BKV-associated Nephropathy Research Articles

POS-099 BK POLYOMAVIRUS NEPHROPATHY IN RENAL TRANSPLANT PATIENTS: A RACE WITH TIME?

BK polyomavirus-associated nephropathy (BKVAN) affects up to 15% of renal transplant recipients and is an important cause of graft failure. Higher prevalence of BK virus infection in recent years has been correlated with declining acute rejection rates and the use of potent immunosuppressive agents.

P2.12: Single-Cell Transcriptomic Analysis of Peripheral Blood Reveals the Disparate Subsets of Innate Immune Cells in Kidney Transplant Recipient With BK Virus Infection

Purpose: BK virus (BKV) infection is a common problem in kidney transplant recipients receiving immunosuppressive therapy, resulting in a serious complications including BKV-associated nephropathy and subsequent allograft loss. The purpose of this study was to characterize the disparate blood subsets in BKV infection/nephropathy at the single-cell transcriptional level. Methods: We isolated peripheral blood mononuclear cells from three kidney transplant recipients with stable status, BK viremia and BK nephropathy. Single-cell libraries were generated using the 10x Genomics Chromium Platform. We analyzed multiplexing data in Cell-Ranger Pipeline and used R and “Seurat” packages for downstream analysis. Results: A total of 14,031 cells were analyzed, including 5473 cells from stable patients, 3976 cells from patients with BK viremia, and 4582 cells from patients with BK nephropathy obtained from Illumina HiSeq X. We characterized 17 distinct clusters representing different cell types. Of these, 13 clusters had differentially expressed transcripts for each sample, and the most differentially expressed markers were S100A8, CCR7, LTB, GNLY, GZMK, GZMH, MT-CO1, LINC02446, IGKC, AIF1, HLA-DRA, STMN1. Stable patient had more mRNA upregulated in B cells compared to patients with BK virus infection. In BK viremia, NK cells and monocytes were downregulated, whereas in BK nephropathy, mRNA expression was high in gamma delta T cells. Conclusions: Our study revealed that BK virus infection/nephropathy induce unique characteristics in lymphocytes, which could be confirmed through single-cell RNA analysis. Further studies are needed to characterize the innate immune cells involved in the progression of BK nephropathy.

Antiviral prophylaxis, male sex, and killer immunoglobulin-like receptor KIR2DL3 as markers for stratifying the risk of BK polyomavirus-associated nephropathy in kidney transplant recipients.

The risk of polyomavirus‑associated nephropathy (PyVAN) currently ranges from 1% to 10%, and the risk of graft loss is 10% to 50% within 2 years post‑diagnosis. There is currently no specific antiviral therapy against BK polyomavirus (BKPyV), and no therapeutic approach has been proven superior. Natural killer cells play a key role in the defense against viral infections. A retrospective, single‑center cohort study was performed to investigate the association between the kidney transplant recipients' killer‑cell immunoglobulin‑like receptor (KIR) genotype and PyVAN. We also evaluated other possible risk factors for the occurrence of PyVAN in a population of kidney transplant recipients. DNA samples from 134 kidney transplant recipients were identified for the presence or absence of variable KIR genes and their HLA ligands using polymerase chain reaction with sequence‑specific primers. The analysis revealed that the presence of the inhibitory KIR2DL3 (P = 0.03) was a risk factor for posttransplant PyVAN. We also found that the presence of acute rejection before PyVAN (P = 0.02), male sex (P = 0.04), and the lack of antiviral prophylaxis (P = 0.01) were additional risk factors for posttransplant PyVAN. Our findings confirm that the KIR/HLA genotype plays a significant role in the development of PyVAN and suggest the contribution of both environmental and genetic factors to the incidence of BKPyV infection after kidney transplantation.

Genotypes and Variants of BKPyV in Organ Donors after Brain Death.

