Chronic Allograft Damage Index Research Articles

A comparison between the superb microvascular imaging technique and conventional Doppler ultrasound in evaluating chronic allograft damage in renal transplant recipients

The present study comparatively evaluates the performance of conventional Doppler ultrasound and superb microvascular imaging (SMI) in delineating the cortical microvessels of the transplanted kidney and compares the chronic allograft damage index (CADI) based on the examination of biopsy specimens with Doppler ultrasound and SMI findings. Sixty-eight renal transplant recipients underwent kidney biopsy with the pre-diagnosis of rejection before undergoing renal Doppler ultrasound examination between January 2020 and October 2020. The distance between the kidney capsule and the vascular structure closest to the kidney capsule was measured at the level of the lower pole in the transplanted kidney using color Doppler ultrasound (CDUS), power Doppler ultrasound (PDUS), and the SMI technique. The kidney size, resistive index at the level of the arcuate artery in the lower pole of the kidney, and renal artery flow rates were also measured. The mean distance between the kidney capsule and the vessel was 2.44 ± 2.0 mm on CDUS, 1.34 ± 1.2 mm on PDUS, 0.99 ± 1.8 mm using the color SMI (cSMI) technique, and 0.86 ± 1.8 mm using the monochrome SMI (mSMI) technique. The study found that the SMI technique was superior to CDUS and PDUS in delineating the cortical microvasculature of the kidney. Both Doppler ultrasound examinations and the SMI technique proved effective in predicting the CADI (P = 0.006 for CDUS, P = 0.002 for PDUS, P = 0.018 for cSMI, and P = 0.027 for mSMI). Among conventional Doppler ultrasound examinations and the SMI technique, PDUS had the highest sensitivity, and cSMI had the highest specificity in differentiating high and low CADI values. Both the cSMI and mSMI techniques had similar sensitivity values, whereas only cSMI exhibited high specificity. CDUS had the lowest specificity value (P = 0.003 for CDUS, P = 0.002 for PDUS, P = 0.005 for cSMI, and P = 0.004 for mSMI). The present study is the first in the literature to demonstrate the utility of the distance between the kidney capsule and the vessels in predicting the CADI score and to compare the Doppler ultrasound examinations and SMI technique in doing so.

Evaluating the Link between BAFF System Gene Expression and Acute Rejection Development in Kidney Transplantation.

B-cell activating factor (BAFF) system signaling is critical for B-cell homeostasis, effector functions, and tolerance maintenance in transplants, but it has not been studied in kidney transplant recipients (KTRs). The aim was to analyze the changes in BAFF system expression in KTRs with/without acute rejection (AR/NAR). The BAFF system expression was analyzed by qPCR in 40 KTRs. A meta-analysis of BAFF system expression and histological renal damage was identified by the Chronic Allograft Damage Index (CADI) and performed from the GEO database. Proliferation-inducing ligand (APRIL) expression increased at three- and six-months post-KT (p = 0.014 and p < 0.001). B-cell maturation antigen (BCMA) expression increased at six-months post-KT (p = 0.038). BAFF expression remained stable in NAR-KTRs, but was increased in CADI concerning the No-CADI group at one year (p = 0.008). BCMA expression increased in the CADI group at one- (p = 0.001) and six-years post-KT (p = 0.024). At three months, the transmembrane activator and calcium modulator interactor (TACI) gene significantly elevated KTRs with DSAs (donor-specific antibody; p = 0.034). KTRs with DSAs significantly increase the B-cell activating factor receptor (R-BAFF; p = 0.021) and TACI (p = 0.018) between pre- and three-month post-KT. Changes in the expression of the BAFF system increase during post-KTR in the development of AR and chronic allograft damage, and could be an important pathological tool to detect and prevent kidney graft outcomes.

