Systemic Iron Deficiency Research Articles

Normalization of Fetal Cerebral and Hepatic Iron by Parental Iron Therapy to Pregnant Rats with Systemic Iron Deficiency without Anemia.

Iron (Fe) is a co-factor for enzymes of the developing brain necessitating sufficient supply. We investigated the effects of administering ferric derisomaltose/Fe isomaltoside (FDI) subcutaneously to Fe-deficient (ID) pregnant rats on cerebral and hepatic concentrations of essential metals and the expression of iron-relevant genes. Pregnant rats subjected to ID were injected with FDI on the day of mating (E0), 14 days into pregnancy (E14), or the day of birth (postnatal (P0)). The efficacy was evaluated by determination of cerebral and hepatic Fe, copper (Cu), and zinc (Zn) and gene expression of ferroportin, hepcidin, and ferritin H + L in pups on P0 and as adults on P70. Females fed an ID diet (5.2 mg/kg Fe) had offspring with significantly lower cerebral and hepatic Fe compared to female controls fed a standard diet (158 mg/kg Fe). Cerebral Cu increased irrespective of supplying a standard diet or administering FDI combined with the standard diet. Hepatic hepcidin mRNA was significantly lower following ID. Cerebral hepcidin mRNA was hardly detectable irrespective of iron status. In conclusion, administering FDI subcutaneously to ID pregnant rats on E0 normalizes fetal cerebral and hepatic Fe. When applied at later gestational ages, supplementation with additional Fe to the offspring is needed to normalize cerebral and hepatic Fe.

Prognostic Role of Tissue Iron Deficiency Measured by sTfR Levels in Heart Failure Patients without Systemic Iron Deficiency or Anemia.

Background. Iron deficiency (ID) is a significant, high-prevalence comorbidity in chronic heart failure (HF) that represents an independent predictor of a worse prognosis. However, a clear-cut diagnosis of ID in HF patients is not assured. The soluble transferrin receptor (sTfR) is a marker that reflects tissue-level iron demand and may be an early marker of ID. However, the impact of sTfR levels on clinical outcomes in non-anemic HF patients with a normal systemic iron status has never been evaluated. Methods. This is a post hoc analysis of an observational, prospective cohort study of 1236 patients with chronic HF of which only those with normal hemoglobin levels and a normal systemic iron status were studied. The final cohort consisted of 215 patients. Tissue ID was defined as levels of sTfR > 75th percentile (1.65 mg/L). Our aim was to describe the association between sTfR and clinical outcomes (all-cause death and HF hospitalization) and to explore its association with a wide array of serum biomarkers. Results. The sTfR level (HR 1.48, 95% CI 1.13-1.96, p = 0.005) and tissue ID (HR 2.14, 95% CI 1.22-3.75, p = 0.008) was associated with all-cause death. However, we found no association between sTfR levels and the risk of HF hospitalization. Furthermore, high sTfR levels were associated with a worse biomarker profile indicating myocardial damage (troponin and NT-proBNP), systemic inflammation (CRP and albumin), and impaired erythropoiesis (erythropoietin). Conclusions. In this cohort, the presence of tissue ID defined by sTfR levels is an independent factor for all-cause death in patients with normal systemic iron parameters.

Identification of three mechanistic pathways for iron-deficient heart failure.

Current understanding of iron-deficient heart failure is based on blood tests that are thought to reflect systemic iron stores, but the available evidence suggests greater complexity. The entry and egress of circulating iron is controlled by erythroblasts, which (in severe iron deficiency) will sacrifice erythropoiesis to supply iron to other organs, e.g. the heart. Marked hypoferraemia (typically with anaemia) can drive the depletion of cardiomyocyte iron, impairing contractile performance and explaining why a transferrin saturation < ≈15%-16% predicts the ability of intravenous iron to reduce the risk of major heart failure events in long-term trials (Type 1 iron-deficient heart failure). However, heart failure may be accompanied by intracellular iron depletion within skeletal muscle and cardiomyocytes, which is disproportionate to the findings of systemic iron biomarkers. Inflammation- and deconditioning-mediated skeletal muscle dysfunction-a primary cause of dyspnoea and exercise intolerance in patients with heart failure-is accompanied by intracellular skeletal myocyte iron depletion, which can be exacerbated by even mild hypoferraemia, explaining why symptoms and functional capacity improve following intravenous iron, regardless of baseline haemoglobin or changes in haemoglobin (Type 2 iron-deficient heart failure). Additionally, patients with advanced heart failure show myocardial iron depletion due to both diminished entry into and enhanced egress of iron from the myocardium; the changes in iron proteins in the cardiomyocytes of these patients are opposite to those expected from systemic iron deficiency. Nevertheless, iron supplementation can prevent ventricular remodelling and cardiomyopathy produced by experimental injury in the absence of systemic iron deficiency (Type 3 iron-deficient heart failure). These observations, taken collectively, support the possibility of three different mechanistic pathways for the development of iron-deficient heart failure: one that is driven through systemic iron depletion and impaired erythropoiesis and two that are characterized by disproportionate depletion of intracellular iron in skeletal and cardiac muscle. These mechanisms are not mutually exclusive, and all pathways may be operative at the same time or may occur sequentially in the same patients.