Kidney transplantation from a donor with latent BKPyV might be the cause of serious complications, such as BK virus-associated nephropathy. The aim of the study was to determine the prevalence of BKPyV infection in donors after brain death (DBDs), to analyse the molecular variation of BKPyV and to compare clinical and inflammation parameters of DBDs infected with various genotypes of BKPyV. BKPyV was investigated in blood and urine samples of 103 DBDs using PCR followed by sequencing and bioinformatic analysis, and the viral load was assessed by qPCR. Clinical parameters, including cellular markers of inflammation were assessed. The results confirm high prevalence of BKPyV (48%),and genotype IV (49%) over genotype I (43%) and the co-infection with genotypes I and IV in 8.2%. Viral load ranged from 102 to 107 copies/mL, with an average of 1.92 × 106 copies/mL. No specific markers for BKPyV infection were detected among the parameters tested. Infection with genotype I may be associated with the adverse impact on thekidney function, while infection with genotype IV was associated with the anemia Not only the viral load but also the genotype of BKPyV may have an impact on the course of infection.

Levels of donor-derived cell-free DNA and chemokines in BK polyomavirus-associated nephropathy.

BK polyomavirus-associated nephropathy (BKPyVAN) carries a risk of irreversible allograft injury. While detection of BK viremia and biopsy assessment are the current diagnostic gold standard, the diagnostic value of biomarkers reflecting tissue injury (donor-derived cell-free DNA [dd-cfDNA]) or immune activation (C-X-C motif chemokine ligand [CXCL]9 and CXCL10) remains poorly defined. For this retrospective study, 19 cases ofBKPyVANwere selected from the Vienna transplant cohort (biopsies performed between 2012 and 2019). Eight patients with T cell-mediated rejection (TCMR), 17 with antibody-mediated rejection (ABMR) and 10 patients without polyomavirus nephropathy or rejection served as controls. Fractions of dd-cfDNAwere quantified using next-generation sequencing and CXCL9 and CXCL10 were detected using multiplex immunoassays. BKPyVANwas associated with a slight increase in dd-cfDNA(median; interquartile range: .38% [.27%-1.2%] vs. .21% [.12%-.34%] in non-rejecting control patients; p=.005). Levels were far lower than in ABMR (1.2% [.82%-2.5%]; p=.004]), but not different from TCMR (.54% [.26%-3.56%]; p=.52). Within theBKPyVANcohort, we found no relationship between dd-cfDNAlevels and the extent of tubulo-interstitial infiltrates,BKPyVANclass and BK viremia/viruria, respectively. In some contrast to dd-cfDNA, concentrations of urinary CXCL9 and CXCL10 exceeded those detected in ABMR, but similar increases were also found in TCMR. BKPyVANcan induce moderate increases in dd-cfDNAand concomitant high urinary excretion of chemokines, but this pattern may be indistinguishable from that of TCMR. Our results argue against a significant value of these biomarkers to reliably distinguishBKPyVANfrom rejection.

Identifying RBBP7 as a Promising Diagnostic Biomarker for BK Virus-Associated Nephropathy

BK virus-associated nephropathy (BKVN) remains a major infectious complication due to powerful immunosuppression in kidney transplant recipients, and its histologic appearance can mimic rejection, leading to diagnostic and treatment dilemmas thus molecular diagnostic methods would be beneficial. We collected gene expression profiles of 169 kidney biopsies taken from BKVN, rejection, and stable functioning allografts, based on single sample gene set enrichment analysis and random forest algorithm, and three hallmark activities associated with DNA damage and proliferation were found to be relatively specific in BKVN. Subsequently, weighted gene co-expression network analysis and support vector machines (SVM) algorithm identified RBBP7 as a robust and promising biomarker with high accuracy in both training and validation cohorts (AUC =0.938, 0.977, respectively). Besides, potential drugs for BKVN treatment such as mepacrine were discovered, which may contribute to targeted antiviral therapy and effective patient management rather than simply reducing the doses of immunosuppressive agents in clinical practice. RBBP7 (retinoblastoma binding protein 7) serves as component of serval complexes that regulate chromatin metabolism and functions in affecting DNA replication and controlling cell proliferation. In this research, upregulation of RBBP7 was found to be associated with the higher infiltration of CD8 naïve T, iTreg, and neutrophil cells and the lower amounts of Th1, central memory T, NKT, CD8 T, and dendritic cells. Moreover, the infiltration of Th1, Th17, and NKT cells was steadily different between BKVN and rejection allografts through immune cell assessment. In conclusion, we identified and verified RBBP7 as a molecular biomarker for BKVN diagnosis, which demonstrated great distinguishing ability with allograft rejection and would support clinical decision-making.

