Novel predictive biomarkers for acute injury superimposed on chronic kidney disease / Novedosos biomarcadores predictivos para lesiones agudas superpuestas a una enfermedad renal crónica

INTRODUCTION AND OBJECTIVES: Chronic kidney disease (CKD) is a risk factor for the development of acute kidney injury (AKI). Recent studies have revealed numerous biomarkers eligible for AKI prediction. However, the expression and performance of AKI biomarkers in acute injury superimposed on preexisting CKD (AonC) remain elusive. The aim of this study was to evaluate whether biomarkers which robustly expressed in acute kidney injury could predict acute injury based on CKD. MATERIALS AND METHODS: Mice were classified into cohorts: AKI, CKD, AonC and sham. The AonC model mice were subjected to renal bilateral ischemia/reperfusion (I/R) injury fourteen days after intraperitoneally administrated with 20 mg/kg aristolochic acid. Severity of acute ischemic injury was stratified by clamping the dissected bilateral renal arteries with non-traumatic microvascular clips for 20 or 35 min. The AKI mice were induced with renal bilateral I/R injury and CKD mice were crafted with 20mg/kg aristolochic acid administrated intraperitoneally. Histology, genetic and protein expression of biomarkers were measured in three cohorts. RESULTS: We found that serum creatinine dramatically increased in severe (sAonC) but not in moderate (mAonC) injury mice. Upregulation of Kidney injury molecule-1 (KIM-1) mRNA, tissue inhibitor of metalloproteinase-2 (TIMP-2), Syndecan-1 (SDC-1) mRNA and insulin-like growth factor binding protein-7 (IGFBP7) protein indicated the onset of mAonC. An increase in neutrophil gelatinase-associated lipocalin (NGAL), rhomboid-like protein 2 (RHBDL2), Syndecan-1 (SDC-1) mRNA and protein, and a decrease in IGFBP7 protein were associated with sAonC. CONCLUSIONS: Our study revealed the variational expression of AKI biomarkers in AonC kidneys, and uncovered IGFBP7 protein can be used as a sensitive biomarker to predict and differentiate AonC severity. The performance of RHBDL2 and SDC-1 in predicting severe AonC was promising, providing new biomarkers for predicting AonC

INTRODUCCIÓN Y OBJETIVOS: La enfermedad renal crónica (ERC) es un factor de riesgo para el desarrollo de una lesión renal aguda (LRA). Estudios recientes han revelado numerosos biomarcadores para la predicción de LRA. No obstante, la expresión y el rendimiento de los biomarcadores de LRA en lesiones agudas superpuestas a una ERC preexistente (AonC, en inglés) siguen siendo imprecisos. El objetivo de este estudio fue evaluar si los biomarcadores que se encuentran muy expresados en la lesión renal aguda podrían predecir una lesión aguda superpuesta a una ERC. MATERIALES Y MÉTODOS: Se dividieron ratones en cohortes (LRA, ERC, AonC y grupo de referencia). A los ratones del modelo de AonC se les indujo una lesión renal bilateral por isquemia/reperfusión (I/R) 14 días después de la administración intraperitoneal de 20 mg/kg de ácido artistolóquico. La gravedad de la lesión isquémica aguda se estratificó pinzando las arterias renales bilaterales diseccionadas con horquillas microvasculares no traumáticas durante 20 o 35 min. A los ratones de LRA se les indujo una lesión renal bilateral por I/R y a los ratones de ERC se les administraron 20mg/kg de ácido artistolóquico por vía intraperitoneal. Se determinaron la histología, la genética y la expresión de proteínas en las tres cohortes. RESULTADOS: Observamos que la creatinina sérica aumentaba drásticamente en los ratones con lesiones graves (AonCg) pero no en aquellos con lesiones moderadas (AonCm) El aumento del ARNm de la molécula1 de lesión renal (KIM-1), del inhibidor tisular de metaloproteinasas 2 (TIMP-2), del ARNm de sindecán 1 (SDC-1) y de la proteína de unión al factor de crecimiento insulinoide 7 (IGFBP7) fue indicativo de aparición de AonCm. El incremento de la lipocalina asociada a la gelatinasa de neutrófilos (NGAL), la proteína romboidal 2 (RHBDL2) y el ARNm y la proteína de sindecán 1 (SDC-1), así como la reducción de la proteína IGFBP7, se asociaron a una AonCg. CONCLUSIONES: Nuestro estudio mostró la variación de la expresión de los biomarcadores de LRA en riñones con AonC y descubrió que la proteína IGFBP7 puede emplearse como biomarcador sensible para la predicción y la diferenciación de la gravedad de la AonC. El rendimiento de RHBDL2 y SDC-1 en la predicción de AonC graves resultó prometedor, lo que ofrece nuevos biomarcadores para la predicción de AonC

