Vaginal estrogen therapy is associated with increased Lactobacillus in the urine of postmenopausal women with overactive bladder symptoms.

BACKGROUND: Previous work has shown that the vaginal microbiome decreases in Lactobacillus predominance and becomes more diverse after menopause. It has also been shown that estrogen therapy restores Lactobacillus dominance in the vagina and that topical estrogen is associated with overactive bladder symptom improvement. We now know that the bladder contains a unique microbiome and that increased bladder microbiome diversity is associated with overactive bladder. However, there is no understanding of how quickly each pelvic floor microbiome responds to estrogen or if those changes are associated with symptom improvement. OBJECTIVE: This study aimed to determine if estrogen treatment of postmenopausal women with overactive bladder decreases urobiome diversity. STUDY DESIGN: We analyzed data from postmenopausal participants in 2 trials (NCT02524769 and NCT02835846) who chose vaginal estrogen as the primary overactive bladder treatment and used 0.5 g of conjugated estrogen (Premarin cream; Pfizer, New York City, NY) twice weekly for 12 weeks. Baseline and 12-week follow-up data included the Overactive Bladder questionnaire, and participants provided urine samples via catheter, vaginal swabs, perineal swabs, and voided urine samples. Microbes were detected by an enhanced culture protocol. Linear mixed models were used to estimate microbiome changes over time. Urinary antimicrobial peptide activity was assessed by a bacterial growth inhibition assay and correlated with relative abundance of members of the urobiome. RESULTS: In this study, 12 weeks of estrogen treatment resulted in decreased microbial diversity within the vagina (Shannon, P=.047; Richness, P=.043) but not in the other niches. A significant increase in Lactobacillus was detected in the bladder (P=.037) but not in the vagina (P=.33), perineum (P=.56), or voided urine (P=.28). The change in Lactobacillus levels in the bladder was associated with modest changes in urgency incontinence symptoms (P=.02). The relative abundance of the genus Corynebacterium correlated positively with urinary antimicrobial peptide activity after estrogen treatment. CONCLUSION: Estrogen therapy may change the microbiome of different pelvic floor niches. The vagina begins to decrease in diversity, and the bladder experiences a significant increase in Lactobacillus levels; the latter is correlated with a modest improvement in the symptom severity subscale of the Overactive Bladder questionnaire.

Cutaneous Burn Injury Modulates Urinary Antimicrobial Peptide Responses and the Urinary Microbiome.

OBJECTIVES: Characterization of urinary bacterial microbiome and antimicrobial peptides after burn injury to identify potential mechanisms leading to urinary tract infections and associated morbidities in burn patients. DESIGN: Retrospective cohort study using human urine from control and burn subjects. SETTING: University research laboratory. PATIENTS: Burn patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Urine samples from catheterized burn patients were collected hourly for up to 40 hours. Control urine was collected from "healthy" volunteers. The urinary bacterial microbiome and antimicrobial peptide levels and activity were compared with patient outcomes. We observed a significant increase in urinary microbial diversity in burn patients versus controls, which positively correlated with a larger percent burn and with the development of urinary tract infection and sepsis postadmission, regardless of age or gender. Urinary psoriasin and ß-defensin antimicrobial peptide levels were significantly reduced in burn patients at 1 and 40 hours postadmission. We observed a shift in antimicrobial peptide hydrophobicity and activity between control and burn patients when urinary fractions were tested against Escherichia coli and Enterococcus faecalis urinary tract infection isolates. Furthermore, the antimicrobial peptide activity in burn patients was more effective against E. coli than E. faecalis. Urinary tract infection-positive burn patients with altered urinary antimicrobial peptide activity developed either an E. faecalis or Pseudomonas aeruginosa urinary tract infection, suggesting a role for urinary antimicrobial peptides in susceptibility to select uropathogens. CONCLUSIONS: Our data reveal potential links for urinary tract infection development and several morbidities in burn patients through alterations in the urinary microbiome and antimicrobial peptides. Overall, this study supports the concept that early assessment of urinary antimicrobial peptide responses and the bacterial microbiome may be used to predict susceptibility to urinary tract infections and sepsis in burn patients.

Diagnostic accuracy of urine heparin binding protein for pediatric acute pyelonephritis.