Pretransplantation seroreactivity in kidney donors and recipients as a predictive factor for posttransplant BKPyV-DNAemia.

BK polyomavirus (BKPyV) often reactivates after kidney transplantation, causing BKPyV-associated nephropathy (BKPyVAN) in 1%–10% of cases with a potential detrimental effect on allograft survival. Kidney transplant recipients are regularly screened for BKPyV DNA in plasma. As this strategy may not always reduce the risk of BKPyVAN, other predictive markers are needed. To evaluate the role of pretransplant BKPyV-specific antibody, 210 kidney transplant recipients and 130 donors were screened for BKPyV DNA and BKPyV-specific antibodies. We found that the donor BKPyV immunoglobulin G (IgG) seroprevalence and antibody level were strongly associated with BKPyV-DNAemia and BKPyVAN, although multivariant analysis found the presence of anti-BKPyV-specific antibodies as a predictive factor only for BKPyV-DNAemia. The pretransplant recipient status had no effect on posttransplant BKPyV-DNAemia and BKVAN. BKPyV IgG levels remained stable in BKPyV-negative recipients during 1-year follow-up, while a considerable increase was observed in BKPyV-positive patients. The presence of anti-BKPyV-specific antibodies in kidney allograft donors is a good and reliable predictive marker for posttransplant BKPyV replication with relevance to risk stratification in transplant recipients.

BK Virus Infection and BK-Virus-Associated Nephropathy in Renal Transplant Recipients.

Poliomavirus BK virus (BKV) is highly infective, causing asymptomatic infections during childhood. After the initial infection, a stable state of latent infection is recognized in kidney tubular cells and the uroepithelium with negligible clinical consequences. BKV is an important risk factor for BKV-associated diseases, and, in particular, for BKV-associated nephropathy (BKVN) in renal transplanted recipients (RTRs). BKVN affects up to 10% of renal transplanted recipients, and results in graft loss in up to 50% of those affected. Unfortunately, treatments for BK virus infection are restricted, and there is no efficient prophylaxis. In addition, consequent immunosuppressive therapy reduction contributes to immune rejection. Increasing surveillance and early diagnosis based upon easy and rapid analyses are resulting in more beneficial outcomes. In this report, the current status and perspectives in the diagnosis and treatment of BKV in RTRs are reviewed.

BK polyomavirus-associated nephropathy

BK polyomavirus (BKPyV) is a ubiquitous virus residing in the kidney tubules and is clinically significant only in immunocompromised patients. In clinical practice, BKPyV is a causative pathogen of BKPyV associated nephropathy (BKVAN) in kidney allograft recipients or hemorrhagic cystitis of hematopoietic stem cell transplant recipients. Currently, there is no effective treatment for BKVAN; therefore, careful monitoring and prudent modification of immunosuppression are necessary to prevent BKVAN. In this article, the epidemiology, pathophysiology, and current management strategies for BKVAN are reviewed.

Using Both Plasma and Urine Donor-Derived Cell-Free DNA to Identify Various Renal Allograft Injuries.

