Urinary beta-2 microglobulin increases whereas TIMP-2 and IGFBP7 decline after unilateral nephrectomy in healthy kidney donors.

Early kidney injury may be detected by urinary markers, such as beta-2 microglobulin (B2M), tissue inhibitor of metalloproteinases-2 (TIMP-2), insulin-like growth factor-binding protein 7 (IGFBP7), kidney injury molecule-1 (KIM-1) and/or neutrophil gelatinase-associated lipocalin (NGAL). Of these biomarkers information on pathophysiology and reference ranges in both healthy and diseased populations are scarce. Differences in urinary levels of B2M, TIMP-2, IGFBP7, KIM-1 and NGAL were compared 24 h before and after nephrectomy in 38 living kidney donors from the REnal Protection Against Ischaemia-Reperfusion in transplantation study. Linear regression was used to assess the relation between baseline biomarker concentration and kidney function 1 year after nephrectomy. Median levels of urinary creatinine and creatinine standardized B2M, TIMP-2, IGFBP7, KIM-1, NGAL, and albumin 24 h before nephrectomy in donors were 9.4 mmol/L, 14 µg/mmol, 16 pmol/mmol, 99 pmol/mmol, 63 ng/mmol, 1390 ng/mmol and 0.7 mg/mmol, with median differences 24 h after nephrectomy of - 0.9, + 1906, - 7.1, - 38.3, - 6.9, + 2378 and + 1.2, respectively. The change of donor eGFR after 12 months per SD increment at baseline of B2M, TIMP-2, IGFBP7, KIM-1 and NGAL was: - 1.1, - 2.3, - 0.7, - 1.6 and - 2.8, respectively. Urinary TIMP-2 and IGFBP7 excretion halved after nephrectomy, similar to urinary creatinine, suggesting these markers predominantly reflect glomerular filtration. B2M and NGAL excretion increased significantly, similar to albumin, indicating decreased proximal tubular reabsorption following nephrectomy. KIM-1 did not change considerably after nephrectomy. Even though none of these biomarkers showed a strong relation with long-term donor eGFR, these results provide valuable insight into the pathophysiology of these urinary biomarkers.

Hypertension and diabetes, but not leptin and adiponectin, mediate the relationship between body fat and chronic kidney disease.

PURPOSE: Obesity may promote kidney damage through hemodynamic and hormonal effects. We investigated the association between body mass index (BMI), total body fat (TBF) and chronic kidney disease (CKD) and whether hypertension, diabetes, leptin and adiponectin mediated these associations. METHODS: In this cross-sectional analysis of the Netherlands Epidemiology of Obesity study, 6671 participants (45-65 y) were included. We defined CKD as eGFR <60 ml/min/1.73 m2 and/or moderately increased albuminuria. The percentage of mediation was calculated using general structural equation modeling, adjusted for potential confounding factors age, sex, smoking, ethnicity, physical activity and Dutch healthy diet index. RESULTS: At baseline mean (SD) age was 56 (6), BMI 26.3 (4.4), 44% men, and 4% had CKD. Higher BMI and TBF were associated with 1.08 (95%CI 1.05; 1.11) and 1.05-fold (95%CI 1.02; 1.08) increased odds of CKD, respectively. As adiponectin was not associated with any of the outcomes, it was not studied further as a mediating factor. The association between BMI and CKD was 8.5% (95%CI 0.5; 16.5) mediated by diabetes and 22.3% (95%CI 7.5; 37.2) by hypertension. In addition, the association between TBF and CKD was 9.6% (95%CI -0.4; 19.6) mediated by diabetes and 22.4% (95%CI 4.2; 40.6) by hypertension. We could not confirm mediation by leptin in the association between BMI and CKD (35.6% [95%CI -18.8; 90.3]), nor between TBF and CKD (59.7% [95%CI -7.1; 126.6]). CONCLUSION: Our results suggest that the relations between BMI, TBF and CKD are in part mediated by diabetes and hypertension.

Serum bile acids associate with liver volume in polycystic liver disease and decrease upon treatment with lanreotide.

