Urinary cystatin-C and urinary NGAL associated with sepsis predicts longer hospital stay in premature newborns.

Aim: To evaluate the urinary biomarkers related to sepsis in preterm newborns (NBs) and to investigate the predictive capacity of these biomarkers for a longer hospital stay.Methods: Serum and urine were collected from 27 healthy NBs, 24 NBs with neonatal infection without sepsis and 11 NBs with sepsis for the measurement of sindecan-1, lipocalin associated with urinary neutrophil gelatinase (uNGAL), urinary cystatin-C (uCysC) and urinary kidney injury molecule-1.Results: Levels of uNGAL and urinary cystatin-C were elevated in NBs with sepsis and neonatal infection, and uNGAL was significant predictor of hospital stay longer than 30 days (odds ratio: 1.052; 95% CI: 1.012-1.093; p = 0.01).Conclusion: uNGAL was associated with sepsis in preterm NBs and was useful to predict extended hospital stay.

[Box: see text].

Urine Biomarkers for the Assessment of Acute Kidney Injury in Neonates with Hypoxic Ischemic Encephalopathy Receiving Therapeutic Hypothermia.

OBJECTIVE: To evaluate the predictive performance of urine biomarkers for acute kidney injury (AKI) in neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia. STUDY DESIGN: We performed a multicenter prospective observational study of 64 neonates. Urine specimens were obtained at 12, 24, 48, and 72 hours of life and evaluated for neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), cystatin C, interleukin-18 (IL-18), tissue inhibitor of metalloproteinases 2 (TIMP2), and insulin-like growth factor-binding protein 7 (IGFBP7). Logistic regression models with receiver operating characteristics for area under the curve (AUC) were used to assess associations with neonatal modified KDIGO (Kidney Disease: Improving Global Outcomes) AKI criteria. RESULTS: AKI occurred in 16 of 64 infants (25%). Neonates with AKI had more days of vasopressor drug use compared with those without AKI (median [IQR], 2 [0-5] days vs 0 [0-2] days; P = .026). Mortality was greater in neonates with AKI (25% vs 2%; P = .012). Although NGAL, KIM-1, and IL-18 were significantly associated with AKI, the AUCs yielded only a fair prediction. KIM-1 had the best predictive performance across time points, with an AUC (SE) of 0.79 (0.11) at 48 hours of life. NGAL and IL-18 had AUCs (SE) of 0.78 (0.09) and 0.73 (0.10), respectively, at 48 hours of life. CONCLUSIONS: Urine NGAL, KIM-1, and IL-18 levels were elevated in neonates with HIE receiving therapeutic hypothermia who developed AKI. However, wide variability and unclear cutoff levels make their clinical utility unclear.

Cystatin C as an indicator of renal damage in pre-eclampsia.

OBJECTIVE: To assess the predictive abilities of serum and urinary cystatin C levels for glomerular lesions in pregnant women with pre-eclampsia. METHODS: In this study, kidney function markers were compared between38 pregnant women with pre-eclampsia and 22 healthy pregnant women. RESULTS: The serum and urine levels of cystatin C and urea were significantly higher in the pre-eclampsia group than in the control group. Receiver operating characteristic curve analysis demonstrated that the serum cystatin C level (91.7%) had a superior diagnostic accuracy for pre-eclampsia than the other markers. CONCLUSION: Serum cystatin C level maybe a significant marker of pre-eclampsia.

Evaluation of Benzene Exposure and Early Biomarkers of Kidney Damage in Children Exposed to Solvents Due to Precarious Work in Ticul, Yucatán, México.

