High Ferritin Is Not Needed in Hemodialysis Patients: A Retrospective Study of Total Body Iron and Oral Iron Replacement Therapy

In vivo iron levels can be adjusted through intestinal iron absorption to be maintained at a suitable level; however, optimal iron levels in hemodialysis (HD) patients are unclear. In this study, we investigated total body iron (TBI), calculated as the sum of red blood cell (RBC) iron and iron stores, during courses of low-dose oral iron replacement therapy, and evaluated in vivo iron sufficiency and its indicators in HD patients. We analyzed data on 105 courses of low-dose iron replacement therapy administered to 83 patients on maintenance HD over 7 months. We evaluated changes in TBI, RBC iron, and iron stores from the initiation of treatment to month 7 in two groups of patients, namely, iron-therapy responders and non-responders. TBI showed significant increases until month 4 and plateaued thereafter in iron-therapy responders, and tended to increase and then reached a similar plateau in non-responders (month 7: 1900 ± 447 vs. 1900 ± 408 mg). Steady-state TBI was strongly correlated with body surface area (y = 1628.6x - 791.91, R2 = 0.88, p < 0.001). We observed constant TBI during oral iron replacement therapy suggesting the activation of a "mucosal block". The results suggest that body surface area has utility for estimating the required TBI with regression equations.

Oral Iron Absorption of Ferric Citrate Hydrate and Hepcidin-25 in Hemodialysis Patients: A Prospective, Multicenter, Observational Riona-Oral Iron Absorption Trial

Oral ferric citrate hydrate (FCH) is effective for iron deficiencies in hemodialysis patients; however, how iron balance in the body affects iron absorption in the intestinal tract remains unclear. This prospective observational study (Riona-Oral Iron Absorption Trial, R-OIAT, UMIN 000031406) was conducted at 42 hemodialysis centers in Japan, wherein 268 hemodialysis patients without inflammation were enrolled and treated with a fixed amount of FCH for 6 months. We assessed the predictive value of hepcidin-25 for iron absorption and iron shift between ferritin (FTN) and red blood cells (RBCs) following FCH therapy. Serum iron changes at 2 h (ΔFe2h) after FCH ingestion were evaluated as iron absorption. The primary outcome was the quantitative delineation of iron variables with respect to ΔFe2h, and the secondary outcome was the description of the predictors of the body's iron balance. Generalized estimating equations (GEEs) were used to identify the determinants of iron absorption during each phase of FCH treatment. ΔFe2h increased when hepcidin-25 and TSAT decreased (-0.459, -0.643 to -0.276, p = 0.000; -0.648, -1.099 to -0.197, p = 0.005, respectively) in GEEs. FTN increased when RBCs decreased (-1.392, -1.749 to -1.035, p = 0.000) and hepcidin-25 increased (0.297, 0.239 to 0.355, p = 0.000). Limiting erythropoiesis to maintain hemoglobin levels induces RBC reduction in hemodialysis patients, resulting in increased hepcidin-25 and FTN levels. Hepcidin-25 production may prompt an iron shift from RBC iron to FTN iron, inhibiting iron absorption even with continued FCH intake.

Changes of biomarkers for erythropoiesis, iron metabolism, and FGF23 by supplementation with roxadustat in patients on hemodialysis

This study aimed to confirm changes in biomarkers of erythropoiesis and iron metabolism and serum fibroblast growth factor 23 (FGF-23) during darbepoetin-α treatment and then switching to the hypoxia-inducible factor prolyl hydroxylase inhibitor roxadustat. A total of 28 patients on hemodialysis who received weekly doses of darbepoetin-α were switched to roxadustat. Biomarkers for erythropoiesis and iron metabolism and intact and C-terminal FGF-23 were measured in blood samples collected before the HD session on days - 7 (darbepoetin-α injection), - 4, and - 2, and days 0 (switch to roxadustat treatment, three times weekly), 3, 5, 7, 14, 21, and 28. Erythropoietin and erythroferrone levels were elevated on day - 4 by darbepoetin-α injection and decreased to baseline levels at day 0. Levels of erythropoietin were not significantly increased by roxadustat supplementation, but erythroferrone levels were continuously elevated, similar to darbepoetin-α treatment. Hepcidin-25 and total iron binding capacity were significantly decreased or increased in patients treated with roxadustat compared with darbepoetin-α. Changes of intact and C-terminal FGF-23 levels were parallel to changes of phosphate levels during roxadustat treatment. However, the actual and percentage changes of intact FGF-23 and C-terminal FGF-23 in patients with low ferritin levels were greater than those in patients with high ferritin levels. Roxadustat might stimulate erythropoiesis by increasing iron usage through hepcidin-25, which was suppressed by erythroferrone in the physiological erythropoietin condition. Changes of intact FGF-23 and C-terminal FGF-23 levels might be affected by roxadustat in patients on hemodialysis, especially those with a low-iron condition.

