Integrated proteomic and metabolomic profiling of urine of renal anemia patients uncovers the molecular mechanisms of roxadustat.

Roxadustat (FG-4592) is a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) prescribed to patients with low hemoglobin associated with chronic kidney disease. Due to the various HIF-mediated adaptive responses, FG-4592 has attracted significant interest for therapeutic use against various diseases. However, the clinical application of Roxadustat remains limited due to a lack of understanding of its underlying mechanisms. Herein, we performed label-free quantitative liquid chromatography with tandem mass spectrometry (LC-MS-MS) proteomics and un-targeted metabolomics to study the protein and metabolite alterations in the urine of renal anemia patients before and after Roxadustat therapy. The results were validated by parallel reaction monitoring (PRM). A total of 46 proteins (including 15 upregulated and 31 downregulated proteins) and 207 metabolites were significantly altered after Roxadustat treatment in urine samples obtained from renal anemia patients. Then, the altered proteins were further validated by PRM. Finally, proteomics combined with metabolomics analysis revealed that the Ras signalling pathway, cysteine and methionine metabolism, arginine and proline metabolism, and cholesterol metabolism were the main pathways altered by Roxadustat treatment. The multi-omics analysis revealed that Roxadustat could alter the protein expression and reverse the potential metabolic changes to exert hypotensive, lipid metabolic regulation, and renoprotective effects in clinical practice.

Changes in urinary kidney injury molecule-1 levels after blood transfusions in preterm infants.

Literature supports an association between transfusions and gut injury in preterm infants. We hypothesized that packed red blood (PRBC) transfusions are associated with kidney inflammation marked by a rise in urinary levels of Kidney Injury Molecule 1 (KIM-1). Prospectively, KIM-1 levels were measured before and then at 6, 12 and 24 h after a PRBC transfusion. Results are presented as mean (± SD) and median (IQR). Thirty-four infants, birth weight 865 (± 375) g, had higher pretransfusion KIM-1 levels of 2270 (830, 3250) pg/mg than what is normal for age. These were not associated with hematocrit levels. KIM-1 levels peaked between 6 and 12 h after the transfusion. Levels peaked to 3300 (1990, 6830) pg/mg; levels returned to pretransfusion levels of 2240 (1240, 3870) pg/mg by 24 h, p < 0.01. The 24-h post-transfusion KIM-1 levels were similar to pretransfusion levels, p = 0.63. PRBC transfusions in preterm infants are associated with an elevation in urinary KIM-1 levels. The mechanism of this association may be important in studying transfusion associated organ injury. KIM-1, as an inflammatory marker, may be helpful in assessing the effect of different transfusion volumes or in evaluating operational thresholds of anemia in premature infants.

Delayed haemolysis following artesunate in a child with profound anaemia and Coca-Cola-coloured urine.

An 8-year-old girl of African descent presented to the hospital with a headache, lethargy, pallor and 'Coca-Cola'-coloured urine. She had been admitted 11 days before with Plasmodium falciparum malaria, which was successfully treated with 48 hours of parenteral artesunate. Investigations revealed signs of severe haemolytic anaemia, with a haemoglobin level of 52 g/L that reached a nadir of 10 g/L within 4 hours, in addition to haemoglobinuria, hyperbilirubinaemia and raised lactate dehydrogenase levels. She was diagnosed with post-artemisinin delayed haemolysis, which is usually self-limiting but has the potential to cause severe, life-threatening anaemia 7-21 days following malaria treatment with artesunate. There was excellent response to blood transfusion, and the child made a full recovery. This case highlights the importance of providing safety netting advice regarding signs and symptoms of anaemia to patients receiving artesunate, in addition to monitoring of haemoglobin levels in the weeks after treatment.

Erythropoietin production by the kidney and the liver in response to severe hypoxia evaluated by Western blotting with deglycosylation.

