Netrin-1 and Semaphorin 3A Predict the Development of Acute Kidney Injury in Liver Transplant Patients

Acute kidney injury (AKI) is a serious complication after liver transplantation. Currently there are no validated biomarkers available for early diagnosis of AKI. The current study was carried out to determine the usefulness of the recently identified biomarkers netrin-1 and semaphorin 3A in predicting AKI in liver transplant patients. A total of 63 patients’ samples were collected and analyzed. AKI was detected at 48 hours after liver transplantation using serum creatinine as a marker. In contrast, urine netrin-1 (897.8±112.4 pg/mg creatinine), semaphorin 3A (847.9±93.3 pg/mg creatinine) and NGAL (2172.2±378.1 ng/mg creatinine) levels were increased significantly and peaked at 2 hours after liver transplantation but were no longer significantly elevated at 6 hours after transplantation. The predictive power of netrin-1, as demonstrated by the area under the receiver-operating characteristic curve for diagnosis of AKI at 2, 6, and 24 hours after liver transplantation was 0.66, 0.57 and 0.59, respectively. The area under the curve for diagnosis of AKI was 0.63 and 0.65 for semaphorin 3A and NGAL at 2 hr respectively. Combined analysis of two or more biomarkers for simultaneous occurrence in urine did not improve the AUC for the prediction of AKI whereas the AUC was improved significantly (0.732) only when at least 1 of the 3 biomarkers in urine was positive for predicting AKI. Adjusting for BMI, all three biomarkers at 2 hours remained independent predictors of AKI with an odds ratio of 1.003 (95% confidence interval: 1.000 to 1.006; P = 0.0364). These studies demonstrate that semaphorin 3A and netrin-1 can be useful early diagnostic biomarkers of AKI after liver transplantation.     

Comparison of Plasma and Urine Biomarker Performance in Acute Kidney Injury

Background

New renal biomarkers measured in urine promise to increase specificity for risk stratification and early diagnosis of acute kidney injury (AKI) but concomitantly may be altered by urine concentration effects and chronic renal insufficiency. This study therefore directly compared the performance of AKI biomarkers in urine and plasma.

Methods

This single-center, prospective cohort study included 110 unselected adults undergoing cardiac surgery with cardiopulmonary bypass between 2009 and 2010. Plasma and/or urine concentrations of creatinine, cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), liver fatty acid-binding protein (L-FABP), kidney injury molecule 1 (KIM1), and albumin as well as 15 additional biomarkers in plasma and urine were measured during the perioperative period. The primary outcome was AKI defined by AKIN serum creatinine criteria within 72 hours after surgery.

Results

Biomarkers in plasma showed markedly better discriminative performance for preoperative risk stratification and early postoperative (within 24h after surgery) detection of AKI than urine biomarkers. Discriminative power of urine biomarkers improved when concentrations were normalized to urinary creatinine, but urine biomarkers had still lower AUC values than plasma biomarkers. Best diagnostic performance 4h after surgery had plasma NGAL (AUC 0.83), cystatin C (0.76), MIG (0.74), and L-FAPB (0.73). Combinations of multiple biomarkers did not improve their diagnostic power. Preoperative clinical scoring systems (EuroSCORE and Cleveland Clinic Foundation Score) predicted the risk for AKI (AUC 0.76 and 0.71) and were not inferior to biomarkers. Preexisting chronic kidney disease limited the diagnostic performance of both plasma and urine biomarkers.

Conclusions

In our cohort plasma biomarkers had higher discriminative power for risk stratification and early diagnosis of AKI than urine biomarkers. For preoperative risk stratification of AKI clinical models showed similar discriminative performance to biomarkers. The discriminative performance of both plasma and urine biomarkers was reduced by preexisting chronic kidney disease.     

Serum and urinary biomarkers for early detection of acute kidney injury following Hypnale spp. envenoming