Threshold of Serum Ferritin to Discriminate against Those at Greater Risk of Platelet Increase during Treatment with Hypoxia-Inducible Factor Prolyl Hydroxylase Domain Inhibitor

INTRODUCTION

Hypoxia-inducible factor prolyl hydroxylase domain inhibitors (HIF-PHI) are a new treatment for renal anemia. HIF-PHI is believed to increase iron usage to improve availability of iron for erythropoiesis. Therefore, there is concern that HIF-PHI might be prone to iron deficiency and that thrombosis might be induced by increased platelet and transferrin levels due to this iron deficiency.

METHODS

Relationship of iron-related factors with platelet count (PLT), and total iron-binding capacity (TIBC; which reflects the transferrin level) were examined in 29 patients who were treated with darbepoetin alfa (DA) and then switched to roxadustat (Rox). To determine how changes in PLT and TIBC related to changes in iron-related factors, univariable and multivariable linear regression models were applied. To examine what iron-related factors on Day 0 influenced change in PLT, we used receiver operating characteristic curves (ROC) and logistic regression analysis for a rate of change in PLT ≤ 0% as the endpoint. Logistic regression analysis was performed with the reference group having serum ferritin (s-ft) or TSAT below the corresponding cutoff value (low vs high).

RESULTS

Multivariable analysis showed significant positive correlations between the rate of change in PLT and the change in serum ferritin (s-ft) and red blood cells (RBC) count [β-coefficients; 0.40 (95% confidence interval [CI]: 0.17 to 0.62), P = 0.001], [β-coefficients; 30.45 (95% CI: 10.90 to 50.00), P = 0.004]. The rate of change in TIBC was significantly positively correlated with only the change in RBC count. The ROC showed a significant cutoff value for s-ft of 77.2 ng/mL (sensitivity 63.6%, specificity 83.3%, area under the curve 0.76, 95% CI 0.55-0.96). Multivariable logistic regression also showed that only high s-ft was significantly elevated (9.46, 95% CI 1.42-63.30, P = 0.020).

CONCLUSIONS

This study showed that changes in PLT were correlated with s-ft and amount of hematopoiesis. This suggests that an increase in PLT due to iron levels is less likely when s-ft is 77.2 ng/mL or higher at the time of switching from DA to Rox. In contrast, TIBC was only related to hematopoiesis in these patients. Control of s-ft before initation of HIF-PHI treatment and gradual hematopoiesis might reduce the risk of thrombosis when switching from erythropoiesis-stimulating agents (ESAs) to HIF-PHI.

Gentle, Massage-like, Head Stroking Provokes Salivary Oxytocin Release

CONTEXT

The evidence is growing that oxytocin (OXT), a hypothalamic hormone, can induce parturition and lactation, modulate affiliative behavior, and regulate stress and energy metabolism. Although the physiological effects of massage aren't fully understood, massage may affect OXT release and facilitate adaptive responses to stressors.

OBJECTIVES

This study intended to examine the effects of gentle, massage-like head, stroking to determine whether it could have a direct influence on the release of OXT.

DESIGN

The research team performed a preliminary study.

SETTING

The study was conducted at Kanazawa Medical University in Kahoku and Mizuho Hospital, Tsubata, Ishikawa, Japan.

PARTICIPANTS

Participants were 14 volunteers from Mizuho Hospital.

INTERVENTION

The 14 recruited participants were assigned to the massage group and received gentle, massage-like, head stroking, which lasted 60 minutes. Seven of those participants were randomly recruited to become a control group that rested only, without massage, on a different day than the massage occurred.

OUTCOME MEASURES

Participants' saliva for both groups was drawn at baseline and postintervention on the different days. Salivary OXT was assayed using a highly sensitive chemiluminescence immunoassay. Analyses were performed at baseline before the intervention and postintervention.

RESULTS

The OXT secretion increased significantly in the massage group unlike in the rest group, which had no change.