UNLABELLED: Timely antibiotic initiation for acute pyelonephritis (APN) can prevent renal complications. We investigated whether urine heparin binding protein (UHBP), a cytokine released from activated neutrophils, was a useful diagnostic tool for APN. Febrile children with presumed APN were prospectively enrolled between January and September 2013, and divided into two groups based on urine cultures. UHBP levels were measured at enrollment in all children and 1 month after antibiotic treatment in children with APN. UHBP levels in children with APN at baseline and 1 month versus controls were 47.0 ± 8.4 and 16.6 ± 3.8 vs. 15.0 ± 2.9 ng/mL, respectively (p < 0.001). Test performance characteristics were calculated against a gold standard of positive urine cultures and compared with leukocyte esterase (LE) and nitrite measured by dipsticks and pyuria by microscopy. The sensitivity and specificity for UHBP levels ≥34 ng/mL were 100 and 100 %. Spearman's rank coefficient was used to assess the associations between routine laboratory tests and UHBP levels. Significant positive correlations were found with pyuria grade (Spearman's rho = 0.62; p < 0.001), neutrophil count (rho = 0.38; p = 0.03), and platelet count (rho = 0.39; p = 0.03). CONCLUSIONS: UHBP is a valid adjunctive diagnostic tool for aiding clinicians in making rapid treatment decisions for APN.

Role of urinary cathelicidin LL-37 and human ß-defensin 1 in uncomplicated Escherichia coli urinary tract infections.

Cathelicidin (LL-37) and human ß-defensin 1 (hBD-1) are important components of the innate defense in the urinary tract. The aim of this study was to characterize whether these peptides are important for developing uncomplicated Escherichia coli urinary tract infections (UTIs). This was investigated by comparing urinary peptide levels of UTI patients during and after infection to those of controls, as well as characterizing the fecal flora of participants with respect to susceptibility to LL-37 and in vivo virulence. Forty-seven UTI patients and 50 controls who had never had a UTI were included. Participants were otherwise healthy, premenopausal, adult women. LL-37 MIC levels were compared for fecal E. coli clones from patients and controls and were also compared based on phylotypes (A, B1, B2, and D). In vivo virulence was investigated in the murine UTI model by use of selected fecal isolates from patients and controls. On average, UTI patients had significantly more LL-37 in urine during infection than postinfection, and patient LL-37 levels postinfection were significantly lower than those of controls. hBD-1 showed similar urine levels for UTI patients and controls. Fecal E. coli isolates from controls had higher LL-37 susceptibility than fecal and UTI E. coli isolates from UTI patients. In vivo studies showed a high level of virulence of fecal E. coli isolates from both patients and controls and showed no difference in virulence correlated with the LL-37 MIC level. The results indicate that the concentration of LL-37 in the urinary tract and low susceptibility to LL-37 may increase the likelihood of UTI in a complex interplay between host and pathogen attributes.

Effects of subcutaneous and intravenous golimumab on inflammatory biomarkers in patients with rheumatoid arthritis: results of a phase 1, randomized, open-label trial.

OBJECTIVE: To evaluate the effects of the anti-TNF-α monoclonal antibody golimumab, administered by s.c. injection or i.v. infusion, on markers of inflammation in patients with RA. METHODS: In this phase 1, open-label study, patients with active RA were randomized to receive s.c. golimumab 100 mg at baseline and every 4 weeks through week 20 (n = 33; group 1) or i.v. golimumab 2 mg/kg at baseline and week 12 (n = 16; group 2). Serum levels of CRP, IL-6, serum amyloid A (SAA), TNF receptor II (TNFRII), MMP-3, hyaluronic acid, haptoglobin, ferritin and haemoglobin and serum/urine hepcidin were measured at various time points. Associations between the biomarkers were assessed with Spearman's correlations. RESULTS: In both groups 1 and 2, decreases in mean serum levels of CRP, IL-6, SAA, TNFRII, MMP-3, haptoglobin, ferritin and hepcidin, and mean urine levels of hepcidin occurred within 1 week and were sustained through week 8. Decreases in concentrations of serum CRP, IL-6, SAA, MMP-3, hepcidin, ferritin and haptoglobin and urine hepcidin were maintained through week 24 in group 1, but began to reverse after week 8 in group 2. Among all patients, decreases in serum hepcidin correlated significantly with decreases in serum CRP and ferritin. CONCLUSION: Decreases in serum and urine concentrations of markers of inflammation occurred as early as 24 h after treatment with golimumab, and most of these improvements were sustained through week 24 in group 1.

