Chronic Renal Rejection Research Articles

Application value of shear-wave elastography combined with monochrome superb microvascular imaging in renal allograft chronic rejection.

Conventional ultrasound (US), which include gray scale US and Doppler US, is the first-line imaging modality for the evaluation of renal allograft; however, conventional US indicators have limitations. To explore the application value of shear-wave elastography (SWE) combined with monochrome superb microvascular imaging (mSMI) in renal allograft chronic rejection (CR). From November 2021 to February 2022 in the Lanzhou University Second Hospital, the US features of 54 patients with renal allograft were retrospectively analyzed. Patients were categorized into two groups: stable group(n = 44) and CR group(n = 10), with clinical diagnosis as reference standard. The vascular index (VI) on mSMI and parenchymal stiffness were measured in the middle cortex of all renal allografts and receiver operating characteristic (ROC) curves were drawn to evaluate the feasibility of differentiation. Statistically significant US features and biochemical indicators such as creatinine were scored, and the results of the scores were analyzed by ROC curve. The VI on mSMI of the stable group (49.5±2.0) was significantly greater than that of the CR group (33.8±5.9) (P = 0.028). There was a statistically significant difference in parenchymal stiffness between stable group (16.2kPa±1.2) and CR group (33.9kPa±6.6) (P = 0.027). The sensitivity was 90% and specificity was 81.8% of the scores in the differentiation of stable group from CR group (cut-off value, 2; P = 0.000). SWE combined with mSMI may help differentiate stable renal allograft from renal allograft CR and have the potential application value in the diagnosis of renal allograft CR.

Визначення рівня субпопуляцій лімфоцитів периферичної крові для діагностики хронічної реакції відторгнення ниркових алотрансплантатів

Актуальність. Однією з основних причин втрат ниркових алотрансплантатів (НАТ) у віддалені строки після трансплантації є прогресуюча хронічна дисфункція ниркового алотрансплантата (ХДНА), причиною розвитку якої в 20–60 % випадків є хронічне відторгнення (ХВ). Діагностика причин дисфункції трансплантата базується на морфологічному дослідженні, яке через інвазивність має ряд недоліків. Тому великий інтерес являє пошук неінвазивних методів діагностики стану НАТ, зокрема, дослідження клітинної ланки імунної відповіді. Мета. Дослідження відносної кількості субпопуляцій лімфоцитів периферичної крові та їх співвідношення в реципієнтів у віддаленому періоді після трансплантації нирки, оцінювання інформативності цих показників для діагностики ХВ НАТ. Матеріали та методи. Досліджено рівні субпопуляцій лімфоцитів (Т-клітини, Т-хелпери, Т-цитотоксичні, Т-активовані, T-NK-клітини, В-клітини, NK-клітини) у 43 реципієнтів НАТ залежно від перебігу віддаленого післяопераційного періоду та стану алотрансплантата через 1–9 років після алотрансплантації нирки, які були розподілені згідно з морфологічною верифікацією діагнозу на дві групи. Група 1 — 23 хворі із задовільною функцією НАТ без ознак відторгнення; група 2 — 20 хворих із ХДНА, обумовленою хронічною реакцією відторгнення (ХРВ) за даними пункційної біопсії. До контрольної групи увійшли 23 здорові донори, чиї показники становили референтний коридор. Результати. Дані аналізу показали підвищення середніх рівнів Т-активованих лімфоцитів у групах 1 та 2 щодо контрольної (8,9 ± 2,0; 8,4 ± 2,4; 6,8 ± 2,1 відповідно). Також виявлено зниження середніх показників рівнів T-NK-клітин (2,4 ± 2,0) та В-клітин (9,6 ± 2,0) у групі 2 щодо показників групи 1 (5,6 ± 1,8 та 12,4 ± 2,4 відповідно). Аналіз індексів співвідношення між окремими субпопуляційними одиницями лімфоцитів показав статистично вірогідну значущість різниці між індексом Т-клітини/T-NK-клітини (22,53 vs 46,89 в групах 1 та 2 відповідно; p < 0,05) та індексом Т-активовані/В-клітини (1,14 vs 4,17 в групах 1 та 2 відповідно; p < 0,05). При цьому чутливість індексу Т-клітини/T-NK-клітини становила 70 %, специфічність — 60 %. Чутливість індексу Т-активовані/В-клітини дорівнювала 55 %, специфічність — 50 %. Висновки. Зниження рівня T-NK-клітин ближче до нижнього порогового значення референтного коридора і, відповідно, співвідношення Т-клітини/T-NK-клітини в межах 44,49–49,29 (46,89 ± 2,40) у віддаленому післятрансплантаційному періоді може бути додатковою ознакою ХРВ як причини прогресуючої дисфункції НАТ.

