Publications by authors named "Zoubida Karim"

51 Publications

Control of Systemic Iron Homeostasis by the 3' Iron-Responsive Element of Divalent Metal Transporter 1 in Mice.

Hemasphere 2020 Oct 23;4(5):e459. Epub 2020 Sep 23.

German Cancer Research Center (DKFZ), Division of Virus-Associated Carcinogenesis (F170), Heidelberg, Germany.

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http://dx.doi.org/10.1097/HS9.0000000000000459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7523796PMC
October 2020

Iron chelation rescues hemolytic anemia and skin photosensitivity in congenital erythropoietic porphyria.

Blood 2020 11;136(21):2457-2468

University Bordeaux, INSERM, Biotherapy of Genetic Diseases, Inflammation and Cancer (BMGIC), U1035, CHU Bordeaux, Bordeaux, France.

Congenital erythropoietic porphyria (CEP) is an inborn error of heme synthesis resulting from uroporphyrinogen III synthase (UROS) deficiency and the accumulation of nonphysiological porphyrin isomer I metabolites. Clinical features are heterogeneous among patients with CEP but usually combine skin photosensitivity and chronic hemolytic anemia, the severity of which is related to porphyrin overload. Therapeutic options include symptomatic strategies only and are unsatisfactory. One promising approach to treating CEP is to reduce the erythroid production of porphyrins through substrate reduction therapy by inhibiting 5-aminolevulinate synthase 2 (ALAS2), the first and rate-limiting enzyme in the heme biosynthetic pathway. We efficiently reduced porphyrin accumulation after RNA interference-mediated downregulation of ALAS2 in human erythroid cellular models of CEP disease. Taking advantage of the physiological iron-dependent posttranscriptional regulation of ALAS2, we evaluated whether iron chelation with deferiprone could decrease ALAS2 expression and subsequent porphyrin production in vitro and in vivo in a CEP murine model. Treatment with deferiprone of UROS-deficient erythroid cell lines and peripheral blood CD34+-derived erythroid cultures from a patient with CEP inhibited iron-dependent protein ALAS2 and iron-responsive element-binding protein 2 expression and reduced porphyrin production. Furthermore, porphyrin accumulation progressively decreased in red blood cells and urine, and skin photosensitivity in CEP mice treated with deferiprone (1 or 3 mg/mL in drinking water) for 26 weeks was reversed. Hemolysis and iron overload improved upon iron chelation with full correction of anemia in CEP mice treated at the highest dose of deferiprone. Our findings highlight, in both mouse and human models, the therapeutic potential of iron restriction to modulate the phenotype in CEP.
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http://dx.doi.org/10.1182/blood.2020006037DOI Listing
November 2020

A hepcidin-based approach for iron therapy in hemodialysis patients: A pilot study.

Hemodial Int 2020 04 11;24(2):188-194. Epub 2020 Feb 11.

Institut National de Santé en Recherche Médicale (INSERM) U1149, Centre de recherche sur l'inflammation, Paris, France.

Introduction: Hepcidin is a key factor that regulates iron homeostasis. In hemodialysis patients (HD), a high hepcidin level may decrease intestinal iron absorption and reduce the efficacy of Oral iron vs Intravenous iron therapy. Whether the hepcidin level in HD could guide oral iron therapy is unclear.

Methods: We report a monocentric study on nine "erythropoietin (EPO)-free" patients (without recombinant human EPO [rHU-EPO] for at least 6 months) and normal hepcidin level (<20 ng mL) during the study. After 15 days of washout, oral iron (ferrous sulfate 80 mg/day) was introduced. The primary end point was the hemoglobin response and iron store at 3 months.

Findings: Nine patients (8 men, 1 woman) with a median age of 62 years (range 42-79) were included. After 1 week of treatment, the median transferrin saturation index increased from 15% (range 6-61) to 34% (range 13-42), P = 0.62, reflecting intestinal absorption. The median ferritin level remained stable 80 μg/L (35-293) vs 82 μg/L (range 37-496) between M0 and M3, P = 0.43. During the 3-month study, median hemoglobin level increased from 11.5 d/dL (range10.4-13.7) to 12.8 g/dL (range 11.1-15.2), P = 0.01. No major side effects were observed. Quality of life assessed by the SF-36 criteria was similar during the 3-month study.

Discussion: Oral iron therapy is effective and safe in EPO-free patients with normal hepcidin levels. These findings suggest that serum hepcidin may be a marker for defining iron therapy strategies in HD patients. HD patients treated with rHU-EPO and with normal hepcidin levels could benefit from oral iron treatment.
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http://dx.doi.org/10.1111/hdi.12823DOI Listing
April 2020

Genetic background influences hepcidin response to iron imbalance in a mouse model of hemolytic anemia (Congenital erythropoietic porphyria).

Biochem Biophys Res Commun 2019 12 7;520(2):297-303. Epub 2019 Oct 7.

Laboratory of excellence, GR-Ex, Paris, France; INSERM U1035, Biothérapie des Maladies Génétiques, Inflammatoires et Cancers, France; Université de Bordeaux, 33000, Bordeaux, France. Electronic address:

Clinical severity is heterogeneous among patients suffering from congenital erythropoietic porphyria (CEP) suggesting a modulation of the disease (UROS deficiency) by environmental factors and modifier genes. A KI model of CEP due to a missense mutation of UROS gene present in human has been developed on 3 congenic mouse strains (BALB/c, C57BL/6, and 129/Sv) in order to study the impact of genetic background on disease severity. To detect putative modifiers of disease expression in congenic mice, hematologic data, iron parameters, porphyrin content and tissue samples were collected. Regenerative hemolytic anemia, a consequence of porphyrin excess in RBCs, had various expressions: 129/Sv mice were more hemolytic, BALB/c had more regenerative response to anemia, C57BL/6 were less affected. Iron status and hemolysis level were directly related: C57BL/6 and BALB/c had moderate hemolysis and active erythropoiesis able to reduce iron overload in the liver, while, 129/Sv showed an imbalance between iron release due to hemolysis and erythroid use. The negative control of hepcidin on the ferroportin iron exporter appeared strain specific in the CEP mice models tested. Full repression of hepcidin was observed in BALB/c and 129/Sv mice, favoring parenchymal iron overload in the liver. Unchanged hepcidin levels in C57BL/6 resulted in retention of iron predominantly in reticuloendothelial tissues. These findings open the field for potential therapeutic applications in the human disease, of hepcidin agonists and iron depletion in chronic hemolytic anemia.
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http://dx.doi.org/10.1016/j.bbrc.2019.09.141DOI Listing
December 2019

Extrahepatic hepcidin production: The intriguing outcomes of recent years.

