Correlation of Donor-derived Cell-free DNA With Histology and Molecular Diagnoses of Kidney Transplant Biopsies.

BACKGROUND: Circulating donor-derived cell-free DNA (cfDNA), a minimally invasive diagnostic tool for kidney transplant rejection, was validated using traditional histology. The molecular microscope diagnostic system (MMDx) tissue gene expression platform may provide increased precision to traditional histology. METHODS: In this single-center prospective study of 208 biopsies (median = 5.8 mo) posttransplant, we report on the calibration of cfDNA with simultaneous biopsy assessments using MMDx and histology by area under the curve (AUC) analyses for optimal criterion, as well as for, previously published cfDNA cutoffs ≤ 0.21% to "rule-out" rejection and ≥1% to "rule-in" rejection. RESULTS: There were significant discrepancies between histology and MMDx, with MMDx identifying more antibody-mediated rejection (65; 31%) than histology (43; 21%); the opposite was true for T cell-mediated rejection [TCMR; histology: 27 (13%) versus MMDx: 13 (6%)]. Most of the TCMR discrepancies were seen for histologic borderline/1A TCMR. AUC for cfDNA and prediction of rejection were slightly better with MMDx (AUC = 0.80; 95% CI: 0.74-0.86) versus histology (AUC = 0.75; 95% CI: 0.69-0.81). A cfDNA ≤ 0.21% had similar sensitivity (~91%) to "rule-out" rejection by histology and MMDx. Specificity was slightly higher with MMDx (92%) compared with histology (85%) to "rule-in" rejection using cfDNA criterion ≥1%. Strong positive quantitative correlations were observed between cfDNA scores and molecular acute kidney injury for both "rejection" and "nonrejection" biopsies. CONCLUSIONS: Molecular diagnostics using tissue gene expression and blood-based donor-derived cell-free DNA may add precision to some cases of traditional histology. The positive correlation of cfDNA with molecular acute kidney injury suggests a dose-dependent association with tissue injury irrespective of rejection characteristics.

Impact of belatacept conversion on kidney transplant function, histology, and gene expression - a single-center study.

Prior studies on belatacept conversion from calcineurin inhibitor (CNI) have been limited by an absence of postconversion surveillance biopsies that could underestimate subclinical rejection, or a case-controlled design. A total of 53 adult patients with allograft dysfunction underwent belatacept conversion (median: 6 months) post-transplant. At a median follow-up = 2.5 years, patient survival was 94% with a death-censored graft survival of 85%. Seven (13%) patients had acute rejection (including 3 subclinical) at median 6 months postconversion. Overall, eGFR improved (P = <0.001) from baseline = 31±15 to 40.2 ± 17.6 ml/min/1.73m2 by 6 months postconversion, but then stayed stable. This improvement was also observed (P < 0.001) in comparison with a propensity matched control cohort on CNI, where eGFR stayed stable (mean ~ 32ml/min/1.72m2 ) over 2-year follow-up. Patients converted < 6 months post-transplant were more likely to have a long-term improvement in kidney function. Paired gene expression analysis of 30 (of 53) consecutive pre- and postconversion surveillance biopsies did not reveal changes in inflammation/acute injury; although atrophy-fibrosis score worsened (mean = 0.28 to 0.44; P = 0.005). Thus, improvement in renal function with belatacept conversion occurred early and then sustained in comparison with controls where renal function remained unchanged overtime. We were unable to show molecular signals that could be related to CNI administration and regressed after withdrawal.

Ultra-short duration direct acting antiviral prophylaxis to prevent virus transmission from hepatitis C viremic donors to hepatitis C negative kidney transplant recipients.

