[Show abstract][Hide abstract] ABSTRACT: Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS) optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter.
[Show abstract][Hide abstract] ABSTRACT: Fiber Evanescent Wave Spectroscopy (FEWS) is an efficient way to collect optical spectra in situ, in real time and even, hopefully, in vivo. Thanks to selenide glass fibers, it is possible to get such spectra over the whole mid-infrared range from 2 to 12 μm. This working window gives access to the fundamental vibration band of most of biological molecules. Moreover selenide glasses are stable and easy to handle, and it is possible to shape the fiber and create a tapered sensing head to drastically increase the sensitivity. Within the past decades, numerous multi-disciplinary studies have been conducted in collaboration with the City Hospital of Rennes. Clinical trials have provided very promising results in biology and medicine which have led to the creation in 2011 of the DIAFIR Company dedicated to the commercialization of fiber-based infrared biosensors. In addition, new glasses based on tellurium only have been recently developed, initially in the framework of the Darwin mission led by the European Space Agency (ESA). These glasses transmit light further into the far-infrared and could also be very useful for medical applications in the near future. Indeed, they permit to reach the vibrational bands of biomolecules laying from 12 to 16 μm where selenide glasses do not transmit light anymore. However, while Se is a very good glass former, telluride glasses tend to crystallize easily due to the metallic nature of Te bonds. Hence, further work is under way to stabilize the glass composition for fibers drawing and to lower the optical losses for improving their sensitivity as bio-sensors.
[Show abstract][Hide abstract] ABSTRACT: To selectively target tumor cells expressing an overactive Polyamine Transport System (PTS), we designed, synthesized and evaluated the biological activity of a new generation of iron chelators, derived from the lead compound HQ1-44, which we named Quilamines II. The structures of four new antiproliferative agents were developed. They differ in the size of the linker (HQ0-44 and HQ2-44) or in the nature of the linker (HQCO-44 and HQCS-44) between a hydroxyquinoline moiety (HQ) and a homospermidine (44) chain, the best polyamine vector. The Quilamines II were obtained after 6 to 9 steps by Michael addition, peptide linkage and reductive amination or by using the Willgerodt-Kindler reaction. The biological evaluation of these second-generation Quilamines showed that modifying the size of the linker increased the selectivity of these compounds for the PTS. In addition, measurement of the toxicity of Quilamines HQ0-44 and HQ2-44 highlighted their marked antiproliferative nature on several cancerous cell lines as well as a differential activity on non-transformed cells (fibroblasts). In contrast, Quilamines HQCO-44 and HQCS-44 presented low selectivity for the PTS, probably due to a loss of electrostatic interaction. We also demonstrated that the HCT116 cell line, originating from a human colon adenocarcinoma, was the most responsive to the various Quilamines. As deduced from the calcein and HVA assays, the higher iron chelating capacity of HQ1-44 could explain its higher antiproliferative efficiency.
[Show abstract][Hide abstract] ABSTRACT: Identification of new players in iron metabolism, such as hepcidin, which regulates ferroportin and divalent metal transporter 1 expression, has improved our knowledge of iron metabolism and iron-related diseases. However, from both experimental data and clinical findings, "iron-related proteins" appear to also be involved in the metabolism of other metals, especially divalent cations. Reports have demonstrated that some metals may affect, directly or indirectly, the expression of proteins involved in iron metabolism. Throughout their lives, individuals are exposed to various metals during personal and/or occupational activities. Therefore, better knowledge of the connections between iron and other metals could improve our understanding of iron-related diseases, especially the variability in phenotypic expression, as well as a variety of diseases in which iron metabolism is secondarily affected. Controlling the metabolism of other metals could represent a promising innovative therapeutic approach.
[Show abstract][Hide abstract] ABSTRACT: Rare genetic iron overload diseases are an evolving field due to major advances in genetics and molecular biology. Genetic iron overload has long been confined to the classical type 1 hemochromatosis related to the HFE C282Y mutation. Breakthroughs in the understanding of iron metabolism biology and molecular mechanisms led to the discovery of new genes and subsequently, new types of hemochromatosis. To date, four types of hemochromatosis have been identified: HFE-related or type1 hemochromatosis, the most frequent form in Caucasians, and four rare types, named type 2 (A and B) hemochromatosis (juvenile hemochromatosis due to hemojuvelin and hepcidin mutation), type 3 hemochromatosis (related to transferrin receptor 2 mutation), and type 4 (A and B) hemochromatosis (ferroportin disease). The diagnosis relies on the comprehension of the involved physiological defect that can now be explored by biological and imaging tools, which allow non-invasive assessment of iron metabolism. A multidisciplinary approach is essential to support the physicians in the diagnosis and management of those rare diseases.
