Chronic Allograft Damage Index Score 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.

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

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.

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.

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.

Association of immune cell function assay with protocol biopsy findings and viral infections in well matched kidney transplant recipients

Cylex Immune Cell Function Assay (ICFA) is in clinical use, but little is known about its association with screening of viral infections or findings in protocol biopsies. We analyzed ICFA in our well-matched kidney transplant population. Helsinki University Hospital patients who received a kidney transplant after July 2007 were analyzed. Patients with at least 6 months follow-up and ICFA measured together with the screening for cytomegalovirus (CMV), or polyomaviruses from urine or plasma, or patients with a protocol biopsy at 6 or 12 months taken at the time of the ICFA were included (n = 27). Immunosuppression was usually implemented with mycophenolate mofetil (MMF), steroids and cyclosporine A (CyA). Biopsies were analyzed with chronic allograft damage index (CADI). Mean immune response in 61 samples was 368 +/- 179 ATP ng/ml. Immune response was lower during BK virus (BKV) or CMV viremia compared to no viremia (p = 0.009 and p = 0.017), and no viremia was seen if immune response was > 380. BK or JC viruria was not associated with low immune response. Immune responses did not differ between patients with high or low CADI scores or between patients with immune activation or no immune activation in biopsies. Immune response in our population was higher than previously reported without increased risk of rejections. ICFA correlated with viremia but not with findings in protocol biopsies. The optimal immune response in our population needs further studies.

Assessment of Chronic Renal Allograft Nephropathy Using Contrast-Enhanced MRI: A Pilot Study

Renal allograft function monitoring has traditionally relied on functional markers such as creatinine level. Such markers are insensitive, and invasive ultrasound-guided protocol biopsies are used for allograft evaluation. This pilot study evaluates the association between renal perfusion measured noninvasively with contrast-enhanced MRI and the histologic severity of chronic allograft nephropathy. Chronic allograft nephropathy severity was estimated from protocol biopsy specimens using the chronic allograft damage index. We prospectively selected four patients considered to have severe chronic allograft nephropathy (chronic allograft damage index score > 4) and six patients considered to have stable allograft function (chronic allograft damage index score <or= 4). Renal perfusion (milliliters per minute per gram) was estimated during passage of a gadopentetate dimeglumine bolus using an up-slope method relating the delivery of gadopentetate dimeglumine to tissue from the supplying artery. Two levels of the transplant kidney were evaluated. The association between average MRI renal perfusion of both slices and chronic allograft damage index score was studied using multiple linear regression. We observed a statistically significant association between chronic allograft damage index score and MRI perfusion. MRI perfusion was significantly lower in the four patients with a chronic allograft damage index score of > 4 than in the other patients (1.94 vs 2.43 mL/min/g, respectively; p = 0.03). The effect size for this difference was large (d = 1.7). The R(2) for the linear regression model was 0.53. We observed an association between contrast-enhanced MRI renal perfusion and chronic allograft nephropathy severity. Further studies are needed to confirm this preliminary finding and to evaluate the role of contrast-enhanced MRI renal perfusion as a screening test for allograft dysfunction and potential utility in patient management.

Impact of glucose metabolism abnormalities on histopathological changes in kidney transplant protocol biopsies

The impact of post-transplant diabetes (PTDM) on kidney transplant histopathology has been poorly described. We examined the association of glucose metabolism abnormalities on the progression of histopathological changes in serial protocol biopsies. Helsinki University Hospital kidney transplant recipients during 2004-2006 were followed up. Patients with pre-existing diabetes or 2-h oral glucose tolerance test (OGTT) performed at 3 months, and protocol biopsies taken at 0 and 12 months were analyzed (n = 76). Diabetes was defined according to WHO/ADA. Histology was analyzed with chronic allograft damage index (CADI). Altogether 32 patients had pre-existing diabetes. In OGTT at 3 months, four showed PTDM, eight impaired glucose tolerance (IGT), two impaired fasting glucose, and 30 normal glucose tolerance. Patients with impaired glucose metabolism were older (P = 0.005), received grafts from older donors (P = 0.04), and had reduced renal function at 12 months (P = 0.003). In patients with IGT or PTDM, 2-h postload glucose values in OGTT correlated with CADI at 12 months (R = 0.84, P = 0.001) and with the change in CADI score between 0 and 12 months (R = 0.67, P = 0.025). Graft survival was reduced in patients with pre-existing diabetes (P = 0.01). Glucose abnormalities were associated with the progression of histopathological changes, especially in patients with already compromised kidneys, supporting the harmful role of PTDM to the kidney allograft.

