Progressive multifocal leukoencephalopathy in transplant recipients

Polyoma virus-associated progressive multifocal leukoencephalopathy after renal transplantation: regression following withdrawal of mycophenolate mofetil

The 2008-released FDA safety report described a potential association between use of MMF and progressive multifocal leukoencephalopathy. We here report the case of an 11-yr-old kidney transplanted boy suffering from PML who showed rapid improvement parallel to withdrawal of MMF. This case contributes to the increasing knowledge on side effects of MMF treatment in children.

From Clinical Presentation to the Outcome: the Natural History of PML in a Portuguese Population of HIV Infected Patients

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system, associated with immunosuppression states. As there are only some non-published documents concerning PML in HIV infected patients in Portugal, we pretend to characterize natural history of PML infection in a population of HIV patients.

METHODS

We retrospectively reviewed, from 1992 to 2009, PML cases in a population of 724 HIV infected patients followed in our institution. Clinical, biological, imagery features and outcomes were characterized.

RESULTS

Twenty-five (3.45%) patients were identified as having PML. The mean time between HIV and PML diagnosis was 20.4 months. PML was the presentation of HIV infection in 40% of the patients, and 92% had CD4 T cell count lower than 200/mm(3). Paresis was the most common clinical presentation. No specific characteristics were found in cerebrospinal fluid and JCV DNA was positive in 3 of 7 patients. MRI revealed characteristic findings. Combined antiretroviral therapy was started or changed in 96% of the patients. Neurological condition got worse in 12 patients. From the 14 deaths, 5 were directly attributed to PML progression. Follow-up was lost in 8 patients.

CONCLUSIONS

PML was the presentation of HIV infection in more than 1/3 of patients, frequently associated with advanced immunocompromise. MRI sensitivity to PML is high, and JCV DNA determination in CSF was not revealed to be sensible. PML diagnosis should be taken into account in HIV patients presenting any neurological symptoms, and HIV infection should be suspected when radiological findings suggest PML lesions even in previously healthy individuals.

KEYWORDS

Progressive multifocal leukoencephalopathy; JC virus; Human immunodeficiency virus; Demyelinating disease.

Polyomavirus JC-targeted T-cell therapy for progressive multiple leukoencephalopathy in a hematopoietic cell transplantation recipient

Progressive multifocal leukoencephalopathy (PML) associated with polyomavirus JC (JCV) infection has been reported to be usually fatal in allogeneic hematopoietic SCT (HSCT) recipients. We present the case of a 19-year-old HSCT patient diagnosed with JCV-associated PML after prolonged immunosuppression for severe GVHD. No short-term neurological improvement was observed after antiviral treatment and discontinuation of immunosuppressive therapy. Donor-derived JCV Ag-specific CTLs were generated in vitro after stimulation with 15-mer peptides derived from VP1 and large T viral proteins. After adoptive CTL infusion, virus-specific cytotoxic cells were shown in the peripheral blood, JCV-DNA was cleared in the cerebrospinal fluid and the patient showed remarkable improvement. Adoptive T-lymphocyte therapy with JCV-specific CTLs was feasible and had no side effects. This case suggests that adoptive transfer of JCV-targeted CTLs may contribute to restore JCV-specific immune competence and control PML in transplanted patients.

JC virus infection of the brain

Since its initial description, there have been significant changes in the epidemiology, pathogenesis, and clinical and imaging manifestations of JCV infection of brain. The most common clinical manifestation is PML. Other recently described CNS manifestations are JCE, JCVGCN, and JCM. Although AIDS is the most common predisposing factor for JCV reactivation, there is increasing incidence of brain manifestations of JCV reactivation in non-HIV settings, including different rheumatologic, hematologic, and oncologic conditions; monoclonal antibody therapy; transplant recipients; primary immunodeficiency syndromes; and even in patients without any recognizable immune deficiency. IRIS may develop secondary to restoration of immunity in HIV-positive patients with PML receiving antiretroviral therapy. This is of profound clinical significance and needs to be diagnosed promptly. Imaging plays a crucial role in the diagnosis of the disease, monitoring of treatment response, identifying disease progression, and predicting prognosis. In this article, current understanding of the epidemiology, pathogenesis, clinical presentations, and all aspects of imaging of JCV infection of the brain have been comprehensively reviewed.

