BK virus in solid organ transplant recipients: an emerging syndrome

Low 25-Hydroxyvitamin D Post-Kidney Transplant Is Associated with Increased Risk of BK Polyomavirus-Associated Nephropathy

BK viremia (BKPyV-DNAemia) and nephropathy (BKPyVAN) are significant causes of morbidity and mortality in kidney transplant recipients (KTRs). Vitamin D supports immune function, yet low 25-hydroxyvitamin D [25(OH)D] is common among KTRs. The association between serum 25(OH)D, measured 61 days to 2 years post-transplant, and subsequent incident BKPyV-DNAemia and BKPyVAN was examined in KTRs without previous BKPyV-DNAemia or BKPyVAN, respectively. Out of 3308 KTRs, 399 (12%) were vitamin D deficient [25(OH)D ≤ 20 ng/mL], and 916 (27.7%) were insufficient [25(OH)D 21-29 ng/mL]. A total of 184 KTRs developed BKPyV-DNAemia and 44 developed BKPyVAN. The incidence rate (/100 person-years) for BKPyV-DNAemia was 2.88 in the 25(OH)D sufficient group, 2.22 in the insufficient group, and 2.37 in the deficient group. The incidence rate (/100 person-years) for BKPyVAN was 0.30 in the 25(OH)D sufficient group, 0.75 in the insufficient group, and 1.28 in the deficient group. Vitamin D deficiency (adjusted hazard ratio [aHR] compared to 25(OH)D sufficiency: 3.92; 95% CI: 1.66-9.23) and insufficiency (aHR: 2.22; 95% CI: 1.11-4.45) remained significantly associated with the incidence of BKPyVAN after adjustment for baseline characteristics. Low serum 25(OH)D was associated with an increased risk of BKPyVAN but not BKPyV-DNAemia.

Observations on hydronephrosis after pig kidney transplantation in baboons

We have seen hydronephrosis (obstructive nephropathy) at necropsy in 3 of 11 (21%) genetically-engineered pig kidneys that functioned in baboons for >36 days, even when the clinical and histopathological features of rejection were minimal. We briefly report one such case and illustrate the macroscopic and microscopic appearances of such a kidney and ureter. The causes of the observed changes remain uncertain. In our small experience, there seems to be no correlation between the development of hydronephrosis and (i) the surgical technique, (ii) the genotype of the pig, (iii) the length of the pig ureter, or (iv) the immunosuppressive and anti-inflammatory therapy administered. We suggest that the distal ureteric thickening may be the result of an inflammatory response. In two cases, we resolved the problem by carrying out a secondary side-to-side anastomosis between the proximal pig ureter and the baboon bladder.

Kidney Transplant-Associated Viral Infection Rates and Outcomes in a Single-Centre Cohort

BACKGROUND

Opportunistic infections remain a significant cause of morbidity and mortality after kidney transplantation. This retrospective cohort study aimed to assess the incidence and predictors of post-transplant DNA virus infections (CMV, EBV, BKV and JCV infections) in kidney transplant recipients (KTR) at a single tertiary centre and evaluate their impact on graft outcomes.

METHODS

KTR transplanted between 2000 and 2021 were evaluated. Multivariate logistic regression analysis and Cox proportional hazard analyses were used to identify factors associated with DNA virus infections and their impact on allograft outcomes respectively. A sub-analysis of individual viral infections was also conducted to describe the pattern, timing, interventions, and outcomes of individual infections.

RESULTS

Data from 962 recipients were evaluated (Mean age 47.3 ± 15 years, 62% male, 81% white). 30% of recipients (288/962) had infection(s) by one or more of the DNA viruses. Individually, CMV, EBV, BKV and JCV viruses were diagnosed in 13.8%. 11.3%, 8.9% and 4.4% of recipients respectively. Factors associated with increased risk of post-transplant DNA virus infection included recipient female gender, higher number of HLA mismatch, lower baseline estimated glomerular filtration rate (eGFR), CMV seropositive donor, maintenance with cyclosporin (rather than tacrolimus) and higher number of maintenance immunosuppressive medications. The slope of eGFR decline was steeper in recipients with a history of DNA virus infection irrespective of the virus type. Further, GFR declined faster with an increasing number of different viral infections. Death-censored graft loss adjusted for age, gender, total HLA mismatch, baseline eGFR and acute rejection was significantly higher in recipients with a history of DNA virus infection than those without infection (adjusted hazard ratio (aHR, 1.74, 95% CI, 1.08-2.80)). In contrast, dialysis-free survival did not differ between the two groups of recipients (aHR, 1.13, 95% CI, 0.88-1.47).

CONCLUSION

Post-transplant DNA viral infection is associated with a higher risk of allograft loss. Careful management of immunosuppression and close surveillance of at-risk recipients may improve graft outcomes.

[Ureteral stenosis following hematopoietic stem cell transplantation: A case report]

