Is hepcidin-25 a predictor of atherosclerosis in hemodialysis patients?

Association between Iron Status and Survival in Patients on Chronic Hemodialysis

The aim of this study was to evaluate survival rates according to iron status in patients undergoing maintenance hemodialysis (HD). Thus, the National HD Quality Assessment Program dataset and claims data were used for analysis (n = 42,390). The patients were divided into four groups according to their transferrin saturation rate and serum ferritin levels: Group 1 (n = 34,539, normal iron status); Group 2 (n = 4476, absolute iron deficiency); Group 3 (n = 1719, functional iron deficiency); Group 4 (n = 1656, high iron status). Using univariate and multivariable analyses, Group 1 outperformed the three other groups in terms of patient survival. Using univariate analysis, although Group 2 showed a favorable trend in patient survival rates compared with Groups 3 and 4, the statistical significance was weak. Group 3 exhibited similar patient survival rates to Group 4. Using multivariable Cox regression analysis, Group 2 had similar patient survival rates to Group 3. Subgroup analyses according to sex, diabetic status, hemoglobin level ≥ 10 g/dL, and serum albumin levels ≥ 3.5 g/dL indicated similar trends to those of the total cohort. However, subgroup analysis based on patients with a hemoglobin level < 10 g/dL or serum albumin levels < 3.5 g/dL showed a weak statistical significant difference compared with those with hemoglobin level ≥ 10 g/dL, or serum albumin levels ≥ 3.5 g/dL. In addition, the survival difference between Group 4 and other groups was greater in old patients than in young ones. Patients with a normal iron status had the highest survival rates. Patient survival rates were similar or differed only modestly among the groups with abnormal iron status. In addition, most subgroup analyses revealed similar trends to those according to the total cohort. However, subgroup analyses based on age, hemoglobin, or serum albumin levels showed different trends.

Iron Metabolism Markers and Lower Extremity Arterial Disease in People with Type 2 Diabetes

OBJECTIVE

To determine the levels of serum iron, ferritin, total iron-binding capacity, and hepcidin in patients with type 2 diabetes mellitus (T2DM), and to elucidate the relationship of these biomarkers with lower extremity arterial disease (LEAD).

METHODS

Three hundred fifteen patients with T2DM were selected for the study and divided into non-LEAD (n = 119) and LEAD groups (n=196) based on the ankle-brachial index (ABI) results. Demographic data and clinical test results were collected from all patients. Serum iron, ferritin, total iron-binding capacity, and hepcidin levels were measured, and the transferrin saturation was calculated.

RESULTS

Hepcidin levels were substantially higher in the LEAD group (19.17 ± 8.66 ng/mL) than the non-LEAD group (15.44±7.55 ng/mL, P < 0.001), and there was a negative correlation between the ABI and serum lecithin level (r = -0.349, P < 0.001). There were no other correlations with the other iron metabolism indicators. The results of dichotomous logistic regression with LEAD as the dependent variable revealed that smoking history (OR = 4.442, P = 0.008), hypertension history (OR = 3.721, P = 0.006), cardiovascular disease history (OR = 11.126, P < 0.001), diabetes duration (OR = 1.305, P < 0.001), age (OR = 1.056, P = 0.021), hs-CRP level (OR = 1.376, P = 0.002), HbA1c concentration (OR = 1.394, P = 0.001), and hepcidin level (OR = 1.097, P = 0.003) were independent risk factors for LEAD in T2DM patients.

CONCLUSION

Serum hepcidin levels were elevated in the LEAD group compared with the non-LEAD group, and elevated hepcidin levels were associated with the development of LEAD in T2DM patients, suggesting that hepcidin may be involved in the occurrence and development of LEAD in T2DM patients.

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.

