Renal Allograft Dysfunction Research Articles

Feasibility of diagnosing renal allograft dysfunction by oligonucleotide array: Gene expression profile correlates with histopathology

Background Effective non-invasive monitoring method to tell histopathology is a big challenge in renal transplantation. Methods We used 70-mer long oligonucleotide array with 449 immune related genes to determine gene expression profiles of peripheral blood mononuclear cells (PBMCs) under different immune status including stable renal function (TX), acute tubular necrosis (ATN), biopsy conformed acute rejection (AR), clinical rejection with pathology of borderline changes (BL), clinical rejection without biopsy proven/presumed rejection (PR) and renal dysfunction without rejection (NR). Results Distinct molecular expression signatures in each group were found to correlate with histopathology. And we concluded that B cell chemokine CXCL13 and mast cell may play a role in renal allograft rejection through significant difference analysis and functional pathway analysis. Conclusions It provides a potential non-invasive method for monitoring renal allograft function and immune status of renal transplant recipients.

A prospective, open-label, observational clinical cohort study of the association between delayed renal allograft function, tacrolimus exposure, and CYP3A5 genotype in adult recipients

Background: Tacrolimus, a calcineurin inhibitor with a macrolide lactone structure, is currently used as a cornerstone immunosuppressive drug in solid organ transplantation. It is metabolized by hepatic and intestinal cytochrome P450 (CYP) 3A4/3A5 enzymes and is a substrate for P-glycoprotein (ABCB1). The disposition of tacrolimus might be influenced by severe renal allograft dysfunction (eg, in cases of delayed graft function [DGF]). New-onset diabetes after transplantation (NODAT) is a known adverse effect of tacrolimus therapy and has been associated with DGF. Objectives: The impact of DGF on tacrolimus C min and dose requirements was evaluated in renal transplant recipients in the first postoperative week. The effects of the CYP3A5*3 A6986G polymorphism on initial mean tacrolimus C min and dose requirements in the presence and absence of DGF were assessed. This study also tested the hypothesis that if DGF influences early tacrolimus exposure, this would lead to a higher risk for NODAT (defined as the need for glucose-lowering medication for an uninterrupted period of ≥26 weeks). Methods: This prospective, open-label, observational clinical cohort study enrolled renal allograft recipients aged ≥18 years. Tacrolimus was administered as an oral loading dose of 0.2 mg/kg/d and adjusted to achieve a target mean daily tacrolimus C min between 12 and 15 ng/mL. C min values and oral dose requirements in the first postoperative week were compared between patients with and without DGF. Patients were genotyped for the CYP3A4*1B -290A>G, CYP3A5*3 A6986G, ABCB1 Exon26 C3435T, ABCB1 Exon21 G2677T, and ABCB1 Exon21 G2677A single nucleotide polymorphisms. NODAT that occurred within the first 12 weeks after transplantation was confirmed using an oral glucose tolerance test. Results: A total of 304 patients were enrolled (184 men, 120 women; mean [SD] age, 52.9 [14.1] years). Through day 3 after transplantation, mean (SD) 12-hour tacrolimus C min values were significantly higher in recipients experiencing DGF despite identical loading doses of 0.2 mg/kg. Mean tacrolimus dose requirements were significantly lower in patients with DGF during the first week. After recovery of DGF, mean tacrolimus dose requirements were not significantly different between recipients with and without DGF. In homozygous CYP3A5*3 carriers (n = 252), mean (SD) tacrolimus dose requirements remained significantly lower during DGF, while in CYP3A5*1 carriers with DGF (n = 52), lower mean dose requirements were observed only after postoperative day 4. The proportion of patients in whom NODAT developed was significantly greater in patients with DGF and tacrolimus C min >15 ng/mL on the first day after transplantation (27.2%) compared with recipients who remained free of DGF and had Cmin ≤15 ng/mL on day 1 (6.5%) ( P = 0.016). On logistic regression analysis, greater recipient age (odds ratio [OR] = 1.044; 95% CI, 1.009–1.080), higher tacrolimus C min on day 1 (OR = 1.048; 95% CI, 1.017–1.080), and DGF (OR = 2.968; 95% CI, 1.107–7.959) were associated with an increased risk for NODAT. Conclusion: In this open-label, observational study, DGF was associated with higher initial mean tacrolimus Cmin values and lower daily dose requirements predominantly in CYP3A5 nonexpressers.