Urine cell cycle arrest biomarkers distinguish poorly between transient and persistent AKI in early septic shock: a prospective, multicenter study.

BACKGROUND: The urine biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) have been validated for predicting and stratifying AKI. In this study, we analyzed the utility of these biomarkers for distinguishing between transient and persistent AKI in the early phase of septic shock. METHODS: We performed a prospective, multicenter study in 11 French ICUs. Patients presenting septic shock, with the development of AKI within the first 6 h, were included. Urine [TIMP-2]*[IGFBP7] was determined at inclusion (0 h), 6 h, 12 h, and 24 h. AKI was considered transient if it resolved within 3 days. Discriminative power was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: We included 184 patients, within a median [IQR] time of 1.0 [0.0-3.0] h after norepinephrine (NE) initiation; 100 (54%) patients presented transient and 84 (46%) presented persistent AKI. Median [IQR] baseline urine [TIMP-2]*[IGFBP7] was higher in the persistent AKI group (2.21 [0.81-4.90] (ng/ml)2/1000) than in the transient AKI group (0.75 [0.20-2.12] (ng/ml)2/1000; p < 0.001). Baseline urine [TIMP-2]*[IGFBP7] was poorly discriminant, with an AUROC [95% CI] of 0.67 [0.59-0.73]. The clinical prediction model combining baseline serum creatinine concentration, baseline urine output, baseline NE dose, and baseline extrarenal SOFA performed well for the prediction of persistent AKI, with an AUROC [95% CI] of 0.81 [0.74-0.86]. The addition of urine [TIMP-2]*[IGFBP7] to this model did not improve the predictive performance. CONCLUSIONS: Urine [TIMP-2]*[IGFBP7] measurements in the early phase of septic shock discriminate poorly between transient and persistent AKI and do not improve clinical prediction over that achieved with the usual variables. TRIAL REGISTRATION: NCT02812784.

Clinical use of [TIMP-2]•[IGFBP7] biomarker testing to assess risk of acute kidney injury in critical care: guidance from an expert panel.

BACKGROUND: The first FDA-approved test to assess risk for acute kidney injury (AKI), [TIMP-2]•[IGFBP7], is clinically available in many parts of the world, including the USA and Europe. We sought to understand how the test is currently being used clinically. METHODS: We invited a group of experts knowledgeable on the utility of this test for kidney injury to a panel discussion regarding the appropriate use of the test. Specifically, we wanted to identify which patients would be appropriate for testing, how the results are interpreted, and what actions would be taken based on the results of the test. We used a modified Delphi method to prioritize specific populations for testing and actions based on biomarker test results. No attempt was made to evaluate the evidence in support of various actions however. RESULTS: Our results indicate that clinical experts have developed similar practice patterns for use of the [TIMP-2]•[IGFBP7] test in Europe and North America. Patients undergoing major surgery (both cardiac and non-cardiac), those who were hemodynamically unstable, or those with sepsis appear to be priority patient populations for testing kidney stress. It was agreed that, in patients who tested positive, management of potentially nephrotoxic drugs and fluids would be a priority. Patients who tested negative may be candidates for "fast-track" protocols. CONCLUSION: In the experience of our expert panel, biomarker testing has been a priority after major surgery, hemodynamic instability, or sepsis. Our panel members reported that a positive test prompts management of nephrotoxic drugs as well as fluids, while patients with negative results are considered to be excellent candidates for "fast-track" protocols.

Predictive value of cell cycle arrest biomarkers for cardiac surgery-associated acute kidney injury: a meta-analysis.

