Refractory Iron Deficiency Anemia Research Articles

Pharmacological Targeting of the Hepcidin/Ferroportin Axis.

The iron regulatory hormone hepcidin limits iron fluxes to the bloodstream by promoting degradation of the iron exporter ferroportin in target cells. Hepcidin insufficiency causes hyperabsorption of dietary iron, hyperferremia and tissue iron overload, which are hallmarks of hereditary hemochromatosis. Similar responses are also observed in iron-loading anemias due to ineffective erythropoiesis (such as thalassemias, dyserythropoietic anemias and myelodysplastic syndromes) and in chronic liver diseases. On the other hand, excessive hepcidin expression inhibits dietary iron absorption and leads to hypoferremia and iron retention within tissue macrophages. This reduces iron availability for erythroblasts and contributes to the development of anemias with iron-restricted erythropoiesis (such as anemia of chronic disease and iron-refractory iron-deficiency anemia). Pharmacological targeting of the hepcidin/ferroportin axis may offer considerable therapeutic benefits by correcting iron traffic. This review summarizes the principles underlying the development of hepcidin-based therapies for the treatment of iron-related disorders, and discusses the emerging strategies for manipulating hepcidin pathways.

PTH-034 Blinded Comparison of Magnetically Assisted Gastric Capsule Endoscopy and Conventional Endoscopy in Recurrent and Refractory Iron Deficiency Anaemia: A Feasibility Study: Abstract PTH-034 Table 1

Introduction Magnetically assisted capsule endoscopy (MACE) of the stomach has been demonstrated to be safe and feasible.1 The aim of this prospective feasibility study was to compare the ability of MACE to recognise gastric landmarks compared to conventional flexible endoscopy in patients with recurrent or refractory iron deficiency anaemia. Methods Twenty patients with recurrent/refractory iron deficiency anaemia were enrolled between Jan-Nov 2015. After conventional oesophagogastroduodenoscopy, MACE was performed using MiroCam Navi (Intromedic, Seoul, Korea). Visualisation of major upper gastrointestinal landmarks was graded on a 1–5 scale (1 = poor, 5 = excellent), abnormalities were recorded. Primary outcome measure: gastric landmark recognition. Secondary outcome measures: pathology detection, patient tolerance. Results MACE achieved satisfactory visualisation (grade 4 or 5) in 11% for the gastro-oesophageal junction, 21% for the cardia, 16% for the fundus, 79% for the anterior wall of the gastric body, 79% for the posterior wall, 79% for the greater curvature, 84% for the lesser curvature, 95% for the antrum and 89% for the pylorus. 38 pathological findings were identified (Table 1). Patients experienced less pain, discomfort and distress during MACE compared to flexible endoscopy (p = 0.0009, p = 0.001 and p = 0.006 respectively). Conclusion MACE can visualise gastric landmarks, detect a variety of gastric pathology and is better tolerated than conventional endoscopy. Capsule identification of hiatal hernias is difficult and may improve with experience.2 Better oesophageal visualisation is possible with other models and it seems likely that Mirocam Navi could be developed to this end. Proximal gastric views may be more reliable using a double ended capsule, better depth of illumination, and perhaps with control of capsule movement, all of which need further study before MACE becomes a viable alternative to conventional endoscopy. References 1 Hale MF, Drew K, Sidhu R, McAlindon ME. Does magnetically assisted capsule endoscopy improve small bowel capsule endoscopy completion rate? A randomised controlled trial. Endosc Int Open. 2016 Feb; 4(2):E215–21. 2 Marelli L, Jaboli FM, Jackson L, Palmer H, Erian G, Hamilton M, Epstein O. A pilot study comparing ESO-2 capsule endoscopy with conventional upper endoscopy for the assessment of uncomplicated heartburn and dyspepsia. Frontline Gastroenterol201;4:96–101. Disclosure of Interest None Declared

Limiting hepatic Bmp-Smad signaling by matriptase-2 is required for erythropoietin-mediated hepcidin suppression in mice