BACKGROUND: The child labor situation has been associated with precarious job conditions and poor health conditions because children are often exposed to unsafe work environments, stressful psycho-social work conditions, scarce or no access to protective services, and heavy work burdens. OBJECTIVE: The aim of the study was to evaluate markers of exposure to benzene through the exposure biomarker trans, trans-muconic acid (tt-MA), and biomarkers of early renal damage in children who work in sites that are under precarious job conditions. METHOD: Samples of urine were obtained from children (aged 6-12 years old) who resided in Ticul, Yucatan, Mexico. Exposure to benzene was assessed through trans, trans-muconic acid (t,t-MA). Evaluated renal damage biomarkers were: Cystatin-C (Cys-C), Osteopontin (OPN), α1-Microglobulin (α1-MG) and Neutrophil Gelatinase-Associated Lipocalin (NGAL). FINDINGS: Children who live where the workplace is inside the dwelling presented higher mean levels of tt-MA (0.59 mg/g creatinine) compared with those who live away from the workshops (0.19 mg/g creatinine). Likewise, mean levels of NGAL (4.7, 5.2 ng/ml), albuminuria (10, 10 ng/ml), Cys-C (11.8, 7.5 ng/ml), OPN (224.4, 226.5 ng/ml) and α1-MG (96.6, 73.6 ng/ml) were found in children where the workplace was inside the dwelling and outside, respectively. CONCLUSION: Our data indicate that the children who work under precarious job conditions are exposed to benzene, and they exhibit protein levels that suggest renal damage in a population in precarious working conditions. Therefore, the child population should be considered as the most vulnerable and susceptible to suffer adverse health effects.

Evaluation of kidney injury biomarkers in an adult Mexican population environmentally exposed to fluoride and low arsenic levels.

Fluoride (F) is a toxicant widely distributed in the environment. Experimental studies have shown kidney toxicity from F exposure. However, co-exposure to arsenic (As) has not been considered, and epidemiological information remains limited. We evaluated the association between F exposure and urinary kidney injury biomarkers and assessed As co-exposure interactions. A cross-sectional study was conducted in 239 adults (18-77 years old) from three communities in Chihuahua, Mexico. Exposure to F was assessed in urine and drinking water, and As in urine samples. We evaluated the urinary concentrations of albumin (ALB), cystatin-C (Cys-C), kidney injury molecule 1 (KIM-1), clusterin (CLU), osteopontin (OPN), and trefoil factor 3 (TFF-3). The estimated glomerular filtration rate (eGFR) was calculated using serum creatinine (Creat) levels. We observed a positive correlation between water and urine F concentrations (ρ = 0.7419, p < 0.0001), with median values of 1.5 mg/L and 2 µg/mL, respectively, suggesting that drinking water was the main source of F exposure. The geometric mean of urinary As was 18.55 ng/mL, approximately 39% of the urine samples had As concentrations above the human biomonitoring value (15 ng/mL). Multiple linear regression models demonstrated a positive association between urinary F and ALB (ß = 0.56, p < 0.001), Cys-C (ß = 0.022, p = 0.001), KIM-1 (ß = 0.048, p = 0.008), OPN (ß = 0.38, p = 0.041), and eGFR (ß = 0.49, p = 0.03); however, CLU (ß = 0.07, p = 0.100) and TFF-3 (ß = 1.14, p = 0.115) did not show significant associations. No interaction with As exposure was observed. In conclusion, F exposure was related to the urinary excretion of early kidney injury biomarkers, supporting the hypothesis of the nephrotoxic role of F exposure.

Novel acute kidney injury biomarkers: their characteristics, utility and concerns.

Acute kidney injury (AKI) consists of a rapid renal function decline which usually increases serum urea and creatinine levels. Since kidney injury begins by inducing biological and molecular changes which evolve to cellular damage, biomarkers could be used as tools for monitoring early AKI appearance, and predicting its recovery. Among the main AKI biomarkers the neutrophil gelatinase-associated lipocalin, cystatin C, kidney injury molecule-1, monocyte chemotactic peptide-1, N-acetyl-ß-D-glucosaminidase, interleukin-18, liver-type fatty acid-binding protein, netrin-1, cycle arrest markers, endogenous ouabain, selenium-binding protein 1, and BPIFA2 marker, have been described. Even though novel biomarkers seem to be more helpful to early detect AKI and/or predict the need for renal replacement, and mortality compared to serum creatinine, more comprehensive studies are still required to determine their clinical utility.

Combined creatinine-cystatin C CKD-EPI equation significantly underestimates measured glomerular filtration rate in people with type 2 diabetes mellitus.