BACKGROUND: A biomarker test based on a combination of urine tissue inhibitor of metalloproteinases 2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) has been used as a potential biomarker of acute kidney injury (AKI). This meta-analysis aimed to evaluate the predictive value of this biomarker for cardiac surgery-associated acute kidney injury (CSA-AKI). METHODS: We searched MEDLINE, PubMed, Cochrane, and EMBASE for studies. We evaluated the methodological quality of each included study using the Quality Assessment of Diagnostic Accuracy Studies 2 criteria. Meta-DiSc and STATA were used for statistical analyses. RESULTS: A total of 10 studies (747 patients) were included in this meta-analysis. Pooled sensitivity and specificity with corresponding 95% confidence intervals (CI) were 0.77 (95% CI: 0.70-0.83, I2=40.7%) and 0.76 (95% CI: 0.72-0.79, I2=69.1%), respectively. Pooled positive likelihood ratio (LR), negative LR, and diagnostic odds ratio were 3.26 (95% CI: 2.51-4.23, I2=50.7%), 0.32 (95% CI: 0.24-0.41, I2=6.7%), and 10.08 (95% CI: 6.85-14.84, I2=6.7%), respectively. The area under the curve estimated by summary receiver operating characteristics was 0.83 [standard error (SE) 0.023] with a Q* value of 0.759 (se 0.021). There was no heterogeneity amongst the 10 studies from both threshold and non-threshold effects. Subgroup analysis showed that the diagnostic value was related to the severity of AKI and time measurement. CONCLUSIONS: Urinary [TIMP-2]·[IGFBP7] is an effective predictive test for cardiac surgery associated acute kidney injury with good diagnostic accuracy within 24 h. Studies examining use of biomarker-guided care bundles are indicated.

Postoperative cellular stress in the kidney is associated with an early systemic γδ T-cell immune cell response.

BACKGROUND: Basic science data suggest that acute kidney injury (AKI) induced by ischemia-reperfusion injury (IRI) is an inflammatory process involving the adaptive immune response. Little is known about the T-cell contribution in the very early phase, so we investigated if tubular cellular stress expressed by elevated cell cycle biomarkers is associated with early changes in circulating T-cell subsets, applying a bedside-to-bench approach. METHODS: Our observational pilot study included 20 consecutive patients undergoing endovascular aortic repair for aortic aneurysms affecting the renal arteries, thereby requiring brief kidney hypoperfusion and reperfusion. Clinical-grade flow cytometry-based immune monitoring of peripheral immune cell populations was conducted perioperatively and linked to tubular cell stress biomarkers ([TIMP-2]•[IGFBP7]) immediately after surgery. To confirm clinical results and prove T-cell infiltration in the kidney, we simulated tubular cellular injury in an established mouse model of mild renal IRI. RESULTS: A significant correlation between tubular cell injury and a peripheral decline of γδ T cells, but no other T-cell subpopulation, was discovered within the first 24 hours (r = 0.53; p = 0.022). Turning to a mouse model of kidney warm IRI, a similar decrease in circulating γδ T cells was found and concomitantly was associated with a 6.65-fold increase in γδ T cells (p = 0.002) in the kidney tissue without alterations in other T-cell subsets, consistent with our human data. In search of a mechanistic driver of IRI, we found that the damage-associated molecule high-mobility group box 1 protein HMGB1 was significantly elevated in the peripheral blood of clinical study subjects after tubular cell injury (p = 0.019). Correspondingly, HMGB1 RNA content was significantly elevated in the murine kidney. CONCLUSIONS: Our investigation supports a hypothesis that γδ T cells are important in the very early phase of human AKI and should be considered when designing clinical trials aimed at preventing kidney damage. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01915446 . Registered on 5 Aug 2013.

TIMP-2/IGFBP7 predicts acute kidney injury in out-of-hospital cardiac arrest survivors.