Improve in-depth immunological risk assessment to optimize genetic-compatibility and clinical outcomes in child and adolescent recipients of parental donor kidney transplants: protocol for the INCEPTION study

BackgroundParental donor kidney transplantation is the most common treatment option for children and adolescents with kidney failure. Emerging data from observational studies have reported improved short- and medium-term allograft outcomes in recipients of paternal compared to maternal donors. The INCEPTION study aims to identify potential differences in immunological compatibility between maternal and paternal donor kidneys and ascertain how this affects kidney allograft outcomes in children and adolescents with kidney failure.MethodsThis longitudinal observational study will recruit kidney transplant recipients aged ≤18 years who have received a parental donor kidney transplant across 4 countries (Australia, New Zealand, United Kingdom and the Netherlands) between 1990 and 2020. High resolution human leukocyte antigen (HLA) typing of both recipients and corresponding parental donors will be undertaken, to provide an in-depth assessment of immunological compatibility. The primary outcome is a composite of de novo donor-specific anti-HLA antibody (DSA), biopsy-proven acute rejection or allograft loss up to 60-months post-transplantation. Secondary outcomes are de novo DSA, biopsy-proven acute rejection, acute or chronic antibody mediated rejection or Chronic Allograft Damage Index (CADI) score of > 1 on allograft biopsy post-transplant, allograft function, proteinuria and allograft loss. Using principal component analysis and Cox proportional hazards regression modelling, we will determine the associations between defined sets of immunological and clinical parameters that may identify risk stratification for the primary and secondary outcome measures among young people accepting a parental donor kidney for transplantation. This study design will allow us to specifically investigate the relative importance of accepting a maternal compared to paternal donor, for families deciding on the best option for donation.DiscussionThe INCEPTION study findings will explore potentially differential immunological risks of maternal and paternal donor kidneys for transplantation among children and adolescents. Our study will provide the evidence base underpinning the selection of parental donor in order to achieve the best projected long-term kidney transplant and overall health outcomes for children and adolescents, a recognized vulnerable population.Trial registrationThe INCEPTION study has been registered with the Australian New Zealand Clinical Trials Registry, with the trial registration number of ACTRN12620000911998 (14th September 2020).

Response to treatment in kidney transplant recipients with acute antibody-mediated rejection: A follow-up biopsy study .

The aim of this study is to evaluate the efficacy of a treatment protocol for the management of acute antibody-mediated rejection (AAMR) and mixed-type rejection (MTR), both histopathologically and clinically. Of the 362 cases undergoing kidney transplantation from January 2010 to January 2018, patients with AAMR or MTR in the first 3 months after transplantation were included. All patients had follow-up biopsy (Bx) after treatment. 33 (9.1%) patients had diagnosis of AMR. Mean follow-up was 35 ± 20 months. 28.5% of patients had poor clinical progression at the last follow-up. Of the 25 patients with functional grafts, the mean serum creatinine was 1.6 ± 0.6 mg/dL for live and 2.1 ± 1.0 mg/dL for deceased transplant recipients. In diagnostic biopsies, there were 61% MTR. In follow-up Bx, after treatment, both C4d positivity and the severity of rejection had decreased while the mean chronic allograft damage index (CADI) score and transplant glomerulopathy showed an increase. With effective antibody mediated rejection (AMR) therapy, renal function parameters were significantly improved. Histologically, improvement in tubulointerstitial inflammation may be responsible for this process. However, progressive chronic changes, particularly in the glomeruli, are noteworthy.

Use of intravoxel incoherent motion imaging to monitor a rat kidney chronic allograft damage model

BackgroundChronic allograft damage (CAD) is the leading cause of long-term graft dysfunction. A noninvasive method that can diagnose CAD early and monitor its development is needed.MethodsKidneys from Fisher rats were transplanted into Lewis rats to establish a CAD model (n = 20). The control group underwent syngeneic kidney transplantation (n = 20). The serum creatinine of the rats was monitored. At 4, 12, and 20 weeks after modeling, a magnetic resonance imaging (MRI) examination was performed. The apparent diffusion coefficient (ADC), pseudo diffusion coefficient (D*), true diffusion coefficient (D) and perfusion fraction (f) of the two groups were analyzed. Chronic allograft damage index (CADI) scoring was used to evaluate the transplanted kidney specimens. Immunohistochemistry was used to detect the expression of fibrosis markers in the transplanted kidney tissues and to analyze their correlations with all MRI parameters.ResultsThe transplanted kidneys in the experimental group developed CAD changes before the appearance of elevated creatinine. The MRI parameters in the experimental group [ADC (1.460 ± 0.109 VS 2.095 ± 0.319, P < 0.001), D (1.435 ± 0.102 VS 1.969 ± 0.305, P < 0.001), and f (26.532 ± 2.136 VS 32.255 ± 4.013, P < 0.001)] decreased, and D* (20.950 ± 2.273 VS 21.415 ± 1.598, P = 0.131) was not significantly different from those in the control group. ADC, D and f were negatively correlated with the CADI and the α-SMA and vimentin expression levels.ConclusionIntravoxel incoherent motion (IVIM) imaging could detect CAD earlier than creatinine and reflect the degree of fibrosis in grafts quantitatively.