Validation of Noninvasive Diagnosis of BK Virus Nephropathy and Identification of Prognostic Biomarkers

BK virus nephropathy (BKVN) may cause renal allograft dysfunction and failure. The gold standard test is kidney biopsy, which is invasive and costly. A noninvasive, accurate biomarker for diagnosis of BKVN and prognostication of allograft function after BKVN infection may improve allograft survival. We tested the diagnostic accuracy of our previously reported cutoff value of 6.5x10(5) BKV viral capsid protein 1 (VP-1) mRNA/ng RNA in urinary cells (Ding et al., Transplantation 2002; 74: 987) using an independent cohort (n=89). We also examined whether urinary cell mRNA profiles obtained at the time of BKVN diagnosis identified patients at risk of subsequent decline in graft function. BKVN was accurately diagnosed (sensitivity of 100% and specificity of 97%) using our previously reported cutoff value. Levels of granzyme B (GB) mRNA (P=0.002) and proteinase inhibitor (PI)-9 mRNA (P=0.01) in urinary cells were higher in BKVN patients with a subsequent decline in renal function (n=8) compared with patients with stable function (n=10), and were positively associated (GB, P=0.01; PI-9, P=0.04) with rise in serum creatinine from the time of BKVN diagnosis to 12 months after diagnosis. GB levels in the BKVN patients with a decline in renal function were similar to those in the acute rejection group (n=11, P>0.05), but higher than the normal biopsy group (n=36, P<0.001); levels in BKVN patients with stable function were lower than those in the acute rejection group (P<0.01) and not significantly different from the normal biopsy group (P>0.05). Noninvasive diagnosis of BKVN and prognostication of renal allograft function after BKVN diagnosis are feasible by measurement of transcripts for BKV viral capsid protein 1 (VP-1), GB, and PI-9 in urine.

Gene Polymorphisms in Renal Transplantation

A vast majority of gene polymorphism studies in renal transplantation focus on short-term outcomes such as acute rejection. The main purpose of this article is to review the literature available and studies that have examined the association between the gene polymorphisms and long-term renal allograft functions. In this review, we focus on commonly reported genes in the renin angiotensin system, transforming growth factor-beta gene, and metalloproteinases on the incidence and progression of chronic renal allograft dysfunction.

Glomerular damage as a predictor of renal allograft loss

Interstitial fibrosis and tubular atrophy (IF/TA) are the most common cause of renal graft failure. Chronic transplant glomerulopathy (CTG) is present in approximately 1.5-3.0% of all renal grafts. We retrospectively studied the contribution of CTG and recurrent post-transplant glomerulopathies (RGN) to graft loss. We analyzed 123 patients with chronic renal allograft dysfunction and divided them into three groups: CTG (N = 37), RGN (N = 21), and IF/TA (N = 65). Demographic data were analyzed and the variables related to graft function identified by statistical methods. CTG had a significantly lower allograft survival than IF/TA. In a multivariate analysis, protective factors for allograft outcomes were: use of angiotensin-converting enzyme inhibitor (ACEI; hazard ratio (HR) = 0.12, P = 0.001), mycophenolate mofetil (MMF; HR = 0.17, P = 0.026), hepatitis C virus (HR = 7.29, P = 0.003), delayed graft function (HR = 5.32, P = 0.016), serum creatinine > or =1.5 mg/dL at the 1st year post-transplant (HR = 0.20, P = 0.011), and proteinuria > or =0.5 g/24 h at the 1st year post-transplant (HR = 0.14, P = 0.004). The presence of glomerular damage is a risk factor for allograft loss (HR = 4.55, P = 0.015). The presence of some degree of chronic glomerular damage in addition to the diagnosis of IF/TA was the most important risk factor associated with allograft loss since it could indicate chronic active antibody-mediated rejection. ACEI and MMF were associated with better outcomes, indicating that they might improve graft survival.