World J Clin Cases 2019 Aug;7(15):1926-1936

Université Paris Diderot, Bichat site, Paris 75018, France.

Hepcidin is the hyposideremic hormone regulating iron metabolism. It is a defensin-like disulfide-bonded peptide with antimicrobial activity. The main site of hepcidin production is the liver where its synthesis is modulated by iron, inflammation and erythropoietic signaling. However, hepcidin locally produced in several peripheral organs seems to be an important actor for the maintenance of iron homeostasis in these organs. This review highlights the presence of peripheral hepcidin and its potential functions. Understanding the role of extrahepatic hepcidin could be of great physiological and therapeutic importance for several specific pathologies.
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http://dx.doi.org/10.12998/wjcc.v7.i15.1926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6695539PMC
August 2019

A variant erythroferrone disrupts iron homeostasis in -mutated myelodysplastic syndrome.

Sci Transl Med 2019 07;11(500)

Université de Paris, Paris 75006, France.

Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the splicing factor gene. Patients with MDS with mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative transcript in patients with MDS with the mutation. Induction of this transcript in primary -mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an gene mutation than in patients with wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with -mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant transcript that was restricted to -mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.
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http://dx.doi.org/10.1126/scitranslmed.aav5467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005358PMC
July 2019

Regulation and tissue-specific expression of δ-aminolevulinic acid synthases in non-syndromic sideroblastic anemias and porphyrias.

Mol Genet Metab 2019 11 23;128(3):190-197. Epub 2019 Jan 23.

INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; AP-HP, HUPNVS, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes, France. Electronic address:

Recently, new genes and molecular mechanisms have been identified in patients with porphyrias and sideroblastic anemias (SA). They all modulate either directly or indirectly the δ-aminolevulinic acid synthase (ALAS) activity. ALAS, is encoded by two genes: the erythroid-specific (ALAS2), and the ubiquitously expressed (ALAS1). In the liver, ALAS1 controls the rate-limiting step in the production of heme and hemoproteins that are rapidly turned over in response to metabolic needs. Several heme regulatory targets have been identified as regulators of ALAS1 activity: 1) transcriptional repression via a heme-responsive element, 2) post-transcriptional destabilization of ALAS1 mRNA, 3) post-translational inhibition via a heme regulatory motif, 4) direct inhibition of the activity of the enzyme and 5) breakdown of ALAS1 protein via heme-mediated induction of the protease Lon peptidase 1. In erythroid cells, ALAS2 is a gatekeeper of production of very large amounts of heme necessary for hemoglobin synthesis. The rate of ALAS2 synthesis is transiently increased during the period of active heme synthesis. Its gene expression is determined by trans-activation of nuclear factor GATA1, CACC box and NF-E2-binding sites in the promoter areas. ALAS2 mRNA translation is also regulated by the iron-responsive element (IRE)/iron regulatory proteins (IRP) binding system. In patients, ALAS enzyme activity is affected in most of the mutations causing non-syndromic SA and in several porphyrias. Decreased ALAS2 activity results either directly from loss-of-function ALAS2 mutations as seen in X-linked sideroblastic anemia (XLSA) or from defect in the availability of one of its two mitochondrial substrates: glycine in SLC25A38 mutations and succinyl CoA in GLRX5 mutations. Moreover, ALAS2 gain of function mutations is responsible for X-linked protoporphyria and increased ALAS1 activity lead to acute attacks of hepatic porphyrias. A missense dominant mutation in the Walker A motif of the ATPase binding site in the gene coding for the mitochondrial protein unfoldase CLPX also contributes to increasing ALAS and subsequently protoporphyrinemia. Altogether, these recent data on human ALAS have informed our understanding of porphyrias and sideroblastic anemias pathogeneses and may contribute to new therapeutic strategies.
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http://dx.doi.org/10.1016/j.ymgme.2019.01.015DOI Listing
November 2019

Erythroid-Progenitor-Targeted Gene Therapy Using Bifunctional TFR1 Ligand-Peptides in Human Erythropoietic Protoporphyria.

Am J Hum Genet 2019 02 31;104(2):341-347. Epub 2019 Jan 31.

Centre de Recherches sur l'Inflammation, Institut National de la Santé et de la Recherche Médicale U1149, 75018 Paris, France; Université Paris Diderot, 75018 Paris, France; Centre Français des Porphyries, Hôpital Louis Mourier, Assistance Publique-Hôpitaux de Paris, 178 rue des Renouillers, 92701 Colombes, France; Laboratory of Excellence GR-Ex, 75015 Paris, France. Electronic address:

Erythropoietic protoporphyria (EPP) is a hereditary disease characterized by a deficiency in ferrochelatase (FECH) activity. FECH activity is responsible for the accumulation of protoporphyrin IX (PPIX). Without etiopathogenic treatment, EPP manifests as severe photosensitivity. 95% of affected individuals present a hypomorphic FECH allele trans to a loss-of-function (LOF) FECH mutation, resulting in a reduction in FECH activity in erythroblasts below a critical threshold. The hypomorphic allele promotes the use of a cryptic acceptor splice site, generating an aberrant FECH mRNA, which is responsible for the reduced level of wild-type FECH mRNA and, ultimately, FECH activity. We have previously identified an antisense oligonucleotide (AON), AON-V1 (V1), that redirects splicing to the physiological acceptor site and reduces the accumulation of PPIX. Here, we developed a specific strategy that uses transferrin receptor 1 (TRF1) as a Trojan horse to deliver V1 to erythroid progenitors. We designed a bifunctional peptide (P-9R) including a TFR1-targeting peptide coupled to a nine-arginine cell-penetrating peptide (CPP) that facilitates the release of the AON from TFR1 in endosomal vesicles. We demonstrated that the P-9R/V1 nanocomplex promotes the efficient and prolonged redirection of splicing towards the physiological splice site and subsequent normalization of WT FECH mRNA and protein levels. Finally, the P-9R/V1 nanocomplex increases WT FECH mRNA production and significantly decreases PPIX accumulation in primary cultures of differentiating erythroid progenitors from an overt EPP-affected individual. P-9R is a method designed to target erythroid progenitors and represents a potentially powerful tool for the in vivo delivery of therapeutic DNA in many erythroid disorders.
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http://dx.doi.org/10.1016/j.ajhg.2018.12.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369449PMC
February 2019

Regulation of globin-heme balance in Diamond-Blackfan anemia by HSP70/GATA1.

