Implication of transcription factor FOXD2 dysfunction in syndromic congenital anomalies of the kidney and urinary tract (CAKUT).

Congenital anomalies of the kidney and urinary tract (CAKUT) are the predominant cause for chronic kidney disease below age 30 years. Many monogenic forms have been discovered due to comprehensive genetic testing like exome sequencing. However, disease-causing variants in known disease-associated genes only explain a proportion of cases. Here, we aim to unravel underlying molecular mechanisms of syndromic CAKUT in three unrelated multiplex families with presumed autosomal recessive inheritance. Exome sequencing in the index individuals revealed three different rare homozygous variants in FOXD2, encoding a transcription factor not previously implicated in CAKUT in humans: a frameshift in the Arabic and a missense variant each in the Turkish and the Israeli family with segregation patterns consistent with autosomal recessive inheritance. CRISPR/Cas9-derived Foxd2 knockout mice presented with a bilateral dilated kidney pelvis accompanied by atrophy of the kidney papilla and mandibular, ophthalmologic, and behavioral anomalies, recapitulating the human phenotype. In a complementary approach to study pathomechanisms of FOXD2-dysfunction-mediated developmental kidney defects, we generated CRISPR/Cas9-mediated knockout of Foxd2 in ureteric bud-induced mouse metanephric mesenchyme cells. Transcriptomic analyses revealed enrichment of numerous differentially expressed genes important for kidney/urogenital development, including Pax2 and Wnt4 as well as gene expression changes indicating a shift toward a stromal cell identity. Histology of Foxd2 knockout mouse kidneys confirmed increased fibrosis. Further, genome-wide association studies suggest that FOXD2 could play a role for maintenance of podocyte integrity during adulthood. Thus, our studies help in genetic diagnostics of monogenic CAKUT and in understanding of monogenic and multifactorial kidney diseases.

DAAM2 Variants Cause Nephrotic Syndrome via Actin Dysregulation.

The discovery of >60 monogenic causes of nephrotic syndrome (NS) has revealed a central role for the actin regulators RhoA/Rac1/Cdc42 and their effectors, including the formin INF2. By whole-exome sequencing (WES), we here discovered bi-allelic variants in the formin DAAM2 in four unrelated families with steroid-resistant NS. We show that DAAM2 localizes to the cytoplasm in podocytes and in kidney sections. Further, the variants impair DAAM2-dependent actin remodeling processes: wild-type DAAM2 cDNA, but not cDNA representing missense variants found in individuals with NS, rescued reduced podocyte migration rate (PMR) and restored reduced filopodia formation in shRNA-induced DAAM2-knockdown podocytes. Filopodia restoration was also induced by the formin-activating molecule IMM-01. DAAM2 also co-localizes and co-immunoprecipitates with INF2, which is intriguing since variants in both formins cause NS. Using in vitro bulk and TIRF microscopy assays, we find that DAAM2 variants alter actin assembly activities of the formin. In a Xenopus daam2-CRISPR knockout model, we demonstrate actin dysregulation in vivo and glomerular maldevelopment that is rescued by WT-DAAM2 mRNA. We conclude that DAAM2 variants are a likely cause of monogenic human SRNS due to actin dysregulation in podocytes. Further, we provide evidence that DAAM2-associated SRNS may be amenable to treatment using actin regulating compounds.

Impaired Retinal Vessel Dilation Predicts Mortality in End-Stage Renal Disease.