BACKGROUND: Acute kidney injury (AKI) is a common complication after cardiopulmonary resuscitation (CPR) and predicts in-hospital mortality. To which extent post-resuscitation disease or the initial event of cardiac arrest and the duration of insufficient cardiac output triggers AKI is challenging to discriminate. Knowledge on molecular mediators of AKI is scarce. Early identification of patients at high risk of AKI is hampered by the low sensitivity of the established tests in clinical routine practice. The present study aimed to determine the diagnostic utility of the novel urine biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) for the early recognition of AKI in patients with non-traumatic shock. METHODS: The performance of [TIMP-2]·[IGFBP7] was prospectively analysed in 48 patients with shock following out-of-hospital cardiac arrest (OHCA). All patients were treated with target temperature management (TTM) for 24 h. Urinary [TIMP-2]·[IGFBP7] samples were collected at 3 and 24 h after determination of OHCA. RESULTS: Patients (n = 31 (65%)) developed AKI after an average of 26 ± 12 h. Patients who developed AKI had significantly higher [TIMP-2]·[IGFBP7] compared to individuals that did not develop AKI (1.52 ± 0.13 vs. 0.13 ± 0.14; p < 0.05) as early as 3 h after determination of OHCA,. For urine [TIMP-2]*[IGFBP7], the area under the curve (AUC) for the development of AKI was 0.97 (CI 0.90-1.00) at 3 h after OHCA. The optimal [TIMP-2]·[IGFBP7] cut-off value for the prediction of AKI was 0.24. The sensitivity was 96.8% and specificity was 94.1%. CONCLUSIONS: Urinary [TIMP-2]•[IGFBP7] reliably predicts AKI in high-risk patients only 3 h after determination of OHCA with a cut-off at 0.24. This novel test may help to identify patients at high risk of AKI to enrol into clinical studies to further elucidate the pathophysiology of AKI and devise targeted interventions in the future.

Functional analysis of the IGF-system in milk.

The development of milk during evolution is considered a more recent step to provide the neonate with adequate amounts of energy, nutrients, and specific hormonal signals thereby, granting a fast and efficient rate of postnatal growth and development. Since the insulin- or the insulin-like growth factor (IGF) systems were evolved much earlier, it can be assumed that the functionality of the IGF-system has been integrated into the novel matrix milk containing casein and whey proteins from the beginnings. In fact, IGFs and IGF-binding proteins (IGFBPs) are abundantly present in milk, which is particularly true for fore-milk or colostrum and the potential effects of milk-borne IGF-compounds on the consuming organisms have in fact been addressed by several studies. Those studies examined, if orally administered IGFs can be absorbed by the consumer's gastro-intestinal tract and thus contribute e.g. to the somatic growth of infants. A second line of studies assessed local effects of milk-borne IGFs on growth and development of the gastro-intestinal tract itself. Finally, distinct functions of isolated IGF-compounds for growth and involution of the mammary gland have also been provided in the past. While the consumption of milk seems not to represent a major source of endogenous IGFs, accumulating evidence indicates secondary effects of milk on the endogenous IGF-system, which may be mediated by micronutrients such as branched amino acids and metabolic programming. By contrast, direct effects on growth and development of oesophageal and intestinal cells have been observed if IGFs were administered orally.

Routine adoption of TIMP2 and IGFBP7 biomarkers in cardiac surgery for early identification of acute kidney injury.

BACKGROUND AND PURPOSE: Acute Kidney Injury (AKI) is a severe complication affecting many hospitalized patients after cardiac surgery, with negative impacts on short- and long-term clinical outcomes and on healthcare costs. Recently, clinical interest has been aimed at defining and classifying AKI, identifying risk factors and developing diagnostic strategies to identify patients at risk early on. Achieving an early and accurate diagnosis of AKI is a crucial issue, because prevention and timely detection may help to prevent negative clinical outcomes and avoid AKI-associated costs. In this retrospective study, we evaluate the NephroCheck Test as a diagnostic tool for early detection of AKI in a high-risk population of patients undergoing cardiac surgery at the San Bortolo Hospital of Vicenza. METHODS: We assessed the ability of the NephroCheck Test to predict the probability of developing CSA-AKI (cardiac surgery-associated AKI) and evaluated its accuracy as a diagnostic test, by building a multivariate logistic regression model for CSA-AKI prediction. RESULTS: Based on our findings, when the results of the NephroCheck Test are included in a multivariate model its performance is substantially improved, as compared to the benchmark model, which only accounts for the other clinical factors. We also define a rule - in terms of a probability cut-off - for discriminating cases that are at higher risk of developing AKI of any stage versus those in which AKI is less likely. CONCLUSIONS: Our study has implications in clinical practice: when a Nephrocheck Test result is >0.3 ng/dL, an automated electronic alert prompts the physician to intervene by following a checklist of preventive measures.