CONCLUSIONS

Gentle, massage-like, head stroking is an effective method of releasing endogenous OXT. These findings open up the possibility of using endogenous OXT as an adjunct therapy in both clinical and research settings.

Comprehensive analysis of protein-expression changes specific to immunoglobulin G4-related disease

BACKGROUND AND AIMS

Immunoglobulin 4 (IgG4)-related disease (IgG4-RD) is a lymphoproliferative disorder characterized by elevated serum IgG4 levels and tissue infiltration of IgG4-positive plasma cells. We analyzed the serum proteins, whose levels varied based on the disease state and treatment.

MATERIALS AND METHODS

Serum proteins from patients with IgG4-related disease and healthy subjects were resolved using two-dimensional electrophoresis, silver-stained, and scanned. Alternatively, the proteins were labeled with Cy2, Cy3, and Cy5 before electrophoresis. The proteins, whose expression differed significantly between patients and healthy individuals, and between before and after steroid treatment, were identified and validated using enzyme-linked immunosorbent assays.

RESULTS

Pre-treatment sera from patients with IgG4-related disease was characterized by increased levels of immunoglobulins such as IgG1, IgG4; inflammatory factors such as α-1 antitrypsin (A1AT); and proteins associated with immune system regulation such as clusterin and leucine-rich α-2-glycoprotein (LRG-1). The serum levels of A1AT, LRG-1 and clusterin, during treatment with prednisolone for up to 12 months revealed that LRG-1 levels were halved after 1 month of treatment, comparable to those in healthy subjects; LRG-1 levels remained normal until the end of treatment.

CONCLUSION

LRG-1 could serve as a novel biomarker of IgG4-related diseases.

Protective Effects of Collagen Tripeptides in Human Aortic Endothelial Cells by Restoring ROS-Induced Transcriptional Repression

Collagen tripeptide (CTP) is defined as a functional food material derived from collagenase digests of type I collagen and contains a high concentration of tripeptides with a Gly-X-Y sequence. CTP has several biological effects, including the acceleration of fracture healing, ameliorating osteoarthritis, and improving dryness and photoaging of the skin. Recently, an antiatherosclerotic effect of CTP has been reported, although its molecular mechanism is yet to be determined. In this study, we examined the effects of CTP on primary cultured human aortic endothelial cells (HAECs) under oxidative stress, because oxidative endothelial dysfunction is a trigger of atherosclerosis. DNA microarray and RT-qPCR analyses showed that CTP treatment recovered the downregulated expression of several genes, including the interleukin-3 receptor subunit alpha (IL3RA), which were suppressed by reactive oxygen species (ROS) treatment in HAECs. Furthermore, IL3RA knockdown significantly decreased the viability of HAECs compared with control cells. RT-qPCR analysis also showed that solute carrier 15 family peptide transporters, which are involved in CTP absorption into cells, were expressed in HAECs at levels more than comparable to those of a CTP-responsive human osteoblastic cell line. These results indicated that CTP exerts a protective effect for HAECs, at least in part, by regulating the recovery of ROS-induced transcriptional repression.

Hypoxia-inducible factor prolyl hydroxylase domain inhibitor may maintain hemoglobin synthesis at lower serum ferritin and transferrin saturation levels than darbepoetin alfa

Background

Hypoxia-inducible factor (HIF) prolyl hydroxylase domain inhibitors, which have recently become clinically available for treating renal anemia, are attracting attention for their novel mechanisms of action.

Methods

Relationships of reticulocyte hemoglobin content (CHr), which reflects recent Hb synthesis, with serum ferritin (s-ft) and transferrin saturation (TSAT) were examined in 30 patients on hemodialysis after switching from darbepoetin alfa (DA) to roxadustat (Rox). Iron deficiency was defined as CHr < 32.0 pg. Cutoff values of s-ft and TSAT were determined using receiver operating characteristic curves for the endpoint CHr ≥ 32.0 pg. Logistic analysis was performed with the reference group having s-ft or TSAT below the corresponding cutoff value (low vs high).