Natalizumab and progressive multifocal leukoencephalopathy: what are the causal factors and can it be avoided?

Natalizumab (Tysabri) was the first monoclonal antibody approved for the treatment of relapsing forms of multiple sclerosis (MS). After its initial approval, 3 patients undergoing natalizumab therapy in combination with other immunoregulatory and immunosuppressive agents were diagnosed with progressive multifocal leukoencephalopathy (PML). The agent was later reapproved and its use restricted to monotherapy in patients with relapsing forms of MS. Since reapproval in 2006, additional cases of PML were reported in patients with MS receiving natalizumab monotherapy. Thus, there is currently no convincing evidence that natalizumab-associated PML is restricted to combination therapy with other disease-modifying or immunosuppressive agents. In addition, recent data indicate that risk of PML might increase beyond 24 months of treatment.

Progressive multifocal leukoencephalopathy and promyelocytic leukemia nuclear bodies: a review of clinical, neuropathological, and virological aspects of JC virus-induced demyelinating disease

Progressive multifocal leukoencephalopathy is a fatal viral-induced demyelinating disease that was once rare but has become more prevalent today. Over the past decades, much has been learned about the disease from molecular study of the etiological agent of the disease, JC virus. Recently, promyelocytic leukemia nuclear bodies (PML-NBs), punctuate structures for important nuclear functions in eukaryotic cells, were identified as an intranuclear target of JC virus infection. Neuropathologically, JC virus-infected glial cells display diffuse amphophilic viral inclusions by hematoxylin–eosin staining (full inclusions), a diagnostic hallmark of this disease. Recent results using immunohistochemistry, however, revealed the presence of punctate viral inclusions preferentially located along the inner nuclear periphery (dot-shaped inclusions). Dot-shaped inclusions reflect the accumulation of viral progeny at PML-NBs, which may be disrupted after viral replication. Structural changes to PML-NBs have been reported for a variety of human diseases, including cancers and neurodegenerative disorders. Thus, PML-NBs may provide clues to the further pathogenesis of JC virus-induced demyelinating disease. Here, we review what we have learned since the disease entity establishment, including a look at recent progress in understanding the relationship between JC virus, etiology and PML-NBs.

JC virus T-Antigen DNA in gastrointestinal mucosa of immunosuppressed patients: a prospective, controlled study

BACKGROUND

JC virus (JCV), a polyoma virus, is the etiological agent of progressive multifocal leukoencephalopathy in immunosuppressed patients. JCV T-Ag has proven oncogenic potential and is expressed in colonic polyps and carcinomas. We proposed that the prevalence of JCV T-Ag DNA is higher in the normal gastrointestinal (GI) mucosa of immunosuppressed patients compared with their immunocompetent counterparts.

AIMS

To look for JCV T-Ag DNA in the normal gastrointestinal mucosa of immunosuppressed patients compared with immunocompetent controls.

METHODS

Macroscopically normal samples of upper and lower GI mucosa were obtained from 38 immunosuppressed patients. A control group included samples from 19 immunocompetent inflammatory bowel disease (IBD) and 29 non-IBD cases. DNA was extracted and polymerase chain reaction (PCR) was performed using primers specific for T-Ag.

RESULTS

JCV T-Ag DNA was found in nine of the immunosuppressed patients (23.7%) and in three of the controls (6.3%; P = 0.02). Transplant recipients had a particularly high prevalence of JCV T-Ag DNA (35.3%). Patients with IBD receiving immunosuppressive drugs had a higher prevalence of JCV T-Ag DNA in comparison with IBD patients who did not receive immunosuppression (22.2% versus 10.5%, respectively), but this difference was not statistically significant (P = 0.574).

CONCLUSION

JCV T-Ag DNA is more prevalent in the upper and lower GI mucosa of immunosuppressed patients, possibly indicating that the virus resides in these patients. This may account for the higher prevalence of GI carcinomas in immunosuppressed patients.