BackgroundHump-nosed pit viper (HNV; Hypnale spp.) bites account for most venomous snakebites in Sri Lanka. Acute kidney injury (AKI) is the most serious systemic manifestation (1–10%) following HNV envenoming. We aimed to identify the value of functional and injury biomarkers in predicting the development of AKI early following HNV bites.MethodsWe conducted a prospective cohort study of patients with confirmed HNV envenoming presenting to two large tertiary care hospitals in Sri Lanka. Demographics, bite details, clinical effects, complications and treatment data were collected prospectively. Blood and urine samples were collected from patients for coagulation and renal biomarker assays on admission, at 0-4h, 4-8h, 8-16h and 16-24h post-bite and daily until discharge. Follow-up samples were obtained 1 and 3 months post-discharge. Creatinine (sCr) and Cystatin C (sCysC) were measured in serum and kidney injury molecule-1 (uKIM-1), clusterin (uClu), albumin (uAlb), β2-microglobulin (uβ2M), cystatin C (uCysC), neutrophil gelatinase associated lipocalin (uNGAL), osteopontin (uOPN) and trefoil factor-3 (uTFF-3) were measured in urine. Definite HNV bites were based on serum venom specific enzyme immunoassay. Kidney Disease: Improving Global Outcomes (KDIGO) criteria were used to stage AKI. Two patients had chronic kidney disease at 3 month follow-up, both with pre-existing abnormal sCr, and one developed AKI following HNV envenoming.ResultsThere were 52 patients with confirmed HNV envenoming; median age 48y (Interquartile range [IQR]:40-59y) and 29 (56%) were male. Median time to admission was 1.87h (IQR:1–2.75h). Twelve patients (23%) developed AKI (AKI stage 1 = 7, AKI stage 2 = 1, AKI stage 3 = 4). Levels of five novel biomarkers, the functional marker serum Cystatin C and the damage markers urinary NGAL, cystatin C, β2-microglobulin and clusterin, were elevated in patients who developed moderate/severe acute kidney injury. sCysC performed the best at 0–4 h post-bite in predicting moderate to severe AKI (AUC-ROC 0.95;95%CI:0.85–1.0) and no biomarker performed better than sCr at later time points.ConclusionssCysC appears to be a better marker than sCr for early prediction of moderate to severe AKI following HNV envenoming.     

Urinary L-FABP and its combination with urinary NGAL in early diagnosis of acute kidney injury after cardiac surgery in adult patients

Background/Aim: The early detection of acute kidney injury (AKI) may be become possible by several promising early biomarkers which may facilitate the early detection, differentiation and prognosis prediction of AKI. In this study, we investigated the value of urinary liver-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL) and their combination in predicting the occurrence and the severity of AKI following cardiac surgery.

Methods: We prospectively followed 109 patients undergoing open heart surgery and identified 26 that developed AKI, defined as an increase in serum creatinine of ≥0.3?mg/dl or ≥150% of baseline creatinine. Serum creatinine (SCr), urinary L-FABP, and NGAL corrected by urine creatinine were tested pre-operation, at 0 hour and 2 hours post-operation. Each marker was assessed at each time point between patients with and without AKI. Receiver operating characteristic (ROC) curves and area under curves (AUC) were used to evaluate the diagnostic accuracy of urinary L-FABP, NGAL and their combination for predicting AKI.

Results: Patients were aged 63.0?±?11.3 years, 66.1% were male and baseline SCr was 70.5?±?19.1 umol/L. Of 109 patients, 26(23.9%) developed AKI (AKIN stage I, II and III were 46.2%, 34.6% and 19.2% separately). The levels of urinary L-FABP and NGAL were significantly higher in AKI patients than non-AKI patients at 0 hour and 2 hours postoperative. AUCs for L-FABP was 0.844 (sensitivity (ST) 0.846, specificity (SP) 0.819, cut-off (CO) 2226.50 μg/g Ucr) at 0 hours and 0.832 at 2 hours (ST 0.808, SP 0.747, CO 673.09 μg/g Ucr) while 0.866 for NGAL at 0 hours (ST 0.769, SP 0.819, CO 131.12 μg/g Ucr) and 0.871 at 2 hours (ST 0.808, SP 0.831, CO 33.73 μg/g Ucr) to predict AKI occurrence. Using a combination of L-FABP and NGAL analyzed at the same timepoint as above, we were able to obtain an AUC of 0.911–0.927, p < 0.001. Similar AUCs of 0.81–0.87 were found to predict AKI stage II–III.

Conclusions: Urinary L-FABP and NGAL increased at an early stage after cardiac surgery. The combination of the two biomarkers enhanced the accuracy of the early detection of postoperative AKI after cardiac surgery before a rise in SCr.     

Analysis of a Urinary Biomarker Panel for Clinical Outcomes Assessment in Cirrhosis

Background

Biomarkers are potentially useful in assessment of outcomes in patients with cirrhosis, but information is very limited. Given the large number of biomarkers, adequate choice of which biomarker(s) to investigate first is important.

Aim

Analysis of potential usefulness of a panel of urinary biomarkers in outcome assessment in cirrhosis.

Patients and Methods

Fifty-five patients with acute decompensation of cirrhosis were studied: 39 had Acute Kidney Injury (AKI) (Prerenal 12, type-1 HRS (hepatorenal syndrome) 15 and Acute Tubular Necrosis (ATN) 12) and 16 acute decompensation without AKI. Thirty-four patients had Acute-on-chronic liver failure (ACLF). A panel of 12 urinary biomarkers was assessed, using a multiplex assay, for their relationship with ATN, ACLF and mortality.