The antimicrobial peptide cathelicidin protects the urinary tract against invasive bacterial infection.

The urinary tract functions in close proximity to the outside environment, yet must remain free of microbial colonization to avoid disease. The mechanisms for establishing an antimicrobial barrier in this area are not completely understood. Here, we describe the production and function of the cathelicidin antimicrobial peptides LL-37, its precursor hCAP-18 and its ortholog CRAMP in epithelial cells of human and mouse urinary tract, respectively. Bacterial contact with epithelial cells resulted in rapid production and secretion of the respective peptides, and in humans LL-37/hCAP-18 was released into urine. Epithelium-derived cathelicidin substantially contributed to the protection of the urinary tract against infection, as shown using CRAMP-deficient and neutrophil-depleted mice. In addition, clinical E. coli strains that were more resistant to LL-37 caused more severe urinary tract infections than did susceptible strains. Thus, cathelicidin seems to be a key factor in mucosal immunity of the urinary tract.

A composite urine biomarker reflects interstitial inflammation in lupus nephritis kidney biopsies.

The initial treatment of lupus nephritis is usually based on a renal biopsy. Subsequent disease flares, however, are often treated without the benefit of kidney pathology because repeat biopsies are infrequent. A noninvasive, real-time method to assess renal pathology would be useful to adjust treatment and improve outcome. To develop such a method we collected urine samples at or close to the time of 64 biopsies from 61 patients with lupus nephritis to identify potential biomarkers of tubulointerstitial inflammation and correlated these to biopsy parameters scored by a renal pathologist using a semiquantitative scale. Linear discriminant analysis was used to weight variables and derive composite biomarkers that identified the level of tubulointerstitial inflammation based on urine concentrations of monocyte chemotactic protein-1, hepcidin (a marker of active lupus), and liver fatty acid-binding protein. The discriminant function that described the most accurate composite biomarkers included urine monocyte chemotactic protein-1 and serum creatinine as the independent variables. This composite had sensitivity, specificity, positive predictive value, and negative predictive value of 100, 81, 67, and 100%, respectively. Only 14% of the biopsies were misclassified. Thus, specific renal pathologic lesions can be modeled by composite biomarkers to noninvasively follow and adjust the treatment of lupus nephritis reflecting renal injury.

Identification of a novel mutation in the HAMP gene that causes non-detectable hepcidin molecules in a Japanese male patient with juvenile hemochromatosis.

Hepcidin is an iron-regulatory hepatic peptide hormone encoded by the HAMP gene that downregulates iron export from enterocytes and macrophages into the blood plasma. In this study, we identified a novel mutation in the HAMP gene of a 58-year-old Japanese male patient with hemochromatosis. By direct sequencing of the five hereditary hemochromatosis-related genes, HFE, HAMP, HJV, TFR2, and SLC40A1, the previously unreported p.R75X mutation was identified, and the patient was found to be homozygous for the mutation. No other potentially pathogenic mutations were detected. In an LC-MS/MS analysis, hepcidin molecules were not detected in the patient's serum or urine. These results indicate that the p.R75X mutation causes iron overload by impairing the hepcidin system.

Hepcidin concentrations in serum and urine correlate with iron homeostasis in preterm infants.

OBJECTIVES: To evaluate whether hepcidin concentrations in serum (Hep((S))) and urine (Hep((U))) correlate with iron metabolism, erythropoiesis, and inflammation in preterm infants. STUDY DESIGN: Thirty-one preterm infants (23-32 weeks gestational age) were included. The concentration of the mature, 25 amino-acid form of hepcidin was determined by enzyme-linked immunosorbent assay in serum, urine, blood counts, reticulocytes, and iron measurements. RESULTS: Median (IQR) Hep((S)) was 52.4 (27.9-91.9) ng/mL. The highest values were measured in patients with systemic inflammation. Hep((S)) and Hep((U)) correlated strongly (P = .0007). Hep((S)) and Hep((U)) also correlated positively with ferritin (P = .005 and P = .0002) and with reticulocyte hemoglobin content (P = .015 and P = .015). Hep((S)) and Hep((U)) correlated negatively with soluble transferrin receptor/ferritin-ratio (P = .005 and P = .003). Infants with lower hemoglobin concentrations and higher reticulocyte counts had lower Hep((S)) (P = .0016 and P = .0089). CONCLUSION: In sick preterm infants, iron status, erythropoiesis, anemia, and inflammation correlated with the mature 25 amino-acid form of hepcidin. Further evaluation of Hep((U)) for non-invasive monitoring of iron status in preterm infants appears justified.

