Hepcidin in Anemia and Inflammation in Chronic Kidney Disease

Functional iron deficiency anemia was associated with higher mortality in chronic kidney disease patients: the NHANES III follow-up study

Anemia, a common complication of chronic kidney disease (CKD), is associated with poor prognosis. However, it is not completely clear whether this association is caused by anemia per se or other comorbidities. Whether different types of iron deficiency anemia can predict the outcomes of CKD remains unclear. The dataset from NHANES III was analyzed and Cox multivariate regression models and propensity score matching (PSM) method were used to evaluate the effect of anemia on mortality. Of 4103 patients with CKD, 14.6% had anemia. Among those with anemia, 38.8% had absolute iron deficiency (AID), and 19.8% had functional iron deficiency (FID). During the median follow-up time of 13.8 years, 2964 deaths and 804 cardiovascular deaths were observed. Anemia was robustly associated with a high risk of all-cause mortality in CKD patients after adjusting covariates by two multivariate regression models (Model 1: HR = 1.485, 95%CI:1.340-1.647, p < 0.001; Model 2: HR = 1.391, 95%CI:1.250-1.546, p < 0.001). In the PSM cohort, anemia was still an independent risk factor for all-cause mortality (Model 1: HR = 1.443, 95%CI: 1.256-1.656, p < 0.001; Model 2: HR = 1.357, 95%CI:1.177-1.564, p < 0.001). In the CKD population, anemia patients with FID had the highest risk of mortality than the other anemia groups (p < 0.05), while AID had a mortality rate similar to those without anemia (p > 0.05). In conclusion, anemia was associated with a worse prognosis in patients with CKD, which may be attributed to the higher mortality risk of FID rather than AID. AID wasn't associated with a higher mortality rate compared with CKD patients without anemia.

A systemic review and meta-analysis on the efficacy and safety of ferumoxytol for anemia in chronic kidney disease patients

PURPOSE

To evaluate the efficacy of ferumoxytol, relative to conventional iron supplement formulations, on hemoglobin levels, ferritin level, and adverse event incidence in chronic kidney disease patients.

METHODS

We performed a systematic search of six academic databases (EMBASE, CENTRAL, Scopus, PubMed, Web of sciences, and MEDLINE), adhering to PRISMA guidelines. We performed a meta-analysis on relevant studies to evaluate the overall influence of ferumoxytol, relative to conventional iron supplement formulations, on hemoglobin levels, ferritin level, and treatment related treatment emergent adverse events (TEAEs) incidence in chronic kidney disease patients.

RESULTS

Seven eligible studies were identified from a total of 1397 studies. These studies contained data on 3315 participants with chronic kidney disease (mean age: 59.2 ± 4.6 years). A meta-analysis revealed that ferumoxytol administration had positive effects on hemoglobin levels (Hedge's g statistic: 0.51) and ferritin level (0.88), transferrin saturation (0.39). Besides, we also report reduced incidence of treatment related TEAEs (-0.24) for patients consuming ferumoxytol as compared conventional iron supplement formulations.

CONCLUSIONS

This meta-analysis provides preliminary evidence that ferumoxytol use exerts beneficial effects on the overall hematological outcomes in patients with chronic kidney disease. This study also reports improved treatment related safety profile for ferumoxytol when compared with conventional iron formulations. The findings from this study can have direct implications in forming best practice guidelines for managing anemia in patients with chronic kidney disease.

Glycochenodeoxycholate Affects Iron Homeostasis via Up-Regulating Hepcidin Expression

Increasing hepcidin expression is a vital factor in iron homeostasis imbalance among patients with chronic kidney disease (CKD). Recent studies have elucidated that abnormal serum steroid levels might cause the elevation of hepcidin. Glycochenodeoxycholate (GCDCA), a steroid, is significantly elevated in patients with CKD. However, the correlation between GCDCA and hepcidin has not been elucidated. Decreased serum iron levels and increased hepcidin levels were both detected in patients with CKD in this study. Additionally, the concentrations of GCDCA in nephropathy patients were found to be higher than those in healthy subjects. HepG2 cells were used to investigate the effect of GCDCA on hepcidin in vitro. The results showed that hepcidin expression increased by nearly two-fold against control under 200 μM GCDCA treatment. The phosphorylation of SMAD1/5/8 increased remarkably, while STAT3 and CREBH remained unchanged. GCDCA triggered the expression of farnesoid X receptor (FXR), followed with the transcription and expression of both BMP6 and ALK3 (upward regulators of SMAD1/5/8). Thus, GCDCA is a potential regulator for hepcidin, which possibly acts by triggering FXR and the BMP6/ALK3-SMAD signaling pathway. Furthermore, 40 C57/BL6 mice were treated with 100 mg/kg/d, 200 mg/kg/d, and 300 mg/kg/d GCDCA to investigate its effect on hepcidin in vivo. The serum level of hepcidin increased in mice treated with 200 mg/kg/d and 300 mg/kg/d GCDCA, while hemoglobin and serum iron levels decreased. Similarly, the FXR-mediated SMAD signaling pathway was also responsible for activating hepcidin in liver. Overall, it was concluded that GCDCA could induce the expression of hepcidin and reduce serum iron level, in which FXR activation-related SMAD signaling was the main target for GCDCA. Thus, abnormal GCDCA level indicates a potential risk of iron homeostasis imbalance.

The relationship between FGF23 and anemia in HD and renal transplant patients

PURPOSE

Recent studies claim that FGF23 is also associated with anemia and inflammation. In this study, the relationship between FGF23 and anemia in hemodialysis (HD) and renal transplantation patients (RTx patients) patients was investigated.

METHODS

This was a cross-sectional study involving 40 RTx patients (13 females, 27 males; mean age, 45.93 ± 12.49 years) who had transplantation at least 6 months before, 25 HD patients (12 females, 13 males; mean age, 54.72 ± 15.5 years), and 20 healthy control subjects (13 females, 7 males; mean age, 36.7 ± 9.38 years). FGF23 was studied using Elisa method. Parameters such as iron, ferritin, total iron binding capacity, and transferrin saturation were assessed.

RESULTS

FGF23 level was significantly higher in HD patients when compared with the RTx patients and control groups. In the bivariate correlation analysis, hemoglobin was positively correlated with albumin (r = 0.681, p = 0.000), ferritin (r = 0.446, p = 0.043), and negatively correlated with CRP (r = - 0.476, p = 0.016) and FGF23 (r = 0.493, p = 0.043). FGF23 was found to be an independent predictor of decreased hemoglobin in HD patients. In addition, this association was observed to disappear after transplantation.

CONCLUSION

While FGF23 is closely related to hemoglobin levels in HD patients, we have shown that this relationship disappears after transplantation.

Low hemoglobin levels and an increased risk of psoriasis in patients with chronic kidney disease

Chronic diseases, such as chronic kidney disease (CKD), are frequently accompanied by various comorbidities, including anemia, which is considered a surrogate marker of systemic inflammation. Psoriasis is a chronic inflammatory skin disease prevalent in patients with chronic disease. Psoriasis risk in patients with CKD, however, especially in patients with low hemoglobin levels, has never been investigated. In this study, we investigated associations between low hemoglobin levels and psoriasis in patients with CKD using data from the National Health Insurance Service of Korea. During a mean follow-up period of 6.16 ± 1.02 years, psoriasis was recorded in 13,803 patients with CKD (2.39% of CKD patients). The cumulative incidence of psoriasis was significantly higher in CKD patients with anemia (hemoglobin levels < 13 g/dL in men and < 12 g/dL in women) than those without. In multivariate-adjusted Cox proportional hazards regression models, the risk of psoriasis was significantly higher in anemic CKD patients than nonanemic CKD patients (hazard ratio [HR] 1.136, 95% CI 1.089–1.185, p < 0.001). Additionally, we noted that the incidence of psoriasis decreased with increasing hemoglobin levels in CKD patients (HR 0.953, 95% CI 0.942–0.965, p < 0.001). Altogether, our findings indicate that low hemoglobin levels are significantly related to psoriasis risk in patients with CKD. Further study is required to elucidate whether low hemoglobin levels have an impact on the development of psoriasis or are merely a surrogate marker of psoriasis risk in patients with CKD.