Results

Biomarker with best accuracy for ATN diagnosis was NGAL (neutrophil-gelatinase associated lipocalin): 36 [26-125], 104 [58-208] and 1807 [494-3,716] μg/g creatinine in Prerenal-AKI, type-1 HRS and ATN, respectively; p<0.0001 (AUROC 0.957). Other attractive biomarkers for ATN diagnosis were IL-18, albumin, trefoil-factor-3 (TFF-3) and glutathione-S-transferase-π (GST-π) Biomarkers with less accuracy for ATN AUCROC<0.8 were β2-microglobulin, calbindin, cystatin-C, clusterin and KIM-1 (kidney injury molecule-1). For ACLF, the biomarker with the best accuracy was NGAL (ACLF vs. No-ACLF: 165 [67-676] and 32 [19-40] μg/g creatinine; respectively; p<0.0001; AUROC 0.878). Interestingly, other biomarkers with high accuracy for ACLF were osteopontin, albumin, and TFF-3. Biomarkers with best accuracy for prognosis were those associated with ACLF.

Conclusions

A number of biomarkers appear promising for differential diagnosis between ATN and other types of AKI. The most interesting biomarkers for ACLF and prognosis are NGAL, osteopontin, albumin, and TFF-3. These results support the role of major inflammatory reaction in the pathogenesis of ACLF.     

Combined Biomarker Analysis for Risk of Acute Kidney Injury in Patients with ST-Segment Elevation Myocardial Infarction

Background

Acute kidney injury (AKI) complicating ST-segment elevation myocardial infarction (STEMI) increases subsequent morbidity and mortality. We combined the biomarkers of heart failure (HF; B-type natriuretic peptide [BNP] and soluble ST2 [sST2]) and renal injury (NGAL [neutrophil gelatinase-associated lipocalin] and cystatin C) in predicting the development of AKI in patients with STEMI undergoing primary percutaneous coronary intervention (PCI).

Methods and Results

From March 2010 to September 2013, 189 STEMI patients were sequentially enrolled and serum samples were collected at presentation for BNP, sST2, NGAL and cystatin C analysis. 37 patients (19.6%) developed AKI of varying severity within 48 hours of presentation. Univariate analysis showed age, Killip class ≥2, hypertension, white blood cell counts, hemoglobin, estimated glomerular filtration rate, blood urea nitrogen, creatinine, and all the four biomarkers were predictive of AKI. Serum levels of the biomarkers were correlated with risk of AKI and the Acute Kidney Injury Network (AKIN) stage and all significantly discriminated AKI (area under the receiver operating characteristic [ROC] curve: BNP: 0.86, sST2: 0.74, NGAL: 0.75, cystatin C: 0.73; all P < 0.05). Elevation of ≥2 of the biomarkers higher than the cutoff values derived from the ROC analysis improved AKI risk stratification, regardless of the creatine level (creatinine < 1.24 mg/dL: odds ratio [OR] 11.25, 95% confidence interval [CI] 1.63-77.92, P = 0.014; creatinine ≥ 1.24: OR 15.0, 95% CI 1.23-183.6, P = 0.034).

Conclusions

In this study of STEMI patients undergoing primary PCI, the biomarkers of heart failure (BNP and sST2) and renal injury (NGAL and cystatin C) at presentation were predictive of AKI. High serum levels of the biomarkers were associated with an elevated risk and more advanced stage of AKI. Regardless of the creatinine level, elevation of ≥2 of the biomarkers higher than the cutoff values indicated a further rise in AKI risk. Combined biomarker approach may assist in risk stratification of AKI in patients with STEMI.     

Klotho and S100A8/A9 as Discriminative Markers between Pre-Renal and Intrinsic Acute Kidney Injury

Early detection and accurate differentiation of the cause of AKI may improve the prognosis of the patient. However, to date, there are few reliable biomarkers that can discriminate between pre-renal and intrinsic AKI. In this study, we determined whether AKI is associated with altered serum and urinary levels of Klotho, S100A8/A9 (an endogenous ligand of toll-like receptor 4), and neutrophil gelatinase-associated lipocalin (NGAL), which may allow differentiation between pre-renal and intrinsic AKI. A volume-depleted pre-renal AKI model was induced in male Sprague Dawley rats fed a low-salt diet (0.03%) without water 96 h before two intraperitoneal (IP) injections of furosemide (20 mg/kg) at a 24 h interval. In contrast, in the cisplatin-induced intrinsic AKI model, animals were given a single IP injection of cisplatin (5 mg/kg). All of the animals were euthanized 72 h after the first IP injection. Serum and urinary levels of Klotho, S100A8/A9, and NGAL were measured using an enzyme-linked immunosorbent assay. We also performed a proof-of-concept cross-sectional study to measure serum and urinary biomarkers in 61 hospitalized patients with established AKI. Compared to the intrinsic AKI group, the pre-renal AKI group showed a marked depression in urinary Klotho levels (13.21±17.32 vs. 72.97±17.96 pg/mL; P = 0.002). In addition, the intrinsic AKI group showed marked elevation of S100A8/A9 levels compared to the pre-renal AKI group (2629.97±598.05 ng/mL vs. 685.09±111.65 ng/mL; P = 0.002 in serum; 3361.11±250.86 ng/mL vs. 741.72±101.96 ng/mL; P = 0.003 in urine). There was no difference in serum and urinary NGAL levels between the pre-renal and intrinsic AKI groups. The proof-of-concept study with the hospitalized AKI patients also demonstrated decreased urinary Klotho in pre-renal AKI patients and increased urinary S100A8/A9 concentrations in intrinsic AKI patients. The attenuation of urinary Klotho and increase in urinary S100A8/A9 may allow differentiation between pre-renal and intrinsic AKI.     