Peroxisome Proliferator-Activated Receptor (PPAR)γ Can Inhibit Chronic Renal Allograft Damage

Chronic inflammation and fibrosis are the leading causes of chronic allograft failure. The nuclear receptor peroxisome proliferator-activated receptor (PPAR)gamma is a transcription factor known to have antidiabetogenic and immune effects, and PPARgamma forms obligate heterodimers with the retinoid X receptor (RXR). We have reported that a retinoic acid (RAR)/RXR-agonist can potently influence the course of renal chronic allograft dysfunction. In this study, in a Fischer to Lewis rat renal transplantation model, administration of the PPARgamma-agonist, rosiglitazone, independent of dose (3 or 30 mg/kgBW/day), lowered serum creatinine, albuminuria, and chronic allograft damage with a chronic vascular damage score as follows: 35.0 +/- 5.8 (controls) vs. 8.1 +/- 2.4 (low dose-Rosi; P < 0.05); chronic tubulointerstitial damage score: 13.6 +/- 1.8 (controls) vs. 2.6 +/- 0.4 (low dose-Rosi; P < 0.01). The deposition of extracellular matrix proteins (collagen, fibronectin, decorin) was strikingly lower. The expression of transforming growth factor-beta1 was inhibited, whereas that of bone morphogenic protein-7 (BMP-7) was increased. Intragraft mononuclear cells and activated fibroblast numbers were reduced by 50%. In addition, the migratory and proliferative activity of these cells was significantly inhibited in vitro. PPARgamma activation diminished the number of cells expressing the proinflammatory and fibrogenic proteoglycan biglycan. In macrophages its secretion was blocked by rosiglitazone in a predominantly PPARgamma-dependent manner. The combination of PPARgamma- and RAR/RXR-agonists resulted in additive effects in the inhibition of fibrosis. In summary, PPARgamma activation was potently immunosuppressive and antifibrotic in kidney allografts, and these effects were enhanced by a RAR/RXR-agonist.

ARFI-based tissue elasticity quantification in comparison to histology for the diagnosis of renal transplant fibrosis

Until recently clinical diagnosis of chronic renal allograft dysfunction could only be established invasively by renal biopsy. Given the risks of that procedure, a non-invasive, diagnostic test would be very advantageous. Novel ultrasound-based elasticity tools, using "Acoustic Radiation Force Impulse (ARFI)" technology are now available. Previously this technique has been utilised to quantify liver fibrosis. First results of these studies are promising. The purpose of our study was to investigate correlation between stiffness values obtained by ARFI-quantification and histological fibrosis score in renal transplants. We employed "Virtual Touch™ tissue quantification" (Siemens Acuson, S2000) to quantitatively measure tissue stiffness in the cortex of transplant kidneys. Eighteen patients were included in this prospective study, recording close temporal ARFI-quantification and fibrosis measurements. All patients undergoing renal transplant biopsy were examined with ARFI-quantification (15 measurements per transplant kidney). Resistive indices were also calculated from pulsed-wave Doppler ultrasound. Transplant biopsies were histologically evaluated by a reference nephropathologist and graded according to the percentage of fibrosis and to the BANFF-score. Due to the non-normal distribution of the data the Spearman-correlation-coefficient (rho) was used to assess the bivariate relationship of ARFI and fibrosis in the transplant kidney. There was a significant positive moderate correlation between mean ARFI-values and the grade of fibrosis (rho = +0.465; p = 0.026). This correlation was also valid for the mean ARFI-values and the BANFF-category (rho = +0.468; p = 0.025). There was no significant correlation between the mean ARFI-values and the resistive indices in the transplant kidney (rho = +0.034; p = 0.904). Nevertheless, a positive correlation between the mean RI-values of the kidney and the grade of fibrosis was established (rho = +0.563; p = 0.015). The mean values of ARFI measurements and the resistive indices are potentially independent explanation variables for evaluating the grade of fibrosis in transplant kidneys.

Invasive aspergillosis caused by Aspergillus terreus in a living donor liver transplant recipient successfully treated by caspofungin

Invasive aspergillosis is one of the most severe complications after liver transplantation characterised by early dissemination of disease and high mortality. Recent data show that the prognosis is diminishing even further when Aspergillus terreus, a strain resistant to standard treatment with amphotericin, is isolated. We report a high risk liver transplant recipient with multiple co-morbidities including renal failure and allograft dysfunction in whom pulmonary aspergillosis due to A. terreus was successfully treated by the echinocandin antifungal agent caspofungin.

