Iron and Chronic Kidney Disease: Still a Challenge

Effectiveness of Lactoferrin in the Treatment of Anemia in Chronic Kidney Disease: A Single-Center Pilot Study

Background

Anemia occurs in majority of patients with chronic kidney disease despite adequate dialysis and iron replete status. This study was done to evaluate the effects of lactoferrin with or without iron supplementation for the treatment of anemia in patients with chronic kidney disease (CKD).

Materials and Methods

In this prospective, observational, single-center, single-arm pilot study, adult patients aged >18 years, having stage 5 CKD (estimated glomerular filtration rate [eGFR] <15 ml/min/1.73 m2), and who had anemia (hemoglobin [Hb] <10 g/dl; transferrin saturation [Tsat] >20%) were included. Patients were treated with 100 mg of oral lactoferrin twice a day for one month with or without iron supplementation. Patients had been on stable erythropoietin doses for ≥1 month prior to inclusion in the study. We report on the improvement in Hb levels and effect on inflammatory markers from baseline at four weeks.

Results

A total of 46 CKD patients having anemia were included. Patients had a mean age of 39.3 years, and a majority were men (69.6%). Improvement in the mean (SD) Hb level (g/dl) was observed from baseline (8.18 [1.19]) to Week 2 (8.54 [1.57]), which attained significance at Week 4 (8.96 [1.93]; P < 0.001; mean difference: -0.76; 95% confidence interval [CI]: -1.291 to - 0.2383). The improvement in Hb was higher in women than in men (P = 0.48) and in patients receiving lactoferrin with iron supplementation than in those receiving lactoferrin alone (P = 0.14). There was a non-significant decrease in the erythrocyte sedimentation rate (P = 0.14) and a non-significant increase in C-reactive protein (P = 0.54) level.

Conclusion

Oral lactoferrin therapy was effective in improving hemoglobin levels in patients with advanced CKD and anemia. The effects of lactoferrin therapy on inflammatory markers remain uncertain.

Iron Management and Anemia in Patients on the Active Kidney Transplant List

INTRODUCTION

Iron metabolism disorders and anemia are one of the main complications of end-stage renal disease that may affect the evaluation process for kidney transplantation. The study aimed to assess the iron metabolism in hemodialysis patients in relation to waiting list status.

STUDY METHOD

The study included 5068 hemodialysis patients, including those on the active waiting list (N = 449) and those who were not eligible for the waitlist (N = 4619). Demographic and biochemical data, Charlson's comorbidity index, duration of hemodialysis therapy and, respectively, hemoglobin, ferritin, and transferrin saturation levels were compared in both groups of patients.

RESULTS

Patients on the active waiting list were significantly younger -53.2 vs 67.2 years (P < .001), with a lower Charlson comorbidity index score: 3.33 vs 4.42 (P < .001). The duration of hemodialysis therapy was similar: 66.0 vs 63.2 months (P = .416), the incidence of anemia according to World Health Organization (90.6%, vs 91.2%) and KDIGO (72.4% vs 70.4%). The degree of anemia correction in terms of hemoglobin concentration and transferrin saturation was comparable in both groups and amounted to an average of 10.9 g/dL (P = .349) for hemoglobin concentration and 32.7% vs 33.4% (P = .513) for transferrin saturation. However, there was a statistically significant difference in ferritin concentration: 554 ug/L vs 733 ug/L (P = .001).

CONCLUSIONS

Patients on the active list have significantly lower ferritin levels despite similar duration of hemodialysis treatment and comparable hemoglobin values. This may be due to lower inflammation, and less frequent blood transfusions, and lead to a lower risk of immunization and an increased chance of potential kidney transplantation.

Impact of HIF prolyl hydroxylase inhibitors in heart failure patients with renal anemia

OBJECTIVE

Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors are a new class of anti-anemia agents. We retrospectively evaluated the safety and efficacy of HIF-PH inhibitors in patients with heart failure (HF) complicated by anemia associated with chronic kidney disase. HIF-PH inhibitor treatment was initiated in 32 patients with chronic HF complicated by renal anemia and were followed up for 3 months.