Photopheresis Abates the Anti-HLA Antibody Titer and Renal Failure Progression in Chronic Antibody-Mediated Rejection.

Chronic renal antibody-mediated rejection (ABMR) is a common cause of allograft failure, but an effective therapy is not available. Extracorporeal photopheresis (ECP) has been proven successful in chronic lung and heart rejection, and graft versus host disease. The aim of this study was to evaluate the effectiveness of ECP in chronic ABMR patients. We investigated ECP treatment in 14 patients with biopsy-proven chronic ABMR and stage 2-3 chronic renal failure. The primary aim was to e valuate the eGFR lowering after 1 year of ECP therapy. The ECP responders (R) showed eGFR reduction greater than 20% vs the basal levels. We also evaluated the effectiveness of ECP on proteinuria, anti-HLA antibodies (HLAab), interleukin 6 (IL-6) serum levels, and CD3, CD4, CD8, CD19, NK, Treg and T helper 17 (Th17) circulating cells. Three patients dropped out of the study. The R patients were eight (72.7%) out of the 11 remaining patients. Because ECP was not associated with any adverse reaction, the R patients continued such treatment for up to 3 years, showing a persisting eGFR stabilization. Twenty four hour proteinuria did not increase in the R patients over the follow-up when compared to the non-responder patients (NR). In the R patients, the HLAab levels were reduced and completely cleared in six out of eight patients when compared with the NR patients. The NR HLAab levels also increased after the discontinuation of the ECP. The ECP in the R patients showed a decrease in CD3, CD4, CD8, CD19, and NK circulating cells. The ECP treatment in the R patients also induced Tregs and Th17 cell increases, and a decrease of the IL-6 serum levels. ECP abates the HLAab titer and renal failure progression in patients with chronic renal ABMR, modulating the immune cellular and humoral responses.

Automated mononuclear cell collection: a feasibility study employing a new software for extracorporeal photopheresis

Very recently, Fresenius Kabi, improved the software (autoMNC lymphocytes, SW 04.03.08) for mononuclear cells (MNCs) collection with the aim to ameliorate the quality of harvest, employing the automated autoMNC lymphocytes software SW 04.03.09. Herein, we report the results of an observational study evaluating the feasibility of MNCs collection in patients undergoing extracorporeal photopheresis (ECP) at our centre, using the new COM.TEC software 04.03.08c for MNC collection, afterwards integrated in the software 04.03.09, available on the market since November 2018. Thirty adult patients (21 males and 9 females) with GvHD, Chronic Lung Allograft Dysfunction or renal rejection, were consecutively enrolled to undergo 1 ECP procedure by the offline technique, according to our internal protocol, processing 1·5 blood volumes. Feasibility of collection was defined as: Hct in collection bag ≤5%, MNCs purity (percentage of MNCs/bag) ≥80%, MNCs collection efficiency (CE2) ≥60%, patient's platelet depletion ≤50%. Thirty ECP procedures were evaluated. Feasibility (defined by the four parameters previously described) of MNCs collection was observed in 1 out of the 30 harvests analysed. Median Hct in the product was 3·45% (IQR: 2·6-5·0), and median MNCs purity was 97·2% (IQR 89·1-98·6). Median CE2 for MNCs was 21·4% (IQR: 11·9-41·2), and median patient's platelet depletion was 36·2% (IQR 21·9-51·4). The autoMNC lymphocytes software SW 04.03.08c for MNCs collection in ECP setting demonstrated to collect a good quality product in terms of purity and RBC contamination even if the collection efficiency and platelet contamination must be improved.

