Renal damage after liver transplantation.

BACKGROUND: Patients following liver transplantation are at risk to develop acute kidney injury (AKI). The aim of our study was to assess risk factors for the development of AKI and the impact of AKI on the outcome of patients after liver transplantation (OLT). PATIENTS AND METHODS: In this retrospective study, we analyzed 149 patients undergoing OLT from 1/2004 to 12/2007. AKI was defined according to the KDIGO definition representing the AKIN and the RIFLE classification, and according to the need for renal replacement therapy (RRT). RESULTS: According to the AKIN criteria alone 14 patients, according to the RIFLE criteria alone no patient and according to both definitions 30 patients developed AKI. RRT was required in 54 patients experiencing AKI, whereas 51 patients did not develop AKI. Pre OLT serum creatinine (SCr) significantly predicted the development of AKI requiring RRT, but not AKI without RRT requirement. Survival rate was significantly inferior after 28 days, one or three years in patients with AKI requiring RRT (70.4, 46.4, 44.4% vs. 100, 92.2, 90.2%, P < 0.001). There was no difference in survival between patients experiencing AKI according to the RIFLE or AKIN criteria without RRT requirement and patients without AKI. CONCLUSION: Pre OLT renal dysfunction assessed by SCr was the most important risk factor predicting severe forms of AKI, but not milder forms of AKI. AKI requiring RRT had a detrimental impact on patients' survival, whereas milder forms of AKI were not associated with a worse outcome.

Impact of low-level BK polyomavirus viremia on intermediate-term renal allograft function.

BACKGROUND: BK polyomavirus (BKPyV)-associated nephropathy (PyVAN) is a significant cause of premature renal transplant failure. High-level BKPyV viremia is predictive for PyVAN; however, low-level BKPyV viremia does not necessarily exclude the presence of PyVAN. As data are limited regarding whether or not low-level BKPyV viremia has an effect on intermediate-term graft outcome, this study analyzes the impact of low-level BKPyV viremia on intermediate-term graft function and outcome compared with high-level viremia and non-viremic patients. METHODS: All renal transplant patients received follow-up examinations at the Department of Nephrology, University Hospital Essen. Patients were screened for BKPyV viremia and stratified into three groups according to their maximum BKPyV load in serum (low-level viremia, high-level viremia, and no viremia). RESULTS: In 142 of 213 (67%) patients, BKPyV was never detected in serum; 42 of 213 (20%) patients were found positive for low-level viremia (≤104 copies/mL); and 29 of 213 (13%) patients showed high-level viremia (>104 copies/mL). No significant differences regarding transplant function and graft failure were observed between patients without BKPyV viremia (delta estimated glomerular filtration rate [eGFR] +0.1 mL/min [month 1 vs last visit at month 44]) and patients with low-level BKPyV viremia (delta eGFR -1.7 mL/min). In patients with high-level viremia, transplant function was significantly restricted (delta eGFR -6.5 mL/min) compared with low-level viremia until the last visit at 44 ± 9.7 months after transplantation. Although the graft function and graft loss were worse in the high-level viremia group compared with no viremia (eGFR 37 vs 45 mL/min), the difference was not significant. CONCLUSIONS: High-level viremia was associated with impaired graft function. In contrast, low-level BKPyV viremia had no significant impact on intermediate-term graft function.

Susceptibility of HLA-E*01:03 Allele Carriers to Develop Cytomegalovirus Replication After Living-Donor Kidney Transplantation.

Cytomegalovirus (CMV) causes serious complications among solid organ transplant recipients. We report the positive correlation between the presence of the HLA-E*01:03 allele in living-donor kidney recipients and CMV reactivation during the first year after transplantation. Thus, HLA-E genotyping may help identify CMV replication-prone patients who require individualized patient-based CMV management.

Resveratrol Does Not Protect from Ischemia-Induced Acute Kidney Injury in an in Vivo Rat Model.