Spatial IMA1 regulation restricts root iron acquisition on MAMP perception.

Iron is critical during host-microorganism interactions1-4. Restriction of available iron by the host during infection is an important defence strategy, described as nutritional immunity5. However, this poses a conundrum for externally facing, absorptive tissues such as the gut epithelium or the plant root epidermis that generate environments that favour iron bioavailability. For example, plant roots acquire iron mostly from the soil and, when iron deficient, increase iron availability through mechanisms that include rhizosphere acidification and secretion of iron chelators6-9. Yet, the elevated iron bioavailability would also be beneficial for the growth of bacteria that threaten plant health. Here we report that microorganism-associated molecular patterns such as flagellin lead to suppression of root iron acquisition through a localized degradation of the systemic iron-deficiency signalling peptide Iron Man 1 (IMA1) in Arabidopsis thaliana. This response is also elicited when bacteria enter root tissues, but not when they dwell on the outer root surface. IMA1 itself has a role in modulating immunity in root and shoot, affecting the levels of root colonization and the resistance to a bacterial foliar pathogen. Our findings reveal an adaptive molecular mechanism of nutritional immunity that affects iron bioavailability and uptake, as well as immune responses.

The Effect of Diet Composition on the Post-operative Outcomes of Roux-en-Y Gastric Bypass in Mice.

Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied. A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8weeks. After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis. Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

Iron Dyshomeostasis and Mitochondrial Function in the Failing Heart: A Review of the Literature.

Cardiac contraction and relaxation require a substantial amount of energy provided by the mitochondria. The failing heart is adenosine triphosphate (ATP)- and creatine-depleted. Studies have found iron is involved in almost every aspect of mitochondrial function, and previous studies have shown myocardial iron deficiency in heart failure (HF). Many clinicians advocated intravenous iron repletion for HF patients meeting the conventional criteria for systemic iron deficiency. While clinical trials showed improved quality of life, iron repletion failed to significantly impact survival or significant cardiovascular adverse events. There is evidence that in HF, labile iron is trapped inside the mitochondria causing oxidative stress and lipid peroxidation. There is also compelling preclinical evidence demonstrating the detrimental effects of both iron overload and depletion on cardiomyocyte function. We reviewed the mechanisms governing myocardial and mitochondrial iron content. Mitochondrial dynamics (i.e., fusion, fission, mitophagy) and the role of iron were also investigated. Ferroptosis, as an important regulated cell death mechanism involved in cardiomyocyte loss, was reviewed along with agents used to manipulate it. The membrane stability and iron content of mitochondria can be altered by many agents. Some studies are showing promising improvement in the cardiomyocyte function after iron chelation by deferiprone; however, whether the in vitro and in vivo findings will be reflected on on clinical grounds is still unclear. Finally, we briefly reviewed the clinical trials on intravenous iron repletion. There is a need for more well-simulated animal studies to shed light on the safety and efficacy of chelation agents and pave the road for clinical studies.

Iron chelation and supplementation: A comparison in the management of inflammatory bowel disease using drosophila

AimsInflammatory Bowel Disease (IBD) is associated with systemic iron deficiency and has been managed with iron supplements which cause adverse side effects. Conversely, some reports highlight iron depletion to ameliorate IBD. The underlying intestinal response and comparative benefit of iron depletion and supplementation in IBD is unknown. The aims of this work were to characterize and compare the effects of iron supplementation and iron depletion in IBD. Main methodsIBD was induced in Drosophila melanogaster using 3 % dextran sodium sulfate (DSS) in diet for 7 days. Using this model, we investigated the impacts of acute iron depletion (using bathophenanthroline disulfonate, BPS) and supplementation (using ferrous sulphate, FS), before and after IBD induction, on gut iron homeostasis, cell death, gut permeability, inflammation, antioxidant defence, antimicrobial response and several fly phenotypes. Key findingsDSS decreased fly mass (p < 0.001), increased gut permeability (p < 0.001) and shortened lifespan (p = 0.035) compared to control. The DSS-fed flies also showed significantly elevated lipid peroxidation (p < 0.001), and the upregulated expression of apoptotic marker- drice (p < 0.001), tight junction protein – bbg (p < 0.001), antimicrobial peptide – dpta (p = 0.002) and proinflammatory cytokine – upd2 (p < 0.001). BPS significantly (p < 0.05) increased fly mass and lifespan, decreased gut permeability, decreased lipid peroxidation and decreased levels of drice, bbg, dpta and upd2 in IBD flies. This iron chelation (using BPS) showed better protection from DSS-induced IBD than iron supplementation (using FS). Preventive and curative interventions, by BPS or FS, also differed in outcomes. SignificanceThis may inform precise management strategies aimed at tackling IBD and its recurrence.