Effectiveness of hypoxia-induced factor prolyl hydroxylase inhibitor for managing anemia in chronic kidney disease: a systematic review and meta-analysis

PURPOSE

To meta-statistically compare the efficiency of hypoxia-induced factor prolyl hydroxylase inhibitor on hemoglobin, ferritin, hepcidin rate, and adverse events.

METHODS

A systematic identification of literature was performed according to PRISMA guidelines on 4 academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis evaluating the influence of hypoxia-induced factors was performed for patients undergoing/not undergoing hemodialysis. The analysis evaluated the efficacy of hypoxia-induced factors on hemoglobin, ferritin, hepcidin rate, and the number of adverse events.

RESULTS

Out of 1052 records, 15 articles including 2045 patients (mean age 62.1 ± 5.4 years) were included in this review. The systematic review presents a 1a level of evidence supporting the use of hypoxia-induced factor for mediating anemia in patients with chronic kidney disease. The meta-analysis reveals medium to large beneficial effects of the hypoxia-induced factor on hemoglobin rate for patients receiving (0.72) and not receiving (1.04) hemodialysis. Moreover, the administration of hypoxia-induced factors was reported to reduce ferritin rate and the hepcidin rate, and the number of adverse events in patients with chronic kidney disease.

CONCLUSION

The current meta-analysis recommends the use of hypoxia-induced factor prolyl hydroxylase inhibitor for managing anemia in chronic kidney disease.

The Association Between Anemia of Chronic Inflammation and Alzheimer's Disease and Related Dementias

Background

Dementia is a spectrum of neurological diseases characterized by memory impairment and cognitive decline with the pathogenesis and effective management remaining elusive. Several studies have identified a correlation between anemia and Alzheimer's disease and related dementias (ADRD); however, anemia subtypes and association with ADRD have yet to be studied conclusively.

Objective

To study an association between ADRD and anemia of chronic inflammation.

Methods

We conducted a retrospective case-control study of the patients, diagnosed with ADRD at Brookdale Hospital. Pair-wise comparisons between means of controls and cases in terms of iron studies and laboratory results were performed using a Mann-Whitney U test. Pair-wise comparisons between anemia subgroups (moderate and severe) were performed using a Two Sample proportion Z-Test, where for each couple of normally distributed population.

Results

There was a total of 4,517 (1,274 ADRD group; 3,243 Control group) patients. There was significant difference in hemoglobin 10.15 versus 11.04 [p-value <0.001]. Iron studies showed a significant difference in ferritin 395±488.18 versus 263±1023.4 [p < 0.001], total iron binding capacity 225±84.08 versus 266±82.30 [p < 0.001] and serum iron level 64±39.34 versus 53±41.83 [p < 0.001]. Folic acid and vitamin B12 levels were normal in both groups. Severe and moderate anemia in the ADRD group were respectively 6.2% [95% CI: 4.2-8.4] and 13% [95% CI: 9.8-16.2] higher. Overall, incidence of moderate-to-severe anemia was found to be 19% higher in ADRD group [95% CI: 15.8-22.1].

Conclusion

We demonstrated an association between ADRD and anemia of chronic inflammation independent of age, renal function, and HgbA1C levels.

How I treat renal anemia

Anemia is a frequent complication of kidney disease. When severe, it causes symptoms that can be debilitating. The course of anemia tends to track the decline in kidney function, with prevalence increasing in more advanced disease. Although the most common cause is relative erythropoietin deficiency, other factors such as reduced iron availability contribute to the pathobiology. In this review, we use cases to explore the surprising complexity of decision-making in management of renal anemia.

The Impact of CKD Anaemia on Patients: Incidence, Risk Factors, and Clinical Outcomes-A Systematic Literature Review

Anaemia is a common consequence of chronic kidney disease (CKD); however, the risk factors for its development and its impact on outcomes have not been well synthesised. Therefore, we undertook a systematic review to fully characterise the risk factors associated with the presence of anaemia in patients with CKD and a contemporary synthesis of the risks of adverse outcomes in patients with CKD and anaemia. We searched MEDLINE, EMBASE, and the Cochrane Library from 2002 until 2018 for studies reporting the incidence or prevalence of anaemia and associated risk factors and/or associations between haemoglobin (Hb) or anaemia and mortality, major adverse cardiac events (MACE), hospitalisation, or CKD progression in adult patients with CKD. Extracted data were summarised as risk factors related to the incidence or prevalence of anaemia or the risk (hazard ratio (HR)) of outcome by Hb level (<10, 10-12, >12 g/dL) in patients not on dialysis and in those receiving dialysis. 191 studies met the predefined inclusion criteria. The risk factor most associated with the prevalence of anaemia was CKD stage, followed by age and sex. Mean HRs (95% CI) for all-cause mortality in patients with CKD on dialysis with Hb <10, 10-12, and >12 g/dL were 1.56 (1.43-1.71), 1.17 (1.09-1.26), and 0.91 (0.87-0.96), respectively. Similar patterns were observed for nondialysis patients and for the risks of hospitalisation, MACE, and CKD progression. This is the first known systematic review to quantify the risk of adverse clinical outcomes based on Hb level in patients with CKD. Anaemia was consistently associated with greater mortality, hospitalisation, MACE, and CKD progression in patients with CKD, and risk increased with anaemia severity. Effective treatments that not only treat the anaemia but also reduce the risk of adverse clinical outcomes are essential to help reduce the burden of anaemia and its management in CKD.

The Influence of Inflammation on Anemia in CKD Patients

Anemia is frequently observed in the course of chronic kidney disease (CKD) and it is associated with diminishing the quality of a patient’s life. It also enhances morbidity and mortality and hastens the CKD progression rate. Patients with CKD frequently suffer from a chronic inflammatory state which is related to a vast range of underlying factors. The results of studies have demonstrated that persistent inflammation may contribute to the variability in Hb levels and hyporesponsiveness to erythropoietin stimulating agents (ESA), which are frequently observed in CKD patients. The understanding of the impact of inflammatory cytokines on erythropoietin production and hepcidin synthesis will enable one to unravel the net of interactions of multiple factors involved in the pathogenesis of the anemia of chronic disease. It seems that anti-cytokine and anti-oxidative treatment strategies may be the future of pharmacological interventions aiming at the treatment of inflammation-associated hyporesponsiveness to ESA. The discovery of new therapeutic approaches towards the treatment of anemia in CKD patients has become highly awaited. The treatment of anemia with erythropoietin (EPO) was associated with great benefits for some patients but not all.

A Placebo-Controlled, Randomized Trial of Enarodustat in Patients with Chronic Kidney Disease Followed by Long-Term Trial

BACKGROUND

Enarodustat (JTZ-951) is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that mimics adaptive responses to hypoxic conditions and may provide a new therapeutic approach for managing anemia in patients with chronic kidney disease (CKD). We evaluated the efficacy, safety, and maintenance dose of enarodustat in anemic patients with CKD not on dialysis.

METHODS

Erythropoiesis-stimulating agent (ESA) naïve patients (correction group) and patients on a stable dose of ESA (conversion group) were randomized to receive 2, 4, or 6 mg of enarodustat or placebo once daily for 6 weeks in a double-blind manner (Period 1) followed by 24 weeks of open enarodustat treatment to maintain their hemoglobin (Hb) levels within a target range of 10.0-12.0 g/dL in reference to a dose adjustment algorithm (Period 2).

RESULTS

In the correction group, Hb level increase rate per week increased in a dose-response manner. The proportion of subjects in the conversion group who maintained Hb levels within ± 1.0 g/dL of baseline did not differ between each enarodustat arm and placebo arm during Period 1. Over 70% of subjects in both groups maintained Hb levels within the target range at the end of treatment in Period 2. The mean prescribed doses were 3.58 and 3.74 mg/day in the correction group and the conversion group, respectively. Enarodustat was associated with decreases in hepcidin and ferritin and increased total iron-binding capacity and was generally well tolerated.

CONCLUSIONS

Enarodustat corrects and maintains Hb levels in anemic patients with CKD not on dialysis.