The detection of erythropoietin (Epo) protein by Western blotting has required pre-purification of the sample. We developed a new Western blot method to detect plasma and urinary Epo using deglycosylation. Epo in urine and tissue, and erythropoiesis-stimulating agents (ESAs) in urine were directly detected by our Western blotting. Plasma Epo and ESAs were not detected by direct application but were detected by our Western blotting after deglycosylation. The broad bands of Epo and ESAs were shifted to 22 kDa by deglycosylation except for PEG-bound epoetin ß pegol. The 22 kDa band from an anemic patient's urine was confirmed by Liquid Chromatography/Mass Spectrometry (LC/MS) to contain human Epo. Severe hypoxia (7% O2, 4 hr) caused a 400-fold increase in deglycosylated Epo expression in rat kidneys, which is consistent with the increases in both Epo gene expression and plasma Epo concentration. Immunohistochemistry showed Epo expression in nephrons but not in interstitial cells under control conditions, and hypoxia increased Epo expression in interstitial cells but not in tubules. These data show that intrinsic Epo and all ESAs can be detected by Western blot either directly in urine or after deglycosylation in blood, and that the kidney but not the liver is the main site of Epo production in control and severe hypoxia. Our method will make the tests for Epo doping and detection easy.

Independent or integrative processing approach of metabolite datasets from different biospecimens potentially affects metabolic pathway recognition in metabolomics.

In metabolomics studies, metabolic pathway recognition (MPR) is performed by software tools to screen out the significant pathways disturbed by diseases or reinstated by drugs. To achieve MPR, the significantly changed metabolites determined in different biospecimens (e.g. plasma and urine) are analyzed either independently (metabolites from each biospecimen as a dataset) or integratively (metabolites from all biospecimens as a dataset). However, whether the choice of these two processing approaches affects the results of MPR remains unknown. In this study, this issue was addressed by selecting evaluation of the effects of the herbal medicine Rehmanniae Radix (RR) on anemia and adrenal fatigue by UPLC-QTOF-MS/MS-based metabolomics as an example. The significant pathways disturbed by the modeling of anemia and adrenal fatigue and those reinstated by treatments with raw and processed RR were recognized using MetPA software tool (MetaboAnalyst 3.0), and compared by independent and integrative processing of the significantly changed metabolites determined in plasma and urine. The results showed that the two processing approaches could yield different impact values of pathways and thereby recognize different significant pathways. The differences appear to happen more easily when metabolites from different biospecimens shared the same metabolic pathway. Such pathway could be recognized as a significant pathway by integrative processing but could be excluded by independent processing due to the converged and dispersed importance contributions of the involved metabolites to MPR in the two processing approaches. This issue should concern researchers because MPR is crucial not only to understanding metabolomics data but also to guiding subsequent mechanistic research.

Repeated measures of prenatal phthalate exposure and maternal hemoglobin concentration trends: The Ma'anshan birth cohort (MABC) study.

A prospective cohort study of a Chinese population was conducted to investigate the relationship between prenatal phthalates exposure and maternal hemoglobin or anemia. Based on the Ma'anshan Birth Cohort study, 7 phthalate metabolites were quantified in spot pregnancy urine samples (n = 9263) from 3269 pregnant women during each trimester. The maternal hemoglobin concentrations were obtained from electronic medical records at the same three time points for each participant during pregnancy. Anemia was defined as a hemoglobin concentration below 110 g/L in pregnant women. Repeated measures and trimester-specific analyses were used to estimate the effects of phthalates exposure on maternal hemoglobin and anemia. The prevalence of anemia was 3.6%, 27.0%, and 26.5% during the first, second and third trimester, respectively. Repeated measures analysis showed that hemoglobin concentrations decreased by 0.55, 0.19, 0.57, 0.49, and 0.54 g/L with each 1 ln-transformed concentration increase of MBP, MBzP, MEHP, MEOHP, and MEHHP, respectively. Exposure to MMP, MBP, MEHP, MEOHP, and MEHHP increased the risk of anemia by 1.11-fold, 1.21-fold, 1.20-fold, 1.13-fold, and 1.16-fold, respectively. Trimester-specific regression models stratified by the sample collection time during pregnancy generated consistent results. This is the first study focusing on the effect of prenatal phthalate exposures on hemoglobin or anemia in pregnant Chinese women. We found that prenatal phthalates exposure not only decreased the concentrations of hemoglobin but also showed associations with the prevalence of anemia. Associations appeared stronger for the subsample representing women pregnant with a male fetus than those pregnant with a female fetus. Anemia remains a moderate public health problem in China, and effective measures should be implemented.

