Polyomavirus in kidney and kidney-pancreas transplant recipients

Outcomes of Patients With Rejection Post–Polyomavirus Nephropathy

INTRODUCTION

We sought to determine the effects of rejection in renal transplant recipients with polyomavirus nephropathy (PVN).

METHODS

SCr, biopsy findings, BKV serum and urine loads (Taqman PCR), and BKV antibody titers (HA inhibition assay) were analyzed by two-sample median tests and z tests in 11 patients with median follow-up of 7.3 (2.0 to 31.5) months post-PVN. All patients underwent immunosuppression reduction (ISR) as PVN treatment.

RESULTS

Post-PVN, 3 (27%) patients had five rejection episodes, with 80% being mild. Median time to rejection was 18 (2 to 60) weeks. One hundred percent of patients who experienced post-PVN rejection also experienced rejection pre-PVN. Rejection episode treatments consisted of: none in one, increased tacrolimus in two, IVIG in one, IVIG and increased tacrolimus in one. Median viral loads in patients with post-PVN rejection versus those without rejection were not different in serum (2.01 x 10(4) vs 9.00 x 10(4) BKV copies/mL; P = .22) or urine (5.37 x 10(5) vs 8.93 x 10(6) BKV copies/mL; P = .28). Median BKV antibody titers were slightly lower (16384 vs 32768 HA units; P = .02) and median SCr values were significantly higher (2.7 vs 1.9 mg/dL, P = .0003) in patients who had experienced post-PVN rejection. Graft losses occurred in one rejection-free patient (chronic allograft nephropathy) and in one patient who experienced multiple acute rejection episodes, humoral rejection, and worsening PVN.

CONCLUSIONS

Patients who experience rejection prior to PVN are at high risk of developing rejection post-ISR and post-PVN; however, low graft loss rates may still be achieved.

BKV in simultaneous pancreas-kidney transplant recipients: a leading cause of renal graft loss in first 2 years post-transplant

With the introduction of more potent immunosuppressive agents, rejection has decreased in simultaneous pancreas/kidney transplant (SPK) recipients. However, as a consequence, opportunistic infections have increased. The purpose of this report is to outline the course of SPK patients who developed polyomavirus-associated nephropathy (PVAN). A retrospective review of 146 consecutive SPK recipients from January 1, 1996 to December 31, 2002 was performed. Immunosuppression, rejection and development of PVAN were reviewed. Nine patients were identified. All received induction with either OKT3 or thymoglobulin. Immunosuppression included tacrolimus/cyclosporine, MMF/azathioprine and sirolimus/prednisone. Two patients were treated for kidney rejection prior to the diagnosis of PVAN. Time to diagnosis was an average of 359.3 days post-transplantation. Immunosuppression was decreased but five ultimately lost function. However, none developed pancreatic abnormalities as demonstrated by normal glucose and amylase. Two underwent renal retransplantation after PVAN diagnosis and both have normal kidney function. PVAN was the leading cause of renal loss in SPK patients in the first 2 years after transplantation and is a serious concern for SPK recipients. The pancreas, however, is spared from evidence of infection, and no pancreatic rejection occurred when immunosuppression was decreased.

BK nephropathy in kidney transplant recipients treated with a calcineurin inhibitor-free immunosuppression regimen

Recently, polyomavirus-associated nephropathy (PVAN) has been reported more frequently and is emerging as an important cause of renal allograft dysfunction and graft loss. Susceptibility appears to be related to the type and intensity of pharmacologic immunosuppression but some reports have suggested a link among the development of PVAN, the treatment of rejection or maintenance with a tacrolimus-based immunosuppressive regimen. We report three cases of PVAN in patients who never received immunosuppression with calcineurin inhibitors (CNIs). Two patients received induction immunosuppression consisting of an IL-2 receptor antagonist while 1 received thymoglobulin. These 3 patients were maintained on prednisone, sirolimus and mycophenolate mofetil (MMF) and none was treated for rejection. All three patients presented with an elevated serum creatinine and demonstrated polyomavirus infection on biopsy and by blood PCR. These cases demonstrate that, unlike reports linking tacrolimus and PVAN, polyomavirus infection may develop in patients maintained on CNI-free immunosuppressive regimens and have not had episodes of rejection.

