Urinary Biomarkers for Diagnosis and Prediction of Acute Kidney Allograft Rejection: A Systematic Review.

Noninvasive tools for diagnosis or prediction of acute kidney allograft rejection have been extensively investigated in recent years. Biochemical and molecular analyses of blood and urine provide a liquid biopsy that could offer new possibilities for rejection prevention, monitoring, and therefore, treatment. Nevertheless, these tools are not yet available for routine use in clinical practice. In this systematic review, MEDLINE was searched for articles assessing urinary biomarkers for diagnosis or prediction of kidney allograft acute rejection published in the last five years (from January 1, 2015 to May 31, 2020). This review follows the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Articles providing targeted or unbiased urine sample analysis for the diagnosis or prediction of both acute cellular and antibody-mediated kidney allograft rejection were included, analyzed, and graded for methodological quality with a particular focus on study design and diagnostic test accuracy measures. Urinary C-X-C motif chemokine ligands were the most promising and frequently studied biomarkers. The combination of precise diagnostic reference in training sets with accurate validation in real-life cohorts provided the most relevant results and exciting groundwork for future studies.

Twenty-four-hour normothermic perfusion of discarded human kidneys with urine recirculation.

Transportable normothermic kidney perfusion for 24 hours or longer could enable viability assessment of marginal grafts, increased organ use, and improved transplant logistics. Eleven clinically declined kidneys were perfused normothermically, with 6 being from donors after brain death (median cold ischemia time 33 ± 36.9 hours) and 5 being from donors after circulatory death (36.2 ± 38.3 hours). Three kidneys were perfused using Ringer's lactate to replace excreted urine volume, and 8 kidneys were perfused using urine recirculation to maintain perfusate volume without fluid replenishment. In all cases, normothermic perfusion either maintained or slightly improved the histopathologically assessed tubular condition, and there was effective urine production in kidneys from both donors after brain death and donors after circulatory death (2367 ± 1798 mL vs 744.4 ± 198.4 mL, respectively; P = .44). Biomarkers, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 were successfully detected and quantified in the perfusate. All kidneys with urine recirculation were readily perfused for 24 hours (n = 8) and exhibited physiological perfusate sodium levels (140.7 ± 1.2 mmol/L), while kidneys without urine recirculation (n = 3) achieved a reduced normothermic perfusion time of 7.7 ± 1.5 hours and significantly higher perfusate sodium levels (159.6 ± 4.63 mmol/:, P < .01). Normothermic machine perfusion of human kidneys for 24 hours appears to be feasible, and urine recirculation was found to facilitate the maintenance of perfusate volume and homeostasis.

Development of a Clinical Decision Support System for Living Kidney Donor Assessment Based on National Guidelines.

BACKGROUND: Live donor nephrectomy is an operation that places the donor at risk of complications without the possibility of medical benefit. Rigorous donor selection and assessment is therefore essential to ensure minimization of risk and for this reason robust national guidelines exist. Previous studies have demonstrated poor adherence to donor guidelines. METHODS: We developed a clinical decision support system (CDSS), based on national living donor guidelines, to facilitate the identification of contraindications, additional investigations, special considerations, and the decision as to nephrectomy side in potential living donors. The CDSS was then tested with patient data from 45 potential kidney donors. RESULTS: The CDSS comprises 17 core tasks completed by either patient or nurse, and 17 optional tasks that are triggered by certain patient demographics or conditions. Decision rules were able to identify contraindications, additional investigations, special considerations, and predicted operation side in our patient cohort. Seventeen of 45 patients went on to donate a kidney, of whom 7 had major contraindications defined in the national guidelines, many of which were not identified by the clinical team. Only 43% of additional investigations recommended by national guidelines were completed, with the most frequently missed investigations being oral glucose tolerance testing and routine cancer screening. CONCLUSIONS: We have demonstrated the feasibility of turning a complex set of national guidelines into an easy-to-use machine-readable CDSS. Comparison with real-world decisions suggests that use of this CDSS may improve compliance with guidelines and informed consent tailored to individual patient risks.

A Double Blind Randomized Clinical Trial of Remote Ischemic Conditioning in Live Donor Renal Transplantation.