Whole blood and urine bioactive Hepcidin-25 determination using liquid chromatography mass spectrometry.

Hepcidin is a small cysteine-rich signaling peptide that regulates blood serum iron concentrations [1-4]. Patients with chronic inflammation are known to have elevated levels of hepcidin in their blood and urine and often suffer from anemia as a result [5-10]. Measuring and quantifying the amount of active hepcidin in blood and urine can help to determine the cause and severity of the anemia thereby helping physicians determine the correct course of treatment [11-16]. We have developed a simple technique to isolate, chemically modify, and concentrate hepcidin from blood and urine coupled to high-pressure liquid chromatography mass spectrometry that can accurately and reproducibly measure and quantify the active hormone.

Anemia in nephrotic syndrome: approach to evaluation and treatment.

Nephrotic syndrome is one of the most common glomerular diseases that affect in children. Complications may occur in nephrotic syndrome as a result of the disease itself as well as its treatment. Most of these complications result from excessive urinary protein losses, and control of proteinuria is the most effective treatment strategy. Anemia is one of the many complications seen in patients with persistent nephrotic syndrome and may occur as a result of excessive urinary losses of iron, transferrin, erythropoietin, transcobalamin and/or metals. This leads to a deficiency of substrates necessary for effective erythropoiesis, requiring supplementation in order to correct the anemia. Supplementation of iron and erythropoietin alone often does not lead to correction of the anemia, suggesting other possible mechanisms which need further investigation. A clear understanding of the pathophysiologic mechanisms of anemia in nephrotic syndrome is necessary to guide appropriate therapy, but only limited evidence is currently available on the precise etiologic mechanisms of anemia in nephrotic syndrome. In this review we focus on the current state of knowledge on the pathogenesis of anemia in nephrotic syndrome.

Evaluation of dilution and normalization strategies to correct for urinary output in HPLC-HRTOFMS metabolomics.

Reliable identification of features distinguishing biological groups of interest in urinary metabolite fingerprints requires the control of total metabolite abundance, which may vary significantly as the kidneys adjust the excretion of water and solutes to meet the homeostatic needs of the body. Failure to account for such variation may lead to misclassification and accumulation of missing data in case of less concentrated urine specimens. Here, different pre- and post-acquisition methods of normalization were compared systematically for their ability to recover features from liquid chromatography-mass spectrometry metabolite fingerprints of urine that allow distinction between patients with chronic kidney disease and healthy controls. Methods of normalization that were employed prior to analysis included dilution of urine specimens to either a fixed creatinine concentration or osmolality value. Post-acquisition normalization methods applied to chromatograms of 1:4 diluted urine specimens comprised normalization to creatinine, osmolality, and sum of all integrals. Dilution of urine specimens to a fixed creatinine concentration resulted not only in the least number of missing values, but it was also the only method allowing the unambiguous classification of urine specimens from healthy and diseased individuals. The robustness of classification could be confirmed for two independent patient cohorts of chronic kidney disease patients and yielded a shared set of 49 discriminant metabolite features. Graphical Abstract Dilution to a uniform creatinine concentration across urine specimens yields more comparable urinary metabolite fingerprints.

Evaluation of maternal early obstetric warning system (MEOWS chart) as a predictor of obstetric morbidity: a prospective observational study.

