Pharmacotherapeutic options for the management of human polyomaviruses

Fluoroquinolones and BK Virus Nephropathy: A Myth or a Reality

BK polyomavirus (BKV) is a challenging problem for the transplant nephrologist. Various strategies have been used to prevent or treat BK virus nephropathy (BKVN). These include reduction in immunosuppression, intravenous immune globulin, cidofovir, leflunomide, and the fluoroquinolone antibiotics. All these agents have their own toxicities. Great interest was shown to use fluoroquinolones to prevent BKVN after its useful experience was reported in bone marrow transplant. Fluoroquinolones being cheap and easily available, attracted nephrologists to use it, for prevention of BKVN. These agents have been shown in vitro studies to be effective. However, there are mixed results about their effectiveness in prevention of BKVN in clinical setting. This review will focus the evidence available for using fluoroquinolones in prevention of BKVN and its usefulness. Furthermore, a way forward to use these agents or not for prevention of BKVN will also be discussed.

Impact of HMG-CoA reductase inhibitors on the incidence of polyomavirus-associated nephropathy in renal transplant recipients with human BK polyomavirus viremia

BACKGROUND

Up to 20% of renal transplant recipients (RTR) will develop human BK polyomavirus (BKPyV) viremia. BKPyV viremia is a pre-requisite of polyomavirus-associated nephropathy (PyVAN). Risk of BKPyV infections increases with immunosuppression. Currently, the only effective therapy against PyVAN is reductions in immunosuppression, but this may increase the risk of rejection. In vitro data have shown that pravastatin dramatically decreased caveolin-1 expression in human renal proximal tubular epithelial cells (HRPTEC) and suppressed BKPyV infection in these cells. Based on these data, we postulated that statin therapy may prevent the progression of BKPyV viremia to PyVAN.

PATIENTS AND METHODS

A multicenter, retrospective study was conducted in adult RTR transplanted between July 2005 and March 2012. All patients with documented BKPyV viremia (viral load >500 copies/mL on 2 consecutive tests) were included. Group I consisted of patients taking a statin before the BKPyV viremia diagnosis (n = 32), and Group II had no statin exposure before or after the BKPyV viremia diagnosis (n = 36). The primary endpoint was the incidence of PyVAN.

RESULTS

Demographic data, transplant characteristics, and the degree of immunosuppression (i.e., induction/maintenance therapies, rejection treatment) were similar between the groups, with the exception of more diabetics in Group I. The incidence of PyVAN was comparable between the 2 groups (Group I = 28.1% vs. Group II = 41.7%; P = 0.312).

CONCLUSIONS

Despite the proven in vitro effectiveness of pravastatin preventing BKPyV infection in HRPTEC, statins at doses maximized for cholesterol lowering, in RTR with BKPyV viremia, did not prevent progression to PyVAN.

Possible antiviral effect of ciprofloxacin treatment on polyomavirus BK replication and analysis of non-coding control region sequences

Acute renal dysfunction (ARD) is a common complication in renal transplant recipients. Multiple factors contribute to ARD development, including acute rejection and microbial infections. Many viral infections after kidney transplantation result from reactivation of “latent” viruses in the host or from the graft, such as the human Polyomavirus BK (BKV). We report the case of a 39 year-old recipient of a 2^nd kidney graft who experienced BKV reactivation after a second episode of acute humoral rejection. A 10-day treatment with the quinolone antibiotic ciprofloxacin was administered with an increase of immunosuppressive therapy despite the active BKV replication. Real Time PCR analysis performed after treatment with ciprofloxacin, unexpectedly showed clearance of BK viremia and regression of BK viruria. During the follow-up, BK viremia persisted undetectable while viruria decreased further and disappeared after 3 months.

BKV non-coding control region sequence analysis from all positive samples always showed the presence of archetypal sequences, with two single-nucleotide substitutions and one nucleotide deletion that, interestingly, were all representative of the subtype/subgroup I/b-1 we identified by the viral protein 1 sequencing analysis.

We report the potential effect of the quinolone antibiotic ciprofloxacin in the decrease of the BKV load in both blood and urine.

Drug-induced PML: a global agenda for a global challenge

The occurrence of severe adverse events such as progressive multifocal leukoencephalopathy (PML) has the potential to limit the benefits of highly efficacious medicines being developed to fulfill unmet clinical needs across therapeutic areas. Following an Expert meeting in London in July 2011 (http://www.ema.europa.eu/docs/en_GB/document_library/Report/2011/09/WC500111562.pdf), a research agenda, highlighting methodological, clinical, and communication elements, to mitigate the risk and improve the management of drug-induced PML has been agreed upon.