AIM: To evaluate the accuracy of creatinine and cystatin C (cysC) equations to estimate glomerular filtration rate (GFR) in type 2 diabetes mellitus (DM) patients and healthy adults. METHODS: Case-control study including 84 patients with type 2 DM and 100 healthy adults with measured GFR (mGFR)≥60mL/min/1.73m2. GFR was measured by 51Cr-EDTA and estimated (eGFR) by the following equations using creatinine, cysC or both markers: Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Caucasian Asian Pediatrics and Adults (CAPA), CKD-EPI creatinine-cystatin C (CKDEPI-CC), and CKD-EPI cystatin C (CKDEPIcysC). Agreement was evaluated by Bland & Altman analysis. RESULTS: Healthy individuals were 66% females, aged 38±14years; they presented mGFR 112±19mL/min/1.73m2 and eGFR by CKD-EPI, CKDEPI-CC, CKDEPIcysC and CAPA equations, respectively, 108±17, 102±15, 97±16 and 93±16mL/min/1.73m2. DM group were 50% females, aged 59±19years and presented mGFR 104±27 and eGFR 87±19, 80±18, 74±20 and 73±18mL/min/1.73m2, respectively. All equations significantly underestimated mGFR, excepting creatinine-based CKD-EPI in the healthy group. The performance was considerably worse for GFRs above 120mL/min/1.73m2. CONCLUSION: In both healthy and type 2 DM patients, cystatin C-based equations, including the combined CKD-EPI creatinine-cystatin equation, failed to improve the accuracy of GFR estimation, especially for normal and high normal GFR values.

Nested case-control study reveals increased levels of urinary proteins from human kidney toxicity panels in women predicted to develop preeclampsia.

PURPOSE: The aim of this study was to evaluate the usefulness of urine concentrations of 12 proteins as a risk parameter for developing preeclampsia (PE). METHODS: A nested case-control study was designed to determine protein concentrations in urine from women predicted to develop PE (WPD-PE) and normotensive pregnancies (controls). Protein profiles were determined at 12, 16 and 20 gestational weeks (GW) using the Bio-Plex Pro human kidney toxicity Panel 1 and Panel 2 (Bio-Rad). Receiver operating characteristic (ROC) curve analyses were performed. Correlations between proteins and clinical parameters at the time of PE diagnosis were also assessed. RESULTS: Significant differences were observed in urine cystatin C (Cys C) levels at 16 and 20 GW and clusterin at 20 GW between WPD-PE and controls (P < 0.05). ROC analysis revealed that Cys C at 16 GW had the highest area under the ROC curve (0.758). At 16 GW, patients with urine Cys C levels above 73.7 ng/mL had eightfold increased odds for developing PE (odds ratio 7.92; 95 % CI 1.3-47.5; P = 0.027). A positive correlation was found between urinary Cys C (at 16 and 20 GW) and leukocyte counts, total proteins, aspartate aminotransferase, alanine aminotransferase, bilirubin and lactate dehydrogenase at the time of PE diagnosis (P value < 0.05). CONCLUSIONS: Urinary Cys C and clusterin showed predictive value for PE development in our cohort. Further studies are needed to validate their use as predictive biomarkers for PE and/or their participation in PE pathogenesis.

Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D.

INTRODUCTION: Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting. OBJECTIVE: The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients. PATIENTS AND METHODS: We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation. Estimated glomerular filtration rate (eGFR) was estimated by serum cystatin C and creatinine. In addition, urinary electrolytes and tubular biomarkers (cystatin C, ß2-microglobulin and neutrophil gelatinase-associated lipocalin) were analyzed, as well as parathyroid hormone (PTH) and 25(OH)vitamin D levels. RESULTS: After 1 year, 32 patients completed the study, 22 (68.7%) men and 12 (37.5%) Whites, mean age 44.1±12.0 years. We found that serum electrolytes were similar at baseline and 3 or 12 months after initiation of TDF monotherapy. In addition, urinary fractional excretions of electrolytes as well as proteinuria, albuminuria, urinary ß2-microglobulin, and urinary cystatin C showed no significant differences across the treatment timeline. There were also no statistical differences in the eGFR. There was a statistically significant increase in the PTH (Friedman's test, P=0.012), but the 25(OH)vitamin D levels were in the normal range in the beginning and did not change at the follow-up. Moreover, there was no correlation between the initial levels of vitamin D and the corresponding increases in the PTH values. CONCLUSION: If used as monotherapy in hepatitis B patients for a 12-month period, TDF is not associated with changes in either eGFR or a panel of urinary biomarkers. Serum and urinary electrolytes also remained unchanged. Of note, a significant increase in the PTH was found, although not related to the 25(OH)vitamin D initial status.