BACKGROUND: Polycystic liver disease (PLD) is a common extrarenal manifestation of autosomal dominant polycystic kidney disease (ADPKD). Bile acids may play a role in PLD pathogenesis. We performed a post-hoc exploratory analysis of bile acids in ADPKD patients, who had participated in a trial on the effect of a somatostatin analogue. Our hypothesis was that serum bile acid levels increase in PLD, and that lanreotide, which reduces liver growth, may also reduce bile acid levels. Furthermore, in PLD, urinary excretion of bile acids might contribute to renal disease. METHODS: With liquid chromatography-mass spectrometry, 11 bile acids in serum and 6 in urine were quantified in 105 PLD ADPKD patients and 52 age-, sex-, mutation- and eGFR-matched non-PLD ADPKD patients. Sampling was done at baseline and after 120 weeks of either lanreotide or standard care. RESULTS: Baseline serum levels of taurine- and glycine-conjugated bile acids were higher in patients with larger livers. In PLD patients, multiple bile acids decreased upon treatment with lanreotide but remained stable in untreated subjects. Changes over time did not correlate with changes in liver volume. Urine bile acid levels did not change and did not correlate with renal disease progression. CONCLUSION: In ADPKD patients with PLD, baseline serum bile acids were associated with liver volume. Lanreotide reduced bile acid levels and has previously been shown to reduce liver volume. However, in this study, the decrease in bile acids was not associated with the change in liver volume.

Cell-free DNA measurement of three genomes after allogeneic MSC therapy in kidney transplant recipients indicates early cell death of infused MSC.

Introduction: Mesenchymal stromal cell (MSC) therapy is a promising treatment that allows for drug minimization in clinical kidney transplantation. While it is thought that MSCs rapidly go into apoptosis after infusion, clinical evidence for this is scarce since methods to detect cell death of infused cells in vivo are lacking. Cell-free DNA (cfDNA) has recently gained attention as a biomarker for cell death. Methods: In this study, we longitudinally measured cfDNA in plasma samples of the recipient, kidney donor, and allogeneic third-party MSC in the context of the Neptune study. cfDNA levels were measured at several time points before and after allogeneic MSC infusion in the 10 recipients who participated in the Neptune study. cfDNA ratios between the recipient, kidney graft, and MSC were determined. Results: We observed a peak in MSC-derived cfDNA 4 h after the first and second infusions, after which MSC-derived cfDNA became undetectable. Generally, kidney graft-derived cfDNA remained in the baseline-level range. Discussion: Our results support preclinical data that MSC are short-lived after infusion, also in a clinical in vivo setting, and are relevant for further research into the mechanism of action of MSC therapy.

Peripheral Blood Immune Cell Composition After Autologous MSC Infusion in Kidney Transplantation Recipients.

Tacrolimus is the backbone of immunosuppressive agents to prevent transplant rejection. Paradoxically, tacrolimus is nephrotoxic, causing irreversible tubulointerstitial damage. Therefore, infusion of mesenchymal stromal cells (MSC) 6 and 7 weeks post-transplantation was assessed to facilitate withdrawal of tacrolimus in the randomized phase II TRITON trial. Here, we performed detailed analysis of the peripheral blood immune composition using mass cytometry to assess potential effects of MSC therapy on the immune system. We developed two metal-conjugated antibody panels containing 40 antibodies each. PBMC samples from 21 MSC-treated patients and 13 controls, obtained pre-transplant and at 24 and 52 weeks post-transplantation, were analyzed. In the MSC group at 24 weeks, 17 CD4+ T cell clusters were increased of which 14 Th2-like clusters and three Th1/Th2-like clusters, as well as CD4+FoxP3+ Tregs. Additionally, five B cell clusters were increased, representing either class switched memory B cells or proliferating B cells. At 52 weeks, CCR7+CD38+ mature B cells were decreased. Finally, eight Tc1 (effector) memory cytotoxic T cell clusters were increased. Our work provides a comprehensive account of the peripheral blood immune cell composition in kidney transplant recipients after MSC therapy and tacrolimus withdrawal. These results may help improving therapeutic strategies using MSCs with the aim to reduce the use of calcineurin inhibitors. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02057965.

Urinary Kidney Injury Biomarkers Are Associated with Ischemia-Reperfusion Injury Severity in Kidney Allograft Recipients.

