A delicate balance between rejection and BK polyomavirus associated nephropathy; A retrospective cohort study in renal transplant recipients

Incidence and Outcomes of BK Virus Nephropathy in Kidney Transplant Recipients With Steroid-Free Maintenance Immunosuppression

BACKGROUND

BK virus nephropathy (BKVN) is a significant complication in kidney transplant recipients, resulting in graft dysfunction and potentially leading to graft loss. This study aims to investigate the incidence and outcomes of BKVN in kidney transplant recipients receiving steroid-free maintenance immunosuppression in a Latin -American cohort.

METHODS

Case series study of BKVN among kidney transplant recipients who underwent transplantation between 2008 and 2023. The primary outcome was graft loss caused by BKVN, excluding death with function. Secondary outcomes included graft function and acute rejection episodes. The statistical analysis involved descriptive statistics and the Kaplan-Meier (K-M) method to plot the overall probabilities of not initiating dialysis.

RESULTS

During the 15-year period, 2236 kidney transplants were performed, BKVN was histologically diagnosed in 38 kidney recipients and 33 cases were analyzed. Median age was 50 years and men were 48.5% of patients. A total of 45.4% of BKVN occurred within the first 12 months of transplant. The incidence of BKVN was 1.6% but it varied by era. The rate of graft loss was 75.7% (25 cases). The K-M graft survival probability at 6 months and 12 months after diagnosis of BKVN was 38.3% (95% CI 24.7-59.4) and 22.3% (95% CI 11.7-42.8), respectively.

CONCLUSION

BKVN affected 1.6% of transplant recipients and it was associated with high-rate of graft loss. We observed that significant graft disfunction at the time of diagnosis resulted in worse outcomes with a reduced probability of graft survival.

Economic Evaluation of Screening for Polyomavirus Infection in Kidney Transplant Recipients: A Cost-Utility Analysis

Screening for polyomavirus infection after kidney transplantation is recommended by clinical practice guidelines, but cost-effectiveness of this strategy is uncertain. The aim of this study was to estimate the incremental costs and benefits of routine screening for polyomavirus infection compared with no screening in kidney transplant recipients.

Chronic Kidney Allograft Disease: New Concepts and Opportunities

Chronic kidney disease (CKD) is increasing in most countries and kidney transplantation is the best option for those patients requiring renal replacement therapy. Therefore, there is a significant number of patients living with a functioning kidney allograft. However, progressive kidney allograft functional deterioration remains unchanged despite of major advances in the field. After the first post-transplant year, it has been estimated that this chronic allograft damage may cause a 5% graft loss per year. Most studies focused on mechanisms of kidney graft damage, especially on ischemia-reperfusion injury, alloimmunity, nephrotoxicity, infection and disease recurrence. Thus, therapeutic interventions focus on those modifiable factors associated with chronic kidney allograft disease (CKaD). There are strategies to reduce ischemia-reperfusion injury, to improve the immunologic risk stratification and monitoring, to reduce calcineurin-inhibitor exposure and to identify recurrence of primary renal disease early. On the other hand, control of risk factors for chronic disease progression are particularly relevant as kidney transplantation is inherently associated with renal mass reduction. However, despite progress in pathophysiology and interventions, clinical advances in terms of long-term kidney allograft survival have been subtle. New approaches are needed and probably a holistic view can help. Chronic kidney allograft deterioration is probably the consequence of damage from various etiologies but can be attenuated by kidney repair mechanisms. Thus, besides immunological and other mechanisms of damage, the intrinsic repair kidney graft capacity should be considered to generate new hypothesis and potential therapeutic targets. In this review, the critical risk factors that define CKaD will be discussed but also how the renal mechanisms of regeneration could contribute to a change chronic kidney allograft disease paradigm.