Renal function is associated with peak exercise capacity in adolescents with type 1 diabetes.

OBJECTIVE: Diabetic nephropathy and cardiovascular disease are strongly related in adults with type 1 diabetes, yet little is known about this relationship in adolescents prior to the onset of detectable clinical disease. We hypothesized that cardiopulmonary fitness would be directly associated with albumin-to-creatinine ratio (ACR) and inversely related to estimated glomerular filtration rate (eGFR) in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: Sixty-nine adolescents with type 1 diabetes and 13 nondiabetic control subjects of similar pubertal stage and BMI had insulin sensitivity (glucose infusion rate [GIR]), measured by hyperinsulinemic-euglycemic clamp, and lean body mass, measured by DEXA. Cardiopulmonary fitness was measured by cycle ergometry to obtain peak volume of oxygen (VO2peak), and renal function was measured by eGFR using the Bouvet equation (measuring creatinine and cystatin C levels) and ACR. RESULTS: Adolescents (15.5 ± 2.2 years of age) with type 1 diabetes (6.3 ± 3.8 years diabetes duration) had reduced VO2peak (31.5 ± 6.3 vs. 36.2 ± 7.9 mL/kg ⋅ min, P = 0.046) and VO2peak/lean kg (43.7 ± 7.0 vs. 51.0 ± 8.6 mL/lean kg ⋅ min, P = 0.007) compared with nondiabetic control subjects. eGFR was inversely associated with VO2peak and VO2peak/lean kg after adjusting for sex, Tanner stage, GIR, HbA1c level, systolic blood pressure, and LDL cholesterol level (ß ± SE, VO2peak: -0.19 ± 0.07, P = 0.02; VO2peak/lean kg: -0.19 ± 0.09, P = 0.048). Moreover, participants in the highest tertile for eGFR had significantly lower sex- and Tanner-adjusted VO2peak and VO2peak/lean kg compared with participants in the lowest tertile. CONCLUSIONS: Adolescents with type 1 diabetes had reduced exercise capacity, which was strongly associated with renal health, independent of insulin sensitivity. Future studies should examine the underlying interrelated pathophysiology in order to identify probable targets for treatment to reduce cardiovascular and renal complications.

Urine protein biomarkers for the diagnosis and prognosis of necrotizing enterocolitis in infants.

OBJECTIVES: To test the hypothesis that an exploratory proteomics analysis of urine proteins with subsequent development of validated urine biomarker panels would produce molecular classifiers for both the diagnosis and prognosis of infants with necrotizing enterocolitis (NEC). STUDY DESIGN: Urine samples were collected from 119 premature infants (85 NEC, 17 sepsis, 17 control) at the time of initial clinical concern for disease. The urine from 59 infants was used for candidate biomarker discovery by liquid chromatography/mass spectrometry. The remaining 60 samples were subject to enzyme-linked immunosorbent assay for quantitative biomarker validation. RESULTS: A panel of 7 biomarkers (alpha-2-macroglobulin-like protein 1, cluster of differentiation protein 14, cystatin 3, fibrinogen alpha chain, pigment epithelium-derived factor, retinol binding protein 4, and vasolin) was identified by liquid chromatography/mass spectrometry and subsequently validated by enzyme-linked immunosorbent assay. These proteins were consistently found to be either up- or down-regulated depending on the presence, absence, or severity of disease. Biomarker panel validation resulted in a receiver-operator characteristic area under the curve of 98.2% for NEC vs sepsis and an area under the curve of 98.4% for medical NEC vs surgical NEC. CONCLUSIONS: We identified 7 urine proteins capable of providing highly accurate diagnostic and prognostic information for infants with suspected NEC. This work represents a novel approach to improving the efficiency with which we diagnose early NEC and identify those at risk for developing severe, or surgical, disease.