BACKGROUND: We explored the potential of emerging and conventional urinary kidney injury biomarkers in recipients of living donor (LD) or donation after circulatory death (DCD) kidney transplantation, patients with chronic kidney disease (CKD), and individuals from the general population. METHODS: Urine samples from kidney allograft recipients with mild (LD; n = 199) or severe (DCD; n = 71) ischemia-reperfusion injury (IRI) were analyzed for neutrophil gelatinase-associated lipocalin (NGAL), insulin-like growth factor-binding protein 7 (IGFBP7), tissue inhibitor of metalloproteinases 2 (TIMP2), kidney injury molecule-1 (KIM-1), chemokine C-X-C motif (CXCL9), solute carrier family 22 member 2 (SLC22A2), nephrin, and uromodulin (UMOD) by quantitative multiplex LC-MS/MS analysis. The fold-change in biomarker levels was determined in mild and severe IRI and in patients with CKD stage 1-2 (n = 127) or stage ≥3 (n = 132) in comparison to the general population (n = 1438). Relationships between the biomarkers and total protein, ß2-microglobulin (B2M), creatinine, and osmolality were assessed. RESULTS: NGAL, IGFBP7, TIMP2, KIM-1, CXCL9, and UMOD were quantifiable, whereas nephrin and SLC22A2 were below the limit of detection. Kidney injury biomarkers were increased up to 6.2-fold in allograft recipients with mild IRI and 8.3-fold in recipients with severe IRI, compared to the reference population, with the strongest response observed for NGAL and B2M. In CKD stage 1-2, B2M, NGAL, IGFBP7, TIMP2, KIM-1, UMOD, and CXCL9 were not altered, but in individuals with CKD stage ≥3, B2M, NGAL, and KIM-1 were increased up to 1.3-fold. IGFBP7, TIMP2, NGAL, and CXCL9 were strongly correlated (all r ≥ 0.8); correlations with B2M and TP were smaller (all r ≤ 0.6). CONCLUSIONS: IRI, but not stable CKD, was associated with increased urinary levels of kidney injury biomarkers determined by LC-MS/MS. Absolute and multiplexed protein quantitation by LC-MS/MS is an effective strategy for biomarker panel evaluation for translation toward the clinical laboratory.

Tacrolimus and Mycophenolic Acid Exposure Are Associated with Biopsy-Proven Acute Rejection: A Study to Provide Evidence for Longer-Term Target Ranges.

Evidence to define target ranges for tacrolimus (Tac) and mycophenolic acid (MPA) exposure after the first year of kidney transplantation is limited. We investigated the association of measurements at 1 year and repeated measurements of real-world Tac-trough levels (C0 ) and abbreviated area under the curve from zero to 12 hours (AUC0-12h ) of Tac and MPA with biopsy-proven acute rejection (BPAR) between years 1 and 3 post-transplant in 968 kidney transplant recipients (KTRs). Thirty-five (3.6%) out of 968 KTRs experienced BPAR. Both Tac-AUC0-12h (hazard ratio (HR): 0.39, 95% confidence interval (CI): 0.30-0.50, P < 0.001), Tac-C0 (HR: 0.46, 95% CI: 0.38-0.57, P < 0.001) and MPA-AUC0-12h at 1 year (HR: 0.80, 95% CI: 0.68-0.94, P = 0.006), as well as repeated measurements of Tac-C0 (HR: 0.70, 95% credibility interval (CrI): 0.61-0.82, P < 0.001), and of MPA-AUC0-12h (HR: 0.75, 95% CrI: 0.62-0.93, P < 0.001) were associated with BPAR. In our population, the recommended target range for Tac-AUC0-12h at 1 year would be 75-95 ng*hour/mL and a Tac-C0 5-7 ng/mL. The Tac-AUC0-12h predicted BPAR better than Tac-C0 and identified KTRs with over- or underexposure despite supposedly adequate Tac-C0 . We did not find evidence to recommend another target than the consensus range of 30-60 mg*hour/L for MPA-AUC0-12h after the first year of transplantation. To our knowledge, this is a first study on the simultaneous exposure of Tac and MPA at year 1 and subsequent BPAR up to year 3, which may help define the therapeutic target window for the longer term.

HLA-DQ eplet mismatch load may identify kidney transplant patients eligible for tacrolimus withdrawal without donor-specific antibody formation after mesenchymal stromal cell therapy.