SDF‑1/CXCR4 induces epithelial‑mesenchymal transition through activation of the Wnt/β‑catenin signaling pathway in rat chronic allograft nephropathy.

Epithelial-mesenchymal transition (EMT) has been demonstrated to serve a crucial role in the progression of interstitial fibrosis, which is one of the principal pathological features of chronic allograft nephropathy (CAN). However, to the best of our knowledge, the mechanisms of EMT in CAN have not been investigated. In the present study, the effect of stromal cell-derived factor 1 (SDF-1) and the Wnt signaling pathway on the progression of EMT following kidney transplantation was investigated. The CAN model was established using Fisher 344 and Lewis rats, treated with low-dose cyclosporine with or without AMD3100. CAN was confirmed by the pathological alterations and chronic allograft damage index scoring, and EMT was confirmed by western blotting and reverse transcription-quantitative polymerase chain reaction. In the AMD3100 group, there were lower expression levels of α-SMA and higher expression levels of E-cadherin, which indicated that CAN and EMT were ameliorated by AMD3100. The kidney tissue was analyzed using an mRNA + long noncoding (lnc)RNA microarray. A total of 506 mRNAs and 404 lncRNAs were demonstrated to be significantly differentially expressed between the two groups, which revealed the involvement of SDF-1/CXC chemokine receptor 4 (CXCR4) and the Wnt pathway. SDF-1 was demonstrated to induce EMT in vitro through the upregulation of α-SMA, downregulation of E-cadherin and the wound healing assay, and in the rat renal tubular epithelial cells via the nuclear accumulation of β-catenin, which were all inhibited by either AMD3100 or DKK-1. CXXC finger protein 5 (CXXC5), a negative regulator of the Wnt pathway, was downregulated following treatment with SDF-1, which was inhibited by AMD3100 but not by DKK-1. Thus, CXXC5 may be a regulator downstream of SDF-1/CXCR4 in EMT. In conclusion, SDF-1/CXCR4 induces EMT of renal tubular epithelial cells with the involvement of the Wnt pathway, which may be a novel mechanism and therapeutic target in kidney allograft fibrosis of rats.

The value of diffusion tensor imaging in early diagnosis of chronic allograft nephropathy and monitoring graft fibrosis in rats

Objective To estimate the value of diffusion tensor imaging (DTI) in early diagnosis of chronic allograft nephropathy (CAN) and monitoring of graft fibrosis in rat models. Methods Thirty CAN rat models were established as experimental group by transplanting Fisher donor kidneys into Lewis recipients. Thirty Lewis rats that received Lewis kidneys served as control group. Serum creatinine (SCr) was monitored regularly every two weeks from 14 days after transplantation. Eight rats were randomly selected by random number table method and underwent DTI examination at 4, 12, 20 weeks after modeling. DTI scans were performed on the renal cortex and medulla to measure apparent diffusion coefficient (ADC) and fractional anisotropy (FA). From the remaining 22 rats in each group, 6 rats were randomly selected and underwent pathological analysis at 4, 12, 20 weeks after modeling. Histological changes in the kidney were evaluated by chronic allograft damage index (CADI) scores. The expression of alpha-smooth muscle actin (α-SMA) and Vimentin were quantitatively measured. The differences in creatinine, DTI parameters, CADI score, α-SMA, Vimentin expression level were analyzed by two independent samples t test in two groups, the differences among CADI score, α-SMA, Vimentin expression level of the experimental group were compared using ANOVA. The correlations among DTI parameters and CADI score, α-SMA and Vimentin expression level were analyzed using Pearson analysis. Results The creatinine in the experimental group increased continuously, and the creatinine in the control group showed no significant increase. The difference in creatinine between the two groups was statistically significant from 8th week after operation (P<0.01). There was no obvious difference in the size and signal intensity of transplanted kidneys in control group at different time points. Compared with the control group, the graft kidney in the experimental group at the 4 weeks demonstrated increased signal intensity with mild increased volume of kidney, and the boundaries between cortex and medulla were not clear. The cortex and medulla showed gradually increased signal intensity, heterogeneous signal distribution and marginal haziness over time. The ADC and FA value of renal cortex and medulla in experimental group were significantly lower than those in control group at 4, 12, 20 weeks (P<0.05). The ADC and FA values of the cortex and medulla gradually decreased in the experimental group over time, while the values of the parameters in the control group did not show a significant decrease. The ADC and FA values of the cortex and medulla were negatively correlated with the scores of CADI, and the expression level of α-SMA, Vimentin in the experimental group(r=-0.50 to-0.85, P<0.01). Conclusion DTI can be an effective technique for early diagnosis of CAN and monitoring of graft fibrosis process. Key words: Kidney transplantation; Chronic allograft nephropathy; Diffusion tensor imaging; Comparative study