Soluble transferrin receptor as a marker of tissue iron deficiency: impact on health-related quality of life in patients with heart failure without systemic iron deficiency or anaemia

Abstract Background Soluble receptor of transferrin (sTfR) is a marker of tissue iron status and may help to inform on subtle iron depletion and increased iron demand of functional proteins at tissular level even in the absence of systemic iron deficiency or anaemia. Raised sTfR levels have been associated with of all-cause mortality and impaired exercise capacity in patients with heart failure (HF). However, the impact quality of life (QoL) has not been evaluated. Purpose The aim of our study was to describe the association between sTfR as a marker of increased iron demand and tissue iron deficiency and QoL in non-anaemic patients with HF and normal systemic iron status. Methods We conducted an observational, prospective, cohort study of 1120 consecutive patients with chronic HF (DAMOCLES study). For the current sub-study, we selected all patients form the DAMOCLES cohort that had normal haemoglobin levels and normal systemic iron and available QoL data. Tissue ID was defined as levels of sTfR&amp;gt; 75th percentile (1.63mg/L). To assess QoL, we used the Minnesota Living with Heart Failure Questionnaire (MLHFQ). The primary endpoint was the overall summary score (OSS) of the MLHFQ instrument self-administered at inclusion in the study. The unadjusted parametric and non-parametric associations between sTfR and the MLHFQ OSS scores were explored using General Additive Models (GAM). Univariate and multivariate linear regression models were constructed to explore the associations between sTfR levels and tissue ID and the QoL scores. All models were adjusted by age, sex, and prognostic factors such as LVEF, NYHA, NT-proBNP levels and iron status parameters among other well-known determinants of HF severity. Results The final study cohort consisted in 206 patients. Mean age was 70±12 years, mean LVEF was 43±15% and 61 (30%) were women. Mean sTfR values were 1.42±0.66 mg/L. Tissue ID was present in 54 patients (26%). Mean MLHFQ OSS were 42±26. Global QoL was significantly worse in patients with tissue ID compared to patients without tissue ID (51±27 vs. 39±20, p-value=0.006, respectively). In unadjusted GAM models (Figure 1) showed a direct and significant association between increased iron demand and worse global QoL with a linear p-value&amp;lt;0.0001. As shown in Table 1, higher sTfR were associated with higher MLHFQ OSS scores in unadjusted models. These findings were confirmed in forward stepwise multivariate linear regression models (Table 1). Conclusions In a cohort of HF patients without iron deficiency or anaemia, higher levels of sTfR indicating increased iron demand and tissue ID were associated with worse QoL.

Soluble transferrin receptor as a marker of tissue iron deficiency: impact on cardiac, systemic, hematinic and neurohormonal biomarkers in patients with heart failure without systemic iron deficiency

Abstract Background Soluble receptor of transferrin (sTfR) is a marker of tissue iron status and may help to inform on subtle iron depletion and increased iron demand at tissular level even in the absence of overt systemic iron deficiency or anaemia. In this regard, the impact of raised sTfR levels as a marker of subtle tissue iron deficiency (ID) on serum biomarkers in non-anaemic HF patients with otherwise normal systemic iron status has not been evaluated. Purpose The aim of our study was to describe the association between sTfR as a marker of increased iron demand and tissue iron deficiency on cardiac, systemic, neurohormonal and hematinic biomarkers in non-anaemic patients with HF and normal systemic iron status. Methods We conducted an observational, prospective, cohort study of 1120 consecutive patients with chronic HF regardless the level of LVEF (DAMOCLES study). Patients were included if they had normal haemoglobin levels (≥12 g/dL), normal systemic iron status (serum iron &amp;gt;33 µg/dL, ferritin &amp;gt;100ng/mL and % transferrin saturation &amp;gt;20%) and available biomarker data. sTfR was measured with the Beckman Coulter enzyme immunoassay (higher levels indicate increased iron demand). The primary objective was to explore the association between sTfR and NT-proBNP levels. Secondary objectives were to explore the association between sTfR, and a wide array of serum biomarkers. Pearson’s correlation coefficient (r) was used to estimate correlations in bivariate analyses. The sex-and-age adjusted associations between sTfR, and the biomarkers were explored using General Additive Models (GAM) and linear regression models. Results The final study cohort consisted in 215 patients. Mean age was 70±12 years, mean LVEF was 43±15% and 62 (29%) were women. Mean sTfR values were 1.42±0.66 mg/L. In the whole cohort, median [Q1-Q3] NT-proBNP (pg/mL) was 1,125[587-2,668]. Log-transformed sTfR (log[sTfR]) showed significant correlations with log[NT-proBNP] (r=0.230; p-value=0.001), log[cTnT] (r=0.197; p-value=0.028), log[albumin](r=-0.221; p-value=0.001), C-reactive protein (r=0.215; p-value=0.002), serum erythropoietin levels, MCH (r=-0.247; p-value&amp;lt;0.001) and MCHC (r=-0.209; p-value&amp;lt;0.001). As shown in Table 1, these findings were confirmed in multivariate age-and-sex adjusted linear regression models. In age-and-sex adjusted Generalized Additive Models (GAM) (Figure 1), we confirmed that higher levels of sTfR were associated with increased levels of biomarkers indicating cardiac damage (cTnT, NT-proBNP), active inflammatory status (C-reactive protein) and increased cellular stimulation in response to tissue hypoxia (endogenous erythropoietin). Conclusions In a cohort of HF patients without iron deficiency or anaemia, higher levels of sTfR indicating increased iron demand and tissue ID were associated with a worse biomarker profile indicating early subclinical cardiac and/or systemic damage even in the absence of overt systemic iron deficiency or anaemia.

