Serum hepcidin concentrations in relation to iron status in children with type 1 diabetes

Chronic low-grade inflammation in type 1 diabetes (T1D) might increase hepcidin synthesis, possibly resulting in functional iron deficiency (FID). We hypothesized that in T1D children with FID, hepcidin concentrations are increased compared to those with normal iron status and those with absolute iron deficiency (AID). We evaluated hepcidin concentrations in T1D children in relation to iron status, and investigated whether hepcidin is useful in assessing FID. A cross-sectional study was conducted. FID was defined as elevated zinc protoporphyrin/heme ratio and/or red blood cell distribution width, and AID as low serum ferritin concentration. Post-hoc analyses with different definitions of FID were performed, using transferrin saturation and reticulocyte hemoglobin content. Serum hepcidin concentrations were measured using mass-spectrometry. The IRODIAB-study is registered at www.trialregister.nl (NTR4642). This study included 215 T1D children with a median age of 13.7 years (Q1–Q3: 10.1–16.3). The median (Q1–Q3) hepcidin concentration in patients with normal iron status was 1.8 nmol/l (0.9–3.3), in AID-patients, 0.4 nmol/l (0.4–0.4) and in FID-patients, 1.6 nmol/l (0.7–3.5). Hepcidin concentrations in FID-patients were significantly higher than in AID-patients (p < 0.001). Irrespective of FID-definition used, hepcidin concentrations did not differ between FID-patients and patients with normal iron status. This might be explained by the influence of various factors on hepcidin concentrations, and/or by differences in response of iron parameters over time. Single hepcidin measurements do not seem useful in assessing FID in T1D children. Multiple hepcidin measurements over time in future studies, however, might prove to be more useful in assessing FID in children with T1D

Influence of periodizing dietary carbohydrate on iron regulation and immune function in elite triathletes

Sleeping with low carbohydrate (CHO) availability is a dietary strategy that may enhance training adaptation. However, the impact on an athlete’s health is unclear. This study quantified the effect of a short-term “sleep-low” dietary intervention on markers of iron regulation and immune function in athletes. In a randomized, repeated-measures design, 11 elite triathletes completed two 4-day mixed cycle run training blocks. Key training sessions were structured such that a high-intensity training session was performed in the field on the afternoon of Days 1 and 3, and a low-intensity training (LIT) session was performed on the following morning in the laboratory (Days 2 and 4). The ingestion of CHO was either divided evenly across the day (HIGH) or restricted between the high-intensity training and LIT sessions, so that the LIT session was performed with low CHO availability (LOW). Venous blood and saliva samples were collected prior to and following each LIT session and analyzed for interleukin-6, hepcidin 25, and salivary immunoglobulin-A. Concentrations of interleukin-6 increased acutely after exercise (p < .001), but did not differ between dietary conditions or days. Hepcidin 25 increased 3-hr postexercise (p < .001), with the greatest increase evident after the LOW trial on Day 2 (2.5 ± 0.9 fold increase ±90% confidence limit). The salivary immunoglobulin-A secretion rate did not change in response to exercise; however, it was highest during the LOW condition on Day 4 (p = .046). There appears to be minimal impact to markers of immune function and iron regulation when acute exposure to low CHO availability is undertaken with expert nutrition and coaching input

Unraveling Hepcidin Plasma Protein Binding: Evidence from Peritoneal Equilibration Testing

Peptide hormone hepcidin regulates systemic iron metabolism and has been described to be partially bound to &alpha;2-macroglobulin and albumin in blood. However, the reported degree of hepcidin protein binding varies between &lt;3% and &asymp;89%. Since protein-binding may influence hormone function and quantification, better insight into the degree of hepcidin protein binding is essential to fully understand the biological behavior of hepcidin and interpretation of its measurement in patients. Here, we used peritoneal dialysis to assess human hepcidin protein binding in a functional human setting for the first time. We measured freely circulating solutes in blood and peritoneal fluid of 14 patients with end-stage renal disease undergoing a peritoneal equilibration test to establish a curve describing the relation between molecular weight and peritoneal clearance. Calculated binding percentages of total cortisol and testosterone confirmed our model. The protein-bound fraction of hepcidin was calculated to be 40% (&plusmn;23%). We, therefore, conclude that a substantial proportion of hepcidin is freely circulating. Although a large inter-individual variation in hepcidin clearance, besides patient-specific peritoneal transport characteristics, may have affected the accuracy of the determined binding percentage, we describe an important step towards unraveling human hepcidin plasma protein binding in vivo including the caveats that need further research

PowerPoint Slides for: Cardiac Hepcidin Expression Associates with Injury Independent of Iron

Background: Hepcidin regulates systemic iron homeostasis by downregulating the iron exporter ferroportin. Circulating hepcidin is mainly derived from the liver but hepcidin is also produced in the heart. We studied the differential and local regulation of hepcidin gene expression in response to myocardial infarction (MI) and/or chronic kidney disease (CKD). We hypothesized that cardiac hepcidin gene expression is induced by and regulated to severity of cardiac injury, either through direct (MI) or remote (CKD) stimuli, as well as through increased local iron content. Methods: Nine weeks after subtotal nephrectomy (SNX) or sham surgery (CON), rats were subjected to coronary ligation (CL) or sham surgery to realize 4 groups: CON, SNX, CL and SNX + CL. In week 16, the gene expression of hepcidin, iron and damage markers in cardiac and liver tissues was assessed by quantitative polymerase chain reaction and ferritin protein expression was studied by immunohistochemistry. Results: Cardiac hepcidin messenger RNA (mRNA) expression was increased 2-fold in CL (p = 0.03) and 3-fold in SNX (p = 0.01). Cardiac ferritin staining was not different among groups. Cardiac hepcidin mRNA expression correlated with mRNA expression levels of brain natriuretic peptide (β = 0.734, p &lt; 0.001) and connective tissue growth factor (β = 0.431, p = 0.02). In contrast, liver hepcidin expression was unaffected by SNX and CL alone, while it had decreased 50% in SNX + CL (p &lt; 0.05). Hepatic ferritin immunostaining was not different among groups. Conclusions: Our data indicate differences in hepcidin regulation in liver and heart and suggest a role for injury rather than iron as the driving force for cardiac hepcidin expression in renocardiac failure