Intravenous immunoglobulins do not prove beneficial to reduce alloimmunity among kidney transplant recipients with BKV-associated nephropathy

Reduced immunosuppression during BKV-DNAemia has been associated with T-cell mediated rejection (TCMR), de novo donor-specific antibodies (DSA) and antibody-mediated rejection (ABMR). Intravenous immunoglobulins (IVIG) may reduce alloimmunity. We studied 860 kidney transplant recipients (KTRs) for the development of BKV-DNAuria and BKV-DNAemia (low-level <10 000 IE/ml, high-level >10 000 IE/ml). 52/131 KTRs with high-level BKV-DNAemia received IVIG. The HLA-related immunological risk was stratified by the Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) algorithm. BKV-DNAuria only was observed in 86 KTRs (10.0%), low-level BKV-DNAemia in 180 KTRs (20.9%) and high-level BKV-DNAemia in 131 KTRs (15.2%). KTRs with low-level BKV-DNAemia showed significantly less TCMR compared to KTRs with high-level BKV-DNAemia (5.2% vs. 25.5%; P < 0.001) and no BKV-replication (13.2%; P = 0.014), lowest rates of de novo DSA (21.3%), ABMR (9.2%) and flattest glomerular filtration rate (GFR) slope (-0.8 ml/min). KTRs with low-level BKV-DNAemia showed significantly higher median (interquartile range) total PIRCHE if they developed TCMR [100.22 (72.6) vs. 69.52 (49.97); P = 0.020] or ABMR [128.86 (52.99) vs. 69.52 (49.96); P = 0.005]. Administration of IVIG did not shorten duration of BKV-DNAemia (P = 0.798) or reduce TCMR, de novo DSA and ABMR (P > 0.05). KTRs with low-level BKV-DNAemia showed best protection against alloimmunity, with a high number of PIRCHE co-determining the remaining risk. The administration of IVIG, however, was not beneficial in reducing alloimmunity.

Risk factors for progression from low level BK dnaemia to unfavorable outcomes after BK management via immunosuppressive reduction

BACKGROUNDS

Effective management of BK viremia (BKPyV-DNAemia) in kidney transplant recipients (KTRs) involves regular monitoring and adjustment of immunosuppression. With this strategy, the majority of patients will clear BK or have ongoing, but non-significant, low-level BKPyV-DNAemia. However, despite adjustments, some will develop more severe sequelae of BK including BKPyV-DNAemia >5 log10 copies/mL and BK nephropathy, and others may develop de novo DSA (dnDSA) or acute rejection (AR).

METHODS

This was a single-center study of KTRs transplanted at the University of Wisconsin-Madison between 01/01/2015 and 12/31/2017. In this study, we sought to elucidate characteristics associated with the progression of BKPyV-DNAemia to unfavorable outcomes after decreasing immunosuppressive medications for the management of BK viremia as described in consensus guidelines.

RESULTS

A total of 224 KTRs fulfilled our selection criteria; 118 (53%) resolved or had persistent low DNAemia, 64 (28%) had severe BK/nephropathy, and 42 (19%) developed dnDSA or AR. In multivariable analysis, female gender (HR: 2.05; 95% CI: 1.08-3.90; P = .02); previous rejection (HR: 2.90; 95% CI: 1.04-8.12; P = .04), and early infection (HR: 0.81; 95% CI: 0.72-0.90; P < .001) were associated with the development of severe BK/nephropathy. Conversely, non-depleting induction at transplant (HR: 2.06; 95% CI: 1.03-4.11; P = .03), HLA mismatches >3 (HR: 2.27; HR: 1.01-5.06; P = .04), and delayed graft function (HR: 4.14; 95% CI: 1.12-15.28; P = .03) were associated with development of dnDSA and/or rejection.

CONCLUSION

Our study suggests that almost half of KTRs with BKPyV-DNAemia managed by our immunosuppressant adjustment protocol progress unfavorably. Identification of these risk factors could assist the frontline clinician in creating an individualized immunosuppressive modification plan potentially mitigating negative outcomes.

Total nephroureterocystectomy and urethrectomy due to urothelial carcinoma associated with the BK polyomavirus infection after kidney transplantation: a case report with literature review

Background

BK polyomavirus (BKPyV) infection after kidney transplantation is an important cause of graft failure among kidney transplant recipient and may cause malignant tumor, although the association between BKPyV infection and malignant tumor has been controversial yet.