Current pathological perspectives on chronic rejection in renal allografts.

Chronic rejection in renal transplantation clinically manifests as slow deterioration in allograft function and is a major contributor of late renal graft loss. Most cases of chronic rejection involve chronic antibody-mediated rejection (ABMR) triggered by the interaction of donor-specific alloantibodies with endothelial cells of the microcirculation. The evolution of the Banff classification involved a major revision of the ABMR criteria during the 2000s and led to the inclusion of detailed pathological characteristics of chronic ABMR in the 2013 Banff scheme, including microcirculation damage observed as newly formed basement membranes and arterial fibrous intimal proliferation. Inflammation of microvasculature including glomeruli and/or peritubular capillaries is also seen in substantial cases of chronic ABMR, defined as chronic active ABMR. Chronic active T cell-mediated rejection (TCMR) results from chronic T cell-mediated injury involving renal arteries but is less characterized under the current Banff classification, mainly due to the expanding histological criteria of chronic active ABMR. Characteristics shared by these two chronic rejection types can potentially cause diagnostic confusion. Hence, the diagnostic criteria or categories of chronic renal rejection require amendment of the current Banff classification. Assessment of rejection cases with molecular phenotyping advanced the mechanistic understanding of various dysfunctions in renal allograft, including ABMR and TCMR. Identification of disease-specific changes in gene expression by immunohistological studies, especially in chronic ABMR, has already been validated by several studies, warranting potential application to the pathological diagnostic process. This review provides an overview of current pathological perspectives on chronic rejection of renal allografts and future directions.

A chronic renal rejection model with a fully MHC-mismatched rat strain combination under immunosuppressive therapy

BackgroundThe Fischer-to-Lewis (LEW) rat model of kidney transplantation is a widely accepted and well-characterized model of chronic rejection. In contrast to transplantation in a clinical setting, however, the absence of treatment with immunosuppressants and only minor mismatch of major histocompatibility complexes (MHCs) are critical discrepancies. Here, we established a rat model of chronic rejection using fully MHC-mismatched strains in which kidney disease progresses even under immunosuppressive therapy. MethodsLEW (RT1l) rats were used as donors and Brown Norway (BN, RT1n) rats as recipients. Intramuscular administration of 0.1mg/kg of tacrolimus was initiated on the day of transplantation. Post-transplantation, this dose was maintained until Day 9, suspended until Day 28 and then resumed from Day 29. Renal function, histopathology, and levels of donor-specific antibody (DSA) and several biomarkers of renal injury were assessed. ResultsOn Day 91 post-transplantation, recipients received tacrolimus treatment with short-term suspension exhibited reduced renal function and changes in histology. Those were characteristics of chronic rejection including glomerulosclerosis, interstitial fibrosis, and tubular atrophy in human transplantation recipients. Urinary protein excretion increased in a linear fashion, and elevated levels of several biomarkers of renal injury and DSA were observed even under administration of an immunosuppressant. ConclusionsWe established an allograft rejection model with impaired renal function and typical histopathological changes of chronic rejection in fully MHC-mismatched rats by controlling administration of an immunosuppressant. These findings suggest that this model more accurately reflects transplantation in a clinical setting than existing models and enables the evaluation of therapeutic agents.