AbstractHepcidin, the main regulator of iron homeostasis, is repressed when erythropoiesis is acutely stimulated by erythropoietin (EPO) to favor iron supply to maturing erythroblasts. Erythroferrone (ERFE) has been identified as the erythroid regulator that inhibits hepcidin in stress erythropoiesis. A powerful hepcidin inhibitor is the serine protease matriptase-2, encoded by TMPRSS6, whose mutations cause iron refractory iron deficiency anemia. Because this condition has inappropriately elevated hepcidin in the presence of high EPO levels, a role is suggested for matriptase-2 in EPO-mediated hepcidin repression. To investigate the relationship between EPO/ERFE and matriptase-2, we show that EPO injection induces Erfe messenger RNA expression but does not suppress hepcidin in Tmprss6 knockout (KO) mice. Similarly, wild-type (WT) animals, in which the bone morphogenetic protein–mothers against decapentaplegic homolog (Bmp-Smad) pathway is upregulated by iron treatment, fail to suppress hepcidin in response to EPO. To further investigate whether the high level of Bmp-Smad signaling of Tmprss6 KO mice counteracts hepcidin suppression by EPO, we generated double KO Bmp6-Tmprss6 KO mice. Despite having Bmp-Smad signaling and hepcidin levels that are similar to WT mice under basal conditions, double KO mice do not suppress hepcidin in response to EPO. However, pharmacologic downstream inhibition of the Bmp-Smad pathway by dorsomorphin, which targets the BMP receptors, improves the hepcidin responsiveness to EPO in Tmprss6 KO mice. We concluded that the function of matriptase-2 is dominant over that of ERFE and is essential in facilitating hepcidin suppression by attenuating the BMP-SMAD signaling.

Anemia in Adult Celiac Disease; Presentation with Iron Deficiency Anemia Masked by Colon Cancer

An elderly physician with iron deficiency anemia and early stage colon cancer localized in the cecum was treated successfully with laparoscopic right hemicolectomy. Despite treatment, her iron deficiency anemia persisted. Subsequent investigations revealed occult celiac disease that completely resolved with a gluten-free diet alone. Iron deficiency anemia in celiac disease may have multiple causes including reduced duodenal iron absorption because of reduced absorptive surface area, alterations or mutations in iron regulatory proteins critical for normal iron absorption, superimposed occult blood loss from different causes including benign and malignant small bowel ulceration, and low grade intravascular hemolysis. Although iron deficiency anemia may be the sole presenting clinical manifestation of occult celiac disease without other typical symptoms, such as diarrhea or weight loss, a very thorough gastrointestinal assessment is essential to exclude other causes of iron deficiency anemia. Conversely, persistent or refractory iron deficiency anemia may represent a clue to unrecognized celiac disease, even in the elderly.

The mutual control of iron and erythropoiesis.

Iron is essential for hemoglobin synthesis during terminal erythropoiesis. To supply adequate iron the carrier transferrin is required together with transferrin receptor endosomal cycle and normal mitochondrial iron utilization. Iron and iron protein deficiencies result in different types of anemia. Iron-deficiency anemia is the commonest anemia worldwide due to increased requirements, malnutrition, chronic blood losses and malabsorption. Mutations of transferrin, transferrin receptor cycle proteins, enzymes of the first step of heme synthesis and iron sulfur cluster biogenesis lead to rare anemias, usually accompanied by iron overload. Hepcidin plays an indirect role in erythropoiesis by controlling plasma iron. Inappropriately high hepcidin levels characterize the rare genetic iron-refractory iron-deficiency anemia (IRIDA) and the common anemia of chronic disease. Iron modulates both effective and ineffective erythropoiesis: iron restriction reduces heme and alpha-globin synthesis that may be of benefit in thalassemia. This review relies on the analysis of the most recent literature and personal data. Erythropoiesis controls iron homeostasis, by releasing erythroferrone that inhibits hepcidin transcription to increase iron acquisition in iron deficiency, hypoxia and EPO treatment. Erythroferrone, produced by EPO-stimulated erythropoiesis, inhibits hepcidin only when the activity of BMP/SMAD pathway is low, suggesting that EPO somehow modulates the latter signaling. Erythroblasts sense circulating iron through the second transferrin receptor (TFR2) that, in animal models, modulates the sensitivity of the erythroid cells to EPO. The advanced knowledge of the regulation of systemic iron homeostasis and erythropoiesis-mediated hepcidin regulation is leading to the development of targeted therapies for anemias and iron disorders.