This study was designed to investigate the association between donor-derived cell-free DNA (dd-cfDNA) and renal allograft injuries. This single-center study enrolled 113 adult kidney transplant recipients with kidney biopsies. Plasma and urine dd-cfDNA was detected by target region capture sequencing. Plasma dd-cfDNA fraction was increased in multiple types of injuries, but most significantly in antibody-mediated rejection. Plasma dd-cfDNA fraction in isolated antibody-mediated rejection (1.94%, IQR: 1.15%, 2.33%) was higher than in T cell-mediated rejection (0.55%, IQR: 0.50%, 0.73%, P = 0.002) and negative biopsies (0.58%, IQR: 0.42%, 0.78%, P < 0.001), but lower than in mixed rejection (2.49%, IQR: 1.16%, 4.90%, P = 0.342). Increased urine dd-cfDNA concentration was associated with several types of injury, but most significantly with BK polyomavirus-associated nephropathy. Urine dd-cfDNA concentration in BK polyomavirus-associated nephropathy (12.22 ng/mL, IQR: 6.53 ng/mL, 31.66 ng/mL) was respectively higher than that in T cell-mediated rejection (5.24 ng/mL, IQR: 3.22 ng/mL, 6.99 ng/mL, P = 0.001), borderline change (3.93 ng/mL, IQR: 2.45 ng/mL, 6.30 ng/mL, P < 0.001), and negative biopsies (3.09 ng/mL, IQR: 1.94 ng/mL, 5.05 ng/mL, P < 0.001). Plasma dd-cfDNA fraction was positively associated with glomerulitis (r = 0.365, P < 0.001) and peri-tubular capillaritis (r = 0.344, P < 0.001), while urine dd-cfDNA concentration correlated with tubulitis (r = 0.302, P = 0.002). Both plasma and urine dd-cfDNA are sensitive markers for renal allograft injuries. The interpretation of a specific disease by dd-cfDNA should be combined with other clinical indicators.

High-Frequency US for BK Polyomavirus-associated Nephropathy after Kidney Transplant.

Background BK polyomavirus-associated nephropathy (BKPyVAN) is an important cause of chronic renal allograft dysfunction. However, US features indicative of BKPyVAN have not been fully evaluated. Purpose To assess the value of high-frequency US for the diagnosis of BKPyVAN in kidney transplant recipients. Materials and Methods In this prospective cohort study, participants who tested positive for BK viruria after kidney transplant from September 2019 to January 2021 were evaluated with high-frequency US 1 day before biopsy. Clinical characteristics and US features were compared between participants with and without BKPyVAN. Significant predictors associated with BKPyVAN were determined using logistic regression analyses. The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic performance. Results A total of 105 participants who underwent kidney transplant (mean age, 38 years ± 11 [SD]; 63 men) were evaluated; 45 participants were diagnosed with BKPyVAN. Multivariable analysis demonstrated that eccentric hydronephrosis and subcapsular hypoechoic areas were independent factors for BKPyVAN. The AUC for predicting BKPyVAN according to subcapsular hypoechoic areas was 0.66 (95% CI: 0.55, 0.77), with a specificity of 92% (55 of 60 participants). The AUC of combined US (eccentric hydronephrosis plus subcapsular hypoechoic area) and clinical (urine BKPyV DNA load [BKPyV-DNA] plus BK viremia) features was 0.90, with a specificity of 92% (55 of 60 participants). Parenchymal hyperechoic and subcapsular hypoechoic areas were independent factors for differentiating BKPyVAN from transplant rejection. The pooled specificity of subcapsular hypoechoic areas was 96% (21 of 22 participants), with an AUC of 0.67 (95% CI: 0.54, 0.80). For the combination of US (parenchymal echogenicity plus subcapsular hypoechoic area) and clinical (urine BKPyV-DNA plus time since transplant) features, the AUC reached 0.92 and specificity was 82% (18 of 22 participants). Conclusion High-frequency US characteristics are valuable for diagnosing BK polyomavirus-associated nephropathy (BKPyVAN) and distinguishing BKPyVAN from rejection in kidney transplant recipients. © RSNA, 2022 Online supplemental material is available for this article.

