Molecular mechanisms of hepcidin regulation: implications for the anemia of CKD

Iron Metabolism and Inflammatory Mediators in Patients with Renal Dysfunction

Chronic kidney disease (CKD) affects around 850 million people worldwide, posing significant challenges in healthcare due to complications like renal anemia, end-stage kidney disease, and cardiovascular diseases. This review focuses on the intricate interplay between iron metabolism, inflammation, and renal dysfunction in CKD. Renal anemia, prevalent in CKD, arises primarily from diminished erythropoietin (EPO) production and iron dysregulation, which worsens with disease progression. Functional and absolute iron deficiencies due to impaired absorption and chronic inflammation are key factors exacerbating erythropoiesis. A notable aspect of CKD is the accumulation of uremic toxins, such as indoxyl sulfate (IS), which hinder iron metabolism and worsen anemia. These toxins directly affect renal EPO synthesis and contribute to renal hypoxia, thus playing a critical role in the pathophysiology of renal anemia. Inflammatory cytokines, especially TNF-α and IL-6, further exacerbate CKD progression and disrupt iron homeostasis, thereby influencing anemia severity. Treatment approaches have evolved to address both iron and EPO deficiencies, with emerging therapies targeting hepcidin and employing hypoxia-inducible factor (HIF) stabilizers showing potential. This review underscores the importance of integrated treatment strategies in CKD, focusing on the complex relationship between iron metabolism, inflammation, and renal dysfunction to improve patient outcomes.

Gut microbial metabolites SCFAs and chronic kidney disease

The global incidence of Chronic Kidney Disease (CKD) is steadily escalating, with discernible linkage to the intricate terrain of intestinal microecology. The intestinal microbiota orchestrates a dynamic equilibrium in the organism, metabolizing dietary-derived compounds, a process which profoundly impacts human health. Among these compounds, short-chain fatty acids (SCFAs), which result from microbial metabolic processes, play a versatile role in influencing host energy homeostasis, immune function, and intermicrobial signaling, etc. SCFAs emerge as pivotal risk factors influencing CKD's development and prognosis. This paper review elucidates the impact of gut microbial metabolites, specifically SCFAs, on CKD, highlighting their role in modulating host inflammatory responses, oxidative stress, cellular autophagy, the immune milieu, and signaling cascades. An in-depth comprehension of the interplay between SCFAs and kidney disease pathogenesis may pave the way for their utilization as biomarkers for CKD progression and prognosis or as novel adjunctive therapeutic strategies.

Hemodiafiltration with endogenous reinfusion of the regenerated ultrafiltrate (HFR): towards a convective, diffusive, and adsorptive dialysis

Hemodiafiltration with endogenous reinfusion of the ultrafiltrate (HFR) is a dialysis technique characterized by a resin cartridge with adsorptive properties that combines the mechanisms of diffusion, convection, and adsorption in a single therapeutic regimen. After nearly 20 years of clinical experience with HFR, this article reviews the accumulated evidence with this technique, considering whether adsorption reduction, as a third purification mechanism, should be the next step in the treatment of hemodialysis patients. HFR, beyond producing an extensive removal of uremic toxins, has demonstrated to reduce the loss of nutrients and other physiological components during the dialysis session as compared to online hemodiafiltration, ameliorating the inflammatory state and oxidative stress in this population. In addition to its ease of use, the technique is also highly biocompatible and can be used in patients with a compromised vascular access. Based on these observations, HFR appears to be an especially useful therapy for high-comorbidity patients, including those with frailty, malnutrition, or cardiovascular disease. In this review, we, as a consensus panel of nephrologists experienced with HFR, survey existing literature and summarize our views on when to use this technique, which patients may be best suited for HFR, and how to effectively prescribe and monitor this modality of dialysis in daily clinical practice.

The first study on urinary loss of iron and transferrin in association with proteinuria in dogs with chronic kidney disease

Background and Aim

Anemia is an important factor in surviving chronic kidney disease (CKD). Anemia in CKD is associated with various factors, such as inadequate production of erythropoietin and the availability of iron and its binding protein. Reduced total iron-binding capacity (TIBC) and iron concentrations may be related to their urinary loss along with proteinuria. This study aimed to determine the urinary loss of iron and transferrin (TF) in relation to the degree of proteinuria.

Materials and Methods

The study was performed on 37 dogs with CKD. Dogs were divided according to the severity of proteinuria into two groups based on the mean of urinary protein-creatinine (UPC) ratio into UPC ratio <4 and UPC ratio >4. The hematocrit (HCT), blood chemistries, plasma iron, plasma TF, UPC ratio, urinary iron per creatinine ratio (U-Iron/CR), and urinary TF per creatinine ratio (U-TF/CR) were evaluated.

Results

Anemia was associated with the severity of renal impairment as demonstrated by reduction of HCT when staging of CKD was higher. Dogs with UPC ratio >4 had higher urinary loss of both U-Iron/CR (p < 0.01) and U-TF/CR (p < 0.001) with lower plasma TIBC (p < 0.001). The UPC ratio was positively correlated with both U-Iron/CR (r = 0.710, p < 0.001) and U-TF/CR (r = 0.730, p < 0.001) but negatively with TIBC (r = -0.462, p < 0.01).

Conclusion

Proteinuria was associated with urinary loss of both iron and TF which may contribute to anemia in CKD.

Updates on Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors in the Treatment of Renal Anemia

Background

Anemia is a common complication of chronic kidney disease. The hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) is a new class of oral drugs for the treatment of renal anemia.

Summary

Clinical trials have consistently shown that HIF-PHIs can effectively increase hemoglobin in both the dialysis population and the nondialysis population. The effects of HIF-PHIs in treating renal anemia include promoting endogenous erythropoietin production and facilitating iron mobilization. Several studies suggest that the erythropoiesis effect of roxadustat is less affected by inflammation. Careful monitoring of thromboembolic events and tumor before and during HIF-PHI treatment is necessary.

Key Messages

HIF-PHIs are effective in correcting renal anemia. The long-term safety of HIF-PHIs needs to be further studied.

[Management of iron deficiency in chronic kidney disease: Review and proposed algorithm]

Iron deficiency is very common in chronic kidney disease, even before the dialysis stage. It is an independent factor of morbidity and mortality in patients with non-dialysis chronic kidney disease. During chronic kidney disease, iron deficiency is defined by a transferrin saturation <20% and/or a serum ferritin <100 μg/L. In France, about half of non-dialysis chronic kidney disease patients have absolute iron deficiency (transferrin saturation <20% and serum ferritin <100 μg/L) and/or functional iron deficiency (transferrin saturation <20% and serum ferritin >100 μg/L). Despite this, iron deficiency is usually not investigated. In fact, more than 60% of nephrologists do not assess iron status at least once a year. In addition, iron deficiency is rarely treated: only 12% of patients are prescribed oral or intravenous iron. Early detection and treatment are fundamental and should be systematic. In order to help improve the management of iron deficiency among non-dialysis chronic kidney disease patients, we propose an algorithm that takes into account current recommendations and the most recent data from the literature. Initial blood test requires the measurement of hemoglobin concentration, transferrin saturation and serum ferritin. A transferrin saturation <20% establishes the diagnosis of iron deficiency and the serum ferritin level points towards an absolute or functional deficiency. The combination of both values makes it possible to adapt the treatment, particularly in an inflammatory context where oral iron is not effective.

Treatment of Renal Anemia in Patients With Hemodialysis Using Hypoxia-inducible Factor (HIF) Stabilizer, Roxadustat: A Short-term Clinical Study

BACKGROUND/AIM

Renal anemia is a major complication in patients with chronic kidney disease (CKD) and hemodialysis, increasing morbidity and mortality. Roxadustat is a novel oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor (PHI), which is administrated for renal anemia. Different from erythropoiesis-stimulating agents (ESAs), Roxadustat could increase erythropoietin physiologically, improving the therapeutic effects. It has not been so long since Roxadustat was approved by the European Commission (EC). Thus, only a few studies have reported on the treatment of renal anemia using Roxadustat.

PATIENTS AND METHODS

In this study, we evaluated the efficacy of Roxadustat in patients undergoing hemodialysis (HD). Nine patients under HD (72±10 years old) were enrolled in this study. Patients received Roxadustat first time or changed from ESAs (5-10 mg, 3 times a week after HD). Observation period was 5.3±2.9 months.

RESULTS

Roxadustat treatment effectively increased and maintained hemoglobin levels. Levels of ferritin and C-reactive protein tended to decrease, but the difference was not statistically significant. No significant adverse effects were observed in all patients during the study.

CONCLUSION

Roxadustat is effective and relatively tolerant for treating renal anemia in patients subjected to hemodialysis.

Segregating the effects of ferric citrate-mediated iron utilization and FGF23 in a mouse model of CKD

Ferric citrate (FC) is an approved therapy for chronic kidney disease (CKD) patients as a phosphate (Pi) binder for dialysis-dependent CKD, and for iron deficiency anemia (IDA) in non-dialysis CKD. Elevated Pi and IDA both lead to increased FGF23, however, the roles of iron and FGF23 during CKD remain unclear. To this end, iron and Pi metabolism were tested in a mouse model of CKD (0.2% adenine) ± 0.5% FC for 6 weeks, with and without osteocyte deletion of Fgf23 (flox-Fgf23/Dmp1-Cre). Intact FGF23 (iFGF23) increased in all CKD mice but was lower in Cre+ mice with or without FC, thus the Dmp1-Cre effectively reduced FGF23. Cre+ mice fed AD-only had higher serum Pi than Cre- pre- and post-diet, and the Cre+ mice had higher BUN regardless of FC treatment. Total serum iron was higher in all mice receiving FC, and liver Tfrc, Bmp6, and hepcidin mRNAs were increased regardless of genotype; liver IL-6 showed decreased mRNA in FC-fed mice. The renal 1,25-dihydroxyvitamin D (1,25D) anabolic enzyme Cyp27b1 had higher mRNA and the catabolic Cyp24a1 showed lower mRNA in FC-fed mice. Finally, mice with loss of FGF23 had higher bone cortical porosity, whereas Raman spectroscopy showed no changes in matrix mineral parameters. Thus, FC- and FGF23-dependent and -independent actions were identified in CKD; loss of FGF23 was associated with higher serum Pi and BUN, demonstrating that FGF23 was protective of mineral metabolism. In contrast, FC maintained serum iron and corrected inflammation mediators, potentially providing ancillary benefit.

Comparison of Ferric Sodium EDTA in Combination with Vitamin C, Folic Acid, Copper Gluconate, Zinc Gluconate, and Selenomethionine as Therapeutic Option for Chronic Kidney Disease Patients with Improvement in Inflammatory Status

Anemia is one of the most frequent and earliest complications of chronic kidney disease (CKD), which impacts a patient’s quality of life and increases the risk of adverse clinical outcomes. Patients’ inflammatory status is strictly related to the occurrence of functional iron deficiency anemia (IDA) because this causes an increase in hepcidin levels with the consequent inhibition of iron absorption and release from cellular stores into blood circulation. The aim of this study was to evaluate the use of the new oral formulation based on ferric sodium EDTA in combination with vitamin C, folic acid, copper gluconate, zinc gluconate, and selenomethionine (Ferachel Forte®) in patients with moderate CKD and functional IDA, analyzing the inflammatory status in addition to iron blood parameters, in comparison with oral ferrous sulfate and liposomal iron therapies. Sixty-two elderly patients were randomly allocated to one of the following oral treatments for 6 months: ferrous sulfate (Group 1; N = 20), ferric sodium EDTA in combination (Group 2; N = 22), and ferric liposomal formulation (Group 3; N = 20). The evaluated parameters included iron profile parameters of hemoglobin (Hb), sideremia, ferritin, transferrin saturation, C-reactive protein (CRP), and hepcidin. The results showed that in Group 1, there were no improvements. In Group 2, there were statistically significant (p < 0.001) improvements in all evaluated parameters. Finally, in Group 3, there were significant improvements in all evaluated parameters except for hepcidin, which was less than that of Group 2 patients. In conclusion, the findings showed the superior efficacy of the formulation based on ferric sodium EDTA over the other oral iron sources, and that this formulation can contribute to reducing the systemic inflammatory status in patients with CKD.

Evaluation of Predicting the Value of the Reticulocyte Hemoglobin Equivalent for Iron Deficiency in Chronic Kidney Disease Patients

Background: Iron management is essential for anemia treatment in chronic kidney disease. The reticulocyte hemoglobin equivalent (RET-He) is a reticulocyte parameter that reflects hemoglobin synthesis of newly formed erythrocytes in the bone marrow in real-time. Objectives: This study aims to evaluate the role of reticulocyte hemoglobin equivalent (RET-He) in predicting iron deficiency in chronic kidney disease (CKD) patients. Methods: Following a descriptive cross-sectional observational design, this study was conducted on 131 adult patients with CKD stages 3 - 5. Laboratory indices, including complete blood count, some biochemical indices, iron status, and reticulocyte indices (including RET-He), were measured. Iron deficiency (ID) was defined as TSAT < 20%, where serum ferritin level > 100 ng/mL was defined as functional ID, while serum ferritin level

Clinical interpretation of serum hepcidin-25 in inflammation and renal dysfunction

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log[hepcidin]:log[ferritin] ratio may serve as a biomarker for iron deficiency in complex cases.

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Hepcidin testing is not warranted in patients with CRP > 10 mg/l and/or eGFR < 30 ml/min/1.73 m².

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Inflammation is not a determinant of serum hepcidin-25 in the setting of renal dysfunction.

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eGFR is not a major determinant of serum hepcidin-25 concentration in patient with eGFR ≥ 30 ml/min/1.73 m².

Introduction

Hepcidin is a hormone that regulates systemic iron homeostasis. Serum hepcidin levels are under the influence of various stimuli, particularly inflammation and renal dysfunction. The measurement of hepcidin in circulation is a potentially useful clinical tool in the diagnosis, monitoring and treatment of iron metabolism disorder, although clinical interpretation of hepcidin level remains difficult. We evaluated he diagnostic potential and limitations of hepcidin-25 by investigating its relationship with iron and hematological indices, inflammation, and renal dysfunction.

Methods

This retrospective study included 220 adult patients not requiring dialysis. Variations of biologically active hepcidin-25 were examined using a mass spectrometry-based assay in various inflammatory and renal states. The log[hepcidin]:log[ferritin] ratio was calculated as an hepcidin index.

Results

In 220 adult patients not requiring dialysis, variation in hepcidin-25 level was significantly larger once CRP exceeded 10 mg/l (p < 0.001). Inflammation was not a determinant of hepcidin-25 in the setting of renal dysfunction. Hepcidin-25 median (7.37 nM) and variance were significantly higher (p < 0.001), once estimated glomerular filtration rate (eGFR) dropped below 30 ml/min/1.73 m². The log[hepcidin]:log[ferritin] index normalized hepcidin levels. Patients with iron deficiency have a notably lower index when compared to controls (-0.66 vs 0.3).

Conclusion

Severe renal dysfunction (eGFR < 30) affected hepcidin-25 expression and clearance to variable degree between individuals. Although, hepcidin-25 testing is not warranted in patients with infection, inflammatory autoimmune conditions (CRP > 10 mg/l) and/or severe renal dysfunction (eGFR < 30), the hepcidin index may serve as a potential biomarker for iron deficiency in complex cases.

Deficiência de Ferro na Insuficiência Cardíaca com Fração de Ejeção Reduzida: Fisiopatologia, Diagnóstico e Tratamento

A deficiência de ferro (DF) ou ferropenia é uma importante comorbidade na insuficiência cardíaca com fração de ejeção reduzida (ICFER) estável, e muito prevalente tanto nos anêmicos como não anêmicos. A ferropenia na ICFER deve ser pesquisada por meio da coleta de saturação de transferrina e ferritina. Há dois tipos de ferropenia na IC: absoluta, em que as reservas de ferro estão depletadas; e funcional, onde o suprimento de ferro é inadequado apesar das reservas normais. A ferropenia está associada com pior classe funcional e maior risco de morte em pacientes com ICFER, e evidências científicas apontam melhora de sintomas e de qualidade de vida desses pacientes com tratamento com ferro parenteral na forma de carboximaltose férrica. O ferro exerce funções imprescindíveis como o transporte (hemoglobina) e armazenamento (mioglobina) de oxigênio, além de ser fundamental para o funcionamento das mitocôndrias, constituídas de proteínas à base de ferro, e local de geração de energia na cadeia respiratória pelo metabolismo oxidativo. A geração insuficiente e utilização anormal de ferro nas células musculares esquelética e cardíaca contribuem para a fisiopatologia da IC. A presente revisão tem o objetivo de aprofundar o conhecimento a respeito da fisiopatologia da ferropenia na ICFER, abordar as ferramentas disponíveis para o diagnóstico e discutir sobre a evidência científica existente de reposição de ferro.

Efficacy and Safety of Vadadustat for Anemia in Patients With Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Background: Vadadustat is a novel drug for treating anemia patients with chronic kidney disease (CKD), but its effect and safety remain uncertain. This study aimed to summarize the evidence for vadadustat in the treatment of CKD patients with anemia.

Methods: PubMed, Ovid Medline, Embase, Cochrane CENTRAL, Wanfang Data, China National Knowledge Infrastructure and an international trial register were searched from their inception to June 2021 for randomized controlled trials (RCTs) comparing the efficacy and safety of vadadustat to those of placebo or erythropoiesis-stimulating agents (ESAs) in treating anemia in CKD patients. Data were pooled in a meta-analysis, with results expressed as the mean difference for continuous outcomes and relative risk for categorical outcomes with 95% confidence intervals (95% CIs). The certainty of evidence was rated according to Cochrane methods and the GRADE approach.

Results: Ten RCTs comparing vadadustat with placebo (4 RCTs) or darbepoetin alfa (6 RCTs) were included (n = 8,438 participants). Compared with placebo, vadadustat increased the hemoglobin (Hb) response rate (risk ratio 5.27; 95% CI: 2.69 to 10.31; p &lt; 0.001; high certainty of evidence) and Hb level from baseline (∆Hb) (mean difference (MD) 1.28; 95% CI: 0.83 to 1.73; p &lt; 0.001; low certainty of evidence). Compared with placebo or darbepoetin alfa, vadadustat decreased hepcidin (MD -36.62; 95% CI: −54.95 to −18.30; p &lt; 0.001) and ferritin (MD −56.24; 95% CI: −77.37 to −35.11; p &lt; 0.001) levels and increased iron-binding capacity (MD 24.38; 95% CI: 13.69 to 35.07; p &lt; 0.001), with a low to moderate certainty of evidence. Moderate to high certainty evidence suggested that compared with placebo or darbepoetin alfa, vadadustat significantly increased the risk of nausea and diarrhea but did not significantly increase the risk of serious adverse events, especially all-cause mortality, cardiac events and nonfatal stroke.

Conclusion: Vadadustat may safely improve Hb levels and promote iron utilization in CKD patients with anemia without increasing the incidence of serious adverse events.

Predictive role of fluctuating biochemical parameters for mortality in hemodialysis patients

INTRODUCTION

High inflammation parameters like CRP and low albumin levels are considered as risk factors in CKD stage 5 patients. Due to dynamic changes in these parameters, there is evidence of an association between their variation and mortality in hemodialysis patients.

METHODS

We retrospectively analyzed 153 patients on chronic hemodialysis. Dialysis-specific biochemical parameters were measured at three-month intervals over a 42-month period. Fluctuations were calculated as the percentage change in two subsequent measurements.

RESULTS

Median age was 70 years. 41.10% of the patients died over the study period. Higher fluctuation rates in albumin and CRP were significantly associated with a higher mortality rate. Regression analysis revealed that only the fluctuations in albumin proved to be a predictive variable for the end point "death". If the fluctuation in albumin increases by 1%, the mortality risk rises by 22%.

CONCLUSION

Fluctuations in albumin are of predictive importance in patients on chronic hemodialysis.

Blood-incompatibility in haemodialysis: alleviating inflammation and effects of coagulation

Blood-incompatibility is an inevitability of all blood-contacting device applications and therapies, including haemodialysis (HD). Blood leaving the environment of blood vessels and the protection of the endothelium is confronted with several stimuli of the extracorporeal circuit (ECC), triggering the activation of blood cells and various biochemical pathways of plasma. Prevention of blood coagulation, a major obstacle that needed to be overcome to make HD possible, remains an issue to contend with. While anticoagulation (mainly with heparin) successfully prevents clotting within the ECC to allow removal of uraemic toxins across the dialysis membrane wall, it is far from ideal, triggering heparin-induced thrombocytopenia in some instances. Soluble fibrin can form even in the presence of heparin and depending on the constitution of the patient and activation of platelets, could result in physical clots within the ECC (e.g. bubble trap chamber) and, together with other plasma and coagulation proteins, result in increased adsorption of proteins on the membrane surface. The buildup of this secondary membrane layer impairs the transport properties of the membrane to reduce the clearance of uraemic toxins. Activation of complement system-dependent immune response pathways leads to leukopenia, formation of platelet–neutrophil complexes and expression of tissue factor contributing to thrombotic processes and a procoagulant state, respectively. Complement activation also promotes recruitment and activation of leukocytes resulting in oxidative burst and release of pro-inflammatory cytokines and chemokines, thereby worsening the elevated underlying inflammation and oxidative stress condition of chronic kidney disease patients. Restricting all forms of blood-incompatibility, including potential contamination of dialysis fluid with endotoxins leading to inflammation, during HD therapies is thus still a major target towards more blood-compatible and safer dialysis to improve patient outcomes. We describe the mechanisms of various activation pathways during the interaction between blood and components of the ECC and describe approaches to mitigate the effects of these adverse interactions. The opportunities to develop improved dialysis membranes as well as implementation strategies with less potential for undesired biological reactions are discussed.

Iron status, fibroblast growth factor 23 and cardiovascular and kidney outcomes in chronic kidney disease

Disordered iron and mineral homeostasis are interrelated complications of chronic kidney disease that may influence cardiovascular and kidney outcomes. In a prospective analysis of 3747 participants in the Chronic Renal Insufficiency Cohort Study, we investigated risks of mortality, heart failure, end-stage kidney disease (ESKD), and atherosclerotic cardiovascular disease according to iron status, and tested for mediation by C-terminal fibroblast growth factor 23 (FGF23), hemoglobin and parathyroid hormone. Study participants were agnostically categorized based on quartiles of transferrin saturation and ferritin as: "Iron Replete" (27.1% of participants; referent group for all outcomes analyses), "Iron Deficiency" (11.1%), "Functional Iron Deficiency" (7.6%), "Mixed Iron Deficiency" (iron indices between the Iron Deficiency and Functional Iron Deficiency groups; 6.3%), "High Iron" (9.2%), or "Non-Classified" (the remaining 38.8% of participants). In multivariable-adjusted Cox models, Iron Deficiency independently associated with mortality (hazard ratio 1.28, 95% confidence interval 1.04-1.58) and heart failure (1.34, 1.05- 1.72). Mixed Iron Deficiency associated with mortality (1.61, 1.27-2.04) and ESKD (1.33, 1.02-1.73). High Iron associated with mortality (1.54, 1.24-1.91), heart failure (1.58, 1.21-2.05), and ESKD (1.41, 1.13-1.77). Functional Iron Deficiency did not significantly associate with any outcome, and no iron group significantly associated with atherosclerotic cardiovascular disease. Among the candidate facilitators, FGF23 most significantly mediated the risks of mortality and heart failure conferred by Iron Deficiency. Thus, alterations in iron homeostasis associated with adverse cardiovascular and kidney outcomes in patients with chronic kidney disease.

Managing Anemia across the Stages of Kidney Disease in Those Hyporesponsive to Erythropoiesis-Stimulating Agents

BACKGROUND

Patients with CKD frequently have anemia that results from iron-restricted erythropoiesis and inflammation. Anemia of CKD is currently managed with iron supplements and erythropoiesis-stimulating agents (ESAs) to promote erythropoiesis and with RBC transfusion in severe cases. Hyporesponse to ESAs, or the need for larger than usual doses to attain a given hemoglobin (Hb) level, is associated with increased morbidity and mortality and presents a pressing clinical challenge, particularly for patients on dialysis. This paper reviews ESA hyporesponse and potential new therapeutic options in the management of anemia of CKD.

SUMMARY

The most common causes of ESA hyporesponse include iron deficiency and inflammation, and to a lesser degree, secondary hyperparathyroidism, inadequate dialysis, malnutrition, and concomitant medications. Management of ESA hyporesponse is multipronged and involves treating low level infections, ensuring adequate nutrition, and optimizing iron status and dialysis modality, although some patients can remain refractory. Inflammation directly increases production and secretion of hepcidin, contributes to an impaired response to hypoxia, and suppresses proliferation of erythroid progenitors. Coordination of renal and hepatic erythropoietin (EPO) production and iron metabolism is under the control of hypoxia-inducible factors (HIF), which are in turn regulated by HIF-prolyl hydroxylases (HIF-PHs). HIF-PHs and hepcidin are therefore attractive potential drug targets particularly in patients with ESA hyporesponse. Several oral HIF-PH inhibitors have been evaluated in patients with anemia of CKD and have been shown to increase Hb and reduce hepcidin regardless of inflammation, iron status, or dialysis modality. These sustained effects are achieved through more modest increases in endogenous EPO compared with ESAs. Key Messages: Treatments that address ESA hyporesponse remain a significant unmet clinical need in patients with anemia of CKD. New therapies such as HIF-PH inhibitors have the potential to address fundamental aspects of ESA hyporesponse and provide a new therapeutic option in these patients.

Chronic Kidney Disease Induced by Cisplatin, Folic Acid and Renal Ischemia Reperfusion Induces Anemia and Promotes GATA-2 Activation in Mice

Anemia is a common feature of chronic kidney disease (CKD). It is a process related to erythropoietin deficiency, shortened erythrocyte survival, uremic erythropoiesis inhibitors, and disordered iron homeostasis. Animal models of CKD-induced anemia are missing and would be desirable in order to study anemia mechanisms and facilitate the development of novel therapeutic tools. We induced three different models of CKD in mice and evaluated the development of anemia characteristics. Mice were subjected to unilateral ischemia-reperfusion or received repeated low doses of cisplatin or folic acid to induce nephropathy. Renal function, kidney injury and fibrotic markers were measured to confirm CKD. Moreover, serum hemoglobin, ferritin and erythropoietin were analyzed. Renal mRNA levels of HIF-2α, erythropoietin, hepcidin, GATA-2, and GATA-2 target genes were also determined. All three CKD models presented increased levels of creatinine, urea, and proteinuria. Renal up-regulation of NGAL, KIM-1, and TNF-α mRNA levels was observed. Moreover, the three CKD models developed fibrosis and presented increased fibrotic markers and α-SMA protein levels. CKD induced decreased hemoglobin and ferritin levels and increased erythropoietin levels in the serum. Renal tissue showed decreased erythropoietin and HIF-2α mRNA levels, while an increase in the iron metabolism regulator hepcidin was observed. GATA-2 transcription factor (erythropoietin repressor) mRNA levels were increased in all CKD models, as well as its target genes. We established three models of CKD-induced anemia, regardless of the mechanism and severity of kidney injury.

Potential effective treatment of shortening continuous erythropoietin receptor activator treatment interval combined with iron supplementation in hemodialysis patients

Our previous randomized controlled trial comparing the total dose of weekly versus biweekly continuous erythropoietin receptor activator (CERA) therapy to maintain optimal hemoglobin (Hb) levels showed no significant differences between the two therapies. This post-hoc analysis assessed whether the total dose of weekly versus biweekly CERA therapy to maintain Hb levels among HD patients differed among groups with or without iron supplementation. Of 107 patients, 40 received intravenous iron supplementation due to iron deficiency (iron group) and 67 did not (non-iron group). In the iron group, the weekly therapy tended to require a lower total CERA dose compared with the biweekly therapy (274 ± 274 vs 381 ± 223 μg/12 weeks, P = 0.051). Changes in circulating hepcidin levels, a negative regulator of intestinal iron uptake, after 2 weeks of CERA treatment were significantly lower in the weekly therapy compared with the biweekly therapy (-4.2 ± 6.3 vs 11.1 ± 7.3 ng/mL, P = 0.015). In the non-iron group, there were no significant differences in total CERA dose or changes in hepcidin levels between the two therapies. Shortening the CERA treatment interval combined with iron supplementation may lead to the more efficient treatment of HD patients with iron deficiency.

Ironing out mechanisms of iron homeostasis and disorders of iron deficiency

Iron plays an important role in mammalian physiological processes. It is a critical component for the function of many proteins, including enzymes that require heme and iron-sulfur clusters. However, excess iron is also detrimental because of its ability to catalyze the formation of reactive oxygen species. As a result, cellular and systemic iron levels are tightly regulated to prevent oxidative damage. Iron deficiency can lead to a number of pathological conditions, the most prominent being anemia. Iron deficiency should be corrected to improve adult patients' symptoms and to facilitate normal growth during fetal development and childhood. However, inappropriate use of intravenous iron in chronic conditions, such as cancer and heart failure, in the absence of clear iron deficiency can lead to unwanted side effects. Thus, this form of therapy should be reserved for certain patients who cannot tolerate oral iron and need rapid iron replenishment. Here, we will review cellular and systemic iron homeostasis and will discuss complications of iron deficiency.

Interleukin-6 Signaling and Anti-Interleukin-6 Therapeutics in Cardiovascular Disease

IL (interleukin)-6 is a pivotal cytokine of innate immunity, which enacts a broad set of physiological functions traditionally associated with host defense, immune cell regulation, proliferation, and differentiation. Following recognition of innate immune pathways leading from the NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome to IL-1 to IL-6 and on to the hepatically derived clinical biomarker CRP (C-reactive protein), an expanding literature has led to understanding of the proatherogenic role for IL-6 in cardiovascular disease and thus the potential for IL-6 inhibition as a novel method for vascular protection. In this review, we provide an overview of the mechanisms by which IL-6 signaling occurs and how that impacts upon pharmacological inhibition; describe murine models of IL-6 and atherogenesis; summarize human epidemiological data outlining the utility of IL-6 as a biomarker of vascular risk; outline genetic data suggesting a causal role for IL-6 in systemic atherothrombosis and aneurysm formation; and then detail the potential role of IL-6 inhibition in stable coronary disease, acute coronary syndromes, heart failure, and the atherothrombotic complications associated with chronic kidney disease and end-stage renal failure. Finally, we review anti-inflammatory and antithrombotic findings for ziltivekimab, a novel IL-6 ligand inhibitor being developed specifically for use in atherosclerotic disease and poised to be tested formally in a large-scale cardiovascular outcomes trial focused on individuals with chronic kidney disease and elevated levels of CRP, a population at high residual atherothrombotic risk, high residual inflammatory risk, and considerable unmet clinical need.

Types of erythropoiesis-stimulating agents and risk of end-stage kidney disease and death in patients with non-dialysis chronic kidney disease

BACKGROUND

Despite the widespread use of erythropoiesis-stimulating agents (ESAs) to treat anaemia, the risk of adverse outcomes associated with the use of different types of ESAs in non-dialysis chronic kidney disease (CKD) is poorly investigated.

METHODS

From a pooled cohort of four observational studies, we selected CKD patients receiving short-acting (epoetin α/β; n = 299) or long-acting ESAs (darbepoetin and methoxy polyethylene glycol-epoetin β; n = 403). The primary composite endpoint was end-stage kidney disease (ESKD; dialysis or transplantation) or all-cause death. Multivariable Cox models were used to estimate the relative risk of the primary endpoint between short- and long-acting ESA users.

RESULTS

During follow-up [median 3.6 years (interquartile range 2.1-6.3)], the primary endpoint was registered in 401 patients [166 (72%) in the short-acting ESA group and 235 (58%) in the long-acting ESA group]. In the highest tertile of short-acting ESA dose, the adjusted risk of primary endpoint was 2-fold higher {hazard ratio [HR] 2.07 [95% confidence interval (CI) 1.37-3.12]} than in the lowest tertile, whereas it did not change across tertiles of dose for long-acting ESA patients. Furthermore, the comparison of ESA type in each tertile of ESA dose disclosed a significant difference only in the highest tertile, where the risk of the primary endpoint was significantly higher in patients receiving short-acting ESAs [HR 1.56 (95% CI 1.09-2.24); P = 0.016]. Results were confirmed when ESA dose was analysed as continuous variable with a significant difference in the primary endpoint between short- and long-acting ESAs for doses >105 IU/kg/week.

CONCLUSIONS

Among non-dialysis CKD patients, the use of a short-acting ESA may be associated with an increased risk of ESKD or death versus long-acting ESAs when higher ESA doses are prescribed.

In-depth review: is hepcidin a marker for the heart and the kidney?

Iron is an essential trace element involved in oxidation-reduction reactions, oxygen transport and storage, and energy metabolism. Iron in excess can be toxic for cells, since iron produces reactive oxygen species and is important for survival of pathogenic microbes. There is a fine-tuning in the regulation of serum iron levels, determined by intestinal absorption, macrophage iron recycling, and mobilization of hepatocyte stores versus iron utilization, primarily by erythroid cells in the bone marrow. Hepcidin is the major regulatory hormone of systemic iron homeostasis and is upregulated during inflammation. Hepcidin metabolism is altered in chronic kidney disease. Ferroportin is an iron export protein and mediates iron release into the circulation from duodenal enterocytes, splenic reticuloendothelial macrophages, and hepatocytes. Systemic iron homeostasis is controlled by the hepcidin-ferroportin axis at the sites of iron entry into the circulation. Hepcidin binds to ferroportin, induces its internalization and intracellular degradation, and thus inhibits iron absorption from enterocytes, and iron release from macrophages and hepatocytes. Recent data suggest that hepcidin, by slowing or preventing the mobilization of iron from macrophages, may promote atherosclerosis and may be associated with increased cardiovascular disease risk. This article reviews the current data regarding the molecular and cellular pathways of systemic and autocrine hepcidin production and seeks the answer to the question whether changes in hepcidin translate into clinical outcomes of all-cause and cardiovascular mortality, and cardiovascular and renal end-points.

Iron deficiency in heart failure

Iron deficiency is a major heart failure co‐morbidity present in about 50% of patients with stable heart failure irrespective of the left ventricular function. Along with compromise of daily activities, it also increases patient morbidity and mortality, which is independent of anaemia. Several trials have established parenteral iron supplementation as an important complimentary therapy to improve patient well‐being and physical performance. Intravenous iron preparations, in the first‐line ferric carboxymaltose, demonstrated in previous clinical trials superior clinical effect in comparison with oral iron preparations, improving New York Heart Association functional class, 6 min walk test distance, peak oxygen consumption, and quality of life in patients with chronic heart failure. Beneficial effect of iron deficiency treatment on morbidity and mortality of heart failure patients is waiting for conformation in ongoing trials. Although the current guidelines for treatment of chronic and acute heart failure acknowledge importance of iron deficiency correction and recommend intravenous iron supplementation for its treatment, iron deficiency remains frequently undertreated and insufficiently diagnosed in setting of the chronic heart failure. This paper highlights the current state of the art in the pathophysiology of iron deficiency, associations with heart failure trajectory and outcome, and an overview of current guideline‐suggested treatment options.

Anaemia and iron deficiency in patients with rheumatoid arthritis and other chronic diseases

Anaemia is one of the most common symptoms accompanying many chronic diseases, e.g. collagenases, neoplasms, and chronic inflammations (inflammatory bowel disease, chronic kidney disease and heart failure). Iron deficiency anaemia is the most common type of anaemia (80%). It affects 1% to 2% of the population. Iron deficiency (ID) – absolute or functional – is characterised by reduced ferritin levels and transferrin saturation (TSAT) of less than 20%. Iron deficiency is the most common dietary deficiency. However, iron deficiency might be one of the common causes of anaemia of chronic disease (ACD). Anaemia affects 33% to 60% of patients with RA. Rheumatoid arthritis (RA) is a chronic immune-mediated systemic connective tissue disease, in which chronic inflammation of the synovial tissue of the joints damages articular cartilages, bones and other joint structures. The prevalence of RA is approximately 0.3% to 2%. Low haemoglobin levels in RA patients are significantly correlated with disability, activity and duration of the disease as well as damage to joints and joint pain. Treatment of anaemia in RA patients includes iron supplementation, blood transfusions, the use of erythropoiesis-stimulating agents, and treatment of the underlying condition. Biological treatments used in RA patients, such as e.g. infliximab, tocilizumab and anakinra, not only slow the progression of joint involvement but also prevent anaemia.

The Association between Serum Hemoglobin and Renal Prognosis of IgA Nephropathy

Immunoglobin A (IgA) nephropathy causes chronic kidney disease worldwide. Therefore, identifying risk factors associated with the progression of IgA nephropathy is crucial. Anemia is a common complication of chronic kidney disease; however, few studies have investigated the effect of serum hemoglobin on the renal prognosis of IgA nephropathy. This study aimed to determine the effect of serum hemoglobin on the progression of IgA nephropathy. We retrospectively analyzed 4326 patients with biopsy-proven IgA nephropathy. We evaluated the effect of serum hemoglobin on IgA nephropathy progression using Kaplan-Meier survival analyses, the log-rank test, and the Cox proportional hazards model. The primary end-point was progression of IgA nephropathy, defined as dialysis initiation or kidney transplantation. Serum hemoglobin showed a nonlinear relationship with the progression of IgA nephropathy. The Cox proportional hazards model showed that the risk of progression of IgA nephropathy decreased 0.87 times for every 1.0 g/dL increase in serum hemoglobin. In subgroup analyses, reduced serum hemoglobin was an independent risk factor for IgA nephropathy progression only in women. There was no statistically significant interaction of serum hemoglobin between men and women (P _interaction = 0.177). Results of Sensitivity analysis were robust and consistent. Serum hemoglobin at diagnosis was an independent predictor for IgA nephropathy progression.

Vitamin A deficiency regulates the expression of ferritin in young male Wistar rats

ABSTRACT Objective Iron deficiency and vitamin A deficiency are two of the main micronutrient deficiencies. Both micronutrients are essential for human life and children's development. This study aimed to investigate the effects of vitamin A deficiency on ferritin and transferrin receptors' expression and its relationship with iron deficiency. Methods Five diets with different vitamin A-to-iron ratios were given to thirty five 21-day-old male Wistar rats (separated in groups of seven animals each). The animals received the diet for six weeks before being euthanized. Serum iron and retinol levels were measured as biochemical parameters. Their duodenums, spleens, and livers were analyzed for the expression of ferritin and transferrin receptors by Western Blotting. Results Regarding biochemical parameters, the results show that when both vitamin A and iron are insufficient, the serum iron content (74.74µg/dL) is significantly lower than the control group (255.86µg/dL). The results also show that vitamin A deficiency does not influence the expression of the transferrin receptor, but only of the ferritin one. Conclusion Vitamin A deficiency regulates the expression of ferritin in young male Wistar rats.

The potential role of Na-K-ATPase and its signaling in the development of anemia in chronic kidney disease

Chronic kidney disease (CKD) is one of the most prominent diseases affecting our population today. According to the Factsheet published by Centers for Disease Control and Prevention (CDC), it effects approximately 15% of the total population in the United States in some way, shape, or form. Within the myriad of symptomatology associated with CKD, one of the most prevalent factors in terms of affecting quality of life is anemia. Anemia of CKD cannot be completely attributed to one mechanism or cause, but rather has a multifactorial origin in the pathophysiology of CKD. While briefly summarizing well-documented risk factors, this review, as a hypothesis, aims to explore the possible role of Na-K-ATPase and its signaling function [especially recent identified reactive oxygen species (ROS) amplification function] in the interwoven mechanisms of development of the anemia of CKD.

Plasma Protein Carbonyls as Biomarkers of Oxidative Stress in Chronic Kidney Disease, Dialysis, and Transplantation

Accumulating evidence indicates that oxidative stress plays a role in the pathophysiology of chronic kidney disease (CKD) and its progression; during renal replacement therapy, oxidative stress-derived oxidative damage also contributes to the development of CKD systemic complications, such as cardiovascular disease, hypertension, atherosclerosis, inflammation, anaemia, and impaired host defence. The main mechanism underlying these events is the retention of uremic toxins, which act as a substrate for oxidative processes and elicit the activation of inflammatory pathways targeting endothelial and immune cells. Due to the growing worldwide spread of CKD, there is an overwhelming need to find oxidative damage biomarkers that are easy to measure in biological fluids of subjects with CKD and patients undergoing renal replacement therapy (haemodialysis, peritoneal dialysis, and kidney transplantation), in order to overcome limitations of invasive monitoring of CKD progression. Several studies investigated biomarkers of protein oxidative damage in CKD, including plasma protein carbonyls (PCO), the most frequently used biomarker of protein damage. This review provides an up-to-date overview on advances concerning the correlation between plasma protein carbonylation in CKD progression (from stage 1 to stage 5) and the possibility that haemodialysis, peritoneal dialysis, and kidney transplantation improve plasma PCO levels. Despite the fact that the role of plasma PCO in CKD is often underestimated in clinical practice, emerging evidence highlights that plasma PCO can serve as good biomarkers of oxidative stress in CKD and substitutive therapies. Whether plasma PCO levels merely serve as biomarkers of CKD-related oxidative stress or whether they are associated with the pathogenesis of CKD complications deserves further evaluation.

Comparison of the effects of zinc oxide and zinc oxide nanoparticles on the expression of hepcidin gene in rat liver

OBJECTIVES

Nanoparticles have special properties, such as increased intestinal absorption, permeability, and so on. Zinc oxide (ZnO) nanoparticles have medical applications such as using in drug production. Studies of ZnO nanoparticles have shown the role of these particles in reducing or increasing the genes expression. Given the important role of hepcidin in the development of anemia and iron overload diseases, this study investigated the effect of ZnO nanoparticles on the hepatic expression of the hepcidin gene to help find a way to treat these diseases.

METHODS

In this experimental study, 24 male Westar rats were divided into three groups: control, ZnO treating group and ZnO nanoparticle treating group. Both ZnO and ZnO nanoparticles were injected with 50 mg/kg body weight for 14 days. At the end, serums were collected and iron, ferritin and IL-6 levels were measured. Expression of the hepcidin gene was done by Real Time PCR.

RESULTS

ZnO and the ZnO nanoparticle significantly increased the expression of the hepcidin gene relative to the control group. The increase in expression of the hepcidin gene in ZnO nanoparticles was more significant than in the ZnO.

CONCLUSION

ZnO nanoparticles led to significant increase in expression of the hepcidin gene.

Effects of hypoxia-inducible factor prolyl hydroxylase inhibitors on iron regulation in non-dialysis-dependent chronic kidney disease patients with anemia: A systematic review and meta-analysis

Phase 2 and phase 3 clinical studies showed that hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) efficiently increased hemoglobin levels in both dialysis-dependent and non-dialysis-dependent chronic kidney disease (CKD) patients. However, the effects of HIF-PHIs on iron regulation have not been consistent among clinical trials. We performed a systematic review and meta-analysis of randomized controlled trials to evaluate the effects of six HIF-PHIs on iron regulation in non-dialysis CKD patients. Electronic databases were searched from inception to April 20, 2020, for eligible studies. Changes from baseline in transferrin saturation (TSAT), total iron-binding capacity (TIBC), iron, ferritin, and hepcidin levels were pooled using the inverse-variance method and presented as the mean difference (MD) or standardized MD (SMD) with 95 % confidence intervals (CIs). Meta-analysis of the included studies showed that, in non-dialysis-dependent CKD patients, HIF-PHIs decreased TSAT (MD, -4.51; 95 % CI, -5.81 to -3.21), ferritin (MD, -47.29; 95 % CI, -54.59 to -40.00) and hepcidin (SMD, -0.94; 95 % CI, -1.25 to -0.62), increased TIBC (MD, 9.15; 95 % CI, 7.08-11.22), and did not affect serum iron (MD, -0.31; 95 % CI, -2.05 to 1.42) despite enhanced erythropoiesis. This systematic review suggests that HIF-PHIs promote iron utilization in non-dialysis-dependent CKD patients. Importantly, HIF-PHIs are associated with increased transferrin levels (and TIBC), leading to reduced TSAT. Therefore, the reduction of TSAT after HIF-PHIs should not be interpreted as iron deficiency.

Iron Metabolism in Obesity and Metabolic Syndrome

Obesity is an excessive adipose tissue accumulation that may have detrimental effects on health. Particularly, childhood obesity has become one of the main public health problems in the 21st century, since its prevalence has widely increased in recent years. Childhood obesity is intimately related to the development of several comorbidities such as nonalcoholic fatty liver disease, dyslipidemia, type 2 diabetes mellitus, non-congenital cardiovascular disease, chronic inflammation and anemia, among others. Within this tangled interplay between these comorbidities and associated pathological conditions, obesity has been closely linked to important perturbations in iron metabolism. Iron is the second most abundant metal on Earth, but its bioavailability is hampered by its ability to form highly insoluble oxides, with iron deficiency being the most common nutritional disorder. Although every living organism requires iron, it may also cause toxic oxygen damage by generating oxygen free radicals through the Fenton reaction. Thus, iron homeostasis and metabolism must be tightly regulated in humans at every level (i.e., absorption, storage, transport, recycling). Dysregulation of any step involved in iron metabolism may lead to iron deficiencies and, eventually, to the anemic state related to obesity. In this review article, we summarize the existent evidence on the role of the most recently described components of iron metabolism and their alterations in obesity.

Host-Pathogen Interaction as a Novel Target for Host-Directed Therapies in Tuberculosis

Tuberculosis (TB) has been a transmittable human disease for many thousands of years, and M. tuberculosis is again the number one cause of death worldwide due to a single infectious agent. The intense 6- to 10-month process of multi-drug treatment, combined with the adverse side effects that can run the spectrum from gastrointestinal disturbances to liver toxicity or peripheral neuropathy are major obstacles to patient compliance and therapy completion. The consequent increase in multidrug resistant TB (MDR-TB) and extensively drug resistant TB (XDR-TB) cases requires that we increase our arsenal of effective drugs, particularly novel therapeutic approaches. Over the millennia, host and pathogen have evolved mechanisms and relationships that greatly influence the outcome of infection. Understanding these evolutionary interactions and their impact on bacterial clearance or host pathology will lead the way toward rational development of new therapeutics that favor enhancing a host protective response. These host-directed therapies have recently demonstrated promising results against M. tuberculosis, adding to the effectiveness of currently available anti-mycobacterial drugs that directly kill the organism or slow mycobacterial replication. Here we review the host-pathogen interactions during M. tuberculosis infection, describe how M. tuberculosis bacilli modulate and evade the host immune system, and discuss the currently available host-directed therapies that target these bacterial factors. Rather than provide an exhaustive description of M. tuberculosis virulence factors, which falls outside the scope of this review, we will instead focus on the host-pathogen interactions that lead to increased bacterial growth or host immune evasion, and that can be modulated by existing host-directed therapies.

Vitamin A does not influence mRNA expression of hormone hepcidin but other biomarkers of iron homeostasis in young male Wistar rats

The effects of an adequate supply of vitamin A and iron, in comparison with diets low or absent in vitamin A and low in iron, on the mRNA expression of some biomarkers of iron homeostasis as hepcidin (Hamp), transferrin receptor-1 (Tfrc), iron regulatory protein-2 (Ireb2) and ferritin (Fth1) in rats were investigated. 35 male Wistar rats were randomly divided into 5 dietary groups: control, sufficient in iron and insufficient in vitamin A (FesvAi), sufficient in iron and depleted in vitamin A (FesvAd), insufficient in iron and sufficient in vitamin A (FeivAs) and insufficient in both iron and vitamin A (FeivAi). After 6 weeks rats showed no significant effects of variations in vitamin A on the expression of Hamp relative to the control group (FesvAi: 1.37-fold; FesvAd: 1.22-fold); however, iron deficiency showed significant reduction on it relative to the control group (FeivAs: 71.4-fold, P = 0.0004; FeivAi: 16.1-fold, P = 0.0008). Vitamin A deficiency (FesvAd) affects expression of Fth1 independent of low dietary iron in spleen (0.29-fold, P = 0.002) and duodenum (5.15-fold, P = 0.02). Variations of dietary iron and vitamin A showed significant effects relative to the control group for expression of Tfrc in spleen (FesvAd: 0.18-fold, P = 0.01; FeivAs: 0.24-fold, P < 0.0001; FeivAi: 0.42-fold, P = 0.014), Ireb2 in spleen (FeivAs: 3.7-fold, P < 0.0001; FeivAi: 2.9-fold, P < 0.0001) and Ireb2 in duodenum (FeivAs: 2.68-fold, P = 0.012; FeivAi: 2.60-fold, P = 0.014). These results show that vitamin A and iron must be supplied together to regulate some of the main biomarkers of iron metabolism as a strategy to reduce prevalence of iron deficiency anemia.

IL-1β Drives Production of FGF-23 at the Onset of Chronic Kidney Disease in Mice

FGF-23 has arisen as an early biomarker of renal dysfunction, but at the onset of chronic kidney disease (CKD), data suggest that FGF-23 may be produced independently of the parathyroid hormone (PTH), 1,25(OH)₂ -vitamin D₃ signaling axis. Iron status is inversely correlated to the level of circulating FGF-23, and improvement in iron bioavailability within patients correlates with a decrease in FGF-23. Alternately, recent evidence also supports a regulatory role of inflammatory cytokines in the modulation of FGF-23 expression. To determine the identity of the signal from the kidney-inducing upregulation of osteocytic FGF-23 at the onset of CKD, we utilized a mouse model of congenital CKD that fails to properly mature the glomerular capillary tuft. We profiled the sequential presentation of indicators of renal dysfunction, phosphate imbalance, and iron bioavailability and transport to identify the events that initiate osteocytic production of FGF-23 during the onset of CKD. We report here that elevations in circulating intact-FGF-23 coincide with the earliest indicators of renal dysfunction (P14), and precede changes in serum phosphate or iron homeostasis. Serum PTH was also not changed within the first month. Instead, production of the inflammatory protein IL-1β from the kidney and systemic elevation of it in the circulation matched the induction of FGF-23. IL-1β's ability to induce FGF-23 was confirmed on bone chips in culture and within mice in vivo. Furthermore, neutralizing antibody to IL-1β blocked FGF-23 expression in both our congenital model of CKD and a second nephrotoxic serum-mediated model. We conclude that early CKD resembles a situation of primary FGF-23 excess mediated by inflammation. These findings do not preclude that altered mineral availability or anemia can later modulate FGF-23 levels but find that in early CKD they are not the driving stimulus for the initial upregulation of FGF-23. © 2020 American Society for Bone and Mineral Research.

Dietary Habit and Other Risk Factors of Chronic Kidney Disease Among Patients Attending Dessie Referral Hospital, Northeast Ethiopia

Background

In low- and middle-income countries, the burden of chronic kidney disease (CKD) is rising due to poor access to early detection and management services. In Ethiopia, little is known about the context-specific risk factors and their magnitude, particularly the dietary habit of patients is not studied. Therefore, this study aimed to identify the dietary and other risk factors of CKD in Northeast Ethiopia.

Methods

We conducted a facility-based unmatched case–control study utilizing quantitative method of data collection. Data were collected on a total of 66 cases and 134 controls using structured questionnaire and anthropometric measurements. Dietary habit was assessed using the Diet History Questionnaire (DHQ). Medical history, patient chart review and physical examination were employed to collect other relevant information. To identify independent predictors of CKD, we conducted a multivariable logistic regression analysis.

Results

About 54.5% cases and 46.3% of controls were female, while 40.9% of cases and 38.8% of controls were within the age group of 36–55. All cases and 128 (95.5%) controls consumed meat in the last year. Forty-six (69.7%) cases and 74 (55.2%) controls use palm oil as the main cooking oil. History of hypertension (adjusted odds ratio (AOR)=2.39; 95%CI: 1.17–4.89), anemia (AOR=2.38; 95%CI: 1.04–5.42), palm oil use (AOR=2.10; 95%CI: 1.01–4.35) and family history of CKD (AOR=8.77; 95%CI: 3.73–20.63) were significantly associated with the risk of having CKD.

Conclusion

Meat consumption and use of palm oil are higher among patients with CKD than controls. History of hypertension, anemia, family history of CKD and palm oil consumption were found to be risk factors for CKD. Dietary counseling interventions and dietary modifications might help in CKD prevention. Furthermore, routine urinalysis and estimation of glomerular filtration rate (GFR) for all hospitalized patients with hypertension and anemia could help to detect CKD at an earlier stage for a better prognosis.

Genetic analysis of TMPRSS6 gene in Saudi female patients with iron deficiency anemia

OBJECTIVE/BACKGROUND

Mutations in transmembrane protease serine 6 (TMPRSS6) gene induce high hepcidin level, which causes iron-refractory iron deficiency anemia (IRIDA) by preventing duodenal iron absorption. This study aims to identify the common genetic variations of the TMPRSS6 gene that affect iron levels among Saudi female patients with iron deficiency anemia (IDA).

METHODS

All study participants were Saudi females (12-49 years old): 32 patients with IDA, 32 patients with IRIDA, and 34 healthy individuals comprising the control group. Hematological investigations, iron profile, serum hepcidin level, and TMPRSS6 gene transcription were determined. The TMPRSS6 gene was amplified, sequenced, and analyzed among all study participants.

RESULTS

The mean hepcidin and TMPRSS6 RNA transcription levels in IDA and IRIDA groups were significantly lower than those in the control group. TMPRSS6 gene sequence analysis detected 41 variants: two in the 5' untranslated region (5'UTR), 17 in introns, and 22 in exons. Thirty-three variants were previously reported in the Single Nucleotide Polymorphism Database, and eight variants were novel; one novel variant was in 5'UTR (g.-2 T > G); five novel variants were detected in exons (p.W73X, p.D479N, p.E523K, p.L674L, and p.I799I). At the time of the sequence analysis of our samples, two variants-p.D479N and p.674L-were novel. However, these variants are present at a very low allele frequency in other populations (L674L, 0.00007761 and D479N, 0.000003980).

CONCLUSION

This is the first study to investigate the genetic variants of TMPRSS6 gene in Saudi female patients with IDA. The generated data will serve as a reference for future studies on IDA in the Arab population.

Management of Iron-Deficiency Anemia on Inpatients and Appropriate Discharge and Follow-Up

Background

The aims of the study were to identify appropriate supplementation of iron for inpatients and to identify factors involved in appropriate discharge documentation and follow-up.

Methods

This was a retrospective analysis of 103 patients at a community hospital in New York City.

Results

A total of 57 (57/103, 55.3%) patients were admitted due to symptomatic anemia. Twenty (20/103, 19.4%) of those with iron-deficiency anemia had either esophagogastroduodenoscopy or colonoscopy. Gastroenterologist or hematologist was consulted for 45/103 (43.7%). Inpatient iron supplementation was given for 62/103 (60.2%) of patients; and 43/103 (41.7%) had blood transfusion. Upon discharge, 50/103 (48.5%) had appropriate documentation of iron-deficiency anemia on discharge paperwork. Appropriate follow-up was done for 54/103 (52.4%). Iron supplementation was provided for 53/103 (51.5%) of patients. Having inpatient esophagogastroduodenoscopy or colonoscopy, blood transfusion, or symptomatic anemia had a statistical significance for likelihood of appropriate discharge documentation.

Conclusions

Iron-deficiency anemia can have high rates of mortality and morbidity in the population. Appropriate discharge of patients with iron-deficiency anemia and factors related to this are paramount for clinicians in order to have the best patient outcomes.

High dose of dietary vitamin D3 modulated the yellow catfish (Pelteobagrus fulvidraco) splenic innate immune response after Edwardsiella ictaluri infection

Vitamin D₃ (VD₃) has been shown to modulate the innate immune response in mammals but this has been rarely reported in fish. The current study found that increasing dietary VD₃ content can reduce the density of yellow to dark brown pigmented macrophage aggregates (PMAs) in the spleens of yellow catfish infected with Edwardsiella ictaluri. The results of next-generation sequencing showed that a high dose of dietary VD₃ (16,600 IU/kg) mainly affected the splenic immune response during Edwardsiella ictaluri infection via negative regulation of 'NF-κΒ transcription factor activity', 'NIK/NF-κΒ signaling' and the 'i-kappab kinase/NF-κΒ signaling' pathways. Follow-up qPCR showed that dietary VD₃ increased the expression of NF-κΒ inhibitor iκb-α, decreased the expression of nf-κb p65, il-6, il1-β and tnf-α, and down-regulated the expression of nik, ikks and nf-κb p52 in the NIK/NF-kappaB signaling pathway. The above results indicate that dietary VD₃ can modulate the splenic innate immune response of yellow catfish after Edwardsiella ictaluri infection by inhibiting the NF-κB activation signaling pathways.

Tc-99m TRODAT-1 SPECT is a Potential Biomarker for Restless Leg Syndrome in Patients with End-Stage

Rationales: Restless leg syndrome (RLS) is a common complication in patients with end-stage renal disease (ESRD). However, there is a lack of biomarkers linking uremic RLS to dopaminergic neurons. Previous studies demonstrated that Tc-99m TRODAT-1 SPECT was a biomarker for RLS but the correlation between the physiologic parameter was lacking. Methods: Overall, 32 patients were enrolled in the study and divided into the following 3 groups: (1) control (n = 13), (2) ESRD without RLS (n = 8) and (3) ESRD with RLS (n = 11). All patients had a clinical diagnosis of RLS and received Tc-99m TRODAT-1 SPECT. A subgroup analysis was performed to compare differences between the control and ESRD with RLS groups. Tc-99m TRODAT-1 SPECT was performed and activities in the striatum and occipital areas were measured using manually delineated regions of interest (ROIs) by an experienced nuclear medicine radiologist who was blinded to clinical data. Results: The total ratio of Tc-99m TRODAT SPECT was lower in the ESRD with RLS group (p = 0.046). The uptake ratio of TRODAT negatively correlated with serum parathyroid hormone (r = −0.577, p = 0.015) and ferritin (r = −0.464, p = 0.039) concentrations. However, the uptake positively correlated with the hemoglobin concentration (r = 0.531, p = 0.011). The sensitivity and specificity of the total TRODAT ratio for predicting RLS in the overall population were 95.0% and 67.7%, respectively, at a cutoff value of 0.980 (area under the curve of receiver operating characteristic curve was 0.767, p = 0.024). Conclusion: In patients with ESRD and RLS, Tc-99m TRODAT might be a potential biomarker. Dysregulated hemoglobin, serum parathyroid hormone and serum ferritin concentrations might influence the uptake of the TRODAT ratio.

Safety of radiotherapy for hemodialysis patients with cancer

BACKGROUND

The number of hemodialysis (HD) patients is increasing worldwide, and they are at a higher risk of cancer than the general population. Because HD patients are more likely to have inflammation, radiotherapy (RT)-induced adverse effects (AEs) are theoretically expected to be worse for HD patients. Since only a few reports have been published on this subject, we aimed to evaluate the tolerability of RT in HD patients.

METHODS

We retrospectively analyzed AEs related to RT for HD patients. Our study included patients from three institutions treated between January 2007 and July 2017. The patient eligibility criteria were (i) receipt of maintenance HD 2-3 times per week for end-stage renal disease prior to the start of RT and (ii) pathologically confirmed malignancies. The endpoints were acute and late non-hematologic AEs.

RESULTS

The study included 56 patients. The most common histology was head and neck cancer (23%), followed by lung cancer (14%) and prostate cancer (11%). The median radiation dose was 60 (range, 12-93.8) Gy at an equivalent dose in 2-Gy fractions (EQD2). The RT completion rate was 96%. Patients had a median follow-up period after RT of 9.1 (range 0.5-98.1) months. Grade 3 or worse acute and late AEs were noted in 6 (11%) and 3 (7%) patients, respectively. In the acute phase, 2 patients had grade 5 AEs, both of which were infections.

CONCLUSION

Our results suggest that RT for HD patients is clinically tolerable. However, some patients can experience severe infections related to treatment.

Monitoring of iron status in patients with heart failure

The 2016 ESC/HFA heart failure (HF) guidelines emphasize the importance of identifying and treating iron deficiency (ID) in patients with HF. Iron deficiency can occur in half or more of HF sufferers, depending on age and the phase of the disease. Iron deficiency can be a cause of anaemia, but it is also common even without anaemia, meaning that ID is a separate entity, which should be screened for within the HF population. Although assessment of iron stores in bone marrow samples is the most accurate method to investigate iron status, it is not practical in most HF patients. Levels of circulating iron biomarkers are an easily available alternative; especially, ferritin and transferrin saturation (Tsat). In patients with HF serum ferritin level <100 µg/L (regardless of Tsat value) or between 100 and 299 µg/L with Tsat <20% are considered as recommended criteria for the diagnosis of ID, criteria which have been used in the clinical trials in HF that have led to a recommendation to treat ID with intravenous iron. We discuss the optimal measures of iron biomarkers in patients with HF in order to screen and monitor iron status and introduce some novel ways to assess iron status.

Anemia of Inflammation with An Emphasis on Chronic Kidney Disease

Iron is vital for a vast variety of cellular processes and its homeostasis is strictly controlled and regulated. Nevertheless, disorders of iron metabolism are diverse and can be caused by insufficiency, overload or iron mal-distribution in tissues. Iron deficiency (ID) progresses to iron-deficiency anemia (IDA) after iron stores are depleted. Inflammation is of diverse etiology in anemia of chronic disease (ACD). It results in serum hypoferremia and tissue hyperferritinemia, which are caused by elevated serum hepcidin levels, and this underlies the onset of functional iron-deficiency anemia. Inflammation is also inhibitory to erythropoietin function and may directly increase hepcidin level, which influences iron metabolism. Consequently, immune responses orchestrate iron metabolism, aggravate iron sequestration and, ultimately, impair the processes of erythropoiesis. Hence, functional iron-deficiency anemia is a risk factor for several ailments, disorders and diseases. Therefore, therapeutic strategies depend on the symptoms, severity, comorbidities and the associated risk factors of anemia. Oral iron supplements can be employed to treat ID and mild anemia particularly, when gastrointestinal intolerance is minimal. Intravenous (IV) iron is the option in moderate and severe anemic conditions, for patients with compromised intestinal integrity, or when oral iron is refractory. Erythropoietin (EPO) is used to treat functional iron deficiency, and blood transfusion is restricted to refractory patients or in life-threatening emergency situations. Despite these interventions, many patients remain anemic and do not respond to conventional treatment approaches. However, various novel therapies are being developed to treat persistent anemia in patients.