Recently, the randomized phase-II Triton study demonstrated that mesenchymal stromal cell (MSC) therapy facilitated early tacrolimus withdrawal in living donor kidney transplant recipients. The current sub-study analyzed formation of de novo donor-specific HLA antibodies (dnDSA) in the context of the degree of HLA eplet mismatches. At the time of protocol biopsy at 6 months, 7/29 patients (24%) in the MSC group and 1/27 patient (3.7%) in the control group had developed dnDSA. In the MSC group, all dnDSA were anti-HLA-DQ; two patients had anti-DQ alone and five patients combined with anti-class I, HLA-DR or -DP. Despite excess dnDSA formation in the MSC-arm of the study, the evolution of eGFR (CKD-EPI) and proteinuria were comparable 2 years posttransplant. All dnDSA were complement-binding and three patients had antibody-mediated rejection in the protocol biopsy, but overall rejection episodes were not increased. Everolimus had to be discontinued in nine patients because of toxicity, and tacrolimus was reintroduced in six patients because of dnDSA formation. The HLA-DQ eplet mismatch load independently associated with dnDSA (adjusted hazard ratio = 1.07 per eplet mismatch, p = 0.008). A threshold of ≥11 HLA-DQ eplet mismatches predicted subsequent dnDSA in all 11 patients in the MSC group, but specificity was low (44%). Further research is warranted to explore HLA molecular mismatch load as a biomarker to guide personalized maintenance immunosuppression in kidney transplantation.

Cardiovascular Risk Following Conversion to Belatacept From a Calcineurin Inhibitor in Kidney Transplant Recipients: A Randomized Clinical Trial.

Rationale & Objective: In kidney transplant recipients (KTRs), a belatacept-based immunosuppressive regimen is associated with beneficial effects on cardiovascular (CV) risk factors compared with calcineurin inhibitor (CNI)-based regimens. Our objective was to compare the calculated CV risk between belatacept and CNI (predominantly tacrolimus) treatments using a validated model developed for KTRs. Study Design: Prospective, randomized, open-label, parallel-group, investigator-initiated, international multicenter trial. Setting & Participants: KTRs aged 18-80 years with a stable graft function (estimated glomerular filtration rate > 20 mL/min/1.73 m2), 3-60 months after transplantation, treated with tacrolimus or cyclosporine A, were eligible for inclusion. Intervention: Continuation with a CNI-based regimen or switch to belatacept for 12 months. Outcomes: Comparison of the change in the estimated 7-year risk of major adverse CV events and all-cause mortality, changes in traditional markers of CV health, as well as measures of arterial stiffness. Results: Among the 105 KTRs randomized, we found no differences between the treatment groups in the predicted risk for major adverse CV events or mortality. Diastolic blood pressure, measured both centrally by using a SphygmoCor device and peripherally, was lower after the belatacept treatment than after the CNI treatment. The mean changes in traditional cardiovascular (CV) risk factors, including kidney transplant function, were otherwise similar in both the treatment groups. The belatacept group had 4 acute rejection episodes; 2 were severe rejections, of which 1 led to graft loss. Limitations: The heterogeneous baseline estimated glomerular filtration rate and time from transplantation to trial enrollment in the participants. A limited study duration of 1 year. Conclusions: We found no effects on the calculated CV risk by switching to the belatacept treatment. Participants in the belatacept group had not only lower central and peripheral diastolic blood pressure but also a higher rejection rate. Funding: The trial has received a financial grant from Bristol-Myers Squibb. Trial Registration: EudraCT no. 2013-001178-20.

HLA expression as a risk factor for metastases of cutaneous squamous-cell carcinoma in organ- transplant recipients.

BACKGROUND: Solid organ-transplant recipients (SOTR) have an increased risk of cutaneous squamous-cell carcinoma (cSCC), metastasis and death from cSCC. In immunocompetent patients with mucosal SCC, downregulation of HLA class I is associated with poor prognosis. Since the degree of HLA expression on tumor cells could play a role in immunogenicity and pathophysiology of cSCC metastasis, we hypothesized that decreased HLA expression is associated with an increased risk of metastasis. METHODS: We compared HLA expression between primary metastasized cSCCs, their metastases, and non-metastasized cSCCs from the same patients. Samples were stained for HLA-A, HLA-B/-C and quantified by calculating the difference in immunoreactivity score (IRS) of the primary cSCC compared with all non-metastasized cSCCs. RESULTS: The mean IRS score for HLA-B/C expression was 2.07 point higher in metastasized compared to non-metastasized cSCCs (p = 0.065, 95 % CI -0.18-4.32). 83.3 % of the primary metastasized cSCCs had an IRS score of 4 or higher, compared to 42.9 % in non-metastasized cSCCs. Moderately to poorly differentiated cSCCs had more HLA class I expression compared to well-differentiated cSCCs. CONCLUSION: Contrary to immunocompetent patients, HLA-B/C expression tends to be upregulated in metastasized cSCC compared to non-metastasized cSCC in SOTR, suggesting that different tumor escape mechanisms play a role in SOTR compared to immunocompetent patients.

Left Atrial Structural and Functional Response in Kidney Transplant Recipients Treated With Mesenchymal Stromal Cell Therapy and Early Tacrolimus Withdrawal.