Iron-refractory iron deficiency anemia

The major causes of iron deficiency anemia (IDA) include iron loss due to bleeding, increased iron requirements, and decreased iron absorption by the intestine. The most common cause of IDA in Japanese women is iron loss during menstruation. Autoimmune atrophic gastritis and Helicobacter pylori infection can also cause IDA by reducing intestinal iron absorption. In addition to these common etiologies, germline mutations of TMPRSS6 can cause iron-refractory IDA (IRIDA). TMPRSS6 encodes matriptase-2, a membrane-bound serine protease primarily expressed in the liver. Functional loss of matriptase-2 due to homozygous mutations results in an increase in the expression of hepcidin, which is the key regulator of systemic iron homeostasis. The serum hepcidin increase in turn leads to a decrease in iron supply from the intestine and macrophages to erythropoietic cells. IRIDA is microcytic and hypochromic, but decreased serum ferritin is not observed as in IDA. IRIDA is refractory to oral iron supplementation, but does respond to intravenous iron supplementation to some extent. Because genetic testing is required for the diagnoses of IRIDA, a considerable number of cases may go undiagnosed and may thus be overlooked.

Hepcidin.

Hepcidin is an iron-regulating peptide hormone made in the liver. It controls the delivery of iron to blood plasma from intestinal cells absorbing iron, from erythrocyte-recycling macrophages, and from iron-storing hepatocytes. Hepcidin acts by binding to and inactivating the sole cellular iron exporter, ferroportin, which delivers iron to plasma from all iron-transporting cells. In a classical endocrine feedback system, hepcidin production is stimulated by plasma iron and iron stores. Reflecting a likely role of hepcidin in innate immunity, hepcidin is also induced by inflammation. Increased erythropoietic activity suppresses hepcidin, which leads to increased iron absorption and release of iron from stores, matching iron supply to increased demand. This suppression of hepcidin is in part mediated by erythroferrone, a hormone produced by erythropoietin-stimulated erythroblasts. Hereditary hemochromatosis is caused by hepcidin deficiency or resistance to hepcidin, and hepcidin deficiency also mediates the hyperabsorption of iron in β-thalassemia and other iron-loading anemias. Pathologically increased concentrations of hepcidin are seen in iron-refractory iron deficiency anemia, in anemia of inflammation, and anemia of chronic kidney disease where increased hepcidin limits the availability of iron for erythropoiesis. Its central involvement in a variety of iron disorders makes hepcidin an important target for diagnostic and therapeutic applications.

Response to parenteral iron therapy distinguish unexplained refractory iron deficiency anemia from iron‐refractory iron deficiency anemia

We evaluated that response to parenteral iron therapy could be helpful in distinguishing the types of iron deficiency anemia. This study analyzed responses to IV iron sucrose therapy of 15 children with unexplained refractory iron deficiency anemia (URIDA). We compared the results at diagnosis, 6 weeks and 6 months after the therapy. Results were compared with responses of 11 patients' results with iron-refractory iron deficiency anemia (IRIDA) from our previous study. Six weeks after the start of treatment, ferritin, MCV, MCH and Hb values were in normal range in 10 patients. The increase in Hb, MCH, MCV, and ferritin values ranged 2.6-3.5 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. In five patients, Hb, MCH, and MCV mean (range) values [11.2 g/dL (11-12.2), 24.5 pg (24-25.6), and 67 fL (65-70)] were nearly normal but ferritin mean (range) values [9.8 ng/mL (8-11)] were below normal. Six weeks after the start of treatment, Hb, MCH, MCV and ferritin values of patients with IRIDA were increased. The increase in Hb, MCH, MCV, and ferritin values ranged 0.8-2.7 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. IRIDA is only partially responsive to parenteral iron supplementation. In conclusion, this study demonstrated that the response to intravenous iron therapy for the URIDA cases improved blood parameters more effectively than hereditary IRIDA. Response to parenteral iron therapy would be helpful to distinguish unexplained refractory IDA from hereditary IRIDA for clinicians who do not have access to hepcidin or TMPRS6 mutation analysis.

Iron deficiency anemia refractory to iron preparations.