Prediction of chronic allograft damage index of renal allografts using serum level of plasminogen activator inhibitor‐1

Plasminogen activator inhibitor-1 (PAI-1) plays an important role in renal fibrosis. We conducted this study to examine whether serum PAI-1 has a role in predicting chronic allograft nephropathy (CAN). Fifty kidney transplant recipients receiving graft biopsies were enrolled. The pathologic diagnoses were acute tubular necrosis (ATN; n = 12), borderline rejection (BR; n = 7), acute rejection (ACR; n = 12), CAN (n = 11), polyomavirus nephropathy (PVN; n = 3) and others (n = 5; glomerulopathy, n = 4; calcineurin inhibitor nephropathy, n = 1). The serum level of PAI-1 and chronic allograft damage index (CADI) score of each patient were determined. The CADI score of all patients was 4 (0-10) (median and range) and in each group was ATN 0.5 (0-4), BR 2.0 (1-4), ACR 4.0 (2-8), CAN 5.0 (4-10), PVN 7 (4-8) and others 2 (0-8). The serum PAI-1 level of each group was ATN 9.38 (2.35-14.52) ng/mL, BR 10.09 (0.61-18.06) ng/mL, ACR 11.08 (2.32-20.68) ng/mL, CAN 14.51 (3.66-21.12), PVN 14.79 (13.94-21.94) and others 16.35 (4.05-21.01) ng/mL. CADI score is associated with serum PAI-1 activity (r = 0.405, p = 0.003) and is inversely associated with serum creatinine (r = -0.348, p = 0.011), but not with estimated glomerular filtration rate (p = 0.124). Serum PAI-1 level has the potential to be a marker to predict CADI score, the quantitative score of CAN.

Histogenomics: Association of Gene Expression Patterns With Histological Parameters in Kidney Biopsies

Several studies investigated the association of histologic scores of donor kidney biopsies obtained before engraftment with posttransplant outcomes. Discrimination and goodness of fit of these scores, however, is low. Thus, we sought to identify and elucidate the performance of molecular rather than histologic markers for this purpose using whole genome gene expression microarray experiments. We identified 80 unique differentially regulated genes in 82 samples, showing no histologic damage versus those with histologic damage, based on the Chronic Allograft Damage Index (CADI) and acute tubular injury. Main biological categories enriched with up-regulated genes in damaged tissue were "immunity and defense," "cell communication," or "apoptosis." Interestingly, genes involved in cell structure, cell adhesion, and protein trafficking were specific for tubular atrophy. Histology (CADI score) explained only 14% of the variability of 1 year creatinine (adjusted R2 for panel-reactive antibodies, biopsy confirmed acute rejection, and sum of human leukocyte antigen mismatches) whereas a combination of three biomarkers without clinical covariables explained 28%. The three molecular markers are the NLR family, pyrin domain containing 2 (NLRP2), immunoglobulin J polypeptide, and the regulator of G-protein signaling 5. In summary, we identified biomarkers in transplant kidney biopsies, which are predictive for medium-term allograft function.