STUDY THE STATUS USING IMMUNOSUPRESSANTS, SIDE EFFECTS OF IMMUNOSUPRESSANTS AND COMPLICATIONS ON RENAL TRANSPLATATION PATIENTS

Renal transplantation is the most effective therapy in treatment the end stage renal disease. Donated kidney can be transplanted from living donors or brain dead donors renal transplantation reduces the mortality and life quality versus hemodialysis. HLA gene is the most basic examination in renal transplantation. Objectives: to study the status of using the immunosupressants, side effects of immunosuppressants and complications on renal transplantation patients. Materials and Methods: 66 patients at Hue Centre Hospital from 11/2013 - 9/2014 . A Cross-sectional and prospective study. Results and conclusions: 3 patients had acute renal rejection and 4 patients had chronic renal rejection. The complications in the groups transphlanted over 1 years were diabietes, diarrhea, varicella, thrombopenia. Hyperuricemia was 39.4%, drugs hepatitis was 12.1%. After renal transplantation, were 13.6% had urinary infections, no case of heart failure was domanted. Key words: renal transplantation, immunosuppressants, complications.

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Aim Renal allograft failure accounts for nearly 30 percent of patients awaiting renal transplantation. Our aim was to determine if key proteins associated with fibrosis are targets for immune response leading to allograft rejection and may have promise as diagnostic and/or prognostic biomarkers. Methods Type II epithelial-to-mesenchymal transition (EMT) is reported to be involved in renal interstitial fibrosis. Five custom ‘direct-capture’ assays were developed on the Luminex immunobead platform for putative EMT autoantigens, including vimentin, beta catenin, p53, phosphoglycerate mutase and survivin. Extensive analytical validation for both single- and multi-plex assays was performed to establish the standard test performance characteristics. The diagnostic value of these assays were evaluated using diagnostic serum samples from cases of chronic renal allograph rejection (n = 25) and age-matched controls (n = 21). All measurements were performed on a Luminex FlexMAP 3D system equipped with xPONENT v3.2 and data analyzed using IBM SPSS v19.0. Results All analytical validations showed excellent accuracy and inter- and intra-batch precision across wide ranges of quantitation (1.5 ng/mL – 4 μ g/mL). Cross reactivity of P53and PGAM within the 5-plex assay necessitated a 3- and 2- plex assay configuration to resolve these issues. Validated multiplexed assays were then used to establish background levels of autoantibodies in an age-matched cohort prior to evaluation of autoantibody titre in the cases of chronic allograph rejection. The Mann-Whitney U test found that autoantibodies against P53 and vimentin were highly significant (p Conclusions Our findings support the idea that type II EMT may be highly associated with autoimmunity in chronic allograph rejection.

Reactivation of intestinal CMV in a renal transplant patient after 10 years from the transplant

Introduction.We analyzed the clinical case of a 51 years old man, kidney transplanted on December 2002. On April 2011, he had acute rectal bleeding, renal chronic rejection (creatinine 2.9 mg/dl), Hgb 8.7 g/dl, positive anti-CMV antibodies (IgG). A colonoscopy showed diverticulosis of the rectum associated with deepithelialisation. The patient was treated with maintenance immunosuppressive post-transplant therapy. On June 2011, the colonoscopy showed a stenosing lesion of the sigmoid colon, and blood sampling and intestinal biopsy were performed to search Cytomegalovirus (CMV) DNA by PCR. Methods. The presence of CMV-DNA was sought by automatic extractor QIACUBE, using QIAamp DNA BLOOD Mini Kit (Qiagen) for whole blood and QIAamp DNA Mini Kit (Qiagen) for biopsy.The extracted DNA was then amplified by Real Time PCR using Q-CMV RealTime Complete Kit (Nanogen), on instrument Applied Biosystems 7300. Results. At disease onset the viral load in whole blood was 208000 Geq/ml, and biopsy was positive. Antiviral therapy with Ganciclovir led to the negativity of the viral load and remission of symptoms. Conclusions. The clinical case described presented a reactivation of CMV infection in the intestine after more than 10 years from kidney transplantation, while the highest incidence of CMV reactivation usually occurs during the first year. In our opinion, the reactivation can be traced to long-term immunosuppressive therapy (maintenance posttransplant therapy) in combination with a state of inflammation of the intestinal mucosa. In fact, patients with IBD treated with steroid drugs, in particular the group of refractory to therapy and thus have a recovery of the inflammatory process, are exposed to reactivation of CMV with intestinal localization.