Biopsy transcriptome expression profiling to identify kidney transplants at risk of chronic injury: a multicentre, prospective study

Chronic injury in kidney transplants remains a major cause of allograft loss. The aim of this study was to identify a gene set capable of predicting renal allografts at risk of progressive injury due to fibrosis. This Genomics of Chronic Allograft Rejection (GoCAR) study is a prospective, multicentre study. We prospectively collected biopsies from renal allograft recipients (n=204) with stable renal function 3 months after transplantation. We used microarray analysis to investigate gene expression in 159 of these tissue samples. We aimed to identify genes that correlated with the Chronic Allograft Damage Index (CADI) score at 12 months, but not fibrosis at the time of the biopsy. We applied a penalised regression model in combination with permutation-based approach to derive an optimal gene set to predict allograft fibrosis. The GoCAR study is registered with ClinicalTrials.gov, number NCT00611702. We identified a set of 13 genes that was independently predictive for the development of fibrosis at 1 year (ie, CADI-12 ≥2). The gene set had high predictive capacity (area under the curve [AUC] 0·967), which was superior to that of baseline clinical variables (AUC 0·706) and clinical and pathological variables (AUC 0·806). Furthermore routine pathological variables were unable to identify which histologically normal allografts would progress to fibrosis (AUC 0·754), whereas the predictive gene set accurately discriminated between transplants at high and low risk of progression (AUC 0·916). The 13 genes also accurately predicted early allograft loss (AUC 0·842 at 2 years and 0·844 at 3 years). We validated the predictive value of this gene set in an independent cohort from the GoCAR study (n=45, AUC 0·866) and two independent, publically available expression datasets (n=282, AUC 0·831 and n=24, AUC 0·972). Our results suggest that this set of 13 genes could be used to identify kidney transplant recipients at risk of allograft loss before the development of irreversible damage, thus allowing therapy to be modified to prevent progression to fibrosis. National Institutes of Health.

Use of Contrast-Enhanced Ultrasonography to Evaluate Chronic Allograft Nephropathy in Rats and Correlations between Time-Intensity Curve Parameters and Allograft Fibrosis

This study quantitatively analyzed changes in the hemodynamic characteristics of renal allografts at different stages in a rat chronic allograft nephropathy (CAN) model as well as the relationship between hemodynamic parameters and renal allograft fibrosis using contrast-enhanced ultrasonography (CEUS). The experimental group used a CAN rat model (n = 30), and the control group used an orthotopic syngeneic renal transplant model (n = 30). After surgery, creatinine clearance rates were regularly monitored every 2 wk. The checking times were set at 4, 12 and 24 wk after surgery, which represent early, middle and late stage of CAN, respectively. At different stages of CAN, eight rats from each group were randomly selected for CEUS examination. Time-intensity curve (TIC) parameters, including rise time, peak intensity, mean transit time, area under the curve, wash-in slope, time-to-peak and α-smooth muscle actin (α-SMA) expression; Vimentin expression; and chronic allograft damage index scores were evaluated by linear correlation analysis. Before the creatinine clearance rate showed significant abnormalities, the renal allografts in the experimental group had already presented pathologic changes associated with CAN. In the early stage after surgery, compared to the TIC curve of the control group, the experimental group showed increased rise time, mean transit time, area under the curve and time-to-peak, and decreased wash-in slope (p < 0.05). Chronic allograft damage index scores and the expression levels of α-SMA and Vimentin proteins in renal allografts were correlated with TIC parameters (p < 0.05). Compared to creatinine clearance rate, CEUS can detect CAN at earlier stages. The correlations between TIC-related parameters and the expression levels of α-SMA and Vimentin in renal allografts indicate that CEUS is a feasible way to assess the degree of renal allograft fibrosis quantitatively.