BACKGROUND: Autologous bone marrow-derived mesenchymal stromal cell (MSC) therapy and withdrawal of calcineurin inhibitors (CNIs) has been shown to improve systemic blood pressure control and left ventricular hypertrophy regression in kidney transplant recipients. In the current subanalysis, we aimed to evaluate the impact of this novel immunosuppressive regimen on the longitudinal changes of left atrial (LA) structure and function after kidney transplantation. METHODS: Kidney transplant recipients randomized to MSC therapy-infused at weeks 6 and 7 after transplantation, with complete discontinuation at week 8 of tacrolimus (MSC group)-or standard tacrolimus dose (control group) were evaluated with transthoracic echocardiography at weeks 4 and 24 after kidney transplantation. The changes in echocardiographic parameters were compared between the randomization arms using an analysis of covariance model adjusted for baseline variable. RESULTS: Fifty-four participants (MSC therapy = 27; tacrolimus therapy = 27) were included. There was no significant interaction between the allocated treatment and the changes of indexed maximal LA volume (LAVImax) over the study period. Conversely, between 4 and 24 weeks post-transplantation, an increase in indexed minimal LA volume (LAVImin) was observed in control subjects, while it remained unchanged in the MSC group, leading to a significant difference between groups (P = .021). Additionally, patients treated with MSC therapy showed a benefit in LA function, assessed by a significant interaction between changes in LA emptying fraction and LA reservoir strain and the randomization arm (P = .012 and P = .027, respectively). CONCLUSIONS: The combination of MSC therapy and CNIs withdrawal prevents progressive LA dilation and dysfunction in the first 6 months after kidney transplantation. LAVImin and LA reservoir strain may be more sensitive markers of LA reverse remodeling, compared with LAVImax.

Reference intervals of urinary kidney injury biomarkers for middle-aged men and women determined by quantitative protein mass spectrometry.

BACKGROUND AND AIMS: There is an ongoing need to recognize early kidney injury and its progression in structural chronic pathologies. The proteins neutrophil-gelatinase-associated lipocalin (NGAL), insulin-like growth factor-binding protein 7 (IGFBP7), tissue inhibitor of metalloproteinases 2 (TIMP2), kidney injury molecule-1 (KIM-1), C-X-C motif chemokine 9 (CXCL9), transforming growth factor-beta 1 (TGF-ß1), solute carrier family 22 member 2 (SLC22A2), nephrin, cubilin, and uromodulin (UMOD) have been proposed as early kidney injury biomarkers. To guide clinical interpretation, their urinary concentrations should be accompanied by reference intervals, which we here establish in a representative Dutch middle-aged population. MATERIALS AND METHODS: The 24 h urine samples from 1443 Caucasian middle-aged men and women were analyzed for the biomarkers by quantitative LC-MS/MS. Biomarker excretion per 24 h were calculated, and urine creatinine and osmolality were measured for dilution normalization. This population was characterized by demographic and anthropometric parameters, comorbid conditions, and conventional kidney function measures. RESULTS: NGAL, IGFBP7, TIMP2, KIM-1, and UMOD could be quantified in this population, whereas nephrin, SLC22A2, and CXCL9 were below their detection limits. Urine creatinine and osmolality were correlated to urine volume (r = -0.71; -0.74) and to IGFBP7 (r = 0.73; 0.71) and TIMP2 (r = 0.71; 0.69). Crude and normalized biomarker concentrations were affected by sex, but not by age, body mass index, smoking, kidney function, or common comorbid conditions. The reference intervals (men; women) were 18-108; 21-131 pmol IGFBP7/mmol creatinine, 1-63; 4-224 pmol NGAL/mmol creatinine, 7-48; 7-59 pmol TIMP2/mmol creatinine, <1-9; <1-12 pmol KIM-1/mmol creatinine, and 0.1-1.2; 0.1-1.7 mg UMOD/mmol creatinine. CONCLUSION: We present dilution-normalized and sex-stratified urinary reference intervals of kidney injury biomarkers in a middle-aged Caucasian population.

Multiplex LC-MS/MS Testing for Early Detection of Kidney Injury: A Next-Generation Alternative to Conventional Immunoassays?

