Ravinder K. Wali

Clinical Course of Polyoma Virus Nephropathy in 67 Renal Transplant Patients

Polyoma virus (PV) can cause interstitial nephritis and lead to graft failure in renal transplant recipients. The clinical course of patients with polyoma virus nephritis (PVN) is not well understood, partially due to its relatively low incidence. This study is a retrospective analysis of our experience over 4 yr. The specific purpose is to outline the clinical course and outcome of patients with PVN and to study the relationship between immunosuppression and the disease process. Between June 1997 and March 2001, 67 patients with graft dysfunction were found to have biopsy-proven PVN. The diagnosis was made at a mean of 12.8 +/- 9.9 mo posttransplantation. The majority of patients were men (79%) with a mean age of 54 +/- 14 yr (range, 28 to 75). All patients received immunosuppression with a calcineurin inhibitor (tacrolimus in 89% of patients). All patients except two received mycophenolate mofetil and prednisone. After the diagnosis of PVN, maintenance immunosuppression was reduced in 52 patients and remained unchanged in 15 patients. After reduction of immunosuppression, eight patients (15.3%) developed acute rejection and six (11.5%) became negative for PV in biopsy and urine. After a mean observation period of 12.6 mo (mean of 26 mo posttransplantation), 16.4% of patients had lost their grafts (8 of 52 in the reduction group and 3 of 15 in the no change group). In comparison to a case-matched polyoma virus-negative control group, the PVN patients were older (P =.0004) and there was a predominance of men (P = 0.02). Kaplan-Meier analysis demonstrated that patients with PVN had reduced graft survival compared with negative controls (P =.0004). It is concluded that PVN is a serious hazard for renal transplant recipients and contributes directly to graft loss. Antiviral drugs are needed, as the reduction of immunosuppression alone may not significantly improve graft function in patients with already established PVN. Although multiple factors probably play a role in the development of PVN, judicious use of immunosuppressive agents is indicated to minimize the occurrence of this infection.

Histological patterns of polyomavirus nephropathy: correlation with graft outcome and viral load.

Polyomavirus‐associated nephropathy (PVAN) is a significant cause of allograft loss. The diagnosis requires allograft biopsy, but the impact of the histological features on diagnosis and outcome has not been described. We studied the distribution and extent of PVAN in 90 patients. Viral cytopathic changes, tubular atrophy/fibrosis and inflammation were semi‐quantitatively scored and classified into histological patterns. The histological findings were correlated with viruria, viremia and graft survival. PVAN lesions were random, (multi‐)focal and affected both cortex and medulla. Areas with PVAN coexisted with areas of unaffected parenchyma. In 36.5% (15/41) of biopsies with multiple tissue cores, discordant findings with PVAN‐positive and ‐negative cores were observed. However, all patients with PVAN had decoy cells in urine as well as significant viruria and viremia (mean of 2.5 × 108 and 2.32 × 107 viral copies, respectively). Biopsies showing lesser degrees of renal scarring at the time of diagnosis were associated with, more likely, resolution of the infection, in response to decrease of immunosuppression (p = 0.001). More advanced tubulointerstitial atrophy, active inflammation and higher creatinine level at diagnosis correlated with worse graft outcome (p = 0.0002, 0.0001 and 0.0006). Due to the focal nature of PVAN, correlation of biopsy results with viruria and viremia are required for diagnosis.

The decade of polyomavirus BK-associated nephropathy: state of affairs.