RATIONALE: Patients with end-stage renal disease (ESRD) are characterized by increased cardiovascular (CV) and all-cause mortality due to advanced remodeling of the macro- and microvascular beds. OBJECTIVE: The aim of this study was to determine whether retinal microvascular function can predict all-cause and CV mortality in patients with ESRD. METHODS AND RESULTS: In the multicenter prospective observational ISAR (Risk Stratification in End-Stage Renal Disease) study, data on dynamic retinal vessel analysis (DVA) was available in a sub-cohort of 214 dialysis patients (mean age 62.6{plus minus}15.0; 32% female). Microvascular dysfunction was quantified by measuring maximum arteriolar (aMax) and venular dilation (vMax) of retinal vessels in response to flicker light stimulation. During a mean follow-up of 44 months, 55 patients died, including 25 CV and 30 non-CV fatal events. vMax emerged as a strong independent predictor for all-cause mortality. In the Kaplan-Meier analysis, individuals within the lowest tertile of vMax showed significantly shorter three-year survival rates than those within the highest tertile (66.9{plus minus}5.8% vs 92.4{plus minus}3.3%). Uni- and multivariate hazard ratios for all-cause mortality per SD increase of vMax were 0.62 [0.47;0.82] and 0.65[0.47;0.91], respectively. aMax and vMax were able to significantly predict nonfatal and fatal CV events (HR 0.74[0.57;0.97] and 0.78[0.61;0.99], respectively). CONCLUSIONS: Our results provide the first evidence that impaired retinal venular dilation is a strong and independent predictor of all-cause mortality in hemodialyzed ESRD patients. DVA provides added value for prediction of all-cause mortality and may be a novel diagnostic tool to optimize CV risk stratification in ESRD and other high-risk CV cohorts. CLINICAL TRIAL REGISTRATION: NCT01152892.

Kidney transplantation after rescue allocation-meticulous selection yields the chance for excellent outcome.

BACKGROUND: The small number of organ donors forces transplant centres to consider potentially suboptimal kidneys for transplantation. Eurotransplant established an algorithm for rescue allocation (RA) of kidneys repeatedly declined or not allocated within 5 h after procurement. Data on the outcomes and benefits of RA are scarce to date. METHODS: We conducted a retrospective 8-year analysis of transplant outcomes of RA offers based on our in-house criteria catalogue for acceptance and decline of organs and potential recipients. RESULTS: RA donors and recipients were both older compared with standard allocation (SA). RA donors more frequently had a history of hypertension, diabetes or fulfilled expanded criteria donor key parameters. RA recipients had poorer human leucocyte antigen (HLA) matches and longer cold ischaemia times (CITs). However, waiting time was shorter and delayed graft function, primary non-function and biopsy-proven rejections were comparable to SA. Five-year graft and patient survival after RA were similar to SA. In multivariate models accounting for confounding factors, graft survival and mortality after RA and SA were comparable as well. CONCLUSIONS: Facing relevant comorbidities and rapid deterioration with the risk of being removed from the waiting list, kidney transplantation after RA was identified to allow for earlier transplantation with excellent outcome. Data from this survey propose not to reject categorically organs from multimorbid donors with older age and a history of hypertension or diabetes to aim for the best possible HLA matching and to carefully calculate overall expected CIT.

Immunosuppressant quantification in intravenous microdialysate - towards novel quasi-continuous therapeutic drug monitoring in transplanted patients.

OBJECTIVES: Therapeutic drug monitoring (TDM) plays a crucial role in personalized medicine. It helps clinicians to tailor drug dosage for optimized therapy through understanding the underlying complex pharmacokinetics and pharmacodynamics. Conventional, non-continuous TDM fails to provide real-time information, which is particularly important for the initial phase of immunosuppressant therapy, e.g., with cyclosporine (CsA) and mycophenolic acid (MPA). METHODS: We analyzed the time course over 8 h of total and free of immunosuppressive drug (CsA and MPA) concentrations measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in 16 kidney transplant patients. Besides repeated blood sampling, intravenous microdialysis was used for continuous sampling. Free drug concentrations were determined from ultracentrifuged EDTA-plasma (UC) and compared with the drug concentrations in the respective microdialysate (µD). µDs were additionally analyzed for free CsA using a novel immunosensor chip integrated into a fluorescence detection platform. The potential of microdialysis coupled with an optical immunosensor for the TDM of immunosuppressants was assessed. RESULTS: Using LC-MS/MS, the free concentrations of CsA (fCsA) and MPA (fMPA) were detectable and the time courses of total and free CsA comparable. fCsA and fMPA and area-under-the-curves (AUCs) in µDs correlated well with those determined in UCs (r≥0.79 and r≥0.88, respectively). Moreover, fCsA in µDs measured with the immunosensor correlated clearly with those determined by LC-MS/MS (r=0.82). CONCLUSIONS: The new microdialysis-supported immunosensor allows real-time analysis of immunosuppressants and tailor-made dosing according to the AUC concept. It readily lends itself to future applications as minimally invasive and continuous near-patient TDM.

