritin, indices of a modified iron homeostasis. The heparanase transgenic mice showed a low level of liver hepcidin, an increase of serum and liver iron with a decrease in spleen iron content. The hepcidin expression remained surprisingly low even after treatment with the inflammatory LPS. The finding that modification of HS structure mediated by heparanase overexpression affects hepcidin expression and iron homeostasis supports the hypothesis that HS participate in the mechanisms controlling hepcidin expression

Production and characterization of functional recombinant hybrid heteropolymers of camel hepcidin and human ferritin H and L chains

This article has been accepted for publication in Protein Engineering design and Selection Published by Oxford University Press.Hepcidin is a liver-synthesized hormone that plays a central role in the regulation of systemic iron homeostasis. To produce a new tool for its functional properties the cDNA coding for camel hepcidin-25 was cloned at the 5’end of human FTH sequence into the pASK-IBA43plus vector for expression in Escherichia coli. The recombinant fusion hepcidin–ferritin-H subunit was isolated as an insoluble iron-containing protein. When alone it did not refold in a 24-mer ferritin molecule, but it did when renatured together with H- or L-ferritin chains. We obtained stable ferritin shells exposing about 4 hepcidin peptides per 24-mer shell. The molecules were then reduced and re-oxidized in a controlled manner to allow the formation of the proper hepcidin disulfide bridges. The functionality of the exposed hepcidin was confirmed by its ability to specifically bind the mouse macrophage cell line J774 that express ferroportin and to promote ferroportin degradation. This chimeric protein may be useful for studying the hepcidin–ferroportin interaction in cells and also as drug-delivery agent.This work is partially financed by the Laboratory of Protein Engineering and Bioactive Molecules (LIP-MB) and the Doctoral School of the National Institute of Applied Sciences and Technology (INSAT-Tunis) – University of Carthage

3D extracellular matrix derived model of alveolar rhabdomyosarcoma

INTRODUCTION: Rhabdomyosarcoma is the most common soft tissue sarcoma in childhood, among the subtypes the Alveolar (ARMS) is the more aggressive with a higher tendency to metastasize [1]. Integrins are a class of transmembrane adhesion molecules that mediate survival, differentiation, migration and differentiation [2]. Here we investigate the role of integrins in ARMS metastatic migration in an engineered 3D scaffold. METHODS: ARMS xenografts are obtained from subcutaneous injection of RH30 cells in immunodeficient mice. Composition of the ECM is determined by proteomic analysis. The main components of the ECM are used to enrich a 3D collagen scaffold cultured in a perfusion bioreactor. Cells are analyzed by qPCR for the expression of a panel of integrins. Presence of the protein is confirmed by flow cytometry immunofluorescence. MMPs expression is evaluated by zymography. RESULTS: Verified the expression of human and ARMS marker and typical tumor morphology in xenografts, they are processed for proteomic analysis. Proteomic data analysis is currently under investigation. Preliminary data culturing RH30 cells in 3D bioreactor show upregulation of ITG5 and CXCR4 receptor compared to 2D condition. Localization and quantification at protein level will be assessed respectively by immunofluorescence and cytofluorimetry. Expression of MMP-9 and MMP-2 has been assessed by zymography comparing the expression of these MMPs in 2D vs 3D bioreactor and RH30 isolated from the xenograft. DISCUSSION & CONCLUSIONS: Preliminary data on ITG expression show that in 3D scaffold the expression of ITG5 and CXCR4 is upregulated. In parallel the active form of MMP-2 is more present in 3D models compared to 2D. Other groups reported a mechanical interaction between ITG5 and MMP-2 [3]. This interaction will be studied in a more representative engineered 3D scaffold to shed light on the complex interaction between ECM and metastatic progression

Patient safety in the eyes of aspiring healthcare professionals: a systematic review of their attitudes

A culture of safety is important for the delivery of safe, high-quality care, as well as for healthcare providers' wellbeing. This systematic review aimed to describe and synthesize the literature on patient safety attitudes of the next generation of healthcare workers (health professional students, new graduates, newly registered health professionals, resident trainees) and assess potential differences in this population related to years of study, specialties, and gender. We screened four electronic databases up to 20 February 2020 and additional sources, including weekly e-mailed search alerts up to 18 October 2020. Two independent reviewers conducted the search, study selection, quality rating, data extraction, and formal narrative synthesis, involving a third reviewer in case of dissent. We retrieved 6606 records, assessed 188 full-texts, and included 31 studies. Across articles, healthcare students and young professionals showed overwhelmingly positive patient safety attitudes in some areas (e.g., teamwork climate, error inevitability) but more negative perceptions in other domains (e.g., safety climate, disclosure responsibility). Women tend to report more positive attitudes. To improve safety culture in medical settings, health professions educators and institutions should ensure education and training on patient safety

"If you can't control the wind, adjust your sail": tips for post-pandemic benefit finding from young adults living with multiple sclerosis. A qualitative study

The COVID-19 outbreak has impacted the wellbeing of people worldwide, potentially increasing maladaptive psychological responses of vulnerable populations. Although young adults with multiple sclerosis (yawMS) might be at greater risk of developing psychological distress linked to the pandemic, they might also be able to adapt to stress and find meaning in adverse life events. The aim of the present study was to explore benefit finding in response to the pandemic in a sample of yawMS. As part of a larger project, data were collected using a cross-sectional, web-based survey. Benefit finding was analysed using a qualitative thematic approach; descriptive and inferential statistics were performed to describe the sample and compare sub-groups. Out of 247 respondents with mostly relapsing-remitting MS, 199 (31.9 \ub1 6.97 years) reported at least one benefit. Qualitative analysis showed that during the pandemic yawMS found benefits related to three themes: personal growth, relational growth, and existential growth. No differences in benefit finding were found between age sub-groups (18-30 vs. 31-45). Participants reported a wide range of benefits, some of which seem to be specific to MS or the pandemic. Results have been transformed into tips to be introduced in clinical practice to promote resilience in yawMS through meaning making