Soluble transferrin receptor as a marker of tissue iron deficiency: impact on exercise capacity and functional class in patients with heart failure without systemic iron deficiency or anaemia

Abstract Background Soluble receptor of transferrin (sTfR) is a marker of tissue iron status and may help to inform on subtle iron depletion and increased iron demand at tissular level even in the absence of overt systemic iron deficiency or anaemia. In this regard, the impact of raised sTfR levels as a marker of subtle tissue ID on functional limitation and submaximal exercise capacity in non-anaemic HF patients with normal systemic iron status has not been evaluated. Purpose To describe the association between sTfR as a marker of increased iron demand and tissue iron deficiency on submaximal exercise capacity, estimated with the distance walked in the 6-minutes walking test (6MWT), and symptoms of functional limitation (evaluated with the NYHA functional class) in non-anaemic patients with HF and normal systemic iron status. Methods We conducted an observational, prospective, cohort study of 1120 consecutive patients with chronic HF regardless the level of LVEF (DAMOCLES study). Patients included had a normal haemoglobin levels (≥12 g/dL), a normal systemic iron status (serum iron &amp;gt;33 µg/dL, ferritin &amp;gt;100ng/mL and % transferrin saturation &amp;gt;20%) and an available 6-minute walking test data. Tissue ID was defined as levels of sTfR &amp;gt;75th percentile (1.63mg/L). The primary endpoint was the distance walked in the 6MWT at inclusion in the study. The unadjusted associations between sTfR and the distance walked in the 6MWT were explored using General Additive Models (GAM), uni/multivariate linear regression models and also uni/multivariate binary regression models. All models were adjusted by age, sex, and prognostic factors such as LVEF, NYHA, NT-proBNP levels and iron status parameters among other well-known determinants of HF severity. Results The final study cohort consisted in 202 patients from the DAMOCLES study. Mean age was 70±12 years, mean LVEF was 43±15% and 57 (28%) were women. Mean sTfR values were 1.42±0.66 mg/L. Tissue ID was present in 54 patients (25%). In the whole cohort, mean 6MWT distance was 287±168 m. 6MWT distance was significantly worse in patients with tissue ID compared to patients without tissue ID (206±179m vs. 314±155, p-value&amp;lt;0.0001, respectively). Likewise, impaired submaximal exercise capacity was more common in patients with tissue ID (32, 64%) compared to patients without tissue ID (59, 39%, p-value=0.003). In unadjusted GAM models (Figure 1) we observed a significant association between increased iron demand (higher levels of sTfR) and lower distance achieved in the 6MWT. As shown in Table 1, higher sTfR levels were associated with lower distance in the 6MWT in unadjusted linear regression and binary logistic regression models. Conclusions In a cohort of HF patients without iron deficiency or anaemia, higher levels of sTfR indicating increased iron demand and tissue ID were associated with worse submaximal exercise capacity and tended to experience more functional limitations according to NYHA functional class.

Soluble transferrin receptor as a marker of tissue iron deficiency: impact on clinical outcomes in patients with heart failure without systemic iron deficiency or anaemia

Abstract Background Soluble receptor of transferrin (sTfR) is a marker of tissue iron status and may help to inform on subtle iron depletion and increased iron demand of functional proteins at tissular level even in the absence of overt systemic iron deficiency or anaemia. Raised sTfR levels have been associated with increased risk of all-cause mortality in general population and in patients with heart failure (HF). However, the prognostic significance of raised sTfR levels in non-anaemic HF patients with otherwise normal systemic iron status has not been evaluated. Purpose The aim of our study was to describe the association between sTfR as a marker of increased iron demand and tissue iron deficiency on outcomes in non-anaemic patients with HF and normal systemic iron status. Methods We conducted an observational, prospective, cohort study of 1120 consecutive patients with chronic HF (DAMOCLES study). For the current sub-study, we selected all patients form the DAMOCLES cohort that had a complete iron status evaluation including sTfR, normal haemoglobin levels and normal systemic iron status. Tissue ID was defined as levels of sTfR&amp;gt; 75th percentile (1.63mg/L). The primary and secondary endpoints were all-cause mortality and HF hospitalization respectively. Multivariate Cox proportional hazards models were constructed to explore the associations between tissue ID and the studied outcomes. In addition, the multivariate parametric and non-parametric associations between sTfR and the β estimated risk of the occurrence of the primary and secondary endpoints were explored using General Additive Models (GAM). All models were adjusted by age, sex, and prognostic factors such as LVEF, NYHA, NT-proBNP levels and iron status parameters among other well-known determinants of HF severity. Results The final study cohort consisted in 215 patients from the DAMOCLES study. Mean age was 70±12 years, mean LVEF was 43±15% and 62 (29%) were women. Mean sTfR values were 1.42±0.66 mg/L. Tissue ID was present in 54 patients (25%). Hospital readmission occurred in 55 patients (25.6%) and death occurred in 60 (27.9%). In multivariate Cox proportional hazards models (table 1) higher levels of sTfR and Tissue ID were significantly associated with the risk all-cause death. This association was not observed for HF readmission. As shown in figure 1 panel A, adjusted GAM showed there was a significant linear association between higher levels of sTfR and the mortality risk. Moreover, the adjusted cumulative risk of all-cause death (Figure 1 panel B) confirmed higher risk of death among patients with tissue ID compared to patients’ levels of sTfR≤ the 75th percentile with early divergence of the curves during follow-up. Conclusions In a cohort of HF patients without iron deficiency or anaemia, higher levels of sTfR indicating tissue ID were associated with increased risk of mortality. This association was linear and was not observed for HF readmission.