Gastroentérologie Clinique et Biologique 12/2013; · 0.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The development of alcoholic liver diseases depends on the ability of hepatocyte to proliferate and differentiate in the case of alcohol-induced injury. Our previous work showed an inhibitory effect of alcohol on hepatocyte proliferation. However, the effect of alcohol on hepatocyte differentiation has not yet been precisely characterized. In the present study, we evaluated the effect of alcohol on hepatocyte differentiation in relationship with changes of iron metabolism in HepaRG cells. This unique bipotent human cell line can differentiate into hepatocytes and biliary epithelial cells, paralleling liver development. Results showed that alcohol reduced cell viability, total protein level and enhanced hepatic enzymes leakage in differentiated HepaRG cells. Moreover, it caused cell enlargement, decreased number of hepatocyte and expression of C/EBPα as well as bile canaliculi F-actin. Alcohol increased expression of hepatic cell-specific markers and alcohol-metabolizing enzymes (ADH2, CYP2E1). This was associated with a lipid peroxidation and an iron excess expressed by an increase in total iron content, ferritin level, iron uptake as well as an overexpression of genes involved in iron transport and storage. Alcohol-induced hepatoxicity was amplified by exogenous iron via exceeding iron overload. Taken together, our data demonstrate that in differentiated hepatocytes, alcohol reduces proliferation while increasing expression of hepatic cell-specific markers. Moreover, iron overload could be one of the underlying mechanisms of effect of alcohol on the whole differentiation process of hepatocytes.
[Show abstract][Hide abstract] ABSTRACT: Ferroportin mediates iron export from cells and this function is modulated by serum hepcidin. Mutations in the ferroportin gene (SLC40A1) lead to autosomal dominant iron overload diseases related either to loss or to gain of function, and usually characterized by normal or low transferrin saturation versus elevated transferrin saturation respectively. However, for identical mutation, the phenotypic expression may vary from one patient to another. Using in vitro overexpression of wild-type or mutant ferroportin proteins, we characterized the functional impact of five recently identified ferroportin gene mutations regarding ferroportin localization, cell iron status, and hepcidin sensitivity. Our aim was to integrate functional results and biological findings in probands and relatives. We show that whereas the p.Arg371Gln (R371Q) mutation had no impact on studied parameters, the p.Trp158Leu (W158L), p.Arg88Gly (R88G), and p.Asn185Asp (N185D) mutations caused an iron export defect and were classified as loss-of-function mutations. The p.Gly204Ser (G204S) mutation induced a gain of ferroportin function. Functional studies are useful to determine whether or not a ferroportin gene mutation found in iron overloaded patient is deleterious and to characterize its biological impact, especially when family studies are not fully informative and/or additional confounding factors may affect bio-clinical expression. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: 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 showed that testosterone robustly represses hepcidin transcription by enhancing Egfr signaling in the liver and that selective 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: These data indicate that 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. They 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. (Hepatology 2013;).
[Show abstract][Hide abstract] ABSTRACT: Background: Defects in human hemochromatosis protein (HFE) cause iron overload due to reduced hepatic hepcidin secretion. Liver transplantation (LT) is a key treatment for potential complications from HFE- related hereditary hemochromatosis (HH). This study evaluated hepcidin secretion and iron burden after LT to elucidate HH pathophysiology. Methods: Patients (n=18) homozygous for the p.Cys282Tyr mutation in the HFE gene underwent LT between 1999 and 2008. Serum iron, serum hepcidin, and hepatic iron concentrations were determined before LT and at the end of follow-up (median 57 months). Mortality and causes of death were determined. Survival was compared to that of the overall patient population that received LT. Results: Before LT, serum hepcidin levels were low (0.54 ± 2.5 nmol/L; normal range: 4-30 nmol/L). After LT, 11 patients had iron evaluations; none received iron depletion therapy; all had normal transferrin saturation. The mean serum ferritin was 185 (±99) µg/L. Magnetic resonance imaging showed that iron overload was absent in 9 patients, mild in one patient with metabolic syndrome, and high (180 µmol/g) in one patient with hereditary spherocytosis unmasked after liver transplantation. At the end of follow-up, serum hepcidin was normal in 10 patients (11.12 ± 7.6 nmol/L; p<0.05) and low in one patient with iron deficiency anemia. Survival was 83% and 67% at one and 5 years, respectively. Survival was similar for patients with HH and patients that received LT for other causes. Conclusion: This study demonstrated that, in HH, LT normalized hepcidin secretion and prevented recurrence of hepatic iron overload. Survival was similar to that of patients that received LTs for other liver diseases. (HEPATOLOGY 2013.).