We conducted an adaptive design single-center pilot trial between October 2017 and November 2018 to determine the safety and efficacy of ultra-short-term perioperative pangenotypic direct acting antiviral (DAA) prophylaxis for deceased hepatitis C virus (HCV)-nucleic acid test (NAT) positive donors to HCV negative kidney recipients (D+/R-). In Group 1, 10 patients received one dose of SOF/VEL (sofusbuvir/velpatasvir) pretransplant and one dose on posttransplant Day 1. In Group 2A (N = 15) and the posttrial validation (Group 2B; N = 25) phase, patients received two additional SOF/VEL doses (total 4) on Days 2 and 3 posttransplant. Development of posttransplant HCV transmission triggered 12-week DAA therapy. For available donor samples (N = 27), median donor viral load was 1.37E + 06 IU/mL (genotype [GT]1a: 70%; GT2: 7%; GT3: 23%). Overall viral transmission rate was 12% (6/50; Group 1:30% [3/10]; Group 2A:13% [2/15]; Group 2B:4% [1/25]). For the 6 viremic patients, 5 (83%) achieved sustained virologic response (3 with first-line DAA therapy; and two after retreatment with second-line DAA). At a median follow-up of 8 months posttransplant, overall patient and allograft survivals were 98%, respectively. The 4-day strategy reduced viral transmission to 7.5% (3/40; 95% confidence interval [CI]: 1.8%-20.5%) and could result in avoidance of prolonged posttransplant DAA therapy for most D+/R - transplants.

Successful kidney transplantation in a patient with congenital thrombotic thrombocytopenic purpura (Upshaw-Schulman syndrome).

BACKGROUND: Congenital thrombotic thrombocytopenic purpura (TTP) may not be recognized until organ failure related to the microvascular thrombosis occurs. Kidney failure may be the initial presenting clinical feature. Kidney transplantation has been contraindicated because of the assumption that the continuing microvascular thrombosis will cause inevitable graft failure. CASE REPORT: We report a 48-year-old nulliparous woman who presented with end-stage kidney disease that was attributed to hypertension. Her past history included a thromboembolic stroke at age 32, for which she was placed on permanent anticoagulation. Immediately after living unrelated-donor kidney transplant, she developed severe hemolysis and acute decline in urine output for which she received red blood cell and platelet transfusions and an infusion of eculizumab (1200 mg). She promptly responded and was discharged on her fifth postoperative day with a serum creatinine level of 1.0 mg/dL. Two weeks later, thrombocytopenia and hemolysis recurred. By this time, undetectable ADAMTS13 activity (<5%) with no demonstrable inhibitor had been reported. She responded rapidly to plasma infusions. Genetic analysis confirmed the diagnosis of congenital TTP, documenting known pathogenic mutations in each of the ADAMTS13 genes. She continued to receive twice-monthly infusions for 4 months. Surveillance kidney biopsies at 6 and 12 months posttransplant demonstrated no evidence of thrombotic microangiopathy or graft rejection. After 2 years of follow-up her creatinine remains stable at 1.0 mg/dL (estimated glomerular filtration rate, 65 mL/min/1.73 m2 ). CONCLUSION: Our experience suggests that kidney transplantation may be an appropriate management for carefully selected patients with congenital TTP who develop end-stage renal disease.

Long-term outcomes and transmission rates in hepatitis C virus-positive donor to hepatitis C virus-negative kidney transplant recipients: Analysis of United States national data.

The use of kidneys from hepatitis C virus (HCV)-positive (D+) deceased donors for HCV-negative recipients (R-) might increase the donor pool. We analyzed the national Organ Procurement and Transplant Network (OPTN) registry from 1994 to 2014 to compare the outcomes of HCV D+/R- (n = 421) to propensity-matched HCV-negative donor (D-)/R- kidney transplants, as well as with waitlisted patients who never received a transplant, in a 1:5 ratio (n = 2105, per matched group). Both 5-year graft survival (44% vs 66%; P < .001) and patient survival (57% vs 79%; P < .001) were inferior for D+/R- group compared to D-/R-. Nevertheless, 5-year patient survival from the time of wait listing was superior for D+/R- when compared to waitlisted controls (68% vs 43%; P < .001). Of the 126 D+/R- with available post-transplant HCV testing, HCV seroconversion was confirmed in 62 (49%), likely donor-derived. Five-year outcomes were similar between D+/R- that seroconverted vs D+/R- that did not (n = 64). Our analysis shows inferior outcomes for D+/R- patients although detailed data on pretransplant risk factors was not available. Limited data suggest that HCV transmission occurred in half of HCV D+/R- patients, although this might not have been the primary factor contributing to the poor observed outcomes.