CXC Chemokine Receptor 4 (CXCR4) Antagonist, a Novel Pathway to Prevent Chronic Allograft Nephropathy.

BACKGROUND Chronic allograft nephropathy (CAN) remains a major problem for long-term graft survival and different pathways participate in its development. CXC chemokine receptor 4 (CXCR4) is significantly upregulated following renal injury and fibrotic response. We investigated the effect of AMD3100, a CXCR4 antagonist, on the development of CAN in rat models. MATERIAL AND METHODS CAN rat models (n=20) were established using male Fisher 344 to Lewis rats. Rats in the experimental group (n=10) were treated with AMD3100 (1 mg/kg/day subcutaneously, 0-12 weeks), rats in the control group (n=10) were treated with saline. The serum creatinine levels were monitored every week. Kidney grafts were harvested 12 weeks after modeling for histological analysis. We used chronic allograft damage index (CADI) scores to evaluate each group. Q-PCR and Western blotting were used to measure CXCR4, TGF-β1/Smad3 signaling pathway and α-smooth muscle actin (α-SMA) expression in renal allograft tissue. RESULTS CXCR4 expression was increased significantly in the control group which developed intense chronic changes after 12 weeks. Histological changes of CAN in the experimental group were ameliorated by AMD3100 which also had better graft function compare to the control group. AMD3100 significantly blunted the increase in the mRNA expression level of CXCR4, TGF-β1/Smad3, and α-SMA. A significant reduction in TGF-β1 and α-SMA protein content was observed only in the experimental group as shown in a representative Western blot. CONCLUSIONS Based on these findings, CXCR4 expression may mediate in part the development of CAN. AMD3100 may ameliorate histological changes of CAN and maintain better allograft function. It blunts downstream effects of TGF-β1 signaling and fibroblast activation. Therefore, antagonism of CXCR4 may provide a novel way to prevent the development of CAN.

Identification of a Molecular Signature to Predict the Progression of Kidney Fibrosis Post Transplantation.

Chronic injury in kidney transplants remains a major cause of graft loss. The aim of the study was to identify a predictive gene set capable of classifying renal grafts at risk for progressive injury due to fibrosis. The Genomics of Chronic Allograft Rejection (GoCAR) study is a prospective, multicenter study. Biopsies obtained prospectively from renal allograft recipients (n=159) with stable renal function 3 months after transplantation were analyzed for gene expression by microarray. Genes correlating with 12-month Chronic Allograft Damage Index (CADI) but not 3 month CADI were identified, and analysis performed on 101 recipients with 12-month CADI to determine the predictive capacity of this gene set relative to current clinical and histopathology parameters. We identified a 13 gene set that was independently predictive for the development of chronic allograft damage at 1 year. The high predictive capacity of the gene set (0.947) was superior to clinical indicators (AUC 0.73). While histological parameters failed to discriminate between grafts in which the CADI progressed from non-progressors, the predictive gene set accurately differentiated between these biopsies (AUC=0.987). Testing on an independent cohort within GoCAR (n=45) by qPCR and three independent publically available microarray expression gene sets validated our gene sets ability to predict renal allograft injury. A gene set obtained at 3 months from stably functioning renal allografts correlated with the progression of established markers for chronic allograft damage at 12 months and proved superior to clinico-pathological variables currently used in clinical practice to in identifying renal transplant recipients at risk of graft loss.

Proteomic Analysis Identified Urine Proteins Predictive of Chronic Allograft Injury.

