Zinc Supplementation Enhances the Hematopoietic Activity of Erythropoiesis-Stimulating Agents but Not Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitors.

Since zinc is involved in many aspects of the hematopoietic process, zinc supplementation can reduce erythropoiesis-stimulating agents (ESAs) in patients undergoing hemodialysis. However, it remains unclear whether hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) have similar reduction effects. HIF-PHI stabilizes HIF, which promotes hematopoiesis, although HIF-1α levels are downregulated by zinc. This study aimed to investigate the effect of zinc supplementation on the hematopoietic effect of HIF-PHI in patients undergoing hemodialysis. Thirty patients undergoing maintenance hemodialysis who underwent periods of treatment with roxadustat or darbepoetin alfa during the past 3 years were retrospectively observed. Participants who underwent periods with and without zinc supplementation were selected, with nine treated with darbepoetin alfa and nine treated with roxadustat. Similarly to the ESA responsiveness index (ERI), the hematopoietic effect of zinc supplementation was determined by the HIF-PHI responsiveness index (HRI), which was calculated by dividing the HIF-PHI dose (mg/week) by the patient's dry weight (kg) and hemoglobin level (g/L). Zinc supplementation significantly increased ERI (p < 0.05), but no significant change was observed (p = 0.931) in HRI. Although zinc supplementation did not significantly affect HRI, adequate zinc supplementation is required to alleviate concerns such as vascular calcification and increased serum copper during the use of HIF-PHI.

Supplementation of red palm olein-enriched biscuits improves levels of provitamin A carotenes, iron, and erythropoiesis in vitamin A-deficient primary schoolchildren: a double-blinded randomised controlled trial.

PURPOSE: Vitamin A deficiency (VAD) remains a significant contributor to childhood morbidity and mortality in developing countries; therefore, the implementation of sustainable and cost-effective approaches to control VAD is of utmost pertinence. This study aims to investigate the efficacy of red palm olein (RPO)-enriched biscuit supplementation in improving vitamin A, haematological, iron, and inflammatory status among vitamin A-deficient schoolchildren. METHODS: We conducted a double-blinded, randomised controlled trial involving 651 rural primary schoolchildren (8-12 years) with VAD in Malaysia. The schoolchildren were randomised to receive either RPO-enriched biscuits (experimental group, n = 334) or palm olein-enriched biscuits (control group, n = 317) for 6-month duration. RESULTS: Significant improvements in retinol and retinol-binding protein 4 levels were observed in both groups after supplementation (P < 0.001). The improvement in retinol levels were similar across groups among subjects with confirmed VAD (P = 0.40). Among those with marginal VAD, greater improvement in retinol levels was recorded in the control group (P < 0.001) but lacked clinical significance. The levels of α- and ß-carotenes, haematological parameters (haemoglobin, packed cell volume, mean corpuscular volume and mean corpuscular haemoglobin) and iron enhanced more significantly in the experimental group (P < 0.05). The significant reduction in the prevalence of microcytic anaemia (- 21.8%) and high inflammation (- 8.1%) was only observed in the experimental group. CONCLUSION: The supplementation of RPO-enriched biscuits enhanced levels of provitamin A carotenes, iron, and erythropoiesis, and exhibited anti-inflammatory effects. Therefore, the incorporation of RPO into National Nutritional Intervention Programs may be a potential measure to improve the health status of vitamin A-deficient children, among various other interventions. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT03256123).

Αlpha-thalassemia: A practical overview.

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and ß globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Unmet needs in ß-thalassemia and the evolving treatment landscape.

ß-thalassemias are genetic disorders causing an imbalance in hemoglobin production, leading to varying degrees of anemia, with two clinical phenotypes: transfusion-dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT). Red blood cell transfusions and iron chelation therapy are the conventional treatment options for the management of ß-thalassemia. Currently available conventional therapies in thalassemia have many challenges and limitations. Accordingly, multiple novel therapeutic approaches are currently being developed for the treatment of ß-thalassemias. These strategies can be classified into three categories based on their efforts to address different aspects of the underlying pathophysiology of ß-thalassemia: correction of the α/ß globin chain imbalance, addressing ineffective erythropoiesis, and targeting iron dysregulation. Managing ß- thalassemia presents challenges due to the many complications that can manifest, limited access and availability of blood products, and lack of compliance/adherence to treatment. Novel therapies targeting ineffective erythropoiesis and thus improving anemia and reducing the need for chronic blood transfusions seem promising. However, the complex nature of the disease itself requires personalized treatment plans for each patient. Collaborations and partnerships between thalassemia centers can also help share knowledge and resources, particularly in regions with higher prevalence and limited resources. This review will explore the different conventional treatment modalities available today for the management of ß-thalassemia, discuss the unmet needs and challenges associated with them in addition to exploring the role of some novel therapeutic agents in the field.