Case presentation

We report a case of a 39-year-old-male kidney transplantation (KTx) recipient with urine BKPyV replication who developed a graft pelvic tumor with the positive Simian virus 40 large T antigen (SV40 TAg). The patients received a living-related KTx from his 65-year-old mother. A protocol biopsy at 14 months after KTx showed BKPyV-associated nephropathy. Therefore, the dose of immunosuppressants was reduced, resulting in improved BKPyV viremia, but viruria persisted. About 117 months after KTx, urine cytology showed atypical cells suspicious for malignancy. Cystoscopy revealed a tumor on the neck of the bladder. Transurethral resection of the bladder tumor (TUR-BT) was performed; however, the diagnosis of malignancy was not confirmed at that time. Six months after the TUR-BT, urine cytology showed atypical cells definite for malignancy. Computed tomography and retrograde pyelography showed no evidence of urinary tract tumor and metastasis. Subsequently, total nephroureterocystectomy and urethrectomy were performed. Histological examination of the graft ureter revealed a high-grade urothelial carcinoma, with glandular differentiation, pT1. Immunohistochemically, the tumor showed positivities for SV40 TAg and p53, along with increased Ki67 labeling cells were increased. By contrast, nonneoplastic cells were negative for SV40 TAg. At the time of writing the present manuscript, the patient is free from recurrence or residual tumor and being closely monitored without additional therapy, 32 months after the surgery.

Conclusion

The relationship between BKPyV infection after KTx and bladder carcinogenesis remains to be elucidated. However, when the KTx recipients who continue to have BKPyV infection for a long time are treated, the possibility of risk factors for renourinary carcinoma should always be carefully considered.

Renal Allograft Biopsies with Polyomavirus BK Nephropathy: Turin Transplant Center, 2015-19

Background: In kidney transplant patients, polyomavirus-associated nephropathy (PVAN) represents a serious complication; the key factor for the development of PVAN is immunosuppression level and modulation of anti-rejection treatment represents the first line of intervention. Allograft biopsy and histology remain the criterion standard for diagnosing PVAN. Methods: All consecutive renal biopsies with the diagnosis of PVAN carried out at the University Hospital City of Health and Science of Turin over a five-years period were studied. Renal allograft biopsy was performed due to renal function alterations associated to medium-high polyomavirus BK (BKV)-DNA levels on plasma specimen. Results: A total of 21 patients underwent a first biopsy to diagnose a possible BKV nephropathy, in 18, a second biopsy was made, in eight, a third biopsy, and finally, three underwent the fourth renal biopsy; following the results of each biopsies, immunosuppressant agents dosages were modified in order to reduce the effect of PVAN. Conclusions: In this study, the clinical and histological features of 21 kidney transplant recipients with BKV reactivation and development of PVAN are described. To date, the only treatment for PVAN consists in the reduction of immunosuppressive agents, constantly monitoring viral load.

BK Virus Nephropathy: Prevalence, Impact and Management Strategies

BK virus reactivation as a result of therapeutic immunosuppression following renal transplant can result in BK polyomavirus nephropathy and renal allograft loss. This is a complex and challenging clinical problem with a range of management options and practices reported in literature. The current standard for early diagnosis and treatment is surveillance by measuring viral DNA in blood using qPCR. Immunosuppression reduction is the cornerstone of effective management but is associated with a risk of acute rejection following treatment.

Next-generation sequencing shows marked rearrangements of BK polyomavirus that favor but are not required for polyomavirus-associated nephropathy

BACKGROUND

BKPyV is associated with polyomavirus-associated nephropathy (PVAN), a major cause of graft rejection in kidney transplant recipients (KTRs). Mutations occur in the transcriptional control region (TCR) of BKPyV, but whether they are required for the development of PVAN is not completely understood. To this end, we characterized BKPyV TCRs from KTRs to assess whether TCR mutations are associated with PVAN.

STUDY DESIGN

We analyzed urine and plasma samples of fifteen KTRs with biopsy-confirmed PVAN, presumptive PVAN, or probable PVAN in order to explore the contents of the BKPyV virome. BKPyV TCRs were amplified and deep sequenced to characterize the viral strains. Alterations in block structures and transcription factor binding sites were investigated.

RESULTS

The majority of sequences in both urine and plasma samples represented archetype BKPyV TCR. Minor populations harboring rearranged TCRs were detected in all patient groups. In one biopsy-confirmed PVAN patient rearranged TCRs predominated, and in another patient half of all reads represented rearranged sequences.