BACKGROUND/AIMS: The natural polyphenol resveratrol (RSV) has been shown to ameliorate ischemia/reperfusion (I/R)-induced damage. Therefore, a rat model of I/R-induced AKI equipped with intensive monitoring was utilized to examine direct renal protection by RSV in vivo. METHODS: AKI was induced by bilateral renal clamping (45 min) followed by reperfusion (3 h). Solvent-free RSV was continuously infused intravenously (0.056 and 0.28 mg/kg) in a total volume of 7 ml/kg/h starting from 30 min before renal clamping. At a mean arterial blood pressure below 70 mmHg for more than 5 min, bolus injections of 0.5 ml 0.9% NaCl solution were administered repetitively (max. 5 ml/kg/h). RESULTS: No differences could be found between normoxic control groups with/without RSV. Bilateral renal clamping and subsequent reperfusion caused a progressive rise in creatinine, cystatin C, and CK, a decrease in cellular ATP content and diuresis. Infusion of RSV increased sirtuin 1 expression after ischemia/reperfusion and was associated with decreased blood pressure during ischemia and early reperfusion accompanied by an increased requirement of bolus injections as well as with increased expression of TNFα. CONCLUSION: RSV did not exert protective effects on I/R-induced AKI in the present short-term in vivo rat model. The lack of protection is potentially connected to aggravation of blood pressure instability.

Transfemoral transcatheter aortic valve implantation in patients with end-stage renal disease and kidney transplant recipients.

Transcatheter aortic valve implantation (TAVI) has evolved to a treatment of choice in high-risk patients and is therefore ideal for patients with advanced chronic kidney disease, as patients with end-stage renal disease and kidney transplant recipients. Especially, outcome of this special patient group is very important. 22 patients with chronic kidney disease stage 5 undergoing intermittent hemodialysis treatment (CKD 5D) and 8 kidney transplant recipients (KT) with severe aortic valve stenosis underwent transfemoral TAVI. TAVI was successfully performed in all patients. Postinterventional acute kidney injury (AKI) occurred in four kidney transplant recipients (KDIGO grade 1: n = 3, grade 3: n = 1) but creatinine/eGFR returned to baseline values in all patients. Short-term (30-day) mortality was 3% (1 patient in CKD 5D group). KT had a higher 2-year mortality than CKD5D patients (31% vs. 53%; p = 0.309), and cause of death was non-cardiac because of sepsis in all cases. The amount of contrast medium during TAVI was not associated with the development of acute kidney injury. TAVI is feasible in patients with CKD5D and in KT. Postinterventional AKI in these patients is often mild and does not impact renal function at day 30, while infection/ sepsis is the leading cause of mid-term mortality.

Recipient HLA-G +3142 CC Genotype and Concentrations of Soluble HLA-G Impact on Occurrence of CMV Infection after Living-Donor Kidney Transplantation.

The expression modulation of the immunosuppressive non-classical Human leukocyte antigen-G (HLA-G) molecule and its soluble isoforms is an immune evasion strategy being deployed by cytomegalovirus (CMV). The +3142 C>G single nucleotide polymorphism (SNP) located within the 3' untranslated region (3'UTR) is of crucial importance for the regulation of HLA-G expression. Therefore, we analyzed the influence of the +3142 C>G HLA-G SNP on the occurrence of CMV infection in a cohort of 178 living-donor kidney recipients and their 178 corresponding donors. In addition, soluble HLA-G (sHLA-G) levels were quantified before and after transplantation. The presence of the HLA-G +3142 CC genotype in recipients, but not donors of our cohort as along with elevated sHLA-G levels (≥ 6.1 ng/mL) were associated with higher susceptibility to CMV infection after transplantation. Our results provided evidence that i) HLA-G is implicated in the establishment of CMV after living-donor kidney transplantation and ii) recipient HLA-G +3142 CC genotype and sHLA-G concentration levels could represent important predictive risk markers for CMV infection.

Characterization of injury in isolated rat proximal tubules during cold incubation and rewarming.