Update on biomarkers of acute kidney injury: moving closer to clinical impact?

Acute kidney injury (AKI) represents a common disorder in hospitalized patients, and its incidence is rising at an alarming rate. Despite significant improvements in critical care and renal replacement therapies (RRT), the outcome of critically ill patients with AKI necessitating RRT remains unacceptably dismal. In current clinical practice, the diagnosis and severity classification of AKI is based on a rise in serum creatinine levels, which may occur 2-3 days after the initiating renal insult and delay potentially effective therapies that are limited to the early stage. The emergence of numerous renal tubular damage-specific biomarkers offers an opportunity to diagnose AKI at an early timepoint, to facilitate differential diagnosis of structural and functional AKI, and to predict the outcome of established AKI. The purposes of this review are to summarize and to discuss the performance of these novel AKI biomarkers in various clinical settings. The most promising AKI biomarkers include plasma and urinary neutrophil gelatinase-associated lipocalin (NGAL), urinary interleukin (IL)-18, urinary liver-type fatty acid binding protein (L-FABP), urinary cystatin C, and urinary kidney injury molecule (KIM)-1. However, enthusiasm about their usefulness in the emergency department seems unwarranted at present. There is little doubt that urinary biomarkers of nephron damage may enable prospective diagnostic and prognostic stratification in the emergency department. However, comparison of the areas under the receiver-operating characteristic curves of these biomarkers with clinical and/or routine biochemical outcome parameters reveals that none of these biomarkers has a clear advantage beyond the traditional approach in clinical decision making in patients with AKI. The performance of various biomarkers for predicting AKI in patients with sepsis or with acute-on-chronic kidney disease is poor. The inability of biomarkers to improve classification of 'unclassifiable' (structural or functional) AKI, in which accurate differential diagnosis of pre-renal versus intrinsic renal AKI has the most value, illustrates another problem. Future research is necessary to clarify whether serial measurements of a specific biomarker or the use of a panel of biomarkers may be more useful in critically ill patients at risk of AKI. Whether or not the use of AKI biomarkers revolutionizes critical care medicine by early diagnosis of severe AKI and individualizes the management of AKI patients remains to be shown. Currently, the place of biomarkers in this decision-making process is still uncertain. Indiscriminate use of various biomarkers may distract clinicians from adequate clinical evaluation, may result in worse instead of better patient outcomes, and may waste money. Future large randomized studies are necessary to demonstrate the association between biomarker levels and clinical outcomes, such as dialysis, clinical events, or death. It needs to be shown whether assignment to earlier treatment for AKI on the basis of generally accepted biomarker cut-off levels results in a reduction in mortality and an improvement in recovery of renal function.     

先天性心脏病患儿术后急性肾损伤的影响因素及尿NGAL、KIM-1的诊断价值分析

摘要 目的：探讨影响先天性心脏病患儿术后急性肾损伤（AKI）的影响因素及尿中性粒细胞明胶酶相关脂质运载蛋白（NGAL）、肾损伤分子1（KIM-1）的诊断价值。方法：选择2018年1月至2019年12月我院心胸外科收治的60例先天性心脏病术后并发AKI患儿（AKI组）和同期收治的172例先天性心脏病术后未发生AKI患儿（NAKI组）作为研究对象。收集患儿临床基线资料,检测尿NGAL、KIM-1水平,采用Logistic回归分析先天性心脏病患儿术后发生AKI的影响因素,受试者工作特征曲线（ROC）分析尿NGAL、KIM-1诊断先天性心脏病患儿术后发生AKI的价值。结果：AKI组年龄、体重低于NAKI组（P＜0.05）,手术时间、心肺转流（CPB）时间、主动脉阻断（ACT）时间、机械通气时间、重症监护室（ICU）住院时间长于NAKI组（P＜0.05）,术后平均动脉压（MAP）、尿素氮（BUN）、血肌酐（Scr）、NGAL、KIM-1高于NAKI组（P＜0.05）。Logistic回归分析结果显示低龄、低体重、CPB时间长、高NGAL、KIM-1水平是先天性心脏病患儿术后发生AKI的危险因素（P＜0.05）。ROC分析显示尿NGAL、KIM-1诊断先天性心脏病患儿术后发生AKI的灵敏度分别为81.67%,83.33%,特异度分别为84.30%,87.79%。结论：低龄、低体重、CPB时间长、高NGAL、KIM-1水平是先天性心脏病患儿术后发生AKI的危险因素,尿NGAL、KIM-1诊断先天性心脏病术后AKI具有较高价值。     