Ureteral stenosis is a comparatively rare complication following hematopoietic stem cell transplantation (HSCT). The etiology is still unclear and most believe that this may be due to the reactivation of BK virus in a state of immunodeficiency. In the later stages of ureteral stenosis with scarring, invasive interventions must be taken to relieve the hydronephrosis. Common treatments, such as D-J stent placement and permanent nephrostomy may not only entail the risk of infection, but also seriously affect the quality of life. Few cases of surgical intervention have been reported. In this article, a 25-year-old female was admitted to Peking University First Hospital suffering from recurrent flank pain. Seven years before, she developed hemorrhagic cystitis and bilateral urethritis 40 days after allogeneic HSCT. After continuous bladder irrigation and antiviral therapy, the left-sided hydronephrosis gradually alleviated while the right-sided one did not improve. D-J stents were used for urine drainage for 7 years before percuta-neous nephrostomy. Preoperative antegrade pyelography revealed significant hydronephrosis in the right kidney with long stricture of proximal-middle ureter. After comprehensive decision, she underwent ileal ureter replacement. The operation was successful. The segmental lesion was dissected and the scar tissue was removed. A 25 cm intestinal tube was isolated to connect the pelvis and bladder. An anti-reflux nipple was created at the distal end of ileal ureter to prevent the potential infection. The blood loss was minimal. After surgery, the drainage tube was removed in 2 weeks, the nephrostomy tube and the D-J stent was removed in 3 months. Follow-up mainly included clinical assessment, serologic testing, renal ultrasonography, blood gas analysis and radiological examination. During the follow-up of 6 years, she was symptom-free and no postoperative complications occurred. The serum creatinine level was stable. No hydronephrosis was observed under ultrasonography. Obvious peristaltic waves and ureteral jets of the ileal ureter was confirmed on cine magnetic resonance urography. To sum up, ureteral stenosis after HSCT is relatively rare. Obstruction caused by scarring is usually irreversible and surgical intervention should be designed according to the location and length of the lesion. Ileal ureter replacement can be a safe, feasible and effective method to solve this kind of complex stricture.

Presence of decoy cells for 6 months on urine cytology efficiently predicts BK virus nephropathy in renal transplant recipients

OBJECTIVES

To investigate the association between duration of consecutive presence of decoy cells on urine cytology and BK virus nephropathy after kidney transplantation.

METHODS

In total, 121 kidney transplant recipients were retrospectively evaluated. The best duration of consecutive presence of decoy cells that could be used to predict BK virus nephropathy was analyzed using the area under the curve for each duration, and recipients were divided into two groups based on the best predictive performance. The effectiveness of SV40 immunostaining on urinary cytology was also analyzed.

RESULTS

In total, 2534 urine specimens as well as SV40 immunostaining in 2241 urine specimens were analyzed. Six consecutive months of decoy cell positivity had the best predictive performance for BK virus nephropathy (area under the curve = 0.832). The incidence of BK virus nephropathy in recipients with positive decoy cells for 6 months or more consecutive months (5/44) was significantly higher than in those who had positive decoy cells for less than 6 months (0/77; P = 0.005). Decoy cell positivity had a sensitivity, specificity, positive predictive value, and negative predictive value for BK virus nephropathy of 100%, 66%, 11%, and 100% respectively. SV40 immunostaining provided slightly better specificity (68%) and positive predictive value (12%).

CONCLUSIONS

The detection of decoy cells at 6 months or more on urine cytology had high predictive value for BK virus nephropathy in kidney transplant recipients. SV40 immunostaining on urine cytology added minimal diagnostic accuracy.

Kidney injury and disease in patients with haematological malignancies

Acute kidney injury (AKI) is common in patients with cancer, especially in those with haematological malignancies. Kidney injury might be a direct consequence of the underlying haematological condition. For example, in the case of lymphoma infiltration or extramedullary haematopoiesis, it might be caused by a tumour product; in the case of cast nephropathy it might be due to the presence of monoclonal immunoglobulin; or it might result from tumour complications, such as hypercalcaemia. Kidney injury might also be caused by cancer treatment, as many chemotherapeutic agents are nephrotoxic. High-intensity treatments, such as high-dose chemotherapy followed by haematopoietic stem cell transplantation, not only increase the risk of infection but can also cause AKI through various mechanisms, including viral nephropathies, engraftment syndrome and sinusoidal obstruction syndrome. Some conditions, such as thrombotic microangiopathy, might also result directly from the haematological condition or the treatment. Novel immunotherapies, such as immune checkpoint inhibitors and chimeric antigen receptor T cell therapy, can also be nephrotoxic. As new therapies for haematological malignancies with increased anti-tumour efficacy and reduced toxicity are developed, the number of patients receiving these treatments will increase. Clinicians must gain a good understanding of the different mechanisms of kidney injury associated with cancer to better care for these patients.

Prospective analysis of BKV hemorrhagic cystitis in children and adolescents undergoing hematopoietic cell transplantation

BK virus is one of the most common causes of hemorrhagic cystitis (HC) in children undergoing hematopoietic cell transplantation (HCT). Viruses can be found in urine and serum samples of immunocompromised patients. Malignant diseases, age, cell source, day of granulocyte reconstitution, conditioning regimen, or use of total body irradiation may play an important role in BKV epidemiology, development of hemorrhagic cystitis course, and outcome. The aim of this study was to evaluate the incidence, clinical course, and risk factors for BKV-HC in children undergoing HCT. A total number of 133 patients who were prospectively tested for BKV colonization/infection were enrolled into this multicenter analysis. Episodes of BKV-HC occurred in 36/133 (27%) enrolled subjects. In a univariate analysis for BKV-HC incidence, the following factors were significant: age >5 years, peripheral blood transplantation, matched unrelated donor (MUD) transplantation, busulfan-cyclophosphamide-melphalan conditioning regimen, and acute myeloblastic leukemia (AML) diagnosis. Presence of acute graft-versus-host disease (aGVHD) in liver and gut GVHD was a significant risk factor of BKV-HC. No BKV-attributed deaths were reported. In multivariate analysis, the incidence of HC was significantly higher in patients with AML, age >5 years, MUD transplants, and children with GVHD. HC is a frequent complication after HCT among children causes prolonged hospitalization but rarely contributes to death. We identified risk factors of BKV-HC development in children, with focus on aGVHD: we concluded that excessive immune reaction connected with GVHD and immunosuppression drugs might play a pivotal role in the development of BKV-HC.