RESULTS

Hematocrit and hemoglobin levels markedly improved 3 months after HIF-PH inhibitor treatment. However, levels of NT-proBNP, which is an indicator of HF, did not decrease considerably. Based on the rate of change in NT-proBNP, we divided the patients into "responder" and "non-responder" groups. The results showed that considerably more patients had a ferritin level of less than 100 ng/mL in the non-responder group at baseline. There were substantially more patients with TSAT of less than 20% in the non-responder group at 1 month after HIF-PH inhibitor treatment. The cut-off values to maximize the predictive power of ferritin level at baseline and TSAT value at 1 month after treatment were 41.8 ng/ml and 20.75. HIF-PH inhibitor treatment can be expected to be effective for improving both anemia and HF if ferritin≥41.8 ng/ml at baseline or TSAT≥20.75 at 1 month after treatment.

Iron-induced kidney cell damage: insights into molecular mechanisms and potential diagnostic significance of urinary FTL

Background: Iron overload can lead to organ and cell injuries. Although the mechanisms of iron-induced cell damage have been extensively studied using various cells, little is known about these processes in kidney cells. Methods: In this study, we first examined the correlation between serum iron levels and kidney function. Subsequently, we investigated the molecular impact of excess iron on kidney cell lines, HEK293T and HK-2. The presence of the upregulated protein was further validated in urine. Results: The results revealed that excess iron caused significant cell death accompanied by morphological changes. Transcriptomic analysis revealed an up-regulation of the ferroptosis pathway during iron treatment. This was confirmed by up-regulation of ferroptosis markers, ferritin light chain (FTL), and prostaglandin-endoperoxide synthase 2 (PTGS2), and down-regulation of acyl-CoA synthetase long-chain family member 4 (ACSL4) and glutathione peroxidase 4 (GPX4) using real-time PCR and Western blotting. In addition, excess iron treatment enhanced protein and lipid oxidation. Supportively, an inverse correlation between urinary FTL protein level and kidney function was observed. Conclusion: These findings suggest that excess iron disrupts cellular homeostasis and affects key proteins involved in kidney cell death. Our study demonstrated that high iron levels caused kidney cell damage. Additionally, urinary FTL might be a useful biomarker to detect kidney damage caused by iron toxicity. Our study also provided insights into the molecular mechanisms of iron-induced kidney injury, discussing several potential targets for future interventions.

Regulation of erythropoiesis: emerging concepts and therapeutic implications

The process of erythropoiesis is complex and involves the transfer of cells from the yolk sac to the fetal hepar and, ultimately, to the bone marrow during embryonic development. Within the bone marrow, erythroid progenitor cells undergo several stages to generate reticulocytes that enter the bloodstream. Erythropoiesis is regulated by various factors, with erythropoietin (EPO) synthesized by the kidney being the promoting factor and hepcidin synthesized by the hepar inhibiting iron mobilization. Transcription factors, such as GATA and KLF, also play a crucial role in erythropoiesis. Disruption of any of these factors can lead to abnormal erythropoiesis, resulting in red cell excess, red cell deficiency, or abnormal morphological function. This review provides a general description of erythropoiesis, as well as its regulation, highlighting the significance of understanding the process for the diagnosis and treatment of various hematological disorders.

FGF23 and SOX9 expression in hemophilic cartilage: In vitro studies of the effects of iron

INTRODUCTION

Clarifying the links between iron and FGF23, SOX9 expression in chondrocytes would be helpful for comprehending articular cartilage degradation pathogenesis in blood-induced arthritis and exploring new protective methods.

AIM

The purpose of this study was to determine iron regulation of fibroblast growth factor 23 (FGF23) and SRY-box 9 (SOX9) in human chondrocytes, an area which is unexplored in blood-induced arthritis cartilage degradation pathogenesis.

METHODS

Expression of FGF23, SOX9, MMP13 and collagen Ⅱ in articular cartilage of patients with osteoarthritis (OA) or haemophilic arthritis (HA) was determined by western blot (WB). Iron induced FGF23 and SOX9 mRNA and protein expression in primary human normal chondrocyte cells (HUM-iCell-s018) was quantifified by qRT-PCR and WB, respectively.

RESULTS

We found that compared with OA patients, the expression of FGF23, MMP13 in articular cartilage of patients with HA was up-regulated, while the expression of SOX9, collagen Ⅱ was down-regulated. Iron induced FGF23 and suppressed SOX9 expression in chondrocytes in a dose-dependent manner.