Exome Sequencing and Identification of Phenocopies in Patients With Clinically Presumed Hereditary Nephropathies.

RATIONALE & OBJECTIVE: Hereditary nephropathies are clinically and genetically heterogeneous disorders. For some patients, the clinical phenotype corresponds to a specific hereditary disease but genetic testing reveals that the expected genotype is not present (phenocopy). The aim of this study was to evaluate the spectrum and frequency of phenocopies identified by using exome sequencing in a cohort of patients who were clinically suspected to have hereditary kidney disorders. STUDY DESIGN: Cross-sectional cohort study. SETTING & PARTICIPANTS: 174 unrelated patients were recruited for exome sequencing and categorized into 7 disease groups according to their clinical presentation. They included autosomal dominant tubulointerstitial kidney disease, Alport syndrome, congenital anomalies of the kidney and urinary tract, ciliopathy, focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome, VACTERL association, and "other." RESULTS: A genetic diagnosis (either likely pathogenic or pathogenic variant according to the guidelines of the American College of Medical Genetics) was established using exome sequencing in 52 of 174 (30%) cases. A phenocopy was identified for 10 of the 52 exome sequencing-solved cases (19%), representing 6% of the total cohort. The most frequent phenocopies (n=5) were associated with genetic Alport syndrome presenting clinically as focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome. Strictly targeted gene panels (<25 kilobases) did not identify any of the phenocopy cases. LIMITATIONS: The spectrum of described phenocopies is small. Selection bias may have altered the diagnostic yield within disease groups in our study population. The study cohort was predominantly of non-Finnish European descent, limiting generalizability. Certain hereditary kidney diseases cannot be diagnosed by using exome sequencing (eg, MUC1-autosomal dominant tubulointerstitial kidney disease). CONCLUSIONS: Phenocopies led to the recategorization of disease and altered clinical management. This study highlights that exome sequencing can detect otherwise occult genetic heterogeneity of kidney diseases.

Repeated kidney re-transplantation-the Eurotransplant experience: a retrospective multicenter outcome analysis.

In Eurotransplant kidney allocation system (ETKAS), candidates can be considered unlimitedly for repeated re-transplantation. Data on outcome and benefit are indeterminate. We performed a retrospective 15-year patient and graft outcome data analysis from 1464 recipients of a third or fourth or higher sequential deceased donor renal transplantation (DDRT) from 42 transplant centers. Repeated re-DDRT recipients were younger (mean 43.0 vs. 50.2 years) compared to first DDRT recipients. They received grafts with more favorable HLA matches (89.0% vs. 84.5%) but thereby no statistically significant improvement of patient and graft outcome was found as comparatively demonstrated in 1st DDRT. In the multivariate modeling accounting for confounding factors, mortality and graft loss after 3rd and ≥4th DDRT (P < 0.001 each) and death with functioning graft (DwFG) after 3rd DDRT (P = 0.001) were higher as compared to 1st DDRT. The incidence of primary nonfunction (PNF) was also significantly higher in re-DDRT (12.7%) than in 1st DDRT (7.1%; P < 0.001). Facing organ shortage, increasing waiting time, and considerable mortality on dialysis, we question the current policy of repeated re-DDRT. The data from this survey propose better HLA matching in first DDRT and second DDRT and careful selection of candidates, especially for ≥4th DDRT.

Peritoneal magnesium elimination and its clinical relevance in peritoneal dialysis patients.