Outcomes of kidney transplants and risk of infection transmission from increased infectious risk donors.

Concern over transmission of viral infections has been reported to result in higher discard rates of high infectious risk kidneys (HIR) although data on actual viral transmission rates are lacking. At our center, we performed 89 HIR and 533 non-HIR kidney transplants (KTs) between 2004 and 2011. Follow-up screening labs in recipients of HIR kidneys tested for human immunodeficiency virus, hepatitis C virus, and hepatitis B virus did not reveal any cases of viral transmission over median follow-up of 4.3 years. Patient and graft outcomes were similar at 5 years between HIR and non-HIR KTs. An updated analysis of the Organ Procurement and Transplant Network (OPTN) registry of deceased-donor kidney transplants between 2008 and 2012 included 57 526 transplants was performed. Retrospective calculation of KDRI (kidney donor risk index) differed (P<.001) between all groups with median KDRI of 0.99 for HIR kidneys, 1.07 for non-HIR standard criteria donor kidneys, and 1.81 for non-HIR expanded criteria donor (ECD) kidneys. This was reflected in the significantly improved 5-year graft survival for HIR KTs when compared with non-HIR ECD KTs (84% vs 78%; P<.001). Our data can guide counseling of KT candidates about the safety and benefits of HIR kidneys.

Pre-transplant phospholipase A2 receptor autoantibody concentration is associated with clinically significant recurrence of membranous nephropathy post-kidney transplantation.

Previous studies that have assessed the association of pre-transplant antiphospholipase A2 receptor autoantibody (PLA2R-Ab) concentration with a recurrence of membranous nephropathy (rMN) post-kidney transplant have yielded variable results. We tested 16 consecutive transplant patients with a history of iMN for pre-transplant PLA2R-Ab. Enzyme-linked immunosorbent assay titers (Euroimmun, NJ, USA) >14 RU/mL were considered positive. A receiver operating characteristic (ROC) analysis was performed after combining data from Quintana et al. (n = 21; Transplantation February 2015) to determine a PLA2R-Ab concentration which could predict rMN. Six of 16 (37%) patients had biopsy-proven rMN at a median of 3.2 yr post-transplant. Of these, five of six (83%) had a positive PLA2R-Ab pre-transplant with a median of 82 RU/mL (range = 31-1500). The only patient who had rMN with negative PLA2R-Ab was later diagnosed with B-cell lymphoma. One hundred percent (n = 10) of patients with no evidence of rMN (median follow-up = five yr) had negative pre-transplant PLA2R-Ab. In a combined ROC analysis (n = 37), a pre-transplant PLA2R-Ab > 29 RU/mL predicted rMN with a sensitivity of 85% and a specificity of 92%. Pre-transplant PLA2R-Ab could be a useful tool for the prediction of rMN. Patients with rMN in the absence of PLA2R-Ab should be screened for occult malignancy and/or alternate antigens.

Post-transplant Desensitization for Deceased Donor Kidney Transplant Recipients: A Single Center Experience.