The Study of the Aorta Metallomics in the Context of Atherosclerosis

Atherosclerosis is a multifactorial disease, for which the etiology is so complex that we are currently unable to prevent it and effectively lower the statistics on mortality from cardiovascular diseases. Parallel to modern analyses in molecular biology and biochemistry, we want to carry out analyses at the level of micro- and macroelements in order to discover the interdependencies between elements during atherogenesis. In this work, we used the Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) to determine the content of calcium, magnesium, iron, copper, chromium, zinc, manganese, cadmium, lead, and zinc in the aorta sections of people who died a sudden death. We also estimated the content of metalloenzymes MMP-9, NOS-3, and SOD-2 using the immunohistochemical method. It was observed that with the age of the patient, the calcium content of the artery increased, while the content of copper and iron decreased. Very high correlations (correlation coefficient above 0.8) were observed for pairs of parameters in women: Mn–Ca, Fe–Cu, and Ca–Cd, and in men: Mn–Zn. The degree of atherosclerosis negatively correlated with magnesium and with cadmium. Chromium inhibited absorption of essential trace elements such as Cu and Fe due to its content being above the quantification threshold only if Cu and Fe were lower. Moreover, we discussed how to design research for the future in order to learn more about the pathomechanism of atherosclerosis and the effect of taking dietary supplements on the prevalence of cardiovascular diseases.

Balance of cardiac and systemic hepcidin and its role in heart physiology and pathology

Hepcidin is the main regulator of iron metabolism in tissues. Its serum levels are mostly correlated with the levels of hepcidin expression from the liver, but local hepcidin can be important for the physiology of other organs as well. There is an increasing evidence that this is the case with cardiac hepcidin. This has been confirmed by studies with models of ischemic heart disease and other heart pathologies. In this review the discussion dissects the role of cardiac hepcidin in cellular homeostasis. This review is complemented with examination of the role of systemic hepcidin in heart disease and its use as a biochemical marker. The relationship between systemic vs local hepcidin in the heart is important because it can help us understand how the fine balance between the actions of two hepcidins affects heart function. Manipulating the axis systemic/cardiac hepcidin could serve as a new therapeutic strategy in heart diseases.

Relation between high serum hepcidin-25 level and subclinical atherosclerosis and cardiovascular mortality in hemodialysis patients

OBJECTIVE

In hemodialysis (HD) patients, cardiovascular disease (CVD) is the major cause of mortality and morbidity. In atherosclerotic diseases, iron gets accumulated in the arterial wall. Hepcidin is an important hormone in iron metabolism. Furthermore, hepcidin is associated with atherosclerotic disease. Therefore, this study aims to investigate the relation of serum hepcidin-25 (SH-25) and sub-clinic atherosclerosis measured by carotid intima-media thickness (CIMT) and mortality in HD patients.

METHODS

We enrolled 82 HD patients in a cross-control study. We measured SH-25 using ELISA kit and CIMT using high-resolution real-time ultrasonography. After 4 years of first assessment, we investigated the relation between all-cause and cardiovascular mortality and SH-25 and CIMT.

RESULTS

Two patients were excluded because of renal transplantation. The survivors were younger (53.7±15.1 vs. 65.2±15.5; p<0.05) and CIMT was lower (0.83±0.2 vs. 0.95±0.2; p<0.05); however, there was no significant difference in SH-25 levels between the groups (29.1±13 vs. 32.4±22.4; p=0.767). The patients who died of CVD were significantly older (63.7±16.1 vs. 53.7±15.1; p<0.05) and had significantly higher CIMT (0.94±0.2 vs. 83±0.2; p<0.05). The SH-25 levels were statistically significantly higher in patients who died of CVD (40.3±25 vs. 29.1±13; p<0.05). Linear regression analysis showed a positive correlation between CIMT and SH-25 in the study population and in those who died from CVD (r=0.41; p<0.05 and r=0.606; p<0.05, respectively).

CONCLUSION

This study suggests that hepcidin is effective in cardiovascular mortality and pathophysiology of subclinical atherosclerosis in HD patients.

Association between baseline serum hepcidin levels and infection in kidney transplant recipients: Potential role for iron overload

BACKGROUND

The liver-synthesized peptide hepcidin is a key regulator of iron metabolism and correlates with total iron stores. We analyzed the association between pre-transplant hepcidin-25 levels and infection after kidney transplantation (KT).