The influence of immunosuppressive drugs on vascular endothelial growth factor production in relation to VEGF -1154 g and -2578 C genotypes.

The pathogenesis of many diseases is correlated to irregularity in vascular endothelial growth factor (VEGF) expression. RESULTS from several association studies show that variation in the level of VEGF expression is related to polymorphic sequences within the VEGF gene. Additionally, there are many studies showing that some gene polymorphisms significantly influence the pharmacokinetics of immunosuppressive drugs. The aim of this study was to determine the influence of immunosuppressive drugs on VEGF production in individuals with different VEGF genotypes. ARMS-PCR was used to genotype VEGF polymorphisms at positions -1154 and -2578 within the promoter of VEGF gene. A VEGF-specific ELISA was used to determine the influence of immunosuppressive drugs on VEGF production in PBMCs of individuals with different VEGF genotypes. Suppressive effect of mycophenolic acid was observed just in individuals with GG -1154/CC -2578, GG -1154/CA -2578 and GA -1154/CC -2578 haplotypes. Additionally, VEGF was significantly suppressed in all individuals after treatment with rapamycin except those who had AA -1154/CA -2578 and AA -1154/AA -2578 VEGF genotype combinations. RESULTS of a recent study revealed that MMF treatment might be effective in preventing chronic renal rejection only in recipients with IL-10 high producer genotype. Additionally result of another study showed that CYP3A5 genotype markedly influences the pharmacokinetics of rapamycin in kidney transplant recipients. Therefore with regard to our results, different suppressive effect of mycophenolic acid and rapamycin on VEGF production might also be dependent on VEGF genotype.

Expression of Fractalkine, CX3CR1, and Vascular Endothelial Growth Factor in Human Chronic Renal Allograft Rejection

Aim Fractalkine/CX3CR1 system may contribute to the pathogenesis of renal allograft chronic rejection (CR). Vascular endothelial growth factor (VEGF) is an endothelial mitogen, which shows increased expression in inflammation and vasculopathy. This study sought describe the expression and distribution of Fractalkine/CX3CR1 and VEGF, and their relationship to human renal allograft CR. Methods Renal tissue from 10 patients with CR was examined for Fractalkine/CX3CR1 and VEGF protein by immunohistochemistry for comparison with patients displaying hyperacute rejection ( n = 10), acute rejection ( n = 10), and normal kidneys ( n = 10). All patients were selected based upon histologically proven diagnoses between 1992 and 2003. Results Immunohistochemistry revealed that Fractalkine/CX3CR1 were mostly expressed in the tubulointerstitium and tubular epithelial cell basolateral membrane. Some vessels showed positive staining for Fractalkine/CX3CR1 as well as occasionally glomerular parietal wall cells. Among the CR group, VEGF was mostly expressed in tubular epithelium and the tubulointerstitium. A proportion of glomeruli and vessels had positive staining for VEGF, which was up-regulated most strikingly in the interstitial compartment in CR. There was markedly increased expression of Fractalkine/CX3CR1 and VEGF protein in the interstitium of the CR compared with other groups ( P < .05). VEGF colocalized with the expression of Fractalkine/CX3CR1. Conclusion Fractalkine/CX3CR1 and VEGF may play an important role in the development of interstitial fibrosis via mononuclear cell-induced cytokine production and myofibroblast stimulation in CR. Further studies are necessary to identify the role in the pathogenesis of CR.

Extracellular matrix proteins, proteolytic enzymes, and TGF-Beta1 in the renal arterial wall of chronically rejected renal allografts