Organ shortage leads to an increased utilization of marginal organs which are particularly sensitive to storage-associated damage. Cold incubation and rewarming-induced injury is iron-dependent in many cell types. In addition, a chloride-dependent component of injury has been described. This work examines the injury induced by cold incubation and rewarming in isolated rat renal proximal tubules. The tissue storage solution TiProtec® and a chloride-poor modification, each with and without iron chelators, were used for cold incubation. Incubation was performed 4°C for up to 168 h, followed by rewarming in an extracellular buffer (3 h at 37°C). After 48, 120 and 168 h of cold incubation LDH release was lower in solutions containing iron chelators. After rewarming, injury increased especially after cold incubation in chelator-free solutions. Without addition of iron chelators LDH release showed a tendency to be higher in chloride-poor solutions. Following rewarming after 48 h of cold incubation lipid peroxidation was significantly decreased and metabolic activity was tendentially better in tubules incubated with iron chelators. Morphological alterations included mitochondrial swelling and fragmentation being partially reversible during rewarming. ATP content was better preserved in chloride-rich solutions. During rewarming, there was a further decline of ATP content in the so far best conditions and minor alterations under the other conditions, while oxygen consumption was not significantly different compared to non-stored control tubules. Results show an iron-dependent component of preservation injury during cold incubation and rewarming in rat proximal renal tubules and reveal a benefit of chloride for the maintenance of tubular energy state during cold incubation.

Granzyme B producing B-cells in renal transplant patients.

OBJECTIVES: A separate subset of Granzyme B (GrB) producing B-cells regulating T-cell mediated immunity has been identified. In the present study, we investigated the role of GrB+ B-cells in renal transplant patients (RTX). METHODS: 12 healthy controls (HC) and 26 RTX patients were enrolled. In addition, 19 healthy volunteers treated with cyclosporine A (CsA) were enrolled. GrB+ B-cells were determined via flow cytometry. RESULTS: RTX Patients showed a diminished fraction of GrB+ B-cells as compared to HC. CsA treatment of healthy volunteers had no impact on the development of GrB+ B-cells. RTX patients with a history of allograft rejection showed an increased frequency of GrB+ B-cells. RTX patients with at least one episode of CMV viremia tended to have lower GrB+ B-cells as compared to patients without viremic episodes. CONCLUSION: We demonstrate that treatment with CsA does not impair the development of GrB+ B-cells. GrB+ B-cells may have a dual role in renal transplantation as regulatory cells to maintain allospecific tolerance and as effector cells enhancing viral control.

Increased resistance of gram-negative urinary pathogens after kidney transplantation.

BACKGROUND: Urinary tract infection is the most common complication after kidney transplantation. It can cause severe sepsis and transplant loss. Emergence of drug resistance among gram-negative urinary pathogens is the current challenge for urinary tract infection treatment after kidney transplantation. METHODS: This study analyzes the antimicrobial susceptibility of gram-negative urinary pathogens after kidney transplantation from 2009 to 2012 at the Transplant Outpatient Clinic of the University Hospital Essen, Germany. Kidney transplant patients at the University Hospital Essen receive regular follow up examinations after transplantation. Midstream urines were examined for bacteriuria at each follow up visit. RESULTS: From 2009 to 2012 15.741 urine samples were obtained from 859 patients. In 2985 (19%) samples bacterial growth was detected. The most frequently detected gram-negative bacteria were E.coli 1109 (37%), Klebsiella spp. 242 (8%) and Pseudomonas aeruginosa 136 (4.5%). Klebsiella spp. showed a significant increase of resistance to trimethoprim-sulfamethoxazole by 19% (p = 0.02), ciprofloxacin by 15% (p = 0.01) and ceftazidime by 17% (p = 0.004). E.coli and P. aeruginosa isolates presented no significant differences of antimicrobial susceptibility to the analyzed antibiotics. CONCLUSIONS: Antimicrobial resistance of Klebsiella spp. increased significant to trimethoprim-sulfamethoxazole, ciprofloxacin and ceftazidime from 2009 to 2012.

Citrate shows protective effects on cardiovascular and renal function in ischemia-induced acute kidney injury.