Thalassemia and Nanotheragnostics: Advanced Approaches for Diagnosis and Treatment.

Thalassemia is a monogenic autosomal recessive disorder caused by mutations, which lead to abnormal or reduced production of hemoglobin. Ineffective erythropoiesis, hemolysis, hepcidin suppression, and iron overload are common manifestations that vary according to genotypes and dictate, which diagnosis and therapeutic modalities, including transfusion therapy, iron chelation therapy, HbF induction, gene therapy, and editing, are performed. These conventional therapeutic methods have proven to be effective, yet have several disadvantages, specifically iron toxicity, associated with them; therefore, there are demands for advanced therapeutic methods. Nanotechnology-based applications, such as the use of nanoparticles and nanomedicines for theragnostic purposes have emerged that are simple, convenient, and cost-effective methods. The therapeutic potential of various nanoparticles has been explored by developing artificial hemoglobin, nano-based iron chelating agents, and nanocarriers for globin gene editing by CRISPR/Cas9. Au, Ag, carbon, graphene, silicon, porous nanoparticles, dendrimers, hydrogels, quantum dots, etc., have been used in electrochemical biosensors development for diagnosis of thalassemia, quantification of hemoglobin in these patients, and analysis of conventional iron chelating agents. This review summarizes the potential of nanotechnology in the development of various theragnostic approaches to determine thalassemia-causing gene mutations using various nano-based biosensors along with the employment of efficacious nano-based therapeutic procedures, in contrast to conventional therapies.

Normal range and predictors of serum erythroferrone in infants.

BACKGROUND: Erythroferrone (ERFE) has been identified as a hepcidin-regulating hormone synthetized by erythroblasts correlating to the erythropoietic activity and the needs for iron substrate in bone marrow of adults. The present study aimed to assess the ERFE serum concentrations and its predictors in infants. METHODS: ERFE was explored at 4 time points during the first year of life in 45 healthy, breastfed, normal birth weight (NBW) infants, and 136 marginally low birth weight infants (LBW, 2000-2500 g) receiving iron (N = 58) or placebo (N = 78) between 6 weeks and 6 months of age. RESULTS: ERFE concentrations were low at birth, increasing gradually during the first year of life. In NBW infants, reference ranges (5th to 95th percentile) were at 6 weeks <0.005-0.99 ng/mL and at 12 months <0.005-33.7 ng/mL. ERFE was higher in LBW infants at 6 weeks but lower at 12 months compared to NBW and minimally affected by iron supplementation among LBW infants. Correlations of ERFE with erythropoietic and iron status markers were weak and inconsistent. CONCLUSIONS: The role of ERFE in the crosstalk of erythropoiesis and iron homeostasis remains unclear in infants and further studies on ERFE in infants and older children are warranted within the framework of the erythropoietin-ERFE-hepcidin axis. IMPACT: Normal range of erythroferrone in healthy infants is described for the first time. Erythroferrone in infants lacks correlation to iron status and markers of erythropoiesis. The findings indicate differences in infant regulation of iron homeostasis as compared to adults. The findings point to a need to study infant erythropoiesis separately from its adult counterpart. The findings may have clinical impact on management strategies of iron-loading anemia in infancy.

Gene editing for sickle cell disease and transfusion dependent thalassemias- A cure within reach.

Sickle cell disease (SCD) is associated with significant morbidity and shortened life expectancy. Similarly, patients with transfusion dependent beta thalassemia (TdT) require life-long transfusion therapy, chelation therapy and significant organ dysfunction. Allogeneic transplantation from a matched family donor provided the only curative option for patients with SCD and TdT. Unfortunately, less than 20% of patients have a fully matched related donor and results using unrelated donor transplant were associated with high rate of complications. Ex vivo gene therapy through globin gene addition has been investigated extensively and recent encouraging preliminary data resulted in regulatory approval in patients with TdT. Recent improvements in our understanding of the molecular pathways controlling erythropoiesis and globin switching from fetal hemoglobin to adult hemoglobin offer a new and exciting therapeutic options. Rapid and substantial advances in genome editing tools using CRISPR/Cas9, have raised the possibility of genetic editing and correction in patient derived hematopoietic stem and progenitor cells. We will review results of gene editing approach that can induce fetal hemoglobin production in patients with SCD and TdT.