HIF stabilizers in the management of renal anemia: from bench to bedside to pediatrics

Anemia is a common complication of chronic kidney disease (CKD) in adult and pediatric patients. It has traditionally been treated with erythropoietin therapy and iron supplementation, with great success. With the discovery of the major transcription factor hypoxia inducible factor (HIF) for the erythropoietin gene in 1992, molecules were created that inhibit the HIF prolyl-hydroxylase enzyme. This new class of drug-called HIF stabilizers, or HIF prolyl-hydroxylase inhibitors-prevents the proteasomal degradation of HIF-α, thereby inducing upregulation of the erythropoietin gene. This new strategy for treating CKD anemia is already in phase III clinical trials in adults, and the potential advantages of this therapy are that it is orally active (thereby avoiding injections), and patients are exposed to lower circulating levels of erythropoietin. The long-term safety of this strategy, however, requires elucidation in these trials, particularly since there are many other hypoxia-sensitive genes, notably, angiogenic factors such as vascular endothelial growth factors (VEGF), as well as glycolytic enzymes. As with all new therapies, it is only once a positive benefit: risk profile has been ascertained in adults that the treatment will translate across into pediatrics. Specific issues in the pediatric CKD population are discussed in this review.

Role of hepcidin and iron metabolism in the onset of prostate cancer

The present study aimed to understand the roles of hepcidin and iron metabolism in the onset of prostate cancer. The prostate cancer LNCap, PC3 and DU145 cell lines were transfected with small interfering RNA (siRNA) targeting hepcidin to knockdown hepcidin expression in LNCap, PC3 and DU145 cells. The expression levels of hepcidin in prostate cancer and normal prostate RWPE-1cells were detected by western blot analysis. Exogenous hepcidin was added into the hepcidin-silenced cell lines. Intracellular iron levels were detected using a fluorescence assay, and the proliferative and migratory capacities of cells were detected using the MTT and wound-healing assays, respectively. The apoptotic rate was measured using flow cytometry, and changes in the expression of the iron-export protein ferroportin on the cell membrane were detected by western blot analysis. Hepcidin expression in prostate cancer cells was significantly higher than that of normal prostate cells (P<0.05). Furthermore, the iron levels of hepcidin-silenced cells (hepcidin^-ve groups) were significantly lower than those in the cells treated with exogenous hepcidin (hepcidin^+ve groups) (P<0.05). The proliferative capacity of the hepcidin^+ve cells significantly exceeded those of the hepcidin^-ve groups (P<0.05) and increased over time. In the wound-healing assay, the number of hepcidin^+ve cells present within the scratch sites increased compared with hepcidin^-ve cells, indicating a higher migration rate. Additionally, the expression of ferroportin in the hepcidin^-ve groups significantly exceeded that in the hepcidin^+ve groups (P<0.05). Hepcidin is involved in the onset of prostate cancer, most likely by reducing ferroportin expression and increasing intracellular iron levels to enhance the proliferation, migration and anti-apoptotic capacities of cancer cells.

Changes in Hepcidin and Hemoglobin After Anti-TNF-alpha Therapy in Children and Adolescents With Crohn Disease

OBJECTIVES

Anemia is the most common systemic complication of inflammatory bowel disease, is more common in affected children than in adults, and is mediated in large part by chronic inflammation. Inflammation increases levels of the iron-regulatory protein hepcidin, which have been elevated in adults with Crohn disease.

METHODS

We measured serum hepcidin-25 and hemoglobin (Hgb) in 40 children and adolescents with Crohn disease at baseline and 10 weeks after initiation of anti-tumor necrosis factor (TNF)-α therapy. Measures of disease activity, inflammatory markers, and cytokines were obtained in all subjects. Anemia was defined by World Health Organization criteria.

RESULTS

At baseline hepcidin and C-reactive protein levels were correlated, and 95% of subjects were anemic. After anti-TNF-α therapy, median (interquartile range) hepcidin concentrations decreased significantly and the distribution narrowed (27.9 [16.2, 52.9] vs 23.2 [11.1, 37.7] ng/mL, P = 0.01). Mean (standard deviation) Hgb also increased significantly (10.6 ± 1.2 to 10.9 ± 1.1 g/dL, P = 0.02), and the increase was sustained at 12 months, although 90% of participants continued to meet anemia criteria at 10 weeks. Disease activity and markers of inflammation also decreased and albumin levels increased. In generalized estimating equation analyses, higher TNF-α, interleukin 6, erythrocyte sedimentation rate, and C-reactive protein were associated with higher hepcidin concentrations (P = 0.04, P = 0.03, P = 0.003, and P < 0.001, respectively), and increased levels of disease activity were associated with higher hepcidin.

CONCLUSIONS

In children with Crohn disease, anti-TNF-α therapy is associated with decreased levels of hepcidin and increased Hgb 10 weeks after induction. Improvement in anemia may be a secondary benefit for children who receive this therapy.

Anaemia is an essential complication of ANCA-associated renal vasculitis: a single center cohort study

BACKGROUND

Anaemia is a common complication of patients with antineutrophil cytoplasmic antibody (ANCA)-associated renal vasculitis. Nevertheless, the cause and degree of such cases of anaemia have not been elucidated in detail. We aimed to investigate the prevalence, cause, pathogenesis of anaemia and the impact of anaemia on prognosis in patients with ANCA-associated renal vasculitis.

METHODS

We identified 45 patients with ANCA-associated renal vasculitis that were clinically and/or histologically diagnosed and treated from 2003 to 2014 at University of Tsukuba Hospital. The relationships between anaemia and various clinicopathological findings were evaluated.

RESULTS

At the time of diagnosis of ANCA-associated renal vasculitis, all patients showed anaemia, with a mean haemoglobin level of 7.5 ± 1.3 g/dL. Renal anaemia was diagnosed in 92% of patients, anaemia of chronic disease (ACD) in 56%, and anaemia due to hemorrhage in 20%. Next, the patients were divided into two groups according to anaemia severity: minimum haemoglobin (min Hb) < 7.5 (n = 24) and min Hb ≥ 7.5 (n = 21). A comparison of baseline characteristics showed that serum albumin, maximum serum creatinine, minimum estimated glomerular filtration rate (eGFR), serum cystatin C, and the area of tubulointerstitial damage were significantly different between the haemoglobin groups (p <  0.05). No significant intergroup differences were observed in iron-related or inflammation-related data. With regard to the relationship between anaemia severity and prognosis, patients in the min Hb < 7.5 group tended to have a lower eGFR. Anaemia severity was associated with markedly lower survival (Log-rank test, p = 0.03).

CONCLUSIONS

In this cohort of patients with ANCA-associated renal vasculitis, all subjects exhibited anaemia. In regard to the cause and pathogenesis, the most prevalent form of anaemia was renal anaemia, not ACD, and a potential reason for the high prevalence of anaemia in our cohort may have been the interaction between renal anaemia and ACD. Moreover, anaemia severity was significantly associated with the degree of renal dysfunction and life prognosis.

Current and future chemical therapies for treating anaemia in chronic kidney disease

INTRODUCTION

Erythropoiesis-stimulating agents (ESAs) are not perfect, since they have potential side effects. Iron therapy is also receiving growing attention in recent years. Areas covered: We performed a literature search on PubMed using the following key words: anemia, chronic kidney disease, HIF stabilisers, sotatercept, actin traps, iron, iron-containing phosphate binders, iron dialysate. We reviewed new drugs that are under clinical development to obtain better safety and activity and/or easier and cheaper manufacturing processes in comparison to available ESAs. We also considered new strategies to increase iron stores. Several phase 1 and 2 studies support the beneficial role of increasing Hypoxia Inducible factor (HIF) activity for stimulating endogenous erythropoiesis. Sotatercept and luspatercept, two activin traps, are undergoing clinical development mainly for indications other than CKD. They have the additional effect of improving osteoporosis. Iron-containing phosphate binders have become available recently. Expert opinion: Several medical needs are unmet with ESA. HIF stabilisers are the most appealing drugs undergoing clinical development. They expose patients to lower levels of EPO than ESA, possibly reducing unintended effects. Their long-term safety is still to be demonstrated. One new iron-containing phosphate binders has the potential of combining two indications: hyperphosphoremia and iron deficiency, possibly improving compliance.