Durability of Hematocrit Control in Polycythemia Vera with the First-in-Class Hepcidin Mimetic Rusfertide: Two-Year Follow up Results from the Revive Study

Background: Polycythemia vera (PV) is a myeloproliferative neoplasm associated with uncontrolled erythrocytosis, systemic symptoms, and an increased risk of thromboembolic and cardiovascular complications largely driven by uncontrolled hematocrit (HCT) levels. Rusfertide is a hepcidin mimetic that controls red blood cell production in PV patients by limiting iron availability. The REVIVE trial (PTG-300-04; NCT04057040) is investigating rusfertide and consists of three stages. Eligibility criteria: diagnosis of PV; ≥3 therapeutic phlebotomies (TP)s in the 28 weeks prior to enrollment with or without concurrent cytoreductive therapies (CYTO). As reported previously, adding rusfertide to standard of care PV treatments optimally controls HCT levels and decreases the need for TP (Kuykendall et al., HemaSphere, 2022;6:(S3):1766; Kremyanskaya et al. EHA2023; Abstract LB2710). Herein, we report results from the ongoing open-label extension (OLE) from REVIVE (Part 3) and explore the long-term durability of response to rusfertide. Methods: During Part 1 (Week 1-29), treatment with rusfertide was initiated at 20 mg and individually titrated to control hematocrit (&amp;lt;45%); the median was 40 mg/wk and relatively stable after achieving a therapeutic dose. In Part 2 (Week 29-41), the blinded randomized withdrawal phase, patients were randomized to either continue rusfertide or to matching placebo. Any randomized patient who responded or did not respond was allowed to participate in Part 3 (3-yr OLE). The investigators can adjust doses of rusfertide and CYTO as needed to manage PV symptoms and blood counts. During Part 3, the hematocrit, erythrocytes, leukocytes, platelets, and ferritin are being assessed to determine long-term durability of response to rusfertide. Results: In Part 1 of REVIVE, 70 patients were enrolled, 59 were randomized, and 58 continued into the OLE (Part 3). As of July 11, 2023, of the 70 enrolled patients, 57 (81.4%) patients have been treated for ≥1 year, 46 (65.7%) for ≥1.5 years, and 24 (34.3%) for ≥2 years. For subjects continuing in Part 3, the median age was 57 years (range, 27-77); 41 (70.7%) were men, and 17 (29.3%) were women. Thirty-two (55.2%) of the 58 subjects were treated with phlebotomy (PHL); 26 (44.8%) were receiving concurrent therapy with CYTO. All patients were essentially phlebotomy-free while on rusfertide treatment. Mean platelet counts increased initially on average within 4 weeks following initiation of rusfertide but subsequently stabilized at approximately 30% increase by week 9 (Figure 1); platelets didn't increase with the increase in rusfertide doses either. The increased platelet counts were not associated with any bleeding or thrombotic events. Leukocyte counts remained stable. Treatment with rusfertide resulted in the consistent maintenance of hematocrit below 45% and an overall decrease in erythrocyte counts (Figure 2). This effect was lost temporarily for patients randomized to placebo during Part 2 and returned after resuming rusfertide treatment. Prior to enrollment, iron-related parameters were consistent with systemic iron deficiency (mean [±SE] ferritin 18.7 [±4.3] µg/L). Rusfertide treatment resulted in an improvement of serum ferritin towards normal levels (mean [±SE] ferritin 148.6 [±18.6] µg/L at Cycle 15 during the OLE) (Figure 2). Rusfertide was generally well tolerated; 80% of treatment-emergent adverse events (TEAEs) were grade 1-2, 20% were grade 3, and none were grade 4 or 5. The most common TEAEs were injection site reactions (ISRs), which were localized and grade 1-2 in severity and decreased in incidence with continued treatment. Six (8.6%) TEAEs led to treatment discontinuation. Conclusions: The REVIVE OLE demonstrated that rusfertide can provide long-term control of HCT, without phlebotomy, in patients with PV receiving TP with or without CYTO. Ferritin improved with rusfertide dosing and other lineages, after an initial increase in platelet counts both platelets and leucocyte counts remained stable during rusfertide treatment. Rusfertide was added to the current standard of care and was generally well-tolerated; most TEAEs were grade 1 or 2.

Iron deficiency in myocardial ischaemia: molecular mechanisms and therapeutic perspectives.