Vitamin B5 and succinyl-CoA improve ineffective erythropoiesis in SF3B1-mutated myelodysplasia.

Patients with myelodysplastic syndrome and ring sideroblasts (MDS-RS) present with symptomatic anemia due to ineffective erythropoiesis that impedes their quality of life and increases morbidity. More than 80% of patients with MDS-RS harbor splicing factor 3B subunit 1 (SF3B1) mutations, the founder aberration driving MDS-RS disease. Here, we report how mis-splicing of coenzyme A synthase (COASY), induced by mutations in SF3B1, affects heme biosynthesis and erythropoiesis. Our data revealed that COASY was up-regulated during normal erythroid differentiation, and its silencing prevented the formation of erythroid colonies, impeded erythroid differentiation, and precluded heme accumulation. In patients with MDS-RS, loss of protein due to COASY mis-splicing led to depletion of both CoA and succinyl-CoA. Supplementation with COASY substrate (vitamin B5) rescued CoA and succinyl-CoA concentrations in SF3B1mut cells and mended erythropoiesis differentiation defects in MDS-RS primary patient cells. Our findings reveal a key role of the COASY pathway in erythroid maturation and identify upstream and downstream metabolites of COASY as a potential treatment for anemia in patients with MDS-RS.

Changes of biomarkers for erythropoiesis, iron metabolism, and FGF23 by supplementation with roxadustat in patients on hemodialysis.

This study aimed to confirm changes in biomarkers of erythropoiesis and iron metabolism and serum fibroblast growth factor 23 (FGF-23) during darbepoetin-α treatment and then switching to the hypoxia-inducible factor prolyl hydroxylase inhibitor roxadustat. A total of 28 patients on hemodialysis who received weekly doses of darbepoetin-α were switched to roxadustat. Biomarkers for erythropoiesis and iron metabolism and intact and C-terminal FGF-23 were measured in blood samples collected before the HD session on days - 7 (darbepoetin-α injection), - 4, and - 2, and days 0 (switch to roxadustat treatment, three times weekly), 3, 5, 7, 14, 21, and 28. Erythropoietin and erythroferrone levels were elevated on day - 4 by darbepoetin-α injection and decreased to baseline levels at day 0. Levels of erythropoietin were not significantly increased by roxadustat supplementation, but erythroferrone levels were continuously elevated, similar to darbepoetin-α treatment. Hepcidin-25 and total iron binding capacity were significantly decreased or increased in patients treated with roxadustat compared with darbepoetin-α. Changes of intact and C-terminal FGF-23 levels were parallel to changes of phosphate levels during roxadustat treatment. However, the actual and percentage changes of intact FGF-23 and C-terminal FGF-23 in patients with low ferritin levels were greater than those in patients with high ferritin levels. Roxadustat might stimulate erythropoiesis by increasing iron usage through hepcidin-25, which was suppressed by erythroferrone in the physiological erythropoietin condition. Changes of intact FGF-23 and C-terminal FGF-23 levels might be affected by roxadustat in patients on hemodialysis, especially those with a low-iron condition.

The effect of high-dose vitamin D supplementation on hepcidin-25 and erythropoiesis in patients with chronic kidney disease.