Aim: To correlate early urine protein biomarkers with long term kidney transplant histology and function; to assess biomarker potential to predict subsequent allograft dysfunction and chronic interstitial fibrosis. Method: Patient cohort was selected from a single center within the GoCAR study who had urine samples at 3 and 12 months and protocol biopsies at 0, 3, and 12 months post transplant. Patients were grouped by chronic damage scores using Banff and Chronic Allograft Damage Index (CADI) from 12 month biopsies or change in estimated glomerular filtration rate (eGFR). Urine proteins at 3 and 12 months associated with chronic damage at 12 months were identified by two-dimensional differential in gel electrophoresis (2D-DIGE) and tandem mass spectrometry. Differential protein abundance was calculated using DeCyder software and further interrogated using the STRING network program. Results: Delayed graft function occurred in 25% and biopsy proven acute rejection in 17% of patients. Acute and chronic damage scores were low at 3 months. Proteinuria or eGFR were not significantly different between chronic damage analysis groups. From the 3 month urine, 9 proteins including kininogen, MASP2 and cystatin M correlated to fibrosis at 12 months (5 with Banff, 4 with CADI) and 2 proteins correlated with change in eGFR. The top KEGG pathway in the STRING network were coagulation and complement cascades. Follow up 12 month urine analysis based on the same chronic damage groups revealed 11 proteins, 4 identified in the previous 3 month analysis and 7 new proteins, including CD14 and β2 microglobulin. The top KEGG pathway at 12 months was antigen processing and presentation. Conclusion: Using traditional proteomic techniques, we have identified potential non-invasive biomarkers that are predictive of chronic allograft damage. The dominant urine proteome alters between 3 and 12 months expressing a different panel of proteins. While early urine protein signatures predict subsequent damage, validation in larger and more diverse cohorts is required.

TGF-β1 Expression in Kidney Allograft Protocol Biopsies during Cyclosporine: a Therapy

TGF-β1 expression has been described to increase along with time from transplantation and has also been linked to allograft dysfunction and toxic effects of cyclosporine. Our aim was to correlate intragraft TGF-β1 expression with cyclosporine exposure after kidney transplantation. Altogether 53 kidney allograft protocol biopsies from 42 patients on a low-dose cyclosporine-based regimen obtained at 3, 6, and 12 months were classified according to Banff and the chronic allograft damage index (CADI). TGF-β1 expression in tubules, glomeruli, vessels, and inflammatory cells was semi-quantitatively scored and correlated with cyclosporine concentrations (C0 and C2), CADI, and graft function. TGF-β1 expression was mildly increased along time from transplantation, but the results were not statistically significant. TGF-β1 expression was neither related to CADI nor to the use of ACE inhibitors/ARB. TGF-β1 expression in the kidney was not correlated with C0 or C2 levels or kidney graft function during follow-up. In protocol biopsies from patients on low-dose cyclosporine regimen, expression of TGB-β1 was not significantly increased along time since transplantation, and did not correlate with cyclosporine exposure. Our findings suggest that the toxic effects of low-dose cyclosporine on TGF-β expression may be milder than previously thought.

Sirolimus inhibits lymphangiogenesis in rat renal allografts, a novel mechanism to prevent chronic kidney allograft injury

Lymphangiogenesis occurs in renal allografts and it may be involved in the maintenance of the alloreactive immune response and thus participate in the development of chronic kidney allograft injury. Sirolimus (SRL) has been shown to inhibit lymphangiogenesis. The aim of this study was to describe lymphangiogenesis and its regulation during the development of chronic kidney allograft injury and to investigate the effect of SRL on allograft lymphangiogenesis and chronic kidney allograft injury. A rat renal transplantation model was used. Allografts treated with cyclosporine A or with SRL were analyzed in various time points. Syngenic transplantations were used as controls. Kidney function was followed with serum creatinine. Histology was analyzed by Chronic Allograft Damage Index (CADI). Immunohistochemistry was used to detect lymphatic vessels, VEGF-C and VEGFR-3. In cyclosporine-treated allografts VEGF-C/VEGFR-3 pathway was strongly upregulated leading to extensive lymphangiogenesis 60days after transplantation. Lymphangiogenesis correlated positively with the CADI score. Sirolimus efficiently inhibited lymphangiogenesis, improved graft function and attenuated the development of chronic kidney allograft injury when compared with cyclosporine. In conclusion, lymphangiogenesis is associated with chronic kidney allograft injury and SRL is a potent inhibitor of lymphangiogenesis in renal allografts. Inhibition of lymphatic proliferation could mediate the nephroprotective properties of SRL.