Systemic iron deficiency (SID), even in the absence of anaemia, worsens the prognosis and increases mortality in heart failure (HF). Recent clinical-epidemiological studies, however, have shown that a myocardial iron deficiency (MID) is frequently present in cases of severe HF, even in the absence of SID and without anaemia. In addition, experimental studies have shown a poor correlation between the state of systemic and myocardial iron. MID in animal models leads to severe mitochondrial dysfunction, alterations of mitophagy, and mitochondrial biogenesis, with profound alterations in cardiac mechanics and the occurrence of a fatal cardiomyopathy, all effects prevented by intravenous administration of iron. This shifts the focus to the myocardial state of iron, in the absence of anaemia, as an important factor in prognostic worsening and mortality in HF. There is now epidemiological evidence that SID worsens prognosis and mortality also in patients with acute and chronic coronary heart disease and experimental evidence that MID aggravates acute myocardial ischaemia as well as post-ischaemic remodelling. Intravenous administration of ferric carboxymaltose (FCM) or ferric dextrane improves post-ischaemic adverse remodelling. We here review such evidence, propose that MID worsens ischaemia/reperfusion injury, and discuss possible molecular mechanisms, such as chronic hyperactivation of HIF1-α, exacerbation of cytosolic and mitochondrial calcium overload, amplified increase of mitochondrial [NADH]/[NAD+] ratio, and depletion of energy status and NAD+ content with inhibition of sirtuin 1-3 activity. Such evidence now portrays iron metabolism as a core factor not only in HF but also in myocardial ischaemia.

Bone marrow sinusoidal endothelial cells are a site of Fgf23 upregulation in a mouse model of iron deficiency anemia.

Iron deficiency is a potent stimulator of fibroblast growth factor 23 (FGF23), a hormonal regulator of phosphate and vitamin D metabolism, that is classically thought to be produced by bone-embedded osteocytes. Here, we show that iron-deficient transmembrane serine protease 6 knockout (Tmprss6-/-) mice exhibit elevated circulating FGF23 and Fgf23 messenger RNA (mRNA) upregulation in the bone marrow (BM) but not the cortical bone. To clarify sites of Fgf23 promoter activity in Tmprss6-/- mice, we introduced a heterozygous enhanced green fluorescent protein (eGFP) reporter allele at the endogenous Fgf23 locus. Heterozygous Fgf23 disruption did not alter the severity of systemic iron deficiency or anemia in the Tmprss6-/- mice. Tmprss6-/-Fgf23+/eGFP mice showed green fluorescence in the vascular regions of BM sections and showed a subset of BM endothelial cells that were GFPbright by flow cytometry. Mining of transcriptomic data sets from mice with normal iron balance revealed higher Fgf23 mRNA in BM sinusoidal endothelial cells (BM-SECs) than that in other BM endothelial cell populations. Anti-GFP immunohistochemistry of fixed BM sections from Tmprss6-/-Fgf23+/eGFP mice revealed GFP expression in BM-SECs, which was more intense than in nonanemic controls. In addition, in mice with intact Tmprss6 alleles, Fgf23-eGFP reporter expression increased in BM-SECs following large-volume phlebotomy and also following erythropoietin treatment both exvivo and invivo. Collectively, our results identified BM-SECs as a novel site for Fgf23 upregulation in both acute and chronic anemia. Given the elevated serum erythropoietin in both anemic models, our findings raise the possibility that erythropoietin may act directly on BM-SECs to promote FGF23 production during anemia.

Distinct regulation of iron homeostasis in rat heart and liver in response to systemic iron deficiency

Chronic heart failure (HF) is characterized by severe cardiac mitochondrial dysfunction. Cellular energetic function is importantly regulated by iron since mitochondrial enzymes involved in oxidative phosphorylation, antioxidative defense and oxygen transport require iron-containing cofactors (heme, Fe-S clusters). In HF, systemic iron deficiency (ID) shows high prevalence (30–50%) and is associated with worse exercise capacity and increased mortality. Human and animal studies showed discordant results concerning iron content in failing heart, even reporting mitochondrial iron overload in some instance. This leads to a controversy of using iron chelation or iron supplementation as metabolic therapy for HF. Our aim was to investigate the regulation of key actors of cellular iron metabolism in the left (LV) and the right (RV) ventricles of two rat models of systemic ID. A comparative study was also performed in the liver, the main iron storage organ known to sense systemic ID. We developed two rat models of systemic ID without anaemia and cardiac remodelling, using low iron diet for 60 days, combined either with two distinct blood withdrawals at day 0 and 30 or with iron chelator deferiprone from day 1 to 60. Control rats were fed on a normal iron diet. Rats were sacrificed at day 60, serum and tissue iron contents were determined using a photometric colorimetric method. mRNA and protein levels of transferrin receptor 1 (TfR1), L-ferritin (L-Ft) and ferroportin (Fpn), involved in iron uptake, storage and export respectively were measured in biopsies of RV, LV and liver. Liver hepcidin, regulating systemic iron homeostasis, was analysed at mRNA level as well as cardiac hepcidin required for autonomous cellular iron homeostasis. Our main results showed that LV and RV maintained their iron content in a physiological range while the liver drastically decreased its iron pool in response to ID. In this condition, the RV exhibited a post-transcriptional regulation of both TfR1, L-Ft and Fpn similarly to the one found in the liver. In contrast, the LV showed a post-translational regulation of TfR1, a potential post-transcriptional regulation of L-Ft and no regulation for Fpn in ID. Our study showed that both ventricles initiate an adaptative response to maintain their physiological iron pool under systemic ID. These results should be confirmed in a HF model with systemic ID to better establish the benefits of iron chelation or supplementation in HF patients.