Proinflammatory state, hepcidin, and anemia in older persons.

In patients with overt inflammatory diseases, up-regulated hepcidin impairs iron absorption and macrophage release, causing anemia. Whether the mild proinflammatory state of aging is associated with increased hepcidin is unknown. We characterized the relationships between urinary hepcidin, iron status, anemia, and inflammation in 582 patients 65 years or older participating in the InCHIANTI (Invecchiare in Chianti, "Aging in the Chianti Area") study, a population-based study of aging in Tuscany, Italy. Compared with nonanemic persons, urinary hepcidin (nanograms/milligram of urinary creatinine) was significantly lower in iron deficiency and inflammation anemia compared with no anemia or other anemia types. Urinary hepcidin was positively correlated with log(ferritin) and negatively correlated with the soluble transferrin receptor/log(ferritin) ratio but not correlated with markers of inflammation: interleukin-6 (IL-6), IL-1beta, tumor necrosis factor-alpha, and C-reactive protein (CRP). Lower iron was significantly correlated with higher IL-6 and CRP. Adjusting for confounders, IL-6 and CRP remained significantly associated with serum iron, with no evidence that such a relationship was accounted for by variability in urinary hepcidin. In conclusion, elevated proinflammatory markers were associated with anemia and low iron status, but not with higher urinary hepcidin. Future studies should test whether hepcidin production becomes up-regulated only in situations of overt inflammation.

Greater increase in urinary hepcidin predicts protection from acute kidney injury after cardiopulmonary bypass.

BACKGROUND: Acute kidney injury (AKI) is a common and serious complication of cardiopulmonary bypass (CPB) surgery. Hepcidin, a peptide hormone that regulates iron homeostasis, is a potential biomarker of AKI following CPB. METHODS: We investigated the association between post-operative changes in serum and urinary hepcidin and AKI in 93 patients undergoing CPB. RESULTS: Twenty-five patients developed AKI based on the Risk, Injury, Failure, Loss, End-stage kidney disease (RIFLE) criteria in the first 5 days. Serum hepcidin, urine hepcidin concentration, the urinary hepcidin:creatinine ratio and fractional excretion of hepcidin in urine rose significantly after surgery. However, urine hepcidin concentration and urinary hepcidin:creatinine ratio were significantly lower at 24 h in patients with RIFLE-Risk, Injury or Failure compared to those without AKI (P = 0.0009 and P < 0.0001, respectively). Receiver operator characteristic analysis showed that lower 24-h urine hepcidin concentration and urinary hepcidin:creatinine ratio were sensitive and specific predictors of AKI. The urinary hepcidin:creatinine ratio had an area under the curve for the diagnosis of RIFLE ≥ risk at 24 h of 0.77 and of 0.84 for RIFLE ≥ injury. Urinary hepcidin had similar predictive accuracy. Such predictive ability remained when patients with early creatinine increases were excluded. CONCLUSIONS: Urinary hepcidin and hepcidin:creatinine ratio are biomarkers of AKI after CPB, with an inverse association between its increase at 24 h and risk of AKI in the first five post-operative days. Measuring hepcidin in the urine on the first day following surgery may deliver earlier diagnosis and interventions.

Hepcidin and hemoglobin content parameters in the diagnosis of iron deficiency in rheumatoid arthritis patients with anemia.