Pilot study of the effect of cholecalciferol supplementation on hepcidin in children with chronic kidney disease: Results of the D-fense Trial

BACKGROUND

Hepcidin is a key mediator of the anemia of chronic kidney disease (CKD). There is emerging evidence that 25-hydroxyvitamin D (25D) regulates hepcidin production.

METHODS

A randomized controlled trial of daily vitamin D supplementation for 12 weeks was performed with the aim to test the effects of 4000 versus 400 IU of cholecalciferol on serum hepcidin levels in children with non-dialysis CKD recruited at a tertiary care children's hospital. Hepcidin was quantified using a validated competitive enzyme-linked immunosorbent assay. 25D levels were measured using the chemiluminescence Liaison 25(OH)D assay system. Co-variables included hemoglobin, C-reactive protein, ferritin, and serum calcium and phosphorus for safety monitoring.

RESULTS

A total of 34 subjects were randomized to either the intervention or control group, of whom 26.5% were female and 23.5% were African American. The mean age of the study cohort was 10.9 [standard deviation (SD) 5.8] years, the mean baseline glomerular filtration rate was 60 (SD 17.6) ml/min/1.73 m², and mean baseline 25D level was 29.7 (SD 11.5) ng/ml. At baseline, 50% of subjects were 25D deficient. There were no significant differences in baseline characteristics between the intervention and control groups. Treatment with 4000 IU cholecalciferol was not associated with significant change in hepcidin level at 4 or 12 weeks, and multivariable generalized estimating equation regression demonstrated no significant difference in change in hepcidin over the treatment period in either arm. The median C-reactive protein level decreased significantly at 12 weeks in the intervention group.

CONCLUSIONS

These results do not suggest that daily nutritional vitamin D supplementation modifies serum hepcidin levels in children with CKD. Further study will be required to determine whether supplementation may be effective in children with more advanced CKD or those on dialysis.

The effect of 8-week different-intensity walking exercises on serum hepcidin, IL-6, and iron metabolism in pre-menopausal women

Objective

Hepcidin may be an important mediator in exercise-induced iron deficiency. Despite the studies investigating acute exercise effects on hepcidin and markers of iron metabolism, we found no studies examining the chronic effects of walking exercises (WE) on hepcidin and markers of iron metabolism in premenopausal women. The chronic effects of two 8-week different-intensity WE on hepcidin, interleukin 6 (IL-6), and markers of iron metabolism in pre-menopausal women were examined.

Methods

Exercise groups (EG) [moderate tempo walking group (MTWG), n = 11; brisk walking group (BWG), n = 11] walked 3 days/week, starting from 30 to 51 min. Control group (CG; n = 8) did not perform any exercises. BWG walked at ∼70%–75%; MTWG at ∼50%–55% of HRRmax. VO2max, hepcidin, IL-6, and iron metabolism markers were determined before and after the intervention.

Results

VO2max increased in both EGs, favoring the BWG. Hepcidin increased in the BWG (p < 0.01) and CG (p < 0.05). IL-6 decreased in the BWG and the MTWG (p < 0.05; p < 0.01). While iron, ferritin, transferrin, and transferrin saturation levels did not change in any group, total iron binding capacity (p < 0.05), red blood cells (p < 0.05), and hematocrit (p < 0.01) increased only in the BWG.

Conclusion

Both WE types may be useful to prevent inflammation. However, brisk walking is advisable due to the positive changes in VO2max and some iron metabolism parameters, which may contribute to prevent iron deficiency. The increase in hepcidin levels remains unclear and necessitates further studies.

Ironing out the cross talk between FGF23 and inflammation

The bone-secreted hormone fibroblast growth factor 23 (FGF23) has an essential role in phosphate homeostasis by regulating expression of the kidney proximal tubule sodium-phosphate cotransporters as well as parathyroid hormone levels. Induction of FGF23 early in chronic kidney disease (CKD) helps to maintain normal phosphorous levels. However, high FGF23 levels become pathological as kidney disease progresses and are associated with an increased risk of CKD progression, cardiovascular events, and death. The factors responsible for increasing FGF23 levels early in CKD are unknown, but recent work has proposed a role for inflammation and disordered iron homeostasis. Notably, FGF23 has recently been shown to elicit an inflammatory response and to display immunomodulatory properties. Here, we will review emerging evidence on the cross talk between inflammation, iron, FGF23, and bone and mineral metabolism and discuss the relevance for CKD patients.

Absolute and Functional Iron Deficiency Is a Common Finding in Patients With Heart Failure and After Heart Transplantation

BACKGROUND

Anemia is relatively common in patients with heart failure and heart transplant recipients. Both absolute and functional iron deficiency may contribute to the anemia in these populations. Functional iron deficiency (defined as ferritin greater than 200 ng/mL with TSAT (Transferrin saturation) less than 20%) is characterized by the presence of adequate iron stores as defined by conventional criteria, but with insufficient iron mobilization to adequately support. The aim of this study was to determine prevalence of absolute and functional iron deficiency in patients with heart failure (n = 269) and after heart transplantation (n = 130) and their relation to parameters of iron status and inflammation.

METHODS

Iron status, complete blood count, and creatinine levels were assessed using standard laboratory methods. C-reactive protein, hepcidin and hemojuvelin were measured using commercially available kits.

RESULTS

Absolute iron deficiency was present in 15% of patients with heart failure and 30% in heart transplant recipients, whereas functional iron deficiency was present in 18% of patients with heart failure and 17% in heart transplant recipients. Functional iron deficiency was associated with significantly higher C-reactive protein and hepcidin levels in heart failure patients, and higher hepcidin and lower estimate glomerular filtration rates in heart transplant recipients. Prevalence of anemia (according to the World Health Organization) was significantly higher in heart transplant recipients (40% vs 22%, P < .001), they were also younger, but with worse kidney function than patients with heart failure.

CONCLUSIONS

Both absolute and functional iron deficiency were present in a considerable group of patients. This population should be carefully screened for possible reversible causes of inflammation.

Emerging drugs for the treatment of kidney disease-induced anemia

INTRODUCTION

Anemia has been remained one of the most characteristic and visible manifestations of chronic renal failure. Correction of anemia requires two main treatment strategies: increased stimulation of erythropoiesis, and maintenance of an adequate iron supply to the bone marrow.

AREAS COVERED

Erythropoiesis activating agents became a mainstay in the treatment of renal anemia for more than 25 years. Recently, there have been several attempts to introduce new drugs to stimulate erythropoiesis or affect the hepcidin-ferroportin pathway. Orally available hypoxia-inducible factor (HIF) stabilizing compounds are attractive alternatives. They not only increase hemoglobin, but also suppress hepcidin production and improve iron availability. Novel iron preparations, may also help to ameliorate anemia, with acceptable safety profile and other beneficial properties such a phosphate binding.

EXPERT OPINION

One should be aware of potential risks and benefits of novel sophisticated therapies and their role in the management of renal anemia remain to be established. In particular HIF stabilizers needs to be proven safe, or even safer than ESAs, in large long-term safety studies testing hard end points, due its ubiquitous nature and the regulation of variety of biological processes potentially leading to unexpected side effects. Besides safety, cost-effectiveness appears the major issue in the modern world, including nephrology.

Prospective Assessment of Hepcidin in Relation to Delayed or Immediate Graft Function in Patients Undergoing Kidney Transplantation

BACKGROUND

Hepcidin is a peptide hormone that regulates iron homeostasis. Hepcidin may represent an early, predictive biomarker of acute kidney injury, another model of ischemia-reperfusion injury. Urinary hepcidin-25 has been shown to be elevated in patients who do not develop acute kidney injury. Creatinine is an unreliable indicator during acute changes in kidney; therefore, the aim of the study was to assess whether hepcidin could predict renal outcome in 31 consecutive patients undergoing kidney allograft transplantation. Serum hepcidin was evaluated before and after 1, 3, 6, and 10 days after kidney transplantation, using commercially available kits. Serum creatinine was assessed at the same time.

METHODS

We found a significant decrease in serum hepcidin, as early as after 1 day after kidney transplantation. Before transplantation, serum hepcidin was related to creatinine. In patients with delayed graft function, there was no decrease in serum hepcidin.