Mycobacterium avium‐intracellulare‐associated acute interstitial nephritis: a rare cause of renal allograft dysfunction

Nontuberculous mycobacterium (NTM) infections are unusual in the renal transplant population. We present a case of disseminated Mycobacterium avium-intracellulare in a renal transplant recipient who was negative for human immunodeficiency virus infection. Our patient developed renal allograft dysfunction in the setting of disseminated disease and reduced immunosuppression. Transplant biopsy showed acute interstitial nephritis with granulomas and acid-fast bacilli. Acute renal failure resolved completely with further reductions in immunosuppression and anti-mycobacterial therapy. Our patient demonstrates the challenges in diagnosis and treatment of this rare infectious complication.

Interactions between Antiinfective Agents and Immunosuppressants

Interactions between Antiinfective Agents and Immunosuppressants

Determinants of Resistive Index Shortly after Transplantation: Independent Relationship with Delayed Graft Function

Measurement of the vascular resistive index (RI) by Doppler ultrasonography has been proposed as a non-invasive method to evaluate renal allograft dysfunction, but there are conflicting reports about its clinical utility. The aim of our study was to analyse the donor and recipient characteristics related to RI measured at days 2 and 3 after renal transplantation and the relationship between RI and allograft outcome. RI was measured by Doppler ultrasonography in 333 patients at days 2 or 3 post-transplantation. Donor and recipient variables and allograft outcome were collected from a prospectively maintained institutional database. In patients with RI higher than 0.7, donor age, recipient age, duration of renal replacement therapy, incidence of diabetes, hypertension and atherosclerosis in the recipient, pulse pressure, initial creatinine and the incidence of delayed graft function (DGF) were higher. After multivariate analysis, the only variables that remained significant for an increased risk of higher RI were recipient age over 55 years, presence of diabetes in the recipient and DGF. Recipient age, previous diabetes mellitus and DGF are the most important determinants of transplant kidney RI in the first days after transplantation. So both the graft recipient and the graft itself, but not the donor, determine intra-renal Doppler indices.

Pathogenesis of tubulointerstitial fibrosis in chronic allograft dysfunction

The term chronic allograft nephropathy (CAN) was originally coined in 1991 to replace chronic rejection which was used too generalized. However, the revised Banff classification, published in 2007, eliminated the term CAN again because it was felt that the term was used too broadly and prevented the search for the underlying cause. Interstitial fibrosis and tubular atrophy are integral parts of chronic allograft dysfunction and represent in the new classification a separate entity with or without the identification of a specific etiology. Myofibroblasts are the key, albeit not exclusive, effector cells in renal fibrogenesis resulting in upregulated extracellular matrix synthesis and eventually in interstitial fibrosis. These cells are formed mainly by stimulation of resident interstitial fibroblasts but also by differentiation processes of periadventitial cells, bone marrow derived cells and by a process entitled epithelial mesenchymal transition (EMT) of tubular epithelial cells. EMT has been described by many groups to be of high prevalence in renal allograft dysfunction contributing to matrix accumulation and renal function deterioration. This is of particular interest because immunosuppressive therapy has differential effects on EMT with calcineurin inhibitors in particular inducing the process. Moreover, specific therapies inhibiting EMT have been applied in experimental studies although the effects of their application in chronic allograft dysfunction remain to be studied. At the same time, immunosuppression may interfere with physiologic clearance of myofibroblasts by apoptosis, explaining in part the high prevalence of interstitial fibrosis in allograft biopsies. The Fas system has been identified to be mainly responsible for this physiologic apoptosis in non-renal scarring models; however, its relevance for renal fibrosis and particular fibrosis in renal allograft dysfunction remains to be determined. These findings point to a cautious and individualized use of immunosuppressive therapy in patients with allografts and particular those with chronic allograft dysfunction not because of rejection processes. Protocols using CNI-free immunosuppression are interesting options to prevent fibrosis in chronic allograft dysfunction.