MO1008: The Role of IL-27/IL-27R in BKPYV Reactivation and Graft Rejection in Kidney Transplant Recipients

Abstract BACKGROUND AND AIMS Kidney transplantation is the only cure for patients with end-stage renal disorders. Therefore, protecting these patients from transplant rejection is a critical lifesaving project after transplantation. Graft rejection and BK polyoma virus (BKPyV) associated nephropathy (BKVAN) is one of the common causes of graft loss among kidney transplant recipients (KTRs) through activating innate and adaptive immunity. In between, the role of cytokines is very perilous in handling the immune responses against rejection, such as IL-27, and in this study, it is tried to investigate the role of IL-27 and its receptor (IL-27R; WSX-1) in KTRs. METHOD EDTA-treated blood samples were collected from 90 KTRs that were divided into three equal groups of BKV-inactive/non-reject (G1), BKV-active/non-reject (G2) and BKV-inactive/reject (G3), after being monitored by real-time PCR (Taq-Man) in plasma. A total of 30 normal individuals were considered as healthy control group (G0). A real-time PCR (SYBR Green) technique is used to determine the expression level of studied genes. RESULTS The results of gene expression comparisons showed that the expression level of IL-27 was significantly higher in G1 compared with the G2 group. Analysis also showed that the difference in the expression level of genes between the G3 and G0 groups was statistically significant. Also, the same comparison between the G1 and G0 groups showed a significant difference. The area under the ROC curve (AUC) showed that IL-27 is a significant discriminating molecule between all three studied groups of patients. The analyses revealed that the expression level of studied genes has a significant correlation with viral load. Finally, the ROC analysis showed that IL-27 and IL-27R seem to be important molecules for discrimination between G2 and G3 patient groups. CONCLUSION It is not easy to determine the IL-27 pro-inflammatory function as an endogenous regulatory mechanism, which might be one of the reasons for the immune system’s inability to inhibit the BKPyV reactivation in KTRs. Therefore, knowing the fact that in vivo loss of IL-27 signalling would not make drastic defects in immune development, turns IL-27 an attractive candidate for therapeutic research. It is important to consider the role of cytokines in different rejection conditions and the role of some cytokines should be more studied, such as IL-27 and IL-27R in course of kidney rejections, which happens especially between 2 weeks and 2 months after transplantation.

Genomic Mutations of BK Polyomavirus in Patients after Kidney Transplantation: A Cross-Sectional Study in Vietnam

Objectives: The purpose of this study was to identify the SNP sites and determine the BKV genotype circulating in kidney-transplant Vietnamese recipients based on the VP1 gene region. Methods: 344 samples were collected from post-kidney-transplant recipients at the 103 Vietnam Military Hospital to investigate the number of BKV infections. Positive samples with a sufficient virus concentration were analyzed by nested PCR in the VP1 region, sequencing detected genotyping and single-nucleotide polymorphism. Results: BKV infection was determined in 214 patients (62.2%), of whom 11 (5.1%) were diagnosed with BKV-associated nephropathy. Among the 90 BKV-I strains sequenced, 89 (98.88%) were strains of I/b-1 and 1 (1.12%) was strain I/b-2. The 60 BKV-IV strains had a greater diversity of subgroups, including 40% IV/a-1, 1.66% IV/a-2, 56.68% IV/c-1, and 1.16% IV/c-2. Additionally, of 11 cases diagnosed with BKVN, seven belonged to subgroup I/b-1 (63.6%) and four to subgroup IV/c-1 (36.4%). Moreover, 22 specific SNPs that were genotype I or IV were determined in this Vietnamese population. Specifically, at position 1745, for the Vietnamese BKV-IV strains, the SNP position (A→G) appeared in 57/60 samples (95%). This causes transformation of the amino acid N→S. This SNP site can enable detection of genotype IV in Vietnam. It represents a unique evolution pattern and mutation that has not been found in other international strains. Conclusion: The BKV-I genotype was more common than BKV-IV; however, mutations that occur on the VP1 typing region of BKV-IV strains were more frequent than in BKV-I strains.

Endoplasmic Reticulum Stress Mediates Renal Tubular Vacuolation in BK Polyomavirus-Associated Nephropathy.