In the last 10 years, better immunosuppression drugs have decreased the rates of acute rejection in kidney transplantation but have also led to the emergence of polyomavirus-associated nephropathy (PVAN). This occurs in 1% to 10% of patients with kidney transplantion and is caused by BK virus in more than 95% of cases. Less than 5% of cases are attributed to the JC virus. Initially, lack of recognition or late diagnosis of PVAN resulted in rapid loss of graft function in more than 50% of patients. In recent years, it has become clear that early diagnosis and timely reduction in immunosuppression is the only proven measure, which significantly affects the outcome of PVAN. Diverse interventions have been explored including the adjunctive use of cidofovir, leflunomide, fluoroquinolones, and intravenous immunoglobulins. Allograft histology is needed to definitively establish the diagnosis of PVAN, but is of limited sensitivity in the early stage of disease. Well-established techniques and protocols for systematic screening by urine cytology and quantitative molecular-genetic techniques allow now for timely intervention before irreversible parenchymal changes occur. Moreover, preemptive reduction in immunosuppression is most effective in presumptive PVAN as defined by surrogate markers (i.e., high BK virus viremia). In this setting, preservation of graft function can be considered the rule. Nevertheless, the recovery of BK virus-specific T-cell immunity may require prolonged periods during which cytopathic damage may continue to accumulate. Despite remarkable progress in the field, important challenges remain, such as the rare patient with PVAN refractory to any intervention and the newly recognized association of PVAN with urogenital tumors.

Polyomavirus BK versus JC replication and nephropathy in renal transplant recipients: a prospective evaluation.

Background. JC virus (JCV) viruria is more common than BK virus (BKV) viruria in healthy individuals but in kidney transplants (KT), polyomavirus nephropathy (PVAN) is primarily caused by BKV. Few cases of PVAN have been attributed to JCV. Systematic studies on JCV replication in KT are lacking. Methods. Out of a cohort of KT patients screened with urine cytology, patients shedding decoy cells were studied (n=103). Molecular studies demonstrated BKV, JCV, or BKV+JCV shedding in 58 (56.3%), 28 (27.2%), and 17 (16.5%), respectively. Biopsy was performed when decoy cells persisted 2 months or serum creatinine increased >20%. Results. BKV viruria was strongly associated with BKV viremia (93%), PVAN (48%, P=0.01) and graft loss (P=0.03). Higher BKV viremia correlated with graft dysfunction (P=0.01), more advanced histological pattern of PVAN (P<0.0001), and more infected cells in biopsy (P=0.0001). BKV viremia of ≥10,000 copies/mL was significantly associated with histologically confirmed PVAN (P=0.0001). Reduction of immunosuppression lead to disappearance of decoy cells in patients shedding BK (>93%). JCV viruria, was more often asymptomatic (P=0.002) and affected older patients (P=0.02). JCV PVAN was less common (21.4%) and was characterized by sparse cytopathic changes but significant inflammation and fibrosis. JCV viremia was rare (14.2%), transient, and low (mean 2.0E+03/mL). After reduction of immunosuppression decoy cells persisted in >50% of patients with JCV (P=0.0001), but no graft loss occurred. During the period of the current study, the incidence of BKV-PVAN was 5.5% and the incidence of JCV-PVAN was 0.9%. Conclusions. The data point to significant differences of BKV and JCV biology regarding replication and disease in KT patients, with important implications for screening and management.

Efficacy and Safety of Renal Tubule Cell Therapy for Acute Renal Failure

The mortality rate for patients with acute renal failure (ARF) remains unacceptably high. Although dialysis removes waste products and corrects fluid imbalance, it does not perform the absorptive, metabolic, endocrine, and immunologic functions of normal renal tubule cells. The renal tubule assist device (RAD) is composed of a conventional hemofilter lined by monolayers of renal cells. For testing whether short-term (up to 72 h) treatment with the RAD would improve survival in patients with ARF compared with conventional continuous renal replacement therapy (CRRT), a Phase II, multicenter, randomized, controlled, open-label trial involving 58 patients who had ARF and required CRRT was performed. Forty patients received continuous venovenous hemofiltration + RAD, and 18 received CRRT alone. The primary efficacy end point was all-cause mortality at 28 d; additional end points included all-cause mortality at 90 and 180 d, time to recovery of renal function, time to intensive care unit and hospital discharge, and safety. At day 28, the mortality rate was 33% in the RAD group and 61% in the CRRT group. Kaplan-Meier analysis revealed that survival through day 180 was significantly improved in the RAD group, and Cox proportional hazards models suggested that the risk for death was approximately 50% of that observed in the CRRT-alone group. RAD therapy was also associated with more rapid recovery of kidney function, was well tolerated, and had the expected adverse event profile for critically ill patients with ARF.