BACKGROUND: Dialysis patients are at increased risk for vascular calcification and cardiovascular disease. Emerging data suggests that magnesium might be protective for the vascular system in peritoneal dialysis (PD) patients as well. However, only limited data is available on the elimination of magnesium through PD treatment. This study aims to evaluate the peritoneal magnesium elimination characteristics in comparison to other small solutes and the influence of peritoneal transport status. MATERIALS AND METHODS: Peritoneal elimination of magnesium, blood-urea-nitrogen (BUN), and creatinine during a 4-hour peritoneal equilibration test (PET) was assessed in 30 stable PD patients. Absolute magnesium elimination was compared overall and between creatinine transport tertiles. RESULTS: Median age was 61 years, 50% of patients were male, 20% were on automated PD treatment. Serum magnesium was 0.84 mmol/L, and dialysate magnesium at the end of the PET was 0.57 mmol/L in the overall cohort and did not differ significantly between tertiles. The magnesium dialysate-to-plasma ratio was significantly different between the subgroups (lower tertile: median 0.60 (minimum 0.52, maximum 0.68) vs. middle tertile: 0.64 (0.58, 0.68) vs. upper tertile: 0.69 (0.67, 0.74), p < 0.001). The elimination per liter of dialysis fluid was also significantly different (8.6 (6.6, 10.4) vs. 9.4 (8.0, 10.5) vs. 10.6 (0.2, 11.8) mg/L, p = 0.002), as was the absolute removal during the 4-hour dwell (18.6 (15.8, 21.2) vs. 19.4 (13.4, 24.6) vs. 22.7 (19.6, 31.9) mg, p = 0.007, respectively). CONCLUSION: Peritoneal magnesium elimination is similar to small solute transport characteristics. However, the absolute differences among patients with slower and faster transport types are small. Therefore, magnesium supplementation in PD patients should be guided by serum magnesium concentrations rather than the amount of peritoneal elimination.

Comparison of 24-hour and Office Pulse Wave Velocity for Prediction of Mortality in Hemodialysis Patients.

BACKGROUND: Mortality in hemodialysis patients still remains unacceptably high. Enhanced arterial stiffness is a known cardiovascular risk factor, and pulse wave velocity (PWV) has proven to be a valid parameter to quantify risk. Recent studies showed controversial results regarding the prognostic significance of PWV for mortality in hemodialysis patients, which may be due to methodological issues, such as assessment of PWV in the office setting (Office-PWV). METHOD: This study cohort contains patients from the "Risk stratification in end-stage renal disease - the ISAR study," a multicenter prospective longitudinal observatory cohort study. We examined and compared the predictive value of ambulatory 24-hour PWV (24 h-PWV) and Office-PWV on mortality in a total of 344 hemodialysis patients. The endpoints of the study were all-cause and cardiovascular mortality. Survival analysis included Kaplan-Meier estimates and Cox regression analysis. RESULTS: During a follow-up of 36 months, a total of 89 patients died, 35 patients due to cardiovascular cause. Kaplan-Meier estimates for tertiles of 24 h-PWV and Office-PWV were similarly associated with mortality. In univariate Cox regression analysis, 24 h-PWV and Office-PWV were equivalent predictors for all-cause and cardiovascular mortality. After adjustment for common risk factors, only 24 h-PWV remained solely predictive for all-cause mortality (hazard ratio 2.51 [95% CI 1.31-4.81]; p = 0.004). CONCLUSIONS: Comparing both measurements, 24 h-PWV is an independent predictor for all-cause-mortality in hemodialysis patients beyond Office-PWV.

Mortality prediction in stable hemodialysis patients is refined by YKL-40, a 40-kDa glycoprotein associated with inflammation.

Chronic inflammation contributes to increased mortality in hemodialysis (HD) patients. YKL-40 is a novel marker of inflammation, tissue remodeling, and highly expressed in macrophages inside vascular lesions. Elevated levels of YKL-40 have been reported for HD patients but how it integrates into the proinflammatory mediator network as a predictor of mortality remains elusive. We studied serum YKL-40, Interleukin-6 (IL-6), high-sensitivity C-reactive protein, monocyte chemotactic protein-1 (MCP-1), and interferon-gamma induced protein-10 (IP-10) in 475 chronic hemodialysis patients. Patients were followed for mortality for a median of 37 [interquartile range: 25-49] months and checked for interrelation of the measured mediators. To plot cumulative incidence functions, patients were stratified into terciles per YKL-40, IL-6, MCP-1, and IP-10 levels. Multivariable Cox regression models were built to examine associations of YKL-40, IP-10, and MCP-1 with all-cause and cause-specific mortality. Net reclassification improvement was calculated for the final models containing YKL-40 and IL-6. Increased YKL-40 was independently associated with age, IP-10, and IL-6 serum levels. After adjustment for demographic and laboratory parameters, comorbidities, and IL-6, only YKL-40 significantly improved risk prediction for all-cause (hazard ratio 1.4; 95% confidence interval 1.1-1.8) and cardiovascular mortality (hazard ratio 1.5; 95% confidence interval 1.03-2.2). Thus, in contrast to other biomarkers of aberrant macrophage activation, YKL-40 reflects inflammatory activity, which is not covered by IL-6. Mechanistic and prospective studies are needed to test for causal involvement of YKL-40 and whether it might qualify as a therapeutic target.

Clinical validation of a novel enzyme-linked immunosorbent spot assay-based in vitro diagnostic assay to monitor cytomegalovirus-specific cell-mediated immunity in kidney transplant recipients: a multicenter, longitudinal, prospective, observational study.

Impaired cytomegalovirus (CMV)-specific cell-mediated immunity (CMV-CMI) is a major cause of CMV reactivation and associated complications in solid-organ transplantation. Reliably assessing CMV-CMI is desirable to individually adjust antiviral and immunosuppressive therapy. This study aimed to evaluate the suitability of T-Track® CMV, a novel IFN-γ ELISpot assay based on the stimulation of peripheral blood mononuclear cells with pp65 and IE-I CMV proteins, to monitor CMV-CMI following kidney transplantation. A prospective longitudinal multicenter study was conducted in 86 intermediate-risk renal transplant recipients. CMV-CMI, CMV viral load, and clinical complications were monitored over 6 months post-transplantation. Ninety-five percent and 88-92% ELISpot assays were positive pre- and post-transplantation, respectively. CMV-specific response was reduced following immunosuppressive treatment and increased in patients with graft rejection, indicating the ability of the ELISpot assay to monitor patients' immunosuppressive state. Interestingly, median pp65-specific response was ninefold higher in patients with self-clearing viral load compared to antivirally treated patients prior to first viral load detection (P < 0.001), suggesting that reactivity to pp65 represents a potential immunocompetence marker. Altogether, T-Track® CMV is a highly sensitive IFN-γ ELISpot assay, suitable for the immunomonitoring of CMV-seropositive renal transplant recipients, and with a potential use for the risk assessment of CMV-related clinical complications (ClinicalTrials.gov Identifier: NCT02083042).

A novel citrate-based protocol versus heparin anticoagulation for sustained low-efficiency dialysis in the ICU: safety, efficacy, and cost.

BACKGROUND: The high cost, complexity of the available protocols, and metabolic complications are the major barriers that impede the clinical utilization of regional citrate anticoagulation (RCA) for sustained low efficiency dialysis (SLED) in critically ill patients. By comparing a novel protocol for SLED using 30% citrate solution with common protocol using unfractionated heparin, this study aimed to provide new insights for clinical applications of RCA. METHODS: In this retrospective study, a total of 282 critically ill patients who underwent SLED with citrate and/or heparin anticoagulation in six adult ICUs were enrolled. These patients were divided into three groups based on the anticoagulation regimens they had received during the treatment in ICU: Group 1 (Citrate) had only received treatment with citrate anticoagulation (n=75); Group 2 (Heparin) only with heparin anticoagulation (n=79); and Group 3 (Both) with both citrate and heparin anticoagulation (n=128). We compared the mortality, metabolic complications as well as cost among these groups using different anticoagulation regimens. RESULTS: The in-hospital mortality did not significantly differ among groups (p> 0.1). However, three patients in heparin group suffered from severe bleeding which led to death, while none in citrate group. Overall, 976 SLED sessions with heparin anticoagulation and 808 with citrate were analyzed. The incidence of extracorporeal circuit clotting was significantly less in citrate (5%), as compared to that in heparin (10%) (p< 0.001). Metabolic complications and hypotension which led to interruption of SLED occurred more frequently, though not significantly, in citrate (p= 0.06, p= 0.23). Furthermore, with 30% citrate solution, the cost of anticoagulant was reduced by 70% in comparison to previously reported protocol using Acid Citrate Dextrose solution A (ACD-A). CONCLUSIONS: Our results indicated that anticoagulation regimens for SLED did not significantly affect the mortality of patients. Citrate anticoagulation was superior to heparin in preventing severe bleeding and circuit clotting. The protocol adopted in this study using 30% citrate solution was safe as well as efficacious. In the meantime, it was much more cost-efficient than other citrate-based protocol.

Unacceptable human leucocyte antigens for organ offers in the era of organ shortage: influence on waiting time before kidney transplantation.

BACKGROUND: The assignment of human leucocyte antigens (HLAs) against which antibodies are detected as unacceptable antigens (UAGs) avoids allocation of HLA- incompatible allografts. There is uncertainty as to what extent UAGs decrease the probability of receiving a kidney offer. METHODS: Kidney transplantations in 3264 patients on the waiting lists of six German transplant centres were evaluated for a period of at least 2 years. The proportion of excluded offers due to UAGs was calculated as virtual panel-reactive antibodies (vPRAs). RESULTS: In the common Eurotransplant Kidney Allocation Scheme, the transplant probability was unaffected by vPRAs in exploratory univariate analyses. In the multivariable model, a 1% increase in vPRA values was outweighed by an additional waiting time of 2.5 weeks. The model was confirmed using an external validation cohort of 1521 patients from seven centres. If only patients with standard risk were considered (e.g. no simultaneous transplantation of other organs), only 1.3 weeks additional waiting time was needed. In the Eurotransplant Senior Program, patients with vPRA values >50% had a strongly reduced transplant probability in the unadjusted analyses. In the multivariable model, a 1% increase in vPRA values was outweighed by an additional waiting time of 5 weeks. CONCLUSIONS: This study demonstrates that the assignment of UAGs decreases the transplant probability in both main Eurotransplant allocation programs because of insufficient compensatory mechanisms. At present, for immunized patients, a prolonged waiting time has to be weighed against the increased immunologic risk due to donor-specific antibodies not assigned as UAGs.

Serum uromodulin predicts graft failure in renal transplant recipients.

OBJECTIVE AND METHODS: Test the ability of serum uromodulin concentrations 1-3 months after renal transplantation to predict all-cause mortality (ACM) and graft loss (GL) in 91 patients. RESULTS: uromodulin predicted GL equivalently to the other markers studied: the risk for GL was reduced by 0.21 per one standard deviation (SD) increase (cystatin C: hazard ratio [HR] 4.57, creatinine: HR 4.53, blood-urea-nitrogen [BUN]: HR 2.50, estimated glomerular filtration rate [eGFR]: HR 0.10). In receiver-operating-characteristic (ROC) analysis, uromodulin predicted GL with an area-under-the curve of 0.782 at an optimal cut-off (OCO) of 24.0 ng/ml with a sensitivity of 90.0% and a specificity of 70.2%. CONCLUSION: Serum uromodulin predicted GL equivalently compared to conventional biomarkers of glomerular filtration.

Simultaneous Determination of Protein-Unbound Cyclosporine A and Mycophenolic Acid in Kidney Transplant Patients Using Liquid Chromatography-Tandem Mass Spectrometry.

BACKGROUND: Therapeutic drug monitoring (TDM) of immunosuppressants is essential to optimize patient care after organ transplantation. In blood, most immunosuppressive drugs are bound to plasma proteins or located inside blood cells. However, it is generally assumed that only protein-unbound (free) drug concentrations are pharmacologically active and could therefore better reflect the clinical outcome. Study data are still limited due to lacking rapid analytical methods. Therefore, a simple multiplex method for direct measurement of free cyclosporine A (CsA) and mycophenolic acid (MPA) has been developed. METHODS: The sample preparation included ultracentrifugation, followed by liquid-liquid extraction. Stable isotope labeled analogues of CsA and MPA were used as internal standards. The LC-MS/MS analysis was performed on a triple quadrupole mass spectrometer in the multiple reaction monitoring mode. The validated assay was used in a study of 40 blood samples from kidney transplant patients. RESULTS: The lower limits of quantification were 0.1 (CsA) and 0.5 ng/mL (MPA). Assay linearity was confirmed in the concentration ranges of 0.1-10.0 ng/mL (CsA) and 0.5-100 ng/mL (MPA). For both analytes, inaccuracy was ≤9.8% and imprecision was ≤7.8%. The extraction efficiency ranged between 91% and 96%. In the patient samples the average free CsA and MPA fractions were 5.8% (2.1%-16.8%) and 1.2% (0.5%-2.4%) respectively. CONCLUSIONS: A reliable and highly sensitive LC-MS/MS method as a new suitable tool for measuring protein-unbound CsA and MPA has been developed, validated and applied in kidney transplant patient samples. Now, larger studies can be conducted to investigate the benefit of free drug monitoring in transplant recipients.

Should belatacept be the centrepiece of renal transplantation?

Belatacept was developed to minimize cardiovascular risk and nephrotoxicity associated with calcineurin inhibitor (CNI)-based immunosuppression. Recently, 7-year data from the Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial (BENEFIT), a phase III study comparing belatacept with cyclosporine, have been published. While during the first year of belatacept the risk of acute rejection episodes was elevated, this seemingly had marginal consequences for long-term graft survival and function as well as patient survival.For patients at a low-immunological risk, this drug seems to be a safe and effective alternative to CNI-based immunosuppression. Whether the higher rates of acute rejection episodes in the first year outweigh the gain in long-term graft function is still debated. In particular, the lower incidence of donor-specific antibodies indicates that belatacept should not be considered as lower intensity immunosuppression over the long term.Therefore, should belatacept be the centrepiece of immunosuppression for renal patients?All randomized trials so far have focussed on patients at a low immunological risk. Furthermore, cyclosporine A (CsA), the comparator of belatacept in BENEFIT and the Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial-EXTended criteria donors (BENEFIT-EXT), is not the CNI of choice in modern transplantation. Furthermore, while at Year 7 the rate of cancer and infections was comparable with the CsA group, long-term data are missing on safety issues for a large number of patients. Thus, currently belatacept may be the drug of choice for a select group of patients, but not for everyone.This review highlights the benefits and uncertainties of the use of belatacept in kidney transplantation.

EMMPRIN expression is involved in the development of interstitial fibrosis and tubular atrophy in human kidney allografts.

BACKGROUND: Matrix metalloproteinases (MMP) are involved in the development of interstitial fibrosis and tubular atrophy (IF/TA) in renal disease. The synthesis of MMP is activated by the extracellular matrix metalloproteinases inducer protein (EMMPRIN). To analyze the role of EMMPRIN in IF/TA, we retrospectively detected EMMPRIN expression in specimens of human renal allografts with various levels of IF/TA. METHODS: Immunohistochemistry was performed to detect EMMPRIN expression. In a retrospective analysis, a total cohort of 50 specimens were divided according to BANFF-classification into four subgroups (0-3): no, mild (≤ 25%), moderate (26-50%), or severe (>50%) IF/TA. Among other parameters, renal function was analyzed and compared to EMMPRIN expression. RESULTS: In 24 of 38 biopsies, we detected positive EMMPRIN staining. All nephrectomy (n = 12) samples were negative for EMMPRIN. Positive staining in the biopsy samples was detectable on the basolateral side of tubular epithelial cells. EMMPRIN staining was negatively correlated with IF/TA (p < 0.001). We found significant differences between the mean EMMPRIN expression in IF/TA groups 0 and 3 (p = 0.021) and groups 1 and 3 (p = 0.004). Furthermore, we found significant correlations between EMMPRIN staining and renal function. CONCLUSION: Our data suggest that EMMPRIN is involved in the pathophysiology of IF/TA.