Results

With the endpoint CHr ≥ 32.0 pg on Day 0, cutoff values for s-ft and TSAT were respectively 49.7 ng/mL and 21.6% on Day 0 and 35.5 ng/mL and 16.2% on Day 28. With the endpoint CHr ≥ 32.0 pg on Day 28, cutoff values for s-ft and TSAT on Day 0 were 81.6 ng/mL and 23.9%, respectively. According to multivariable logistic analysis, the odds ratios of CHr ≥ 32.0 pg on Day 0 were significantly higher for high TSAT on Day 0 [34.7 (95% CI 2.42–131.0), p<0.003] and Day 28 [24.8 (95% CI 2.75–224.0), p = 0.004]. There were no significant differences by s-ft. Odd ratios of CHr ≥ 32.0 pg on Day 28 were also significantly higher for high s-ft on Day 0 [16.0 (95% CI 1.57–163.0), p = 0.019] and high TSAT on Day 0 [13.5 (95% CI 1.24–147.0), p<0.033].

Conclusions

Our results suggest Hb synthesis was maintained with lower TSAT and s-ft during Rox therapy compared with DA therapy. To avoid iron deficiency during the 4 weeks after switching DA to Rox, ideal s-ft and TSAT levels before the switch are 81.6 ng/mL and 23.9%, respectively.

Optimizing hepcidin measurement with a proficiency test framework and standardization improvement

Objectives

Hepcidin measurement advances insights in pathophysiology, diagnosis, and treatment of iron disorders, but requires analytically sound and standardized measurement procedures (MPs). Recent development of a two-level secondary reference material (sRM) for hepcidin assays allows worldwide standardization. However, no proficiency testing (PT) schemes to ensure external quality assurance (EQA) exist and the absence of a high calibrator in the sRM set precludes optimal standardization.

Methods

We developed a pilot PT together with the Dutch EQA organization Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek (SKML) that included 16 international hepcidin MPs. The design included 12 human serum samples that allowed us to evaluate accuracy, linearity, precision and standardization potential. We manufactured, value-assigned, and validated a high-level calibrator in a similar manner to the existing low- and middle-level sRM.

Results

The pilot PT confirmed logistical feasibility of an annual scheme. Most MPs demonstrated linearity (R2>0.99) and precision (duplicate CV>12.2%), although the need for EQA was shown by large variability in accuracy. The high-level calibrator proved effective, reducing the inter-assay CV from 42.0% (unstandardized) to 14.0%, compared to 17.6% with the two-leveled set. The calibrator passed international homogeneity criteria and was assigned a value of 9.07±0.24 nmol/L.

Conclusions

We established a framework for future PT to enable laboratory accreditation, which is essential to ensure quality of hepcidin measurement and its use in patient care. Additionally, we showed optimized standardization is possible by extending the current sRM with a third high calibrator, although international implementation of the sRM is a prerequisite for its success.

The target hemoglobin content values of reticulocytes for efficient anemia improvement are achieved by low ferritin levels and moderate transferrin saturation: a retrospective observational study

Objectives: The optimal iron level in hemodialysis (HD) patients remains unclear. The hemoglobin content of reticulocytes (CHr) is a sensitive indicator of iron used for hematopoiesis. To identify the optimal iron content for HD patients, we investigated the relation between CHr levels and iron status, as well as the levels of hepcidin, a main regulator of iron metabolism.Methods: This study enrolled 181 HD outpatients treated with recombinant human erythropoietin (rHuEPO). A sensitivity analysis, using a generalized linear regression model that included the interaction term, was applied to determine the correlations between levels of CHr and those of serum ferritin (s-ft), transferrin saturation (TSAT), and hepcidin.Results: The greatest changes in correlation coefficients for levels of s-ft and TSAT with CHr levels indicated optimal cut-off points of 50 ng/mL (≤50 ng/mL, r = 0.47 vs >50 ng/mL, r = 0.22) and 24% (≤24%, r = 0.58 vs >24%, r = 0.08), respectively. The correlation coefficient for levels of CHr and hepcidin showed that the optimal lower and upper cut-off points were 20 ng/mL (≤20 ng/mL, r = 0.52 vs >20 ng/mL, r = -0.01) and 70 ng/mL (≤70 ng/mL, r = 0.36 vs >70 ng/mL, r = -0.45), respectively.Discussion: This study indicates that the amount of iron in HD patients is sufficient for hematopoiesis under conditions of low s-ft and moderate TSAT levels. High levels of hepcidin could induce negative iron metabolism in hematopoiesis.Conclusion: Therefore, controlling hepcidin levels to within approximately 20-70 ng/mL may prevent iron deficiency and reduced Hb synthesis, and may thus facilitate effective iron utilization in hematopoiesis.