CONCLUSIONS

These findings demonstrated that iron were involved in hemophilic cartilage lesion directly via changing cartilage phenotype through regulation of FGF23 and SOX9 expression in chondrocytes.

Effect of different hemodialysis modalities on hepcidin clearance in patients undergoing maintenance hemodialysis

INTRODUCTION

Hepcidin is a master regulator of iron utilization and takes part in the pathophysiology of anemia in maintenance hemodialysis (MHD) patients. Hepcidin is a moderate-molecular-weight substance and partially binds to plasma proteins in the circulation, which theoretically might be removed efficiently by hemoperfusion (HP). This study aimed to compare the effect of different dialysis modalities on hepcidin removal and discuss its effect on the iron and anemia status in MHD patients.

MATERIALS AND METHODS

In a longitudinal interventional study of 26 stable MHD patients, the serum hepcidin, β2-microglobulin (β2-MG), and intact parathyroid hormone (iPTH) were measured before and after one treatment session of hemodialysis (HD), hemodiafiltration (HDF), HD + HP, and HDF + HP, separately. One-way analysis of variance (ANOVA) was used to identify the effect of dialysis modalities on the intra-dialysis clearance ratios.

RESULTS

The combined dialysis modalities (HD + HP and HDF + HP) achieved greater clearance ratios of serum hepcidin than HD and HDF alone, HD + HP vs. HD (16 ± 15% vs. 4 ± 13%, p < 0.001), HDF + HP vs. HDF (18 ± 5% vs. 10 ± 13%, p = 0.0036). Similarly, the combined dialysis modalities also performed better than HD and HDF alone in removing β2-MG. There was no significant difference in iPTH clearance among these four modalities, except that HDF + HP achieved a greater clearance ratio than HD. Furthermore, the anemia was improved after the 6-month treatment with regular HD/HDF plus HP, which was indicated by increasing hemoglobin (p = 0.0004) and reduction of erythropoiesis-stimulating agents (ESAs) resistance index (ERI) (p = 0.0431).

CONCLUSIONS

Our findings suggest that the combined dialysis modalities of HD/HDF plus HP could achieve better clearance ratios of hepcidin than HD/HDF alone, thereby, might improve iron utilization, and benefit anemia management in MHD patients. Further studies with larger sample-size patients and longer follow-up duration are still needed.

The influence of blood donation before pregnancy on neonatal birth weight

Objective

To evaluate the effect of blood donation before pregnancy on neonatal birth weight.

Methods

A total of 14996 women with singleton pregnancies at full-term in Ningbo Medical Center Lihuili Hospital and Ningbo Women’s and Children’s Hospital from November 2019 to November 2020 were enrolled in this study. Detailed records of whole blood donation before pregnancy were obtained through Alipay software. The records were classified into three groups: nondonors, low-frequency donors and high-frequency donors according to the total numbers of blood donations in the 3-year period before pregnancy. The demographics and clinical information of the enrolled participants and their fetuses were collected from electronic medical records (EMRs). The effect of blood donations in the 3-year period before pregnancy on neonatal birth weight was analyzed.

Results

There was no significant difference in neonatal birth weight among the three groups (P = 0.373). In line with this, there was no association between the number of blood donations in the 3-year period before pregnancy and neonatal birth weight (β = 14.5; 95% confidence interval [CI]: -3.9, 31.4; P = 0.094) in the bootstrapped multivariate linear regression analysis models, adjusted for maternal age, number of pregnancies, number of deliveries, gestational age, mode of delivery, years of education and blood type in pregnant women. Compared to the nondonors, the risk of fetal macrosomia was higher in both low-frequency donors and all donors (OR: 1.539, 95% CI: 1.058, 2.134, P = 0.016; OR: 1.454, 95% CI: 1.033, 1.952, P = 0.021, respectively), in the bootstrapped binary logistic regression analysis models after adjusting for the variables mentioned above.

Conclusion

Our study showed that maternal blood donation in the 3-year period before pregnancy may not lead to a reduction in neonatal birth weight, but may be associated with the incidence of fetal macrosomia.