Advances in BK Virus Complications in Organ Transplantation and Beyond

Reactivation of BK virus (BKV) remains a dreaded complication in immunosuppressed states. Conventionally, BKV is known as a cause for BKV-associated nephropathy and allograft dysfunction in kidney transplant recipients. However, emerging studies have shown its negative impact on native kidney function and patient survival in other transplants and its potential role in diseases such as cancer. Because BKV-associated nephropathy is driven by immunosuppression, reduction in the latter is a convenient standard of care. However, this strategy is risk prone due to the development of donor-specific antibodies affecting long-term allograft survival. Despite its pathogenic role, there is a distinct lack of effective anti-BKV therapeutics. This limitation combined with increased morbidity and health care cost of BKV-associated diseases add to the complexity of BKV management. While summarizing recent advances in the pathogenesis of BKV-associated nephropathy and its reactivation in other organ transplants, this review illustrates the limitations of current and emerging therapeutic options and provides a compelling argument for an effective targeted anti-BKV drug.

Infection in Kidney Transplant Recipients

In organ transplant recipients, impaired inflammatory responses suppress the clinical and radiologic findings of infection. The possible etiologies of infection are diverse, ranging from common bacterial and viral pathogens that affect the entire community to opportunistic pathogens that cause invasive disease only in immunocompromised hosts. Antimicrobial therapies required to treat established infection are often complex, with accompanying risks for drug toxicities and drug interactions with the immunosuppressive agents used to maintain graft function. Rapid and specific diagnosis is essential for successful therapy. The risk of serious infections in the organ transplant patient is largely determined by the interaction between two factors: the patient’s epidemiologic exposures and the patient’s net state of immunosuppression. The epidemiology of infection includes environmental exposures and nosocomial infections, organisms derived from donor tissues, and latent infections from the recipient activated with immunosuppression. The net state of immune suppression is a conceptual framework that measures those factors contributing to risk for infection: the dose, duration, and temporal sequence of immunosuppressive drugs; the presence of foreign bodies or injuries to mucocutaneous barriers; neutropenia; metabolic abnormalities including diabetes; devitalized tissues, hematomas, or effusions postsurgery; and infection with immunomodulating viruses. Multiple factors are present in each host. A timeline exists to aid in the development of a differential diagnosis for infection. The timeline for each patient is altered by changes in prophylaxis and immunosuppressive drugs. For common infections, new microbiologic assays, often nucleic acid based, are useful in the diagnosis and management of opportunistic infections.

BK viremia is not associated with adverse outcomes in the absence of BK nephropathy

There are limited data regarding the association of different levels of BK viremia and BK nephropathy (BKN), and graft outcomes. We studied the BK plasma PCR levels of all kidney transplant recipients (KTR) transplanted at our institution between 01/01/2006 and 06/30/2014. Patients were divided into groups based on their highest BK plasma PCR level within the first year following transplantation: undetectable, low (<1000 copies/mL), moderate (1000-10 000 copies/mL), high (>10 000-100 000 copies/mL), very high (>100 000 copies/mL), and those that had biopsy-proven BKN. There were a total of 1146 KTR during the study period: 813 with undetectable BK levels and 333 with any detectable BK level (87 with low, 79 with moderate, 88 with high, 34 with very high level BK, and 45 that had BKN). Compared to KTR with an undetectable BK level, incidence of mortality, graft failure, rejections,and infections were not significantly different for those with low, moderate, high, or very high BK level. Patients with BKN had a higher rate of infection and higher rates of total graft failure or death-censored graft failure compared to those with undetectable BK levels. BK viremia in the absence of BKN does not significantly increase the risk of rejection, infections, or graft failure compared to an undetectable BK level.

BK virus: microbiology, epidemiology, pathogenesis, clinical manifestations and treatment

Background: BK virus infection is common but is usually asymptomatic. However, it can become life threatening as severe hemorrhagic cystitis (HC) or the polyomavirus-associated nephropathy (PVAN) particularly in immune compromised and transplant recipients. Some investigators have studied the pathophysiology and there are anecdotal and uncontrolled studies of therapy with few conclusions allowing treatment guidelines. Objectives: Summarize literature review of current knowledge concerning the nature, epidemiology, pathophysiology, diagnosis and treatment of this common virus infection. Results: HC is a not uncommon and often misdiagnosed infection from BK virus. It is usually self limited but can become life threatening in immune compromised patients. PVAN threatens survival of transplanted kidneys and is difficult to differentiate from rejection without sophisticated molecular diagnostic technology. We have sufficient information for making a diagnosis of BK virus disease by using clinical, serological and molecular technology. Studies using manipulation of immunosuppression and a variety of antiviral agents, including cidofovir, leflunomide, intravenous immunoglobulin, vidarabine, fluroquinolones, have been published but most were uncontrolled reports of few cases. Cidofovir offers some promise but more must be learned before there is hope for evidence-based treatment guidelines.

De novo donor-specific antibody following BK nephropathy: The incidence and association with antibody-mediated rejection

BACKGROUND AND OBJECTIVES

The risk of de novo donor-specific antibody (dnDSA) development following BK viremia (BKV) or nephropathy (BKN) after kidney transplant remains unclear. We aimed to evaluate the relationships among dnDSA, BKV (BK blood PCR > 15 000 copies), BKN, antibody-mediated rejection (AMR), and allograft loss.

PATIENTS AND METHODS

We performed a retrospective cohort study of 904 solitary kidney transplant recipients transplanted between 10/2007 and 5/2014. Cox proportional hazards regression with time-dependent covariates were used to assess the relationships among BKN, isolated BKV, dnDSA, and the subsequent risk of AMR and allograft loss.

RESULTS

In multivariate analysis, we observed that BKN, but not BKV was a risk factor for dnDSA (HR, 3.18, P = .008). Of the patients with BK nephropathy, 14.0% (6/43) developed dnDSA, which occurred within 14 months of BK diagnosis. DnDSA in this setting remains a risk factor for subsequent AMR (HR 4.75, P = .0001) and allograft loss (HR 2.63, P = .018).

CONCLUSIONS

BKN is an independent risk factor for development of dnDSA. Improved understanding of the characteristics of patients with BKN who are at highest risk for development of dnDSA would be valuable to customize immunosuppression reduction in this population.