HIV-1-associated nephropathy and response to highly-active antiretroviral therapy

A 37-year-old African-American man with schizophrenia and bipolar disorder was admitted with psychotic symptoms after stopping his medications. Within 2 weeks of admission, his blood urea increased from 8 to 21 mmol/L and creatinine from 203 to 450 mol/L. 3 weeks later his serum sodium was 135 mmol/L, potassium 6·7 mmol/L, chloride 109 mmol/L, bicarbonate 13 mmol/L, urea 32 mmol/L, and creatinine 770 mol/L. Calculated creatinine clearance was 7 mL/min and he required haemodialysis. His blood pressure was 132/70 mm Hg, weight 77 kg, and height 162 cm. He had pharyngeal thrush, penile warts, and prominent jugular veins without peripheral oedema. His medications were olanzapine, haloperidol, sodium valproate, and lorazepam. Additional laboratory tests indicated a normal urinary sediment on microscopy, urinary protein 9·9 g/day with normal urine and serum immunoelectrophoresis. He had a mild normocytic, normochromic anaemia, with haemoglobin of 95 g/L, and a normal platelet count. Serum albumin was 14 g/L and total cholesterol 7·2 mmol/L. Tests for collagen diseases, vasculitic syndromes, or infection with hepatitis or herpes group viruses were negative, and complement levels were normal; these tests were repeated 6 weeks later and remained unchanged. HIV-1 antibodies were present on enzyme-linked immunosorbent assay and western blot. His CD4 lymphocyte count was 0·04 10/L and the CD8 count 0·42 10/L. Serum HIV-1 RNA by branched chain DNA assay was 906 000 copies per mL. An ultrasound examination was remarkable for 13·5 cm kidneys with increased echogenicity. A percutaneous kidney biopsy was done a week before the initiation of dialysis and showed changes typical of HIV-1associated nephropathy. On light microscopy a core of renal cortex had fourteen glomeruli, of which one glomerulus was globally sclerotic. The other glomeruli were normocellular but had significant tuft collapse, with more than 70% having epithelial pseudocrescents. The interstitium showed prominent microcystic tubular dilatation containing proteinaceous casts (figure, A). The vessels were unremarkable, and glomerular immunofluorescence staining was negative. Electron microscopy confirmed collapsing glomerulopathy without endocapillary hypercellularity, plus marked hypertrophy and hyperplasia of the podocytes leading to epithelial pseudocrescents. Endothelial cells contained tubuloreticular cytoplasmic inclusions. Triple antiretroviral therapy with stavudine 20 mg/day, lamivudine 50 mg/day, and nelfinavir 1250 mg twice daily was started 1 week before haemodialysis. After13 weeks of treatment and 12 weeks of haemodialysis three times per week, a 24-hour urine collection (3·5 L) contained 0·7 g protein and 10·6 mmol creatinine. 2 weeks later repeat 24hour urine tests were similar and dialysis was discontinued. A repeat percutaneous renal biopsy at that time showed 18

Retransplantation in patients with graft loss caused by polyoma virus nephropathy.

The characteristics and outcome in 10 patients who underwent retransplantation after losing their renal grafts to BK virus-associated nephropathy (BKAN) are described. The patients underwent retransplantation at a mean of 13.3 months after failure of the first graft. Nephroureterectomy of the first graft was performed in seven patients. Maintenance immunosuppression regimens after the first and second grafts were similar, consisting of a combination of a calcineurin inhibitor, mycophenolate mofetil, and prednisone. BKAN recurred in one patient 8 months after retransplantation, but stabilization of graft function was achieved with a decrease in immunosuppression and treatment with low-dose cidofovir. After a mean follow-up of 34.6 months, all patients were found to have good graft function with a mean creatinine of 1.5 mg/dL. From this collective experience from five transplant centers (although the follow-up after retransplantation was not extensive), it can be concluded that patients with graft loss caused by BKAN can safely undergo retransplantation. The risk of recurrence does not seem to be increased in comparison with the first graft.