Erythropoiesis stimulating agents are associated with serum fibroblast growth factor 23 metabolism in patients on hemodialysis

Background

This study aimed to determine associations among short- and long-acting erythropoiesis stimulating agents (ESAs), changes in serum fibroblast growth factor 23 (FGF23) and biomarkers of iron metabolism.

Methods

Among 108 patients on hemodialysis (HD), 44 received every 2 weeks or monthly doses of continuous erythropoiesis receptor activator (CERA), 31 received weekly doses of darbepoetin-α, 24 received three doses per week of epoetin-β and 9 were not treated with an ESA. Intact and C-terminal FGF23 and transferrin saturation (TSAT), ferritin, erythroferrone and hepcidin 25 were measured in blood samples collected before the HD session at the end of the dialysis week (baseline, Day 0) and on Days 3, 5, 7 and 14 thereafter.

Results

Levels of ferritin, hepcidin 25 and erythroferrone as well as TSAT were significantly decreased or elevated in patients treated with CERA compared with other types of ESAs. Levels of C-terminal FGF23 increased in all groups during the observation period. Levels of intact FGF23 and ratios of intact FGF23 to C-terminal FGF23 gradually decreased between Days 3 and 7 in the CERA but not in the other groups. Multivariate models associated changes in hepcidin 25 and phosphate with those of intact FGF23.

Conclusion

The long-acting ESA CERA might influence levels of intact FGF23 by increasing FGF23 cleavage in patients on HD in association with prolonged hepcidin 25 suppression.

Differential Impacts of Intravenous Iron Administration and Iron-Containing Phosphate Binders on Serum Intact Fibroblast Growth Factor 23 Levels

Aims: This study assessed the impact of iron administration on serum fibroblast growth factor 23 (FGF23) levels. Methods: Of 123 hemodialysis (HD) patients treated with erythropoiesis-stimulating agents, 22 received once-weekly intravenous iron and 17 received daily oral iron with iron-containing phosphate binders. Intact FGF23 and biomarkers of iron metabolism were measured from blood samples drawn before each HD session, at baseline and on days 3, 5, 7, and 14. Results: Phosphate levels did not differ among the 3 groups during the 14-day period. Ferritin levels were significantly increased in both iron treatment groups compared with the non-iron treatment group, but changes in transferrin saturation levels were similar in the intravenous iron and non-iron groups. However, intact FGF23 levels were continuously higher in the intravenous iron group than those in the other groups. Conclusion: Intravenous iron administration may influence intact FGF23 levels in HD patients independently of phosphate and iron metabolism.

Low levels of serum ferritin and moderate transferrin saturation lead to adequate hemoglobin levels in hemodialysis patients, retrospective observational study

Background

Optimal iron levels in patients on hemodialysis are currently unknown, and a higher level than that for the healthy population is usually set for such patients considering the use of erythropoiesis-stimulating agents or the occurrence of chronic inflammation. However, excessive iron causes oxidative stress and impairment of its utilization by cells. Therefore we investigated the relationship between hemoglobin (Hb) level and iron status in hemodialysis patients to identify the optimal iron levels for patients undergoing hemodialysis.

Methods

A total of 208 outpatients on maintenance hemodialysis were followed up between July 2006 and June 2007. Men accounted for 64.9% cases [mean age, 59.3 ± 13.1 years and median dialysis history, 7.7 (3.6–13.2) years], and diabetic nephropathy accounted for 25.0% cases. Hemoglobin level was measured twice a month and serum ferritin, serum iron, and total iron-binding capacity were measured once a month. The doses of recombinant human erythropoietin and low-dose iron supplement were adjusted to maintain a hemoglobin level of 10–11 g/dL, according to the guidelines of the Japanese Society for Dialysis Therapy. Hepcidin was measured at baseline. Using the mean values for 1-year period, the relationships among hemoglobin, serum ferritin levels, and transferrin saturation levels were investigated based on a receiver operating characteristic curve and a logistic regression model. In addition, the correlations among serum ferritin, transferrin saturation, and hepcidin levels were analyzed by Pearson product—moment correlation coefficient and linear regression model.

Results

By receiver operating characteristic curve, the cutoff point of serum ferritin and transferrin saturation levels with a hemoglobin ≥10 g/dL showed <90 ng/mL (sensitivity: 69.1%, specificity: 72.1%, p < 0.001) and ≥20% (sensitivity: 77.6%, specificity: 48.8%, p = 0.302).