OBJECTIVE: To explore the utility of the novel iron indices hepcidin, reticulocyte hemoglobin content (Ret-Hgb), and erythrocyte (red blood cell) hemoglobin content (RBC-Hgb) for detection of iron deficiency in rheumatoid arthritis (RA) patients with anemia and active inflammation and to compare these indices with conventional parameters of iron deficiency. METHODS: Blood samples from 106 outpatients with RA were analyzed in a cross-sectional exploratory study. Forty patients were classified as having either iron deficiency anemia (IDA), anemia of chronic disease (ACD), their combination (IDA/ACD), or "other anemia" based on biochemical parameters for inflammation and iron deficiency. The ability of serum and urine hepcidin, Ret-Hgb, and RBC-Hgb measurement to discriminate among these states was evaluated. RESULTS: Hepcidin content in serum from patients in the IDA group as well as that from patients in the combined IDA/ACD group differed significantly from that in serum from patients in the ACD group. This difference was also observed with hepcidin in urine, Ret-Hgb, and RBC-Hgb, although with less significance. The area under the receiver operating characteristic curve for serum hepcidin was 0.88 for the comparison of IDA/ACD patients with ACD patients and 0.92 for the comparison of the combined IDA group and IDA/ACD group to all other patients with anemia. Hepcidin at <2.4 nmoles/liter had a sensitivity of 89% and a specificity of 88% to distinguish IDA/ACD from ACD. Both Ret-Hgb and RBC-Hgb measurements also allowed differentiation between these latter groups, with a sensitivity of 67% and 89%, respectively, and a specificity of 100% and 75%, respectively. CONCLUSION: Serum hepcidin and, to a lesser extent, urine hepcidin, Ret-Hgb, and RBC-Hgb, are potential useful indicators for detecting iron deficiency in RA patients with anemia and active inflammation.

Elevated urine levels of heparin-binding protein in children with urinary tract infection.

BACKGROUND: Urinary tract infection (UTI) is a common infection diagnosis in children, and efficient diagnosis and treatment are important to avoid serious complications. In this study we investigated whether urinary levels of neutrophil-derived heparin-binding protein (HBP) can be used as a marker of UTI in children. These results were compared to those of dipstick analysis, interleukin-6 (IL-6) analysis in urine, and bacterial culturing. METHODS: Seventy-eight children aged 0-18 years with fever and/or symptoms indicating UTI were enrolled in a prospective consecutive study. Urine samples were cultured and analyzed with dipstick, and concentrations of HBP and IL-6 were measured. RESULTS: Fifteen patients were classified as having UTI, 30 patients had fever but were diagnosed with a non-urinary tract infection, and 33 patients had neither UTI nor fever. Using a urine HBP (U-HBP) cut-off level of 32 ng/mL, the sensitivity and specificity for detecting UTI were 93.3 and 90.3 %, respectively. Receiver operating characteristic curves demonstrated that U-HBP levels were a higher specificity indicator of UTI than urine white blood cell counts or urine IL-6 levels; they also showed a higher sensitivity than the results of the urine nitrite test. All patients with significant growth of clinically relevant bacteria had elevated U-HBP levels. CONCLUSION: The results indicate that rapid analysis of U-HBP can provide helpful guidance in the management of children with suspected UTI.

Increased hepcidin expression in multibacillary leprosy.

Iron is essential for all organisms and its availability can control the growth of microorganisms; therefore, we examined the role of iron metabolism in multibacillary (MB) leprosy, focusing on the involvement of hepcidin. Erythrograms, iron metabolism parameters, pro-inflammatory cytokines and urinary hepcidin levels were evaluated in patients with MB and matched control subjects. Hepcidin expression in MB lesions was evaluated by quantitative polymerase chain reaction. The expression of ferroportin and hepcidin was evaluated by immunofluorescence in paucibacillary and MB lesions. Analysis of hepcidin protein levels in urine and of hepcidin mRNA and protein levels in leprosy lesions and skin biopsies from healthy control subjects showed elevated hepcidin levels in MB patients. Decreases in haematologic parameters and total iron binding capacity were observed in patients with MB leprosy. Moreover, interleukin-1 beta, ferritin, soluble transferrin receptor and soluble transferrin receptor/log ferritin index values were increased in leprosy patients. Hepcidin was elevated in lepromatous lesions, whereas ferroportin was more abundant in tuberculoid lesions. In addition, hepcidin and ferroportin were not colocalised in the biopsies from leprosy lesions. Anaemia was not commonly observed in patients with MB; however, the observed changes in haematologic parameters indicating altered iron metabolism appeared to result from a mixture of anaemia of inflammation and iron deficiency. Thus, iron sequestration inside host cells might play a role in leprosy by providing an optimal environment for the bacillus.