Hemorrhagic Cystitis in a Liver Transplant Recipient Secondary to BK Virus

The association between BK virus infection and hemorrhagic cystitis (HC) in hematopoietic stem cell transplant (HSCT) recipients is well established. However, BK virus-associated HC has not been described in liver transplant (LT) recipients. We present a case of BK virus-associated HC in a LT recipient. Our patient presented with worsening liver function tests 2 years after transplantation and was found to have acute cellular rejection. He was treated with increased immunosuppression and subsequently developed hematuria. He was eventually diagnosed with BK virus-associated HC.

Management of Opportunistic Infections in Solid-Organ Transplantation

Solid-organ transplantation is often the last alternative in many patients with end-stage organ disease. Although advances in immunosuppressive regimens, surgical techniques, organ preservation, and overall management of transplant recipients have improved graft and patient survival, infectious complications remain problematic. Bacterial, fungal, viral, and parasitic infections are implicated after transplantation depending on numerous factors, such as degree of immunosuppression, type of organ transplant, host factors, and period after transplantation. Proper prophylactic and treatment strategies are imperative in the face of chronic immunosuppression, nosocomial and community pathogens, emerging drug resistance, drug-drug interactions, and medication toxicities. This review summarizes the pathophysiology, incidence, prevention, and treatment strategies of common post-transplant infections.

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.

BK Virus in Kidney Transplantation: A Case Study

Prevention as well as treatment of viral infections in transplant recipients relies on minimal immunosuppressive therapy consistent with graft survival and the use of antiviral therapies in proportion to perceived risk. BK virus creates an even greater challenge in posttransplant management and graft survival because of difficulty in diagnosing and treatment. BK nephropathy develops in 1% to 5% of transplant recipients, with loss of allograft function occurring in 50% of the cases. We present a case of a 67-year-old man who developed BK virus allograft nephropathy 9.5 months after transplantation. His allograft function was extended through rigorous treatment with an antiviral agent, reduction of immunosuppressant, and monitoring in an outpatient setting.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.

Risk Factors for BK Polyoma Virus Treatment and Association of Treatment With Kidney Transplant Failure: Insights From a Paired Kidney Analysis

BACKGROUND

Identification of risk factors for BK polyoma virus (BKPyV) without confounding by donor factors and era effects in paired analysis may inform strategies to prevent BKPyV.

METHODS

In this analysis of 21,575 mate kidney pairs in the Scientific Registry of Transplant Recipients between 2004 and 2010, the presence of a treatment code for BKPyV virus in follow-up forms was used to identify pairs in which 1 of 2 mate kidneys was treated (discordant treatment) or both mate kidneys were treated (concordant treatment).

RESULTS

Among 1975 discordant pairs, younger than 18 years or 60 years or older, male sex, HLA mismatch or 4 greater, acute rejection, and depleting antibody induction had a higher odds of treatment, whereas diabetes and sirolimus had a lower odds of treatment, and treatment was associated with a higher risk of allograft failure (hazards ratio, 2.01; 95% confidence interval, 1.63-2.48). The rate of concordant treatment (0.81%) was 2.8 times higher than expected. Concordant treatment was associated with nonwhite donor ethnicity, donation after circulatory death, transplantation after 2008, and transplantation of mate kidneys in the same center.

CONCLUSIONS

This analysis of kidneys from the same donor in which only 1 transplant was treated for BKPyV identifies specific risk factors (age <18 or ≥ 60 years, male sex, depleting antibody, HLA mismatch ≥ 4) for BKPyV and provides an estimate of the BKPyV-associated risk of allograft failure (hazards ratio = 2.01) without confounding by donor factors or era effects. The higher than expected rate of concordant treatment suggests the importance of donor factors in BKPyV pathogenesis and warrants further study.

BK Virus Infection in Kidney Transplantation: A Case for Early Intervention

The prognosis for renal allograft survival in a patient with BK virus–associated nephropathy is distressing because nearly 50% of affected grafts are lost. With these statistics in mind, attempting clinical intervention before BK virus disease develops seems appropriate. Noninvasive screening tools such as tests to detect decoy cells in urine can enable diagnosis of BK viral infection in its early stages. Although it is not entirely clear which patients with BK infection will have BK disease develop, it may be possible to intervene in this early warning period to prevent the further development of BK virus–associated nephropathy. We present a case of a 50-year-old man in whom asymptomatic BK viruria developed 6 weeks after he received a non-HLA matched kidney from a deceased donor. This BK viruria was accompanied, subsequently, by an unexplained increase in serum creatinine level 2 months after transplantation. Following a change in his immunosuppressive regimen as therapy for presumed renal allograft dysfunction associated with BK viral infection, the decoy cells in his urine disappeared and his creatinine levels stabilized.

Outcome after Desensitization in HLA or ABO-Incompatible Kidney Transplant Recipients: A Single Center Experience

BACKGROUND

The shortage of deceased donors led to an increase of living donor kidney (LDK) transplantations performed in the presence of donor-specific antibodies (DSA) or ABO incompatibility (ABOi) using various desensitization protocols.

METHODS

We herein analyzed 26 ABOi and 8 Luminex positive DSA patients who were successfully desensitized by anti-CD20, antigen-specific immunoadsorption and/or plasmapheresis to receive an LDK transplant. Twenty LDK recipients with non-donor-specific HLA-antibodies (low risk) and 32 without anti-HLA antibodies (no risk) served as control groups.

RESULTS

1-year graft survival rate and renal function was similar in all 4 groups (creatinine: 1.63 ± 0.5 vs 1.78 ± 0.6 vs 1.64 ± 0.5 vs 1.6 ± 0.3 mg/dl in ABOi, DSA, low risk and no risk group). The incidence of acute T-cell mediated rejections did not differ between the 4 groups (15% vs 12, 5% vs 15% vs 22% in ABOi, DSA, low risk and no risk), while antibody-mediated rejections were only found in the DSA (25%) and ABOi (7.5%) groups. Incidence of BK nephropathy (BKVN) was significantly more frequent after desensitization as compared to controls (5/34 vs 0/52, p = 0.03).