BACKGROUND: Hepcidin is considered to play a central role in the pathophysiology of renal anemia. Recent studies in healthy individuals have demonstrated a suppressive effect of vitamin D (VD) on the expression of hepcidin. In this post-hoc analysis based on a randomized controlled study, we evaluated the effect of supplementing chronic kidney disease (CKD) patients (stage G3-G4) with a high daily dose of native VD on serum levels of hepcidin-25, the hepcidin/ferritin ratio, as well as on markers of erythropoiesis. METHODS: Patients with CKD stage G3-G4 included in a double blind, randomized, placebo (PBO) controlled study with available hepcidin measurements were analyzed. Study subjects received either 8000 international units (IU) of cholecalciferol daily or PBO for 12 weeks. We evaluated the change in markers of hepcidin expression, erythropoiesis, and iron status from baseline to week 12 and compared the change between the groups. RESULTS: Eighty five patients completed the study. Calcitriol, but not 25-hydroxyvitamin D (25(OH) D), was inversely correlated with serum levels of hepcidin-25 (rho = -0,38; p = < 0, 01 and rho = -0,02; p = 0, 89, respectively) at baseline. Supplementation with VD significantly raised the serum concentration of serum 25(OH)D in the treatment group (from 54 (39-71) to 156 (120-190) nmol/L; p = < 0, 01)) but had no effect on any of the markers of hepcidin, erythropoiesis, or iron status in the entire cohort. However, we did observe an increase in hemoglobin (HB) levels and transferrin saturation (TSAT) as compared to the PBO group in a subgroup of patients with low baseline 25(OH)D levels (< 56 nmol/L). In contrast, in patients with high baseline 25(OH)D values (≥ 56 nmol/L), VD supplementation associated with a decrease in HB levels and TSAT (p = 0,056) within the VD group in addition to a decrease in hepcidin levels as compared to the PBO group. CONCLUSION: High-dose VD supplementation had no discernible effect on markers of hepcidin or erythropoiesis in the entire study cohort. However, in patients with low baseline 25(OH)D levels, high-dose VD supplementation associated with beneficial effects on erythropoiesis and iron availability. In contrast, in patients with elevated baseline 25(OH)D levels, high-dose VD supplementation resulted in a decrease in hepcidin levels, most likely due to a deterioration in iron status.

Hyporesponsiveness to erythropoiesis-stimulating agent in non-dialysis-dependent CKD patients: The BRIGHTEN study.

Among non-dialysis-dependent chronic kidney disease (ND-CKD) patients, a low hematopoietic response to erythropoiesis-stimulating agents (ESAs) is a predictor for poor renal and cardiovascular outcome. To assess the method for evaluating hyporesponsiveness to ESA in patients with ND-CKD, a multicenter, prospective, observational study of 1,980 adult patients with ND-CKD with renal anemia was conducted. Darbepoetin alfa (DA) and iron supplement administrations were provided according to the recommendation of the attached document and the guidelines of JSDT (Japanese Society of Dialysis and Transplantation). The primary outcomes were progression of renal dysfunction and major adverse cardiovascular events. ESA responsiveness was assessed using pre-defined candidate formulae. During the mean follow-up period of 96 weeks, renal and cardiovascular disease (CVD) events occurred in 683 (39.6%) and 174 (10.1%) of 1,724 patients, respectively. Among pre-set candidate formulae, the one expressed by dividing the dose of DA by Hb level at the 12-week DA treatment was statistically significant in predicting renal (hazard ratio [HR], 1.449; 95% confidence interval [CI], 1.231-1.705; P<0.0001) and CVD events (HR, 1.719; 95% CI, 1.239-2.386; P = 0.0010). The optimum cut-off values for both events were close to 5.2. In conclusion, hyporesponsiveness to ESA in ND-CKD cases, which is associated with a risk for renal and CVD events, may be evaluated practicably as the dose of DA divided by the Hb level at the 12-week DA treatment, and the cut-off value of this index is 5.2. A search for the causes of poor response and measures for them should be recommended in such patients. Trial registration: ClinicalTrials. gov Identifier: NCT02136563; UMIN Clinical Trial Registry Identifier: UMIN000013464.

Adverse events of iron and/or erythropoiesis-stimulating agent therapy in preoperatively anemic elective surgery patients: a systematic review.