Most patients with iron deficiency anemia are treated effectively with oral iron preparations. However, a small number of these patients are refractory to such treatments, even when the pathologic condition underlying the anemia is concurrently treated. The pathological basis for this refractoriness can be explained by several factors, including malabsorption of iron, e.g. atrophic gastritis, deficiency of other hematopoietic vitamins or minerals, e.g. vitamin B12 or zinc, other undiagnosed anemic disorders, e.g. renal anemia or hematopoietic diseases, as well as certain hereditary disorders of iron metabolism, e.g. iron refractory iron deficiency anemia (IRIDA) caused by genetic mutation of the TMPRSS6 gene. This review focuses on the diagnosis and pathoetiology of iron deficiency anemia that is refractory to conventional oral iron preparations.

Colonic Metastasis with Anemia Leading to a Diagnosis of Primary Lung Adenocarcinoma.

Metastasis occurs with 50% of lung carcinomas, most commonly to lymph nodes, adrenal glands, liver, bone, and brain. It is extremely rare for lung cancer to present with symptoms of a gastrointestinal metastasis and even more so pertaining to the colon. To the best of our knowledge, only 12 such cases have been reported in the literature. We describe a case of a 71-year-old female presenting with refractory iron deficiency anemia that was found to have a lesion in the transverse colon. Pathology revealed adenocarcinoma of the lung and a subsequent lung lesion was discovered in a retrograde fashion.

Native Valve Streptococcus bovis Endocarditis and Refractory Transfusion Dependent Iron Deficiency Anaemia Associated with Concomitant Carcinoma of the Colon: A Case Report and Review of the Literature.

Streptococcus bovis is found as a commensal organism in human gut and may become opportunistically pathogenic. Infective endocarditis is one of the commonest modes of presentation of this infection. The association between Streptococcus bovis endocarditis and colorectal cancer is well recognized. We report a case of Streptococcus bovis endocarditis along with a refractory iron deficiency anaemia associated with concomitant carcinoma of ascending colon in a 63-year-old male. Cooccurrence of these two conditions may cause a challenge in the management. Considering the strong association of colon cancer with Streptococcus bovis endocarditis, a detailed screening colonoscopy is mandatory following the diagnosis of the latter.

Inactivation of Tmprss6 Hampers Hepcidin Inhibition By Erythroferrone through Upregulation of the BMP-SMAD Pathway

IntroductionErythroferrone (ERFE), a member of the C1q-TNF protein family produced by erythropoietin (EPO)-stimulated erythroid cells, has been recently identified as the erythroid regulator that suppresses hepcidin (Kautz et al., 2014). In the liver, the main hepcidin inhibitor is TMPRSS6, the only known in vivo inhibitor of the BMP-SMAD pathway since its inactivation causes Iron Refractory Iron Deficiency Anemia (IRIDA) (Finberg et al., 2008), a genetic disorder due to inappropriately high hepcidin. We have previously demonstrated that inactivation of Tmprss6 in thalassemia mice rescues iron overload and ameliorate anemia by increasing hepcidin, notwithstanding high Epo (Nai et al., 2012) and Erfe (Silvestri et al., ASH Meeting 2014) thus suggesting that Tmprss6 is indispensable for hepcidin inhibition by the erythroid regulator(s).MethodsTo analyze BM and spleen erythroid differentiation, Ter119+ cells were separated according to Forward Scatter (FSC) value and Cd44 expression, as previously described (Liu et al., 2013). Expression of Erfe, Epo, hepcidin and BMP-SMAD target genes were evaluated by qRT-PCR and iron parameters by standard methods (Pagani et al., 2011). We have analyzed different animal models after a single (200U) EPO injection: 1) Tmprss6 KO mice and wild type littermates fed an iron balanced (IB) and iron deficient (ID), diet; 2) wild type mice with activated BMP-SMAD pathway by iron dextran (1g/kg) treatment; 3) Tmprss6 KO animals with the BMP-SMAD pathway inhibited by 12.5 μg/g dorsomorphin. Both males and females mice were analyzed at 8-10 weeks of age and sacrificed 15 hours after EPO treatment.ResultsEPO administration increases bone marrow (BM) erythroid precursors in all mice models. In the spleen erythroid precursors are not further upregulated by EPO in ID and Tmprss6 KO mice, since already high in basal conditions likely due to stress erythropoiesis. Erfe expression is upregulated in basal conditions in BM and spleen of ID and Tmprss6 KO mice, which have high serum Epo levels, and is further increased by EPO treatment in all models. As expected, hepcidin is strongly reduced in ID animals, whereas it is high in Tmprss6 KO mice. EPO injection strongly inhibits hepcidin both in IB and ID mice but not in Tmprss6 KO animals, notwithstanding the upregulation of Erfe. This suggests that lack of Tmprss6 impairs the Erfe-mediated hepcidin inhibition. To evaluate the contribution of Tmprss6 and the BMP signaling to Erfe function, we modulated the BMP pathway before EPO challenge. We activated the signaling by means of iron dextran injection in wild type mice and we inhibited the hyperactive pathway of Tmprss6 KO animals by using the BMP receptor inhibitor dorsomorphin. Neither iron dextran injection nor dorsomorphin treatment impairs Erfe activation by EPO that equals that observed in saline treated animals. In iron loaded mice with hyperactive BMP signaling, hepcidin was not inhibited by Erfe. Dorsomorphin treatment in Tmprss6 KO animals rescues the hepcidin responsiveness to Erfe.ConclusionsWe confirm that the BMP-SMAD pathway is dispensable for Erfe-mediated hepcidin inhibition since Erfe decreases hepcidin in ID, when the pathway is suppressed. However, activation of the BMP-SMAD pathway consequent to iron loading or to the loss of Tmprss6 hampers the hepcidin downregulation by Erfe, suggesting that the Tmprss6 function, and not Tmprss6 per se, is essential to facilitate the Erfe-dependent hepcidin inhibition by blunting the BMP-SMAD signaling. DisclosuresNo relevant conflicts of interest to declare.