CONCLUSION

We demonstrate favorable short-term allograft outcome in LDK transplant recipients after desensitization. However, the desensitization was associated with an increased risk of BKVN.

BK Virus Nephropathy in Heart Transplant Recipients

Polyomavirus-associated nephropathy (PVAN) has become an important cause of kidney failure in kidney transplant recipients. PVAN is reported to affect 1% to 7% of kidney transplant recipients, leading to premature transplant loss in approximately 30% to 50% of diagnosed cases. PVAN occurring in the native kidneys of solid-organ transplant recipients other than kidney only recently has been noted. We report 2 cases of PVAN in heart transplant recipients, which brings the total of reported cases to 7. We briefly review the literature on the hypothesized causes of PVAN in kidney transplant recipients and comment on whether these same mechanisms also may cause PVAN in other solid-organ transplant recipients. PVAN should be considered in the differential diagnosis when evaluating worsening kidney function. BK viremia surveillance studies of nonkidney solid-organ recipients should be conducted to provide data to assist the transplantation community in deciding whether regular monitoring of nonkidney transplant recipients for BK viremia is indicated.

Treatment of BK virus-associated nephropathy with CMX001 after kidney transplantation in a young child

NC, with renal failure secondary to bilateral dysplastic kidneys, received an LRD renal transplant (tx) at 17 months of age. Her early post-tx course was complicated by persistently elevated blood polyoma BK virus DNA loads. A protocol biopsy at six months post-transplant revealed BKVAN. Blood viral loads did not respond to decreased immunosuppression or treatment with ciprofloxacin and leflunomide. Six months post-tx, her serum creatinine began to rise and we sought experimental therapy to prevent the loss of her graft. At seven months post-tx, with FDA approval under an eIND, the patient was started on a 36-wk course of treatment with the investigational drug. The patient is now more than 24 months after stopping treatment with CMX. BKV viral DNA loads remain at low, but still detectable levels. Urine viral loads have declined, but remain elevated. EBV DNA loads become undetectable. The patient's serum creatinine has declined back to a baseline of 0.5-0.7 mg/dL and has been stable for two yr. Renal function was preserved in association with the use of CMX001 to treat BKV nephropathy in a young pediatric kidney transplant recipient. There were no serious adverse events associated with the use of CMX001. This novel medication may be of value in the treatment of BKVAN in pediatric renal transplant recipients.

The kidney effects of hematopoietic stem cell transplantation

Hematopoietic stem cell transplant (HSCT) patients are at risk for acute kidney disease and CKD, which confer excess morbidity and mortality in this patient population. A main cause of acute kidney injury (AKI) in stem cell recipients is prerenal azotemia, but acute tubular necrosis (ATN), obstruction, marrow transfusion toxicity, and hepatic sinusoidal obstruction syndrome also contribute. AKI is an important risk factor for death and CKD among HSCT survivors. CKD is a growing complication of HSCT as more patients are transplanted and survival improves. For most patients, the exact etiology of CKD is never identified, but graft vs host disease and thrombotic microangiopathy are important diagnoses to consider. Stem cell transplant patient survival on dialysis is generally poor, but kidney transplantation is a safe and reasonable option for HSCT recipients who progress to ESRD.

Obstructive uropathy is associated with polyomavirus viremia in pediatric kidney transplantation

BKVN leads to allograft dysfunction following kidney transplantation and is preceded by BK viremia. Studies in pediatric kidney transplant recipients reveal an incidence of viruria ranging from 18% to 33%, viremia 6-16%, and BKVN 2-8%. Specific risk factors have not been clearly elucidated. Retrospective chart review of pediatric kidney transplants performed from January 2005 through December 2009; to identify risk factors associated with BK viremia in pediatric kidney transplant recipients from a single center. Of the 93 patients who received kidney transplants in the study period, 22 (24%) developed BK viruria, including 12 (13%) who developed viremia. One patient with viremia (1.6%) had BKVN. Obstructive uropathy was identified as the cause of ESKD in 22 (24%) of all recipients. 27% (n = 6) of these 22 patients developed viremia, while only 8.5% (6/71) with ESKD from another cause had viremia (p = 0.001). No other examined variable differed between the two groups. Although the overall incidence was no higher than other reported series, we identified that BK disease was more frequent in children with OU. A higher index of suspicion for invasive BK disease is necessary in patients with OU who receive kidney allografts. Transplant protocols may need to consider underlying cause of ESKD when designing screening protocols for BK disease in children after kidney transplantation.

Detection of polyomavirus BK reactivation after renal transplantation using an intensive decoy cell surveillance program is cost-effective

BACKGROUND

Reactivation of polyomavirus BK (BKV) after renal transplantation can lead to allograft dysfunction or loss with early detection improving outcomes. Current guidelines recommend quantitative polymerase chain reaction for surveillance; however, urinary decoy cell detection is a potentially cost-effective alternative. We present the outcomes from an early intensive BKV surveillance program using decoy cell detection for initial screening starting 2 weeks after transplantation.

METHODS

Records for all recipients of kidney (n=211) or simultaneous kidney and pancreas (n=102) transplants performed over 2 years in a single center were reviewed. Follow-up was for a minimum of 1 year. Urine cytology screening was performed fortnightly from 0 to 3 months after transplantation, monthly from 3 to 6 months then every 2 months from 6 to 12 months.

RESULTS

Decoy cell positivity occurred in 56 of 313 patients (17.9%) with sustained decoy cell positivity (≥2 positive urine samples >2 weeks apart) present in 32 patients (10.2%). Twenty-four patients (7.6%) became viremic and three patients (1%) developed polyoma virus nephropathy. The median time after transplantation until decoy cell positivity was 78 days, decreasing to 67 days for patients with sustained positivity and 57 days for patients who developed polyoma virus nephropathy. No grafts were lost due to BKV during the study period. Decoy cell screening resulted in savings of approximately £135,000 over 2 years, when compared with routine surveillance by quantitative polymerase chain reaction.