BACKGROUND: Iron supplementation and erythropoiesis-stimulating agent (ESA) administration represent the hallmark therapies in preoperative anemia treatment, as reflected in a set of evidence-based treatment recommendations made during the 2018 International Consensus Conference on Patient Blood Management. However, little is known about the safety of these therapies. This systematic review investigated the occurrence of adverse events (AEs) during or after treatment with iron and/or ESAs. METHODS: Five databases (The Cochrane Library, MEDLINE, Embase, Transfusion Evidence Library, Web of Science) and two trial registries (ClinicalTrials.gov, WHO ICTRP) were searched until 23 May 2022. Randomized controlled trials (RCTs), cohort, and case-control studies investigating any AE during or after iron and/or ESA administration in adult elective surgery patients with preoperative anemia were eligible for inclusion and judged using the Cochrane Risk of Bias tools. The GRADE approach was used to assess the overall certainty of evidence. RESULTS: Data from 26 RCTs and 16 cohort studies involving a total of 6062 patients were extracted, on 6 treatment comparisons: (1) intravenous (IV) versus oral iron, (2) IV iron versus usual care/no iron, (3) IV ferric carboxymaltose versus IV iron sucrose, (4) ESA+iron versus control (placebo and/or iron, no treatment), (5) ESA+IV iron versus ESA+oral iron, and (6) ESA+IV iron versus ESA+IV iron (different ESA dosing regimens). Most AE data concerned mortality/survival (n=24 studies), thromboembolic (n=22), infectious (n=20), cardiovascular (n=19) and gastrointestinal (n=14) AEs. Very low certainty evidence was assigned to all but one outcome category. This uncertainty results from both the low quantity and quality of AE data due to the high risk of bias caused by limitations in the study design, data collection, and reporting. CONCLUSIONS: It remains unclear if ESA and/or iron therapy is associated with AEs in preoperatively anemic elective surgery patients. Future trial investigators should pay more attention to the systematic collection, measurement, documentation, and reporting of AE data.

Regulators impeding erythropoiesis following iron supplementation in a clinically relevant rat model of iron deficiency anemia with inflammation.

AIMS: While elevated hepcidin levels with inflammation have been postulated as a putative mechanism hindering effective erythropoiesis after intravenous (IV) iron therapy in anemic patients undergoing surgery, little is known about the concomitant changes in other major regulators affecting erythropoiesis. This study investigated the activities of relevant regulators after iron replenishment in a rat model of iron deficiency anemia with inflammation. MAIN METHODS: Inflammation was induced by administration of complete Freund's adjuvant (CFA) in male Sprague-Dawley rats. After 2 weeks of CFA treatment, the rats received IV iron (CFA­iron) or saline (CFA-saline). The control group received saline instead of CFA and iron (saline-saline). At 1, 3, and 10 days after iron or saline treatment, inflammatory cytokines, oxidative markers, iron profiles, hepcidin, erythropoietin (EPO), erythroferrone (ERFE), fibroblast growth factor 23 (FGF 23), and expression of mRNA and proteins in the liver involved in hepcidin signaling pathways were measured. KEY FINDINGS: CFA treatment and iron restriction decreased hemoglobin and serum iron levels, significantly increasing inflammatory and oxidative markers. Iron supplementation did not restore hemoglobin levels despite improved iron profiles. CFA injections increased hepcidin and FGF 23 levels and decreased EPO and ERFE levels, which further intensified after iron supplementation with concomitantly elevated levels of oxidative stress and inflammatory markers. SIGNIFICANCE: Under inflammatory conditions, IV iron administration exacerbated inflammatory and oxidative stress and did not resolve anemia, even under iron deficiency conditions. Iron therapy exerted adverse influences on the changes in key regulators toward impeding erythropoiesis that was already impeded by inflammation.

Parathyroidectomy Improves the Consumption of Erythropoiesis-Stimulating Agents in Hemodialysis Patients.

Secondary hyperparathyroidism (SHPT) is common in end-stage renal disease (ESRD) patients, and it can suppress erythropoiesis. We aimed to investigate the relationship between the consumption of erythropoiesis-stimulating agents (ESAs) and parathyroidectomy (PTX) in ESRD patients with SHPT and to determine the predictors for anemia improvement. The current standard of chronic kidney disease anemia therapy relies on the prescription of iron supplementation, and ESA. We retrospectively analyzed 81 ESRD patients with PTX at Ditmanson Medical Foundation Chiayi Christian Hospital from July 2004 to Dec 2018. The requirement of ESA therapy markedly declined from a dose of 41.6 (interquartile range [IQR], 0−91.2) to 10.3 (IQR, 0−59.5, p = 0.001) unit/kg/week. In addition, 63.7% of patients required iron replacement therapy preoperatively and the proportion reduced to 52.5% after PTX (p < 0.001). The hemoglobin (Hb) level showed an insignificant change from a median value of 10.7 g/dL (9.5−11.6 g/dL) before PTX to 10.5 g/dL (9.6−11.2 g/dL) at 6 months after PTX. A preoperative Hb level ≤ 10 mg/dL (odds ratio [OR], 20.1; 95% confidence interval [CI], 4.71−125, p < 0.001) and transferrin saturation (TSAT) < 25% (OR, 12.8; 95% CI, 2.51−129, p < 0.001) were predictors for anemia improvement. Our study demonstrated that PTX markedly decreased the requirement of ESA. Patients with a low preoperative Hb level or low TSAT showed an increase in the Hb level after PTX. PTX may be considered not only for SHPT with refractory anemia but also for high ESA-dependent patients.