Acute kidney injury biomarkers for patients in a coronary care unit: a prospective cohort study

Background

Renal dysfunction is an established predictor of all-cause mortality in intensive care units. This study analyzed the outcomes of coronary care unit (CCU) patients and evaluated several biomarkers of acute kidney injury (AKI), including neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18) and cystatin C (CysC) on the first day of CCU admission.

Methodology/Principal Findings

Serum and urinary samples collected from 150 patients in the coronary care unit of a tertiary care university hospital between September 2009 and August 2010 were tested for NGAL, IL-18 and CysC. Prospective demographic, clinical and laboratory data were evaluated as predictors of survival in this patient group. The most common cause of CCU admission was acute myocardial infarction (80%). According to Acute Kidney Injury Network criteria, 28.7% (43/150) of CCU patients had AKI of varying severity. Cumulative survival rates at 6-month follow-up following hospital discharge differed significantly (p<0.05) between patients with AKI versus those without AKI. For predicting AKI, serum CysC displayed an excellent areas under the receiver operating characteristic curve (AUROC) (0.895±0.031, p<0.001). The overall 180-day survival rate was 88.7% (133/150). Multiple Cox logistic regression hazard analysis revealed that urinary NGAL, serum IL-18, Acute Physiology, Age and Chronic Health Evaluation II (APACHE II) and sodium on CCU admission day one were independent risk factors for 6-month mortality. In terms of 6-month mortality, urinary NGAL had the best discriminatory power, the best Youden index, and the highest overall correctness of prediction.

Conclusions

Our data showed that serum CysC has the best discriminative power for predicting AKI in CCU patients. However, urinary NGAL and serum IL-18 are associated with short-term mortality in these critically ill patients.     

Levels of Protein C and Soluble Thrombomodulin in Critically Ill Patients with Acute Kidney Injury: A Multicenter Prospective Observational Study

Endothelial dysfunction contributes to the development of acute kidney injury (AKI) in animal models of ischemia reperfusion injury and sepsis. There are limited data on markers of endothelial dysfunction in human AKI. We hypothesized that Protein C (PC) and soluble thrombomodulin (sTM) levels could predict AKI. We conducted a multicenter prospective study in 80 patients to assess the relationship of PC and sTM levels to AKI, defined by the AKIN creatinine (AKI Scr) and urine output criteria (AKI UO). We measured marker levels for up to 10 days from intensive care unit admission. We used area under the curve (AUC) and time-dependent multivariable Cox proportional hazard model to predict AKI and logistic regression to predict mortality/non-renal recovery. Protein C and sTM were not different in patients with AKI UO only versus no AKI. On intensive care unit admission, as PC levels are usually lower with AKI Scr, the AUC to predict the absence of AKI was 0.63 (95%CI 0.44-0.78). The AUC using log10 sTM levels to predict AKI was 0.77 (95%CI 0.62-0.89), which predicted AKI Scr better than serum and urine neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, urine kidney injury molecule-1 and liver-fatty acid-binding protein. In multivariable models, PC and urine NGAL levels independently predicted AKI (p=0.04 and 0.02) and PC levels independently predicted mortality/non-renal recovery (p=0.04). In our study, PC and sTM levels can predict AKI Scr but are not modified during AKI UO alone. PC levels could independently predict mortality/non-renal recovery. Additional larger studies are needed to define the relationship between markers of endothelial dysfunction and AKI.     

Urinary neutrophil gelatinase-associated lipocalin and L-type fatty acid binding protein as diagnostic markers of early acute kidney injury after liver transplantation

Objective: We examined the value of two potential novel urinary biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) and L-type fatty acid binding protein (L-FABP), in diagnosing acute kidney injury (AKI) in liver transplant recipients.

Methods: NGAL and L-FABP in urinary sample from Twenty-five patients before surgery and at 2, 4, 6, 12, 24, 48, 72 and 120 h after the anhepatic phase were tested. Standard statistics were used along with receiver-operating characteristic (ROC) analysis to evaluate the diagnostic value of selected markers.

Results: Urinary NGAL was only slightly elevated at 2 h in the non-AKI group while rose and stayed high from 2–6 h in the AKI group. However, urinary L-FABP rose transiently in both groups 2–120 h following surgery. The level of urinary NGAL presented differences at 2–6 h (p < 0.05) and urinary L-FABP at 4 h (p < 0.05) between AKI and non-AKI groups. ROC analysis showed that area under the curves (AUCs) of NGAL were 0.766, 0.773, and 0.773 at 2, 4 and 6 h respectively while 0.760 of L-FABP at 4 h.