Defective iron homeostasis and hematological abnormalities in Niemann-Pick disease type C1.

Background: Niemann-Pick disease type C1 (NPC1) is a neurodegenerative lysosomal storage disorder characterized by the accumulation of multiple lipids in the late endosome/lysosomal system and reduced acidic store calcium. The lysosomal system regulates key aspects of iron homeostasis, which prompted us to investigate whether there are hematological abnormalities and iron metabolism defects in NPC1. Methods: Iron-related hematological parameters, systemic and tissue metal ion and relevant hormonal and proteins levels, expression of specific pro-inflammatory mediators and erythrophagocytosis were evaluated in an authentic mouse model and in a large cohort of NPC patients. Results: Significant changes in mean corpuscular volume and corpuscular hemoglobin were detected in Npc1 -/- mice from an early age. Hematocrit, red cell distribution width and hemoglobin changes were observed in late-stage disease animals. Systemic iron deficiency, increased circulating hepcidin, decreased ferritin and abnormal pro-inflammatory cytokine levels were also found. Furthermore, there is evidence of defective erythrophagocytosis in Npc1 -/- mice and in an in vitro NPC1 cellular model. Comparable hematological changes, including low normal serum iron and transferrin saturation and low cerebrospinal fluidferritin were confirmed in NPC1 patients. Conclusions: These data suggest loss of iron homeostasis and hematological abnormalities in NPC1 may contribute to the pathophysiology of this disease.

Comparative analysis of the functional properties of human and mouse ferroportin.

Ferroportin (Fpn)-expressed at the plasma membrane of macrophages, enterocytes, and hepatocytes-mediates the transfer of cellular iron into the blood plasma. Under the control of the iron-regulatory hormone hepcidin, Fpn serves a critical role in systemic iron homeostasis. Although we have previously characterized human Fpn, a great deal of research in iron homeostasis and disorders uses mouse models. By way of example, the flatiron mouse, a model of classical ferroportin disease, bears the mutation H32R in Fpn and is characterized by systemic iron deficiency and macrophage iron retention. The flatiron mouse also appears to exhibit a manganese phenotype, raising the possibility that mouse Fpn serves a role in manganese metabolism. At odds with this observation, we have found that human Fpn does not transport manganese, so we considered the possibility that a species difference could explain this discrepancy. We tested the hypothesis that mouse but not human Fpn can transport manganese and performed a comparative analysis of mouse and human Fpn. We examined the functional properties of human Fpn, mouse Fpn, and mutant mouse Fpn by using radiotracer assays in RNA-injected Xenopus oocytes. We found that neither mouse nor human Fpn transports manganese. Mouse and human Fpn share identical properties with respect to substrate profile, calcium dependence, optimal pH, and hepcidin sensitivity. We have also demonstrated that Fpn is not an ATPase pump. Our findings validate the use of mouse models of ferroportin function in iron homeostasis and disease.

Assessment of Vitamin A Status in Patients with Iron Deficiency Anemia

Introduction: Iron and vitamin A deficiency are two very prevalent and easily preventable nutrient deficiencies. This study was conducted to assess vitamin A status in patients with iron deficiency anemia and to further study the correlation of vitamin A status with biochemical markers of iron deficiency. Materials and Method: Eighty patients with iron deficiency anemia were enrolled and investigated for a complete blood count, an iron profile, liver, and kidney function tests and plasma retinol binding protein levels. The mean age of patients was 31.14 ± 11.33 years, with a range of 16 to 62 years. Results: Mean hemoglobin was 7.19 ± 2.1 g/dL. Serum iron, ferritin, and transferrin saturation were low in all patients, while total iron binding capacity (TIBC) was elevated in only 74 patients (94.81%). Nineteen patients (23.8%) had vitamin A deficiency, with a mean retinol binding protein (RBP) 0.53 ± 0.13 µmol/L. Vitamin A deficient patients had a mean hemoglobin of 6.8±2.14 gm/dL, mean corpuscular volume (MCV) 71.35 ± 8.86 fL, a mean corpuscular hemoglobin (MCH) 19.43±4.36 pg, mean corpuscular hemoglobin concentration (MCHC) 25.44±4.92 gm/dL, serum iron of 28.21 ± 9.73 mcg/dL, serum ferritin 13.04 ± 12.41 ng/mL, transferrin saturation 6.81 ± 3.07%, and TIBC 427.85 ± 78.57 mcg/dL. Among vitamin A deficient patients, RBP had positive correlation with serum iron and transferrin saturation; while, simultaneously showing negative correlation with serum ferritin and TIBC. Conclusion: Vitamin A deficiency affects iron metabolism, causing abnormal iron trapping and systemic iron deficiency, thus worsening the clinical profile of iron deficiency anemia. This study guides us to screen iron deficiency anemia patients for the concomitant vitamin A deficiency for efficient treatment of such patients.