BACKGROUND: Ischemia and reperfusion (I/R) is one of the major causes of acute kidney injury (AKI). Citrate reduces hypoxia-induced mitochondrial energetic deficits in isolated proximal tubules. Moreover, citrate anticoagulation is now frequently used in renal replacement therapy. In the present study a rat model of I/R-induced AKI was utilized to examine renal protection by citrate in vivo. METHODS: AKI was induced by bilateral renal clamping (40 min) followed by reperfusion (3 h). Citrate was infused at three different concentrations (0.3 mmol/kg/h; 0.6 mmol/kg/h and 1.0 mmol/kg/h) continuously for 60 min before and 45 min after ischemia. Plasma calcium concentrations were kept stable by infusion of calcium gluconate. The effect of citrate was evaluated by biomonitoring, blood and plasma parameters, histopathology and tissue ATP content. RESULTS: In comparison to the normoxic control group bilateral renal ischemia led to an increase of creatinine and lactate dehydrogenase activity and a decrease in tissue ATP content and was accompanied by a drop in mean arterial blood pressure. Infusion of 1.0 mmol/kg/h citrate led to lower creatinine and reduced LDH activity compared to the I/R control group and a tendency for higher tissue ATP content. Pre-ischemic infusion of 1.0 mmol/kg/h citrate stabilized blood pressure during ischemia. CONCLUSIONS: Citrate has a protective effect during I/R-induced AKI, possibly by limiting the mitochondrial deficit as well as by beneficial cardiovascular effects. This strengthens the rationale of using citrate in continuous renal replacement therapy and encourages consideration of citrate infusion as a therapeutic treatment for AKI in humans.

Mitochondrial Impairment as a Key Factor for the Lack of Attachment after Cold Storage of Hepatocyte Suspensions.

Isolated primary hepatocytes, which are widely used for pharmacological and clinical purposes, usually undergo certain periods of cold storage in suspension during processing. While adherent hepatocytes were shown previously to suffer iron-dependent cell death during cold (4 °C) storage and early rewarming, we previously found little iron-dependent hepatocyte death in suspension but severely decreased attachment ability unless iron chelators were added. Here, we focus on the role of mitochondrial impairment in this nonattachment of hepatocyte suspensions. Rat hepatocyte suspensions were stored in a chloride-poor, glycine-containing cold storage solution with and without iron chelators at 4 °C. After 1 wk of cold storage in the basic cold storage solution, cell viability in suspension was unchanged, while cell attachment was decreased by >80%. In the stored cells, a loss of mitochondrial membrane potential (MMP), a decrease in adenosine triphosphate (ATP) content (2 ± 2 nmol/106 cells after cold storage, 5 ± 3 nmol/106 cells after rewarming vs. control 29 ± 6 nmol/106 cells), and a decrease in oxygen consumption (101 ± 59 pmol sec-1 per 106 cells after rewarming vs. control 232 ± 83 pmol sec-1 per 106 cells) were observed. Addition of iron chelators to the cold storage solution increased cell attachment to 53% ± 20% and protected against loss of MMP, and cells were able to partially regenerate ATP during rewarming (15 ± 10 nmol/106 cells). Increased attachment could also be achieved by addition of the inhibitor combination of mitochondrial permeability transition, trifluoperazine + fructose. Attached hepatocytes displayed normal MMP and mitochondrial morphology. Additional experiments with freshly isolated hepatocytes confirmed that impaired energy production-as elicited by an inhibitor of the respiratory chain, antimycin A-can decrease cell attachment without decreasing viability. Taken together, these results suggest that mitochondrial impairment with subsequent energy deficiency is a key factor for the lack of attachment of cold-stored hepatocyte suspensions.

Acute kidney injury in liver transplant candidates: a position paper on behalf of the Liver Intensive Care Group of Europe.