BK polyoma virus allograft nephropathy: ultrastructural features from viral cell entry to lysis.

BK virions must enter the host cell and target their genome to the nucleus in order to complete their life cycle. The mechanisms by which the virions accomplish these tasks are not known. In this morphological study we found that BK virions localized beneath the host cell cytoplasmic membrane in 60–70‐nm, smooth (non‐coated) monopinocytotic vesicles similar to, or consistent with, caveolae. In the cytoplasm, the monopinocytotic vesicles carrying virions appeared to fuse with a system of smooth, vesicles and tubules that communicated with the rough endoplasmic reticulum and was continuous with the Golgi system. Membrane‐bound single virions and large tubulo‐reticular complexes loaded with virions accumulated in paranuclear locations. Occasional nuclei displayed virions within the perinuclear cisterna in association to the perinuclear viral accumulations. Tubular cells with mature productive infection had large nuclei, distended by daughter virions, whereas they lacked significant numbers of cytoplasmic virions. In addition to virally induced cell necrosis, there was extensive tubular cell damage (apoptosis and necrosis) in morphologically non‐infected tubules. The observed ultrastructural interactions between the BK virions and host cells are remarkably similar to viral cell entry and nuclear targeting described for SV40 virus.

BK virus-associated nephropathy in renal allograft recipients: rescue therapy by sirolimus-based immunosuppression.

Background. BK virus nephritis (BKN) in recipients of renal allografts has reemerged during the past 5 years. Despite increased incidence, therapeutic options remain limited and progression of the disease often leads to allograft failure. Methods. From May 2002 to July 2002, we performed protocol biopsies in 25 recipients of kidney allografts with progressive allograft dysfunction; three patients demonstrated unexpected histopathologic features of BKN. We tested the hypothesis that replacement of their lymphocytotoxic and nephrotoxic immunosuppression (combination of mycophenolate and tacrolimus) with sirolimus- and prednisone-based therapy can lead to disappearance of the virus without increasing the risk of acute rejection. Results. During the median follow-up of 18 months after sirolimus and prednisone therapy, decoy cells disappeared first, followed by progressive decrease in the median plasma BK virus-DNA load, and undetectable levels at the last follow-up. Patients remained free of acute rejection, and follow-up median estimated creatinine clearance increased to 67 mL/min (range 62–75 mL/min) from 52 mL/min (range 51–54 mL/min) at the time of diagnosis. Conclusions. Further studies are needed, but at present these preliminary results offer a new direction for therapeutic intervention in recipients of renal allografts with BKN.

Early Withdrawal of Calcineurin Inhibitors and Rescue Immunosuppression with Sirolimus-Based Therapy in Renal Transplant Recipients with Moderate to Severe Renal Dysfunction

Mammalian Target‐of‐Rapamycin inhibitors (mTOR inhibitors) can be used to replace the calcineurin inhibitors (CNIs) to prevent progression in chronic kidney disease (CKD) following organ transplantation. Discontinuation of tacrolimus in 136 recipients of kidney transplants with progressive renal dysfunction significantly decreased the rate of loss of estimated glomerular filtration rate (eGFR, mL/min/1.73 m2) (pre‐intervention vs. post‐intervention slopes, −0.013 vs. −0.002, p < 0.0001). Discontinuation of tacrolimus was associated with a sustained and significant improvement in graft function (pre‐eGFR vs. post‐eGFR; 26.0 ± 1.1 vs. 47.4 ± 2.1, p < 0.0001) in 74% of patients. This intervention was ineffective if the mean and (median) values of creatinine (mg/dL) and eGFR were 3.8 ± 0.2 (3.4) and 18.4 ± 1.9 (22.4), respectively, at the time of conversion therapy. During the follow‐up (range, 1.5–34.6, months), a total of 13 patients had their first acute rejection following the conversion therapy, an annual incidence of less than 10% and none of these episodes resulted in graft loss. The salutary effects of sirolimus therapy following discontinuation of tacrolimus in patients with moderate to severe graft dysfunction due to allograft nephropathy even in high‐risk patients improves kidney function and prevents acute rejection.