Upon logistic regression model analysis with a hemoglobin ≥10 g/dL as the endpoint, the analysis of odds ratios relative to a group with serum ferritin ≥90 ng/mL and transferrin saturation <20% revealed that the group with serum ferritin <90 ng/mL and transferrin saturation ≥20% had the highest ratio: 46.75 (95% confidence interval: 10.89–200.70, p < 0.001). In Pearson product—moment correlation coefficient, hepcidin showed a strong positive correlation with serum ferritin [r = 0.78 (95% confidence interval: 0.72–0.83, p < 0.001)] and a weak positive correlation with transferrin saturation [r = 0.18 (95% confidence interval: 0.04–0.31, p = 0.010)]. In the multivariable analyses of the linear regression model, a positive relationship was shown between hepcidin and serum ferritin [β-coefficient of 0.30 (95% confidence interval: 0.27–0.34, p < 0.001)]; however, no relationship was shown with transferrin saturation [β-coefficient of 0.09 (95% confidence interval: −0.31–0.49, p = 0.660)].

Conclusions

In this study, the iron status of serum ferritin <90 ng/mL and transferrin saturation ≥20% was optimal in hemodialysis patients receiving recombinant human erythropoietin for anemia therapy. This result indicates that the threshold values for the optimal iron status may be lower than those currently recommended in iron-level management guideline.

Iron-heme-Bach1 axis is involved in erythroblast adaptation to iron deficiency

Iron plays the central role in oxygen transport by erythrocytes as a constituent of heme and hemoglobin. The importance of iron and heme is also to be found in their regulatory roles during erythroblast maturation. The transcription factor Bach1 may be involved in their regulatory roles since it is deactivated by direct binding of heme. To address whether Bach1 is involved in the responses of erythroblasts to iron status, low iron conditions that induced severe iron deficiency in mice were established. Under iron deficiency, extensive gene expression changes and mitophagy disorder were induced during maturation of erythroblasts. Bach1^−/− mice showed more severe iron deficiency anemia in the developmental phase of mice and a retarded recovery once iron was replenished when compared with wild-type mice. In the absence of Bach1, the expression of globin genes and Hmox1 (encoding heme oxygenase-1) was de-repressed in erythroblasts under iron deficiency, suggesting that Bach1 represses these genes in erythroblasts under iron deficiency to balance the levels of heme and globin. Moreover, an increase in genome-wide DNA methylation was observed in erythroblasts of Bach1^−/− mice under iron deficiency. These findings reveal the principle role of iron as a regulator of gene expression in erythroblast maturation and suggest that the iron-heme-Bach1 axis is important for a proper adaptation of erythroblast to iron deficiency to avoid toxic aggregates of non-heme globin.

High pretransplant hepcidin levels are associated with poor overall survival and delayed platelet engraftment after allogeneic hematopoietic stem cell transplantation

Iron overload is considered a risk factor for mortality in patients with hematopoietic malignancies. Hepcidin is a key regulator of systemic iron balance. We previously reported dynamic changes of serum hepcidin‐25 levels in patients with hematologic malignancies after allogeneic hematopoietic stem cell transplantation (allo‐HSCT). In this study, we retrospectively analyzed the association of pretransplant hepcidin‐25 levels with overall survival (OS), engraftment, and other clinical outcomes of allo‐HSCT in patients with hematologic malignancies. A total of 166 patients were divided into two groups depending on their pretransplant serum hepcidin‐25 levels; their median age was 49.5 years, and the median follow‐up time was 46.8 months. At 3 years, the patients in the high‐hepcidin group had a significantly lower OS than those in the low‐hepcidin group (49.2 vs. 69.0%, respectively; P = 0.006). Multivariate analysis revealed that pretransplant serum hepcidin‐25 level, sex, and disease status were independently associated with OS. The incidence of platelet engraftment was significantly lower in the high‐hepcidin group than in the low‐hepcidin group, whereas no significant differences were observed in neutrophil and reticulocyte engraftments between these groups. Hence, pretransplant serum hepcidin levels can be a marker for predicting delayed platelet recovery after allo‐HSCT.

Potential contribution of the hepcidin-macrophage axis to plaque vulnerability in acute myocardial infarction in human

OBJECTIVES

Hepcidin-25 serves as a key peptide in the regulation of iron homeostasis and inflammation. It remains unknown whether hepcidin-25 plays an adverse role in atherosclerotic diseases. The aim of this study was to investigate whether hepcidin-25 is involved in the pathophysiology of coronary plaque vulnerability.