Psychiatric issues in solid organ transplantation

The identification and treatment of psychiatric comorbidity in patients undergoing solid organ transplantation present a unique opportunity for psychiatric involvement in the care of medically complex patients. The burden of psychiatric illness in patients awaiting transplant and following transplant is significant and associated with potential morbidity and mortality. Possibilities for psychiatric liaison with our colleagues in transplant medicine and surgery start with the comprehensive psychiatric evaluation that is often performed with potential organ recipients and donors. The vital role of the psychiatrist continues following transplantation, as adjustment is often a stressful experience with associated psychiatric comorbidity. The treatment of psychiatric illness in patients following transplantation requires an understanding of the immunosuppressant medications that patients may be taking, coupled with an awareness of the associated risks of adverse effects and drug-drug interactions.

Neurologic manifestations of transplant complications

Neurologic complications affect posttransplant recovery of more than 20% of transplant recipients. Etiology is usually related to surgical procedure of transplantation, primary disorders causing failure of transplanted organ, opportunistic infections, and neurotoxicity of immunosuppressive medications. Risk of opportunistic infections and immunosuppressant neurotoxicity is greatest within the first six months, but it persists along with long-term maintenance immunosuppression required to prevent graft rejection. Neurotoxicity may require alteration of immunosuppressive regimen, and prompt therapy of opportunistic infections improves outcomes.

Unmasking of PML by HAART: unusual clinical features and the role of IRIS

For patients with HIV/AIDS, highly active antiretroviral therapy (HAART) is currently the only effective therapy for progressive multifocal leukoencephalopathy (PML), a viral-induced demyelinating disease caused by polyomavirus JC. Immune reconstitution inflammatory syndrome (IRIS) following initiation of HAART can cause paradoxical clinical deterioration in patients with established PML. Because the onset of PML follows soon after initiation of HAART in some cases (unmasking), we investigated the role IRIS plays in unmasked PML. We reviewed records of 20 PML cases seen from 1997-2006 at the UCSD HIV primary care clinic. Eight cases presented with PML symptoms within 6months of initiating HAART (referred to hereafter as unmasked PML), six patients were diagnosed with PML before initiating HAART, and six were diagnosed more than 6months after starting HAART. Patients with unmasked PML constituted 40% of our series, had relatively long survival, and commonly (50%) had lesions exclusively in the posterior fossa, a localization not previously reported with such a high prevalence. Only 3 of the 8 patients with unmasked PML had IRIS reactions as evidenced by contrast enhancement around lesions on MRI, suggesting that IRIS is not necessary for the pathogenesis of this syndrome.

Clinical vigilance for progressive multifocal leukoencephalopathy in the context of natalizumab use

Natalizumab therapy for patients with multiple sclerosis (MS) has been associated with both improved clinical outcomes and an increased incidence of progressive multifocal leukoencephalopathy (PML). We provide details of the etiology and recent history of PML as associated with immunosuppressive disease states, including MS. Furthermore, it offers clinical guidance on differentiating PML from a MS relapse and a review of the current treatment options for patients suspected of having developed the complication.

Changing trends in infectious disease in heart transplantation

BACKGROUND

During the past 25 years, advances in immunosuppression and the use of selective anti-microbial prophylaxis have progressively reduced the risk of infection after heart transplantation. This study presents a historical perspective of the changing trends of infectious disease after heart transplantation.

METHODS

Infectious complications in 4 representative eras of immunosuppression and anti-microbial prophylaxis were analyzed: (1) 38 in the pre-cyclosporine era (1978-1980), (2) 72 in the early cyclosporine era (1982-1984), where maintenance immunosuppression included high-dose cyclosporine and corticosteroid therapy; (3) 395 in the cyclosporine era (1988-1997), where maintenance immunosuppression included cyclosporine, azathioprine, and lower corticosteroid doses; and (4) 167 in the more recent era (2002-2005), where maintenance immunosuppression included cyclosporine and mycophenolate mofetil.