BACKGROUND: LC-MS/MS has enabled the translation of many novel biomarkers to the clinical laboratory, but its potential for measurement of urinary proteins is still unexplored. In this study we examined the correlation and agreement between immunoassay and LC-MS/MS in the quantitation of kidney injury biomarkers and evaluated the application of technical LC-MS/MS meta-data assessment to ensure test result validity. METHODS: NGAL, IGFBP7, TIMP2, and KIM-1 were quantified in 345 urine samples with one multiplex lab-developed test that combines immunocapture with mass spectrometry read-out and 4 singleplex sandwich-type immunoassays. Assay performance and imprecision were monitored by 2 urine-based quality controls. Ion ratios, signal intensity, and retention time were monitored over all study samples. RESULTS: The LC-MS/MS retention time drift was ≤1.2%, ion ratios were within 20% of the target values at concentrations of >100 pmol/L, and peptides originating from the same protein were in agreement (slopes between 1.03 and 1.41). The interassay CV was between 9.3% and 19.1% for LC-MS/MS analysis and between 4.2% and 10.9% for immunoassay. Direct LC-MS/MS analysis was correlated with immunoassay in the quantitation of NGAL (r = 0.93; range: 0.01-37 nmol/L), IGFBP7 (r = 0.80; range: 0.01-2.6 nmol/L), TIMP2 (r = 0.85; range: 0.01-6.3 nmol/L), and KIM-1 (r = 0.70; range 0.01-0.4 nmol/L), but the analytical methodologies differed in measurands and calibration strategies. CONCLUSIONS: LC-MS/MS is explored as a next-generation technology for multiplex urinary protein measurement. It has great potential to overcome nonselectivity and lack of standardization because of its capability of directly measuring well-defined molecular proteins.

Cardiovascular Effects of Autologous Bone Marrow-Derived Mesenchymal Stromal Cell Therapy With Early Tacrolimus Withdrawal in Renal Transplant Recipients: An Analysis of the Randomized TRITON Study.

Background After renal transplantation, there is a need of immunosuppressive regimens that effectively prevent allograft rejection while minimizing cardiovascular complications. This substudy of the TRITON trial evaluated the cardiovascular effects of autologous bone marrow-derived mesenchymal stromal cells (MSCs) in renal transplant recipients. Methods and Results Renal transplant recipients were randomized to MSC therapy, infused at weeks 6 and 7 after transplantation, with withdrawal at week 8 of tacrolimus or standard tacrolimus dose. Fifty-four patients (MSC group=27; control group=27) underwent transthoracic echocardiography at weeks 4 and 24 after transplantation and were included in this substudy. Changes in clinical and echocardiographic variables were compared. The MSC group showed a benefit in blood pressure control, assessed by a significant interaction between changes in diastolic blood pressure and the treatment group (P=0.005), and a higher proportion of patients achieving the predefined blood pressure target of <140/90 mm Hg compared with the control group (59.3% versus 29.6%, P=0.03). A significant reduction in left ventricular mass index was observed in the MSC group, whereas there were no changes in the control group (P=0.002). The proportion of patients with left ventricular hypertrophy decreased at 24 weeks in the MSC group (33.3% versus 70.4%, P=0.006), whereas no changes were noted in the control group (63.0% versus 48.1%, P=0.29). Additionally, MSC therapy prevented progressive left ventricular diastolic dysfunction, as demonstrated by changes in mitral deceleration time and tricuspid regurgitant jet velocity. Conclusions MSC strategy is associated with improved blood pressure control, regression of left ventricular hypertrophy, and prevention of progressive diastolic dysfunction at 24 weeks after transplantation. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03398681.

Development and Provisional Validation of a Multiplex LC-MRM-MS Test for Timely Kidney Injury Detection in Urine.

Kidney injury is a complication frequently encountered in hospitalized patients. Early detection of kidney injury prior to loss of renal function is an unmet clinical need that should be targeted by a protein-based biomarker panel. In this study, we aim to quantitate urinary kidney injury biomarkers at the picomolar to nanomolar level by liquid chromatography coupled to tandem mass spectrometry in multiple reaction monitoring mode (LC-MRM-MS). Proteins were immunocaptured from urinary samples, denatured, reduced, alkylated, and digested into peptides before LC-MRM-MS analysis. Stable-isotope-labeled peptides functioned as internal standards, and biomarker concentrations were attained by an external calibration strategy. The method was evaluated for selectivity, carryover, matrix effects, linearity, and imprecision. The LC-MRM-MS method enabled the quantitation of KIM-1, NGAL, TIMP2, IGFBP7, CXCL9, nephrin, and SLC22A2 and the detection of TGF-ß1, cubilin, and uromodulin. Two to three peptides were included per protein, and three transitions were monitored per peptide for analytical selectivity. The analytical carryover was <1%, and minimal urine matrix effects were observed by combining immunocapture and targeted LC-MRM-MS analysis. The average total CV of all quantifier peptides was 26%. The linear measurement range was determined per measurand and found to be 0.05-30 nmol/L. The targeted MS-based method enables the multiplex quantitation of low-abundance urinary kidney injury biomarkers for future clinical evaluation.