Chronic rejection (CR) is the leading cause of long-term failure of transplanted kidneys. The vascular hallmark is intimal hyperplasia, accompanied by macrophage, foam cell, and T-cell infiltration. Intimal thickening results from the migration and proliferation of smooth muscle cells and increased deposits of extracellular matrix (ECM) proteins, due to release of growth factors and cytokines as well as altered ECM protein turnover. We assesed the content of fibronectin (FN) and transforming growth factor-β1 (TGF-β1) as well as the activities of collagenase and cathepsin B and L in renal artery walls of chronically rejected human renal allografts. We investigated renal artery samples from 8 patients with CR undergoing graftectomy, 12 patients undergoing nephrectomy, and 7 organ donors. The results were related to the DNA content of homogenates. Cathepsin B and L activities were significantly higher among those with compared with donors ( P = .022). There was a trend toward higher collagenase activity in CR compared with donors and the nephrectomy group. TGF-β1 was significantly enhanced in CR compared with donors ( P = .010), and showed a trend toward higher concentrations in CR compared with the nephrectomy group. The trend was toward lower FN concentrations in CR compared with the nephrectomy group and toward higher concentrations compared with donors. Summarizing, renal CR is accompanied by enhanced proteinase activity, alterations of ECM proteins, and increased TGF-β1 in the renal artery wall. We conclude that ECM turnover and cytokines play an important role in neointimal formation and CR pathogenesis.

Immunotoxin-treated rhesus monkeys: a model for renal allograft chronic rejection.

Unlike acute and hyperacute rejection, chronic rejection (CR) still constitutes a poorly understood process. The onset is insidious, occurs in a period of months to years and, because the pathophysiology is not well understood, is untreatable. A reliable large-animal model for renal allograft CR is needed and has not been reported in the literature yet. CR biopsy changes were studied in major histocompatibility complex-mismatched renal allografts performed in nine rhesus monkeys that received CD3 T-lymphocyte depletion therapy with immunotoxin on the day of the transplantation (n=7) or 7 days before transplant (n=2). Mean graft survival time was 613.77 days. Biopsy changes of CR were identified as soon as 84 days after transplant (mean, 336 days; range, 84-896 days). Most of the experimental animals had severe interstitial fibrosis, tubular atrophy, chronic transplant glomerulopathy, and chronic vascular rejection changes at the time of necropsy. A significant positive correlation between the severity of CR and the degree of CD68+ macrophage infiltrate of renal parenchyma and the degree of anemia and serum creatinine level elevations were also observed. Our findings are similar to those seen in human renal chronic allograft nephropathy, but in contrast, our model excludes all the nonimmune factors associated with chronic allograft nephropathy, including donor disease, injury from prolonged preservation, drug toxicity, and underlying recipient disease. Immunotoxin-treated rhesus monkeys emerge as an outstanding animal model for assisting us in understanding the pathophysiology of CR.

Cardiovascular 24-h rhythms and renal excretory function in rats after allogeneic kidney transplantation.

We investigated long-term and circadian blood-pressure changes in a Fischer-->Lewis rat model of chronic renal allograft rejection. Ten days after allogeneic kidney transplantation, rats were equipped with telemetry transmitters for continuous monitoring of blood pressure. Urine was sampled 24, 96 and 180 days after kidney transplantation for measurement of renal protein loss and excretion of nitric oxide metabolites. Proteinuria increased with time after transplantation, while urinary excretion of nitric oxide metabolites declined. In five of six rats blood pressure remained in the normotensive range, and its 24-h pattern was preserved up to 6 months post-transplantation. One animal showed hypertensive blood pressure and a disturbed 24-h pattern with peak values during the rest period. In the post-mortem analysis this rat showed a hydronephrotic kidney graft. In conclusion, blood pressure and its 24-h pattern are preserved after successful allogeneic kidney transplantation in the rat.

Recipient age and weight affect chronic renal allograft rejection in rats.