Análisis de anticuerpos antifosfolipídicos y cistatina C en pacientes con esclerosis múltiple / Analysis of antiphospholipid antibodies and cystatin C in multiple sclerosis patients / Teste de anticorpos antifosfolípídes e cistatina C em pacientes com esclerose múltipla

La cistatina C es considerada el inhibidor fisiológico más importante de las proteasas de cisteína endógenas. Se cree que el papel de la cistatina C es el de modular la actividad de las proteasas secretadas o liberadas de células dañadas o en proceso de necrosis, siendo por tanto las cistatinas fundamentales para los procesos de regulación y prevención del potencial daño proteolítico local. Los anticuerpos antifosfolípidos se usan para esclarecer el diagnóstico de esclerosis múltiple (EM) ya que existen patologías que pueden cursar con sintomatología o hallazgos paraclínicos semejantes. El objetivo de este trabajo fue analizar la concentración de cistatina C y la presencia o ausencia de anticuerpos antifosfolipídicos en pacientes diagnosticados de esclerosis múltiple remitente recurrente (EMRR) como marcadores de desmielinización. Este trabajo se llevó a cabo conjuntamente por el laboratorio de Riesgo Vascular, el laboratorio de Autoinmunidad y la Unidad de Esclerosis Múltiple del Hospital Universitario Virgen Macarena de Sevilla, España, con una duración de un año. Se seleccionaron dos tipos de poblaciones: grupo 1, n=30 pacientes con EMRR y un segundo grupo, denominado grupo control, n=30. Se determinó cistatina C y anticuerpos antifosfolípidos IgG e IgM, anticuerpos anticardiolipina IgG e IgM y anticuerpos f>2 glicoproteína IgG e IgM. Los pacientes diagnosticados de EMRR presentan títulos negativos de anticuerpos antifosfolípidos IgG e IgM, anticardiolipina IgG e IgM y f>2 glicoproteína IgG e IgM. La concentración de cistatina C es menor en el grupo de pacientes diagnosticados de EM, lo que podría producir un déficit en la modulación de las proteasas de cisteína endógenas. Dicha desmielini-zación agudizaría el progreso de la EM.

Cystatin C is considered the most important physiological inhibitor of endogenous cysteine proteases; the role of cystatin C is believed to be to modulate the activity of proteases secreted or released from damaged cells or in the process of necrosis, therefore cystatins being fundamental regulatory processes and a potential prevention of local proteolytic damage. Antiphospholipid antibodies are used to clarify the diagnosis of diseases like multiple sclerosis (MS) and other pathologies could present similai symptoms or paraclinical findings. The objective of the present work is to analyze the concentration of cystatin C and the presence or absence of antiphospholipid antibodies in patients diagnosed with relapsing remitting multiple sclerosis (RRMS) as markers of demyelization. This work was carried out jointly by the Vascular Risk Laboratory, the Laboratory of Autoimmunity and Multiple Sclerosis Unit, Hospital Universitario Virgen Macarena in Seville in one year. Two types of people were selected: Group 1 (n = 30) RRMS group and a control group, n = 30. Cystatin C and antiphospholipid antibodies IgG and IgM, IgG and IgM anticardiolipin, $2 glycoprotein IgG and IgM were determined. Patients showed negative titers of antiphospholipid antibodies IgG and IgM, IgG and IgM anticardiolipin, $2 glycoprotein IgG and IgM. Cystatin C concentration is lower in the group of patients diagnosed with MS, which could give rise to a decrease in the modulation of endogenous cysteine proteases. This would exacerbate the progress of demyelization in MS.