Ischemic conditioning involves the delivery of short cycles of reversible ischemic injury in order to induce protection against subsequent more prolonged ischemia. This randomized controlled trial was designed to determine the safety and efficacy of remote ischemic conditioning (RC) in live donor kidney transplantation.This prospective randomized clinical trial, 80 patients undergoing live donor kidney transplantation were randomly assigned in a 1:1 ratio to either RC or to a control group. RC consisted of cycles of lower limb ischemia induced by an arterial tourniquet cuff placed around the patient's thigh. In the RC treatment group, the cuff was inflated to 200 mm Hg or systolic pressure +25 mm Hg for 4 cycles of 5 min ischemia followed by 5 min reperfusion. In the control group, the blood pressure cuff was inflated to 25 mm Hg. Patients and medical staff were blinded to treatment allocation. The primary end-point was renal function measured by estimated glomerular filtration rate (eGFR) at 1 and 3 months posttransplant.Donor and recipient demographics were similar in both groups (P < 0.05). There were no significant differences in eGFR at 1 month (control 52 ±â€Š14 vs RC 54 ±â€Š17 mL/min; P = 0.686) or 3 months (control 50 ±â€Š14 vs RC 49 ±â€Š18 mL/min; P = 0.678) between the control and RC treatment groups. The RC technique did not cause any serious adverse effects.RC, using the protocol described here, did not improve renal function after live donor kidney transplantation.

Hydrogen sulfide reduces inflammation following abdominal aortic occlusion in rats.

BACKGROUND: Remote renal ischemia-reperfusion injury (IRI) following infra-renal aortic occlusion leads to acute kidney injury and systemic inflammation. Hydrogen sulfide is a mediator of IRI and can ameliorate tissue injury in many organ systems. Its role in vascular surgery has yet to be established. We assessed the role of hydrogen sulfide in a rodent model of aortic occlusion. METHODS: Wistar rats were divided into sham, control, and treatment groups (n = 6). Inflammation was assessed using a nonrecovery protocol. The infra-renal aorta was cross-clamped for 60 min and animals were reperfused for 120 min. Ten minutes before clamp release, treatment animals received hydrogen sulfide (10, 30, or 50 µg/kg) and control animals received 0.9% saline injected into the retroperitoneum. Renal injury and histology were assessed by a recovery protocol. The procedure was identical to the nonrecovery arm but with a single dose of hydrogen sulfide (30 µg/kg) and animals were recovered for 7 days. RESULTS: There was no difference in animal weight between the groups (P = 0.337). In the nonrecovery arm, there was a reduction in serum levels of tumor necrosis factor alpha in sulfide-treated animals compared with controls (909 ± 98 vs. 607 ± 159 pg/mL; P = 0.0038). There was also a reduction in myeloperoxidase-positive cells in renal tissue in the sulfide-treated animals compared with controls (8 ± 4 vs. 17 ± 9; P = 0.03). There was no difference in histological injury score or endothelin-1 levels. In the recovery arm, there was no difference in renal function, Kidney Injury Molecule-1 levels, or histological injury scores. CONCLUSION: Hydrogen sulfide has systemic and renal anti-inflammatory effects in remote IRI following aortic occlusion in rats.

Suprarenal graft fixation in endovascular abdominal aortic aneurysm repair is associated with a decrease in renal function.