Polyomavirus nephropathy in pediatric kidney transplant recipients

Given the limited information regarding BK virus-associated nephropathy (BKVN) in pediatric kidney transplant recipients, we assessed the incidence, risk factors, clinical and virologic features of BKVN in pediatric renal transplant recipients at a single transplant center by means of a retrospective cohort study. Histologically confirmed BKVN developed in 6 of 173 (3.5%) kidney transplant recipients at a median of 15 months post-transplant (range: 4-47 months). At a median follow-up of 28 months (range: 5-32), all patients had functioning grafts with mean creatinine and GFR of 1.9 mg/dL and 58 mL/min/1.73 m2, respectively. At the time of diagnosis, all cases had viruria (median 6.1 x 10(6) copies/mL, range: 10(5) to 3.9 x 10(8) copies/mL) and viremia (median 21,000 copies/mL, range: 10,000-40,000 copies/mL). Recipient seronegativity for BKV was significantly associated with the development of BKVN (p = 0.01). BKVN is an important cause of late allograft dysfunction and is strongly associated with recipient seronegativity in pediatric kidney transplant recipients. Further studies to confirm this finding and to define the clinical utility of routine pre-transplant BKV serologic testing are warranted.

Polyomavirus nephropathy in kidney transplantation

Polyomavirus nephropathy has become an important complication in kidney transplantation, with a prevalence of 1% to 8%. Unfortunately, the risk factors for polyomavirus nephropathy and renal allograft loss are not well defined. The definitive diagnosis is made through assessment of a kidney transplant biopsy. Recently, noninvasive urine and serum markers have been used to assist in polyomavirus nephropathy diagnosis and monitoring. Primary treatment is immunosuppression reduction, but must be balanced with the risks of rejection. No antiviral treatments for polyomavirus nephropathy have been approved by the Food and Drug Administration. Although cidofovir has shown in vitro activity against murine polyomaviruses, and has been effective in some patients, it is associated with significant nephrotoxicity. Graft loss due to polyomavirus nephropathy should not be a contraindication to retransplantation; however, experience is limited. This review presents potential risk factors, screening, diagnostic and monitoring methods, therapeutic management, and retransplantation experience for polyomavirus nephropathy.

Pancreatic transplantation: Beta cell replacement

Diabetes is a leading cause of morbidity and mortality worldwide. Complications of diabetes including renal failure, retinopathy, neuropathy, and cardiovascular disease limit both survival and quality of life. Pancreatic transplantation can restore euglycemia thereby stabilizing or even reversing secondary complications of diabetes as well as improving quality of life particularly in patients with labile diabetes. Recent evidence also shows an improved survival in diabetic patients that undergo pancreatic transplantation when combined with a kidney transplant. Pancreatic transplantation should more properly be referred to as beta cell replacement as the field today encompasses both whole organ and islet cell transplantation. We have outlined herein the indications and contraindications to islet or whole organ pancreas transplantation and we have described periprocedure care and short- and long-term prognosis.

Increased kidney transplantation utilizing expanded criteria deceased organ donors with results comparable to standard criteria donor transplant

OBJECTIVE

To compare outcomes in recipients of expanded criteria donor (ECD) versus standard criteria donor (SCD) kidneys at a single center using a standardized approach with similar immunosuppression.

SUMMARY BACKGROUND DATA

Expanded criteria deceased organ donors (ECD) are a source of kidneys that permit more patients to benefit from transplantation. ECD is defined as all deceased donors older than 60 years and donors older than 50 years with 2 of the following: hypertension, stroke as the cause of death, or pre-retrieval serum creatinine (SCr) greater than 1.5 mg/dl.

METHODS

We retrospectively studied 90 recipients of adult deceased donor kidneys transplanted from October 1, 2001 to February 17, 2003, including 37 (41%) from ECDs and 53 (59%) from SCDs. ECD kidneys were used by matching estimated renal functional mass to recipient need, including the use of dual kidney transplants (n = 7). ECD kidney recipients were further selected on the basis of older age, HLA-matching, low allosensitization, and low body mass index. All patients received a similar immunosuppressive regimen. Minimum follow up was 9 months.

RESULTS

There were significant differences in donor and recipient characteristics between ECD and SCD transplants. Patient (99%) and kidney graft survival (88%) rates and morbidity were similar between the 2 groups, with a mean follow-up of 16 months. Initial graft function and the mean 1-week and 1-, 3-, 6-, 12-, and 18-month SCr levels were similar among groups.