Stanniocalcin Supports the Functional Adaptation of Adult-Sized Kidneys Transplanted Into the Pediatric Recipients

The functional adaptation of adult-sized kidney (ASK) grafts to the recipient's size is not completely reversible and is associated with irreversible histologic damage in the smallest recipients. The aim of the study was to unveil the molecular mechanisms underlying the functional adaptation of ASK transplants to small pediatric recipients. Because physiologic and functional adaption of ASK in infants is seen maximally at 3 months after transplantation, we selected 21 pediatric recipients of an ASK with protocol biopsies at engraftment and 3 and 6 months, without delayed graft function or interval rejection, and we conducted whole-genome expression profiles of the renal allograft biopsies at 3 months and correlated results with subsequent absolute glomerular filtration rate (aGFR). Seven hundred twenty-four unique genes correlated significantly with aGFR (q value <5%). Canonical pathway analysis identified overrepresentation of relevant pathways involved in regulation of tubular salt reabsorption and enzymatic pathways for organ development and hypertrophy. The single gene that correlated best with aGFR was stanniocalcin 1 (STC1). STC1 expression also correlated with the recipient's size at the time of transplantation and the chronic allograft damage index at 6 months. Functional adaptation of adult-sized grafts to the pediatric recipient is associated with molecular adaptation for normal-volume homeostasis of the recipient. Our finding also suggests that stanniocalcin (STC1) plays an important role on functional adaption in pediatric kidney transplantation.

Chronic Kidney Disease After Nonrenal Solid Organ Transplantation

It is proposed that chronic calcineurin inhibitor (CNI) nephrotoxicity has a central role in chronic kidney disease after nonrenal solid organ transplantation (NRSOT), although there are little data on renal histology in this setting. The aim of this study was to assess the histological features and renal outcomes of a cohort of patients with chronic kidney disease after NRSOT. Renal biopsies of 62 NRSOT recipients were evaluated for histological diagnoses. Biopsies were graded for chronic allograft damage index parameters and for arteriolar hyalinosis. The sum of all chronic allograft damage index parameters and arteriolar hyalinosis scores was called chronic damage index. The biopsies were performed at a median of 4 (range: 0.3-15.9) years after NRSOT and at serum creatinine of 318±17.7 μmol/L (mean±standard deviation). Twenty-two (35.5%) biopsies showed predominant features of chronic CNI nephrotoxicity, 27 (43.5%) predominant features of hypertensive nephropathy, and 12 (19.3%) an alternative primary renal pathology. Twenty-four (38.7%) patients had progression to end-stage renal disease, at a median of 1.5 (0-10.1) years after biopsy and 6.9 (0.3-19.2) years after NRSOT. The risk of renal progression was associated with in situ damage measured by chronic damage index. Although CNI nephrotoxicity is an important cause of renal failure after NRSOT, many patients do not have overt histological evidence of CNI toxicity. Quantitative parameters of chronic damage can stratify renal prognosis.

Effect of steroid-free low concentration calcineurin inhibitor maintenance immunosuppression regimen on renal allograft histopathology and function

The most common cause of late kidney transplant failure is insidiously progressive renal dysfunction associated with organ scarring and fibrosis. Advanced donor age, delayed graft function, calcineurin toxicity and repeated acute rejection episodes are risk factors for this pathophysiology. We employed 3, 12 and 24 months surveillance renal biopsies, scored using the Chronic Allograft Damage Index (CADI), with periodic estimates of glomerular filtration rate (eGFR) to assess the effect of a steroid-free maintenance immunosuppression regimen on allograft histology and function. Ninety-one patients were induced with Alemtuzumab and then treated with mycophenolate sodium and low trough concentrations of tacrolimus. Fifty-six of 91 patients followed for 24 months showed no clinical rejection and in 16 more only minimal histological or borderline changes as defined by Banff criteria were observed. Histologically acute rejection was observed in 14 patients including two detected on surveillance biopsy. Five patients refused biopsies but showed stable eGFR for 24 months. Graft histopathology in the group with no rejection did not worsen. In contrast, nearly half the patients with acute rejection showed progression of CADI scores and a total of four grafts were lost over the 2 years. The 16 patients with borderline rejection changes exhibited stable glomerular filtration rate throughout, but 12.5% showed progression of CADI scores in the 12- to 24-month period. Following Alemtuzumab induction and in conjunction with low-dose tacrolimus and mycophenolate, continuous steroid therapy was not required to prevent progressive injury or preservation of graft function in patients without biopsy-proven acute rejection. Scored surveillance renal biopsies provide a useful tool to monitor transplanted kidneys.