[Prevalence of malnutrition and absolute and functional iron deficiency anemia in nondialysis-dependent chronic kidney disease and hemodialysis Algerian patients]

In chronic kidney disease, anemia and malnutrition coupled with inflammation as malnutrition-inflammation complex syndrom are common and considered as morbidity-mortality factors. The link between these two factors has been described at length in the literature highlighting an association of malnutrition with iron deficiency considered itself as one of the causes of anemia in chronic kidney disease (non-dialysis and hemodialysis). Our study aims to know the prevalence of these two factors in a population of chronic kidney disease (non-dialysis and hemodialysis) of Algiers and to highlight the possible associations between them.

PATIENTS AND METHODS

This is a multicentre, cross-sectional and descriptive study carried out over a period of 6months (August 2018 to January 2019). Anemia and malnutrition were assessed by various biological and clinical tools such as the malnutrition inflammation score and the International Society of Renal Nutrition and Metabolism criteria. Statistical tests were performed on the R studio software, considering P<0.05 as a statistically significant value.

RESULTS

Two hundred and nine patients on chronic kidney disease were included (90 non dialysis and 119 hemodialysis). The median age was 70 (IQR=16) for non dialysis and 56 (IQR=16.5) for hemodialysis. The prevalence of anemia was 66.66% (n=60) in non dialysis and 70.58% (n=84) in hemodialysis. Absolute iron deficiency anemia was higher in non dialysis (48.33%; n=29) while functional iron deficiency anemia was higher in hemodialysis (34.52%; n=29). The prevalence of malnutrition by malnutrition inflammation score was relatively low. Only functional iron deficiency anemia was associated with malnutrition.

CONCLUSION

The prevalence of anemia was higher in Algerian chronic kidney disease (non-dialysis and hemodialysis) unlike malnutrition which remains associated with functional iron deficiency anemia.

Association between the blood manganese (Mn) and hemoglobin in patients undergoing maintenance hemodialysis

BACKGROUND AND AIMS

Manganese (Mn) and iron metabolism are closely related. Iron metabolism disorders often lead to anemia in patients undergoing maintenance hemodialysis (MHD). Here, we aimed to investigate the relationship between blood Mn and hemoglobin (Hb) in patients undergoing MHD.

METHODS

Patients undergoing MHD in September 2019 were included in a cross-sectional study. Clinical and demographic data and blood samples were collected before hemodialysis sessions, and blood levels of Mn were measured by inductively coupled plasma mass spectrometry. Both multivariable linear and binary logistic regression analyses were performed to study the relationship between the blood Mn and Hb.

RESULTS

A total of 144 patients undergoing MHD were enrolled in the study. The patients had a mean age of 64.33 ± 13.39 years, median vintage of 33.50 (16.25-57.50) months. Among them, 66 were females (45.8%). The median blood Mn level was 13.55 µg/L (IQR:9.92-17.48). Ninety-nine patients were anemic (68.8%). The mean Hb level was 99.83 ± 19.68 g/L. The patient group with high blood Mn had a high proportion of females, and these patients had high levels of RBC, hemoglobin, Hct, UIBC, serum TCHOL, and serum LDL, yet short dialysis vintage, low prevalence of anemia, low levels of serum ferritin, serum iron, and TSAT. Following adjustment for confounding factors, we found that low blood Mn level was independently associated with lower Hb level and anemia in patients undergoing MHD by multivariate linear and multivariate binary logistic regression, respectively, in different models.

CONCLUSION

Whilst our study showed that high levels of blood Mn were independently associated with high hemoglobin in patients undergoing MHD, further multicenter studies with large sample sizes are still required.

Current Status of Renal Anemia Pharmacotherapy-What Can We Offer Today

Chronic kidney disease (CKD) is one of the fastest-growing major causes of death internationally. Better treatment of CKD and its complications is crucial to reverse this negative trend. Anemia is a frequent complication of CKD and is associated with unfavorable clinical outcomes. It is a devastating complication of progressive kidney disease, that negatively affects also the quality of life. The prevalence of anemia increases in parallel with CKD progression. The aim of this review is to summarize the current knowledge on therapy of renal anemia. Iron therapy, blood transfusions, and erythropoietin stimulating agents are still the mainstay of renal anemia treatment. There are several novel agents on the horizon that might provide therapeutic opportunities in CKD. The potential therapeutic options target the hepcidin–ferroportin axis, which is the master regulator of iron homeostasis, and the BMP-SMAD pathway, which regulates hepcidin expression in the liver. An inhibition of prolyl hydroxylase is a new therapeutic option becoming available for the treatment of anemia in CKD patients. This new class of drugs stimulates the synthesis of endogenous erythropoietin and increases iron availability. We also summarized the effects of prolyl hydroxylase inhibitors on iron parameters, including hepcidin, as their action on the hematological parameters. They could be of particular interest in the out-patient population with CKD and patients with ESA hyporesponsiveness. However, current knowledge is limited and still awaits clinical validation. One should be aware of the potential risks and benefits of novel, sophisticated therapies.