Hemin: A Salvage Treatment for a Patient with Severe Auto-Immune Hemolytic Anemia and Reticulocytopenia

Reticulocytopenia concurrent with AIHA is a potentially life threatening condition. It has been described with involvement of certain allo or auto antibodies (Kell; Ge3; U) and parvovirus B19 infection. The hemolysis, uncompensated by reticulocytosis, may require transfusion of multiple RBC units as a supportive measure.We report here the case of a 61-year old woman admitted to a teaching hospital on February 3rd 2014 for the sudden appearance of symptoms and hematological and biochemical markers suggesting hemolytic anemia with reticulocytopenia. The initial serologic workup was negative. No incompatibility has been observed when first RBC units were cross-matched, but hemolysis of transfused red cells was paramount. An intensive immunosuppressive therapy regimen began on day 5.On the 8th day of her hospital stay a significant drop in platelet count was also observed: a bone marrow tap and biopsy were performed and a blood specimen sent to the Hema-Quebec Reference Laboratory. Cytology examination described a hyperplasia of megakaryocytes and erythroid precursors with karyorrhexis. An auto-anti-Ge3 was identified by serology and the Ge3 antigen confirmed by genotyping. At that point in time (day 8) she had received 25 units of Ge3+ red cells to maintain her Hb>4.5gm.On day 10, the hemolytic process began abating without any improvement of reticulocytosis nor Hb level. Six units of rare Ge3 negative blood were found. The survival of the first 5 units after transfusion was better but shorter than expected. With only one unit left we convinced Health Canada to authorize the compassionate use of Normosang (Human Hemin) by referring to an in vitro experiment published in Transfusion, Volume 53, p2134-40 October 2013.The first dose was given on day 26 along with on day 27, the 6th Ge3 negative unit for a Hb level at 4.2gm. No other transfusion had to be administered thereafter. On day 28 the reticulocytes started to increase (along with the platelets and Hb level) and reached above normal levels on day 29, culminating at around 450 on day 35 and remaining elevated as long as hemin therapy was maintained. They dropped abruptly at normal levels 7 days after hemin arrest decided because of important iron accumulation described by MRI in spleen and liver. But cessation of Normosang could put the patient at risk of relapse since the Ab was still detected. In order to minimize this possibility a splenectomy was performed 4 days later and a long-term immunosuppressive drug added. One month after splenectomy the antibody was only weakly detectable in eluate. Thereafter, Hb continued to rise reaching 11.6gm in mid-May and above 13.0 during the summer. Currently she is under a phlebotomy program to reduce her iron stores down to normal values. This would facilitate the use of Normosang again if relapse occurs.Discussion - Previous reports indicated that both auto and allo anti-Ge3 antibodies can cause various degrees of the atypical clinical picture and laboratory abnormalities presented here. Also their capacity to inhibit the differentiation of erythroid precursors and cause reticulocytopenia is probably linked to the position of Ge3 antigen on glycophorin C and D.The monograph of Normosang indicates that exogenous hemin can replace endogenous heme for various biological functions. But its only recognized therapeutic indication is the treatment or prevention of acute attack of hepatic porphyria. With respect to erythropoiesis, studies on cell cultures have shown that human hemin stimulates formation of red blood cell line precursors. The case presented adds information about its in vivo ability of lifting inhibition of erythropoiesis induced by an antibody. The precise pathways involved for those actions remains to be elucidated. But following this case, it seems of interest to study the possibility that this drug could be of value for sparing many transfusions of RBC units used at the present time as a supportive measure not only in certain AIHAs with reticulocytopenia but also during treatment of other hematological conditions (autologous hematopoietic stem cell transplants for instance). Also, its use could be beneficial for prevention or treatment of refractory iron deficiency anemia in infancy due to loss-of-function mutation in the TMPRSS6 gene, as recently described. We are currently discussing with clinicians the modalities of patient recruitment in order to carry out clinical studies on these issues. [Display omitted] DisclosuresOff Label Use: Hemin recognized therapeutic indication is the treatment or prevention of acute attack of hepatic porphyria.