Conversion from Calcineurin Inhibitor- to Belatacept-Based Maintenance Immunosuppression in Renal Transplant Recipients: A Randomized Phase 3b Trial.

BACKGROUND: Calcineurin inhibitors (CNIs) are standard of care after kidney transplantation, but they are associated with nephrotoxicity and reduced long-term graft survival. Belatacept, a selective T cell costimulation blocker, is approved for the prophylaxis of kidney transplant rejection. This phase 3 trial evaluated the efficacy and safety of conversion from CNI-based to belatacept-based maintenance immunosuppression in kidney transplant recipients. METHODS: Stable adult kidney transplant recipients 6-60 months post-transplantation under CNI-based immunosuppression were randomized (1:1) to switch to belatacept or continue treatment with their established CNI. The primary end point was the percentage of patients surviving with a functioning graft at 24 months. RESULTS: Overall, 446 renal transplant recipients were randomized to belatacept conversion ( n =223) or CNI continuation ( n =223). The 24-month rates of survival with graft function were 98% and 97% in the belatacept and CNI groups, respectively (adjusted difference, 0.8; 95.1% CI, -2.1 to 3.7). In the belatacept conversion versus CNI continuation groups, 8% versus 4% of patients experienced biopsy-proven acute rejection (BPAR), respectively, and 1% versus 7% developed de novo donor-specific antibodies (dnDSAs), respectively. The 24-month eGFR was higher with belatacept (55.5 versus 48.5 ml/min per 1.73 m 2 with CNI). Both groups had similar rates of serious adverse events, infections, and discontinuations, with no unexpected adverse events. One patient in the belatacept group had post-transplant lymphoproliferative disorder. CONCLUSIONS: Switching stable renal transplant recipients from CNI-based to belatacept-based immunosuppression was associated with a similar rate of death or graft loss, improved renal function, and a numerically higher BPAR rate but a lower incidence of dnDSA.Clinical Trial registry name and registration number: A Study in Maintenance Kidney Transplant Recipients Following Conversion to Nulojix® (Belatacept)-Based, NCT01820572.

Autologous bone marrow-derived mesenchymal stromal cell therapy with early tacrolimus withdrawal: The randomized prospective, single-center, open-label TRITON study.

After renal transplantation, there is a need for immunosuppressive regimens which effectively prevent allograft rejection, while preserving renal function and minimizing side effects. From this perspective, mesenchymal stromal cell (MSC) therapy is of interest. In this randomized prospective, single-center, open-label trial, we compared MSCs infused 6 and 7 weeks after renal transplantation and early tacrolimus withdrawal with a control tacrolimus group. Primary end point was quantitative evaluation of interstitial fibrosis in protocol biopsies at 4 and 24 weeks posttransplant. Secondary end points included acute rejection, graft loss, death, renal function, adverse events, and immunological responses. Seventy patients were randomly assigned of which 57 patients were included in the final analysis (29 MSC; 28 controls). Quantitative progression of fibrosis failed to show benefit in the MSC group and GFR remained stable in both groups. One acute rejection was documented (MSC group), while subclinical rejection in week 24 protocol biopsies occurred in seven patients (four MSC; three controls). In the MSC group, regulatory T cell numbers were significantly higher compared to controls (p = .014, week 24). In conclusion, early tacrolimus withdrawal with MSC therapy was safe and feasible without increased rejection and with preserved renal function. MSC therapy is a potentially useful approach after renal transplantation.

The predictive value of TIMP-2 and IGFBP7 for kidney failure and 30-day mortality after elective cardiac surgery.