OBJECTIVES: Maternal Early Obstetric Warning System (MEOWS) chart adopted from CEMACH 2003-2005 report is based on the principle that abnormalities in physiological parameters precede critical illness. The 'track and trigger' of physiological parameters on this chart can aid in recognition of maternal morbidity at an early stage, ultimately halting the cascade of severe maternal morbidity and mortality. The objectives of our study were to evaluate MEOWS chart as a bedside screening tool for predicting obstetric morbidity and to correlate each physiological parameter individually with obstetric morbidity. STUDY DESIGN: It was a prospective observational study conducted in labour wards of Guru Teg Bahadur Hospital, Delhi, India from October 2012 to April 2014. Physiological parameters of 1065 study subjects (including pregnant women in labour >28 weeks of gestation and postpartum women up to 6 weeks after delivery) were recorded on MEOWS chart. A trigger was defined as a single markedly abnormal observation (red trigger) or the combination of two simultaneously mildly abnormal observation (two yellow triggers). Based on outcome at time of discharge, Category 1 (normal and recovered without morbidity) and Category 2 (recovered with morbidity or mortality) were defined. Chi-square and Fischer's exact test were used for comparison between two groups. Performance of MEOWS chart was evaluated using Exact's method. Relative risk of morbidity (odd's ratio) and 95% confidence interval was calculated for individual parameter. p<0.05 was considered as significant. RESULTS: Two-hundred and eighty-four (26.6%) women triggered to abnormal zones on these charts. One-hundred and seventy-seven (16.61%) fulfilled the criteria for obstetric morbidity. MEOWS chart was 86.4% sensitive, 85.2% specific with a positive and negative predictive value of 53.8% and 96.9% respectively for prediction of obstetric morbidity. Individual parameters of MEOWS chart also had a significant correlation (p<0.05) with obstetric morbidity. CONCLUSIONS: MEOWS chart emerged as a useful bedside screening tool for prediction of obstetric morbidity and should be used routinely in every obstetric unit. Strict monitoring and documentation of all the vital parameters should be fundamental part of any patient's assessment to pick up acute illness at very early stage and to make a difference in final outcome.

Laboratory use of hepcidin in renal transplant recipients.

Hepcidin is a small peptide with a critical role in cellular iron homeostasis, as it regulates utilization of stored iron and antimicrobial defense in inflammation (bacterial and fungal). Since it was isolated in 2000, and especially in the last decade, numerous studies aimed to evaluate the clinical use of plasma and urine hepcidin as a marker of anemia, especially anemia of chronic disease and post-transplant anemia (PTA). Hepcidin regulation is delicately tuned by two inflammatory pathways activated by interleukin-6 (IL-6) and bone morphogenic proteins (BMPs) and iron regulated pathway sensitive to circulating transferin-iron (TR-Fe) complex. BMP-mediated pathway and TR-Fe sensitive pathway seem to be connected by hemojuveline, a BMP co-factor that interacts with transferine receptor 2 (TRF2) in cases of high TR-Fe circulatory concentration. In addition to these regulatory mechanisms other regulators and signaling pathways are being extensively researched. Hepcidin has been identified as an important contributor to morbidity and mortality in end stage renal disease (ESRD) but no such association has jet been found in case of PTA. However, there is an association between higher doses of erythropoiesis-stimulating agents (ESA) and mortality in the posttransplant period and the assumption that hepcidin might play a role in ESA resistance in PTA. Thus the review's main goal was to summarize papers published on the association of hepcidin with PTA, give up-to-date information on hepcidin regulation and on potential therapeutics that optimize hepcidin regulation. We also compared the performances of tests for hepcidin determination and reviewed research on immunosuppressants' (IS) effect on hepcidin concentration.

Urine metabonomic study for blood-replenishing mechanism of Angelica sinensis in a blood-deficient mouse model.

This study aimed at determining the effects of Angelica sinensis (AS) on urinary metabolites in blood deficiency mice and exploring its replenishing blood mechanism. Gas chromatography-mass spectrometry (GC-MS) was applied to detect metabolites in the urine samples in different collection periods. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to investigate the differences in metabolic profiles among control group (CG), blood deficiency model group (MG), AS groups, and Colla Corii Asini group (CCAG). The potential biomarkers were identified based on the variable importance in the projection (VIP), T-test, and National Institute of Standards and Technology (NIST) and mass spectra library. The metabolites were analyzed using metabolomics pathway analysis (MetPA) to build the metabolic pathways. Our results indicated that, on the seventh day, the levels of glucose, lactic acid, pyruvic acid, alanine, acetoacetic acid, and citric acid changed significantly in blood deficiency mice. However, these metabolic deviations came to closer to normal levels after AS intervention. The reversing blood-deficiency mechanism of AS might involve regulating synthesis and degradation of ketone bodies, Pyruvate metabolism, TCA cycle, and Glycolysis/Gluconeogenesis. In conclusion, metabonomics is a robust and promising means for the identification of biomarkers and elucidation of the mechanisms of a disease, thereby highlighting its importance in drug discovery.