[Show abstract][Hide abstract] ABSTRACT: Las enfermedades por sobrecarga de hierro en los niños abarcan un amplio abanico de enfermedades genéticas y adquiridas. La identificación de las causas genéticas ha sido relativamente reciente, a raíz del descubrimiento del gen HFE. Se ha observado que, además de la hemocromatosis de tipo 1 (vinculada al gen HFE), que se manifiesta en la edad adulta, varias formas de sobrecarga de hierro que afectaban a pacientes jóvenes se debían a mutaciones de genes no relacionados con HFE. Se trata de enfermedades poco comunes pero que, a diferencia de la hemocromatosis vinculada al gen HFE, no afectan únicamente a pacientes caucásicos. El exceso de hierro está relacionado, como en la hemocromatosis de tipo 1, con una hipohepcidinemia que aumenta la absorción digestiva de hierro. Entre las causas adquiridas, predominan las sobrecargas de hierro que se desarrollan en el contexto de diversos trastornos hematológicos y están relacionadas no sólo con la transfusión de hierro, sino también con un exceso de absorción digestiva de éste, debido a hipohepcidinemia por diseritropoyesis. Desde el punto de vista diagnóstico, estas diversas enfermedades se han beneficiado en gran medida de la resonancia magnética (RM), para cuantificar de forma no invasiva la carga de hierro visceral, así como de los avances de la genética molecular, para identificar las mutaciones implicadas. Desde el punto de vista terapéutico, la depleción mediante sangrías es el tratamiento de primera línea de las sobrecargas genéticas. La quelación oral se ha convertido en el tratamiento de elección para las sobrecargas transfusionales. Con la condición de que se instauren de forma precoz, estos enfoques terapéuticos permiten no sólo transformar el pronóstico vital, sino mejorar sensiblemente la calidad de vida de estos jóvenes pacientes.
[Show abstract][Hide abstract] ABSTRACT: Natural polyamines such as putrescine (Put), spermidine (Spd), and spermine (Spm), which are present in the human diet in large amounts, associated with their active transporter, are assumed to play a role in non-heme iron uptake and iron bioavailability from nutrients. Enterocytes and hepatocytes play pivotal roles in the regulation of body iron homeostasis. In this study, we report the effects of natural polyamines on iron transport in the Caco-2 cell line. In enterocyte-like Caco-2 cells, polyamines did not significantly modulate the transepithelial iron flux across the cell monolayer cultured on permeable membranes. In contrast, Spd, Spm, and to a lesser extent, Put were shown to activate Caco-2 cell iron uptake and to induce an increase in the ferritin level. This iron co-transport in enterocytes, which involved an interaction between iron and polyamine then cell uptake of the polyamine-iron complexes by the polyamine transport system, was more pronounced in proliferating than in differentiated Caco-2 cells. Moreover, it was observed at physiological concentrations of both polyamines and iron. It could thus play a role in the rapid renewal of enterocytes. These data suggest the involvement of polyamines as components of the pool of transferrin-independent iron-chelating vectors. Further investigations are needed to demonstrate their biological relevance in physiological situations.