Analysis of the IGF-system in milk from farm animals - Occurrence, regulation, and biomarker potential.

IGFs and IGF-binding proteins (IGFBPs) are abundantly present in milk and in dairy products. Compared to the IGFs, the IGFBP have received less attention in milk, although truncated IGFBPs and IGFBP-glycosylation have been described in milk. Thereby, complex control of local IGF-effects can be assumed on the levels of IGFBPs, proteases, and protease inhibitors. The present review collects the current knowledge both on presence and regulation of IGFs and IGFBPs in milk particularly from dairy animal species. As a rule higher levels of IGF-I, IGF-II, and IGFBPs are measured around parturition if compared to later time-points of lactation. In all farm animal species included in this review, it is found that the relative abundancies of IGFBPs in milk and serum are similar, with IGFBP-3 and -2 characterized by higher concentrations if compared to IGFBP-4 or -5. The concentrations of IGFs and IGFBPs in milk or dairy products can be altered by hormones, dairy processing, or fermentation. Because milk can be used for non-invasive biomarker research, quality management, and health monitoring, we discuss novel directions of IGF-analysis and potential on-site biomarker research in milk.

Diagnostic value of urinary tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for acute kidney injury: a meta-analysis.

BACKGROUND: Tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7), inducers of G1 cell cycle arrest, are two recently discovered good biomarkers for early diagnosis of acute kidney injury (AKI). To obtain a more robust performance measurement, the present meta-analysis was performed, pooling existing studies. METHODS: Literature in the MEDLINE (via PubMed), Ovid, Embase, and Cochrane Library databases was systematically searched from inception to 12 October 2016. Studies that met the set inclusion and exclusion criteria were identified by two independent investigators. The diagnostic value of urinary [TIMP-2] × [IGFBP7] for AKI was evaluated by pooled sensitivity, specificity, likelihood ratio (LR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curve analyses. The causes of heterogeneity were explored by sensitivity and subgroup analyses. RESULTS: A total of nine published and eligible studies assessing 1886 cases were included in this meta-analysis. Early diagnostic value of urinary [TIMP-2] × [IGFBP7] for AKI was assessed using a random-effects model. Pooled sensitivity and specificity with corresponding 95% CIs were 0.83 (95% CI 0.79-0.87, heterogeneity I 2 = 68.8%) and 0.55 (95% CI 0.52-0.57, I 2 = 92.9%), respectively. Pooled positive LR, negative LR, and DOR were 2.37 (95% CI 1.87-2.99, I 2 = 82.6%), 0.30 (95% CI 0.21-0.41, I 2 = 43.4%), and 9.92 (95% CI 6.09-16.18, I 2 = 38.5%), respectively. The AUC estimated by SROC was 0.846 (SE 0.027) with a Q* value of 0.777 (SE 0.026). Sensitivity analysis indicated that one study significantly affected the stability of pooled results. Subgroup analysis showed that population setting and AKI threshold were the key factors causing heterogeneity in pooled sensitivity and specificity. CONCLUSIONS: On the basis of recent evidence, urinary [TIMP-2] × [IGFBP7] is an effective predictive factor of AKI. TRIAL REGISTRATION: PROSPERO registration number: CRD42016051186 . Registered on 10 November 2016.

Diagnosis of cardiac surgery-associated acute kidney injury from functional to damage biomarkers.

PURPOSE OF REVIEW: Acute kidney injury (AKI) occurs in up to 30% after cardiac surgery and is associated with adverse outcome. Currently, cardiac surgery-associated acute kidney injury (CSA-AKI) is diagnosed by Kidney Disease: Improving Global Outcomes criteria based on creatinine and urine output. To detect and treat AKI earlier, various biomarkers have been evaluated. This review addresses the current position of the two damage biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and [TIMP-2] [IGFBP7] in clinical practice. RECENT FINDINGS: We present an updated review on the use of blood and urinary NGAL in CSA-AKI. NGAL is a good predictor, and performs better in children than adults. There is a large variation in predictive ability, possibly caused by diversity of AKI definitions used, different time of measurement of NGAL, and lack of specificity of NGAL assays.Similarly, there are conflicting data on the predictive ability of urinary [TIMP-2] [IGFBP7] for CSA-AKI.Recently, both for NGAL and for urinary [TIMP-2] [IGFBP7], a set of actions, based on pretest assessment of risk for CSA-AKI and biomarker test results, was developed. These scores should be evaluated in prospective trials. SUMMARY: NGAL and urinary [TIMP-2] [IGFBP7], in combination with pretest assessment, are promising tools for early detection and treatment in CSA-AKI.