Dysmetabolic hyperferritinemia is associated with normal transferrin saturation, mild hepatic iron overload, and elevated hepcidin.

Hyperferritinemia is common in individuals with the metabolic syndrome (dysmetabolic hyperferritinemia), but its pathophysiology and the degree to which it reflects tissue iron overload remains unclear. We conducted a cross-sectional study evaluating ten cases with dysmetabolic hyperferritinemia for liver iron overload and compared their serum iron indices and urine hepcidin levels to healthy controls. Seven out of ten cases had mild hepatic iron overload by magnetic resonance imaging (MRI) (median, 75 micromol/g dry weight). Cases had higher serum ferritin than controls (median, 672 microg/L vs. 105 microg/L, p < 0.001), but the median transferrin saturation was not significantly different (38% vs. 36%, p = 0.5). Urinary hepcidin was elevated in dysmetabolic hyperferritinemia (median; 1,584 g/mg of creatinine vs. 799 ng/mg of creatinine, p = 0.05). Dysmetabolic hyperferritinemia is characterized by hyperferritinemia with normal transferrin saturation, elevated hepcidin levels, and mild liver iron overload in a subset of patients.

Hepcidin response to acute iron intake and chronic iron loading in dysmetabolic iron overload syndrome.

BACKGROUND: The pathogenesis of dysmetabolic iron overload syndrome (DIOS) is still unclear. Hepcidin is the key regulator of iron homeostasis controlling iron absorption and macrophage release. AIM: To investigate hepcidin regulation by iron in DIOS. METHODS: We analysed urinary hepcidin at baseline and 24 h after a 65 mg oral iron dose in 24 patients at diagnosis and after iron depletion (n = 13) and compared data with those previously observed in 23 healthy controls. Serum iron indices, liver histology and metabolic data were available for all patients. RESULTS: At diagnosis, hepcidin values were significantly higher than in controls (P < 0.001). After iron depletion, hepcidin levels decreased to normal values in all patients. At baseline, a significant response of hepcidin to iron challenge was observed only in the subgroup with lower basal hepcidin concentration (P = 0.007). In iron-depleted patients, urinary hepcidin significantly increased after oral iron test (P = 0 .006). CONCLUSIONS: Ours findings suggest that in DIOS, the progression of iron accumulation is counteracted by the increase in hepcidin production and progressive reduction of iron absorption, explaining why these patients develop a mild-moderate iron overload that tends to a plateau.

Urine hepcidin has additive value in ruling out cardiopulmonary bypass-associated acute kidney injury: an observational cohort study.

INTRODUCTION: Conventional markers of acute kidney injury (AKI) lack diagnostic accuracy and are expressed only late after cardiac surgery with cardiopulmonary bypass (CPB). Recently, interest has focused on hepcidin, a regulator of iron homeostasis, as a unique renal biomarker. METHODS: We studied 100 adult patients in the control arm of a randomized, controlled trial http://www.clinicaltrials.gov/NCT00672334 who were identified as being at increased risk of AKI after cardiac surgery with CPB. AKI was defined according to the Risk, Injury, Failure, Loss, End-stage renal disease classification of AKI classification stage. Samples of plasma and urine were obtained simultaneously (1) before CPB (2) six hours after the start of CPB and (3) twenty-four hours after CPB. Plasma and urine hepcidin 25-isoforms were quantified by competitive enzyme-linked immunoassay. RESULTS: In AKI-free patients (N = 91), urine hepcidin concentrations had largely increased at six and twenty-four hours after CPB, and they were three to seven times higher compared to patients with subsequent AKI (N = 9) in whom postoperative urine hepcidin remained at preoperative levels (P = 0.004, P = 0.002). Furthermore, higher urine hepcidin and, even more so, urine hepcidin adjusted to urine creatinine at six hours after CPB discriminated patients who did not develop AKI (area under the curve (AUC) receiver operating characteristic curve 0.80 [95% confidence interval (95% CI) 0.71 to 0.87] and 0.88 [95% CI 0.78 to 0.97]) or did not need renal replacement therapy initiation (AUC 0.81 [95% CI 0.72 to 0.88] 0.88 [95% CI 0.70 to 0.99]) from those who did. At six hours, urine hepcidin adjusted to urine creatinine was an independent predictor of ruling out AKI (P = 0.011). Plasma hepcidin did not predict no development of AKI. The study findings remained essentially unchanged after excluding patients with preoperative chronic kidney disease. CONCLUSIONS: Our findings suggest that urine hepcidin is an early predictive biomarker of ruling out AKI after CPB, thereby contributing to early patient risk stratification.