Acute kidney injury (AKI) is an important risk factor for chronic kidney disease, renal replacement therapy (RRT), and mortality. However, predicting AKI with currently available markers remains problematic. We assessed the predictive value of urinary tissue inhibitor of metalloprotease-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) regarding the need for RRT, and 30-day mortality, in elective cardiac surgery patients. In 344 elective cardiac surgery patients, we measured urinary TIMP-2 and IGFBP7 and serum creatinine at baseline and directly after surgery. Discrimination of both urinary biomarkers was assessed by the C-statistic. Model improvement for each biomarker when added to a basic model containing serum creatinine and duration of surgery was tested by the net-reclassification index (cf-NRI) and integrated discrimination index (IDI). At baseline, mean age was 66 years and 67% were men. Of all patients, 22 required RRT following surgery. IGFBP7 pre- and post-surgery and change in TIMP-2 during surgery predicted RRT with a C-statistic of about 0.80. However, a simple model including baseline serum creatinine and duration of surgery had a C-statistic of 0.92, which was improved to 0.93 upon addition of post-surgery TIMP-2 or IGFBP7, with statistically significant cf-NRIs but non-significant IDIs. Post-surgery TIMP-2 and IGFBP predicted 30-day mortality, with C-statistics of 0.74 and 0.80. In conclusion, in elective cardiac surgery patients, pre- and peri-operative clinical variables were highly discriminating about which patients required RRT after surgery. Nonetheless, in elective cardiac surgery patients, urinary TIMP-2 and IGFBP7 improved prediction of RRT and 30-day mortality post-surgery.

Biopsy-Controlled Non-Invasive Quantification of Collagen Type VI in Kidney Transplant Recipients: A Post-Hoc Analysis of the MECANO Trial.

The PRO-C6 assay, a reflection of collagen type VI synthesis, has been proposed as a non-invasive early biomarker of kidney fibrosis. We aimed to investigate cross-sectional and longitudinal associations between plasma and urine PRO-C6 and proven histological changes after kidney transplantation. The current study is a post-hoc analysis of 94 participants of the MECANO trial, a 24-month prospective, multicenter, open-label, randomized, controlled trial aimed at comparing everolimus-based vs. cyclosporine-based immunosuppression. PRO-C6 was measured in plasma and urine samples collected 6 and 24 months post-transplantation. Fibrosis was evaluated in biopsies collected at the same time points by Banff interstitial fibrosis/tubular atrophy (IF/TA) scoring and collagen staining (Picro Sirius Red; PSR); inflammation was evaluated by the tubulo-interstitial inflammation score (ti-score). Linear regression analyses were performed. Six-month plasma PRO-C6 was cross-sectionally associated with IF/TA score (Std. ß = 0.34), and prospectively with 24-month IF/TA score and ti-score (Std. ß = 0.24 and 0.23, respectively) (p < 0.05 for all). No significant associations were found between urine PRO-C6 and any of the biopsy findings. Fibrotic changes and urine PRO-C6 behaved differentially over time according to immunosuppressive therapy. These results are a first step towards non-invasive fibrosis detection after kidney transplantation by means of collagen VI synthesis measurement, and further research is required.

Efficacy and safety of selective decontamination of the digestive tract (SDD) to prevent recurrent hepatic cyst infections in polycystic liver disease: a retrospective case series.

BACKGROUND: Hepatic cyst infection is a complication of polycystic liver disease (PLD) that causes substantial morbidity. Repetitive infection is frequent and is increasingly difficult to treat. As translocated gut bacteria are considered the cause, we hypothesize that selective decontamination of the digestive tract (SDD) reduces recurrence of hepatic cyst infection. METHODS: We performed a retrospective, observational study in two referral centres. All patients with PLD treated with SDD for hepatic cyst infection were included. Efficacy was determined by calculating the infection incidence (hepatic cyst infections per month) before and during SDD therapy. Adverse events were scored according to the Common Terminology Criteria for Adverse Events (CTCAE). RESULTS: We identified eight patients who received SDD (88% female, 88% polycystic kidney disease). The median age was 65 years (IQR: 51-74 years). SDD lowered the median incidence from 0.09 episodes per month (IQR: 0.06-0.25 episodes per month) to 0.01 episodes per month (IQR: 0.00-0.05 episodes per month) (P = 0.12). Discontinuation of SDD led to rapid recurrence of cyst infection (71% within 6 weeks). SDD consisted of polymyxins with/without aminoglycosides. The median SDD treatment duration was 20 months (range: 3-89 months). Six patients (75%) developed adverse events [CTCAE Grade 1 (gastrointestinal: n = 3) or Grade 3 (ototoxicity: n = 1; fungal infection: n = 1)], mostly attributable to aminoglycosides; one patient developed polymyxin E resistance. CONCLUSIONS: SDD prophylaxis provides a novel strategy for limiting recurrent hepatic cyst infection in PLD patients. However, adverse events are frequent and curtail its use. As most were attributable to aminoglycosides, polymyxin E is considered the preferred therapy.