Hepcidin and its multiple partners: Complex regulation of iron metabolism in health and disease.

The peptide hormone hepcidin is central to the regulation of iron metabolism, influencing the movement of iron into the circulation and determining total body iron stores. Its effect on a cellular level involves binding ferroportin, the main iron export protein, preventing iron egress and leading to iron sequestration within ferroportin-expressing cells. Hepcidin expression is enhanced by iron loading and inflammation and suppressed by erythropoietic stimulation. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis as occurs in anemia of chronic inflammation. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload such as hereditary hemochromatosis and iron loading anemias. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we assess the complex regulation of hepcidin, delineate the many binding partners involved in its regulation, and present an update on the development of hepcidin agonists and antagonists in various clinical scenarios.

Preliminary Results of a Phase-2 Clinical Trial of the ALK-2 Inhibitor Ker-047 for Treatment of Iron Refractory Iron Deficiency Anemia

Background: Iron refractory iron deficiency anemia (IRIDA) is a rare autosomal recessive disorder, caused by a genetic defect in TMPRSS6. This results in increased signaling through the bone morphogenic protein (BMP)/sons of mothers against decapentaplegic (SMAD) pathway, leading to disproportionally high levels of hepcidin relative to body iron status. Hepcidin reduces iron transport to the plasma by degrading the cellular iron exporter ferroportin, resulting in systemic iron deficiency and microcytic anemia. Symptomatic interventions such as intravenous iron administration results in iron sequestration in the reticular endothelial system (RES) and generally only a partial response of hemoglobin concentrations. Further, the potential long-term adverse effects of chronic intravenous iron therapy and associated elevated RES-iron levels are unknown in these patients. Blood transfusion can be administered in cases of severe symptomatic anemia but is generally avoided due to transfusion-related risks. Currently, there is an unmet need for more effective, safe, convenient, and direct-acting treatments for IRIDA. Given the central role of aberrant BMP/SMAD signaling in hepcidin production, selective inhibition of the BMP receptor ALK2 to reduce hepcidin represents a rational approach to target a precipitating factor of IRIDA. Preclinical studies in the TMPRSS6 siRNA knockdown mouse model of IRIDA demonstrated that treatment with a selective ALK2 inhibitor reduced hepcidin, increased serum iron, and ameliorated anemia. KER-047 is a novel, oral, investigational, small-molecule kinase inhibitor with potent and selective inhibitory activity against the ALK2 receptor. In a Phase 1 clinical trial, single-ascending and multiple-ascending doses of KER-047 administered to healthy participants resulted in robust decreases from baseline in hepcidin levels, increases in serum iron and transferrin saturation (TSAT), decreases in serum ferritin, and increases in reticulocyte hemoglobin content (Ret-He). Based on these observations, KER-047 was advanced to Phase 2 clinical trials. Aims: The primary objective of this ongoing Phase 2 clinical trial is to evaluate the safety and tolerability of ascending doses of KER-047 in participants with IRIDA. Secondary objectives include evaluation of pharmacokinetic (PK) and pharmacodynamic (PD) parameters. Methods: This is a 2-part open label, dose escalation and dose expansion trial. Part 1 (dose escalation) consists of up to 4 ascending dose cohorts starting with 25 mg q.d. Part 2 will be the dose expansion phase with safety as the primary focus. Patients diagnosed with IRIDA may enroll in all cohorts in Parts 1 and 2. Key inclusion criteria include diagnosis of IRIDA based on a homozygous or compound heterozygous TMPRSS6 genotype, a TSAT <15%, a ferritin level 50-700 µg/L and hemoglobin <13.8 g/dL (males) or <12.7g/dL (females) and signed informed consent. Patients are excluded if they have received IV iron treatment within 28 days prior to trial entry. Participants will be treated once daily with KER-047 for a 2-week period, followed by a 2-week washout period. Data are analyzed by using descriptive statistics. Results: At the time of this abstract submission, one participant had enrolled in the first dose-expansion cohort (KER-047 25mg q.d.). This participant reported intermittent dizziness, however no serious adverse events were observed during treatment. Hemoglobin concentration and mean corpuscular volume remained stable. Ret-He increased by day 5 of treatment. Ferritin levels decreased during treatment and returned to baseline levels after the 2-week treatment period. TSAT/hepcidin ratio, which is characteristically below reference intervals in IRIDA patients, was slightly increased but returned to baseline levels after 2-weeks treatment. Conclusion: Data are preliminary and limited to a single participant thus far in whom KER-047 25mg q.d. was well tolerated. Changes in red cell and iron parameters at this low dose support development of KER-047 as an agent to potentially address an underlying cause of IRIDA. At the time of this abstract submission, two additional patients are scheduled for screening to complete the first dose cohort. We anticipate data from the total of three patients in time for the presentation to further characterize safety of KER-047 and substantiate effects on iron metabolism. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal