Hepcidin: clinical utility as a diagnostic tool and therapeutic target

Mitochondrial iron regulation as an emerging target in ischemia/reperfusion injury during kidney transplantation

The injury caused by ischemia and subsequent reperfusion (I/R) is inevitable during kidney transplantation and its current management remains unsatisfactory. Iron is considered to play a remarkable pathologic role in the initiation or progression of tissue damage induced by I/R, whereas the effects of iron-related therapy remain controversial owing to the complicated nature of iron's involvement in multiple biological processes. A significant portion of the cellular iron is located in the mitochondria, which exerts a central role in the development and progression of I/R injury. Recent studies of iron regulation associated with mitochondrial function represents a unique opportunity to improve our knowledge on the pathophysiology of I/R injury. However, the molecular mechanisms linking mitochondria to the iron homeostasis remain unclear. In this review, we provide a comprehensive analysis of the alterations to iron metabolism in I/R injury during kidney transplantation, analyze the current understanding of mitochondrial regulation of iron homeostasis and discussed its potential application in I/R injury. The elucidation of regulatory mechanisms regulating mitochondrial iron homeostasis will offer valuable insights into potential therapeutic targets for alleviating I/R injury with the ultimate aim of improving kidney graft outcomes, with potential implications that could also extend to acute kidney injury or other I/R injuries.

Evaluating the safety and efficacy of daprodustat for anemia of chronic kidney disease: a meta-analysis of randomized clinical trials

PURPOSE

Anemia of chronic kidney disease (CKD) has traditionally been treated with recombinant human erythropoietin (rhEPO). Recently, daprodustat, a hypoxia-inducible factor prolyl-hydroxylase inhibitor, has also been shown to increase hematocrit. It remains unclear whether daprodustat or rhEPO should be the treatment of choice for anemia of CKD. We aimed to assess the efficacy and cardiovascular safety of daprodustat versus rhEPO in CKD patients.

METHODS

Online databases were queried in April 2022 for articles comparing the efficacy and safety of daprodustat in DD-CKD and NDD-CKD subgroups. Results from trials were pooled using a random-effects model.

RESULTS

Data on 8245 CKD patients from eight clinical trials were included. Our results show that in comparison to rhEPO, daprodustat maintained the same efficacy in increasing hemoglobin levels in both the DD-CKD (MD: 0.10; 95% CI [- 0.13,0.34]; p = 0.50) and NDD-CKD (MD: - 0.01; 95% CI [- 0.38,0.35]; p = 0.95) subgroups. Daprodustat significantly lowered hepcidin levels and significantly increased TIBC in both subgroups. Additionally, daprodustat significantly reduced the incidence of major adverse cardiovascular events (MACE) (RR: 0.89; 95% CI: 0.89-0.98; p = 0.02) and its myocardial infarction (MI) component (RR: 0.74; 95% CI: 0.59-0.92; p = 0.006) in the DD-CKD subgroup.

CONCLUSION

Daprodustat has similar efficacy compared to rhEPO for the treatment of anemia of CKD. On treatment, the reduced experience of MACE was reported in DD-CKD patients as compared to rhEPO. Furthermore, effects on iron metabolism varied by parameter, with daprodustat being superior to rhEPO in some cases and inferior in others.

An Investigation into Possible Sex Differences in Association of Hemoglobin with Survival Among Hemodialysis Patients in the J-DOPPS Cohort

AIMS

Lower hemoglobin levels are common among females without kidney diseases. However, little is known about the sex-specific management of anemia in hemodialysis patients.

METHODS

This prospective cohort study investigated the role of sex differences in the association between categorical baseline or time-varying hemoglobin levels and all-cause mortality via cox regression using data from 6890 patients the Japan Dialysis Outcomes and Practice Patterns Study (J-DOPPS, 2005-2015). Likelihood ratio tests were used to evaluate the effect modification of sex on the relationship between hemoglobin and mortality.

RESULTS

A total of 781 patients died during the median follow-up of 31 months. Mortality risk, adjusted for case mix, varied between five hemoglobin categories, with the highest category (≥12 g/dl) having a hazard ratio of 0.73 (0.41-1.29) for females and 2.02 (1.03-3.95) for males versus 10-10.9 g/dl. Despite this difference, the p-value comparing the overall among males versus females was.35. Similar associations were observed in models stratified by patient age (<75 years), time on dialysis (≤1 year), and models lagging the hemoglobin exposure.

CONCLUSIONS

The results based on this sample of Japanese hemodialysis patients did not support the hypothesis that the association between hemoglobin and survival differed by sex. We also could not conclude that the association was identical, as the parameter estimates are consistent with male patients having a relatively greater mortality risk than female patients at higher hemoglobin levels. More detailed investigations into the effects of higher hemoglobin levels by sex might help better understand strategies for anemia management.

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.

Efficacy and Safety of Daprodustat Vs rhEPO for Anemia in Patients With Chronic Kidney Disease: A Meta-Analysis and Trial Sequential Analysis

Introduction: Daprodustat, a novel hypoxia-inducible factor prolyl-hydroxylase inhibitor (HIF-PHI), its efficacy and safety remain unclear. Thus, we conducted this meta-analysis aiming at investigating its efficacy and safety on the treatment of patients with chronic kidney disease (CKD)-related anemia.

Methods: We systematically searched for relevant studies in PubMed, Embase, Cochrane Library and Clinical Trial Registries databases from inception until December 2021. We selected randomized controlled trials comparing daprodustat with recombinant human erythropoietin (rhEPO) in anemia patients with CKD with or without dialysis.

Results: Seven studies including 7933 patients met the inclusion criteria. For both nondialysis-dependent (NDD-) CKD and dialysis-dependent (DD-) CKD patients, the pooled results showed that there was no significant difference in the changes in hemoglobin levels between the daprodustat and rhEPO groups (mean difference (MD) = −0.01, 95% confidence interval (CI) = −0.38, 0.35, p = 0.95; MD = 0.15, 95% CI = −0.29, 0.60, p = 0.50; respectively). In addition, a significant increase in transferrin saturation (TSAT), total iron binding capacity (TIBC) and total iron was observed in daprodustat groups compared with rhEPO groups in DD-CKD patients (p < 0.05). As for safety, the overall frequency of adverse events was similar between the daprodustat and rhEPO groups in DD-CKD patients (relative risk (RR) = 0.99, 95%CI = 0.92, 1.06, p = 0.76), and the trial sequential analysis (TSA) confirmed this result. But for NDD-CKD patients, the incidence of adverse events in the daprodustat groups was significantly higher than that of rhEPO groups (RR = 1.04, 95%CI = 1.01,1.07, p = 0.02), while the TSA corrected this result. No trend of increasing incidence of serious adverse events was found in all daprodustat treated patients, but the TSA could not confirm this result.

Conclusion: Although daprodustat was noninferior to rhEPO in correcting anemia in both NDD-CKD and DD-CKD patients, it seemed to have a better effect on optimizing iron metabolism in DD-CKD patients. Daprodustat may be a promising alternative for the treatment of anemia in patients with CKD. However, due to the lack of included studies, future researches are needed to further evaluate the therapeutic effect of daprodustat.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier CRD42021229636.

Anemia in Chronic Kidney Disease Patients: An Update

Chronic kidney disease (CKD) is one of the most common disabling diseases globally. The main etiopathology of CKD is attributed to progressive renal fibrosis secondary to recurrent renal insults. Anemia is a known complication in CKD patients, associated with higher hospitalization rates and increased mortality risk. CKD-associated anemia (CKD-AA) is either due to true iron deficiency and/or functional iron deficiency anemia. There is new emerging evidence about the effects of erythropoiesis stimulating agents in the treatment of CKD-AA and their role in reversing and preventing kidney fibrosis in the early stages of CKD. This effect potentially provides new scopes in the prevention and treatment of CKD-AA and in decreasing the progression of CKD and the associated long-term complications. Epidemiology, pathophysiology, and treatments of CKD-AA will be discussed.

Crosstalk between Acidosis and Iron Metabolism: Data from In Vivo Studies

Iron absorption requires an acidic environment that is generated by the activity of the proton pump gastric H(+)/K(+)ATPase (ATP4), expressed in gastric parietal cells. However, hepcidin, the iron regulatory peptide that inhibits iron absorption, unexpectedly upregulates ATP4 and increases gastric acidity. Thus, a concept of link between acidosis and alterations in iron metabolism, needs to be explored. We investigated this aspect in-vivo using experimental models of NH4Cl-induced acidosis and of an iron-rich diet. Under acidosis, gastric ATP4 was augmented. Serum hepcidin was induced and its mRNA level was increased in the liver but not in the stomach, a tissue where hepcidin is also expressed. mRNA and protein levels of intestinal DMT1(Divalent Metal Transporter 1) and ferroportin were downregulated. Serum iron level and transferrin saturation remained unchanged, but serum ferritin was significantly increased. Under iron-rich diet, the protein expression of ATP4A was increased and serum, hepatic and gastric hepcidin were all induced. Taken together, these results provide evidence of in-vivo relationship between iron metabolism and acidosis. For clinical importance, we speculate that metabolic acidosis may contribute in part to the pathologic elevation of serum hepcidin levels seen in patients with chronic kidney disease. The regulation of ATP4 by iron metabolism may also be of interest for patients with hemochromatosis.

Hypoxia-inducible factor-prolyl hydroxylase inhibitors for renal anemia in chronic kidney disease: Advantages and disadvantages

Anemia is a common feature and complication of chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) and recombinant human erythropoietin have been used widely in renal anemia treatment. Recently, hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PHIs) that may improve the treatment of renal anemia patients were launched. Previous studies indicated that HIF-PHIs may decrease hepcidin levels and modulate iron metabolism, thereby increasing total iron-binding capacity and reducing the need for iron supplementation. Furthermore, HIF-PHIs can reduce inflammation and oxidative stress in CKD. Recombinant erythropoietin has become a routine treatment for patients with CKD and end-stage renal disease with relatively few adverse effects. However, higher doses of recombinant erythropoietin have been demonstrated to be an independent predictor of mortality in patients under hemodialysis. Phase III clinical trials of HIF-PHIs in patients with anemia and dialysis-dependent CKD have shown their efficacy and safety in both non-dialysis and dialysis CKD patients. However, HIFα binds to specific hypoxia-response elements in the vascular endothelial growth factor or retinoic acid-related orphan receptor gamma t (RORγt) promoter, which may be involved in the progression of cancer, psoriasis, and rheumatoid arthritis. In this paper, we have summarized the mechanism, clinical application, and clinical trials of HIF-PHIs in the treatment of renal anemia and aimed to provide an overview of the new drugs in clinical practice, as well as reconsider the advantages and disadvantages of HIF-PHIs and ESAs. Presently, there are not enough clinical studies examining the effects of long-term administration of HIF-PHIs. Therefore, further studies will be needed.

INFERR-Iron infusion in haemodialysis study: INtravenous iron polymaltose for First Nations Australian patients with high FERRitin levels on haemodialysis-a protocol for a prospective open-label blinded endpoint randomised controlled trial

Background

The effectiveness of erythropoiesis-stimulating agents, which are the main stay of managing anaemia of chronic kidney disease (CKD), is largely dependent on adequate body iron stores. The iron stores are determined by the levels of serum ferritin concentration and transferrin saturation. These two surrogate markers of iron stores are used to guide iron replacement therapy. Most Aboriginal and/or Torres Islander Australians of the Northern Territory (herein respectfully referred to as First Nations Australians) with end-stage kidney disease have ferritin levels higher than current guideline recommendations for iron therapy. There is no clear evidence to guide safe and effective treatment with iron in these patients. We aim to assess the impact of intravenous iron treatment on all-cause death and hospitalisation with a principal diagnosis of all-cause infection in First Nations patients on haemodialysis with anaemia, high ferritin levels and low transferrin saturation

Methods

In a prospective open-label blinded endpoint randomised controlled trial, a total of 576 participants on maintenance haemodialysis with high ferritin (> 700 μg/L and ≤ 2000 μg/L) and low transferrin saturation (< 40%) from all the 7 renal units across the Northern Territory of Australia will be randomised 1:1 to receive intravenous iron polymaltose 400 mg once monthly (200 mg during 2 consecutive haemodialysis sessions) (Arm A) or no IV iron treatment (standard treatment) (Arm B). Rescue therapy will be administered when the ferritin levels fall below 700 μg/L or when clinically indicated. The primary outcome will be the differences between the two study arms in the risk of hospitalisation with all-cause infection or death. An economic analysis and several secondary and tertiary outcomes analyses will also be performed.

Discussion

The INFERR clinical trial will address significant uncertainty on the safety and efficacy of iron therapy in First Nations Australians with CKD with hyperferritinaemia and evidence of iron deficiency. This will hopefully lead to the development of evidence-based guidelines. It will also provide the opportunity to explore the causes of hyperferritinaemia in First Nations Australians from the Northern Territory.

Trial registration

This trial is registered with The Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000705987. Registered 29 June 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05854-w.

Reduced hepcidin expression enhances iron overload in patients with HbE/β-thalassemia: Α comparative cross-sectional study

Iron homeostasis is regulated by hepcidin (HEPC) that controls the dietary iron absorption and iron recycling. HEPC deficiency contributes to iron overload in β-thalassemia patients. The present study aimed to investigate the correlation between HEPC concentration and serum iron status among hemoglobin E (HbE)/β-thalassemia patients and their parents (HbE trait and β-thalassemia trait) compared with healthy controls. This study is a comparative cross-sectional study in which iron profile and HEPC level were examined in 65 HbE/β-thalassemia patients (pretransfusion) and 65 parents at the Hospital Sultanah Nur Zahirah and in 130 students as healthy controls from Univesiti Sultan Zainal Abidin, Terengganu, Malaysia. Furthermore, six samples from each group (HbE/β-thalassemia patients, parents and healthy controls) were randomly selected for gene expression analysis of HEPC and ferroportin1 (FPN1) using reverse transcription quantitative PCR. The results demonstrated that serum HEPC level were significantly decreased in HbE/β-thalassemia patients and their parents (P<0.001) compared with healthy controls. In addition, the gene expression analysis showed a dramatically downregulated HEPC in HbE/β-thalassemia patients and their parents (P=0.001) compared with healthy controls. However, there was a marked upregulation of FPN1 in HbE/β-thalassemia patients and their parents (P=0.001) compared with healthy controls. Iron profiling results revealed a significantly increased serum ferritin in HbE/β-thalassemia patients and their parents compared with healthy controls (P<0.001). In summary, the present study demonstrated that HEPC expression level and serum level were significantly decreased in HbE/β-thalassemia patients and their parents, which was combined with a marked increased FPN1 expression level and serum ferritin level compared with healthy volunteers. These findings supported the hypothesis that downregulated HEPC could lose its function as a negative regulator of FPN1, resulting in iron overload in HbE/β-thalassemia patients. Subsequently, assessing HEPC and FPN1 gene expression may be a useful tool to determine the risk of iron toxicity in patients with HbE/β-thalassemia and their parents, and could therefore be considered as a therapeutic target in the management of iron burden in these patients.

Safety and Efficacy of Roxadustat for Anemia in Patients With Chronic Kidney Disease: A Meta-Analysis and Trial Sequential Analysis

Background: Roxadustat, a hypoxia-inducible factor prolyl-hydroxylase inhibitor (HIF-PHI), has been used to treat anemia in patients with chronic kidney disease (CKD). However, its safety and efficacy remain controversial.

Methods: The PubMed, EMBASE, Science Citation Index, Cochrane Central Register of Controlled Trials, and Clinical Trial Registries databases were searched for relevant studies published up to April 2021. We identified randomized controlled trials (RCTs) comparing roxadustat with placebo or erythropoiesis-stimulating agents (ESAs) in anemia patients with CKD with or without dialysis.

Results: Eleven studies including 6,631 patients met the inclusion criteria. In non-dialysis-dependent (NDD-) and dialysis-dependent (DD-) CKD patients, the total adverse events were not significantly different between the roxadustat and control (placebo for NDD-CKD patients and ESA for DD-CKD patients) groups [relative risk (RR) = 1.02, 95% confidence interval (CI) = 1.00, 1.04, P = 0.08, and RR = 1.22, 95% CI = 0.91, 1.64, P = 0.18, respectively], and the trial sequential analysis (TSA) confirmed the result in the NDD-CKD groups. No significant differences in hyperkalemia and infection incidences were found between roxadustat and placebo in the DD-CKD groups. The pooled results showed that roxadustat significantly increased the hemoglobin response rate compared with placebo in the NDD-CKD group and had an effect similar to that of ESA in the DD-CKD group. However, iron metabolism parameters did not seem to be obviously optimized by roxadustat.

Conclusion: Roxadustat can be safely used in CKD patients. Oral roxadustat was more effective than placebo as a therapy for anemia in NDD-CKD patients and non-inferior to ESA in correcting anemia in DD-CKD patients. However, additional clinical trials are still needed to further prove whether roxadustat can optimize iron metabolism.

Оxidative stress and endogenous intoxication in cancer patients

In the blood serum of 93 patients with various localities of the malignant process, the content of nitric oxide (NO), indicators of lipid peroxidation (POL): superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione in red blood cells were determined. 9 patients with ovarian cancer were examined during chemotherapy (6 courses), 40 patients with colon cancer, previously operated, were with malignant liver damage. In 39 patients with anemia, NO indicators were compared with the level of interleukin 6 (IL-6) and hepcidin-25 (GP-25). As a control, 60 practically healthy individuals were examined. It was shown that the NO content was significantly reduced in 69.7% of patients, regardless of the location of the primary tumor. There was a gradual increase in the NO content before each course of chemotherapy. A high concentration of NO (more than 22 µM) was detected in 22 patients with functional iron deficiency (FJ) against the background of anemia of chronic diseases (AHZ), which was accompanied by hyperexpression of IL-6 (27.0±10.5 pg/ml) and GP-25 (25.2±7.1 ng/ml). In contrast, the lowest NO values (less than 22 µM) were observed in 17 patients with IDA. There is no doubt that there is a certain relationship between the development of oxidative stress with the accumulation of highly toxic lipoperoxidation products that affect the overall homeostasis of the body, and the development of anemic syndrome.

Hepcidin and GDF-15 are potential biomarkers of iron deficiency anaemia in chronic kidney disease patients in South Africa

BACKGROUND

Anaemia is a common presenting feature among patients with chronic kidney disease (CKD) and it is associated with poor clinical outcomes and quality of life. It is not clear if growth differentiation factor-15 (GDF-15) or hepcidin are useful as early markers of iron deficiency anaemia (IDA) among non-dialysis CKD patients. We therefore evaluated the diagnostic validity of GDF-15 and hepcidin as biomarkers of IDA among non-dialysis CKD patients in Johannesburg, South Africa.

METHOD

An analytic cross-sectional study was conducted among non-dialysis CKD patients (n = 312) and apparently healthy controls (n = 184) from June to December 2016 at an Academic Hospital, in Johannesburg, South Africa. An interviewer administered proforma was used to obtain the socio-biological and clinical characteristics of the participants. Serum levels of GDF-15 and hepcidin were determined. Predictive logistic regression models were built and post estimation receiver operator characteristics were determined to evaluate diagnostic validity of hepcidin and GDF-15 for absolute and functional iron deficiency anaemia.

RESULTS

About half (50.6%) of the participants were female while the participants' mean age was 49.7 ± 15.8 years. The predictive value of diagnosing absolute IDA among CKD patients using GDF-15 was 74.02% (95% CI: 67.62-80.42%) while the predictive value of diagnosing functional IDA among CKD patients using hepcidin was 70.1% (95% CI: 62.79-77.49%).There was a weak negative correlation between hepcidin levels and GFR (r = - 0.19, p = 0.04) in anaemic CKD patients, and between serum GDF-15 and haemoglobin (r = - 0.34, p = 0.001). Serum ferritin (β = 0.00389, P-value< 0.001), was a predictor of log hepcidin. MCHC (β = - 0.0220, P-value 0.005) and CKD stage (β = 0.4761, P-value < 0.001), race (β = 0.3429, P-value = 0.018) were predictors of log GDF-15. Both GDF-15 (adj OR: 1.0003, 95%CI: 1.0001-1.0005, P = 0.017) and hepcidin (adj OR: 1.003, 95%CI: 1.0004-1.0055, P = 0.023) were associated with iron deficiency anaemia after multiple linear regression modelling.

CONCLUSION

Serum GDF-15 is a potential biomarker of absolute IDA, while hepcidin levels can predict functional IDA among CKD patients.

A Novel Choice to Correct Inflammation-Induced Anemia in CKD: Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor Roxadustat

Anemia is a complication of chronic kidney disease (CKD), primarily due to insufficient secretion of erythropoietin (EPO) by the kidney. Erythropoiesis-stimulating agents (ESAs) are used to treat anemia associated with chronic kidney disease. A poor response to ESAs has been associated with inflammation. Inflammation can affect erythrocytes and its production in many ways, but mainly through the inflammatory cytokine IL-6 to stimulate the synthesis of hepcidin in the liver. Hepcidin causes iron insufficiency, which causes erythrocytes to fail to mature normally. In addition, inhibition of bone marrow erythroid precursor cells by inflammatory cytokines such as IL-1 and TNF-α also affects bone marrow hematopoiesis. These cytokines are also important factors leading to EPO resistance. Roxadustat is a new drug for the treatment of renal anemia. In addition to promoting the production of EPO, clinical trials have shown that it can significantly reduce hepcidin and can potentially be used for the treatment of inflammation-induced anemia in CKD.

Hepcidin, an overview of biochemical and clinical properties

Hepcidin is a peptide hormone which helps in regulating iron homeostasis in the human body. Iron obtained from daily diet is passed through the intestinal enterocyte apical membrane via divalent metal transporter 1 (DMT1), which is either stored as ferritin or moved into the plasma by hepcidin-ferroportin (Fpn) as an exporter. Hepcidin (hepatic bactericidal protein) is a cysteine rich peptide, was initially identified as a urinary antimicrobial peptide. It contains 25 amino acids and four disulfide bridges. It has significant role in regulation of iron in the body. Stimulation of iron in plasma and further its storage is linked with the production of hepcidin. This enhancement of iron hampers the absorption of iron from the diet. The cause of hereditary recessive anemia also known as Iron-refractory iron deficiency anemia (IRIDA) is characterized by increased hepcidin production due to a gene mutation in the suppressor matriptase-2/TMPRSS6. During infection, hepcidin plays a defensive role against various infections by depleting the extracellular iron from the body. Moreover, hepcidin lowers the concentrations of iron from the duodenal enterocytes, macrophages and also decrease its transport across the placenta.This review highlights the significant role of hepcidin in the iron homeostasis and as an antimicrobial agent.

Inflammation and Erythropoiesis-Stimulating Agent Response in Hemodialysis Patients: A Self-matched Longitudinal Study of Anemia Management in the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Rationale & Objective

Previous studies of inflammation and anemia management in hemodialysis (HD) patients may be biased due to patient differences. We used a self-matched longitudinal design to test whether new inflammation, defined as an acute increase in C-reactive protein (CRP) level, reduces hemoglobin response to erythropoiesis-stimulating agent (ESA) treatment.

Study Design

Self-matched longitudinal design.

Setting & Participants

3,568 new inflammation events, defined as CRP level > 10 mg/L following a 3-month period with CRP level ≤ 5 mg/L, were identified from 12,389 HD patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 4 to 6 (2009-2018) in 10 countries in which CRP is routinely measured.

Predictor

“After” (vs “before”) observing a high CRP level.

Outcomes

Within-patient changes in hemoglobin level, ESA dose, and ESA hyporesponsiveness (hemoglobin < 10 g/dL and ESA dose > 6,000 [Japan] or >8,000 [Europe] U/wk).

Analytical Approach

Linear mixed models and modified Poisson regression.

Results

Comparing before with after periods, mean hemoglobin level decreased from 11.2 to 10.9 g/dL (adjusted mean change, −0.26 g/dL), while mean ESA dose increased from 6,320 to 6,960 U/wk (adjusted relative change, 8.4%). The prevalence of ESA hyporesponsiveness increased from 7.6% to 12.3%. Both the unadjusted and adjusted prevalence ratios of ESA hyporesponsiveness were 1.68 (95% CI, 1.48-1.91). These associations were consistent in sensitivity analyses varying CRP thresholds and were stronger when the CRP level increase was sustained over the 3-month after period.

Limitations

Residual confounding by unmeasured time-varying risk factors for ESA hyporesponsiveness.

Conclusions

In the 3 months after HD patients experienced an increase in CRP levels, hemoglobin levels declined quickly, ESA doses increased, and the prevalence of ESA hyporesponsiveness increased appreciably. Routine CRP measurement could identify inflammation as a cause of worsened anemia. In turn, these findings speak to a potentially important role for anemia therapies that are less susceptible to the effects of inflammation.

Association of Hepcidin With Anemia Parameters in Incident Dialysis Patients: Differences Between Dialysis Modalities

Hepcidin's relationships with other variables are unclear. We evaluated associations of serum hepcidin with clinical parameters in ESRD patients. Ninety-nine incident dialysis patients, including 57 on peritoneal dialysis (PD) and 42 on HD, were prospectively followed for 6 months. Serum hepcidin levels significantly increased during initial 6 months of dialysis. In the multivariate regression model, independent predictors of serum hepcidin levels in ESRD patients before maintenance dialysis were interleukin-6, ferritin, phosphate, iron, and aspartate transaminase. Six months after initiating dialysis, serum hepcidin levels were independently predicted by ferritin, total iron binding capacity (TIBC), and aspartate transaminase in all patients, whereas by ferritin and TIBC in PD patients, and ferritin, TIBC, and 24-h urine volume in HD patients. Serum hepcidin levels are differentially associated with anemia parameters in PD compared with HD patients. Urine volume was an independent predictor of hepcidin levels in early HD patients.

[Expression and influencing factors of hepcidin in classical paroxysmal nocturnal hemoglobinuria]

目的

研究铁调素在经典型阵发性睡眠性血红蛋白尿症（PNH）患者血清中的表达及其影响因素。

方法

以2016年3月至2017年3月36例经典型PNH患者为研究对象，采用ELISA方法检测血清铁调素水平，并结合患者铁稳态状况和临床资料，分析经典型PNH患者血清铁调素水平与血清铁蛋白（SF）、可溶性转铁蛋白受体、C反应蛋白、EPO、网织红细胞绝对值、网织红细胞血红蛋白等血液学参数的相关性。

结果

36例经典型PNH患者血清铁调素水平为32.03（23.11，118.48）µg/L，明显低于正常对照组的181.42（106.80，250.53）µg/L（z=−5.107，P<0.001）。其中，铁蛋白正常经典型PNH患者血清铁调素水平为56.41（44.60，95.06）µg/L，经典型PNH伴缺铁组血清铁调素水平为23.75（21.77，30.35）µg/L，均低于正常对照组；而经典型PNH伴铁蛋白升高组血清铁调素水平为336.19（304.19，375.08）µg/L，高于正常对照组、铁蛋白正常经典型PNH组及经典型PNH伴缺铁组。多重线性回归分析显示SF、转铁蛋白饱和度和血清白蛋白水平是经典型PNH患者血清铁调素水平的独立影响因素。

结论

经典型PNH患者血清铁调素水平减低，其表达主要受铁代谢因素影响。

Peptide based therapeutics and their use for the treatment of neurodegenerative and other diseases

Bioactive peptides are actively involved in different biological functions and importantly contribute to human health, and the use of peptides as therapeutics has a long successful history in disease management. A number of peptides have wide-ranging therapeutic effects, such as antioxidant, antimicrobial, and antithrombotic effects. Neurodegenerative diseases are typically caused by abnormal aggregations of proteins or peptides, and the depositions of these aggregates in or on neurons, disrupt signaling and eventually kill neurons. During recent years, research on short peptides has advanced tremendously. This review offers a brief introduction to peptide based therapeutics and their application in disease management and provides an overview of peptide vaccines, and toxicity related issues. In addition, the importance of peptides in the management of different neurodegenerative diseases and their therapeutic applications is discussed. The present review provides an understanding of peptides and their applications for the management of different diseases, but with focus on neurodegenerative diseases. The role of peptides as anti-cancer, antimicrobial and antidiabetic agents has also been discussed.

Hepcidin serum levels and resistance to recombinant human erythropoietin therapy in hemodialysis patients

OBJECTIVE

The aim of this study was to analyze the factors that are associated with the response to erythropoiesis-stimulating agents (ESAs) and its association with hospitalization and mortality rates; to evaluate the serum hepcidin level and its associations with iron profile, inflammatory markers, ESA responsiveness, and mortality; and to determine independent factors affecting ERI and hepcidin.

MATERIALS AND METHODS

To evaluate a dose-response effect of ESAs we used the erythropoietin resistance index (ERI). Patients were stratified in two groups: nonresponders and responders (ERI>15, n=20, and ERI ≤15U/kg/week/g per 100mL, n=153, respectively). Hematological data, hepcidin levels, iron parameters, inflammatory markers, hospitalization and mortality rates were compared between the groups. Multiple regression analysis was used to determine independent factors affecting ERI and hepcidin.

RESULTS

C-reactive protein (CRP) (β=0.078, P=0.007), albumin (β=-0.436, P=0.004), body mass index (β=-0.374, P<0.001), and hospitalization rate per year (β=3.017, P<0.001) were found to be significant determinants of ERI in maintenance hemodialysis (MHD) patients. Inadequate dialysis was associated with higher ERI. Patients with concomitant oncological diseases had higher ERI (31.2±12.4 vs 9.7±8.1U/kg/week/g per 100mL, P=0.002). The hepcidin level was 158.51±162.57 and 120.65±67.28ng/mL in nonresponders and responders, respectively (P=0.33). Hepcidin correlated directly with ERI, dose of ESAs, ferritin and inversely with Hb, transferrin saturation, and albumin. ERI (β=4.869, P=0.002) and ferritin (β=0.242, P=0.003) were found to be significant determinants of hepcidin in MHD patients. The hospitalization rate per year was 2.35±1.8 and 1.04±1.04 in nonresponders and responders, respectively (P=0.011). The mean length of one hospitalization was 25.12±21.26 and 10.82±17.25 days, respectively (P=0.012). Death occurred in 30% of the patients from the responders' group and in 50% from the nonresponders' group (P=0.289). The mean hepcidin concentration of patients who died was 141.9±129.62ng/mL and who survived, 132.98±109.27ng/mL (P=0.797).

CONCLUSIONS

CRP, albumin, BMI, and hospitalization rate per year were found to be significant determinants of ERI in MHD patients. Inadequate dialysis was associated with higher epoetin requirements. There were no difference in patient mortality by ERI, but a significant difference in hospitalization rates and mean length of one hospitalization was revealed. A significant positive relation between hepcidin and ERI was revealed. ERI and ferritin were found to be significant determinants of hepcidin in MHD patients. Hepcidin was not related to mortality.

Assessing the Association between Serum Ferritin, Transferrin Saturation, and C-Reactive Protein in Northern Territory Indigenous Australian Patients with High Serum Ferritin on Maintenance Haemodialysis

Objective. To determine the significance of high serum ferritin observed in Indigenous Australian patients on maintenance haemodialysis in the Northern Territory, we assessed the relationship between ferritin and transferrin saturation (TSAT) as measures of iron status and ferritin and C-reactive protein (CRP) as markers of inflammation. Methods. We performed a retrospective cohort analysis of data from adult patients (≥18 years) on maintenance haemodialysis (>3 months) from 2004 to 2011. Results. There were 1568 patients. The mean age was 53.9 (11.9) years. 1244 (79.3%) were Indigenous. 44.2% (n = 693) were male. Indigenous patients were younger (mean age [52.3 (11.1) versus 57.4 (15.2), p < 0.001]) and had higher CRP [14.7 mg/l (7–35) versus 5.9 mg/l (1.9–17.5), p < 0.001], higher median serum ferritin [1069 µg/l (668–1522) versus 794.9 µg/l (558.5–1252.0), p < 0.001], but similar transferrin saturation [26% (19–37) versus 28% (20–38), p = 0.516]. We observed a small positive correlation between ferritin and TSAT (r² = 0.11, p < 0.001), no correlation between ferritin and CRP (r² = 0.001, p < 0.001), and positive association between high serum ferritin and TSAT (p < 0.001), Indigenous ethnicity (p < 0.001), urea reduction ratio (p = 0.001), and gender (p < 0.001) after adjustment in mixed regression analysis. Conclusion. Serum ferritin and TSAT may inadequately reflect iron status in this population. The high ferritin was poorly explained by inflammation.

Hepcidin inhibits Smad3 phosphorylation in hepatic stellate cells by impeding ferroportin-mediated regulation of Akt

Hepatic stellate cell (HSC) activation on liver injury facilitates fibrosis. Hepatokines affecting HSCs are largely unknown. Here we show that hepcidin inhibits HSC activation and ameliorates liver fibrosis. We observe that hepcidin levels are inversely correlated with exacerbation of fibrosis in patients, and also confirm the relationship in animal models. Adenoviral delivery of hepcidin to mice attenuates liver fibrosis induced by CCl₄ treatment or bile duct ligation. In cell-based assays, either hepcidin from hepatocytes or exogenous hepcidin suppresses HSC activation by inhibiting TGFβ1-mediated Smad3 phosphorylation via Akt. In activated HSCs, ferroportin is upregulated, which can be prevented by hepcidin treatment. Similarly, ferroportin knockdown in HSCs prohibits TGFβ1-inducible Smad3 phosphorylation and increases Akt phosphorylation, whereas ferroportin over-expression has the opposite effect. HSC-specific ferroportin deletion also ameliorates liver fibrosis. In summary, hepcidin suppresses liver fibrosis by impeding TGFβ1-induced Smad3 phosphorylation in HSCs, which depends on Akt activated by a deficiency of ferroportin.

The peptide hormone hepcidin is released from hepatocytes and regulates iron homoeostasis. Here, the authors show that hepcidin also regulates the activation of hepatic stellate cells (HSCs) in mouse models of liver fibrosis by reducing ferroportin expression and inhibiting the HSC response to TGFβ.

Hepcidin Response to Iron Therapy in Patients with Non-Dialysis Dependent CKD: An Analysis of the FIND-CKD Trial

Hepcidin is the key regulator of iron homeostasis but data are limited regarding its temporal response to iron therapy, and response to intravenous versus oral iron. In the 56-week, open-label, multicenter, prospective, randomized FIND-CKD study, 626 anemic patients with non-dialysis dependent chronic kidney disease (ND-CKD) and iron deficiency not receiving an erythropoiesis stimulating agent were randomized (1:1:2) to intravenous ferric carboxymaltose (FCM), targeting higher (400-600μg/L) or lower (100-200μg/L) ferritin, or to oral iron. Serum hepcidin levels were measured centrally in a subset of 61 patients. Mean (SD) baseline hepcidin level was 4.0(3.5), 7.3(6.4) and 6.5(5.6) ng/mL in the high ferritin FCM (n = 17), low ferritin FCM (n = 16) and oral iron group (n = 28). The mean (SD) endpoint value (i.e. the last post-baseline value) was 26.0(9.1),15.7(7.7) and 16.3(11.0) ng/mL, respectively. The increase in hepcidin from baseline was significantly smaller with low ferritin FCM or oral iron vs high ferritin FCM at all time points up to week 52. Significant correlations were found between absolute hepcidin and ferritin values (r = 0.65, p<0.001) and between final post-baseline increases in both parameters (r = 0.70, p<0.001). The increase in hepcidin levels over the 12-month study generally mirrored the cumulative iron dose in each group. Hepcidin and transferrin saturation (TSAT) absolute values showed no correlation, although there was an association between final post-baseline increases (r = 0.42, p<0.001). Absolute values (r = 0.36, p = 0.004) and final post-baseline increases of hepcidin and hemoglobin (p = 0.30, p = 0.030) correlated weakly. Baseline hepcidin levels were not predictive of a hematopoietic response to iron therapy. In conclusion, hepcidin levels rose in response to either intravenous or oral iron therapy, but the speed and extent of the rise was greatest with intravenous iron targeting a higher ferritin level. However neither the baseline level nor the change in hepcidin was able to predict response to therapy in this cohort.

The Different Association between Serum Ferritin and Mortality in Hemodialysis and Peritoneal Dialysis Patients Using Japanese Nationwide Dialysis Registry

BACKGROUND/AIMS

Monitoring of serum ferritin levels is widely recommended in the management of anemia among patients on dialysis. However, associations between serum ferritin and mortality are unclear and there have been no investigations among patients undergoing peritoneal dialysis (PD).

METHODS

Baseline data of 191,902 patients on dialysis (age, 65 ± 13 years; male, 61.1%; median dialysis duration, 62 months) were extracted from a nationwide dialysis registry in Japan at the end of 2007. Outcomes, such as one-year mortality, were then evaluated using the registry at the end of 2008.

RESULTS

Within one year, a total of 15,284 (8.0%) patients had died, including 6,210 (3.2%) cardiovascular and 2,707 (1.4%) infection-related causes. Higher baseline serum ferritin levels were associated with higher mortality rates among patients undergoing hemodialysis (HD). In contrast, there were no clear associations between serum ferritin levels and mortality among PD patients. Multivariate Cox regression analysis of HD patients showed that those in the highest serum ferritin decile group had higher rates of all-cause and cardiovascular mortality than those in the lowest decile group (hazard ratio [HR], 1.54; 95% confidence interval [CI], 1.31-1.81 and HR, 1.44; 95% CI, 1.13-1.84, respectively), whereas associations with infection-related mortality became non-significant (HR, 1.14; 95% CI, 0.79-1.65).

CONCLUSIONS

Using Japanese nationwide dialysis registry, higher serum ferritin values were associated with mortality not in PD patients but in HD patients.

Methoxy polyethylene glycol-epoetin beta for the treatment of anemia associated with chronic renal failure

Since more than two decades erythropoiesis-stimulating agents are the main pillar for treatment of anemia associated with chronic kidney disease. Methoxy polyethylene glycol-epoetin beta (MPG-EPO), also called continuous erythropoietin receptor activator, is the longest acting erythropoiesis-stimulating agent currently available. MPG-EPO is characterized by an elimination half-life of approximately 137 h and offers extended dosing intervals up to 4 weeks. Numerous phase I/II studies and a comprehensive clinical phase III program demonstrated the feasibility of MPG-EPO therapy for anemia correction and maintenance of stable hemoglobin levels in adult chronic kidney disease patients. Due to patent disputes MPG-EPO was only available outside the US market so far. In view of a prevailing US market introduction, this review focuses on efficacy and safety data from pivotal trials, summarizes recent clinical research and finally tries to substantiate potential benefits associated with the use of this anti-anemic drug.

Urinary Hepcidin Levels in Iron-Deficient and Iron-Supplemented Piglets Correlate with Hepcidin Hepatic mRNA and Serum Levels and with Body Iron Status

Among livestock, domestic pig (Sus scrofa) is a species, in which iron metabolism has been most intensively examined during last decade. The obvious reason for studying the regulation of iron homeostasis especially in young pigs is neonatal iron deficiency anemia commonly occurring in these animals. Moreover, supplementation of essentially all commercially reared piglets with iron entails a need for monitoring the efficacy of this routine practice followed in the swine industry for several decades. Since the discovery of hepcidin many studies confirmed its role as key regulator of iron metabolism and pointed out the assessment of its concentrations in biological fluids as diagnostic tool for iron-related disorder. Here we demonstrate that urine hepcidin-25 levels measured by a combination of weak cation exchange chromatography and time-of-flight mass spectrometry (WCX-TOF MS) are highly correlated with mRNA hepcidin expression in the liver and plasma hepcidin-25 concentrations in anemic and iron-supplemented 28-day old piglets. We also found a high correlation between urine hepcidin level and hepatic non-heme iron content. Our results show that similarly to previously described transgenic mouse models of iron disorders, young pigs constitute a convenient animal model to explore accuracy and relationship between indicators for assessing systemic iron status.

Considerations and challenges in defining optimal iron utilization in hemodialysis

Trials raising concerns about erythropoiesis-stimulating agents, revisions to their labeling, and changes to practice guidelines and dialysis payment systems have provided strong stimuli to decrease erythropoiesis-stimulating agent use and increase intravenous iron administration in recent years. These factors have been associated with a rise in iron utilization, particularly among hemodialysis patients, and an unprecedented increase in serum ferritin concentrations. The mean serum ferritin concentration among United States dialysis patients in 2013 exceeded 800 ng/ml, with 18% of patients exceeding 1200 ng/ml. Although these changes are broad based, the wisdom of these practices is uncertain. Herein, we examine influences on and trends in intravenous iron utilization and assess the clinical trial, epidemiologic, and experimental evidence relevant to its safety and efficacy in the setting of maintenance dialysis. These data suggest a potential for harm from increasing use of parenteral iron in dialysis-dependent patients. In the absence of well powered, randomized clinical trials, available evidence will remain inadequate for making reliable conclusions about the effect of a ubiquitous therapy on mortality or other outcomes of importance to dialysis patients. Nephrology stakeholders have an urgent obligation to initiate well designed investigations of intravenous iron in order to ensure the safety of the dialysis population.

Hepcidin and risk of anemia in CKD: a cross-sectional and longitudinal analysis in the CKiD cohort

BACKGROUND

Hepcidin, a key iron regulatory protein, is elevated in patients with chronic kidney disease (CKD). Its role in the development and progression of the anemia of CKD in children remains poorly defined.

METHODS

Cross-sectional and longitudinal study in children aged 1-16 years with stage 2-4 CKD in the Chronic Kidney Disease in Children (CKiD) cohort (n = 133) with hepcidin measured at baseline and hemoglobin (HGB) measured annually at follow-up. Anemia was defined as HGB <5th percentile for age/sex OR treatment with an erythropoiesis-stimulating agent (ESA).

RESULTS

Hepcidin levels correlated negatively with glomerular filtration rate (GFR; r = -0.22, p = 0.01) and positively with ferritin (r = 0.67, p < 0.001). At the lower end of the GFR spectrum at baseline (10th percentile, 27.5 mL/min/1.73 m(2)), higher hepcidin was associated with a 0.87 g/dL decrease in HGB during follow-up (95 % CI -1.69, -0.05 g/dL, p = 0.038). At higher GFR percentiles there was no significant association between baseline hepcidin and HGB during follow-up. Among 90 non-anemic subjects at baseline, 23.3 % developed incident anemia. In subjects with GFR  ≤  the median, a higher hepcidin level was associated with an increased risk of incident anemia (at the 10th percentile GFR, HR 3.471, 95 % CI 1.228, 9.810, p = 0.019; at the 25th percentile GFR, HR 2.641, 95 % CI 1.213, 5.750, p = 0.014; at the 50th percentile GFR, HR 1.953, 95 % CI 1.011, 3.772, p = 0.046). Among subjects with GFR at the 75th percentile or above, incrementally higher baseline hepcidin was not associated with increased anemia risk.

CONCLUSIONS

Higher hepcidin levels are associated with a decreased HGB and an increased risk of incident anemia, and this association is most significant among subjects with lower GFR.

Hypersensitivity from intravenous iron products

In the last several years, intravenous therapy with iron products has been more widely used. Although it has been a standard procedure in dialysis-associated anemia since the early 1990s, its use is expanding to a host of conditions associated with iron deficiency, especially young women with heavy uterine bleeding and pregnancy. Free iron is associated with unacceptable high toxicity inducing severe, hemodynamically significant symptoms. Subsequently, formulations that contain the iron as an iron carbohydrate nanoparticle have been designed. With newer formulations, including low-molecular-weight iron dextran, iron sucrose, ferric gluconate, ferumoxytol, iron isomaltoside, and ferric carboxymaltose, serious adverse events are rare.

Update on intravenous iron choices

PURPOSE OF REVIEW

Iron deficiency is a major factor in the prevalence and severity of anemia in patients with chronic kidney disease (CKD). We review the pathophysiology impairing normal intestinal iron absorption in CKD and compare the characteristics of newer intravenous (i.v.) iron agents to the longstanding i.v. iron products in the market.

RECENT FINDINGS

The newer iron products, ferumoxytol, ferric carboxymaltose, and iron isomaltoside, more avidly bind iron, minimizing the release of labile iron during infusions, thus permitting large dose infusions. These irons also have more complex carbohydrate shells than their predecessors, which may also diminish reactions. Newer agents can be routinely administered at higher single doses, in as little as 15 min, with an acceptable safety profile.

SUMMARY

Newer i.v. iron products permit the rapid, and sometimes complete, repletion of iron-deficient patients with a single dose. However, further studies examining the long-term risks and benefits of i.v. iron repletion are needed.

Cumulative iron dose and resistance to erythropoietin

INTRODUCTION

Optimizing anemia treatment in hemodialysis (HD) patients remains a priority worldwide as it has significant health and financial implications. Our aim was to evaluate in a large cohort of chronic HD patients in Fresenius Medical Care centers in Spain the value of cumulative iron (Fe) dose monitoring for the management of iron therapy in erythropoiesis-stimulating agent (ESA)-treated patients, and the relationship between cumulative iron dose and risk of hospitalization.

METHODS

Demographic, clinical and laboratory parameters from EuCliD(®) (European Clinical Dialysis Database) on 3,591 patients were recorded including ESA dose (UI/kg/week), erythropoietin resistance index (ERI) [U.I weekly/kg/gr hemoglobin (Hb)] and hospitalizations. Moreover the cumulative Fe dose (mg/kg of bodyweight) administered over the last 2 years was calculated. Univariate and multivariate analyses were performed to identify the main predictors of ESA resistance and risk of hospitalization. Patients belonging to the 4th quartile of ERI were defined as hypo-responders.

RESULTS

The 2-year iron cumulative dose was significantly higher in the 4th quartile of ERI. In hypo-responders, 2-year cumulative iron dose was the only iron marker associated with ESA resistance. At case-mix adjusted multivariate analysis, 2-year iron cumulative dose was an independent predictor of hospitalization risk.

DISCUSSION

In ESA-treated patients cumulative Fe dose could be a useful tool to monitor the appropriateness of Fe therapy and to prevent iron overload. To establish whether the associations between cumulative iron dose, ERI and hospitalization risk are causal or attributable to selection bias by indication, clinical trials are necessary.

Pentoxifylline does not alter the concentration of hepcidin in chronic kidney disease patients undergoing hemodialysis

INTRODUCTION

Anemia is a frequent condition in patients with chronic kidney disease due to a reduction in the production of erythropoietin. Patients with inflammation respond less well to treatment with erythropoietin, possibly because the increased production of hepcidin reduces the availability of iron for hematopoiesis. Some studies suggest that pentoxifylline has anti-inflammatory properties and could be used as adjuvant therapy in the treatment of anemia.

OBJECTIVE

The aim of this study was to analyze the effect of pentoxifylline on serum hepcidin in chronic hemodialysis patients with inflammation.

METHODS

71 adult patients on hemodialysis with C-reactive protein (CRP) ≥0.5 mg/dl in screening tests; patients were randomized to the treatment group (oral pentoxifylline 400 mg/thrice-weekly) or the control group for 3 months follow-up.

RESULTS

During the study, a decrease in hemoglobin, transferrin saturation, and hepcidin was observed in both groups. However, these reductions were related to the time and not to the drug. There was no difference in the concentrations of CRP, ferritin, and albumin over time in either group.

CONCLUSIONS

The use of this amount of pentoxifylline did not modify the serum levels of hepcidin in this population.

Inflammation, high ferritin, and erythropoietin resistance in indigenous maintenance hemodialysis patients from the Top End of Northern Australia

Use of erythropoiesis-stimulating agents (ESAs) has improved the management of anemia in patients on maintenance hemodialysis (MHD). Iron deficiency and inflammation cause ESAs resistance and are both common among indigenous people of Northern Australia. As part of quality assurance in our Renal Anaemia Management program, we observed that there was use of higher doses of ESAs and adjuvant iron therapy in our MHD patients. This study aimed to explore the relationship among iron studies, inflammation, ESA responsiveness, and ESAs and iron requirements in indigenous patients on MHD from the Top End of Northern Australia. We performed a retrospective cohort analysis of anemia management in a cohort of our patients on MHD. We extracted data for 178 indigenous and 19 non-indigenous patients from 1 March 2009 to 28 February 2010 from the Renal Anaemia Management database, which collects data prospectively in MHD patients. Ninety-nine percent of the whole sample had a ferritin level above the international guidelines threshold of >500 µg/L. Indigenous patients had higher ferritin (1534 ± 245.5 µg/L vs. 1013 ± 323.3 µg/L, P = 0.002). C-reactive protein (CRP) was high in 56.9% of the total cohort. One hundred percent of those with normal CRP had high ferritin (>500 µg/L). C-reactive protein was higher in indigenous than in non-indigenous patients. Erythropoiesis-stimulating agents hyporesponsiveness was higher in indigenous patients (P < 0.0001). There was no significant difference in ESAs hyporesponsiveness among different levels of CRP (P = 0.116), ferritin (P = 0.408), and transferrin saturation (P = 0.503). Indigenous patients required higher total iron dose (2820.30 [2000-4350] vs. 2336.12 [1912-2900], P = 0.02). There was no significant relationship between the high ferritin and CRP. In indigenous dialysis patients, iron therapy and ESAs use are higher. The high iron use is due to a lack of published evidence to guide the administration of iron in patients with high ferritin. The high ferritin and ESAs resistance could not be fully explained by inflammation and need further evaluation. Further studies are required to determine the safe use of iron and management of ESAs resistance in our hemodialysis population.

Serum hepcidin-25 and response to intravenous iron in patients with non-dialysis chronic kidney disease

BACKGROUND

Hepcidin-25 is an iron regulator which reduces iron absorption and promotes sequestration in the reticulo-endothelial system. We investigated hepcidin and traditional iron storage marker utility in predicting haemoglobin increment following bolus intravenous iron.

METHODS

The cohort included 129 consecutive non-dialysis chronic kidney disease patients that attended for intravenous iron over a 6-month period. Serum hepcidin-25 levels (determined by mass spectrometry) pre iron infusion and 6 weeks post were compared with ferritin and transferrin saturation in multivariate models.

RESULTS

Log10 ferritin [coefficient 0.559 (0.435-0.684) p < 0.001] and log10 high-sensitive C-reactive protein [coefficient 0.092 (0.000-0.184) p = 0.049] were significantly associated with baseline log10 hepcidin-25 levels. Log10 estimated glomerular filtration rate was the only independent determinant of pre-infusion haemoglobin [coefficient 1.37 (0.16-2.59) p = 0.027]. Log10 hepcidin-25 was an independent predictor of haemoglobin increment 6 weeks following iron infusion [coefficient -0.84 (-1.38 to -0.31) p = 0.002]. Ferritin, transferrin saturation and hepcidin had similar predictive utility for a 1 g/dl haemoglobin increase (c-statistics: 0.68, 0.70, 0.69).

CONCLUSIONS

Hepcidin is an iron sensor marker which predicts the magnitude of haemoglobin increment following protocolised intravenous iron infusion. Although displaying similar predictive performance to ferritin and transferrin saturation, hepcidin may also play a mechanistic role.

Hepcidin production in response to iron is controlled by monocyte-derived humoral factors

Hepcidin, which is mainly produced by the liver, is the key regulator in iron homeostasis. Hepcidin expression is up-regulated by iron loading in vivo, but the mechanism underlying this process is not completely understood. In the present study, we investigated the mechanism, following the hypothesis that hepcidin production in response to iron loading is regulated by extra-hepatic iron sensors. We measured serum hepcidin concentrations and iron indices in Wistar rats treated with saccharated ferric oxide (SFO). Human hepatoma-derived HepG2 cells were stimulated using SFO-administered rat sera, and co-cultured with rat spleen cells, human monocyte-derived THP-1 cells, or human monocytes with diferric transferrin (holo-Tf), and hepcidin concentrations in the conditioned media were measured. SFO elevated rat serum hepcidin concentrations. SFO-treated rat sera increased hepcidin production from HepG2 cells, and this induction correlated with serum hepcidin levels, but not with iron indices. Holo-Tf up-regulated hepcidin concentrations in media from HepG2 cells co-cultured with rat spleen cells, THP-1 cells, or human monocytes with or without cell-to-cell contacts, while holo-Tf did not up-regulate hepcidin from HepG2 cells alone. Our results suggest the existence of humoral factors capable of inducing hepcidin production that are secreted by extra-hepatic cells, such as reticuloendothelial monocytes, in response to iron.

Iron deficiency anaemia in chronic kidney disease

BACKGROUND

Iron Deficiency Anaemia (IDA) has been shown to be the most common cause of anaemia worldwide. It is accepted that people with chronic kidney disease (CKD) develop anaemia as their kidney function declines.

METHODS

To better understand IDA in CKD, it is necessary to appreciate the normal iron metabolism and utilisation of iron and how these processes can be disordered in patients with CKD. The problems related to infection / inflammation and oxidative stress are examined. Whilst National and international guidelines recommend specific tests for IDA, these and alternative tests are reviewed.

CONCLUSIONS

Whilst iron supplementation is necessary for CKD patients with IDA, iron metabolism and utilisation can be affected by factors such as infection or inflammation. Iron is essential element for all life, it can be toxic to cells through the process of oxidative stress. The recommended tests for IDA may be affected by factors such as infection and inflammation. Alternative tests are available, which may be a more accurate indicator of IDA as they are not affected by external factors.

Ferroportin in monocytes of hemodialysis patients and its associations with hepcidin, inflammation, markers of iron status and resistance to erythropoietin

PURPOSE

Disturbed iron homeostasis contributes to resistance to recombinant human erythropoietin (rHuEpo) in hemodialysis (HD) patients. Increased hepcidin, which downregulates the iron exporter ferroportin, has been incriminated. However, other factors also control ferroportin expression in mononuclear phagocyte system. Ferroportin in monocytes, as well as serum hepcidin, interleukin-6 (IL-6) and common markers of iron status were measured and correlations with rHuEpo resistance index (ERI) were evaluated.

METHODS

After a 4-week washout period from iron treatment, 34 HD patients and 20 healthy volunteers enrolled in the study. Ferroportin was assessed by means of western blotting, whereas hepcidin and IL-6 with enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin and transferrin saturation (TSAT) were also measured.

RESULTS

Ferroportin in monocytes of HD patients was decreased. Serum hepcidin and IL-6 were increased, whereas serum iron and TSAT were decreased. ERI was negatively correlated with ferroportin and all the markers of iron adequacy, but not with hepcidin.

CONCLUSION

Decreased ferroportin in monocytes of HD patients accompanies increased hepcidin, inflammation, decreased iron availability and is correlated with resistance to rHuEpo treatment.

Hepcidin levels predict nonresponsiveness to oral iron therapy in patients with iron deficiency anemia

Levels of hepcidin, a major regulator of iron homeostasis, may identify patients with iron deficiency anemia (IDA) who will not respond to oral iron therapy. In this study, IDA patients underwent a 14-day trial (run-in) course of ferrous sulfate therapy. Nonresponders (Hgb increase <1 g/dL with 67% compliance rate) were randomized to IV ferric carboxymaltose (FCM; two injections of 750 mg) or further oral iron for 14 days. Screening hepcidin levels were 38.4 versus 11.3 ng/mL, P = 0.0002 in nonresponders versus responders to a trial of oral iron. Hepcidin of > 20 ng/mL, showed sensitivity of 41.3%, specificity of 84.4%, and positive predictive value of 81.6% for predicting nonresponsiveness to oral iron. PPVs for ferritin> 30 ng/mL or transferrin saturation (TSAT)>15% were 59.2 and 55%, respectively. Negative predictive values for hepcidin, ferritin, and TSAT were 46.3, 22.7, and 19.7, respectively. FCM versus oral iron showed Hgb increases of ≥ 1 gm/dL in 65.3% versus 20.8% (P < 0.0001) and Hgb increases of 1.7 ± 1.3 versus 0.6 ± 0.9 g/dL (P = 0.0025), respectively. We conclude that hepcidin predicts nonresponsiveness to oral iron in patients with IDA and is superior to TSAT or ferritin for this purpose. Nonresponse to oral iron therapy does not rule out IDA, since two-thirds of patients subsequently responded to intravenous iron.

Understanding and exploiting hepcidin as an indicator of anemia due to chronic kidney disease

Hepcidin, produced by the liver, is the master regulator of iron balance. Serum hepcidin is increased by high iron stores, blocks intestinal iron absorption, and impairs storage iron release. Conversely, iron deficiency lowers hepcidin levels and enhances intestinal iron absorption and the release of storage iron. As with ferritin, hepcidin is an acute phase reactant. Consequently, inflammation increases hepcidin and leads to impaired iron absorption, lowers serum iron and transferrin saturation, and contributes to the anemia of chronic kidney disease (CKD). We review the physiology of iron absorption, its relationship to hepcidin and the transmembrane iron transporter ferroportin, the role of hepcidin in CKD related anemia, and the possible diagnostic implications and limitations of using hepcidin as a marker of iron status.