The utility of 6-month protocol renal biopsy under modern immunosuppression

Protocol biopsies after renal transplantation are useful in detecting subclinical rejection. In earlier studies, the incidence of subclinical rejection was high among renal transplant recipients on a cyclosporine-based immunosuppression. However, recent data show that subclinical rejection is low under tacrolimus-based immunosuppression. This study evaluates the utility of 6-month protocol biopsy in renal transplant recipients under induction with rabbit antithymocyte globulin and maintenance immunosuppression with tacrolimus, mycophenolate mofetil (MMF) and corticosteroids. 6-month protocol biopsies on 40 transplant recipients were analyzed for borderline and subclinical rejections. Allograft injury at biopsy was evaluated using the chronic allograft damage index score system (CADI) and was compared with initial scores obtained at implantation. Borderline rejection was detected in 1 out of 40 patients. No case of subclinical rejection was detected at protocol biopsy. In 31 patients with corresponding implantation biopsies, mean CADI score increased from 1.1 +/- 1.4 to 2.8 +/- 2.1 at 6 months despite stable graft function. In the subgroup of patients with a 6-month CADI score of 2 or less (n = 11), graft function remained stable at 12 months post transplant (65.3 +/- 16.9 ml/min/1.73 m2 at 6 months vs. 65.2 +/- 16.7 ml/min/1.73 m2 at 12 months, p = 0.96). In contrast, allograft function declined significantly at 12 months in those with a 6-month CADI score of > 2 (n = 20) (64.3 +/- 13.5 ml/min/1.73 m2 at 6 months vs. 51 +/- 9.8 ml/min/1.73 m2 at 12 months, p = 0.0006). While the incidence of borderline and subclinical is low under antilymphocyte antibody induction and tacrolimus-based immunosuppression, chronic allograft damage is highly prevalent at 6 months post transplantation. Our findings suggest that protocol biopsies under current immunosuppression may be more useful in the early detection of chronic allograft nephropathy (CAN).

Five-Year Study of Tacrolimus as Secondary Intervention Versus Continuation of Cyclosporine in Renal Transplant Patients at Risk for Chronic Renal Allograft Failure

Chronic allograft nephropathy is the most frequent cause of long-term kidney allograft loss. Studies are desperately needed to improve long-term survival. Tacrolimus has been associated with less rejection and better kidney function compared with cyclosporine in clinical trials. This study tested the hypothesis that conversion from cyclosporine to tacrolimus might improve long-term outcomes in patients with chronic allograft damage. In this multicenter Canadian clinical trial, cyclosporine-treated patients with biopsy-proven chronic allograft nephropathy and impaired renal function were randomly assigned (2:1) to convert to tacrolimus or continue on cyclosporine therapy. A total of 106 (70 tacrolimus and 36 cyclosporine treated) patients were followed-up for up to 5 years. The primary outcome was graft survival. In an intention to treat analysis, subsequent graft (73% vs. 81%, P=0.2835, log-rank test) and patient survival (91% vs. 92%, P=0.8668, log-rank test) were not different between the tacrolimus and cyclosporine groups, respectively. Changes in Chronic Allograft Damage Index scores on protocol biopsies from baseline to 3 years were not different (+0.4+/-1.8 vs. +1.3+/-3.2, P=0.5910, cyclosporine vs. tacrolimus, respectively). There were no significant differences in biopsy-proven acute rejection (6 [8.6%] vs. 2 [5.6%], tacrolimus vs. cyclosporine, respectively, P=0.5906). In this study, patients with chronic allograft damage converted from cyclosporine to tacrolimus demonstrated no apparent benefit.

FK778 ameliorates post-transplant expression of fibrogenic growth factors and development of chronic rejection changes in rat kidney allografts

Acute rejection is the major risk factor for the development of subsequent chronic allograft nephropathy (CAN), which is the primary reason for late allograft loss in kidney transplantation. Platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta) are the main mitogens mediating mesenchymal cell proliferation. Their early post-transplant induction may start cascades leading to the development of CAN. An immunosuppressive drug, FK778, inhibits de novo pyrimidine biosynthesis and several receptor tyrosine kinases (RTKs). Here we investigated its effects on acute and chronic rejection as well as post-transplant PDGF and TGF-beta expression in combination therapy with calcineurin inhibitors (CNIs). Kidney transplantations were performed from DA to WF rats. Syngenic DA-DA grafts were used as controls. Allografts were immunosuppressed with a combination of FK778 (10 mg/kg/day p.o.) and CsA (1.5 mg/kg/day s.c.) or tacrolimus (Tac) (1.5 mg/kg/day p.o.). Grafts were harvested 5 and 90 days after transplantation for histology and immunohistochemistry (PDGF-A, PDGF-B, PDGFR-alpha, PDGFR-beta, TGF-beta, TGF-betaR). The dose response of FK778 on acute rejection was studied with monotherapy of 5, 10 and 20 mg/kg/day. Chronic changes were scored according to the Chronic Allograft Damage Index (CADI). FK778 ameliorated the early post-transplant inflammatory response dose dependently. Additive effects were seen with FK778 and CNIs. Significantly lower CADI scores were seen in combination therapy of FK778 and CNIs compared with CNI monotherapies. FK778 also significantly reduced both early and late PDGF and TGF-beta expression when combined with CNIs. These results indicate that FK778 could prevent the development of CAN and be a promising therapy also in clinical kidney transplantation.