METHODS AND RESULTS

Serum hepcidin-25 levels were quantitatively determined by the LC-MS/MS assay system. Peripheral blood was collected from patients with acute myocardial infarction (MI, n=33) and patients with stable angina pectoris (sCAD, n=19). The levels of hepcidin-25, IL-6, and CRP were significantly higher in the patients with acute MI than in the patients with sCAD. Coronary blood was aspirated from the culprit arteries via a thrombectomy catheter in 16 of the MI patients. Serum from the aspirates contained higher levels of hepcidin-25 and IL-6 compared with the peripheral blood. In immunohistochemical staining, the macrophages of the plaques in the solid component of the aspirates were immunoreactive for hepcidin-25. To confirm the clinical observation, an in vitro study was performed using human macrophages and coronary endothelial cells. The hepcidin gene and protein were detected in the cultured macrophages but not in the endothelial cells. Hepcidin-25 exposure induced ferroportin degradation and reduced the survival rate of endothelial cells.

CONCLUSIONS

The results of the present study demonstrated that circulating hepcidin-25 and IL-6 were both elevated in the acute phase of MI and that hepcidin-25 released from plaque macrophages and other cell sources contributed to the plaque instability by inducing endothelial cell death.

Effect of Collagen Tripeptide on Atherosclerosis in Healthy Humans

AIM

Collagen tripeptide (CTP) is a functional food with a high content of Gly-X-Y tripeptides derived from collagen. The objective of this study was to evaluate the effect of CTP administration on the development of atherosclerosis in healthy individuals.

METHODS

The present study was conducted in the form of an open-label, single-dose trial for 6 months. All subjects ingested CTP twice daily: at breakfast and supper (total intake per day: 16 g). The effect of CTP on atherosclerosis was verified by measuring several indices, including serum lipid levels, toxic advanced glycation end-products (TAGE), and the cardio-ankle vascular index (CAVI), at baseline and 6 months.

RESULTS

The low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol (HDL-C) ratio (LDL-C/HDL-C ratio) was significantly reduced in patients with an initial ratio of ≥2.5 (p=0.025). A significant reduction in TAGE was observed in all the subjects (p=0.031) and in the high-risk group (p=0.024). A significant reduction in CAVI was observed in all the subjects (right side: p=0.048, left side: p=0.047). As a result of multiple regression analysis, a significant relationship between the change in CAVI and that in each factor was not observed. No adverse events were observed during the study period.

CONCLUSIONS

The results of the present study indicate that CTP contributes to the prevention and treatment of atherosclerosis in healthy humans (UMIN000018525).

Toward Worldwide Hepcidin Assay Harmonization: Identification of a Commutable Secondary Reference Material

BACKGROUND

Absolute plasma hepcidin concentrations measured by various procedures differ substantially, complicating interpretation of results and rendering reference intervals method dependent. We investigated the degree of equivalence achievable by harmonization and the identification of a commutable secondary reference material to accomplish this goal.

METHODS

We applied technical procedures to achieve harmonization developed by the Consortium for Harmonization of Clinical Laboratory Results. Eleven plasma hepcidin measurement procedures (5 mass spectrometry based and 6 immunochemical based) quantified native individual plasma samples (n = 32) and native plasma pools (n = 8) to assess analytical performance and current and achievable equivalence. In addition, 8 types of candidate reference materials (3 concentrations each, n = 24) were assessed for their suitability, most notably in terms of commutability, to serve as secondary reference material.

RESULTS

Absolute hepcidin values and reproducibility (intrameasurement procedure CVs 2.9%–8.7%) differed substantially between measurement procedures, but all were linear and correlated well. The current equivalence (intermeasurement procedure CV 28.6%) between the methods was mainly attributable to differences in calibration and could thus be improved by harmonization with a common calibrator. Linear regression analysis and standardized residuals showed that a candidate reference material consisting of native lyophilized plasma with cryolyoprotectant was commutable for all measurement procedures. Mathematically simulated harmonization with this calibrator resulted in a maximum achievable equivalence of 7.7%.

CONCLUSIONS

The secondary reference material identified in this study has the potential to substantially improve equivalence between hepcidin measurement procedures and contributes to the establishment of a traceability chain that will ultimately allow standardization of hepcidin measurement results.