RESULTS

Our findings may have important implications for the clinical treatment of patients undergoing kidney transplantation. The "window of opportunity" is narrow in delayed graft function to distinguish between acute rejection and calcineurin inhibitors nephrotoxicity, and time is limited to introduce proper treatment after initiating insult.

CONCLUSIONS

Hepcidin must be investigated as a potential early marker for delayed graft function, especially in the upcoming setting of early dialysis treatment or anti-rejection therapy and might contribute to early patient risk stratification.

Hepatic erythropoietin response in cirrhosis. A contemporary review

The main function of erythropoietin (EPO) is to maintain red blood cell mass, but in recent years, increasing evidence has suggested a wider biological role not solely related to erythropoiesis, e.g. angiogenesis and tissue protection. EPO is produced in the liver during fetal life, but the main production shifts to the kidney after birth. The liver maintains a production capacity of up to 10% of the total EPO synthesis in healthy controls, but can be up-regulated to 90-100%. However, the hepatic EPO synthesis has been shown not to be adequate for correction of anemia in the absence of renal-derived EPO. Elevated circulating EPO has been reported in a number of diseases, but data from cirrhotic patients are sparse and the level of plasma EPO in patients with cirrhosis is controversial. Cirrhosis is characterized by liver fibrosis, hepatic dysfunction and the release of proinflammatory cytokines, which lead to arterial hypotension, hepatic nephropathy and anemia. An increase in EPO due to renal hypoperfusion, hypoxia and anemia or an EPO-mediated hepato-protective and regenerative mechanism is plausible. However, poor hepatic synthesis capacity, a decreasing co-factor level and inflammatory feedback mechanisms may explain a potential insufficient EPO response in end-stage cirrhosis. Finally, the question remains as to whether a potential increase in EPO production in certain stages of cirrhosis originates from the kidney or liver. This paper aims to review contemporary aspects of EPO relating to chronic liver disease.

Hepcidin as a Biomarker of Impaired Renal Function in Rat Models for Chronic Allograft Nephropathy

BACKGROUND To explore the use of hepcidin as a marker of impaired renal function in a rat model for chronic allograft nephropathy (CAN). MATERIAL AND METHODS Twenty-four models were developed and 20 models were included in this study, using Fisher (F344) rats (donors) and Lewis rats (recipients). Renal function tests were performed preoperatively and postoperatively. Hepcidin, interleukin-6 (IL-6), and erythropoietin levels in serum and urine were measured by enzyme-linked immunosorbent assay (ELISA). To observe pathological changes in the kidneys, 10 rats each were sacrificed at 2 months and 4 months after surgery. RESULTS After transplantation, the serum hepcidin and IL-6 levels increased, while urine hepcidin levels decreased. Erythropoietin levels showed a similar trend; all P<0.05. Serum creatinine (SCr) and blood urea nitrogen significantly increased post-operatively, with SCr positively correlating with serum hepcidin. Serum hepcidin positively correlated with IL-6 and negatively correlated with EPO. Histopathological results were consistent with CAN, after transplantation. CONCLUSIONS Hepcidin may be considered as a potential marker of impaired renal function.

C-reactive protein but not hepcidin, NGAL and transferrin determines the ESA resistance in hemodialysis patients

BACKGROUND

Erythropoiesis-stimulating agents (ESA) are commonly used for the treatment of anemia in hemodialysis (HD) patients, however, 5-10% of these patients have resistance to ESA treatment. Hepcidin and neutrophil-gelatinase associated lipocalin (NGAL) are induced by inflammation and these proteins may take role in ESA resistance. Herein, we aimed to investigate the effects of serum hepcidin, NGAL, transferrin and C-reactive protein (CRP) levels on ESA resistance in HD patients.

METHODS

A total of 63 chronic HD patients (6.0 ± 17 years, M/F:44/19) and 20 healthy controls (6.0 ± 4 years, M/F:14/6) were enrolled. ESA resistance index (ERI) was calculated as weekly ESA dose (IU)/body weight (kg)/hemoglobin level (g/dL). Patients on ESA treatment were divided into two groups depending on the median ERI value as low and high ERI groups.

RESULTS

Serum ferritin, hepcidin and NGAL levels were significantly higher in HD patients compared with controls. Serum transferrin levels were lower in high ESA index group compared with patients without ESA treatment and healthy controls. ERI was significantly correlated with serum CRP levels (r = 0.55, p < 0.001). In HD patients, serum hepcidin levels were associated with ferritin (r = 0.55, p < 0.01) and creatinine (r = 0.27, p = 0.03). Dose of ESA was significantly associated with serum CRP (r = 0.34, p = 0.02), total protein (r = -0.34, p = 0.01), transferrin (r = -0.28, p = 0.04) and ferritin (r = 0.31, p = 0.02). In linear regression analysis to predict ERI, age, gender, serum CRP, hepcidin, NGAL, albumin, ferritin and BMI were included (Model R = 0.62, R(2) =0 .38, p = 0.02). Serum CRP was the only significant factor predicting ERI.

CONCLUSION

CRP was the only predictor of ESA resistance index in HD patients. Hepcidin, NGAL and transferrin were not found to be markers of ESA resistance.

Minor Elevation in C-Reactive Protein Levels Predicts Incidence of Erythropoiesis-Stimulating Agent Hyporesponsiveness among Hemodialysis Patients

BACKGROUND

Hemodialysis (HD) patients occasionally experience minor asymptomatic elevation in C-reactive protein (CRP) levels, which may be associated with difficulty in managing renal anemia using erythropoiesis-stimulating agents (ESAs). Here, we assessed whether elevation of CRP predicts future incidences of ESA hyporesponsiveness.

METHODS

A total of 2,956 HD patients lacking ESA hyporesponsiveness and infectious diseases were enrolled, and the association between CRP levels and incidence of ESA hyporesponsiveness was assessed. CRP levels were divided into 4 categories (normal [<1.0 mg/l], mild [1.0 ≤ CRP <3.0 mg/l], moderate [3.0 ≤ CRP <10.0 mg/l] and high [≥ 10.0 mg/l]). The primary outcome was the cumulative incidence of ESA hyporesponsiveness, defined as a failure to achieve hemoglobin level ≥ 10 g/dl despite receiving high doses of ESAs (≥ 9,000 U/week recombinant human epoetin [rHuEPO]-α or rHuEPO-β and ≥ 60 μg/week darbepoetin-α) during 12 months of follow-up.

RESULTS

The cumulative incidence of ESA hyporesponsiveness was 134 (4.8%) occurrences over 4 months and 300 (12.4%) over 12 months. The elevated CRP groups had significantly higher incidence of ESA hyporesponsiveness over 4 months of follow-up than the normal reference group (adjusted relative risk [RR] 1.6, 95% CI 1.0-2.6 for moderate; adjusted RR 2.5, 95% CI 1.5-4.1 for high). Furthermore, the association remained consistent even over 12 months (adjusted RR 1.4, 95% CI 1.0-1.8 for moderate; adjusted RR 1.6, 95% CI 1.1-2.4 for high).

CONCLUSIONS

Elevated CRP levels were associated with future incidence of ESA hyporesponsiveness from low-grade inflammation (3.0 ≤ CRP <10.0 mg/l).

Cardiorenal Syndrome and the Role of the Bone-Mineral Axis and Anemia

The association between chronic kidney disease (CKD) and cardiovascular disease (CVD) is well established, and there is mounting evidence of interorgan cross talk that may accelerate pathologic processes and the progression of organ dysfunction in both systems. This process, termed cardiorenal syndrome (CRS) by the Acute Dialysis Quality Initiative, is considered a major health problem: patients with CKD and CVD are at much higher risk of mortality than patients with either condition alone. To date, the majority of CRS research has focused on neurohormonal mechanisms and hemodynamic alterations. However, mounting evidence suggests that abnormalities in the normal pathophysiology of the bone-mineral axis, iron, and erythropoietin play a role in accelerating CKD and CVD. The goal of this article is to review the role and interrelated effects of the bone-mineral axis and anemia in the pathogenesis of chronic CRS.