Induction of chronic renal allograft dysfunction in a rat model with complete and exclusive MHC incompatibility

Chronic allograft dysfunction is one of the most important reasons for late graft loss after renal transplantation. Its etiology is multifactorial and combines immunological as well as non-immunological mechanisms. It is known from large registry data that MHC mismatches are inversely correlated to long term allograft survival. Although this is a well known aspect, the mechanisms of MHC-driven graft damage and the impact of other immunological factors leading to chronic rejection are poorly understood. In patients it is impossible to study MHC mismatches without considering non-MHC differences. Further more common animal models for chronic rejection are all characterized by non-MHC as well as MHC disparities. To exclusively study MHC mediated immunoresponses we established a rat model of renal transplantation using congenic rat strains differing in their entire MHC class I and class II, but sharing the genetic background of the LEW rat. After an initial short term of immunosuppression all animals developed renal impairment with severe albuminuria. Half of the animals died of renal failure in week 7 to 14 and showed pathological characteristics of chronic allograft damage including IF/TA and severe glomerulopathy. The majority of these recipients developed circulating donor-specific MHC alloantibodies. Allografts were significantly infiltrated with T-cells, macrophages and NK-cells. We established a MHC congenic rat model to investigate immunological mechanisms of chronic renal allograft rejection exclusively induced by a complete MHC mismatch. We demonstrated humoral as well as cellular immunoresponses leading to chronic allograft loss in 50% of animals.

Chronic Transplant Vasculopathy Microenvironment Present in the Renal Allograft Reprograms Macrophage Phenotype

Macrophages and monocytes are important in chronic allograft dysfunction. Chronic transplant vasculopathy is an important cause of chronic renal allograft dysfunction. It is characterized by the presence of apoptotic endothelial cells, which generate an apocrine loop that leads to typical myointimal proliferation. However, the exact nature of the reprogramming induced by this microenvironment on recruited monocyte and macrophage phenotypes is ill defined. Human umbilical vein endothelial cells with a serum-starved condition (SSC) for 4 hours were used as a model of apoptotic endothelial cells. This conditioned medium was centrifuged to isolate the apoptotic bodies. Monocytes were harvested from healthy donors using Ficoll gradient and immunomagnetic selection. Blood monocyte–derived macrophages (5–7 days of maturation) were exposed to centrifuged apoptotic cell–conditioned media for 24 hours. Cells were harvested for immunoblotting, and supernates were retained for enzyme-linked immunosorbent assay to determine cytokine and chemokine production. Macrophages generated less IL-6 and IL-8 when cultured in SSC compared with control. Immunoblotting for STAT3 (signal transducer and activator of transcription 3) in macrophages revealed that SSC increased STAT3 levels, which persisted after lipopolysaccharide stimulation. These results suggest that SSC attenuates the pro-inflammatory phenotype in macrophages, through a STAT3-dependent mechanism.

Clinical Implications of Proteinuria in Renal Transplant Recipients Switching to Rapamycin for Chronic Allograft Dysfunction

There is evidence that treatment with m-TOR inhibitors can be beneficial in cases of chronic renal allograft dysfunction. However, some authors have reported poor outcomes of renal function if the switch to m-TOR inhibitors is made in the presence proteinuria > 0.8 g/d. The present study sought to provide a retrospective analysis of the clinical outcome of 63 kidney recipients diagnosed with chronic allograft dysfunction whose therapy was converted to rapamycin including 35 subjects with renal biopsy-proven chronic allograft nephropathy. At the time of conversion, patients were divided into three groups: group I (negative proteinuria), group II (proteinuria between 0.3 and 0.8 g/d), and group III (proteinuria > 0.8 g/d). On conversion, 21 recipients had no proteinuria (group I). After a follow-up of 24.6 +/- 12.8 months, they showed a significant improvement in renal function (previous MDRD4 = 39.9 +/- 11.5 mL/m/1.73 m(2), current MDRD4 50.3 +/- 13.3 mL/m/1.73 m(2), P < .05). Fifteen patients (71.4%) developed proteinuria, which was generally mild (0.8 +/- 0.7 g/d) and controlled with angiotensin-converting enzyme inhibitors (42.8%). In group II (n = 18), renal function clearly stabilized after a follow-up of 23.2 +/- 14.4 months (previous MDRD4 = 30 +/- 8.8 mL/m/1.73 m(2), current MDRD4 = 37 +/- 12.2 mL/m/1.73 m(2), NS), although there was a progressive deterioration of previous proteinuria levels (previous proteinuria 0.4 +/- 0.15 g/d, current proteinuria 1.2 +/- 2 g/d, P < .05), which was more frequent and intense in patients whose treatment with calcineurin inhibitors (CNIs) was suspended (with CNI 0.9 +/- 1.7 g/d, without CNI 1.6 +/- 2.2 g/d, P < .05). Group III (n = 24) had a greater degree of renal insufficiency and a worse outcome after 25.9 +/- 18 months of follow-up, with a frank and progressive deterioration in renal function (previous MDRD4 = 38 +/- 17 mL/m/1.73 m(2), current MDRD4 = 32.5 +/- 19.2 mL/m/1.73 m(2), P < .05) and proteinuria (previous proteinuria = 1.5 +/- 0.7 g/d, current proteinuria = 2.5 +/- 2.2 g/d, P < .05) after conversion. Again, the deterioration in proteinuria was more intense in the patients whose previous CNIs were suspended (with CNI = 1.1 +/- 0.9 g/d, without CNI = 4.2 +/- 2.3 g/d, P < .05). In conclusion, for patients with chronic allograft dysfunction who do not present with proteinuria or whose proteinuria is less than 0.8 mg/d, switching to rapamycin is useful, since it clearly improves or stabilizes renal function, although there may be a discrete increase in proteinuria in the second case. However, among patients with proteinuria greater than 0.8 mg/d accompanied by a greater degree of renal insufficiency, conversion to rapamycin leads to deterioration of proteinuria levels and renal function. These data show that conversion to rapamycin in cases of chronic allograft dysfunction must be made early when there is no proteinuria or it is minimal, and that proteinuria is a predictor of the outcome of allograft function.