Urinary hepcidin identifies a serum ferritin cut-off for iron supplementation in young athletes: a pilot study.

The use of iron supplements should be a judicious choice, primarily when considering the possible risks deriving from an unjustified treatment. In trained athletes, levels of ferritin between 15 and 30 microg/L are frequently observed. Within this ferritin range, the usefulness of iron supplementation is still controversial. The aim of the present study is to evaluate the clinical usefulness of hepcidin assessment in the analysis of the iron status of young non-anemic athletes. Fifty young athletes were enrolled. The subjects were divided into 4 groups according to their ferritin levels. No statistically significant difference was found regarding hepcidin levels between athletes with ferritin lower than 15 microg/L and those in the 15-30 microg/L range. Similarly, no difference was found between athletes with ferritin higher than 50 microg/L and those in the 30-50 microg/L range. On the contrary, statistically significant differences were found between athletes with ferritin levels ranging from 15 to 30 microg/L and those in the 30-50 microg/L range. The present study suggests that serum ferritin levels below 30 microg/L indicate an asymptomatic iron deficiency status inhibiting hepcidin expression and that 30 microg/L should be considered the ferritin cut-off when considering an iron supplementation in young athletes.

Reproducibility of and correspondence among different hepcidin forms in blood and urine and their relationships to iron status in healthy, male Guatemalan volunteers observed over 9 weeks.

BACKGROUND/AIMS: Prohepcidin and the active form hepcidin-25 are two variants of the peptide hormone hepcidin for iron homoeostasis. Their regulatory role and usefulness as biomarkers of the iron status are uncertain. Our aim is to describe the intra-individual variance of serum and urinary hepcidin-25 and prohepcidin concentrations, the mutual associations of the 4 hepcidin formats, and their correspondence with iron status variables in male Guatemalan volunteers. METHODS: Eight healthy adult males provided serial samples of serum and urine without previous iron dosing over 6 intervals during a 9-week protocol period. Prohepcidin was assayed by a commercial enzyme immunoassay, and hepcidin-25 species in serum and urine were analysed by time-of-flight mass spectrometry after prior enrichment procedures. RESULTS: Serum hepcidin-25 levels correlated significantly with urinary hepcidin-25 concentrations, whereas serum and urinary prohepcidin were not associated with one another or with the homologous or converse formats for hepcidin-25. Serum ferritin and transferrin saturation were significantly correlated with serum hepcidin-25 concentrations, but not with urine hepcidin-25 or with either format of prohepcidin. CONCLUSION: Hepcidin-25 shows correspondence across biological fluids, and the background 'status' of hepcidin activation may be related to the host's iron stores, whereas prohepcidin concentrations showed no promise in this regard.

A novel TMPRSS6 mutation that prevents protease auto-activation causes IRIDA.

IRIDA (iron-refractory iron-deficiency anaemia) is a rare autosomal-recessive disorder hallmarked by hypochromic microcytic anaemia, low transferrin saturation and high levels of the iron-regulated hormone hepcidin. The disease is caused by mutations in the transmembrane serine protease TMPRSS6 (transmembrane protease serine 6) that prevent inactivation of HJV (haemojuvelin), an activator of hepcidin transcription. In the present paper, we describe a patient with IRIDA who carries a novel mutation (Y141C) in the SEA domain of the TMPRSS6 gene. Functional characterization of the TMPRSS6(Y141C) mutant protein in cultured cells showed that it localizes to similar subcellular compartments as wild-type TMPRSS6 and binds HJV, but fails to auto-catalytically activate itself. As a consequence, hepcidin mRNA expression is increased, causing the clinical symptoms observed in this IRIDA patient. The present study provides important mechanistic insight into how TMPRSS6 is activated.