INTRODUCTION: Suprarenal endograft fixation is routinely used in the endovascular repair of abdominal aortic aneurysms (EVAR) to enhance proximal endograft attachment but can be associated with an adverse outcome in renal function. This prospective study assessed the effect of suprarenal fixation on serum creatinine concentration and estimated glomerular filtration rate (eGFR), calculated by the Modified Diet in Renal Disease equation, 12 months after elective EVAR. METHODS: Patients undergoing elective EVAR were divided into suprarenal vs infrarenal fixation groups matched for age, sex, smoking, and aneurysm diameter. Serum creatinine and eGFR were measured at baseline, 6, and 12 months. RESULTS: Included were 92 patients (two women) with a mean age of 71 ± 7 years, with 46 in each group. No device-related complications were noted. Serum creatinine did not differ significantly between groups at 6 (P = .24) or 12 (P = .08) months but significantly increased in the suprarenal group at 12 months (1.08 ± 0.36 to 1.16 ± 0.36 mg/dL; P < .001) vs baseline. The eGFR (mL/min/1.73 m(2)) did not differ significantly at baseline between the suprarenal (85 ± 27) and infrarenal (80 ± 28; P = .33) groups or at 6 months (88 ± 29 vs 77 ± 24, respectively; P = .07). At 12 months, the suprarenal group had a lower eGFR (73 ± 23) than the infrarenal group (84 ± 26; P = .027). The eGFR at 12 months showed a significant decrease in the suprarenal (80 ± 28 to 73 ± 23; P < .001) but not in the infrarenal group (85 ± 27 to 84 ± 26; P = .48). The drop in eGFR differed significantly at 12 months in the infrarenal vs the suprarenal (0.82 vs -6.94; P < .001) group. No patient progressed to end-stage renal disease or disclosed a drop in eGFR > 30%. CONCLUSIONS: In contrast to previous studies, this study suggests that suprarenal endograft fixation in elective EVAR is associated with a drop in eGFR at 12 months.

Anemia is associated with mortality following endovascular repair of abdominal aortic aneurysm.

AIM: The aim of this study was to compare midterm mortality between anemic and nonanemic patients undergoing endovascular repair of abdominal aortic aneurysm and to assess a correlation with markers of inflammation. METHODS: Anemia was defined as hemoglobin <13 (men) and <12 g/dL (women). The impact of anemia and inflammatory markers on mortality was assessed using Kaplan-Meier curves and Cox regression. RESULTS: A total of 224 patients (12 females [5.36%]; age: 69.73 ± 8.72 years) were included; 102 (45.53%) were anemic. Median follow-up was 17 months (interquartile range: 7-25 months). Nine patients died (1.79%; 8 anemic vs 1 nonanemic). Survival was lower for patients with anemia (log-rank, P = .01). White blood cell count and C-reactive protein (CRP) differed significantly (P < .001 and P = .01). Anemia and CRP were associated with decreased survival (Cox regression, P = .01, hazard ratio [HR]: 0.35, 95% confidence interval: 0.14-0.84 and P = .002, HR: 1.18, 95% CI: 1.06-1.31). CONCLUSION: Patients with anemia had decreased survival over the midterm; inflammatory markers were higher among this group.

Early urinary biomarkers of warm and cold ischemic injury in an experimental kidney model.

BACKGROUND: Early urinary biomarkers may be useful in determining the severity of ischemic injury in donation after circulatory death (DCD) kidneys. The aim of this study was to evaluate the efficacy of a collective series of urinary biomarkers in relation to the warm and cold ischemic intervals. METHODS: Porcine kidneys were retrieved after 0, 10, and 25 min of warm ischemia (WI), then preserved by static cold storage (CS) for period of 2 and 18 h. After preservation, kidneys were reperfused on an isolated organ perfusion system to assess renal function and injury. Levels of IL-6, TNFα, endothelin-1 (ET-1), and neutrophil gelatinase-associated lipocalin (NGAL) were measured in urine samples after 3 h of reperfusion. RESULTS: There was no significant difference in renal functional parameters or urinary biomarkers between the WI times when kidneys were stored for 2 h (P > 0.05). After 18 h CS, kidneys with 10 and 25 min of WI demonstrated a significant decline in renal function compared with kidneys without WI (P < 0.05). Levels of ET-1 and NGAL were significantly higher in kidneys with 25 min WI (25 m ET-1, 30.1 ± 21.2, versus 0 m 2.25 ± 1.5 pg/mL; P = 0.002: NGAL, 25 m 77 ± 51 versus 0 m 10 ± 0.1 pg/mL; P = 0.005). Levels of IL-6 and TNFα were significantly higher in kidneys with 10 and 25 min of WI (P = 0.001, 0.001). CONCLUSION: Early urinary biomarkers are a useful means to determine graft injury. ET-1 and NGAL are more accurate in predicting the severity of ischemic injury compared with inflammatory markers.