Intravenous iron sucrose for children with iron deficiency anemia: a single institution study.

Intravenous iron sucrose is not recommended by its manufacturers for use in children despite extensive safety and efficacy data in adults. We reviewed the experience of our department between January, 2011 and February, 2014 with the use of intravenous iron sucrose in children ≤14 years of age who failed in oral iron therapy for iron deficiency anemia (IDA). Twelve children (6 females) aged 1.2-14 years (median age 8.9 years) received at least one dose of intravenous iron sucrose. Ten patients had IDA inadequately treated or non-responsive to oral iron therapy. One patient received therapy for blood transfusion avoidance and one for presumed iron refractory iron deficiency anemia (IRIDA). Iron sucrose infusions were given on alternate days up to three times per week. The number of infusions per patient ranged from 2 to 6 (median, 3), the individual doses from 100 mg to 200 mg (median, 200 mg), and the total doses from 200 mg to 1200 mg (median, 400 mg). Iron sucrose was effective in raising the hemoglobin concentration to normal in all patients with IDA, i.e., from 7.6±2.38 g/dL to 12.4±0.64 g/dL, within 31-42 days after the first infusion. The single patient with IRIDA demonstrated a 1.8 g/dL rise. Injection site disorders in three cases and transient taste perversion in one case were the only side effects. Intravenous iron sucrose appears to be safe and very effective in children with IDA who do not respond or cannot tolerate oral iron therapy.

Iron-refractory iron deficiency anemia.

Iron is essential for life because it is indispensable for several biological reactions, such as oxygen transport, DNA synthesis, and cell proliferation. Over the past few years, our understanding of iron metabolism and its regulation has changed dramatically. New disorders of iron metabolism have emerged, and the role of iron as a cofactor in other disorders has begun to be recognized. The study of genetic conditions such as hemochromatosis and iron-refractory iron deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited to improve treatment of both genetic and acquired iron disorders. IRIDA is caused by mutations in TMPRSS6, the gene encoding matriptase-2, which downregulates hepcidin expression under conditions of iron deficiency. The typical features of this disorder are hypochromic, microcytic anemia with a very low mean corpuscular volume of erythrocytes, low transferrin saturation, no (or inadequate) response to oral iron, and only a partial response to parenteral iron. In contrast to classic iron deficiency anemia, serum ferritin levels are usually low-normal, and serum or urinary hepcidin levels are inappropriately high for the degree of anemia. Although the number of cases reported thus far in the literature does not exceed 100, this disorder is considered the most common of the “atypical” microcytic anemias. The aim of this review is to share the current knowledge on IRIDA and increase awareness in this field.