Serum Hepcidin-25 and All-Cause Mortality in Patients Undergoing Maintenance Hemodialysis

Background

Hepcidin plays an important role in iron homeostasis, inhibits intestinal iron absorption and iron release from hepatocytes and macrophages, while its clinical utility remained unclear. This study aimed to investigate the associations between hepcidin-25 and mortality in MHD patients.

Methods

This was a prospective observational cohort of 161 MHD patients, with 2-year follow-up. We investigated the relationships between the variables in our dataset, including serum hepcidin-25, demographic characteristics as well as other clinical parameters.

Results

The median value of baseline serum hepcidin-25 was 31.0 (12.1, 57.3) ng/mL; therefore, the patients were stratified into two groups (low-level hepcidin-25 group, and high-level hepcidin-25 group). The serum iron, serum ferritin, transferrin saturation (TSAT), and hsCRP were higher, pre-dialysis creatinine and albumin were lower, and the scores of health-related qualities of life were worse in the high-level hepcidin-25 group than in the low-level hepcidin-25 group. Maximal information-based nonparametric exploration analysis suggested that serum hepcidin-25 was associated with ferritin, TSAT, and all-cause mortality. The patients with hepcidin-25<31 ng/mL had better survival outcomes than those with hepcidin-25≥31 ng/mL during the 24-month follow-up (Log rank test, P = 0.0017). For per 10ng/mL increase of serum hepcidin-25, the hazard ratio (HR) for all-cause mortality was 1.225 (95% confidence interval [CI]1.085-1.382, P<0.001), which remained significant after multivariate adjustments.

Conclusion

Serum hepcidin-25 was associated with ferritin and TSAT, and could be an independent predictor for all-cause mortality in MHD patients. Further research with larger sample size and longer-term follow-up is still needed.

Serum Hepcidin-25 and Risk of Mortality in Patients on Peritoneal Dialysis

Background: Increased serum hepcidin-25 level is associated with excess mortality in hemodialysis patients. However, there is a dearth of published information about its predictive effect for survival in patients on peritoneal dialysis (PD). The purpose of this study is to evaluate the association of serum hepcidin-25 with the risk of mortality in PD patients. Methods: Serum hepcidin-25 level was measured using an enzyme-linked immunosorbent assay in a prospective cohort study of PD patients with stored serum samples at baseline. Multivariate linear regression model was used to determine clinical characteristics associated with serum hepcidin-25 concentration. We evaluated the relationship between serum hepcidin-25 and all-cause mortality using a Cox proportional hazards model and the relationship between hepcidin-25 and cardiovascular (CV) and infection-related deaths using competing-risks regression models. Results: In total, 513 PD patients were included in this study. The median serum hepcidin-25 level was 40.9 (17.9-85.9) ng/mL. Body mass index and serum ferritin were positively correlated with serum hepcidin-25 levels. During a median follow-up period of 64.1 months, 122 (24%) patients died, including 61 (50%) CV deaths and 32 (26%) infection-related deaths. In multivariable analysis, patients with the highest tertile of serum hepcidin-25 had a greater risk of all-cause [adjusted hazard ratio (aHR) 1.85, 95% confidence interval (95%CI), 1.14 to 3.00, P = 0.013] and infection-related mortality (adjusted subdistribution hazard ratio [aSHR], 2.61; 95%CI, 1.01 to 6.76, P = 0.049) when compared with those in the second tertile. However, no significant relationship was observed between serum hepcidin-25 and CV mortality. Conclusions: Higher baseline serum hepcidin-25 level was associated with increased risk for all-cause and infection-related mortality in PD patients.

Ironing out mechanisms of iron homeostasis and disorders of iron deficiency

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