Differential Impact of SARS-CoV-2 Isolates, Namely, the Wuhan Strain, Delta, and Omicron Variants on Erythropoiesis.

SARS-CoV-2 variants exhibit different viral transmissibility and disease severity. However, their impact on erythropoiesis has not been investigated. Here, we show SARS-CoV-2 variants differentially affect erythropoiesis. This is illustrated by the abundance of CD71+ erythroid cells (CECs) in the blood circulation of COVID-19 patients infected with the original Wuhan strain followed by the Delta and Omicron variants. We observed the CD45+CECs are the dominant subpopulation of CECs expressing the receptor, ACE2, and coreceptor, TMPRSS2, and thus, can be targeted by SARS-CoV-2. Also, we found CECs exhibit immunosuppressive properties, specifically CD45+CECs are the dominant immunosuppressive cells and via reactive oxygen species (ROS) and arginase I expression can impair CD8+ T cell functions. In agreement, we observed CECs suppress CD8+ T cell effector (e.g., Granzyme B expression and degranulation capacity [CD107]), which was partially but significantly reversed with l-arginine supplementation. In light of the enriched frequency of CECs, in particular, CD45+CECs in patients infected with the original (Wuhan) strain, we believe this strain has a more prominent impact on hematopoiesis compared with the Delta and Omicron variants. Therefore, our study provides an important insight into the differential impact of SARS-CoV-2 variants on erythropoiesis in COVID-19 patients. IMPORTANCE Silent hypoxia has been the hallmark of SARS-CoV-2 infection. Red blood cells (RBCs) work as gas cargo delivering oxygen to different tissues. However, their immature counterparts reside in the bone marrow and normally absent in the blood circulation. We show SARS-CoV-2 infection is associated with the emergence of immature RBCs so called CD71+ erythroid cells (CECs) in the blood. In particular, we found these cells were more prevalent in the blood of those infected with the SARS-CoV-2 original strain (Wuhan) followed by the Delta and Omicron variants. This suggests SARS-CoV-2 directly or indirectly impacts RBC production. In agreement, we observed immature RBCs express the receptor (ACE2) and coreceptor (TMPRSS2) for SARS-CoV-2. CECs suppress T cells functions (e.g., Granzyme B and degranulation capacity) in vitro. Therefore, our study provides a novel insight into the differential impact of SARS-CoV-2 variants on erythropoiesis and subsequently the hypoxia commonly observed in COVID-19 patients.

Future perspectives of anemia management in chronic kidney disease using hypoxia-inducible factor-prolyl hydroxylase inhibitors.

For the past 3 decades, erythropoiesis-stimulating agents (ESA) in conjunction with iron supplementation has been the mainstay of treatment for anemia in chronic kidney disease (CKD). Although ESAs are well-established and highly efficacious treatment, clinical trials demonstrated that the use of ESAs with a high hemoglobin (Hb) target was associated with increased risk of cardiovascular events. This safety concern raised considerable interest in developing an alternative therapeutic strategy. Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) are such novel agents to treat anemia in CKD. They stimulate endogenous erythropoietin production via HIF activation and thereby induce erythropoiesis. At least 6 small-molecule HIF-PHIs have been developed to date. The phase 3 clinical trials demonstrated that their effects were noninferior to ESAs. HIF-PHIs may have several advantages over the conventional treatment, such as oral route of administration and their ability to raise Hb levels in patients with chronic inflammation. Although many of the phase 3 clinical trials demonstrated that HIF-PHIs were noninferior to placebo or ESAs with respect to cardiovascular safety, one of the compounds failed to meet the prespecified noninferiority criterion in non-dialysis-dependent CKD patients, and some studies of another HIF-PHI indicated potential risks for thromboembolic events. While the regulatory agencies of some countries including Japan and the European Union concluded that roxadustat, one of the HIF-PHIs, had a favorable benefit-risk profile, the U.S. Food and Drug Administration decided not to approve the drug because of safety reasons. In order to establish the optimal anemia management in CKD, further studies are needed to evaluate important aspects of HIF-PHIs, such as long-term safety, appropriate Hb target, and the types of patients who would gain benefits from these new drugs.