CONCLUSIONS

Clinically significant BKV reactivation occurs early after transplantation and can be reliably detected by decoy cell screening. A surveillance strategy for detecting BKV reactivation based on urine cytology is cost-effective.

Increase of infectious complications in ABO-incompatible kidney transplant recipients--a single centre experience

BACKGROUND

Due to the shortage of deceased donors ABO-incompatible (ABOi) living kidney transplantation has become a popular alternative to deceased kidney transplantation. In recent years, recipient desensitization with a combination of anti-CD20 treatment (rituximab), antigen-specific immunoadsorptions (IA) and intravenous immunoglobulin (IVIG), led to promising short-term and intermediate-term results. However, little is known about the impact of this intensified desensitization protocol on the risk of surgical and infectious complications.

METHODS

We retrospectively analysed 21 consecutive recipients who underwent ABOi renal transplantation. Pre-transplant desensitization included administration of rituximab (375 mg/m(2)), mycophenolate mofetil (MMF), tacrolimus and prednisolone 4 weeks prior of scheduled transplantation as well as IA and IVIG. Forty-seven patients who underwent ABO-compatible (ABOc) renal transplantation served as the control group. Medical records and electronic databases were reviewed for patient and graft survival, renal function, rate of rejections, viral and bacterial infections as well as for surgical complications (SCs) post-transplantation.

RESULTS

All patients showed an immediate graft function. During a mean follow-up of 15.7 ± 8.3 months (interquartile range 11.9) patient survival was 95 and 98% in the ABOi and ABOc group, respectively. Allograft survival and function, as assessed by serum creatinine levels and calculated glomerular filtration rate at 1 year, did not differ between ABOi and ABOc recipients. Furthermore, the rate of biopsy-proven acute rejections was comparable between the two groups. However, there was a trend towards more SCs within the ABOi group (29 versus 11%, non-significant). In addition, the rate of viral infections including cytomegalovirus, Herpes simplex virus, Varicella zoster virus and polyoma virus was significantly increased among the ABOi recipients (50 versus 21%; P = 0.038) despite comparable tacrolimus trough levels and MMF and steroid doses.

CONCLUSIONS

Our results, in line with the extended experience of other groups, demonstrate favourable short-term allograft survival and function after ABOi renal transplantation after desensitization with antigen-specific IA, IVIG and rituximab. However, the intensified desensitization was associated with an increased risk of infectious complications. This observation prompted us to briefly escalate the desensitization protocol in ABOi kidney recipients in our centre.

Maintenance immunosuppressive agents as risk factors for BK virus nephropathy: a case-control study

BACKGROUND

The specific role of different immunosuppressive agents as risk factors for BK virus nephropathy (BKN) has not been well studied.

METHODS

In this case-control study, we examined the association of tacrolimus (TAC), mycophenolate mofetil (MMF), and prednisone with BKN in renal allograft recipients transplanted between 1997 and 2004 at our center who underwent biopsies for allograft dysfunction. Drug levels or doses were recorded during the 3 months before the index biopsy. Random effects logistic modeling was used for data analysis.

RESULTS

There were 33 cases with BKN, biopsied at 16.4+/-2.8 months and 66 matched controls with biopsies at 21.5+/-2.1 months posttransplant (P=0.16). After adjusting for sex, race, retransplant status, diabetes, donor source, and induction agent, TAC blood level was associated with increased risk of BKN (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.02-1.7, P=0.03), whereas MMF dose was not (OR 1.0, 95% CI 0.99-1.0, P=0.2). Moreover, prednisone dose was also found to be a significant risk factor for BKN (OR 1.22, 95% CI 1.04-1.4, P=0.02).

CONCLUSIONS

The results of this study show that BKN is associated with TAC level and prednisone dose and not with MMF dose. This suggests that reducing TAC and prednisone dose and maintaining MMF may be a more appropriate initial approach for the treatment of BKN. Further studies are needed to compare the efficacy and safety of this approach with the currently recommended one.

Monthly screening for polyoma virus eliminates BK nephropathy and preserves renal function

BACKGROUND

Polyoma BK virus nephropathy is a serious complication after renal transplantation and is associated with a high rate of allograft failure. Progressive infection with BK virus in immunocompromised renal transplant recipients occurs in detectable stages: Viruria, viremia, then nephropathy.

METHODS

In January, 2006, we initiated a plasma screening policy for all new transplant recipients, with monthly blood testing for BK virus by polymerase chain reaction (PCR). Between January 1, 2006, and February 28, 2007, 66 renal transplants were performed at our center. The 11 patients with a positive plasma BK PCR test underwent prompt reduction in baseline immunotherapy consisting of a 50% daily dose reduction (n = 6) or complete discontinuation of therapy with mycophenolate mofetil (n = 5).

RESULTS

After reduction or discontinuation of mycophenolate mofetil, 10 patients became negative for BK virus in the plasma within 6 months. Progression to BK nephropathy has not occurred, and renal transplant dysfunction secondary to acute cellular rejection developed in only 1 patient (9%). One year post-transplant, the mean serum creatinine values for these 11 patients remained stable at 1.5 mg/dL.

CONCLUSION

Monthly plasma screening for BK virus by PCR together with immunosuppressive regimen reduction prevents BK nephropathy. In addition, this intensive screening protocol is associated with a low rate of acute rejection and excellent preservation of renal function.

An OPTN analysis of national registry data on treatment of BK virus allograft nephropathy in the United States

INTRODUCTION

Published data for BK virus allograft nephropathy, a recently emerged graft-threatening complication of kidney transplantation, are from limited-center series. Since June 30, 2004, the Organ Procurement Transplant Network national registry in the United States started collecting data on treatment of BK virus (TBKV) on the kidney follow-up forms. This study determined the rates of TBKV within 24 months posttransplant time and elucidated the risk factors for TBKV from this multicenter database.