ObjectiveThis study aimed to explore the molecular mechanism of cytoplasmic vacuolation caused by BK polyomavirus (BKPyV) and thus search for potential target for drug repurposing.MethodsMorphological features of BK polyomavirus-associated nephropathy (BKPyVAN) were studied under light and electron microscopes. Microarray datasets GSE75693, GSE47199, and GSE72925 were integrated by ComBat, and differentially expressed genes (DEGs) were analyzed using limma. Furthermore, the endoplasmic reticulum (ER)-related genes obtained from GenCLiP 2.0 were intersected with DEGs. GO and KEGG enrichment pathways were performed with intersection genes by R package clusterProfiler. The single-cell RNA sequencing (scRNA-seq) from a BKPyVAN recipient was analyzed with a dataset (GSE140989) downloaded from Gene Expression Omnibus (GEO) as control for gene set variation analysis (GSVA). Immunohistochemistry and electron microscopy of kidney sections from drug-induced ERS mouse models were performed to explore the association of ERS and renal tubular vacuolation. Protein–protein interaction (PPI) network of the intersection genes was constructed to identify hub target. AutoDock was used to screen Food and Drug Administration (FDA)-approved drugs that potentially targeted hub gene.ResultsLight and electron microscopes exhibited obvious intranuclear inclusions, vacuoles, and virus particles in BKPyV-infected renal tubular cells. Transcriptome analysis revealed 629 DEGs between samples of BKPyVAN and stable transplanted kidneys, of which 16 were ER-associated genes. GO analysis with the intersection genes illustrated that ERS-related pathways were significantly involved, and KEGG analysis showed a prominent enrichment of MAPK, Toll-like receptor, and chemokine signaling pathways. GSVA analysis of the proximal tubule revealed similar pathways enrichment. An electron microscope image of the kidney from ERS mouse models showed an obvious renal tubular vacuolation with prominent activation of ERS markers verified by immunohistochemistry. Furthermore, DDIT3 was identified as the hub gene based on PPI analysis, and ZINCOOOOO1531009 (Risedronate) was indicated to be a potential drug for DDIT3.ConclusionERS was involved in renal tubular cytoplasmic vacuolation in BKPyVAN recipients. Risedronate was screened as a potential drug for BKPyVAN by targeting DDIT3.

BK Virus Nephropathy in HIV-Positive Heart-Kidney Transplant Recipient

<h3>Introduction</h3> BK viral reactivation is common in immunosuppressed states such as advanced HIV and organ transplantation. An important cause of kidney transplant allograft dysfunction and loss is BK reactivation leading to BK virus-associated nephropathy (BKVAN). We describe a problematic case of BKVAN in a combined heart-kidney transplant (HKT) recipient with well controlled HIV. <h3>Case Report</h3> A 46-year-old man with HIV (CD4 726 cells/mm³, HIV viral load <20 copies/mL) on dolutegravir/rilpivirine, non-ischemic cardiomyopathy, and HIV nephropathy underwent HKT with basiliximab induction and maintenance tacrolimus (goal 5-8 ng/mL), mycophenolate mofetil (MMF), and prednisone. Immediate post-transplant course was complicated by delayed renal graft function with acute tubular necrosis and urine leak. HIV has remained well controlled. Post-transplant nadir CD4 count was 639 cells/mm³. The patient developed BK viuria (90,891,555 copies/mL) and BK viremia (4,500 copies/mL) on post-transplant day (PTD) 55 and 62, respectively. Although MMF dose was reduced from 1,000 mg to 500 mg daily, renal allograft biopsy shortly after showed Class B1 BKVAN with no evidence of rejection. Patient began bi-weekly 5 mg/kg cidofovir infusions. Prednisone was decreased from 10 mg to 5 mg daily. Mycophenolate was further reduced to 250 mg daily and steroids were discontinued due to persistently high BK viral load. However, after decline in ejection fraction (EF) to 50% and suspicion for cardiac graft rejection, MMF dose was increased back to 500 mg daily. Endomyocardial biopsies have shown no evidence of rejection with negative donor specific anti-HLA antibodies. Renal function declined with serum creatinine (SCr) peaking at 2.28 mg/dL. Patient has remained on cidofovir infusions and reduced immunosuppression, on which SCr has stabilized to 1.8 mg/dL on PTD 694. Cardiac allograft function remains normal with an EF of 71% on PTD 644. BK viral load peaked at 16,672,298 copies/mL and remains elevated at 4,821 copies/mL on PTD 702. <h3>Summary</h3> We present a case of BKVAN in a HIV+ HKT recipient. This case demonstrates the difficulty of BKVAN management in dual organ transplant since heart allograft management requires higher levels of maintenance immunosuppression. It is unclear if HIV contributed to development of BKVAN in this recipient. Better antiviral therapies are needed for control of BK virus infections after transplant.