Evaluation of fluoroquinolones for the prevention of BK viremia after renal transplantation

BACKGROUND AND OBJECTIVES

Nearly 30% of renal transplant recipients develops BK viremia, a prerequisite for BK nephropathy. Case reports have evaluated treatment options for BK virus, but no controlled studies have assessed prophylactic therapies. Fluoroquinolone antibiotics were studied for prevention of BK viremia after renal transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective analysis evaluated adult renal transplant recipients with at least one BK viral load (blood) between 90 and 400 days after transplantation. Six to 12 months of co-trimoxazole was used for Pneumocystis prophylaxis. In sulfa-allergic/-intolerant patients, 6 to 12 months of atovaquone with 1 month of a fluoroquinolone was used. Fluoroquinolones can inhibit BK DNA topoisomerase. The two groups studied were those that received 30 days of levofloxacin or ciprofloxacin after transplantation and those that did not. The primary endpoint was BK viremia rates at 1 year. Of note, of the 160 patients not receiving fluoroquinolone prophylaxis, 40 received a fluoroquinolone for treatment of a bacterial infection within 3 months after transplantation. Subgroup analysis evaluating these 40 patients against the 120 who had no exposure to fluoroquinolones was completed.

RESULTS

A 1-month fluoroquinolone course after transplantation was associated with significantly lower rates of BK viremia at 1 year compared with those with no fluoroquinolone. In the subgroup analysis, exposure to fluoroquinolone for treatment of bacterial infections within 3 months after transplantation was associated with significantly lower 1-year rates of BK viremia.

CONCLUSIONS

This analysis demonstrates that fluoroquinolones are effective at preventing BK viremia after renal transplantation.

[Progressive multifocal leukoencephalopathy. Undesirable side effect of immunotherapy]

As new cases arise of progressive multifocal leukoencephalopathy (PML) in patients with multiple sclerosis (MS) treated with the monoclonal antibody natalizumab, a critical discussion about risks and advantages of this specific kind of immunotherapy appears necessary. Practical consequences and treatment options are addressed based on current concepts of PML's pathogenesis in patients treated with natalizumab. Critical patient selection based on risk:benefit considerations, limited therapy regimens, early diagnosis of PML by clinical and paraclinical criteria, and therapeutic perspectives for treating PML are discussed. The risk of PML in patients with MS needs to be continually monitored and should be reduced with all means available to ensure optimal outcome.

The role of polyomaviruses in human disease

The human polyomaviruses, BK virus and JC virus, have long been associated with serious diseases including polyomavirus nephropathy and progressive multifocal leukoencephalopathy. Both viruses establish ubiquitous, persistent infections in healthy individuals. Reactivation can occur when the immune system is impaired, leading to disease progression. Recently, the human polyomavirus family has expanded with the identification of three new viruses (KI, WU and Merkel cell polyomavirus), all of which may prove to be involved in human disease. This review describes the general aspects of human polyomavirus infections and pathogenicity. Current topics of investigation and future directions in the field are also discussed.

Repression of BK virus infection of human renal proximal tubular epithelial cells by pravastatin

BACKGROUND

BK virus (BKV), a human polyomavirus, causes BKV nephritis, which often leads to graft loss after renal transplantation. Currently, the only efficient therapy against BKV nephritis seems to be a reduction or change of immunosuppressive agents, but this may increase the inherent risk of rejection. Here, we report the ability of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor (statin), which is routinely used to treat hypercholesterolemia, to repress BKV entry pathways in human renal proximal tubular epithelial cells (HRPTEC) and, correspondently, prevent BKV infection.

METHODS

HRPTEC were co-incubated with BKV and pravastatin. Then the percentage of HRPTEC infected with BKV by immunofluorescent analysis and large T-antigen expression which suggested BKV infection by Western blots was assessed in the absence and presence of pravastatin. The distribution of purified and labeled BKV particles in the presence and absence of pravastatin was also investigated.

RESULTS

Both the percentage of BKV infected cells and the large T-antigen expression were significantly decreased in HRPTEC pretreated and co-incubated with pravastatin. However, when pravastatin was added 72 hr after BKV infection it failed to decrease percentage of BKV infected cells. It is likely, that pravastatin's inhibitory effect is explained by depletion of caveolin-1, a critical element of caveolae. BKV enters HRPTEC by caveolar-mediated endocytosis. We provide evidence that pravastatin dramatically decreased caveolin-1 expression in HRPTEC and interfered with internalization of labeled BKV particles.

CONCLUSIONS

Our data suggest that pravastatin, acting through depletion of caveolin-1, prevented caveolar-dependent BKV internalization and repressed BKV infection of HRPTEC.

Prevention and management of BK-virus associated haemorrhagic cystitis in children following haematopoietic stem cell transplantation--a systematic review and evidence-based guidance for clinical management

Haemorrhagic cystitis (HC) is a common and, in its severe form, potentially life-threatening complication of Haematopoietic stem cell transplantation (HSCT) in children. Recent data indicate an important role of BK virus reactivation during the time of maximal post-transplant immune suppression in the pathogenesis of late-onset HC. Treatment of HC is mainly symptomatic and often frustrating. To give clinicians guidance on prevention and treatment options and their backing by scientific evidence, we have systematically assessed the available literature and devised evidence-based guidelines. Our comprehensive review demonstrates that evidence for the most commonly used interventions (such as cidofovir, oestrogen, hyperbaric oxygen, bladder instillation with formalin, alum salts or prostaglandin) is very limited. Some of these interventions also carry significant risks. Higher level evidence exists only for 2-mercaptoethane sodium (MESNA) and hyperhydration as a preventative intervention, and for systemic recombinant Factor VII as a treatment to stop acute haemorrhage. Further high-quality studies are required to establish effective and safe prevention and treatment options for HC.