CONCLUSIONS

Although archetype BKPyV predominated in most patients, highest proportions and highest numbers of rearranged strains were detected in association with PVAN. TCR mutations seem not necessary for the development of PVAN, but immunosuppression may allow increased viral replication giving rise to TCR variants with enhanced replication efficiency.

BK virus histopathologic disease severity does not predict allograft outcome in renal transplant recipients

AIMS

BK polyomavirus nephropathy (BKPyVN) is an important cause of allograft failure after renal transplantation. Despite early screening for the virus, allograft loss from BKPyVN is still experienced in up to 14% of all renal transplant recipients. The aim of this study was to investigate the association between BKPyVN histopathologic disease severity and allograft outcome at our center.

METHODS

Kidney transplant recipients who had undergone transplantation between 2002 and 2014 with biopsy proven BKPyVN were eligible for this retrospective study. Each biopsy was re-evaluated by a single pathologist blinded to the clinical data and scored according to the Banff criteria for rejection and BKPyVN. Serum creatinine and BK viral load at the time of biopsy diagnosis as well as allograft outcomes to include allograft survival and serum BK viremia resolution were collected for each recipient to determine if BK virus histopathologic disease severity could predict allograft outcome.

RESULTS

Twenty cases of BKPyVN were identified from 1031 total renal transplants performed. There was no statistical association between allograft loss and BKPyVN histopathology (p = 0.49). There was also no statistical association between BKPyVN histopathology and BK viral load at the time of biopsy diagnosis (p = 0.38) or serum BK viremia resolution (p = 0.16).

CONCLUSIONS

BKPyVN histopathology does not appear to be useful in predicting renal allograft outcome in those recipients diagnosed with BKPyVN which is in contrast to some previously published data.

Viral infections directly involved in kidney allograft function

Modern immunosuppressive therapy has dramatically reduced the incidence of acute rejection and improved graft survival in kidney transplant patients. However, infectious complications remain an important issue. Amongst the various pathogens, viruses such as adenovirus and polyomavirus BK can directly cause acute or chronic graft dysfunction. Adenovirus mainly causes haemorrhagic cystitis and tubulointerstitial nephritis in kidney transplant patients. While patients show apparent clinical symptoms such as fever, dysuria, gross haematuria, frequency and urgency of urination, and most patients show acute graft dysfunction, these symptoms and graft dysfunction are reversible. Polyomavirus BK infection, however, is asymptomatic but graft outcome is poor if the patient develops tissue-invasive nephropathy confirmed by graft biopsy. Recently, an attempt to create a pathological classification for predicting the clinical course has been made by the Banff Working Group on Polyomavirus Nephropathy. With regards to treatment, the basic strategy is a reduction of calcineurin inhibitor and/or antimetabolites, and the effectiveness of several adjunct treatments has been investigated in several clinical trials. There are other unresolved issues, such as the diagnosis of subsequent acute rejection, the definition of remission, methods of resuming immunosuppression and long-term follow-up. Most of all, development of effective vaccines and novel drug discovery are necessary to prevent the development and progression of BKV-associated nephropathy.

T cell therapies for human polyomavirus diseases

Rapid restoration of virus-specific T immunity via adoptive transfer of ex vivo generated T cells has been proven as a powerful therapy for patients with advanced cancers and refractory viral infections such as cytomegalovirus (CMV) and Epstein-Barr virus (EBV). BK virus (BKV), John Cunningham virus (JCV), and Merkel cell carcinoma virus (MCV) are the members of the rapidly growing human polyomavirus (hPyV) family that commonly infects most healthy humans. These viruses have a clearly established potential for causing severe end-organ damage or malignant transformation, especially in individuals with weakened immunity who are unable to mount or regain endogenous T-cell responses as a result of underlying leukemia or iatrogenic immunosuppression in autoimmunity, bone marrow and solid organ transplant settings. Here we will discuss recent advances in using T-cell-based immunotherapies to save patients suffering from PyV-associated diseases including hemorrhagic cystitis, BKV virus-associated nephropathy, and JC-associated progressive multifocal leukoencephalopathy (PML). We will also review progress in the understanding of Merkel cell carcinoma (MCC) as a virally driven tumor that is amenable to immune intervention and can be targeted with adoptively transferred T cells specific for viral oncoproteins.