Transcriptional Profiles in Urine During Acute Rejection, Bacteriuria, CMV Infection and Stable Graft Function After Renal Transplantation

Acute rejection remains an important cause of renal allograft dysfunction and the need for accurate diagnosis is essential to treat transplant recipients successfully. Molecular markers in urine may serve as a diagnostic tool in acute rejection, but controversy still exists regarding the uniqueness of these biomarkers. We measured mRNA of perforin (PRF), granzyme B (GZMB) and granulysin (GNLY) normalized to cyclophilin B in urine specimens from 24 renal allograft recipients with acute rejection, 12 with bacteriuria, 11 with cytomegalovirus (CMV) infections and 17 controls with stable graft function. Measurements were performed using a real-time polymerase chain reaction assay. mRNA levels (means [95% CI]) for all three markers were significantly higher in recipients with acute rejection compared with controls: PRF (0.23 [0.12-0.42] versus 0.04 [0.02-0.07] P<0.001), GZMB (0.14 [0.09-0.23] versus 0.05 [0.03-0.08] P=0.003), GNLY (0.24 [0.14-0.41] versus 0.06 [0.03-0.11] P=0.001). GZMB and GNLY levels during acute rejection were significantly higher when compared with bacteriuria (P=0.011 and P=0.005 respectively), and PRF level during acute rejection was significantly elevated compared with CMV infection (P=0.015). No significant difference was found when comparing marker levels during bacteriuria and CMV infection to controls. Urinary mRNA levels of PRF, GZMB and GNLY are significantly elevated during acute rejection but not during bacteriuria or CMV infections when compared with recipients with stable graft function. The ability to differentiate acute rejection from bacteriuria and CMV infections was only present for some of the markers, that is why careful consideration should be given before applying this technique to clinical practice.

Dense B cell infiltrates in paediatric renal transplant biopsies are predictive of allograft loss

Recent studies have suggested adverse outcome for renal allograft rejection associated with dense CD20 lymphocytic infiltrates in transplant renal biopsies. We investigated further the relationship between renal allograft survival and CD20+ lymphocytic infiltrates in renal transplant biopsies from children with graft dysfunction. Fifty consecutive unselected renal transplant biopsies were performed for investigation of acute, chronic or acute on chronic renal allograft dysfunction in 48 children aged 1-17 (median 13.1) years, at 0-155 (median 22) months post-transplantation with median follow up of 24 months post-biopsy. Seventeen (35%) graft losses occurred at 1-163 (median 49) months post-transplantation. There was increased graft loss in those with dense (>300 cells/hpf) CD20+ lymphocytic infiltrates present on biopsy (p = 0.043). Dense B-cell infiltrates were also associated with increased glucocorticoid requirement in those with acute cellular rejection (p = 0.0015). There were no significant differences in age, sex, HLA-mismatch, type of transplantation, EBV or CMV serology or baseline immunosuppressive regimens between those with or without dense CD20+ infiltrates. Dense CD20+ lymphocytic infiltrates in renal transplant biopsies are associated with adverse clinical outcome, including increased graft loss. This observation raises the possibility of future studies examining the efficacy of B cell depletion therapy in this clinical context.