Blood 2019 03 30;133(12):1358-1370. Epub 2019 Jan 30.

INSERM U1149/ERL 8252, Inflammation Research Center, Paris, France.

Diamond-Blackfan anemia (DBA) is a congenital erythroblastopenia that is characterized by a blockade in erythroid differentiation related to impaired ribosome biogenesis. DBA phenotype and genotype are highly heterogeneous. We have previously identified 2 in vitro erythroid cell growth phenotypes for primary CD34 cells from DBA patients and following short hairpin RNA knockdown of RPS19, RPL5, and RPL11 expression in normal human CD34 cells. The haploinsufficient RPS19 in vitro phenotype is less severe than that of 2 other ribosomal protein (RP) mutant genes. We further documented that proteasomal degradation of HSP70, the chaperone of GATA1, is a major contributor to the defect in erythroid proliferation, delayed erythroid differentiation, increased apoptosis, and decreased globin expression, which are all features of the RPL5 or RPL11 DBA phenotype. In the present study, we explored the hypothesis that an imbalance between globin and heme synthesis may be involved in pure red cell aplasia of DBA. We identified disequilibrium between the globin chain and the heme synthesis in erythroid cells of DBA patients. This imbalance led to accumulation of excess free heme and increased reactive oxygen species production that was more pronounced in cells of the RPL5 or RPL11 phenotype. Strikingly, rescue experiments with wild-type HSP70 restored GATA1 expression levels, increased globin synthesis thereby reducing free heme excess and resulting in decreased apoptosis of DBA erythroid cells. These results demonstrate the involvement of heme in DBA pathophysiology and a major role of HSP70 in the control of balanced heme/globin synthesis.
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http://dx.doi.org/10.1182/blood-2018-09-875674DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6428670PMC
March 2019

The Relevancy of Data Regarding the Metabolism of Iron to Our Understanding of Deregulated Mechanisms in ALS; Hypotheses and Pitfalls.

Front Neurosci 2018 15;12:1031. Epub 2019 Jan 15.

Laboratoire de Biochimie, CHRU de Tours, Tours, France.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the loss of motor neurons. Its etiology remains unknown, but several pathophysiological mechanisms are beginning to explain motor neuronal death, as well as oxidative stress. Iron accumulation has been observed in both sporadic and familial forms of ALS, including mouse models. Therefore, the dysregulation of iron metabolism could play a role in the pathological oxidative stress in ALS. Several studies have been undertaken to describe iron-related metabolic markers, in most cases focusing on metabolites in the bloodstream due to few available data in the central nervous system. Reports of accumulation of iron, high serum ferritin, and low serum transferrin levels in ALS patients have encouraged researchers to consider dysregulated iron metabolism as an integral part of ALS pathophysiology. However, it appears complicated to suggest a general mechanism due to the diversity of models and iron markers studied, including the lack of consensus among all of the studies. Regarding clinical study reports, most of them do not take into account confusion biases such as inflammation, renal dysfunction, and nutritional status. Furthermore, the iron regulatory pathways, particularly involving hepcidin, have not been thoroughly explored yet within the pathogenesis of iron overload in ALS. In this sense, it is also essential to explore the relation between iron overload and other ALS-related events, such as neuro-inflammation, protein aggregation, and iron-driven cell death, termed ferroptosis. In this review, we point out limits of the designs of certain studies that may prevent the understanding of the role of iron in ALS and discuss the relevance of the published data regarding the pathogenic impact of iron metabolism deregulation in this disease and the therapeutics targeting this pathway.
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http://dx.doi.org/10.3389/fnins.2018.01031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6341213PMC
January 2019

GLRX5 mutations impair heme biosynthetic enzymes ALA synthase 2 and ferrochelatase in Human congenital sideroblastic anemia.

Mol Genet Metab 2019 11 7;128(3):342-351. Epub 2019 Jan 7.

INSERM U1149, Centre de Recherche sur l'inflammation (CRI), Paris, France; Université Paris Diderot, site Bichat, Sorbonne Paris cité, DHU UNITY, Paris, France; Laboratory of excellence GR-Ex, Paris, France. Electronic address:

Non-syndromic microcytic congenital sideroblastic anemia (cSA) is predominantly caused by defective genes encoding for either ALAS2, the first enzyme of heme biosynthesis pathway or SLC25A38, the mitochondrial importer of glycine, an ALAS2 substrate. Herein we explored a new case of cSA with two mutations in GLRX5, a gene for which only two patients have been reported so far. The patient was a young female with biallelic compound heterozygous mutations in GLRX5 (p.Cys67Tyr and p.Met128Lys). Three-D structure analysis confirmed the involvement of Cys67 in the coordination of the [2Fe2S] cluster and suggested a potential role of Met128 in partner interactions. The protein-level of ferrochelatase, the terminal-enzyme of heme process, was increased both in patient-derived lymphoblastoid and CD34+ cells, however, its activity was drastically decreased. The activity of ALAS2 was found altered and possibly related to a defect in the biogenesis of its co-substrate, the succinyl-CoA. Thus, the patient exhibits both a very low ferrochelatase activity without any accumulation of porphyrins precursors in contrast to what is reported in erythropoietic protoporphyria with solely impaired ferrochelatase activity. A significant oxidative stress was evidenced by decreased reduced glutathione and aconitase activity, and increased MnSOD protein expression. This oxidative stress depleted and damaged mtDNA, decreased complex I and IV activities and depleted ATP content. Collectively, our study demonstrates the key role of GLRX5 in modulating ALAS2 and ferrochelatase activities and in maintaining mitochondrial function.
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http://dx.doi.org/10.1016/j.ymgme.2018.12.012DOI Listing
November 2019

Hepatocellular carcinoma in acute hepatic porphyrias: A Damocles Sword.

Mol Genet Metab 2019 11 9;128(3):236-241. Epub 2018 Oct 9.

UMRs 1149, Centre de Recherche sur l'Inflammation, Institut National de la Santé et de la Recherche Médicale, F-75018 Paris, France; Assistance Publique-Hôpitaux de Paris, HUPNVS Centre Français des Porphyries, Hôpital Louis Mourier, 178 Rue des Renouillers, F-92701 Colombes, France; Laboratory of Excellence Gr-Ex, France; Université Paris Diderot, UFR de Médecine Xavier Bichat, F-75018 Paris, France.

Porphyrias are inherited diseases with low penetrance affecting the heme biosynthesis pathway. Acute intermittent porphyria (AIP), variegate porphyria (VP) and hereditary coproporphyria (HCP) together constitute the acute hepatic porphyrias (AHP). These diseases have been identified as risk factors for primary liver cancers (PLC), mainly hepatocellular carcinoma (HCC: range 87-100%) but also cholangiocarcinoma, alone or combination with HCC. In AHP, HCC annual incidence rates range from 0.16 to 0.35% according to the populations studied. Annual incidence rates are higher in Swedish and Norwegian patients, due to a founder effect. It increases above age 50. The pathophysiology could include both direct toxic effects of heme precursors, particularly δ-aminolevulinic acid (ALA), compound heterozygosity for genes implied in heme biosynthesis pathway or the loss of oxidative stress homeostasis due to a relative lack of heme. The high HCC incidence justifies radiological surveillance in AHP patients above age 50. Efforts are made to find new biological non-invasive markers. In this respect, we describe here the first report of PIVKA-II clinical utility in the follow-up of an AIP patient that develop an HCC. In this manuscript we reviewed the epidemiology, the physiopathology, and the screening strategy of HCC in AHP.
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http://dx.doi.org/10.1016/j.ymgme.2018.10.001DOI Listing
November 2019

Dyserythropoiesis evaluated by the RED score and hepcidin:ferritin ratio predicts response to erythropoietin in lower-risk myelodysplastic syndromes.

Haematologica 2019 03 4;104(3):497-504. Epub 2018 Oct 4.

Department of Hematology, CHU Grenoble-Alpes, Grenoble.

Erythropoiesis-stimulating agents are generally the first line of treatment of anemia in patients with lower-risk myelodysplastic syndrome. We prospectively investigated the predictive value of somatic mutations, and biomarkers of ineffective erythropoiesis including the flow cytometry RED score, serum growth-differentiation factor-15, and hepcidin levels. Inclusion criteria were no prior treatment with erythropoiesis-stimulating agents, low- or intermediate-1-risk myelodysplastic syndrome according to the International Prognostic Scoring System, and a hemoglobin level <10 g/dL. Patients could be red blood cell transfusion-dependent or not and were given epoetin zeta 40 000 IU/week. Serum erythropoietin level, iron parameters, hepcidin, flow cytometry Ogata and RED scores, and growth-differentiation factor-15 levels were determined at baseline, and molecular analysis by next-generation sequencing was also conducted. Erythroid response (defined according to the International Working Group 2006 criteria) was assessed at week 12. Seventy patients, with a median age of 78 years, were included in the study. There were 22 patients with refractory cytopenia with multilineage dysplasia, 19 with refractory cytopenia with unilineage dysplasia, 14 with refractory anemia with ring sideroblasts, four with refractory anemia with excess blasts-1, six with chronic myelomonocytic leukemia, two with del5q-and three with unclassifiable myelodysplastic syndrome. According to the revised International Prognostic Scoring System, 13 had very low risk, 47 had low risk, nine intermediate risk and one had high-risk disease. Twenty patients were transfusion dependent. Forty-eight percent had an erythroid response and the median duration of the response was 26 months. At baseline, non-responders had significantly higher RED scores and lower hepcidin:ferritin ratios. In multivariate analysis, only a RED score >4 (=0.05) and a hepcidin:ferritin ratio <9 (=0.02) were statistically significantly associated with worse erythroid response. The median response duration was shorter in patients with growth-differentiation factor-15 >2000 pg/mL and a hepcidin:ferritin ratio <9 (=0.0008 and =0.01, respectively). In multivariate analysis, both variables were associated with shorter response duration. Erythroid response to epoetin zeta was similar to that obtained with other erythropoiesis-stimulating agents and was correlated with higher baseline hepcidin:ferritin ratio and lower RED score. .
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http://dx.doi.org/10.3324/haematol.2018.203158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395339PMC
March 2019

Functional erythropoietin-hepcidin axis in recombinant human erythropoietin independent haemodialysis patients.

Nephrology (Carlton) 2019 Jul 25;24(7):751-757. Epub 2019 Apr 25.

Institut National de Santé en Recherche Médicale (INSERM) U1149, centre de recherche sur l'inflammation, Centre de recherche sur l'inflammation, Paris, France.

Aim: Relatively few haemodialysis (HD) patients remain independent of recombinant human erythropoietin ('rHU-EPO free patients'). We investigated the role of EPO and hepcidin, two key hormones involved in anaemia.

Methods: We report a monocentric case-control series. Iron status, EPO and hepcidin levels were analysed in 15 Adult HD (Age > 18 years) with a stable haemoglobin (Hb) level that have not received rHU-EPO for at least 6 months (=rHU-EPO free patients); and in 60 controls with a stable rHU-EPO dose and Hb level.

Results: The rHU-EPO free patients had a higher Hb level compared to controls (12.1 ± 0.99 g/dL vs 11.1 ± 0.73, P = 0.0014), and a lower ferritin level (183 ± 102 vs 312 ± 166 ng/mL, P = 0.001). Hepcidin levels were lower in the rHU-EPO free patients (12.53 ± 10.46 ng/mL) compared to the controls (37.95 ± 34.33 ng/mL), P = 0.0033. Hepcidin levels correlated significantly with ferritin levels; but neither with transferrin saturation, C-reactive protein nor EPO levels. Unsupervised analysis revealed that rHU-EPO free patients had a specific clinical/biological profile (presence of renal cyst, longer dialysis vintage, lower ferritin, and EPO and hepcidin levels compared to the control group). Finally, we showed that a lower ferritin level might be a surrogate marker of a lower hepcidin status in this population.

Conclusion: Recombinant human erythropoietin free patients seem to restore the EPO-hepcidin axis that is critical for erythropoiesis. A specific combination of clinical and biological parameters may help to detect future rHU-EPO free patients.
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http://dx.doi.org/10.1111/nep.13485DOI Listing
July 2019

High urinary ferritin reflects myoglobin iron evacuation in DMD patients.

Neuromuscul Disord 2018 07 20;28(7):564-571. Epub 2018 Mar 20.

Généthon, Evry, France. Electronic address:

Duchenne muscular dystrophy (DMD) is an X-linked disease caused by mutations in the dystrophin gene leading to the absence of the normal dystrophin protein. The efforts of many laboratories brought new treatments of DMD to the reality, but ongoing and forthcoming clinical trials suffer from absence of valuable biomarkers permitting to follow the outcome of the treatment day by day and to adjust the treatment if needed. In the present study the levels of 128 urinary proteins including growth factors, cytokines and chemokines were compared in urine of DMD patients and age related control subjects by antibody array approach. Surprisingly, statistically significant difference was observed only for urinary ferritin whose level was 50 times higher in young DMD patients. To explain the observed high urinary ferritin content we analysed the levels of iron, iron containing proteins and proteins involved in regulation of iron metabolism in serum and urine of DMD patients and their age-matched healthy controls. Obtained data strongly suggest that elevated level of urinary ferritin is functionally linked to the renal management of myoglobin iron derived from leaky muscles of DMD patients. This first observation of the high level of ferritin in urine of DMD patients permits to consider this protein as a new urinary biomarker in muscular dystrophies and sheds light on the mechanisms of iron metabolism and kidney functioning in DMD.
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http://dx.doi.org/10.1016/j.nmd.2018.03.008DOI Listing
July 2018

Porphyria and kidney diseases.

Clin Kidney J 2018 Apr 10;11(2):191-197. Epub 2018 Jan 10.

Centre Francais des Porphyries, Hôpital Louis Mourier, Assistance Publique-Hôpitaux de Paris, Colombes, France.

The kidneys, after the bone marrow and liver, are third in terms of the amounts of haem synthesized daily. Haem is incorporated into haemoproteins that are critical to renal physiology. In turn, disturbances in haem metabolism interfere with renal physiology and are tightly interrelated with kidney diseases. Acute intermittent porphyria causes kidney injury, whereas medical situations associated with end-stage renal disease, such as porphyrin accumulation, iron overload and hepatitis C, participate in the inhibition of uroporphyrinogen decarboxylase and predispose the individual to porphyria cutanea tarda. Even if some of these interactions have been known for a long time, the clinical situations associated with these interrelations have strikingly evolved over time with the advent of new therapeutic strategies for dialysis therapy and a better understanding of the pathophysiological mechanisms of porphyria-associated kidney disease. Physicians should be aware of these interactions. The aim of this review is to summarize the complex interactions between kidney physiology and pathology in the settings of porphyria and to emphasize their often-underestimated importance.
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http://dx.doi.org/10.1093/ckj/sfx146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5888040PMC
April 2018

Predominant role of microglia in brain iron retention in Sanfilippo syndrome, a pediatric neurodegenerative disease.

Glia 2018 08 6;66(8):1709-1723. Epub 2018 Apr 6.

Unité INSERM U1088, CURS-Université de Picardie Jules Verne, Amiens, F-80054, France.

Neuroinflammation and iron accumulation are hallmarks of a variety of adult neurodegenerative diseases. In Sanfilippo syndrome (mucopolysaccharidosis type III, MPSIII, a pediatric neurodegenerative disease that shares some features with adult neurodegenerative diseases), the progressive accumulation of heparan sulfate oligosaccharides (HSOs) induces microglia and astrocytes to produce pro-inflammatory cytokines leading to severe neuroinflammation. The objectives of the present study were (1) to measure the local iron concentration and to assess iron metabolism in the brain of a MPSIIIB murine model and (2) to identify the brain cells involved in this accumulation. We found that iron accumulation in MPSIIIB mice primarily affected the cerebral cortex where hepcidin levels were higher than in wild-type mice, and increased with aging. This increase was correlated with low expression of ferroportin 1 (FPN1), and thus brain iron retention. Moreover, we showed in vitro that HSOs are directly responsible for the production of hepcidin and the relative decrease in FPN1 expression when added to cultures of microglia and, to a lesser extent, to cultures of astrocytes. In contrast, no significant differences were observed in neurons. Hepcidin induction results from activation of the TLR4 pathway and STAT3 signaling, and leads to iron retention within microglia. Our results show that microglia have a key role in cerebral hepcidin overexpression and thus in the brain iron accumulation observed in the MPSIIIB model.
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http://dx.doi.org/10.1002/glia.23335DOI Listing
August 2018

From a dominant to an oligogenic model of inheritance with environmental modifiers in acute intermittent porphyria.

Hum Mol Genet 2018 04;27(7):1164-1173

UMRs 1149, Centre de Recherche sur l'Inflammation, Institut National de la Santé et de la Recherche Médicale, F-75018 Paris, France.

Acute intermittent porphyria (AIP) is a disease affecting the heme biosynthesis pathway caused by mutations of the hydroxymethylbilane synthase (HMBS) gene. AIP is thought to display autosomal dominant inheritance with incomplete penetrance. We evaluated the prevalence, penetrance and heritability of AIP, in families with the disease from the French reference center for porphyria (CFP) (602 overt patients; 1968 relatives) and the general population, using Exome Variant Server (EVS; 12 990 alleles) data. The pathogenicity of the 42 missense variants identified was assessed in silico, and in vitro, by measuring residual HMBS activity of the recombinant protein. The minimal estimated prevalence of AIP in the general population was 1/1299. Thus, 50 000 subjects would be expected to carry the AIP genetic trait in France. Penetrance was estimated at 22.9% in families with AIP, but at only 0.5-1% in the general population. Intrafamily correlation studies showed correlations to be strong overall and modulated by kinship and the area in which the person was living, demonstrating strong influences of genetic and environmental modifiers on inheritance. Null alleles were associated with a more severe phenotype and a higher penetrance than for other mutant alleles. In conclusion, the striking difference in the penetrance of HMBS mutations between the general population and the French AIP families suggests that AIP inheritance does not follow the classical autosomal dominant model, instead of being modulated by strong environmental and genetic factors independent from HMBS. An oligogenic inheritance model with environmental modifiers might better explain AIP penetrance and heritability.
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http://dx.doi.org/10.1093/hmg/ddy030DOI Listing
April 2018

Involvement of hepcidin in iron metabolism dysregulation in Gaucher disease.

Haematologica 2018 04 5;103(4):587-596. Epub 2018 Jan 5.

University Sorbonne Paris Cité, Paris Diderot University, Inserm U1149 / ERL 8252, Inflammation Research Center (CRI), Laboratory of Excellence GR-Ex, Paris, France

Gaucher disease (GD) is an inherited deficiency of glucocerebrosidase leading to accumulation of glucosylceramide in tissues such as the spleen, liver, and bone marrow. The resulting lipid-laden macrophages lead to the appearance of "Gaucher cells". Anemia associated with an unexplained hyperferritinemia is a frequent finding in GD, but whether this pathogenesis is related to an iron metabolism disorder has remained unclear. To investigate this issue, we explored the iron status of a large cohort of 90 type I GD patients, including 66 patients treated with enzyme replacement therapy. Ten of the patients treated with enzyme replacement were followed up before and during treatment. Serum levels of hepcidin, the iron regulatory peptide, remained within the physiological range, while the transferrin saturation was slightly decreased in children. Inflammation-independent hyperferritinemia was found in 65% of the patients, and Perl's staining of the spleen and marrow smear revealed iron accumulation in Gaucher cells. Treated patients exhibited reduced hyperferritinemia, increased transferrin saturation and transiently increased systemic hepcidin. In addition, the hepcidin and ferritin correlation was markedly improved, and, in most patients, the hemoglobin level was normalized. To further explore eventual iron sequestration in macrophages, we produce a Gaucher cells model by treating the J774 macrophage cell line with a glucocerebrosidase inhibitor and showed induced local hepcidin and membrane retrieval of the iron exporter, ferroportin. These data reveal the involvement of Gaucher cells in abnormal iron sequestration, which may explain the mechanism of hyperferritinemia in GD patients. Local hepcidin-ferroportin interaction was involved in this pathogenesis.
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http://dx.doi.org/10.3324/haematol.2017.177816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5865418PMC
April 2018

Iron metabolism and the role of the iron-regulating hormone hepcidin in health and disease.

Presse Med 2017 Dec 10;46(12 Pt 2):e272-e278. Epub 2017 Nov 10.

University Sorbonne Paris Cité, Paris Diderot University, Laboratory of Excellence GR-Ex, Inflammation Research Center (CRI), Inserm U1149/ERL 8252, Paris, France. Electronic address:

Although iron is vital, its free form is likely to be involved in oxidation-reduction reactions, leading to the formation of free radicals and oxidative stress. Living organisms have developed protein systems to transport free iron through the cell membranes and biological fluids and store it in a non-toxic and readily mobilizable form to avoid iron toxicity. Hepcidin plays a crucial role in maintaining iron homeostasis. Hepcidin expression is directly regulated by variations in iron intake and its repression leads to an increase in bioavailable serum iron level. However, in pathological situations, prolonged repression often leads to pathological iron overload. In this review, we describe the different molecular mechanisms responsible for the maintenance of iron metabolism and the consequences of iron overload. Indeed, genetic hemochromatosis and post-transfusional siderosis are the two main conditions responsible for iron overload. Long-term iron overload is deleterious, and treatment relies on venesection therapy for genetic hemochromatosis and chelation therapy for iron overload resulting from multiple transfusions.
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http://dx.doi.org/10.1016/j.lpm.2017.10.006DOI Listing
December 2017

Mutation in human elevates levels of aminolevulinate synthase and protoporphyrin IX to promote erythropoietic protoporphyria.

Proc Natl Acad Sci U S A 2017 09 5;114(38):E8045-E8052. Epub 2017 Sep 5.

Division of Hematology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115;

Loss-of-function mutations in genes for heme biosynthetic enzymes can give rise to congenital porphyrias, eight forms of which have been described. The genetic penetrance of the porphyrias is clinically variable, underscoring the role of additional causative, contributing, and modifier genes. We previously discovered that the mitochondrial AAA+ unfoldase ClpX promotes heme biosynthesis by activation of δ-aminolevulinate synthase (ALAS), which catalyzes the first step of heme synthesis. CLPX has also been reported to mediate heme-induced turnover of ALAS. Here we report a dominant mutation in the ATPase active site of human CLPX, p.Gly298Asp, that results in pathological accumulation of the heme biosynthesis intermediate protoporphyrin IX (PPIX). Amassing of PPIX in erythroid cells promotes erythropoietic protoporphyria (EPP) in the affected family. The mutation in inactivates its ATPase activity, resulting in coassembly of mutant and WT protomers to form an enzyme with reduced activity. The presence of low-activity CLPX increases the posttranslational stability of ALAS, causing increased ALAS protein and ALA levels, leading to abnormal accumulation of PPIX. Our results thus identify an additional molecular mechanism underlying the development of EPP and further our understanding of the multiple mechanisms by which CLPX controls heme metabolism.
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http://dx.doi.org/10.1073/pnas.1700632114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617249PMC
September 2017

Iron is a substrate of the chloroquine resistance transporter PfCRT in oocytes.

J Biol Chem 2017 09 2;292(39):16109-16121. Epub 2017 Aug 2.

the Center of Infectious Diseases, Parasitology, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany,

The chloroquine resistance transporter of the human malaria parasite , PfCRT, is an important determinant of resistance to several quinoline and quinoline-like antimalarial drugs. PfCRT also plays an essential role in the physiology of the parasite during development inside erythrocytes. However, the function of this transporter besides its role in drug resistance is still unclear. Using electrophysiological and flux experiments conducted on PfCRT-expressing oocytes, we show here that both wild-type PfCRT and a PfCRT variant associated with chloroquine resistance transport both ferrous and ferric iron, albeit with different kinetics. In particular, we found that the ability to transport ferrous iron is reduced by the specific polymorphisms acquired by the PfCRT variant as a result of chloroquine selection. We further show that iron and chloroquine transport via PfCRT is electrogenic. If these findings in the model extend to , our data suggest that PfCRT might play a role in iron homeostasis, which is essential for the parasite's development in erythrocytes.
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http://dx.doi.org/10.1074/jbc.M117.805200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625042PMC
September 2017

Cardiac iron overload in chronically transfused patients with thalassemia, sickle cell anemia, or myelodysplastic syndrome.

PLoS One 2017 3;12(3):e0172147. Epub 2017 Mar 3.

Hématologie clinique, Hôpital Saint Vincent de Paul, Université Catholique de Lille, Lille, France.

The risk and clinical significance of cardiac iron overload due to chronic transfusion varies with the underlying disease. Cardiac iron overload shortens the life expectancy of patients with thalassemia, whereas its effect is unclear in those with myelodysplastic syndromes (MDS). In patients with sickle cell anemia (SCA), iron does not seem to deposit quickly in the heart. Our primary objective was to assess through a multicentric study the prevalence of cardiac iron overload, defined as a cardiovascular magnetic resonance T2*<20 ms, in patients with thalassemia, SCA, or MDS. Patient inclusion criteria were an accurate record of erythrocyte concentrates (ECs) received, a transfusion history >8 ECs in the past year, and age older than 6 years. We included from 9 centers 20 patients with thalassemia, 41 with SCA, and 25 with MDS in 2012-2014. Erythrocytapharesis did not consistently prevent iron overload in patients with SCA. Cardiac iron overload was found in 3 (15%) patients with thalassemia, none with SCA, and 4 (16%) with MDS. The liver iron content (LIC) ranged from 10.4 to 15.2 mg/g dry weight, with no significant differences across groups (P = 0.29). Abnormal T2* was not significantly associated with any of the measures of transfusion or chelation. Ferritin levels showed a strong association with LIC. Non-transferrin-bound iron was high in the thalassemia and MDS groups but low in the SCA group (P<0.001). Hepcidin was low in thalassemia, normal in SCA, and markedly elevated in MDS (P<0.001). Two mechanisms may explain that iron deposition largely spares the heart in SCA: the high level of erythropoiesis recycles the iron and the chronic inflammation retains iron within the macrophages. Thalassemia, in contrast, is characterized by inefficient erythropoiesis, unable to handle free iron. Iron accumulation varies widely in MDS syndromes due to the competing influences of abnormal erythropoiesis, excess iron supply, and inflammation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172147PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5336214PMC
August 2017

Hemolytic anemia repressed hepcidin level without hepatocyte iron overload: lesson from Günther disease model.

Haematologica 2017 02 10;102(2):260-270. Epub 2016 Nov 10.

INSERM U1149/ERL CNRS 8252, Centre de Recherche sur l'Inflammation Paris Montmartre, 75018 Paris, France

Hemolysis occurring in hematologic diseases is often associated with an iron loading anemia. This iron overload is the result of a massive outflow of hemoglobin into the bloodstream, but the mechanism of hemoglobin handling has not been fully elucidated. Here, in a congenital erythropoietic porphyria mouse model, we evaluate the impact of hemolysis and regenerative anemia on hepcidin synthesis and iron metabolism. Hemolysis was confirmed by a complete drop in haptoglobin, hemopexin and increased plasma lactate dehydrogenase, an increased red blood cell distribution width and osmotic fragility, a reduced half-life of red blood cells, and increased expression of heme oxygenase 1. The erythropoiesis-induced Fam132b was increased, hepcidin mRNA repressed, and transepithelial iron transport in isolated duodenal loops increased. Iron was mostly accumulated in liver and spleen macrophages but transferrin saturation remained within the normal range. The expression levels of hemoglobin-haptoglobin receptor CD163 and hemopexin receptor CD91 were drastically reduced in both liver and spleen, resulting in heme- and hemoglobin-derived iron elimination in urine. In the kidney, the megalin/cubilin endocytic complex, heme oxygenase 1 and the iron exporter ferroportin were induced, which is reminiscent of significant renal handling of hemoglobin-derived iron. Our results highlight ironbound hemoglobin urinary clearance mechanism and strongly suggest that, in addition to the sequestration of iron in macrophages, kidney may play a major role in protecting hepatocytes from iron overload in chronic hemolysis.
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http://dx.doi.org/10.3324/haematol.2016.151621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5286934PMC
February 2017

A Variant of Peptide Transporter 2 Predicts the Severity of Porphyria-Associated Kidney Disease.

J Am Soc Nephrol 2017 Jun 28;28(6):1924-1932. Epub 2016 Dec 28.

Institut National pour la Santé et la Recherche Médicale (INSERM) U1147, Centre Universitaire des Saints Pères, Paris, France;

CKD occurs in most patients with acute intermittent porphyria (AIP). During AIP, -aminolevulinic acid (ALA) accumulates and promotes tubular cell death and tubulointerstitial damage. The human peptide transporter 2 (PEPT2) expressed by proximal tubular cells mediates the reabsorption of ALA, and variants of PEPT2 have different affinities for ALA. We tested the hypothesis that genotypes affect the severity and prognosis of porphyria-associated kidney disease. We analyzed data from 122 individuals with AIP who were followed from 2003 to 2013 and genotyped for At last follow-up, carriers of the genotype (higher affinity variant) exhibited worse renal function than carriers of the lower affinity variants and (mean±SD eGFR: 54.4±19.1, 66.6±23.8, and 78.1±19.9 ml/min per 1.73 m, respectively). Change in eGFR (mean±SD) over the 10-year period was -11.0±3.3, -2.4±1.9, and 3.4±2.6 ml/min per 1.73 m for , , and carriers, respectively. At the end of follow-up, 68% of carriers had an eGFR<60 ml/min per 1.73 m, compared with 37% of carriers and 15% of carriers. Multiple regression models including all confounders indicated that the genotype independently associated with an eGFR<60 ml/min per 1.73 m (odds ratio, 6.85; 95% confidence interval, 1.34 to 46.20) and an annual decrease in eGFR of >1 ml/min per 1.73 m (odds ratio, 3.64; 95% confidence interval, 1.37 to 9.91). Thus, a gene variant is predictive of the severity of a chronic complication of AIP. The therapeutic value of PEPT2 inhibitors in preventing porphyria-associated kidney disease warrants investigation.
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http://dx.doi.org/10.1681/ASN.2016080918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5461799PMC
June 2017

Reply.