The addition of oral iron improves chemotherapy-induced anemia in patients receiving erythropoiesis-stimulating agents.

Although many studies have shown that supplementation with iron and erythropoiesis-stimulating agents (ESA) is frequently used for managing chemotherapy-induced anemia (CIA), optimal combination therapy using these agents together to ameliorate anemia is not well characterized. To assess the effects of ESA combined with oral or intravenous (IV) iron on relieving CIA, PubMed, Cochrane Library, Embase and China National Knowledge Infrastructure (CNKI) were searched for articles. Data collected in the articles were meta-analyzed using RevMan 5.3 software with a random-effects model. Our comprehensive search yielded 1666 potentially relevant trials. A total of 41 trials randomizing 4200 patients with CIA fulfilled inclusion criteria, including 34 Chinese articles and 7 English articles. Meta-analysis showed that treatment with both ESA and iron more effectively improved CIA relative to iron supplementation alone, with increased hemoglobin, hematocrit, red blood cell count and hematopoietic response rate. Subgroup analyses revealed iron administration, both oral and IV iron, improved anemia in ESA-treated cancer patients with CIA. Our analysis demonstrates that iron supplementation combined with ESA more effectively ameliorates CIA relative to iron supplementation alone, without regard to whether IV or oral iron was used. Together, our findings may contribute to the clinical treatment of CIA using iron therapy with or without ESA.

Role of Zinc and Copper in Erythropoiesis in Patients on Hemodialysis.

Plasma zinc concentrations are decreased in patients on hemodialysis; zinc supplementation increases hemoglobin levels and reduces erythropoietin-stimulating agent treatments. However, inappropriate zinc supplementation causes copper deficiency. This review discusses the roles of zinc and copper throughout erythropoiesis; it also describes erythropoiesis-stimulating nutritional therapy that avoids copper deficiency, while providing safe zinc supplementation. In early erythropoiesis, erythropoietin regulates erythrocyte precursor proliferation and survival via zinc finger transcription factors. Mature blood cell formation and functional activation are regulated by zinc-mediated hormones, vitamins, and growth peptides. Zinc antagonizes the uptake of divalent cations (e.g., iron and copper) in erythrocyte precursors. Copper is required for iron transfer from cells to blood, ensuring dietary iron absorption and systemic iron distribution. In patients with copper deficiency, copper supplementation is initially performed, followed by zinc supplementation to manage hypozincemia. Serum zinc and copper measurements are needed at 2- to 3-month intervals during zinc supplementation to prevent copper deficiency.

Heme-stress activated NRF2 skews fate trajectories of bone marrow cells from dendritic cells towards red pulp-like macrophages in hemolytic anemia.

Heme is an erythrocyte-derived toxin that drives disease progression in hemolytic anemias, such as sickle cell disease. During hemolysis, specialized bone marrow-derived macrophages with a high heme-metabolism capacity orchestrate disease adaptation by removing damaged erythrocytes and heme-protein complexes from the blood and supporting iron recycling for erythropoiesis. Since chronic heme-stress is noxious for macrophages, erythrophagocytes in the spleen are continuously replenished from bone marrow-derived progenitors. Here, we hypothesized that adaptation to heme stress progressively shifts differentiation trajectories of bone marrow progenitors to expand the capacity of heme-handling monocyte-derived macrophages at the expense of the homeostatic generation of dendritic cells, which emerge from shared myeloid precursors. This heme-induced redirection of differentiation trajectories may contribute to hemolysis-induced secondary immunodeficiency. We performed single-cell RNA-sequencing with directional RNA velocity analysis of GM-CSF-supplemented mouse bone marrow cultures to assess myeloid differentiation under heme stress. We found that heme-activated NRF2 signaling shifted the differentiation of bone marrow cells towards antioxidant, iron-recycling macrophages, suppressing the generation of dendritic cells in heme-exposed bone marrow cultures. Heme eliminated the capacity of GM-CSF-supplemented bone marrow cultures to activate antigen-specific CD4 T cells. The generation of functionally competent dendritic cells was restored by NRF2 loss. The heme-induced phenotype of macrophage expansion with concurrent dendritic cell depletion was reproduced in hemolytic mice with sickle cell disease and spherocytosis and associated with reduced dendritic cell functions in the spleen. Our data provide a novel mechanistic underpinning of hemolytic stress as a driver of hyposplenism-related secondary immunodeficiency.