The role of TMPRSS6 polymorphisms in iron deficiency anemia partially responsive to oral iron treatment

Iron refractory iron deficiency anemia (IRIDA) is a rare hereditary disease caused by mutations in TMPRSS6 gene encoding Matriptase-2, a negative regulator of hepcidin transcription. Up to now, 53 IRIDA patients from 35 families with different ethnic origins have been reported and 41 TMPRSS6 mutations have been identified. TMPRSS6 polymorphisms are more frequent than mutations, and have been associated with variation in iron and hematologic parameters. Our study evaluated their presence in 113 subjects with iron deficiency anemia (IDA) partially responsive to oral iron therapy and in 50 healthy blood donors. Thalassemic trait was diagnosed in 38 patients. Sequencing analysis of TMPRSS6 gene revealed that the frequency of several polymorphisms was markedly different between IDA subjects and controls. In particular, the V736A TMPRSS6 polymorphism was associated to moderately lower hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin levels, and in thalassemia carriers with marked anemia and microcytosis. A new variant-H448R- and two uncommon polymorphisms -A719T and V795I- were also identified. These results indicate that TMPRSS6 polymorphisms are more frequent in subjects with persistent IDA than in healthy controls, and in thalassemia carriers V736A variant may account for lower hemoglobin and MCV levels. Further studies in larger court of patients are necessary to identify potential haplotypes and polymorphisms responsible for low response to oral iron treatment and may be useful for planning a correct iron supplementation.

Functional analysis of matriptase-2 mutations and domains: insights into the molecular basis of iron-refractory iron deficiency anemia.

Mutations in the TMPRSS6 gene are associated with severe iron-refractory iron deficiency anemia resulting from an overexpression of hepcidin, the key regulator of iron homeostasis. The matriptase (MT)-2 protein (encoded by the TMPRSS6 gene) regulates hepcidin expression by cleaving hemojuvelin [HJV/hemochromatosis type 2 (HFE2)], a bone morphogenetic protein (BMP) coreceptor in the hepcidin regulatory pathway. We investigated the functional consequences of five clinically associated TMPRSS6 variants and the role of MT-2 protein domains by generating epitope-tagged mutant and domain-swapped MT-2-MT-1 (encoded by the ST14 gene) chimeric constructs and expressing them in HepG2/C3A cells. We developed a novel cell culture immunofluorescence assay to assess the effect of MT-2 on cell surface HJV expression levels, compatible with HJV cleavage. The TMPRSS6 variants Y141C, I212T, G442R, and C510S were retained intracellularly and were unable to inhibit BMP6 induction of hepcidin. The R271Q variant, although it has been associated with iron-refractory iron deficiency anemia, appears to remain functional. Analysis of the chimeric constructs showed that replacement of sperm protein, enterokinase, and agrin (SEA), low-density-lipoprotein receptor class A (LDLRA), and protease (PROT) domains from MT-2 with those from MT-1 resulted in limited cell surface localization, while the complement C1r/C1s, Uegf, Bmp1 (CUB) domain chimera retained localization at the cell surface. The SEA domain chimera was able to reduce cell surface HJV expression, while the CUB, LDLRA, and PROT domain chimeras were not. These studies suggest that the SEA and LDLRA domains of MT-2 are important for trafficking to the cell surface and that the CUB, LDLRA, and PROT domains are required for cleavage of HJV.