The highly-sensitized kidney transplant candidate with no available living donors remains at a major disadvantage with decreased access and worse outcomes post-transplant. We have previously reported our initial data on both pre-transplant and post-transplant desensitization. We observed only a modest decline in unacceptable antigens with pretransplant intravenous immunoglobin (IVIG) and rituximab. Due to these observations, we have focused on a peri-operative post-transplant desensitization protocol in our program. Beginning in 2006, we implemented a simple point-based algorithm [variables included: panel reactive antibody (PRA) status; flow cytometric crossmatch (FCXM); and delayed graft function] to identify kidney transplant recipients who would undergo peri-operative plasmapheresis/IVIG to abrogate preformed antibody-mediated allograft rejection (AMR). Our previous results suggested acceptable 5-year outcomes. Here, in an expanded population (N=66), we report an overall death-censored graft survival of 73% at a mean follow-up of 8.5 years post-transplant. Our patients were largely African American (85%) and regrafts (39%), with a median PRA of 88%, and a mean T- and B-FCXM of 97 mean channel shifts (MCS) and 117 MCS, respectively. Although acute AMR rates were acceptable (12%), 22% of patients developed chronic AMR. A pre-transplant T-cell FCXM of > 200 MCS (p=0.02) or presence of donor specific antibodies (DSA) at most recent follow-up (p=0.02) were associated with graft loss. Current studies with revised protocols utilizing additional DSA information, surveillance biopsies, and proteasome inhibition are ongoing.

The urine microRNA profile may help monitor post-transplant renal graft function.

Noninvasive, cost-effective biomarkers that allow accurate monitoring of graft function are needed in kidney transplantation. Since microRNAs (miRNAs) have emerged as promising disease biomarkers, we sought to establish an miRNA signature in urinary cell pellets comparing kidney transplant patients diagnosed with chronic allograft dysfunction (CAD) with interstitial fibrosis and tubular atrophy and those recipients with normal graft function. Overall, we evaluated 191 samples from 125 deceased donor primary kidney transplant recipients in the discovery, initial validation, and the longitudinal validation studies for noninvasive monitoring of graft function. Of 1733 mature miRNAs studied using microarrays, 22 were found to be differentially expressed between groups. Ontology and pathway analyses showed inflammation as the principal biological function associated with these miRNAs. Twelve selected miRNAs were longitudinally evaluated in urine samples of an independent set of 66 patients, at two time points after kidney transplant. A subset of these miRNAs was found to be differentially expressed between groups early after kidney transplant before histological allograft injury was evident. Thus, a panel of urine miRNAs was identified as potential biomarkers for monitoring graft function and anticipating progression to CAD in kidney transplant patients.

Identification of biomarkers to assess organ quality and predict posttransplantation outcomes.

UNLABELLED: The increased disparity between organ supply and need has led to the use of extended criteria donors and donation after cardiac death donors with other comorbidities. METHODS: We have examined the preimplantation transcriptome of 112 kidney transplant recipient samples from 100 deceased-donor kidneys by microarray profiling. Subject groups were segregated based on estimated glomerular filtration rate (eGFR) at 1 month after transplantation: the GFR-high group (n=74) included patients with eGFR 45 mL/min per 1.73 m(2), whereas the GFR-low group (n=35) included patients with eGFR 45 mL/min or less per 1.73 m(2). RESULTS: Gene expression profiling identified higher expression of 160 probe sets (140 genes) in the GFR-low group, whereas expression of 37 probe sets (33 genes) was higher in the GFR-high group (P<0.01, false discovery rate <0.2). Four genes (CCL5, CXCR4, ITGB2, and EGF) were selected based on fold change and P value and further validated using an independent set of samples. A random forest analysis identified three of these genes (CCL5, CXCR4, and ITGB2) as important predictors of graft function after transplantation. CONCLUSIONS: Inclusion of pretransplantation molecular gene expression profiles in donor quality assessment systems may provide the necessary information for better donor organ selection and function prediction. These biomarkers would further allow a more objective and complete assessment of procured renal allografts at pretransplantation time.

Reduced expression of inflammatory genes in deceased donor kidneys undergoing pulsatile pump preservation.