Gastroenterology 2016 10 10;151(4):771-2. Epub 2016 Sep 10.

INSERM UMR1149 and Université Paris Diderot, Site Bichat, Sorbonne Paris Cité and Laboratory of Excellence, GR-Ex and Département de Génétique, Hôpital Bichat, Paris, France.

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http://dx.doi.org/10.1053/j.gastro.2016.09.002DOI Listing
October 2016

Rare microcytic anemias.

Bull Acad Natl Med 2016 Feb;200(2):335-347

Microcytic anemia is often due to disorder of globin genes. Here, we focus on rare monogenic microcytic anemias, We describe the diferent congenital forms that are due to mutations in genes implicated in iron homeostasis, the heme biosynthesis pathway, the cluster Fe-S biosynthesis pathway andmitochondrial proteins biosynthesis pathway. Among rare congenital microcytic anemias, most frequent forms are non syndromic sideroblastic anemias and iron refractory iron deficiency anemias (IRIDA). Sideroblastic anemias is characterized by mitochondrial iron overload and presence of ring sideroblasts in patient bone marrow.. IRIDA results from bi-allelic mutations of TMPRSS6 gene encoding Matriptase-2. Matriptase-2 protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. The next generation sequencing would be helpful to identify the genes implicated in unexplained rare anemias.
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February 2016

Heterozygous Mutations in BMP6 Pro-peptide Lead to Inappropriate Hepcidin Synthesis and Moderate Iron Overload in Humans.

Gastroenterology 2016 Mar 12;150(3):672-683.e4. Epub 2015 Nov 12.

AP-HP, Département de Génétique, Hôpital Bichat, Paris, France.

Background & Aims: Hereditary hemochromatosis is a heterogeneous group of genetic disorders characterized by parenchymal iron overload. It is caused by defective expression of liver hepcidin, the main regulator of iron homeostasis. Iron stimulates the gene encoding hepcidin (HAMP) via the bone morphogenetic protein (BMP)6 signaling to SMAD. Although several genetic factors have been found to cause late-onset hemochromatosis, many patients have unexplained signs of iron overload. We investigated BMP6 function in these individuals.

Methods: We sequenced the BMP6 gene in 70 consecutive patients with a moderate increase in serum ferritin and liver iron levels who did not carry genetic variants associated with hemochromatosis. We searched for BMP6 mutations in relatives of 5 probands and in 200 healthy individuals (controls), as well as in 2 other independent cohorts of hyperferritinemia patients. We measured serum levels of hepcidin by liquid chromatography-tandem mass spectrometry and analyzed BMP6 in liver biopsy specimens from patients by immunohistochemistry. The functions of mutant and normal BMP6 were assessed in transfected cells using immunofluorescence, real-time quantitative polymerase chain reaction, and immunoblot analyses.

Results: We identified 3 heterozygous missense mutations in BMP6 (p.Pro95Ser, p.Leu96Pro, and p.Gln113Glu) in 6 unrelated patients with unexplained iron overload (9% of our cohort). These mutations were detected in less than 1% of controls. p.Leu96Pro also was found in 2 patients from the additional cohorts. Family studies indicated dominant transmission. Serum levels of hepcidin were inappropriately low in patients. A low level of BMP6, compared with controls, was found in a biopsy specimen from 1 patient. In cell lines, the mutated residues in the BMP6 propeptide resulted in defective secretion of BMP6; reduced signaling via SMAD1, SMAD5, and SMAD8; and loss of hepcidin production.

Conclusions: We identified 3 heterozygous missense mutations in BMP6 in patients with unexplained iron overload. These mutations lead to loss of signaling to SMAD proteins and reduced hepcidin production. These mutations might increase susceptibility to mild-to-moderate late-onset iron overload.
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http://dx.doi.org/10.1053/j.gastro.2015.10.049DOI Listing
March 2016

The microbiota shifts the iron sensing of intestinal cells.

FASEB J 2016 Jan 14;30(1):252-61. Epub 2015 Sep 14.

*INSERM U1016, Institut Cochin, Paris, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8104, Paris, France; Université Paris Descartes and Université Paris Diderot, site Bichat, Sorbonne Paris Cité, Paris, France; Laboratory of Excellence GR-Ex, Paris, France; Institut National de la Recherche Agronomique, AgroParisTech, and Commensal and Probiotics-Host Interactions Laboratory, Unité Mixte de Recherche 1319, Microbiologie de l'Alimentation au Service de la Santé, Jouy-en-Josas, France; **INSERM Unité 1043-Centre de Physiopathologie de Toulouse Purpan and Université de Toulouse, Université Paul Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France; Centre National de la Recherche Scientifique Unité 5282, Toulouse, France; and INSERM Unité 1149, Centre de Recherches sur l'Inflammation, Paris, France

The amount of iron in the diet directly influences the composition of the microbiota. Inversely, the effects of the microbiota on iron homeostasis have been little studied. So, we investigate whether the microbiota itself may alter host iron sensing. Duodenal cytochrome b and divalent metal transporter 1, involved in apical iron uptake, are 8- and 10-fold, respectively, more abundant in the duodenum of germ-free (GF) mice than in mice colonized with a microbiota. In contrast, the luminal exporter ferroportin is 2-fold less abundant in GF. The overall signature of microbiota on iron-related proteins is similar in the colon. The colonization does not modify systemic parameters as plasma transferrin saturation (20%), plasma ferritin (150 ng/L), and liver (85 µg/g) iron load. Commensal organisms (Bacteroides thetaiotaomicron VPI-5482 and Faecalibacterium prausnitzii A2-165) and a probiotic strain (Streptococcus thermophilus LMD-9) led to up to 12-fold induction of ferritin in colon. Our data suggest that the intestinal cells of GF mice are depleted of iron and that following colonization, the epithelial cells favor iron storage. This study is the first to demonstrate that gut microbes induce a specific iron-related protein signature, highlighting new aspects of the crosstalk between the microbiota and the intestinal epithelium.
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http://dx.doi.org/10.1096/fj.15-276840DOI Listing
January 2016
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