Evaluation of Iron Status in Patients of Chronic Kidney Disease - A Study to Assess the Best Indicators Including Serum Transferrin Receptor Assay

Anemia is an early complication of chronic kidney disease (CKD). The iron deficiency is an important contributor, more so in the Indian population. As routine standalone iron tests do not accurately reflect the actual status in the complex environment of CKD, there is a need to study better indicators. Serum iron, ferritin, total iron-binding capacity (TIBC), and serum transferrin receptor (sTfR) levels were estimated in 100 primary iron deficiency anemia (IDA) patients (controls-Group 1) and 68 newly diagnosed CKD cases. The CKD patients were divided into two groups: Serum ferritin <=100 μg/L (Group 2) and >100 μg/L (Group 3). The values of percentage saturation, log of ferritin (log_ferritin), and the ratio of sTfR to log ferritin (sTfR/log_f or sTfR index) were calculated. The CKD cases were further divided depending on ferritin cut-offs of 30, 50, 70, and 100 μg/L and statistically analyzed including ROC and AUC, to choose the best diagnostic parameter for accurate assessment of iron status in CKD cases. The mean serum ferritin was 11.34 μg/L, 28.70 μg/L, and 281.81 μg/L, and the mean sTfR was 2.34 μg/ml, 1.82 μg/ml, and 1.28 μg/ml in Groups 1, 2, and 3. Among all groups, the difference was found to be significant for serum iron, log_ferritin, and sTfR/log_f. The sTfR and sTfR/log_f showed good discrimination between IDA and Anemia of chronic disease in CKD cases, but sTfR/log_f gave the best discrimination at all cut-off levels of ferritin. At a ferritin cut-off of 50 μg/L, the sTfR/log_f value of 0.83 had a sensitivity of 93.5% and specificity of 95.45%, and at a ferritin cut-off 100 μg/L, the same value of 0.83 had a sensitivity of 95.5% and specificity of 86.5%. The ratio of sTfR/log_f is the best indicator for assessing iron status in CKD.

Anemia and iron deficiency among chronic kidney disease Stages 3-5ND patients in the Chronic Kidney Disease Outcomes and Practice Patterns Study: often unmeasured, variably treated

Background

International variation in anemia assessment and management practices in chronic kidney disease (CKD) is poorly understood.

Methods

We performed a cross-sectional analysis of anemia laboratory monitoring, prevalence and management in the prospective Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps). A total of 6766 participants with CKD Stages 3a–5ND from nephrology clinics in Brazil, France, Germany and the USA were included.

Results

Among patients with anemia (hemoglobin <12 g/dL), 36–58% in Brazil, the USA and Germany had repeat hemoglobin measured and 40–61% had iron indices measured within 3 months of the index hemoglobin measurement. Anemia was more common in the USA and Brazil than in France and Germany across CKD stages. Higher ferritin and lower iron saturation (TSAT) levels were observed with lower hemoglobin levels, and higher ferritin with more advanced CKD. The proportion of anemic patients with ferritin <100 ng/mL or TSAT <20% ranged from 42% in Brazil to 53% in France and Germany, and of these patients, over 40% in Brazil, Germany and the USA, compared with 27% in France, were treated with oral or intravenous iron within 3 months after hemoglobin measurement. The proportion of patients with hemoglobin <10 g/dL treated with erythropoiesis-stimulating agents ranged from 28% in the USA to 57% in Germany.

Conclusions

Hemoglobin and iron stores are measured less frequently than per guidelines. Among all regions, there was a substantial proportion of anemic patients with iron deficiency who were not treated with iron, highlighting an area for practice improvement in CKD care.

High Cardiovascular Risk Profile in Young Patients on the Kidney Transplant Waiting List

BACKGROUND

Cardiovascular complications are the leading causes of morbidity and mortality in patients with end-stage renal disease. The risk profile very often contributes to their death while on the waiting list. Most studies have been carried out in older patients with end-stage renal disease, reflecting the general dialysis population. The aim of this study was to analyze the risk profile in young patients with advanced chronic kidney disease on the kidney transplant waiting list.

METHODS

This was a retrospective, single-center study of 748 patients on the kidney transplant waiting list at the University Hospital Essen, Germany. Clinical and laboratory parameters were collected between 2015 and 2016.

RESULTS

Of 748 patients (62% male), the median age was 48 years. Hypertension, coronary heart disease, and diabetes mellitus were the leading comorbidities, and their frequency rose significantly with age. Their median laboratory values did not differ significantly depending on age except for albumin. Hyperuricemia was quite common in our population with a prevalence of about 75% in women and 50% in men throughout all age groups. A total of 26.6% of the patients between 18 and 35 years of age had advanced anemia (hemoglobin < 10 g/dL), and thus they were affected most frequently. Elevated C-reactive protein serum levels were observed in 37.2% of the patients. Regarding the lipid profile, we observed that HDL cholesterol was within the normal range in only among 51.9% of men and 44.3% of women.

CONCLUSIONS

Cardiovascular risk factors are quite common in our cohort and affect young patients similarly.

Serum Hepcidin-25 Levels Reflect the Presence of Bacteremia in Patients with Systemic Inflammatory Response Syndrome

BACKGROUND

Hepcidin-25 is a key regulatory hormone of iron homeostasis in humans, and its production is greatly upregulated by inflammation as well as iron overload. The aim of this study was to investigate the pathophysiological role of hepcidin-25 in patients with systemic inflammatory response syndrome (SIRS).

METHODS

We enrolled 113 consecutive patients (aged 63.4±21, 50 men, 63 women), with 2 or more SIRS criteria, who were admitted to our department of general medicine between August 1, 2015 and August 31, 2017. We measured complete blood cell count and serum levels of hepcidin-25, iron, iron-binding capacity, ferritin, blood urea nitrogen, creatinine, albumin, and C-reactive protein (CRP) on admission. The patients were divided into 3 group: a bacteremia group (27 patients), a culture-negative bacterial infection group (60 patients), and a non-bacterial infection group (26 patients).

RESULTS

Hepcidin-25 levels were found to be comparable in terms of SIRS criteria: 162 [2.8-579], 193 [2.24-409], and 180 [89.2-421] ng/mL in patients with 2, 3, and 4 criteria, respectively (P=0.533). However, hepcidin-25 levels were significantly higher in the bacteremia group (209 [56.7-579] ng/mL) than in either the culture-negative bacterial infection group (168 [2.24-418] ng/mL) or the non-bacterial infection group (142 [2.8-409] ng/mL). A significant positive correlation between hepcidin-25 and CRP levels was noted in the bacteremia group (r=0.528, P=0.005) and non-bacterial infection group (r=0.648, P<0.001). Moreover, iron and ferritin levels were significantly lower in the bacteremia group than in the non-bacterial infection group.

CONCLUSIONS

Our findings suggest that hepcidin-25 level may reflect the presence of bacteremia as well as the severity of inflammation in patients with SIRS.

Enarodustat, Conversion and Maintenance Therapy for Anemia in Hemodialysis Patients: A Randomized, Placebo-Controlled Phase 2b Trial Followed by Long-Term Trial

BACKGROUND

Enarodustat (JTZ-951) is an orally available hypoxia-inducible factor prolyl hydroxylase inhibitor that increases endogenous erythropoietin levels in the treatment of anemia associated with chronic kidney disease (CKD).

OBJECTIVE

A phase 2b study of enarodustat to assess the hemoglobin (Hb) response, safety, and maintenance dosage was conducted in Japanese anemic patients with hemodialysis-dependent CKD.

METHODS

Subjects receiving a stable dose of an erythropoiesis-stimulating agent were randomized to receive once-daily enarodustat at a dose of 2, 4, or 6 mg or placebo in a double-blind manner for 6 weeks (Period 1) followed by 24-week open treatment with enarodustat, adjusted in the range of 2-8 mg to maintain Hb within a target range (10.0-12.0 g/dL; Period 2).

RESULTS

Change in Hb from baseline increased with enarodustat dose in Period 1. In Period 2, the proportion of subjects who maintained their Hb level within the target range at the end of treatment was 65.1%. To maintain Hb levels within the target range over the course of Period 2, approximately 80% of subjects required 2 dose adjustments or fewer. Enarodustat decreased hepcidin and ferritin levels, increased total iron-binding capacity, and was generally well tolerated.

CONCLUSIONS

Enarodustat corrected and maintained Hb levels in anemic patients with hemodialysis-dependent CKD. Phase 3 studies of enarodustat are currently ongoing.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

Recombinant human erythropoietin free patients seem to restore the EPO-hepcidin axis that is critical for erythropoiesis. A specific combination of clinical and biological parameters may help to detect future rHU-EPO free patients.

Iron Deficiency Anemia in Chronic Kidney Disease

Iron deficiency anemia is a common complication of chronic kidney disease (CKD). CKD patients suffer from both absolute and functional iron deficiency. Absolute iron deficiency is defined by severely reduced or absent iron stores, while functional iron deficiency is defined by adequate iron stores but insufficient iron availability for incorporation into erythroid precursors. This is due to increased levels of hepcidin. Anemia in CKD is associated with an increased risk of morbidity and mortality. The association between anemia and mortality may be related to the severity of anemia. All CKD patients should be screened for anemia during the initial evaluation for CKD. Criteria used to define iron deficiency are different among CKD compared to normal renal function. Among CKD patients, absolute iron deficiency is defined when the transferrin saturation (TSAT) is ≤20% and the serum ferritin concentration is ≤100 ng/mL among predialysis and peritoneal dialysis patients or ≤200 ng/mL among hemodialysis patients. Functional iron deficiency, also known as iron-restricted erythropoiesis, is characterized by TSAT ≤20% and elevated ferritin levels. Iron supplementation is recommended for all CKD patients with anemia. There is general agreement according to guidelines that intravenous (i.v.) iron supplementation is the preferred method for CKD patients on dialysis (CKD stage 5D) and either i.v. or oral iron is recommended for patients with CKD ND (CKD stages 3-5). In this review we discuss the evidence base for these recommendations.