Urine biomarkers give early prediction of acute kidney injury and outcome after out-of-hospital cardiac arrest.

BACKGROUND: Post-resuscitation care after out-of-hospital cardiac arrest (OHCA) is challenging due to the threat of organ failure and difficult prognostication. Our aim was to examine whether urine biomarkers could give an early prediction of acute kidney injury (AKI) and outcome. METHODS: This was a prospective observational study of comatose OHCA patients at Oslo University Hospital Ullevål, Norway. Risk factors were clinical parameters and biomarkers measured in spot urine (cystatin C, neutrophil gelatinase-associated lipocalin (NGAL) and the product of tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7)) at admission and day 3. Outcome variables were AKI within 3 days using the Kidney Disease Improving Global Outcomes definition, 6-month mortality, and poor neurological outcome (PNO) defined as cerebral performance category 3-5. RESULTS: Among 195 included patients (85 % males, mean age 60 years), 88 (45 %) died, 96 (49 %) had PNO, and 88 (45 %) developed AKI. In univariate analysis, increased urine cystatin C and NGAL concentration sampled at admission and day 3 were independent risk factors for AKI, mortality and PNO. Increased urine TIMP-2 × IGFBP7 levels was associated with AKI only at admission. In multivariate analyses combining clinical parameters and biomarker concentrations, the area under the receiver operating characteristics curve (AuROC) with 95 % confidence interval (CI) were 0.774 (0.700-0.848), 0.812 (0.751-0.873), and 0.819 (0.759-0.878) for AKI, mortality and PNO, respectively. CONCLUSIONS: In comatose OHCA patients, urine levels of cystatin C and NGAL at admission and day 3 were independent risk factors for AKI, 6-month mortality and PNO. TRIAL REGISTRATION: Clinicaltrials.gov NCT01239420 . Registered 10 November 2010.

Urinary Tissue Inhibitor of Metalloproteinase-2 and Insulin-Like Growth Factor-Binding Protein 7 for Risk Stratification of Acute Kidney Injury in Patients With Sepsis.

OBJECTIVES: To examine the performance of the urinary biomarker panel tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 in patients with sepsis at ICU admission. To investigate the effect of nonrenal organ dysfunction on tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 in this population. METHOD: In this ancillary analysis, we included patients with sepsis who were enrolled in either of two trials including 39 ICUs across Europe and North America. The primary endpoint was moderate-severe acute kidney injury (equivalent to Kidney Disease Improving Global Outcome stage 2-3) within 12 hours of enrollment. We assessed biomarker performance by calculating the area under the receiver operating characteristic curve, sensitivity, specificity, and negative and positive predictive values at three cutoffs: 0.3, 1.0, and 2.0 (ng/mL)/1,000. We also calculated nonrenal Sequential Organ Failure Assessment scores for each patient on enrollment and compared tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 results in patients with and without acute kidney injury and across nonrenal Sequential Organ Failure Assessment scores. Finally, we constructed a clinical model for acute kidney injury in this population and compared the performance of the model with and without tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7. RESULTS: We included 232 patients in the analysis and 40 (17%) developed acute kidney injury. We observed significantly higher urine tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 in patients with acute kidney injury than without acute kidney injury in both patients with low and high nonrenal Sequential Organ Failure Assessment scores (p < 0.001). The area under the receiver operating characteristic curve (95% CI) of tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 was 0.84 (0.73-0.92) and 0.85 (0.76-0.94), in low and high nonrenal Sequential Organ Failure Assessment score subgroups. Performance of the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 test was not modified by nonrenal Sequential Organ Failure Assessment (p = 0.70). In multivariate analysis, the addition of tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 significantly improved the performance of a clinical model for predicting acute kidney injury (p = 0.015). CONCLUSION: Urinary tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 accurately predicts acute kidney injury in septic patients with or without other organ failures.