Conclusion: Urinary NGAL rather than L-FABP appeared to be a sensitive and specific marker of AKI in liver transplant recipients.     

Raised Plasma Robo4 and Cardiac Surgery-Associated Acute Kidney Injury

Objective

Endothelial dysfunction associated with systemic inflammation can contribute to organ injury/failure following cardiac surgery requiring cardiopulmonary bypass (CPB). Roundabout protein 4 (Robo4), an endothelial-expressed transmembrane receptor and regulator of cell activation, is an important inhibitor of endothelial hyper-permeability. We investigated the hypothesis that plasma levels of Robo4 are indicative of organ injury, in particular acute kidney injury (AKI), after cardiac surgery.

Methods

Patients (n = 32) undergoing elective cardiac surgery with CPB were enrolled, prospectively. Plasma Robo4 concentrations were measured pre-, 2 and 24 h post-operatively, using a commercially available ELISA. Plasma and endothelial markers of inflammation [interleukin (IL) -6, -8, -10: von Willibrand factor (vWF) and angiopoeitin-2 (Ang-2)] and the AKI marker, neutrophil gelatinase-associated lipocalin (NGAL), were also measured by ELISA.

Results

Plasma Robo4 increased significantly (p<0.001) from pre-operative levels of 2515±904 pg/ml to 4473±1915 pg/ml, 2 h after surgery; and returned to basal levels (2682±979 pg/ml) by 24 h. Plasma cytokines, vWF and NGAL also increased 2 h post-operatively and remained elevated at 24 h. Ang-2 increased 24 h post-operatively, only. There was a positive, significant correlation (r = 0.385, p = 0.0298) between Robo-4 and IL-10, but not other cytokines, 2 h post-operatively. Whilst raised Robo4 did not correlate with indices of lung dysfunction or other biomarkers of endothelial activation; there was a positive, significant correlation between raised (2 h) plasma NGAL and Robo4 (r = 0.4322, p = 0.0135). When patients were classed as AKI or non-AKI either using NGAL cut-off of 150 ng/ml, or the AKI Network (AKIN) clinical classification; plasma Robo4 was significantly higher (p = 0.0073 and 0.003, respectively) in AKI vs. non-AKI patients (NGAL cut-off: 5350±2191 ng/ml, n = 16 vs. 3595±1068 pg/ml, n = 16; AKIN: 6546 pg/ml, IQR 5025–8079, n = 6; vs. 3727 pg/ml, IQR 1962–3727, n = 26) subjects.

Conclusion

Plasma Robo4 levels are increased, transiently, following cardiac surgery requiring CPB; and higher levels in patients with AKI suggest a link between endothelial dysregulation and onset of AKI.     

Comparative analysis of urinary biomarkers for early detection of acute kidney injury following cardiopulmonary bypass

The purpose of this study was to compare the performance of six candidate urinary biomarkers, kidney injury molecule (KIM)-1, N-acetyl-β-D-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL), interleukin (IL)-18, cystatin C and α-1 microglobulin, measured 2?h following cardiopulmonary bypass (CPB) for the early detection of acute kidney injury (AKI) in a prospective cohort of patients undergoing cardiac surgery. A total of 103 subjects were enrolled; AKI developed in 13%. Urinary KIM-1 achieved the highest area under-the-receiver-operator-characteristic curve (AUC 0.78, 95% confidence interval 0.64–0.91), followed by IL-18 and NAG. Only urinary KIM-1 remained independently associated with AKI after adjustment for a preoperative AKI prediction score (Cleveland Clinic Foundation score; p?=?0.02), or CPB perfusion time (p?=?0.006). In this small pilot cohort, KIM-1 performed best as an early biomarker for AKI. Larger studies are needed to explore further the role of biomarkers for early detection of AKI following cardiac surgery.     

Cystatin C,a novel urinary biomarker for sensitive detection of acute kidney injury during haemorrhagic fever with renal syndrome

To explore the value of cystatin C for evaluating acute kidney injury (AKI) in haemorrhagic fever with renal syndrome (HFRS), the concentrations of cystatin C in serum and urine samples from HFRS patients were determined. The serum and urinary cystatin C concentrations significantly increased in HFRS patients compared with normal controls (p?<?0.001). In the acute phase of HFRS, urinary cystatin C increased to higher levels than serum creatinine, especially in severe or critical cases in the oliguric stage. Furthermore, higher levels of urinary cystatin C in the acute phase positively correlated with increased severity of the subsequent kidney injury. In conclusion, urinary cystatin C is a more sensitive clinical marker for AKI in HFRS, which may enable us to initiate treatment measures as early as possible.     