Molecular and Cellular Biochemistry 03/2013; · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An occurrence and a magnitude of alcoholic liver diseases depend on the balance between ethanol-induced injury and liver regeneration. Like ethanol, polyamines including putrescine, spermidine, and spermine modulate cell proliferation. Thus, the purpose of this study was to evaluate the relationship between effect of ethanol on hepatocyte (HC) proliferation and polyamine metabolism using the HepaRG cell model. Results showed that ethanol effect in proliferating HepaRG cells was associated with a decrease in intracellular polyamine levels and ornithine decarboxylase (ODC) activity. Ethanol also induced disorders in expression of genes coding for polyamine-metabolizing enzymes. The α-difluoromethyl ornithine, an irreversible inhibitor of ODC, amplified ethanol toxicity on cell viability, protein level, and DNA synthesis through accentuation of polyamine depletion in proliferating HepaRG cells. Conversely, putrescine reversed ethanol effect on cell proliferation parameters. In conclusion, this study suggested that ethanol effect on HC proliferation was closely related to polyamine metabolism and that manipulation of this metabolism by putrescine could protect against the anti-proliferative activity of ethanol.
[Show abstract][Hide abstract] ABSTRACT: Iron chelation in tumoral cells has been reported as potentially useful during antitumoral treatment. Our aim was to develop new polyaminoquinoline iron chelators targeting tumoral cells. For this purpose, we designed, synthesized, and evaluated the biological activity of a new generation of iron chelators, which we named Quilamines, based on an 8-hydroxyquinoline (8-HQ) scaffold linked to linear polyamine vectors. These were designed to target tumor cells expressing an overactive polyamine transport system (PTS). A set of Quilamines bearing variable polyamine chains was designed and assessed for their ability to interact with iron. Quilamines were also screened for their cytostatic/cytotoxic effects and their selective uptake by the PTS in the CHO cell line. Our results show that both the 8-HQ moiety and the polyamine part participate in the iron coordination. HQ1-44, the most promising Quilamine identified, presents a homospermidine moiety and was shown to be highly taken up by the PTS and to display an efficient antiproliferative activity that occurred in the micromolar range. In addition, cytotoxicity was only observed at concentrations higher than 100 μM. We also demonstrated the high complexation capacity of HQ1-44 with iron while much weaker complexes were formed with other cations, indicative of a high selectivity. We applied the density functional theory to study the binding energy and the electronic structure of prototypical iron(III)-Quilamine complexes. On the basis of these calculations, Quilamine HQ1-44 is a strong tridentate ligand for iron(III) especially in the form of a 1:2 complex.
[Show abstract][Hide abstract] ABSTRACT: Iron is required for the biological activities of a large number of proteins and is therefore needed for cell life. However, iron in excess is toxic, mainly due to its ability to promote the appearance of oxygen reactive species. Therefore, iron metabolism must be strictly controlled. This control takes, firstly, place at the systemic level through the hepcidin-ferroportin couple. Hepcidin, a peptide secreted by hepatocytes, interacts with ferroportin which allows iron egress from enterocytes and macrophages, the main providers of iron for plasma. Therefore, hepcidin controls iron leakage and plasma iron bioavailability. Abnormal levels of hepcidin are involved in the development either or iron overload diseases or iron deficiency. Iron metabolism control takes place, secondly, within the cells, thanks to the iron regulatoty protein/iron responsive element system which coordinates levels of transferrin iron uptake and iron storage capacity, in order to avoid deleterious situations for cells. Understanding the mechanisms which control iron metabolism paves the road for the development of new diagnostic and therapeutic tools. For the later, it will be necessary to integrate benefits that could be associated with abnormalities of iron metabolism occurring during inflammation.
Cahiers de Nutrition et de Diététique 06/2012; 47(3):117–124.
[Show abstract][Hide abstract] ABSTRACT: Iron is involved in many biological functions and is therefore required for cell life. However, when present in excess, it is toxic. Maintenance of adequate levels of iron as well as its proper distribution in the body and cells are possible through systemic and cellular mechanisms. Systemic control of iron metabolism involves hepcidin, a peptide secreted by hepatocytes, and ferroportin, the iron exporter from macrophages and enterocytes toward plasma. Hepcidin interacts with ferroportin and causes its degradation, thus controlling the level of plasma iron. Abnormal levels of hepcidin are involved in the onset of iron overload or deficiency. Understanding the mechanisms controlling hepcidin levels is therefore a major issue. Control of cellular iron involves the iron regulatory protein/iron responsive element system that regulates transferrin-iron uptake by cells as well as the iron storage capacity, thus avoiding cell damage. New knowledge on iron metabolism permits a better understanding of the mechanisms involved in iron metabolism disorders. From this knowledge, new diagnostic and therapeutic strategies will improve the patients management.
Revue Francophone des Laboratoires 05/2012; 2012(442):31–37.