Iron-hepcidin dysmetabolism, anemia and renal hypoxia, inflammation and fibrosis in the remnant kidney rat model

Anemia is a common complication of chronic kidney disease (CKD) that develops early and its severity increases as renal function declines. It is mainly due to a reduced production of erythropoietin (EPO) by the kidneys; however, there are evidences that iron metabolism disturbances increase as CKD progresses. Our aim was to study the mechanisms underlying the development of anemia of CKD, as well as renal damage, in the remnant kidney rat model of CKD induced by 5/6 nephrectomy. This model of CKD presented a sustained degree of renal dysfunction, with mild and advanced glomerular and tubulointerstitial lesions. Anemia developed 3 weeks after nephrectomy and persisted throughout the protocol. The remnant kidney was still able to produce EPO and the liver showed an increased EPO gene expression. In spite of the increased EPO blood levels, anemia persisted and was linked to low serum iron and transferrin levels, while serum interleukin (IL)-6 and high sensitivity C-reactive protein (hs-CRP) levels showed the absence of systemic inflammation. The increased expression of duodenal ferroportin favours iron absorption; however, serum iron is reduced which might be due to iron leakage through advanced kidney lesions, as showed by tubular iron accumulation. Our data suggest that the persistence of anemia may result from disturbances in iron metabolism and by an altered activity/function of EPO as a result of kidney cell damage and a local inflammatory milieu, as showed by the increased gene expression of different inflammatory proteins in the remnant kidney. In addition, this anemia and the associated kidney hypoxia favour the development of fibrosis, angiogenesis and inflammation that may underlie a resistance to EPO stimuli and reduced iron availability. These findings might contribute to open new windows to identify putative therapeutic targets for this condition, as well as for recombinant human EPO (rHuEPO) resistance, which occurs in a considerable percentage of CKD patients.

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.

Reduced red blood cell count predicts poor survival after surgery in patients with primary liver cancer

Currently, the optimal therapy of primary liver cancer (PLC) remains to be hepatic resection. For better management of the patients, we evaluated the prognostic predicting value of red blood cell (RBC) count, a routine laboratory parameter, on the long-term survival of patients who underwent surgical treatment. Clinical and laboratory data of 758 patients, who underwent surgical hepatic resection, were retrospectively studied by χ2 tests and logistic regression. All patients were enrolled at Henan Cancer Hospital, Zhengzhou, China, from February 2009 to July 2013, and none of them received any other treatments before surgery. Kaplan-Meier survival analysis and Cox proportional hazard models were used to examine the influence of RBC counts on patients' survival. The Cox univariate and multivariate analyses showed that preoperative RBC count was an independent risk factor of poor prognosis after surgical treatment. The Kaplan-Meier curves showed that the overall survival (OS) of patients without reduced preoperative RBC counts was significantly better than those patients with reduced preoperative RBC counts (P < 0.001). Concordantly, compared with the patients with either reduced preoperative and/or postoperative RBC counts, patients without reduced RBC counts preferred to be low Child-Pugh grades (P = 0.0065), which implies a better hepatic function. In addition, low RBC count was found to be significantly associated with patients of female (P = 0.003), younger age (P =  < 0.001), and with higher AST/ALT ratio (P = 0.005). This study revealed that patients with preoperative RBC counts lower than normal had worse OS rates than those without reduced preoperative RBC counts, perhaps due to the significant correlation of reduced preoperative RBC count to patients' worse Child-Pugh grade that reflect the loss of liver functions.

Haemolysis and perturbations in the systemic iron metabolism of suckling, copper-deficient mosaic mutant mice - an animal model of Menkes disease

The biological interaction between copper and iron is best exemplified by the decreased activity of multicopper ferroxidases under conditions of copper deficiency that limits the availability of iron for erythropoiesis. However, little is known about how copper deficiency affects iron homeostasis through alteration of the activity of other copper-containing proteins, not directly connected with iron metabolism, such as superoxide dismutase 1 (SOD1). This antioxidant enzyme scavenges the superoxide anion, a reactive oxygen species contributing to the toxicity of iron via the Fenton reaction. Here, we analyzed changes in the systemic iron metabolism using an animal model of Menkes disease: copper-deficient mosaic mutant mice with dysfunction of the ATP7A copper transporter. We found that the erythrocytes of these mutants are copper-deficient, display decreased SOD1 activity/expression and have cell membrane abnormalities. In consequence, the mosaic mice show evidence of haemolysis accompanied by haptoglobin-dependent elimination of haemoglobin (Hb) from the circulation, as well as the induction of haem oxygenase 1 (HO1) in the liver and kidney. Moreover, the hepcidin-ferroportin regulatory axis is strongly affected in mosaic mice. These findings indicate that haemolysis is an additional pathogenic factor in a mouse model of Menkes diseases and provides evidence of a new indirect connection between copper deficiency and iron metabolism.

Hepcidin-25 concentrations are markedly increased in patients with chronic kidney disease and are inversely correlated with estimated glomerular filtration rates

BACKGROUND

Hepcidin-25 regulates iron homeostasis by binding the iron transporter ferroportin, causing its degradation. Increased hepcidin-25 causes decreased intestinal iron absorption and release from intracellular stores. Our objective in this study was to measure hepcidin-25 levels in patients with chronic kidney disease (CKD) to determine if they might contribute to the anemia of CKD.

METHODS

We used a hepcidin-25-specific enzyme-linked immunosorbent assay to measure hepcidin-25 in 103 CKD patients and 100 healthy individuals. We assessed in CKD subjects the correlation of hepcidin-25 with creatinine, estimated glomerular filtration rate (eGFR), hemoglobin, blood urea nitrogen, serum iron, transferrin, and ferritin.

RESULTS

Hepcidin-25 concentrations in CKD patients were significantly increased compared to healthy subjects (60.4 ± 6.1 μg/l vs. 3.0 ± 0.5 μg/l, P < 0.001). Hepcidin-25 concentrations were directly correlated with creatinine (R = 0.28, P = 0.004) and inversely correlated with eGFR (R = -0.32, P = 0.001). Hepcidin-25 levels were also correlated with transferrin (R = -0.28, P = 0.004) and ferritin (R = 0.80, P < 0.001).

CONCLUSION

The direct correlation of hepcidin-25 with creatinine and its inverse correlation with eGFR suggest that hepcidin-25 levels increase as renal function deteriorates, possibly due to decreased hepcidin-25 renal clearance.

Potential effects of omega-3 fatty acids on anemia and inflammatory markers in maintenance hemodialysis patients

BACKGROUND

Anemia is a common complication among hemodialysis (HD) patients. Although intravenous iron and erythropoiesis-stimulating agents revolutionized anemia treatment, about 10% of HD patients show suboptimal response to these agents. Systemic inflammation and increased serum hepcidin level may contribute to this hyporesponsiveness. Considering the anti-inflammatory properties of omega-3 fatty acids, this study aimed to evaluate potential role of these fatty acids in improving anemia and inflammation of chronic HD patients.

METHODS

In this randomized, placebo-controlled trial, 54 adult patients with HD duration of at least 3 months were randomized to ingest 1800 mg of either omega-3 fatty acids or matching placebo per day for 4 months. Anemia parameters including blood hemoglobin, serum iron, transferrin saturation (TSAT), erythropoietin resistance index, and required dose of intravenous iron and erythropoietin, and serum concentrations of inflammatory/anti-inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, C-reactive protein (CRP), hepcidin, ferritin, intact parathyroid hormone (iPTH), and ratios of IL-10 to IL-6 and IL-10 to TNF-α were measured at baseline and after 4 months of the intervention.

RESULTS

45 subjects (25 in the omega-3 and 20 in the placebo group) completed the study. No significant changes were observed in blood hemoglobin, serum iron, TSAT, and required dose of intravenous iron in either within or between group comparisons. Additionally, erythropoietin resistance index as well as required dose of intravenous erythropoietin showed no significant change in the omega-3 group compared to the placebo group. Although a relative alleviation in inflammatory state appeared in the omega-3 group, the mean differences of inflammatory and anti-inflammatory markers between the two groups did not reach statistically significant level except for IL-10-to-IL-6 ratio and serum ferritin level which showed significant changes in favor of omega-3 treatment (P <0.001 and P = 0.003, respectively).

CONCLUSION

Omega-3 fatty acids relatively improved systemic inflammation of chronic HD patients without any prominent benefits on anemia. However, future well-designed studies on larger number of patients may determine utility of omega-3 fatty acids in HD patients with respect to inflammation and anemia.