Predictive Usefulness of Urinary Biomarkers for the Identification of Cyclosporine A-Induced Nephrotoxicity in a Rat Model

The main side effect of cyclosporine A (CsA), a widely used immunosuppressive drug, is nephrotoxicity. Early detection of CsA-induced acute nephrotoxicity is essential for stop or minimize kidney injury, and timely detection of chronic nephrotoxicity is critical for halting the drug and preventing irreversible kidney injury. This study aimed to identify urinary biomarkers for the detection of CsA-induced nephrotoxicity. We allocated salt-depleted rats to receive CsA or vehicle for 7, 14 or 21 days and evaluated renal function and hemodynamics, microalbuminuria, renal macrophage infiltration, tubulointerstitial fibrosis and renal tissue and urinary biomarkers for kidney injury. Kidney injury molecule-1 (KIM-1), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), fibronectin, neutrophil gelatinase-associated lipocalin (NGAL), TGF-β, osteopontin, and podocin were assessed in urine. TNF-α, IL-6, fibronectin, osteopontin, TGF-β, collagen IV, alpha smooth muscle actin (α -SMA) and vimentin were assessed in renal tissue. CsA caused early functional renal dysfunction and microalbuminuria, followed by macrophage infiltration and late tubulointerstitial fibrosis. Urinary TNF-α, KIM-1 and fibronectin increased in the early phase, and urinary TGF-β and osteopontin increased in the late phase of CsA nephrotoxicity. Urinary biomarkers correlated consistently with renal tissue cytokine expression. In conclusion, early increases in urinary KIM-1, TNF-α, and fibronectin and elevated microalbuminuria indicate acute CsA nephrotoxicity. Late increases in urinary osteopontin and TGF-β indicate chronic CsA nephrotoxicity. These urinary kidney injury biomarkers correlated well with the renal tissue expression of injury markers and with the temporal development of CsA nephrotoxicity.     

建立NGAL诊断阈值有利于临床判断和发现急性肾功能损伤

为探讨中性粒细胞相关载脂蛋白(neutrophil gelatinase-associated lipocalin, NGAL)检测在肝胆疾病患者继发急性肾功能损伤(acute kidney injury, AKI)中的诊断性能,本研究回顾性收集了476例肝胆疾病患者与225例健康受试者作为实验组,根据血清中性粒细胞相关载脂蛋白(NGAL)、血清肌酐(serum creatinine,s Cr)、尿素(Urea)、半胱氨酸蛋白酶抑制剂C (cystatin C, CysC)、估算肾小球滤过率(estimating glomerular filtration rate, eGFR)水平和尿量,分为急性肾功能损伤(AKI)组和高风险(high-risk, HR)组、低风险(low-risk,LR)组和对照(health control, HC)组,进而建立上述血清指标在急性肾功能损伤(AKI)诊断性能最大时的判断界值;随后,选取145例肝胆疾病患者作为验证组,以评估各观察指标对肝胆疾病继发急性肾功能损伤(AKI)的诊断性能。结果表明:本实验组中各亚组间所观察指标之血清水平均有统计学差异(p<0.05)。中性粒细胞相关载脂蛋白(NGAL)诊断性能最大时的判断界值为205.2μg/L。验证组患者各指标阳性检出率,在低风险(LR)亚组中中性粒细胞相关载脂蛋白(NGAL)均高于其它指标(p<0.05),但在高风险(HR)亚组中中性粒细胞相关载脂蛋白(NGAL)仅高于血清肌酐(sCr)(p<0.05),而与半胱氨酸蛋白酶抑制剂C (CysC)和估算肾小球滤过率(eGFR)无统计学差异(p>0.05);再经分层风险分析各指标预测高风险(HR)亚组患者急性肾功能损伤(AKI)发生的能力,中性粒细胞相关载脂蛋白(NGAL)的优势比(OR=21.0 (2.3, 192.8)),是半胱氨酸蛋白酶抑制剂C(CysC)或估算肾小球滤过率(eGFR)(OR (95%CI)=3.3 (0.7, 15.3))的6.4倍。本研究初步结论表明,肝胆疾病患者诊断急性肾功能损伤(AKI)时应考虑中性粒细胞相关载脂蛋白(NGAL)肝脏合成代谢的作用。因此实验室应建立适宜的中性粒细胞相关载脂蛋白(NGAL)诊断阈值以有利于临床准确判断及早期发现急性肾功能损伤(AKI)。     

Neutrophil Gelatinase Associated Lipocalin (NGAL) in Leptospirosis Acute Kidney Injury: A Multicenter Study in Thailand