Outcomes of Everolimus Plus Standard-Dose Tacrolimus Immunosuppression in De Novo Kidney Transplant: A Retrospective, Single-Center Study of 225 Transplants.

In this study, our aim was to compare the outcomes of everolimus versus mycophenolate mofetil plus standard-dose tacrolimus immunosuppression in patients who received de novo kidney transplant at our center in Fukuoka, Japan. In this retrospective, observational, single-center, inverse probability of treatment weighting analysis study, 225 recipients who underwent kidney transplant at our center between January 2013 and December 2018 were included. The variables considered were recipient age/sex, duration of dialysis, cytomegalovirus mismatch (seronegative recipient and seropositive donor), cause of end-stage renal disease, donor age/sex, and number of HLA mismatches. Our analyses included 85 transplant recipients in the everolimus group and 141 transplant recipients in the mycophenolate mofetil group (n = 226 overall). There were no significant differences between the groups at 1 year for incidence of patient death and allograft loss, biopsy-proven acute rejection, BK virus-associated nephropathy, surgical complications, delayed graft function, and posttransplant diabetes mellitus. Incidence of cytomegalovirus infection and estimated glomerular filtration rate were significantly lower in the everolimus group than in the mycophenolate mofetil group. Posttransplant triglyceride and low-density lipoprotein were higher in the everolimus group than in the mycophenolate mofetil group. Multivariate ordered logistic analysis showed that older donor age and an acute rejection episode, but not induction with everolimus or mean tacrolimus trough concentration throughoutthe firstpostoperative year,were significant risk factors for severity of interstitial fibrosis/tubular atrophy at the 1-year protocol biopsy (P = .004 and P < .001,respectively). Short-term outcomes with everolimus plus standard-dose tacrolimus in recipients of de novo kidney transplant were comparable to those with mycophenolate mofetil plus standard-dose tacrolimus.

Personalized immunosuppression after kidney transplantation.

With advances in immunosuppressive therapy, there have been significant improvements in acute rejection rates and short-term allograft survival in kidney transplant recipients. However, this success has not been translated into long-term benefits by the same magnitude. Optimization of immunosuppression is important to improve the clinical outcome of transplant recipients. It is important to note that each patient has unique attributes and immunosuppression management should not be a one-size-fits-all approach. Elderly transplant patients are less likely to develop acute rejection but more likely to die from infectious and cardiovascular causes than younger patients. For those with post-transplant cancers and BK polyomavirus-associated nephropathy, reduction of immunosuppression can increase the risk of rejection. Therapeutic drug monitoring (TDM) is routinely used for dosage adjustment of several immunosuppressive drugs. It has been hoped that pharmacogenetics can be used to complement TDM in optimizing drug exposure. Among the various drug-genotype pairs being investigated, tacrolimus and CYP3A5 gives the most promising results. Different studies have consistently shown that CYP3A5 expressers require a higher tacrolimus dose and take longer time to achieve target blood tacrolimus levels than nonexpressers. However, for pharmacogenetics to be widely used clinically, further trials are necessary to demonstrate the clinical benefits of genotype-guided dosing such as reduction of rejection and drug-related toxicities. The development of different biomarkers in recent years may help to achieve true personalized therapy in transplant patients.

Viral-specific cytotoxic T-cell responses in HLA-sensitized kidney transplant patients maintained on everolimus and low-dose tacrolimus.