A cistatina C é considerada o inibidor fisiológico das proteases de cisteína endógenas mais importante. Acredita-se que o papel da cistatina C é o de modular a atividade de proteases secretadas ou liberadas a partir de células danificadas ou em processo de necrose, sendo por isso as cistatinas fundamentais para os processos de regulagao e prevengao do potencial dano proteolítico local. Anticorpos antifosfolípides sao usados para esclarecer o diagnóstico de EM, visto que existem patologias que podem apresentar sintomas ou achados paraclínicos semelhantes. O objetivo deste trabalho foi o de analisar a concentra-gao de cistatina C e a presenga ou ausencia de anticorpos antifosfolípides em pacientes diagnosticados com esclerose múltipla recidivante - remitente (EMRR) como marcadores de desmielinizagao. Este trabalho foi realizado em conjunto pelo laboratório de Risco Vascular, o laboratório de Autoimunidade e a Unidade de Esclerose Múltipla do Hospital Universitario Virgen Macarena, de Sevilha, Espanha, com uma duragao de um ano. Foram selecionados dois tipos de populagdes-. Grupo 1 (n = 30) pacientes com EMRR e um segundo grupo, chamado de grupo controle, n = 30. Determinou-se cistatina C e anticorpos antifosfolípides IgG e IgM, anticorpos anticardiolipina IgG e IgM, e anticorpos $2 glicoproteína IgG e IgM. Pacientes diagnosticados com EMRR apresentam títulos negativos de anticorpos antifosfolípides IgG e IgM, anticardiolipina IgG e IgM e $2 glicoproteína IgG e IgM. A concentragao de cistatina C é menor no grupo de pacientes diagnosticados com EM, o que poderia produzir um déficit na modulagao das proteases de cisteína endógenas. Tal desmielinizagao agravaría o progresso da EM.

Are recently reported biomarkers helpful for early and accurate diagnosis of acute kidney injury?

Over the past few years and with the use of innovative genomic and proteomic tools, several molecules that their urinary concentration is modified during acute kidney injury have been identified and proposed as biomarkers. Among the most studied biomarkers are neutrophil gelatinase-associated lipocalin-2, kidney injury molecule-1, interleukin-18, cystatin C, N-acetyl-ß-D-glucosaminidase, liver fatty-acid binding protein, and heat shock protein 72. Here, we reviewed and compared the sensitivity and specificity of each biomarker for the appropriate diagnosis of acute kidney injury, as well as its ability to stratify renal injury and to monitor a renoprotective pharmacologic strategy.

Urine biomarkers predict acute kidney injury in newborns.

OBJECTIVE: To identify urine biomarkers predictive of acute kidney injury (AKI) in infants admitted to level 2 and 3 neonatal intensive care units with birth weight >2000 g and 5-minute Apgar score ≤ 7. STUDY DESIGN: A nested case-control study was performed comparing 8 candidate urine AKI biomarkers in infants with AKI (defined as a rise in serum creatinine of at least 0.3 mg/dL or a serum creatinine elevation ≥ 1.7 mg/dL persisting for 3 days) and 24 infants from the described cohort without AKI. Urine was analyzed for neutrophil gelatinase-associated lipocalin, osteopontin, cystatin C, albumin, ß(2) microglobulin, epithelial growth factor, uromodulin (UMOD), and kidney injury molecule 1. RESULTS: Compared with the infants without AKI, those with AKI had higher levels of urine cystatin C (1123 pg/mL [95% CI, 272-4635 pg/mL] vs 90 pg/mL [95% CI, 39-205 pg/mL]; P < .004; area under the receiver operating characteristic curve [AUC] = 0.82), lower levels of UMOD (11.0 pg/mL [95% CI, 5.7-21.4 pg/mL] vs 26.2 pg/mL [95% CI, 17.4-39.4 pg/mL]; P < .03; AUC = 0.77), and lower levels of epithelial growth factor (6.7 pg/mL [95% CI, 4.0-11.3 pg/mL] vs 17.4 pg/mL [95% CI, 12.7-23.8 pg/mL; P = .003; AUC = 0.82). Although the differences were not statistically significant, levels of urine neutrophil-associated gelatinase lipocalin, kidney injury molecule 1, and osteopontin trended higher in infants with AKI. CONCLUSION: Urinary biomarkers can predict AKI in neonates admitted to level 2 and 3 neonatal intensive care units.