Conversion to Low-Dose Tacrolimus or Rapamycin 3 Months After Kidney Transplantation: A Prospective, Protocol Biopsy-Guided Study

Long-term survival of kidney allografts is primarily limited by a progressive decline in function characterized by the presence of interstitial fibrosis (IF) and tubular atrophy (TA) on biopsy. Since chronic calcineurin-inhibitor (CNI) drug toxicity has been implicated as a significant cause of IF/TA, a major effort in transplantation has been to decrease or eliminate CNI therapy. We now report the clinical and histological consequences of converting renal transplant recipients at 3 months to either very low levels of tacrolimus (TAC; 4–6 ng/mL) or sirolimus (SRL; 6–10 ng/mL) therapy. Fifty-eight enrollees in this prospective randomized trial received low-dose (2.9 ± 0.6 mg/kg) rabbit antithymocyte globulin induction followed by standard doses of TAC (10–15 ng/mL), mycophenolic acid, and low-dose steroids for 3 months. Protocol biopsies were performed at implantation and 3 and 12 months. Six patients had evidence of either borderline changes ( n = 5) or grade 1A rejection ( n = 1) on the 3-month protocol biopsy and were not randomized. Only one patient had clinically evident rejection that occurred after randomization to SRL. One patient in each group had borderline changes at 12 months. Renal function (estimated glomerular filtration rate) was equivalent in both groups at 12 months (TAC 74 ± 15 vs SRL 66 ± 18 mL/min, P = .22). Chronic allograft damage index scores at 1 year were similar in both groups (TAC 2.8 ± 2.4 vs SRL 2.0 ± 2.7, P = .71). The percentage of patients with IF/TA scores greater than 2 at 1 year was low in both groups (TAC 12% vs SRL 9%, P = .78). Therefore, in a low-risk population defined as having a normal 3-month protocol biopsy, TAC levels can be successfully decreased to very low concentrations. One-year graft function and histology were equally well maintained with either low-dose TAC or SRL immunosuppression.

Donor risk score and baseline biopsy CADI value predict kidney graft outcome

Different donor parameters and baseline biopsy have been used to assess the quality of donor organs. There is, however, no consensus which risk factors and chronic changes in the donor kidney can be accepted for transplantation. The study included 481 deceased organ donors and their 829 kidney recipients transplanted during 1995-2005. The biopsies were re-evaluated according to the Banff 97 classification. The prognostic significance of donor risk factors and Chronic Allograft Damage Index (CADI) was analyzed. We propose a new donor risk score, calculated as the count of positive risk factors from a defined set of factors in the medical history of the donor. This donor risk score predicts histological quality of the kidney, graft function, and survival. Transplantations from donors with donor risk score >4 had significantly decreased graft survival compared to those with donor risk scores 0-4; the five-yr death-censored graft survivals were 83% vs. 93%, respectively. High donor CADI score (>3) was associated with worse graft function and survival. Three-yr glomerular filtration rate declined from 82 to 49 mL/min with donor CADI increase from 0 to ≥4. Our results show that high donor risk score and CADI value reflect low functional reserve and risk for poor graft outcome.

Integrative Analysis of -Omics Data and Histologic Scoring in Renal Disease and Transplantation: Renal Histogenomics

The histologic scoring of renal biopsies is still the gold standard for renal disease classification. The Banff classification scheme and the chronic allograft damage index are histopathologic scoring schemes widely used in renal transplantation. The determination of genome-wide gene expression profiles in human renal biopsies has the potential to serve as independent validation data sets and also provide a more precise evaluation of the functional status behind the visible morphologic alterations. It is expected that results from high-throughput-omics experiments will lead to improved classification schemes in the near future as also discussed at recent Banff meetings. In this review we give an overview on-omics studies, focusing on the association of molecular changes on the transcript as well as on the protein level and morphologic scoring schemes in renal disease and transplantation.