INTRODUCTION: Acute kidney injury is associated with high mortality in the perioperative period of liver transplantation. The aim of this position paper was to provide an up-to-date overview with special emphases on diagnosis, risk factors, and treatment. EVIDENCE ACQUISITION: The Liver Intensive Care Group of Europe nominated a panel of recognized international experts who reviewed the available literature published from 1990 to January 2016 and produced clinical recommendations. The level of evidence and strength of recommendation were judged according to the Grading of Recommendations Assessment Development and Evaluation system. EVIDENCE SYNTHESIS: Diagnosis of AKI should be based on the KDIGO criteria. The preoperative risk factors are more related to the patient's predisposing factors and post-operative risk factors tend to be difficult to control. Therefore, focusing on intra-operative risk factors it would be important to maintain an adequate hemodynamics and to keep inferior vena cava clamping as short as possible. Biomarkers to identify AKI at an early stage are available; however, there is a lack of robust data that indicates their true beneficial effect. Intraoperative renal replacement therapy may be beneficial in some selective cases whereas its postoperative timing is still under debate. CONCLUSIONS: Perioperative liver transplant risk factors for acute kidney injury are difficult to control. Therefore, the focus should be on intra-operative hemodynamics and nephrotoxic drugs avoidance. Prospective randomized trials are needed to show the beneficial effect of early replacement therapy. In this context, the new biomarkers would be helpful in identifying kidney injury earlier.

Successful Treatment of Chronic Hepatitis C Virus Infection With Sofosbuvir and Ledipasvir in Renal Transplant Recipients.

BACKGROUND: Treatment of chronic hepatitis C virus (HCV) infection after renal allograft transplantation has been an obstacle because of contraindications associated with IFN-based therapies. Direct-acting antiviral agents are highly efficient treatment options that do not require IFN and may not require ribavirin. Therefore, we assessed the efficacy and safety of sofosbuvir and ledipasvir in renal transplant patients with chronic HCV infection. METHODS: Fifteen renal allograft recipients with therapy-naive HCV genotype (GT) 1a, 1b, or 4 were treated with the combination of sofosbuvir and ledipasvir without ribavirin for 8 or 12 weeks. Clinical data were retrospectively analyzed for viral kinetics and for renal and liver function parameters. Patients were closely monitored for trough levels of immunosuppressive agents, laboratory values, and potential adverse effects. RESULTS: Ten patients (66%) exhibited a rapid virologic response within 4 weeks (HCV GT1a, n = 4; HCV GT1b, n = 6). The other 5 patients exhibited a virologic response within 8 (HCV GT 1b, n = 4) or 12 weeks (HCV GT4, n = 1). One hundred percent of patients exhibited sustained virologic response at week 12 after the end of treatment. Clinical measures of liver function improved substantially for all patients. Adverse events were scarce; renal transplant function and proteinuria remained stable. Importantly, dose adjustments for tacrolimus were necessary for maintaining sufficient trough levels. CONCLUSIONS: The described regimen appears to be safe and effective for patients after renal transplant and is a promising treatment regimen for eradicating HCV in this patient population.

Association of high HLA-E expression during acute cellular rejection and numbers of HLA class I leader peptide mismatches with reduced renal allograft survival.

Non-classical Human Leukocyte Antigen (HLA)-E preferentially presents leader peptides derived from classical HLA-class I molecules. HLA-E can trigger opposed immune responses by interacting with inhibitory NKG2A or by activating NKG2C receptors on NK and T-cells. We studied the impact of HLA-E on renal allograft survival during acute cellular rejection. HLA-E expression was up-regulated in acute cellular rejection (ACR) biopsies (n=12) compared to biopsies from 13 renal allografts with no rejection-signs. HLA-E up-regulation was correlated with numbers of HLA-class I leader peptide mismatches (p=0.04). CD8+ and CD56+ infiltrating cells correlated with HLA-E expression (p<0.0001 and p=0.0009, respectively). Activating NKG2C receptor dominated on effector cells in biopsies and peripheral blood during ACR potentially allowing HLA-E-mediated immune activation. Moreover, HLA-E expression correlated with deterioration in renal allograft function (p<0.008) and reduced allograft survival (p=0.002). Our findings provide evidence that during renal allograft rejection HLA-E along with high numbers of mismatched HLA-class I leader peptides might represent additional targets for immune-activating responses.

[Acute kidney injury: update 2016]. / Akutes Nierenversagen--Update 2016.

Acute kidney injury is still defined by the functional parameters diuresis and serum creatinine. New biomarkers can be sensible additions for the detection of pathogenesis and prognosis. Risk stratification is also very useful for identification of patients at risk for the development of acute kidney injury. This is of increased importance as usual therapeutic treatments are rare and long-term effects are devastating.