Vascular endothelial growth factor in chronic rat allograft nephropathy

Background Chronic allograft nephropathy (CAN) is a complex process of alloimmune responses and chronic inflammation leading to fibrosis and vasculopathy. We examined the biological role of proinflammatory vascular endothelial growth factor (VEGF) in a rat renal transplantation model of CAN. Methods Syngraft and allograft recipients were treated with a suboptimal dose of cyclosporine A which allows acute rejection and CAN to develop. Intragraft VEGF, VEGFR-1 and VEGFR-2 expressions were determined at 5, 14, 30 and 60 days. Protein tyrosine kinase inhibitor PTK787 was used to inhibit VEGFR activity. Results In nontransplanted kidneys and syngrafts, mild VEGF expression was observed in the glomeruli and tubuli. VEGFR-1 was detected in vascular structures and VEGFR-2 in glomeruli as well. In allografts, total intragraft VEGF expression and interstitial inflammatory cell VEGF expression were induced and correlated with the chronic allograft damage index (CADI) score. Total intragraft and interstitial inflammatory cell VEGFR-1 expression was induced and interstitial cell VEGFR-1 expression correlated with the CADI score. Blocking VEGF receptor signaling with PTK787 significantly reduced fibrosis and the CADI score, but did not affect early inflammation or VEGF, VEGFR-1, VEGFR-2 expressions compared to vehicle treated group. Conclusions Interstitial inflammatory cell VEGF and VEGFR-1 expressions are induced during the development of CAN. Increased VEGF activity may enhance the alloimmune induced inflammatory responses leading to fibrosis and CAN.

Sirolimus‐based triple immunosupression with antithymocyte globulin induction in expanded criteria donor kidney transplantation

Target of rapamycin inhibitors have presented similar graft and patient outcomes with no evidence of drug-induced nephrotoxicity when compared with calcineurin inhibitors. The principal aim of this study is to demonstrate the efficacy of sirolimus-based triple immunosuppression with antithymocyte globulin induction in expanded donor kidney transplantation. Twenty-seven primary expanded criteria donor kidney transplant recipients were recruited. The severity of kidney damage was qualified by zero-hour biopsies. Protocol biopsies were performed at 1 year to assess the chronic allograft damage. Death, graft function, proteinuria and adverse events were systematically analysed during the study period. The mean follow up was 20.2 months. Patient and graft survival was 100% with a mean glomerular filtration rate (GFR) of 53.1+/-4.9 mL/min at last follow up. The cumulative incidence of acute rejection was 11% at the last follow up. At 1 year, mean creatinine, GFR and proteinuria were 1.84 mg/dL, 52.3 mL/min, 651.5 mg/day, respectively. Four patients required surgical intervention due to urinary complications and recovered successfully. Two patients developed acute graft dysfunction due to acute tubular necrosis which was presumably drug related. Ten patients developed relapsing urinary tract infections and three patients had pneumonia. No infectious death occurred throughout the study period. Baseline renal structure was preserved in 13 biopsies at 1 year post transplant. Five patients demonstrated progressive but mild tubular atrophy or interstitial fibrosis in their protocol biopsies. The mean chronic allograft damage index scores at baseline and at 1 year from biopsy were 2.57+/-0.23 and 2.83+/-0.23, respectively (P=0.046). Low-dose sirolimus-based triple immunosuppression with antibody induction offered a safe clinical outcome in expanded criteria donor kidneys with the achievement of stable renal function and favourable recipient outcomes throughout the short term. However, mild progression of histological damage and increased risk of bacterial infection are a major concern. Additionally, the benefit (if any) of the low acute rejection rate on long-term graft outcome is still undetermined.