Clinical adjudication in acute kidney injury studies: findings from the pivotal TIMP-2*IGFBP7 biomarker study.

BACKGROUND: The NEPROCHECK test (Astute Medical, San Diego, CA, USA) combines urinary tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) to identify patients at high risk for acute kidney injury (AKI). In a US Food and Drug Administration registration trial (NCT01573962), AKI was determined by a three-member clinical adjudication committee. The objectives were to examine agreement among adjudicators as well as between adjudicators and consensus criteria for AKI and to determine the relationship of biomarker concentrations and adjudicator agreement. METHODS: Subjects were classified as AKI 3/3, 2/3, 1/3 or 0/3 according to the proportion of adjudicators classifying the case as AKI. Subjects were classified as Kidney Disease: Improving Global Outcomes (KDIGO) AKI(+) when stage 2 or 3 AKI criteria were met. RESULTS: Concordance between adjudicators and between adjudicators and KDIGO criteria were lower for AKI than non-AKI subjects [78.9 versus 97.3% (P < 0.001) and 91.5 versus 97.9% (P = 0.01)]. Subjects who were AKI 3/3 or 2/3 but KDIGO AKI(-) had higher median [TIMP-2]•[IGFBP7] compared with those who were AKI-1/3 or 0/3 but KDIGO AKI(+) {2.78 [interquartile range (IQR) 2.33-3.56] versus 0.52 [IQR 0.26-1.64]; P = 0.008}. [TIMP-2]•[IGFBP7] levels were highest in patients with AKI 3/3 and lowest in AKI 0/3, whereas AKI 2/3 and 1/3 exhibited intermediate values. CONCLUSIONS: In this analysis, urine [TIMP-2]•[IGFBP7] levels correlated to clinically adjudicated AKI better than to KDIGO criteria. Furthermore, in difficult cases where adjudicators overruled KDIGO criteria, the biomarker test discriminated well. This study highlights the importance of clinical adjudication of AKI for biomarker studies and lends further support for the value of urine [TIMP-2]•[IGFBP7].

Relationship between expression of IGFBP7 and clinicopathological variables in gastric cancer.

AIMS: Insulin-like growth factor binding protein 7 (IGFBP7) is reported to have tumour suppressor function through an IGF-dependent pathway in various malignant tumours. However, the expression of IGFBP7 in adenocarcinoma and its relationship with tumour progression and survival differs among studies. Our aims were to investigate the relationship between the expression of IGFBP7 and clinicopathological variables and outcomes of patients with gastric cancer. METHODS: Tumour samples were obtained from 219 patients with gastric cancer who underwent gastrectomy. The expression of IGFBP7 protein was examined by immunohistochemical staining. IGFBP7 mRNA levels were analysed using real-time quantitative reverse-transcriptase PCR in 24 of the gastric cancer tumours and in adjacent non-tumour tissues. Correlation of IGFBP7 expression with clinicopathological features was analysed. RESULTS: The protein expression of IGFBP7 was positively correlated with depth of invasion, lymph node metastasis, distant metastasis or recurrence and pathological stage. High expression of IGFBP7 protein was associated with a significantly worse disease-specific survival (p<0.001) and was an independent prognostic factor in multivariable analysis (HR, 4.8; 95% CI 2.1 to 10.6; p<0.001). The IGFBP7 mRNA level was significantly higher in advanced gastric cancer than in early gastric cancer, in tumours with lymph node metastasis than in tumours without lymph node metastasis, and in tumours with distant metastasis or recurrence than in tumours without distant metastasis or recurrence. CONCLUSIONS: Overexpression of IGFBP7 was associated with tumour progression and poor survival in gastric cancer. IGFBP7 may play a role in tumour progression in gastric cancer.

The influence of nutrition on the insulin-like growth factor system and the concentrations of growth hormone, glucose, insulin, gonadotropins and progesterone in ovarian follicular fluid and plasma from adult female horses (Equus caballus).