Nephron doses and immune responses change with age. Therefore, age is a potential risk factor for graft survival after kidney transplantation. The aim of this study was to determine whether age-related differences are of importance for long-term outcomes after renal transplantation. Kidneys from Fisher 344 rats were orthotopically transplanted into nephrectomized Lewis rats. Kidneys were transplanted using donors and recipients of three age levels, i.e., young (8 wk of age), adult (16 wk of age), and old (40 wk of age). Rats were killed 24 wk after transplantation, and functional, morphologic, and molecular evaluations were performed. Recipient age, rather than donor age, determined graft survival rates. No significant correlation was observed between donor kidney weight on the day of transplantation and morphologic results. Advanced recipient age was associated with reduced creatinine clearance, more severe histologic injuries, including extended glomerular sclerosis, interstitial fibrosis, and vascular lesions, more pronounced cellular infiltration, and greater expression of transforming growth factor-beta and platelet-derived growth factor A and B chains. Although no significant correlation between donor age or kidney weight on the day of transplantation and morphologic results was observed, there was a significant correlation between recipient body weight on the day of transplantation and allograft injury. It is concluded that recipient age and weight affect chronic renal rejection. Renal allografts may benefit from young recipient age but may deteriorate in old recipients, suggesting effects of recipient functional demand on long-term outcomes.

Mast cell chymase expression and mast cell phenotypes in human rejected kidneys

Mast cells (MCs) are known to participate in various types of chronic disease, but their role in chronic renal rejection is poorly understood. Recently, distinct phenotypes of MCs have been described in humans by the demonstration of one protease, chymase. Hence, we questioned whether chymase in MCs could play a role in the pathogenesis of renal rejection in humans. We investigated MC chymase expression and MC phenotypes, using immunohistochemical single- and double-staining techniques, in nephrectomy (N = 13) and biopsy (N = 8) specimens of human rejected kidneys. Tissue chymase levels were determined by enzymatic assay for chymase activity. We also examined the association between MC chymase expression and the degree of interstitial fibrosis in these renal allografts. Based on chymase positivity, rejected kidneys were divided into two groups, a chymase-negative [Chy(-)] group and a chymase-positive [Chy(+)] group. Quantitative analysis showed that the number of chymase-positive MCs and tissue chymase levels were significantly higher in the Chy(+) group than in the Chy(-) group. Furthermore, the interstitial fibrotic area in the Chy(+) group was significantly larger than that in the Chy(-) group. Immunodouble staining analysis also demonstrated that a new MC phenotype, positive for chymase but negative for tryptase, was present in the human rejected kidney. These results show that increased expression of chymase in MCs is related to the severity of interstitial fibrosis in human rejected kidneys.

Is the proximal tubular cell a proinflammatory cell?

In the past few decades, accumulating evidence has been generated on the central role of the proximal tubular cell in renal injury and dysfunction, such as can be found in some patients with glomerular proteinuria and in chronic renal rejection or following ischaemic insult. Following initial injury or stimulation of the proximal tubular cells, various cascades of mediator systems can be activated leading, for example, to enhanced local production of complement, chemokines, cytokines and matrix components. The locally produced mediators subsequently can lead to amplification of injury either directly or indirectly by enhancement of influx of proinflammatory cells such as macrophages, polymorphonuclear leukocytes and T cells. The concerted production of cytokines and chemokines may tip the balance to a more proinflammatory pathway leading to irreversible interstitial injury of the kidney and loss of renal function.

RANTES and MCP-1 chemokine plasma levels in chronic renal transplant dysfunction and chronic renal failure

Objectives: Procedures to diagnose renal allograft rejection depend on detection of graft dysfunction due to the presence of mononuclear leukocytic infiltrates. Design and methods: In our study, we pursued an immunodiagnostic approach utilizing an ELISA method on plasma samples to monitor patients waiting to undergo transplantation in order to evidence prognostic developments in renal transplantation and, at least, to diagnose renal chronic transplant dysfunction. We analyzed blood levels of two chemokines, RANTES and MCP-1, which are normally overexpressed locally in renal chronic rejection. Results: Our results showed that patients affected by chronic renal failure (and waiting for kidney transplant), as well as kidney-grafted patients affected by chronic transplant dysfunction, had plasma levels of RANTES significantly higher than those of controls (patients without acute or chronic pathologies). Conclusions: Our data suggest a simple method to evaluate the plasmatic presence of RANTES, which could be involved in long-term kidney graft failure.