BACKGROUND: The use of expanded criteria donor kidneys (ECD) had been associated with worse outcomes. Whole gene expression of pre-implantation allograft biopsies from deceased donor kidneys (DDKs) was evaluated to compare the effect of pulsatile pump preservation (PPP) vs. cold storage preservation (CSP) on standard and ECD kidneys. METHODOLOGY/PRINCIPAL FINDINGS: 99 pre-implantation DDK biopsies were studied using gene expression with GeneChips. Kidneys transplant recipients were followed post transplantation for 35.8 months (range = 24-62). The PPP group included 60 biopsies (cold ischemia time (CIT) = 1,367+/-509 minutes) and the CSP group included 39 biopsies (CIT = 1,022+/-485 minutes) (P<0.001). Donor age (42.0±14.6 vs. 34.1±14.2 years, P = 0.009) and the percentage of ECD kidneys (PPP = 35% vs. CSP = 12.8%, P = 0.012) were significantly different between groups. A two-sample t-test was performed, and probe sets having a P<0.001 were considered significant. Probe set level linear models were fit using cold ischemia time and CSP/PPP as independent variables to determine significant probe sets (P<0.001) between groups after adjusting for cold ischemia time. Thus, 43 significant genes were identified (P<0.001). Over-expression of genes associated with inflammation (CD86, CD209, CLEC4, EGFR2, TFF3, among others) was observed in the CSP group. Cell-to-cell signaling and interaction, and antigen presentation were the most important pathways with genes significantly over-expressed in CSP kidneys. When the analysis was restricted to ECD kidneys, genes involved in inflammation were also differentially up-regulated in ECD kidneys undergoing CSP. However, graft survival at the end of the study was similar between groups (P = 0.2). Moreover, the incidence of delayed graft function was not significant between groups. CONCLUSIONS/SIGNIFICANCE: Inflammation was the most important up-regulated pattern associated with pre-implantation biopsies undergoing CSP even when the PPP group has a larger number of ECD kidneys. No significant difference was observed in delayed graft function incidence and graft function post-transplantation. These findings support the use of PPP in ECD donor kidneys.

Graft-versus-host disease after solid organ transplantation: a single center experience and review of literature.

BACKGROUND: Graft-versus-host disease (GVHD) is an uncommon cause of morbidity and mortality after solid organ transplantation that is most likely under-diagnosed. We describe our single center experience with three cases of GVHD diagnosed over a period of 15 years in a total of 2,271 solid organ transplant recipients. CASE REPORTS: We describe three case reports: (1) a 3-week old neonate who developed GVHD 16 months after living-related liver transplant, (2) a 14-year old adolescent who developed GVHD 4 months following an unrelated cadaveric pancreas transplant and; (3) a 27-year old male who developed GVHD 18 days after simultaneous kidney-pancreas transplant from an unrelated donor. GVHD was confirmed through skin biopsies, engraftment profile from bone marrow biopsy and variable number tandem repeat analysis. Treatment strategies included use of corticosteroids and sirolimus monotherapy, corticosteroids and mesenchymal stromal cell therapy and reduction of immunosuppression. We observed that African-American race, sexual and HLA mismatching and cytomegalovirus infection may be high risk factors for development of GVHD following solid organ transplant. CONCLUSIONS: GVHD continues to be a rare but fatal complication following solid organ transplantation that demands a high index of clinical suspicion for diagnosis and management. Future approaches may focus on early recognition of risk factors and improving treatment protocols using a combination of mesenchymal stromal cell transplantation with pharmacotherapy.

Pretransplant transcriptome profiles identify among kidneys with delayed graft function those with poorer quality and outcome.