New renal anemia drugs: is there really anything new on the horizon?

Anemia has remained one of the most characteristic and visible manifestations of chronic renal failure for over 150 years. The pathogenesis of anemia of chronic kidney disease (CKD) is multifactorial with inadequate production of erythropoietin being the leading factor. The development of recombinant human erythropoietin (epoetin) in the late 1980s was a milestone in treatment of renal anemia. Despite new drugs, our 'good old friend' erythropoietin-stimulating agents are our everyday life in nephrology practice. It seems that peginesatide would not become a new approach for treating anemia of CKD patients, but rather a falling star. Several new strategies for treating the anemia of CKD are currently being investigated in clinical trials, including prolyl hydroxylase inhibitors and modulators of hepcidin activity, but their role in the management of this condition remains to be established. As shown by the expert in this review, we have to take into account not only the safety and convenience of administration but also cost-effectiveness, while biosimilars are consequently knocking at the doors of dialysis units more and more, particularly in Europe.

The removal of serum hepcidin by different dialysis membranes

PURPOSE

Hepcidin has been suspected to be associated with anemia of chronic disease, which is commonly observed in patients with maintenance hemodialysis (MHD). As almost of hepcidin is bounded to protein, it is essential to clarify which kind of dialysis membrane can remove it efficiently.

METHODS

Ex vivo study: 50 mL of whole blood from healthy volunteers were circulated for 2 h in a microcircuit with mini-dialyzers (acrylonitrile-co-methallyl sulfonate (AN69) or polysulfone (PS)) without ultrafiltration. We measured hepcidin-25 levels at 0, 60, and 120 min in the blood samples. In vivo study: Blood samples were taken from 28 MHD patients at the start and end of HD sessions with PS or AN69. We measured serum levels of hepcidin 20, 22, and 25 by liquid chromatography tandem mass spectrometry, and also measured serum levels of urea nitrogen (UN), β2microglobulin (MG).

RESULTS

Ex vivo study: Although serum hepcidin 25 levels increased after the ex vivo session with PS, they significantly decreased with AN69. In vivo study: The reduction ratio of β2MG by PS was significantly higher than that of AN69. On the other hand, there was no significant difference in the reduction ratio of hepcidin 20, 22, and 25 between PS and AN69.

CONCLUSIONS

Both super-flux PS and AN69 similarly removed hepcidin 20 22, and 25. HD with PS might achieve a high removal ratio of hepcidin by enhanced diffusion performance and an increased clearance of small molecule solutes. On the other hand, AN69 might remove hepcidin by adsorption.

Hepcidin, iron status, and inflammation variables among healthy pregnant women in the Turkish population

PURPOSE

To investigate hepcidin levels in each trimester and their association with other haematological variables and inflammation markers during normal pregnancy among low-risk pregnant women in rural Turkey.

METHOD

The series comprised 103 healthy Turkish primigravida women with a normal pregnancy. Blood samples were obtained at 11-14, 24-28 and 30-34 weeks of gestation. Haemoglobin, hematocrit, red cell indices, white blood cell count, platelet count, iron status indicators (plasma iron, transferrin, ferritin levels and iron binding capacity), serum hepcidin, interleukin-6 and C-reactive protein levels were analysed. The proportions were compared using Pearson's χ2 test or Friedman's test.

RESULTS

The mean serum hepcidin concentrations at 11-14, 24-28 and 30-34 weeks of gestation were as follows: 7.8 ± 3.4 ng/mL, 8.6 ± 3.1 ng/mL and 7.3 ± 3.0 ng/mL, respectively. The mean serum ferritin concentrations with median values at each trimester were 14.2 (11.5), 9.5 (8.8) and 11.2 (9.3), respectively. The mean serum CRP values at each trimester were 5.1 (4.0), 5.5 (4.6) and 6.0 (5.5), respectively. The serum hepcidin levels were not related to iron status or the haemoglobin, IL-6 or C-reactive protein levels.

CONCLUSIONS

There was no association between serum hepcidin and serum ferritin, IL-6 or CRP concentrations in each trimester among low-risk pregnant women.

The A736V TMPRSS6 polymorphism influences hepcidin and iron metabolism in chronic hemodialysis patients: TMPRSS6 and hepcidin in hemodialysis

BACKGROUND

Aim of this study was to evaluate whether the A736V TMPRSS6 polymorphism, a major genetic determinant of iron metabolism in healthy subjects, influences serum levels of hepcidin, the hormone regulating iron metabolism, and erythropoiesis in chronic hemodialysis (CHD).

METHODS

To this end, we considered 199 CHD patients from Northern Italy (157 with hepcidin evaluation), and 188 healthy controls without iron deficiency, matched for age and gender. Genetic polymorphisms were evaluated by allele specific polymerase chain reaction assays, and hepcidin quantified by mass spectrometry.

RESULTS

Serum hepcidin levels were not different between the whole CHD population and controls (median 7.1, interquartile range (IQR) 0.55-17.1 vs. 7.4, 4.5-17.9 nM, respectively), but were higher in the CHD subgroup after exclusion of subjects with relative iron deficiency (p = 0.04). In CHD patients, the A736V TMPRSS6 polymorphism influenced serum hepcidin levels in individuals positive for mutations in the HFE gene of hereditary hemochromatosis (p < 0.0001). In particular, the TMPRSS6 736 V variant was associated with higher hepcidin levels (p = 0.017). At multivariate analysis, HFE and A736V TMPRSS6 genotypes predicted serum hepcidin independently of ferritin and C reactive protein (p = 0.048). In patients without acute inflammation and overt iron deficiency (C reactive protein <1 mg/dl and ferritin >30 ng/ml; n = 86), hepcidin was associated with lower mean corpuscular volume (p = 0.002), suggesting that it contributed to iron-restricted erythropoiesis. In line with previous results, in patients without acute inflammation and severe iron deficiency the "high hepcidin" 736 V TMPRSS6 variant was associated with higher erythropoietin maintenance dose (p = 0.016), independently of subclinical inflammation (p = 0.02).

CONCLUSIONS

The A736V TMPRSS6 genotype influences hepcidin levels, erythropoiesis, and anemia management in CHD patients. Evaluation of the effect of TMPRSS6 genotype on clinical outcomes in prospective studies in CHD may be useful to predict the outcomes of hepcidin manipulation, and to guide treatment personalization by optimizing anemia management.

Circulating human hepcidin-25 concentrations display a diurnal rhythm, increase with prolonged fasting, and are reduced by growth hormone administration

BACKGROUND

Hepcidin-25 reduces iron absorption by binding to the intestinal iron transporter ferroportin and causing its degradation. Currently, little is known about the basal regulation of circulating hepcidin-25. In addition, although erythropoietin administration has been reported to decrease the circulating hepcidin concentration, information is limited regarding how other stimulators of erythropoiesis, such as growth hormone (GH), might alter hepcidin-25 concentrations.

METHODS

We used a sensitive and specific hepcidin-25 dual-monoclonal antibody sandwich immunoassay to measure hepcidin-25 in healthy human volunteers at various time points throughout the day and during 3 days of fasting and subsequent refeeding. We also measured hepcidin-25 concentrations in healthy volunteers after GH administration.

RESULTS

In healthy individuals, hepcidin-25 concentrations displayed a diurnal variation, with concentrations being lowest in the early morning and steadily increasing throughout the day before declining during the evening hours, a pattern that was not influenced by food intake. Prolonged fasting produced statistically significant increases in hepcidin-25 concentrations. Refeeding reversed this process, and GH administration markedly decreased hepcidin-25 concentrations.

CONCLUSIONS

Our results indicate that in humans, hepcidin-25 exhibits diurnal changes that can be altered by prolonged fasting, which increases hepcidin-25 concentrations approximately 3-fold after 3 days of fasting, possibly owing to a suppression of erythropoiesis that may occur during the fasting state to preserve tissue iron concentrations. In contrast, GH administration decreased hepcidin-25 concentrations by approximately 65%, presumably by stimulating erythropoiesis. These results indicate that circulating hepcidin-25 concentrations display much more dynamic and rapid variation than might have been anticipated previously.