AKI is one of the most serious complications of leptospirosis, an important zoonosis in the tropics. Recently, NGAL, one of the novel AKI biomarkers, is extensively studied in various specific settings such as sepsis, cardiac surgery, and radiocontrast nephropathy. In this multicenter study, we aimed to study the role of NGAL as an early marker and an outcome predictor of leptospirosis associated AKI. Patients who presented with clinical suspiciousness of leptospirosis were prospectively enrolled in 9 centers from August 2012 to November 2014. The first day of enrollment was the first day of clinical suspicious leptospirosis. Blood and urine samples were serially collected on the first three days and day 7 after enrollment. We used three standard techniques (microscopic agglutination test, direct culture, and PCR technique) to confirm the diagnosis of leptospirosis. KDIGO criteria were used for AKI diagnosis. Recovery was defined as alive and not requiring dialysis during hospitalization or maintaining maximum KDIGO stage at hospital discharge. Of the 221 recruited cases, 113 cases were leptospirosis confirmed cases. Thirty seven percent developed AKI. Median uNGAL and pNGAL levels in those developing AKI were significantly higher than in patients not developing AKI [253.8 (631.4) vs 24.1 (49.6) ng/ml, p < 0.001] and [1,030 (802.5) vs 192.0 (209.0) ng/ml, p < 0.001], respectively. uNGAL and pNGAL levels associated with AKI had AUC-ROC of 0.91, and 0.92, respectively. Both of urine NGAL and pNGAL level between AKI-recovery group and AKI-non recovery were comparable. From this multicenter study, uNGAL and pNGAL provided the promising result to be a marker for leptospirosis associated AKI. However, both of them did not show the potential role to be the predictor of renal recovery in this specific setting.     

Standardization of Diagnostic Biomarker Concentrations in Urine: The Hematuria Caveat

Sensitive and specific urinary biomarkers can improve patient outcomes in many diseases through informing early diagnosis. Unfortunately, to date, the accuracy and translation of diagnostic urinary biomarkers into clinical practice has been disappointing. We believe this may be due to inappropriate standardization of diagnostic urinary biomarkers. Our objective was therefore to characterize the effects of standardizing urinary levels of IL-6, IL-8, and VEGF using the commonly applied standards namely urinary creatinine, osmolarity and protein. First, we report results based on the biomarker levels measured in 120 hematuric patients, 80 with pathologically confirmed bladder cancer, 27 with confounding pathologies and 13 in whom no underlying cause for their hematuria was identified, designated “no diagnosis”. Protein levels were related to final diagnostic categories (p = 0.022, ANOVA). Osmolarity (mean = 529 mOsm; median = 528 mOsm) was normally distributed, while creatinine (mean = 10163 µmol/l, median = 9350 µmol/l) and protein (0.3297, 0.1155 mg/ml) distributions were not. When we compared AUROCs for IL-6, IL-8 and VEGF levels, we found that protein standardized levels consistently resulted in the lowest AUROCs. The latter suggests that protein standardization attenuates the “true” differences in biomarker levels across controls and bladder cancer samples. Second, in 72 hematuric patients; 48 bladder cancer and 24 controls, in whom urine samples had been collected on recruitment and at follow-up (median = 11 (1 to 20 months)), we demonstrate that protein levels were approximately 24% lower at follow-up (Bland Altman plots). There was an association between differences in individual biomarkers and differences in protein levels over time, particularly in control patients. Collectively, our findings identify caveats intrinsic to the common practice of protein standardization in biomarker discovery studies conducted on urine, particularly in patients with hematuria.     

NGAL、KIM-1和PCT在脓毒症AKI中的标志物作用

探讨NGAL与KIM-1联合检测和PCT在重症监护病房重症患者中急性肾损伤(AKI)发生中的作用。选取2018年1月至2019年6月我院101例重症患者,其中脓毒症AKI组61例,非AKI组40例,通过分析NGAL、KIM-1和PCT在2组患者中表达水平变化情况,结合与ACR指标对比分析,评价NGAL、KIM-1和PCT在脓毒症急性肾损伤早期诊断中的价值。结果显示,所有脓毒症AKI患者均检测出明显更高的尿NGAL生物标志物水平(67.32μg/g Cr)。尿KIM-1和尿NGAL水平升高与患者ACR升高均呈正相关(p<0.001),而在脓毒症AKI患者中PCT和ACR之间观察到显著的负相关(r_s=-0.102 5, p=0.307)。通过Kruskal-Wallis检验发现,NGAL和KIM-1值显示出与脓毒症严重程度具有显著统计学意义,且直接成比例的关系(p≤0.01)。进一步检查NGAL、KIM-1和PCT标志物与病情发展的相关性表明,PCT值似乎与临床结果没有很强的相关性。尿KIM-1联合NGAL在早期检测脓毒症AKI中具有较大的预测价值;PCT是有希望的脓毒症标志物之一,但不足以提供可靠诊断依据,在肾功能下降的患者中通过PCT进行脓毒症的临床诊断需要更加谨慎。