CONCLUSIONS

The use of ECD kidneys at our center effectively doubled our transplant volume within 1 year. A systematic approach to ECD kidneys based on nephron mass matching and nephron sparing measures may provide optimal utilization with short-term outcomes and renal function comparable to SCD kidneys.

Polyomavirus-Associated nephropathy in simultaneous Kidney-Pancreas transplant recipients: a Single-Center experience

BACKGROUND

With the introduction of more potent immunosuppressive agents, rejection rates have decreased markedly in simultaneous pancreas-kidney transplant (SPK) recipients. However, with more intense immunosuppression, opportunistic infections such as polyoma virus have been more frequent. The purpose of this article is to outline the clinical course of SPK patients who developed documented polyoma infection in the transplanted kidney.

METHODS

A retrospective review of 146 consecutive SPK recipients from 1996 to 2002 was performed. Induction and maintenance immunosuppression, surgical complications, rejection episodes, and opportunistic infections were reviewed. Patients who developed biopsy-proven polyoma virus infection in the renal allograft were identified.

RESULTS

Nine patients (6%) were identified who developed polyoma. All had received induction therapy with either OKT3 (5 mg/d for 10.5 days) or thymoglobulin (5.7 mg/kg). Patients without polyoma had received similar induction. Maintenance immunosuppression included Prograf/MMF in six patients, CsA/MMF in two, and CsA/azathioprine in one. Time to diagnosis was an average of 359.3 days (range 136 to 836) after transplantation. Two patients had undergone treatment for kidney rejection prior to the diagnosis of polyoma. Immunosuppression was decreased in all patients when polyoma was identified, and more recently Cidofovir has been administered. Despite these interventions, five of the nine lost kidney function (creatinine > 5.0 or resumption of dialysis). However, none of the nine developed pancreatic abnormalities as demonstrated by normal blood glucose and amylase and no requirement for exogenous insulin. Two patients underwent LRRT more than 1 year after polyoma diagnosis; both have normal kidney function (Cr < 1.5 mg/dL) at 4 years of follow-up. Polyoma virus was the leading cause of renal loss in this cohort of patients.

CONCLUSIONS

Polyoma is a serious concern for SPK transplant recipients. The pancreas, however, is spared from clinical evidence of infection, and no rejection was noted when immunosuppression was decreased. These graft losses appear to be a penalty of more potent immunosuppression, and a better treatment strategy is needed to prevent renal graft loss when polyoma is diagnosed. Retransplantation can be considered based on our limited experience.

Polyomavirus BK

Polyomavirus hominis 1, better known as BK virus (BKV), infects up to 90% of the general population. However, significant clinical manifestations are rare and limited to individuals with impaired immune functions. BKV has been associated with diverse entities such as haemorrhagic cystitis, ureteric stenosis, vasculopathy, pneumonitis, encephalitis, retinitis, and even multi-organ failure. In addition, BKV has been implicated in autoimmune disease and possibly cancer. Due to high prevalence and frequent reactivation, the role of BKV in some of these pathologies has been difficult to define. Development of BKV diseases is likely to require complementing determinants in the host, the target organ, and possibly the virus, that are subject to modulators such as immunosuppression. These complex aspects are highlighted in polyomavirus-associated nephropathy (PAN), an emerging disease in renal allograft recipients that may jeopardise the progress in renal transplantation accomplished in the past 10 years. Intervention is difficult due to the lack of specific antivirals and relies mostly on improving immune control. Diagnostic strategies using urine cytology and BKV load measurements in plasma have led to earlier diagnosis of PAN, which increased the success rate of intervention. Case series suggest that cidofovir might be effective, especially when combined with reduced immunosuppression.

Renal transplantation and polyomavirus infection: recent clinical facts and controversies

Although many articles have been published on polyomavirus-induced pathologies in transplant recipients, our knowledge regarding their clinical aspects remains relatively limited. In fact, the number of questions and controversies on the subject seems even to be increasing as new publications continue to appear. This article presents some of these controversies through a brief review of recent clinical facts about the three polyomaviruses that infect humans--JC virus, simian virus 40, and BK virus--as they relate to renal transplantation.