Robust biomarkers are needed to identify donor kidneys with poor quality associated with inferior early and longer-term outcome. The occurrence of delayed graft function (DGF) is most often used as a clinical outcome marker to capture poor kidney quality. Gene expression profiles of 92 preimplantation biopsies were evaluated in relation to DGF and estimated glomerular filtration rate (eGFR) to identify preoperative gene transcript changes associated with short-term function. Patients were stratified into those who required dialysis during the first week (DGF group) versus those without (noDGF group) and subclassified according to 1-month eGFR of >45 mL/min (eGFR(hi)) versus eGFR of ≤45 mL/min (eGFR(lo)). The groups and subgroups were compared in relation to clinical donor and recipient variables and transcriptome-associated biological pathways. A validation set was used to confirm target genes. Donor and recipient characteristics were similar between the DGF versus noDGF groups. A total of 206 probe sets were significant between groups (P < 0.01), but the gene functional analyses failed to identify any significantly affected pathways. However, the subclassification of the DGF and noDGF groups identified 283 probe sets to be significant among groups and associated with biological pathways. Kidneys that developed postoperative DGF and sustained an impaired 1-month function (DGF(lo) group) showed a transcriptome profile of significant immune activation already preimplant. In addition, these kidneys maintained a poorer transplant function throughout the first-year posttransplant. In conclusion, DGF is a poor marker for organ quality and transplant outcome. In contrast, preimplant gene expression profiles identify "poor quality" grafts and may eventually improve organ allocation.

En bloc kidney transplantation from pediatric donors: comparable outcomes with living donor kidney transplantation.

BACKGROUND: En bloc kidneys from pediatric donors have been considered suboptimal for transplantation to adult recipients and their outcomes have rarely been compared with living donor kidney transplantation (LDKT). Traditionally, there has been hesitancy in transplanting en bloc kidneys from donors weighing less than 10 kg due to high risk of technical complications. METHODS: Retrospective chart reviews were performed to compare outcomes after pediatric en bloc (n=20, mean donor weight 11.4 kg), standard criteria deceased (n=249), and living donor (n=215) kidney transplantation in adult recipients at our center. The outcomes after en bloc transplantation from young donors weighing less than or equal to 10 kg were compared with those from 11 to 15 kg donors. RESULTS: The 5-year graft survival after en bloc, standard deceased, and LDKT were 92%, 70%, and 88%, respectively (P=ns). There were no vascular complications, and urine leak was seen in 1 of 20 en bloc transplants. The 1-year serum creatinine of 1.1±0.2 mg/dL in recipients from less than or equal to 10 kg donors was comparable with 0.9±0.5 mg/dL in 11 to 15 kg group (P=ns). CONCLUSIONS: Excellent long-term outcome after pediatric en bloc kidney transplantation from donors weighing less than or equal to 15 kg are comparable with those after LDKT. By using meticulous surgical technique and judicious recipient selection criteria, technical graft losses can be minimized when using en bloc pediatric kidneys from donors weighing less than or equal to 10 kg. Use of pediatric en bloc kidneys should be encouraged continuously to address the problem of organ shortage.

High prevalence of vitamin D deficiency in African American kidney transplant recipients.

Kidney transplant patients are at high risk for developing Vitamin D(3) deficiency. The prevalence rates of 25(OH) Vitamin D(3) deficiency and its association with parathyroid hormone (PTH) levels in African American kidney transplant recipients have not been examined. We measured 25(OH) Vitamin D(3) and intact PTH concentrations in 38 African American transplant patients at our center in October 2006. We collected various laboratory data including serum creatinine, calcium, phosphate, alkaline phosphatase, and glomerular filtration rate. Vitamin D(3) deficiency was present in 57.8% of the patients and 94.7% had insufficiency. Ten of 22 (45%) patients with chronic kidney disease stage 3 had intact PTH more than or equal to 70 pg/mL. On multivariate analysis, 25(OH) Vitamin D(3) level was negatively correlated with intact PTH (P<0.01) and alkaline phosphatase level was positively associated with intact PTH levels (P<0.002). Vitamin D(3) deficiency and insufficiency is present in most of the African American kidney transplant patients.

Molecular pathways involved in loss of kidney graft function with tubular atrophy and interstitial fibrosis.