Vitamin C affects the expression of hepcidin and erythropoietin receptor in HepG2 cells

BACKGROUNDS

Hepcidin modulates the de novo absorption of iron from the duodenum and the recycling of iron released from the reticuloendothelial system. In patients with chronic renal failure, administration of higher doses of erythropoietin (EPO) or vitamin C (Vit C) can correct the functional iron deficiency. While EPO-regulated hepcidin expression within hepatocytes has been recently identified, the relation between vitamin C with hepcidin expression is still uncertain.

METHODS

Hepcidin-producing HepG2 cells (a human liver carcinoma cell line) were cultured with 50- to 100-μg/mL vitamin C or 0.25- to 1.0-U/mL EPO for 6 hours. Reverse transcription polymerase chain reaction was performed for quantitative measurements of hepcidin, EPO, and EPO receptor (EPOR) expression.

RESULTS

EPO and vitamin C inhibited hepcidin expression within HepG2 cells; the EPO effect was dose dependent. EPO downregulated EPOR and vitamin C and upregulated EPOR. However, vitamin C had little effect on the expression of EPO.

CONCLUSIONS

EPO is capable of downregulating EPOR when it acts early. Vitamin C directly inhibits hepcidin expression within HepG2 cells. Moreover, by enhancing EPOR production, vitamin C may correct the downregulating EPOR from EPO, which has additional effect with EPO in treating anemia.

Hepcidin in anemia of chronic kidney disease: review for the pediatric nephrologist

Anemia coincident with hyporesponsiveness to erythropoiesis-stimulating agents is an ongoing and prevalent problem in children with chronic kidney disease (CKD). The recently identified iron-regulatory protein hepcidin appears likely to play a significant role in this problem. Hepcidin up-regulation in the setting of CKD, with subsequent increased serum levels, results in impaired iron absorption from the intestine and decreased iron release from body storage sites. Ultimately, in the setting of such elevated levels, a state of functional iron deficiency may develop and lead to anemia due to iron-restricted erythropoiesis. Elevated hepcidin levels are expected in the face of decreased glomerular filtration rate and inflammation. Based on current evidence, it seems likely that hepcidin represents a potentially modifiable mediator of anemia of CKD and is thus a potential target for future anemia therapy. Currently, increased removal via intensified dialysis and-/or blockade of the inflammatory pathway appear to be two viable generic strategies for reducing hepcidin levels. Goals of directly manipulating the hepcidin pathway should offer the pediatric clinician new options for treating the complex anemia associated with CKD.

Anemia in children with chronic kidney disease

Anemia is a common comorbidity in children with chronic kidney disease (CKD). This condition is associated with multiple adverse clinical consequences and its management is a core component of nephrology care. Increased morbidity and mortality, increased risk of cardiovascular disease and decreased quality of life have been associated with anemia of CKD in children. Although numerous complex factors interact in the development of this anemia, erythropoietin deficiency and iron dysregulation (including iron deficiency and iron-restricted erythropoiesis) are the primary causes. In addition to iron supplementation, erythropoietin-stimulating agents (ESAs) can effectively treat this anemia, but there are important differences in ESA dose requirements between children and adults. Also, hyporesponsiveness to ESA therapy is a common problem in children with CKD. Although escalating ESA doses to target increased hemoglobin values in adults has been associated with adverse outcomes, no studies have demonstrated this association in children. The question of appropriate target hemoglobin levels in children, and the approach by which to achieve these levels, remains under debate. Randomized, controlled studies are needed to evaluate whether normalization of hemoglobin concentrations is beneficial to children, and whether this practice is associated with increased risks.

Serum hepcidin as a diagnostic test of iron deficiency in premenopausal female blood donors

BACKGROUND

Currently used indicators of iron status have limitations. Hepcidin, a key regulator of iron metabolism, is reduced in iron deficiency. We sought to determine the properties of hepcidin as a diagnostic test of iron deficiency.

DESIGN AND METHODS

Sera from female, non-anemic, whole blood donors were analyzed for hepcidin (enzyme-linked immunosorbent assay), ferritin, soluble transferrin receptor and C-reactive protein. Iron deficiency was defined as (i) serum ferritin less than 15 ng/mL or (ii) soluble transferrin receptor /log(ferritin) index greater than 3.2 if the C-reactive protein concentration was less than 10 mg/L, or greater than 2.2 if the C-reactive protein concentration was greater than 10 mg/L). Receiver operating characteristic curves were plotted to determine the overall utility and identify optimal cut-points of hepcidin as a test of iron deficiency.

RESULTS

In 261 blood donors the prevalence of iron deficiency defined by ferritin concentration was 59/261 [22.6% (17.5, 27.7)], whereas defined by soluble transferrin receptor/log(ferritin) index it was 53/261 [20.4% (15.4, 25.2)]. The 95% reference range of hepcidin concentration in the iron-replete population was 8.2-199.7 ng/mL. The area under the receiver operating characteristic curve for hepcidin compared with ferritin concentration less than 15 ng/mL was 0.87 (0.82, 0.92), while that compared with the soluble transferrin receptor /log(ferritin) index was 0.89 (95% CI 0.84, 0.93). For a diagnosis of iron deficiency defined by the soluble transferrin receptor/log(ferritin) index, hepcidin less than 8 ng/mL had a sensitivity of 41.5% and a specificity of 97.6%, while hepcidin less than 18 ng/mL had a sensitivity of 79.2% and a specificity of 85.6%.

CONCLUSIONS

Serum hepcidin concentration may be a useful indicator of deficient iron stores. Further studies are required to evaluate the role of hepcidin in the diagnosis of iron deficiency in other groups of patients.

Design and Rationale for the Study of Changes in Iron and Atherosclerosis Risk in Perimenopause

This study seeks to investigate changes in iron homeostasis and carotid arteries in women at risk of atherosclerosis, addressing a relatively unexplored hypothesis explaining why women have a 5-10 year lag in initial atherosclerotic events. Recent evidence points to hepcidin, the key regulator of macrophage iron uptake and release, as a potential mediator of risk. Furthermore, iron catalyzes the generation of free radicals that oxidize cholesterol stimulating atheroma formation. Magnetic resonance imaging (MRI) is ideally suited to study iron because of iron's local effects on magnetic susceptibility that can be quantified using a relaxation parameter called T2* ('T2-star'), as well as the ability to noninvasively characterize and quantify atherosclerotic plaque with MRI. This work outlines the rationale and study design to provide critical evidence related to the iron hypothesis, such that novel diagnostics and therapeutics to attenuate risk may be derived from a better understanding of iron's role in atherosclerosis.

A dual-monoclonal sandwich ELISA specific for hepcidin-25

BACKGROUND

Hepcidin, a key regulator of iron metabolism, binds to the iron transporter ferroportin to cause its degradation. In humans, hepcidin deficiency has been linked to hemochromatosis and iron overload, whereas increased concentrations have been reported in anemia of cancer and chronic disease. There is currently an unmet clinical need for a specific immunoassay with a low limit of quantification to measure serum concentrations of hepcidin-25, the active form of the protein.

METHODS

We generated 2 antihepcidin-25 monoclonal antibodies and used them to build a sandwich ELISA. We correlated ELISA results to hepcidin-25 measurements by LC-MS and used ELISA to measure serum hepcidin-25 concentrations in normal individuals, cancer patients, and patients with rheumatoid arthritis.

RESULTS

The sandwich ELISA was highly specific for hepcidin-25, having a limit of quantification of 0.01 μg/L (10 pg/mL). Serum concentrations of hepcidin-25 measured by ELISA correlated with hepcidin-25 concentrations measured by using an independent LC-MS assay (r = 0.98, P < 0.001). Hepcidin-25 concentrations were increased in patients with cancer (median 54.8 μg/L, 25%-75% range 23.2-93.5 μg/L, n = 34) and rheumatoid arthritis (median 10.6 μg/L, 25%-75% range 5.9-18.4 μg/L, n = 76) compared with healthy individuals (median 1.20 μg/L, 25%-75% range 0.42-3.07 μg/L, n = 100).

CONCLUSIONS

The use of 2 monoclonal antibodies in a sandwich ELISA format provides a robust and convenient method for measuring concentrations of the active form of hepcidin. This ELISA should help to improve our understanding of the role of hepcidin in regulating iron metabolism.