METHODS

Serum hepcidin-25 levels were measured at baseline by high-sensitivity ELISA in 91 patients undergoing KT at our institution between December 2011 and March 2013. The impact of this biomarker on the incidence of post-transplant infection (excluding lower urinary tract infection) during the first year was assessed by Cox regression.

RESULTS

Mean hepcidin-25 level was 82.3 ± 67.4 ng/mL and strongly correlated with serum ferritin (Spearman's rho = 0.703; P < .001). There were no significant differences in hepcidin-25 levels between patients with or without overall infection (96.4 ± 67.5 vs 72.6 ± 66.7 ng/mL; P = .101). Such difference was evident for opportunistic (128.9 ± 75.0 vs 73.0 ± 62.3 ng/mL; P = .003) and, to a lesser extent, surgical-site infection (107.5 ± 73.3 vs 76.5 ± 65.2 ng/mL; P = .087). Patients with hepcidin-25 levels ≥72.5 ng/mL had higher 12-month cumulative incidence of overall infection (51.2% vs 29.2%; P = .032). After multivariate adjustment, hepcidin-25 ≥72.5 ng/mL acted as an independent risk factor for overall (adjusted hazard ratio [aHR] 3.86; 95% confidence interval [CI] 1.49-9.96; P = .005) and opportunistic infection (aHR 4.32; 95% CI 1.18-15.75; P = .027).

CONCLUSION

Elevated baseline serum hepcidin-25 levels were associated with increased risk of infection after KT, suggesting a role for iron overload in the individual susceptibility to post-transplant infection.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

A single dialysis session of hemodiafiltration with sorbent-regenerated endogenous ultrafiltrate reinfusion (HFR) removes hepcidin more efficiently than bicarbonate hemodialysis: a new approach to containing hepcidin burden in dialysis patients?

BACKGROUND

Most hemodialysis patients have high Hepcidin-25 levels, which may be involved in the pathogenesis of several uremic complications related to an altered iron biology. The hemodialysis procedure itself can influence Hepcidin-25 levels by removing Hepcidin-25 and maybe stimulating its production due to a pro-inflammatory effect.

METHODS

To assess the relationship between dialysis-related inflammation and intradialysis changes in Hepcidin-25, we performed a crossover trial in 28 hemodialysis patients to compare the effects on serum levels of Hepcidin-25 and inflammatory markers activated during dialysis [Tumor Necrosis Factor-α (TNF-α), Interleukin-6, C-reactive protein (CRP), Pentraxin-3] of a single dialysis session using a technique capable of reducing inflammation, HFR (Hemo Filtrate Reinfusion: a hemodiafiltration system combining convection, diffusion and adsorption) or bicarbonate-dialysis using either the same low-flux membrane as in the diffusion stage of HFR (LFBD) or a high-flux membrane (HFBD).

RESULTS

HFR achieved a greater reduction in Hepcidin-25 levels than both LFBD [-72% (95% CI: -11 to -133), p = 0.022] and HFBD [-137% (95% CI: -2 to -272), p = 0.047], conceivably due to both a greater removal (because of its convective/adsorptive component) and a lower inflammation-related Hepcidin-25 production. HFR also led to a greater decrease in TNF-α than LFBD [-277% (95% CI: -59 to -494), p = 0.014], while the two methods induced similar changes in Interleukin-6, CRP and Pentraxin-3 levels.

CONCLUSIONS

Our findings suggest that a single bicarbonate-dialysis session can upregulate Hepcidin-25 synthesis and that HFR can fully overcome this effect, enabling a greater Hepcidin-25 removal during dialysis. Adequately-designed studies are needed, however, to establish whether the beneficial effect of HFR emerging from our study could reduce Hepcidin-25 (and TNF-α) burden and improve clinically-relevant outcomes.

TRIAL REGISTRATION

ISRCTN15957905.