Timing and value of protocol biopsies in well-matched kidney transplant recipients – a clinical and histopathologic analysis

The role and timing of protocol biopsies after kidney transplantation are controversial. We changed our protocol biopsy policy and compared the predictive value of biopsies at different time-points. Protocol biopsies at 6 months (n = 45) were obtained during 2001-2004, and at 3 and 12 months from 2004 (n = 41). Donor biopsy was available from 70 patients. Histopathologic changes were described with chronic allograft damage index (CADI) and Banff 1997. Follow-up was for 18 months. Chronic allograft nephropathy (CAN) was present in 12%, 51%, and 34% and borderline or subclinical rejection in 9.8%, 8.9%, and 7.3% of patients at 3, 6, and 12 months. CAN at 6 and 12 months was associated with reduced graft function (P = 0.001). Semiquantitative CADI scores at all time-points significantly correlated with glomerular filtration rate (GFR) at 18 months. Strongest correlation existed with CADI at 12 months (P < 0.001). Change in CADI between 0-6 and 0-12 months, but not between 0-3 and 3-12 months, correlated with GFR at 18 months (P = 0.03, P = 0.01). Subclinical rejections were rare and chronic changes mild at 3 months. In our well-matched population, the predictive value of a biopsy at 3 months was inferior to biopsies at 6 or 12 months, both of which were effective in predicting long-term graft function.

Histologic and Clinical Findings in Living Donor Allografts with Long-Term Stable Function

Background/Aims: Protocol biopsy is an important strategy which assesses the histological changes that can occur in the renal allograft and adversely affect its outcome. We aimed to evaluate histological changes in long-term living donor transplants. Methods: Elective biopsies were done for 120 live donor renal transplant recipients with well-functioning grafts and no rejection history at least 1 year or more after transplant. All patients had serum creatinine levels <2 mg/dl. The histopathological findings using the chronic allograft damage index score were correlated with different clinical and immunological parameters. Results: Chronic tubulointerstitial fibrosis was the most prevalent finding (85% of cases), mostly of mild degree. Normal biopsies were reported in only 7.5% of cases, whereas chronic cyclosporine nephrotoxicity was detected in 5.8% of biopsies. Posttransplant hypertension was significantly correlated with glomerulosclerosis, and posttransplant diabetes with glomerulosclerosis, mesangial matrix increase, tubular atrophy and interstitial fibrosis. The main risk factors associated with a high chronic allograft damage index score were DR mismatching, posttransplant diabetes and time of biopsy. All histopathological changes increased with advancing donor age and declining graft function. Conclusion: Elective biopsies showed that histopathological findings do exist even with stable renal function that may pave the way for predicting long-term graft outcome.

Pathology and pathophysiology of chronic rejection

Purpose of review We summarize and update the histology and pathogenesis of chronic human renal allograft rejection. Particularly, we focus on recent biopsy-controlled clinical studies to prevent the process. Recent findings Chronic rejection is a clinical and a histological diagnosis, defined as ‘gradual deterioration in graft function in the absence of any other disease and with necessary graft histology to confirm the diagnosis’. The histological features may be explained as ‘response to injury’. In a multicenter study patients were initially immunosuppressed with calcineurin inhibitor, mammalian target for rapamycin inhibitor and steroids, and randomized at 3 months to continue with the treatment or have the calcineurin inhibitor withdrawn. The histological chronic allograft damage index score and transplant function were significantly better in the latter group 3 years later. In a single center study, basiliximab, mycophenolate and steroid-treated patients were randomized at transplantation for mammalian target for rapamycin inhibitor or calcineurin inhibitor. The chronic Banff score and transplant function were significantly better in the former group 2 years later. Summary Chronic rejection has been considered irreversible and the pathophysiology is still incompletely known. With proper use of mammalian target for rapamycin inhibitors, however, acting both as immunosuppressive and vasculoprotective compounds, the histological changes and decline in function may be reduced.