AFRICAN-AMERICAN COMPARED TO CAUCASIAN RESPONSE TO CORTICOSTEROID WITHDRAWAL FOLLOWING TACROLIMUS THERAPY FOR REFRACTORY RENAL REJECTION

625 The results of corticosteroid withdrawal (CSWD) following tacrolimus therapy for refractory acute renal allograft rejection (RARAR) have not been defined in prospective clinical trials. The results of a prospective trial of CSWD after tacrolimus therapy for RARAR are presented. Methods: Between Oct '93 and Oct '98, forty-three patients, twenty-nine African-American (AA) and fourteen Caucasian (CA) patients, were enrolled in a trial of tacrolimus therapy for RARAR that included a prospective CSWD protocol. RARAR was defined as biopsy proven acute rejection (by Banff criteria) occurring during or after rejection therapy with an antilymphocyte preparation. Patients with chronic rejection (by Banff criteria) were excluded. Statistical analysis was performed using Z scores. Results: Mean follow-up for the AA and CA populations were 29 and 38 months. Corticosteroids were successfully withdrawn in 9/29 (31%) for the AA group and 12/14 (86%) in the CA group. Eleven grafts were lost in the AA group to acute rejection 5/11 (1 lost to biopsy bleed, 1 to pt noncompliance) and chronic rejection 6/11 (2 lost to pt noncompliance). Graft loss in the CA group was only secondary to chronic renal rejection (2/14). The overall incidence of acute rejection was 15/29 (52%) for the AA group and 4/14 (29%) for the CA group. The AA patients experienced a significantly lower graft survival at both 2 years (54% vs. 80%) and 3 years (40% vs. 79%). (p=0.03). Chronic rejection was diagnosed equally in both groups, AA 4/29 (14%) and CA 2/14 (14%). No significant differences in weight, white blood cell count or the incidence of new onset diabetes between groups were noted. Initiation or increased anti-hypertensive therapy was required in 28% of AA patients and 21% of the CA patients. (p=NS). Tacrolimus dose, tacrolimus levels, azathioprine dosing, and mycophenolate mofetil dosing were not different between groups over the study period. Serum creatinine and creatinine clearances were not significantly different at three years. Conclusions: CSWD can be performed following tacrolimus therapy for RARAR with acceptable long-term recurrent rejection and graft survival rates in caucasian patients. African-American patients, however, experience higher rates of recurrent rejection and lower long-term graft survival.

Activation of the serine proteinase system in chronic kidney rejection.

Activation of the serine proteinase system is an important mechanism that contributes to tissue remodeling. In the present study, we analyzed the expression of urokinase plasminogen activator (uPA), urokinase plasminogen activator receptor (uPAR), and plasminogen activator inhibitor type 1 (PAI-1) in samples of chronically rejected human kidneys. Using Northern blot analysis, immunohistochemistry, and a uPA activity assay, specimens from 10 chronically rejected kidneys and 10 normal kidney samples were analyzed. By Northern blot analysis, the expression of uPAR and PAI-1 mRNA was 2.9-fold (P<0.05) and 2.3-fold (P<0.05) increased in chronically rejected kidney samples, respectively, compared with normal controls. In contrast, uPA mRNA levels in chronically rejected kidneys were comparable to those in the normal controls. Immunohistochemical analysis in normal kidneys showed weak immunostaining of uPA, moderate to intense uPAR and PAI-1 immunostaining in proximal tubules, and moderate immunostaining in distal tubules, but no signal in the glomeruli or cortical vessels. A similar staining pattern was found in the distal and proximal tubules in rejected kidney tissue samples. However, in the rejected kidneys, the number of tubules was markedly reduced. In addition, within the glomeruli of rejected kidney samples, there was positive immunostaining for uPA, uPAR, and PAI-1 in the mesangial cells, but negative staining in most of the endothelial cells, whereas the normal kidneys revealed no immunoreactivity in these structures. The demonstrated up-regulation of uPA/uPAR/PAI-1 in chronic renal rejection is consistent with the plasminogen/plasmin system contributing to tissue remodeling in this disorder. These factors might activate latent transforming growth factor-betas, which have been reported to be enhanced in this disorder, contributing to the generation of the extracellular matrix.