Loss of kidney graft function with tubular atrophy (TA) and interstitial fibrosis (IF) causes most kidney allograft losses. We aimed to identify the molecular pathways involved in IF/TA progression. Kidney biopsies from normal kidneys (n = 24), normal allografts (n = 6), and allografts with IF/TA (n = 17) were analyzed using high-density oligonucleotide microarray. Probe set level tests of hypotheses tests were conducted to identify genes with a significant trend in gene expression across the three groups using Jonckheere-Terpstra test for trend. Interaction networks and functional analysis were used. An unsupervised hierarchical clustering analysis showed that all the IF/TA samples were associated with high correlation. Gene ontology classified the differentially expressed genes as related to immune response, inflammation, and matrix deposition. Chemokines (CX), CX receptor (for example, CCL5 and CXCR4), interleukin, and interleukin receptor (for example, IL-8 and IL10RA) genes were overexpressed in IF/TA samples compared with normal allografts and normal kidneys. Genes involved in apoptosis (for example, CASP4 and CASP5) were importantly overexpressed in IF/TA. Genes related to angiogenesis (for example, ANGPTL3, ANGPT2, and VEGF) were downregulated in IF/TA. Genes related to matrix production-deposition were upregulated in IF/TA. A distinctive gene expression pattern was observed in IF/TA samples compared with normal allografts and normal kidneys. We were able to establish a trend in gene expression for genes involved in different pathways among the studied groups. The top-scored networks were related to immune response, inflammation, and cell-to-cell interaction, showing the importance of chronic inflammation in progressive graft deterioration.

Living kidney donors requiring transplantation: focus on African Americans.

Risks of kidney donation include a poorly characterized risk of late kidney failure. We hypothesized that African Americans (AA) kidney donors were at greater risk for kidney failure. The United Network for Organ Sharing/Organ Procurement Transplantation Network database was searched for patients who previously donated a kidney and were subsequently placed on the kidney transplant waiting list. We then compared the race of donors listed for kidney transplant to the race of all living donors during the same time period. Between 1993 and 2005, 8889 donors (14.3%) were AA and 42,419 (68.1%) were Caucasian. During this same time period, 102 previous kidney donors developed kidney failure and were listed for kidney transplantation. Although AAs comprised 14.3% of all living kidney donors, they constituted 44% of donors reaching the waiting list (P<0.001). These data provide indirect evidence that the risk of kidney failure may be exaggerated in AA donors.

Evaluation of gene panel mRNAs in urine samples of kidney transplant recipients as a non-invasive tool of graft function.

Non-invasive monitoring may be useful after kidney transplantation (KT), particularly for predicting acute rejection (AR). It is less clear whether chronic allograft nephropathy (CAN) is also associated with changes in urine cells. To identify non-invasive markers of allograft function in kidney transplant patients (KTP), mRNA levels of AGT, TGF-beta1, EGFR, IFN-gamma, TSP-1, and IL-10 in urine (Ur) samples were studied using QRT-PCR. Ninety-five KTP and 111 Ur samples were evaluated. Patients (Pts) were divided as, within six months (N = 31), and with more than six months post-KT (N = 64). KTP with more than six months post-KT were classified as KTP with stable kidney function (SKF) (N = 32), KTP with SKF (creatinine < 2 mg/dL) and proteinuria > 500 mg/24 h (N = 18), and KTP with biopsy proven CAN (N = 14). F-test was used to test for equality of variances between groups. IL-10 mRNA was decreased in Ur samples from KTP with less than six months post-KT (P = 0.005). For KTR groups with more than six months post-KT, AGT and EGFR mRNA were statistically different among KTP with SKF, KTP with SKF and proteinuria, and CAN Pts (P = 0.003, and P = 0.01), with KTP with SKF having higher mean expression. TSP-1 mRNA levels also were significantly different among these three groups (P = 0.04), with higher expression observed in CAN Pts. Using the random forest algorithm, AGT, EGFR, and TGF-beta1 were identified as predictors of CAN, SKF, SKF with proteinuria. A characteristic pattern of mRNA levels in the different KTP groups was observed indicating that the mRNA levels in Ur cells might reflect allograft function.