Bevacizumab : un nouveau succès dans la maladie de Rendu-Osler

IntroductionHereditary hemorrhagic telangiectasia (HHT), is a rare, hereditary vascular dysplasia, characterized by recurrent epistaxis, mucocutaneous telangiectasias and visceral arteriovenous malformations. The vascular endothelial growth factor VEGF seems to play a crucial role in the pathogenesis of this disease. Recently bevacizumab, a humanized monoclonal VEGF inhibitor, has shown promise in treating patients with HHT. Case reportA 66-year-old man, having HHT since the age of 30 years with recurrent epistaxis related to telangiectasia at the nasal septum and chronic iron deficiency anemia requiring frequent blood transfusions with iron infusions. The assessment of his disease showed septal perforation, telangiectasis in the proximal jejunum and terminal ileum, and pulmonary arteriovenous malformations. There was no improvement, despite iron infusions, repeated blood transfusions and cauterization. The patient was treated with bevacizumab at a dose of 5mg/kg/infusion every 2 weeks and was given 6 cycles. Bevacizumab, was effective without side effects. DiscussionIt has been hypothesized that HHT is related to an imbalanced state between antiangiogenic factors and proangiogenic factors. Mutations of 3 genes are actually identified in HHT: ENG, ACVRL1, MADH4. The management of patients with HHT currently based on screening for visceral arteriovenous malformations and symptomatic measures are often disappointing. However, the angiogenic nature of this disease suggests an interesting therapy by using angiogenesis inhibitor. Therefore, bevacizumab was introduced as a potential therapy for HHT. Some clinical cases or small series report the efficacy of bevacizumab, in HHT with recurrent epistaxis, refractory iron deficiency anemia, gastrointestinal bleeding and also in liver vascular malformations with high cardiac output failure. ConclusionThe use of modulators of angiogenesis such as bevacizumab is a possible therapeutic target in HHT.

Changing face and clinical features of celiac disease in children.

The aim of this study was to analyze and compare the epidemiological and presenting features, clinical patterns, and complications of celiac disease (CD) in children. The clinical charts of children with CD were retrospectively analyzed. Data for children who presented during the first time period (January 2005-October 2008; group 1) were compared to those of children who presented during the second time period (November 2008-April 2012; group 2). Group 1 and 2 consisted of 96 and 95 children, respectively. There were no differences in gender distribution, weight, or height z-scores between the two groups. Mean age at the time of diagnosis in group 2 (9.3 ± 4.5 years) was significantly higher than in group 1 (6.9 ± 3.9 years; P < 0.001). Non-classical presentation was more frequent in group 2 (P = 0.01). Associated disorders were observed in 49 children (25.7%) overall. There were significantly more children with type 1 diabetes mellitus in group 2 (P = 0.030). In all, 11 patients (5.8%) were overweight (either obese or at risk of obesity) at presentation. Isolated short stature was the presenting feature in 15 children (7.9%) overall, but was more frequently observed in group 2 (P = 0.003). In total, 15 patients (7.9%) presented with refractory iron deficiency anemia; the frequency was similar in both groups. Dual-energy X-ray absorptiometry was performed in 102 patients, and 82 (80.4%) had metabolic bone disease (MBD). The mode of presentation and clinical features of CD in childhood continue to change. Of note, a substantial percentage of patients were overweight at presentation. MBD is a frequent complication, necessitating routine evaluation.

A competitive enzyme-linked immunosorbent assay specific for murine hepcidin-1: correlation with hepatic mRNA expression in established and novel models of dysregulated iron homeostasis.

Mice have been essential for distinguishing the role of hepcidin in iron homeostasis. Currently, investigators monitor levels of murine hepatic hepcidin-1 mRNA as a surrogate marker for the bioactive hepcidin protein itself. Here, we describe and validate a competitive, enzyme-linked immunosorbent assay that quantifies hepcidin-1 in mouse serum and urine. The assay exhibits a biologically relevant lower limit of detection, high precision, and excellent linearity and recovery. We also demonstrate correlation between serum and urine hepcidin-1 values and validate the competitive enzyme-linked immunosorbent assay by analyzing plasma hepcidin response of mice to physiological challenges, including iron deficiency, iron overload, acute blood loss, and inflammation. Furthermore, we analyze multiple murine genetic models of iron dysregulation, including β-thalassemia intermedia (Hbb(th3/+)), hereditary hemochromatosis (Hfe(-/-), Hjv(-/-), and Tfr2(Y245X/Y245X)), hypotransferrinemia (Trf(hpx/hpx)), heterozygous transferrin receptor 1 deficiency (Tfrc(+/-)) and iron refractory iron deficiency anemia (Tmprss6(-/-) and Tmprss6(hem8/hem8)). Novel compound iron metabolism mutants were also phenotypically characterized here for the first time. We demonstrate that serum hepcidin concentrations correlate with liver hepcidin mRNA expression, transferrin saturation and non-heme liver iron. In some circumstances, serum hepcidin-1 more accurately predicts iron parameters than hepcidin mRNA, and distinguishes smaller, statistically significant differences between experimental groups.