Urinary Vitamin D Binding Protein and KIM-1 Are Potent New Biomarkers of Major Adverse Renal Events in Patients Undergoing Coronary Angiography.

BACKGROUND: Vitamin-D-binding protein (VDBP) is a low molecular weight protein that is filtered through the glomerulus as a 25-(OH) vitamin D 3/VDBP complex. In the normal kidney VDBP is reabsorbed and catabolized by proximal tubule epithelial cells reducing the urinary excretion to trace amounts. Acute tubular injury is expected to result in urinary VDBP loss. The purpose of our study was to explore the potential role of urinary VDBP as a biomarker of an acute renal damage. METHOD: We included 314 patients with diabetes mellitus or mild renal impairment undergoing coronary angiography and collected blood and urine before and 24 hours after the CM application. Patients were followed for 90 days for the composite endpoint major adverse renal events (MARE: need for dialysis, doubling of serum creatinine after 90 days, unplanned emergency rehospitalization or death). RESULTS: Increased urine VDBP concentration 24 hours after contrast media exposure was predictive for dialysis need (no dialysis: 113.06 ± 299.61 ng/ml, n = 303; need for dialysis: 613.07 ± 700.45 ng/ml, n = 11, Mean ± SD, p<0.001), death (no death during follow-up: 121.41 ± 324.45 ng/ml, n = 306; death during follow-up: 522.01 ± 521.86 ng/ml, n = 8; Mean ± SD, p<0.003) and MARE (no MARE: 112.08 ± 302.00 ng/ml, n = 298; MARE: 506.16 ± 624.61 ng/ml, n = 16, Mean ± SD, p<0.001) during the follow-up of 90 days after contrast media exposure. Correction of urine VDBP concentrations for creatinine excretion confirmed its predictive value and was consistent with increased levels of urinary Kidney Injury Molecule-1 (KIM-1) and baseline plasma creatinine in patients with above mentioned complications. The impact of urinary VDBP and KIM-1 on MARE was independent of known CIN risk factors such as anemia, preexisting renal failure, preexisting heart failure, and diabetes. CONCLUSIONS: Urinary VDBP is a promising novel biomarker of major contrast induced nephropathy-associated events 90 days after contrast media exposure.

Urinary liver-type fatty acid-binding protein change in gestational diabetes mellitus.

We compared urinary liver-type fatty acid-binding protein (L-FABP) among non-pregnant and pregnant women with and without gestational diabetes mellitus (GDM). Higher urinary L-FABP was found in pregnant with and without GDM, and considerably higher urinary L-FABP was found in the GDM group compared with the non-GDM group. Hyperglycemia and anemia were related with high urinary L-FABP expression.

Distinct roles of urinary liver-type fatty acid-binding protein in non-diabetic patients with anemia.

BACKGROUND: Various stresses including ischemia are known to up-regulate renal L-FABP gene expression and increase the urinary excretion of L-FABP. In diabetic patients with anemia, the urinary excretion of L-FABP is significantly increased. We studied the clinical significance of urinary L-FABP and its relationship with anemia in non-diabetic patients. SUBJECTS AND METHODS: A total of 156 patients were studied in this retrospective cross-sectional analysis. The associations between anemia and urinary L-FABP levels, and the predictors of urinary L-FABP levels in non-diabetic patients were evaluated. RESULTS: Urinary L-FABP levels were significantly higher in patients with anemia compared to those in patients without anemia. Similarly, the urinary L-FABP levels were significantly higher in patients with albuminuria compared to those in patients without albuminuria. Urinary L-FABP levels correlated with urinary albumin-to-creatinine ratios, estimated glomerular filtration rates, body mass index, and hemoglobin levels. Multivariate linear regression analysis determined that hemoglobin levels (ß = -0.249, P = 0.001) and urinary albumin-to-creatinine ratios (ß = 0.349, P < 0.001) were significant predictors of urinary L-FABP levels. CONCLUSIONS: Urinary L-FABP is strongly associated with anemia in non-diabetic patients.