Plasma total C-terminal agrin fragment (tCAF) as a marker for kidney function in patients with chronic kidney disease.

BACKGROUND: Total C-terminal agrin fragment (tCAF) is a new biomarker that was previously correlated with kidney function. This article studies the validity of tCAF as a biomarker for kidney function in chronic kidney disease (CKD). METHODS: Plasma tCAF, serum creatinine (Cr), cystatin C (CyC), blood urea-nitrogen (BUN) concentrations and estimated glomerular filtration rate (eGFR CKD-EPIcrea-cystatin) were assessed in 426 individuals [71 without CKD (CKD 0°) and 355 CKD patients]. In addition to descriptive statistics, univariate correlation between tCAF and biomarkers/eGFR was calculated; multiple linear regression modeling was applied between logarithmic (log) tCAF and log eGFR and adjusted for demographic data. The same methods were used to analyze the association of demographic factors and the different biomarkers adjusted for eGFR. RESULTS: Mean tCAF levels were 1012.2±789.9 pM. tCAF correlated with all biomarkers/eGFR in univariate analysis (eGFR: r=-0.77, Cr: r=0.74, BUN: r=0.66, CyC: r=0.75). Linear regression modeling revealed an excellent coefficient estimate between log tCAF and log eGFR (CKD-EPIcrea-cystatin) (-0.91, p<0.001). tCAF was the parameter least associated with demographic parameters in both univariate and multivariate regression modeling (only with age, coefficient estimate r=-0.159, p=0.001 in multivariate regression). CONCLUSIONS: In conclusion, tCAF is a promising biomarker for the assessment of kidney function in CKD patients showing an excellent correlation with eGFR and being less influenced by demographic parameters compared to conventional biomarkers. These preliminary results encourage further evaluation of tCAF in larger CKD cohorts and other clinical settings such as acute renal failure.

Early postoperative C-terminal agrin fragment (CAF) serum levels predict graft loss and proteinuria in renal transplant recipients.

BACKGROUND: C-terminal agrin fragment (CAF), cleavage product of agrin, was previously correlated with kidney function in renal transplant patients. This article studies the predictive value of CAF for long-term outcomes in renal transplant recipients. METHODS: In this observational cohort study, serum CAF, creatinine and blood-urea-nitrogen (BUN) concentrations and eGFR (CKD-EPI) were assessed 1-3 months after transplantation in 105 patients undergoing kidney transplantation. Cox regression models were used to analyse the predictive value of all parameters concerning all-cause mortality (ACM), graft loss (GL), doubling of creatinine/proteinuria at the end of follow-up. RESULTS: Median follow-up time was 3.1 years. The mean concentrations were 191.9±152.4 pM for CAF, 176±96.8 µmol/L for creatinine, 12.6±6.2 mmol/L for BUN and 44.9±21.2 mL/min for CKD-EPI formula, respectively. In univariate analysis CAF and BUN concentrations predicted ACM (CAF: HR=1.003, 1.1-fold risk, p=0.043; BUN: HR=1.037, 1.3-fold risk, p=0.006). Concerning GL, CAF (HR=1.006, 3.1-fold risk, p<0.001), creatinine (HR=2.396, 2.6-fold risk, p<0.001), BUN (HR=1.048, 1.7-fold risk, p=0.001) and eGFR (CKD-EPI) (HR=0.941, 0.45-fold risk reduction, p=0.006) showed a statistically significant association. CAF was the only parameter significantly associated with doubling of proteinuria (HR=1.005, 1.7-fold risk, p<0.001). In multiple regression analysis (CAF only) the association remained significant for GL and doubling of proteinuria but not ACM. CONCLUSIONS: Early postoperative serum CAF appears to be a useful tool for the assessment of long-term outcomes in renal transplant recipients. Most importantly it represents a promising predictor for the development of proteinuria.