The role of glycine in regulated cell death.

The cytoprotective effects of glycine against cell death have been recognized for over 28 years. They are expressed in multiple cell types and injury settings that lead to necrosis, but are still not widely appreciated or considered in the conceptualization of cell death pathways. In this paper, we review the available data on the expression of this phenomenon, its relationship to major pathophysiologic pathways that lead to cell death and immunomodulatory effects, the hypothesis that it involves suppression by glycine of the development of a hydrophilic death channel of molecular dimensions in the plasma membrane, and evidence for its impact on disease processes in vivo.

Edema, Hyperpigmentation, Induration: 3 Skin Signs Heralding Danger in Patients on Maintenance Hemodialysis.

Skin changes are common in patients on dialysis. This study focused on putative associations of specific skin findings with comorbidities and mortality.We performed a retrospective analysis of data from 508 patients on maintenance hemodialysis therapy in 7 centers in the German State of North Rhine Westphalia. Data had been collected by interview, from patient files, and from targeted physical examination in an earlier prospective study screening hemodialysis patients for the presence of nephrogenic systemic fibrosis. While on dialysis, patients' extremities had been examined for any of the following: edematous skin at the lower extremities, hyperpigmentation, induration, and xerosis cutis. Our present data analyses focused on associated mortality and comorbidities.Five hundred eight patients (median age 71 years, range 20.0-95.9; n = 292 men) had agreed to participate in the initial study: 48% (n = 243) were diabetics and 46% (n = 232) had been diagnosed with coronary heart disease. On examination, 86% of patients (n = 439) presented with at least 1 of the prespecified skin changes. Skin edema (n = 89; 18%), hyperpigmentation (n = 74; 15%), and induration (n = 9; 2%) were independently associated with increased mortality over 24 months (P < 0.002, P < 0.030, and P < 0.020, respectively).In our study, prespecified skin changes indicated an increased mortality risk in patients on chronic hemodialysis. Routinely assessing the skin of dialysis patients represents a simple, reliable, and cost effective means of identifying those at greatest risk.

From the nephrologist's point of view: diversity of causes and clinical features of acute kidney injury.

Acute kidney injury (AKI) is a clinical syndrome with multiple entities. Although AKI implies renal damage, functional impairment or both, diagnosis is solely based on the functional parameters of serum creatinine and urine output. The latest definition was provided by the Kidney Disease Improving Global Outcomes (KDIGO) working group in 2012. Independent of the underlying disease, and even in the case of full recovery, AKI is associated with an increased morbidity and mortality. Awareness of the patient's individual risk profile and the diversity of causes and clinical features of AKI is pivotal for optimization of prophylaxes, diagnosis and therapy of each form of AKI. A differentiated and individualized approach is required to improve patient mortality, morbidity, long-term kidney function and eventually the quality of life. In this review, we provide an overview of the different clinical settings in which specific forms of AKI may occur and point out possible diagnostic as well as therapeutic approaches. Secifically AKI is discussed in the context of non-kidney organ failure, organ transplantation, sepsis, malignancy and autoimmune disease.

[Hyperhydration and dialysis in acute kidney failure]. / Überwässerung und Dialyse beim akuten Nierenversagen.

Despite the advances in critical care medicine, the hospital mortality in patients with acute kidney injury (AKI) requiring dialysis remains high. Depending on the underlying disease the in-house mortality is reported to be up to 80%. Several observational studies demonstrated an association between mortality and fluid overload. A primary mechanism of interest is that fluid overload causes tissue edema and subsequent reduction of perfusion, oxygenation and nutrient delivery. This results in further renal damage. In addition, fluid overload-related dilution within the extracellular space causes artificially low serum creatinine, which masks AKI diagnosis. As a consequence, renal protective management strategies are deferred, which further aggravates kidney injury. This aggravation of renal damage subsequently increases the mortality. This review discusses the role of fluid overload for outcomes in critically ill patients as described in the current literature and assesses criteria for the initiation of renal replacement therapy in this critically ill population.