Maintenance with "everolimus + reduced dose tacrolimus" (Ev + Taclow ) was reported to reduce the risk of viral infections compared to "tacrolimus + mycophenolate mofetil" (Tac + MMF). Here we examined viremia and viral-specific T-cell (viral-Tc) responses in patients treated with Ev + Taclow versus Tac + MMF in highly-human leukocyte antigen (HLA)-sensitized patients. HLA-sensitized (HS) kidney transplant patients were monitored pre- and post-transplant for viremia (cytomegalovirus (CMV), BK, and Epstein-Barr virus (EBV)) by polymerase chain reaction (PCR) in 19 Ev + Taclow and 48 Tac + MMF patients. For CMV PCR analysis, we compared infection rates in 19 Ev + Taclow patients to 48 CMV D+/R- (#28) or CMV D-/R- (#20) Tac + MMF patients. CMV-specific cytotoxic T cell (CMV-Tc) and EBV-specific cytotoxic T cell (EBV-Tc) were evaluated by cytokine flow cytometry, and donor-specific antibody (DSA) levels by Luminex for selected patients in both groups. CMV and EBV viremia rates were similar in Ev + Taclow versus Tac + MMF patients, but BK virus (BKV) rates were significantly higher in Ev + Taclow patients. No patient in either group developed BK virus-associated allograft nephropathy (BKAN) or post-transplant lymphoproliferative disorders (PTLD). CMV-Tc and EBV-Tc decreased significantly after alemtuzumab induction but returned to pre-treatment levels 1-2 months post-transplant in most patients. de novo DSA was similar in both groups as were patient and graft survival and graft rejection. CMV-Tc and EBV-Tc were similar in Ev + Taclow and Tac + MMF patients. EBV and CMV viremia rates were similar over 1 year. BKV rates were significantly higher in Ev + Taclow patients suggesting no benefit for Ev + Taclow in enhancing viral-Tc effector functions or limiting viral infections.

A Nomogram for Predicting BK Virus Activation in Kidney Transplantation Recipients Using Clinical Risk Factors.

BK virus is a common opportunistic viral infection that could cause BK virus-associated nephropathy in renal transplant recipients. Thus, we retrospectively analyzed clinical and laboratory data associated with a higher risk of BK virus activation from 195 renal transplant recipients by the multivariate logistic regression analysis and performed the external validation. Results showed that patients with BK virus active infection were associated with a deceased donor, had lower direct bilirubin levels, a higher proportion of albumin in serum protein electrophoresis, and lower red blood cells and neutrophil counts. The multivariate logistic regression analyses revealed that the living donor, direct bilirubin, and neutrophil counts were significantly associated with BK virus activation. The logistic regression model displayed a modest discriminability with the area under the receiver operating characteristic curve of 0.689 (95% CI: 0.607–0.771; P < 0.01) and also demonstrated a good performance in the external validation dataset (the area under the receiver operating characteristic curve was 0.699, 95% CI: 0.5899–0.8081). The novel predictive nomogram achieved a good prediction of BK virus activation in kidney transplant recipients.

Multiplex Immunofluorescence Assay of Infiltrating Mononu-Clear Cell Subsets in Acute T-Cell-Mediated Rejection and BK Virus-Associated Nephropathy in the Allograft Kidney.

Renal allograft biopsy is the gold standard procedure for diagnosis of kidney rejection via specific pathological changes. To provide a better assessment of immunologic events in acute T-cell-mediated rejection (acute TCMR) and BK virus-associated nephropathy (BKVAN) cases, we used multiplex immunofluorescence staining to identify infiltrating mononuclear cell subsets in the cortex area of transplanted kidneys. Antibodies to CD4, CD8, CD20, CD68, Foxp3, and cytokeratin were used. In cortical interstitium, CD8+ cells were significantly more prevalent in acute TCMR than BKVAN cases (34% vs. 22.8%, p = 0.034). In medulla, CD20+ cells were significantly more prevalent in BKVAN than acute TCMR cases (51.9% vs. 11.3%, p = 0.028).