METHODS

We queried the database for all primary and solitary kidney transplant recipients transplanted between January 1, 2003 and December 31, 2006, followed through July 18, 2008, and who were reported to have TBKV. Cumulative incidence of TBKV over time was estimated using Kaplan-Meier (K-M) method to reduce potential under reporting. A Cox proportional hazards regression model was fitted to determine risk factors for TBKV development, and time dependent Cox model was fitted to determine if TBKV was associated with higher risk of graft loss.

RESULTS

We included 48,292 primary and solitary kidney transplants from the US Organ Procurement Transplant Network database. The cumulative K-M incidence of BKVAN kept rising over time (0.70% at 6 months posttransplant to 2.18% at 1 year, 3.45% at 2 years and 6.6% at 5 years). Risk for BKVAN was higher with certain immunosuppressive regimens that included rabbit antithymocyte globulin or tacrolimus/mycophenolate combinations. Higher center volume and living kidney donation exerted a protective effect. Of concern, TBKV rates were significantly higher in more recent transplant years. TBKV report was associated with higher risk of subsequent graft loss (adjusted hazard ratio=1.69, P<0.001).

Identification of species-specific and cross-reactive epitopes in human polyomavirus capsids using monoclonal antibodies

The human antibody response to polyomavirus capsid proteins is not well characterized. Recombinant BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40) virus-like particles (VLP) were produced in a baculovirus system, and mouse monoclonal antibodies (mAbs) to these proteins were generated using standard methods. Nine of 12 BKV mAbs showed neutralizing activity. The non-neutralizing antibodies also bound BKV pseudocapsids in an ELISA binding assay. Most antibodies recognized conformational species-specific epitopes, but several exceptions were found: (i) BKV mAb BK-F11 cross-reacted with a linear buried epitope common to both JCV and SV40 pseudocapsids, (ii) two of six JCV antibodies (JC-6.7 and JC-7.9) and two of 13 SV40 antibodies (VP1-H2 and VP1-I2) recognized linear buried epitopes common to all three viruses and (iii) SV40 antibody VP1-E5 recognized a linear surface epitope on JCV pseudocapsids.

Prospective monitoring of BK virus replication in renal transplant recipients

BACKGROUND

BK virus-associated nephropathy (BKVAN) can be diagnosed only with renal graft biopsy. Definitive diagnosis of BKVAN requires demonstration of BK virus (BKV) replication in renal allograft tissues. Non-invasive analysis of urine and blood is considered essential in screening renal transplant recipients.

PATIENTS AND METHODS

This study evaluated prospectively the replication of BKV in plasma and urine with qualitative and quantitative real-time polymerase chain reaction in 32 de novo (group A) and 34 chronic (group B) renal transplant recipients and the long-term impact on graft function.

RESULTS

In group A, 456 samples (228 plasma, 228 urine) were examined and BKV was detected in 31 (31/228, 14%) samples of plasma and 57 (57/228, 25%) samples of urine in 20 (20/32, 62.5%) and 23 (23/32, 72%) recipients, respectively. Incidence of viremia and viruria increased during the first 6 months presenting a peak the third postoperative month (viremia: 28% and viruria: 31%). Immune suppressive treatment with tacrolimus showed significant relation with viremia. Renal graft function in de novo renal transplant recipients remained stable throughout the follow-up period without influence of BKV replication. In group B, incidence of viremia and viruria were 3% (1/34) and 9% (3/34) correspondingly, indicating that after the first post-transplant year the risk of BKV re-activation is diminished.

CONCLUSION

The highest incidence of BK viremia and viruria is observed the third post-transplantation month, confirming previously published studies in Europe and the United States, and long-term follow up shows that BKV replication decreases significantly after the third post-transplant month and even transient viremia or viruria does not have an impact on renal function.

longitudinal analysis of levels of immunoglobulins against BK virus capsid proteins in kidney transplant recipients

This study sought to evaluate serology and PCR as tools for measuring BK virus (BKV) replication. Levels of immunoglobulin G (IgG), IgM, and IgA against BKV capsids were measured at five time points for 535 serial samples from 107 patients by using a virus-like particle-based enzyme-linked immunosorbent assay. Viral DNA in urine and plasma samples was quantitated. The seroconversion rate was 87.5% (14/16); 78.6% (11/14) and 14.3% (2/14) of patients who seroconverted developed viruria and viremia, respectively. Transient seroreversion was observed in 18.7% of patients at 17.4 +/- 11.9 weeks posttransplant and was not attributable to loss of antigenic stimulation, changes in immunosuppression, or antiviral treatment. Titers for anti-BK IgG, IgA, and IgM were higher in patients with BKV replication than in those without BKV replication. A rise in the optical density (OD) of anti-BK IgA (0.19), IgM (0.04), or IgG (0.38) had a sensitivity of 76.6 to 88.0% and a specificity of 71.7 to 76.1% for detection of viruria. An anti-BK IgG- and IgA-positive phenotype at week 1 was less frequent in patients who subsequently developed viremia (14.3%) than in those who subsequently developed viruria (42.2%) (P = 0.04). Anti-BK IgG OD at week 1 showed a weak negative correlation with peak urine viral load (r = -0.25; P = 0.05). In summary, serial measurements of anti-BKV immunoglobulin class (i) detect onset of viral replication, (ii) document episodes of seroreversion, and (iii) can potentially provide prognostic information.

The prevalence of BK polyomavirus infection in outpatient kidney transplant recipients followed in a single center

BACKGROUND

BK polyomavirus (BKV) infection has emerged as an important cause of renal allograft loss. There is no proven therapy, and much basic clinical information is still lacking.