BACKGROUND: Feed intake affects the GH-IGF system and may be a key factor in determining the ovarian follicular growth rate. In fat mares, the plasma IGF-1 concentration is high with low GH and a quick follicular growth rate, in contrast to values observed in thin mares. Nothing is known regarding the long-term effects of differential feed intake on the IGF system. The objective of this experiment was to quantify IGFs, IGFBPs, GH, glucose, insulin, gonadotropin and progesterone (P4) in blood and in preovulatory follicular fluid (FF) in relation to feeding levels in mares. METHODS: Three years prior to the experiment, Welsh Pony mares were assigned to a restricted diet group (R, n = 10) or a well-fed group (WF, n = 9). All mares were in good health and exhibited differences in body weight and subcutaneous fat thickness. Follicular development was scanned daily and plasma was also collected daily. Preovulatory FF was collected by ultrasound-guided follicular aspiration. Hormone levels were assayed in FF and plasma with a validated RIA. RESULTS: According to scans, the total number of follicles in group R was 53% lower than group WF. Insulin and IGF-1 concentrations were higher in WF than in R mares. GH and IGF-2 concentrations were lower in plasma from WF mares than from R mares, but the difference was not significant in FF. The IGFBP-2/IGFBP-3 ratio in FF was not affected by feeding but was dramatically increased in R mare plasma. No difference in gonadotropin concentration was found with the exception of FSH, which was higher in the plasma of R mares. On the day of puncture, P4 concentrations were not affected by feeding but were higher in preovulatory FF than in plasma. CONCLUSIONS: The bioavailability of IGF-1 or IGF-2, represented by the IGFBP2/IGFBP3 ratio, is modified by feed intake in plasma but not in FF. These differences partially explain the variability in follicular growth observed between well-fed mares and mares on restricted diets.

Differences in IGF axis-related proteins in amniotic fluid of trisomy 21 and trisomy 18 using a multiple reaction monitoring approach.

OBJECTIVE: Trisomy 21 and trisomy 18 are the two most common chromosomal anomalies in live births. To find new biomarkers for aneuploidies and pathogenesis of fetal malformations, we measured insulin-like growth factor (IGF) axis-related proteins in amniotic fluid (AF) of pregnant women carrying trisomies 21 or 18 affected fetuses using multiple reaction monitoring (MRM) approach. METHOD: Eighty-five AF samples from pregnant women carrying either trisomy 21, trisomy 18, or normal fetuses were collected. IGF axis-related proteins in AF after serial treatments were quantitated with MRM method. The differential protein levels were also confirmed by western blot in AF without any treatment. RESULTS: The IGF type I receptor and pregnancy-associated plasma protein-A in AF of trisomy 21 (1.35 ± 0.32 and 13.36 ± 3.64 µg/mg protein) and trisomy 18 (1.39 ± 0.40 and 12.80 ± 1.84 µg/mg protein) were decreased versus normal controls (2.16 ± 0.59 and 23.77 ± 6.18 µg/mg protein). IGF binding protein 5 was reduced in trisomy 18 (1.47 ± 0.33 vs 2.36 ± 0.77 µg/mg protein). These alterations were confirmed by western blot. The other proteins showed no significant difference between the three groups. CONCLUSION: Our data suggested that MRM can provide a powerful platform for the identification of biomarkers in AF that have crucial developmental effects in the aneuploid fetus.

Changes in cerebrospinal fluid and blood plasma levels of IGF-II and its binding proteins in Alzheimer's disease: an observational study.

BACKGROUND: The Insulin-like Growth Factor (IGF)-related system is implicated in neuroregeneration and cell repair, as well as regulating lifespan. IGF-II, one component of this system, has also been found to affect memory functions in a rat model. In this study we explored changes in the IGF-related system in patients with Alzheimer's disease (AD), including changes in IGF-II levels. METHODS: We measured blood plasma and cerebrospinal fluid (CSF) levels of IGF-I, IGF-II, IGFBP-2 and IGFBP-3 in 72 healthy controls and 92 patients with AD. RESULTS: We found significantly lower blood plasma levels of IGF-II and IGFBP-3 in patients with AD, compared with controls. The levels of IGF-II and IGFBP-2 were significantly elevated in the CSF from patients with AD. We also found correlations between established CSF biomarkers for AD (tau and P-tau) and components of the IGF system. CONCLUSIONS: CSF and blood plasma levels of IGF-II and some of its binding proteins are changed in patients with AD. Further investigation into this area may unravel important clues to the nature of this disease.