Association of Uric Acid With Inflammation, Progressive Renal Allograft Dysfunction and Post-Transplant Cardiovascular Risk

Hyperuricemia is common after kidney transplantation. Although its risk factors are well established, its relation to inflammation, progressive renal dysfunction, and cardiovascular events is unknown. In this study, 405 stable renal transplant recipients with > or = 3 uric acid (UA) and C-reactive protein measurements from January 2005 to April 2008 were identified to determine the relations between UA and C-reactive protein and between UA and the rate of decrease in the estimated glomerular filtration rate (eGFR; using the Modification of Diet in Renal Disease equation) and cardiovascular events. Hyperuricemia was defined as UA >7.1 mg/dl (420 micromol/L) in men and >6.1 mg/dl (360 micromol/L) in women. The prevalence of hyperuricemia was 44% (180 of 405). Hyperuricemia was negatively associated with eGFR (p <0.0001) and positively associated with diuretic use (p = 0.013), time since transplantation (p = 0.014), and triglycerides (p = 0.04). Although UA was correlated with C-reactive protein (p = 0.003), adjustment for eGFR rendered this relation nonsignificant (p = 0.225). The slope of eGFR was +0.144 +/- 0.85 ml/min/1.73 m(2)/month (95% confidence interval 0.032 to 0.257) in those with normal UA levels and -0.091 +/- 0.93 ml/min/1.73 m(2)/month (95% confidence interval -0.235 to +0.054) in patients with hyperuricemia (p = 0.003). There were 17 cardiovascular events in the patients with hyperuricemia and 4 in those with normal UA levels (p = 0.001). In conclusion, hyperuricemia is associated with a decrease in renal allograft function and may be an independent cardiovascular risk factor in transplant recipients. Further studies are needed to establish its role in post-transplantation cardiovascular disease.

BK virus nephropathy in the native kidneys of a pediatric heart transplant recipient

BK virus is a human polyoma virus that may cause nephropathy in immunosuppressed patients. It is a well-recognized cause of renal allograft dysfunction and allograft loss in renal transplant recipients, but it is an infrequent cause of nephropathy outside this setting. There are a few case reports of BK virus nephropathy in the native kidneys of immunosuppressed adult patients with non-renal transplants, but so far it has not been reported in pediatric non-renal solid organ transplant recipients. We report a case of a seven-yr-old heart transplant patient who was diagnosed with BK virus nephropathy, eight months after his second heart transplant. Despite intervention, his renal dysfunction progressed to renal failure. He is currently receiving maintenance hemodialysis and awaiting renal transplantation. It is important to recognize BK virus infection as a possible cause of renal dysfunction in immunosuppressed children who are non-renal transplant recipients.

Diagnostic efficacy of C4d immunostaining in the detection of the humoral component of renal allograft rejection and therapeutic implications

In the current scenario of renal transplantation, the role of immunological methods in the detection of C4d has emerged as a useful adjunct in the recognition of acute humoral rejection (AHR). Few reports of this nature are available from the Indian context although there are several from the Western literature. To study the humoral component of renal allograft rejection in patients presenting clinically with graft dysfunction by histopathological detection of polymorphs in the peritubular capillaries and the expression of C4d using immunological techniques, as well as the response of patients to appropriate antirejection therapy. This study from a tertiary care center reemphasizes the importance of recognition of AHR as a cause of renal allograft dysfunction. Percutaneous renal biopsies were obtained from 40 postrenal transplant patients and evaluated for C4d using immunofluorescence and immunohistochemical methods. SPSS software. Positive expression of C4d was seen in a total of 19/40 cases (44.4%) indicating immunological evidence of AHR. Diffusely positive cases were treated with IV immunoglobulin therapy, plasmapheresis and Rituximab following which graft function was restored. Patients with minimal to focal positive expression of C4d responded well to pulse steroids and change in immunosuppressive therapy. C4d staining is a useful adjunct to routine histopathological methods in evaluating the humoral component of acute renal allograft dysfunction and helps in planning appropriate antirejection therapy with the goal of achieving long-term graft survival.