METHODS

We serially enrolled 95 outpatient renal transplant recipients (43% of whom were African American) in a single center cross-sectional screening study to determine the prevalence of BKV infection by whole blood polymerase chain reaction, and the prevalence of decoy cells by urinalysis and cytology. We also investigated the demographic and clinical factors associated with BKV infection, and the performance of urinalysis for decoy cells as a screening test for BKV infection.

RESULTS

The point prevalence of active BKV viremia was 7.4%. When subjects without active viremia but with a history of viremia and/or nephropathy were included, the overall prevalence was 15.8%. Urinary decoy cells were common, present in 50% of subjects at study entry. Urinalysis for decoy cells as a screen for BKV viremia had a sensitivity of 86%, specificity of 52%, positive predictive value of 13% and negative predictive value of 98%.

CONCLUSIONS

Decoy cells on urinalysis were the only factor independently associated with an increased risk of BKV infection on multivariate analysis. Although associated with BKV infection on univariate analysis, thymoglobulin, mycophenolate mofetil, and tacrolimus use were not independently associated with BKV infection on multivariate analysis, neither were history of acute rejection, gender, race, nor cause of end-stage renal disease.

Viral lower urinary tract infections

Lower urinary tract infections (UTIs) are common among the general population and are most often caused by bacterial pathogens. Viruses are an uncommon cause of UTIs in an immunocompetent host; however, viruses are increasingly recognized as the cause of lower UTI, especially hemorrhagic cystitis, among immunocompromised patients. BK virus, adenovirus, and cytomegalovirus are predominant pathogens involved in hemorrhagic cystitis after stem cell and solid organ transplantation, and their early diagnosis and treatment may prevent significant morbidity of hemorrhagic cystitis. The diagnosis of viral lower UTI is based on molecular techniques, and real-time polymerase chain reaction is often the method of choice because it allows for quantification of viral load. Cidofovir is becoming a drug of choice in viral UTIs because it is active against the most common viral pathogens. This review discusses the epidemiology, pitfalls in diagnosis, and current treatment of viral UTIs.

Prospective study of urine cytology screening for BK polyoma virus replication in renal transplant recipients

OBJECTIVE

BK virus (BKV) may be associated with interstitial nephritis in renal transplant recipients and this can lead to irreversible chronic allograft dysfunction. Early diagnosis of BKV nephropathy determines its progress because no specific antiviral therapy exists. Urine cytology, detection of viral DNA in urine or blood and renal biopsy are the main diagnostic tools. The purpose of this study was to evaluate the use of urine cytology for diagnosis of BKV replication in renal graft recipients.

PATIENTS AND METHODS

We studied 32 de novo renal transplant recipients prospectively with sequential urine samples for a period of 1 year. Thin-Prep methodology was used to prepare the slides. Cytology results were correlated with polymerase chain reaction (PCR) in urine and blood.

RESULTS

Decoy cells indicative of BKV infection were detected in 14 (7.3%) of the 190 urine samples derived from 11 recipients. In three cases with positive decoy cells, BK viraemia and viruria were simultaneously identified. In a further three cases, BKV active replication was confirmed in urine by both cytology and PCR.

CONCLUSIONS

Urine cytology is an easy and rapid method of detecting decoy cells in cases where renal biopsy is not possible. However, the low incidence of detection of decoy cells in the present study, together with poor correlation with PCR results, questions its sensitivity and specificity in diagnosing BKV reactivation.

BK polyoma virus nephropathy among Iranian renal transplant recipients

BACKGROUND

BK virus nephropathy (BKVN) is recognized as a cause of graft loss in renal transplant patients. The disorder may be related to the introduction of new, potent immunosuppressive regimens. We sought to assess the prevalence, outcome, and clinical characteristics of BKVN.

MATERIALS AND METHODS

We retrospectively analyzed 160 specimens from episode biopsies. BKVN was diagnosed by light microscopic examination and positive immunohistochemical staining.

RESULTS

Among 160 patients, 21 (13.1%) were diagnosed as BKVN. The mean interval between biopsy and transplantation was 13.6 +/- 10.67 months. There were no significant differences between BKVN patients and non-BKVN patients with respect to age, sex, interval between diagnosis and transplantation, cyclosporine blood level, and azathioprine versus mycophenolate mofetil immunosuppression. Graft loss occurred in 57.1% of BKVN versus 12.2% of non-BKVN subjects (P = .005). There was a significant difference between antilymphocyte globulin (ALG)- and non-ALG-treated groups with respect to the incidence of BKVN (6.6% in non-ALG versus 19% in ALG groups; P < .01). BKVN was diagnosed by immunohistochemistry in 61% of specimens with acute rejection according to light microscopic evaluation.

CONCLUSIONS

This is the first report of BKVN in Iranian renal allograft recipients. In our hospital, the prevalence of BKVN was higher than that previously reported for non-Iranian recipients. BKVN had a negative impact on graft survival.

Viral infection after renal transplantation: surveillance and management

Viral infections remain a significant cause of morbidity and mortality following renal transplantation. Although cytomegalovirus is the most common opportunistic pathogen seen in transplant recipients, numerous other viruses have also affected outcomes. In some cases, preventive measures such as pretransplant screening, prophylactic antiviral therapy, or post transplant viral monitoring may limit the impact of these infections. Recent advances in laboratory monitoring and antiviral therapy have improved outcomes. This review will summarize the major viral infections seen following transplant and discuss strategies for prevention and management of these potential pathogens.

[Surgical treatment of ureteral stenosis after kidney transplantation]

Ureteral stenosis is the most frequent complication after kidney transplantation. The diagnosis is based on an elevated creatinine level and a dilatation of the urinary cavity. The first step of the management is a urinary diversion with endo-ureteral prosthesis or a nephrostomy placement. The surgical gold standard is the pyelo-ureterostomy. This is a safe and efficient technique in the treatment of this complication. We describe the different surgical alternatives and the endo-urologic management of the stenosis.