Urinary proteomic profiling reveals diclofenac-induced renal injury and hepatic regeneration in mice

Contains fulltext : 117320.pdf (publisher's version ) (Closed access)Diclofenac (DF) is a widely used non-steroidal anti-inflammatory drug for the treatment of rheumatic disorders, but is often associated with liver injury. We applied urinary proteomic profiling using MALDI-TOF MS to identify biomarkers for DF-induced hepatotoxicity in mice. Female CH3/HeOUJIco mice were treated with 75mg/kg bw DF by oral gavage and 24h urine was collected. Proteins identified in urine of DF-treated mice included epidermal growth factor, transthyretin, kallikrein, clusterin, fatty acid binding protein 1 and urokinase, which are related to liver regeneration but also to kidney injury. Both organs showed enhanced levels of oxidative stress (TBARS, p<0.01). Kidney injury was confirmed by histology and increased Kim1 and Il-6 mRNA expression levels (p<0.001 and p<0.01). Liver histology and plasma ALT levels in DF-treated mice were not different from control, but mRNA expression of Stat3 (p<0.001) and protein expression of PCNA (p<0.05) were increased, indicating liver regeneration. In conclusion, urinary proteome analysis revealed that DF treatment in mice induced kidney and liver injury. Within 24h, however, the liver was able to recover by activating tissue regeneration processes. Hence, the proteins found in urine of DF-treated mice represent kidney damage rather than hepatic injury

PowerPoint Slides for: 3A Cardiac Hepcidin Expression Associates with Injury Independent of Iron

Background%3A Hepcidin regulates systemic iron homeostasis by downregulating the iron exporter ferroportin. Circulating hepcidin is mainly derived from the liver but hepcidin is also produced in the heart. We studied the differential and local regulation of hepcidin gene expression in response to myocardial infarction (MI) and/or chronic kidney disease (CKD). We hypothesized that cardiac hepcidin gene expression is induced by and regulated to severity of cardiac injury, either through direct (MI) or remote (CKD) stimuli, as well as through increased local iron content. Methods%3A Nine weeks after subtotal nephrectomy (SNX) or sham surgery (CON), rats were subjected to coronary ligation (CL) or sham surgery to realize 4 groups%3A CON, SNX, CL and SNX + CL. In week 16, the gene expression of hepcidin, iron and damage markers in cardiac and liver tissues was assessed by quantitative polymerase chain reaction and ferritin protein expression was studied by immunohistochemistry. Results%3A Cardiac hepcidin messenger RNA (mRNA) expression was increased 2-fold in CL (p = 0.03) and 3-fold in SNX (p = 0.01). Cardiac ferritin staining was not different among groups. Cardiac hepcidin mRNA expression correlated with mRNA expression levels of brain natriuretic peptide (β = 0.734, p &lt; 0.001) and connective tissue growth factor (β = 0.431, p = 0.02). In contrast, liver hepcidin expression was unaffected by SNX and CL alone, while it had decreased 50%25 in SNX + CL (p &lt; 0.05). Hepatic ferritin immunostaining was not different among groups. Conclusions%3A Our data indicate differences in hepcidin regulation in liver and heart and suggest a role for injury rather than iron as the driving force for cardiac hepcidin expression in renocardiac failure

Provisional standardization of hepcidin assays:Creating a traceability chain with a primary reference material, candidate reference method and a commutable secondary reference material

Background Hepcidin concentrations measured by various methods differ considerably, complicating interpretation. Here, a previously identified plasma-based candidate secondary reference material (csRM) was modified into a serum-based two-leveled sRM. We validated its functionality to increase the equivalence between methods for international standardization. Methods We applied technical procedures developed by the International Consortium for Harmonization of Clinical Laboratory Results. The sRM, consisting of lyophilized serum with cryolyoprotectant, appeared commutable among nine different measurement procedures using 16 native human serum samples in a first round robin (RR1). Harmonization potential of the sRM was simulated in RR1 and evaluated in practice in RR2 among 11 measurement procedures using three native human plasma samples. Comprehensive purity analysis of a candidate primary RM (cpRM) was performed by state of the art procedures. The sRM was value assigned with an isotope dilution mass spectrometry-based candidate reference method calibrated using the certified pRM. Results The inter-assay CV without harmonization was 42.1% and 52.8% in RR1 and RR2, respectively. In RR1, simulation of harmonization with sRM resulted in an inter-assay CV of 11.0%, whereas in RR2 calibration with the material resulted in an inter-assay CV of 19.1%. Both the sRM and pRM passed international homogeneity criteria and showed long-term stability. We assigned values to the low (0.95\ub10.11 nmol/L) and middle concentration (3.75\ub10.17 nmol/L) calibrators of the sRM. Conclusions Standardization of hepcidin is possible with our sRM, which value is assigned by a pRM. We propose the implementation of this material as an international calibrator for hepcidin