RESULTS

The overall incidence of infections decreased in the 4 cohorts from 3.35 episodes/patient to 2.03, 1.35, and 0.60 in the more recent cohorts (p < 0.001). Gram-positive bacteria are emerging as the predominant cause of bacterial infections (28.6%, 31.4%, 51.0%, 67.6%, p = 0.001). Cytomegalovirus infections have significantly decreased in incidence and occur later after transplantation (88 +/- 77 days, pre-cyclosporine era; 304 +/- 238 days, recent cohort; p < 0.001). Fungal infections also decreased, from an incidence of 0.29/patient in the pre-cyclosporine era to 0.08 in the most recent era. A major decrease in Pneumocystis jiroveci and Nocardia infections has also occurred.

CONCLUSIONS

The overall incidence and mortality associated with infections continues to decrease in heart transplantation and coincides with advances in immunosuppression, the use of selective anti-microbial prophylaxis, and more effective treatment regimens.

Progressive multifocal leukoencephalopathy following heightened immunosuppression after lung transplant

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the central nervous system caused by the JC virus that occurs in the setting of immunosuppression. A 38-year-old female lung transplant recipient at our institution received treatment for episodes of acute rejection with steroids, anti-thymocyte globulin and alemtuzumab, in addition to maintenance immunosuppression. She was diagnosed with PML 13 months after the last episode of rejection, for which she had received alemtuzumab. Despite attempted treatment with cidofovir followed by mirtazapine, PML progressed, and she ultimately died of an acute pulmonary infection and respiratory failure. We provide a detailed clinical and radiographic description of PML in a lung transplant patient and highlight its potential relationship to intensive immunosuppression, as the disease developed in the setting of markedly reduced CD4 counts.

Monoclonal antibody-associated progressive multifocal leucoencephalopathy in patients treated with rituximab, natalizumab, and efalizumab: a Review from the Research on Adverse Drug Events and Reports (RADAR) Project

Progressive multifocal leucoencephalopathy (PML) is a serious and usually fatal CNS infection caused by JC polyoma virus. CD4+ and CD8+ T lymphopenia, resulting from HIV infection, chemotherapy, or immunosuppressive therapy, are the primary risk factors. The immune modulatory monoclonal antibodies rituximab, natalizumab, and efalizumab have received regulatory approval in the USA and Europe for treatment of non-Hodgkin lymphoma, rheumatoid arthritis, and chronic lymphocytic leukaemia (Europe only); multiple sclerosis and Crohn's disease; and psoriasis, respectively. Efalizumab and natalizumab administration is associated with CD4+ T lymphopenia and altered trafficking of T lymphocytes into the CNS, and rituximab leads to prolonged B-lymphocyte depletion. Unexpected cases of PML developing in people who receive these drugs have been reported, with many of the affected individuals dying from this disease. Herein, we review clinical findings, pathology, epidemiology, basic science, and risk-management issues associated with PML infection developing after treatment with these monoclonal antibodies.

Polyomavirus infection and its impact on renal function and long-term outcomes after lung transplantation

BACKGROUND

Polyomavirus infection causes nephropathy after kidney transplantation but has not been thoroughly investigated in nonrenal organ transplantation.

METHODS

Ninety lung transplant recipients were enrolled, and they provided urine samples for over 4.5 years. Samples were analyzed for BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40) by conventional and quantitative real-time polymerase chain reaction.

RESULTS

Fifty-nine (66%) patients had polyomavirus detected at least once, including 38 patients (42%) for BKV, 25 patients (28%) for JCV, and six patients (7%) for SV40. Frequency of virus shedding in serial urine samples by patients positive at least once varied significantly among viruses: JCV, 64%; BKV, 48%; and SV40, 14%. Urinary viral loads for BKV (10 copies/mL) and JCV (10 copies/mL) were higher than for SV40 (10 copies/mL; P=0.001 and 0.0003, respectively). Polyomavirus infection was associated with a pretransplant diagnosis of chronic obstructive pulmonary disease (odds ratio 6.0; P=0.016) but was less common in patients with a history of acute rejection (odds ratio 0.28; P=0.016). SV40 infection was associated with sirolimus-based immunosuppression (P=0.037). Reduced survival was noted for patients with BKV infection (P=0.03). Patients with polyomavirus infection did not have worse renal function than those without infection, but in patients with BKV infection, creatinine clearances were lower at times when viral shedding was detected (P=0.038).

CONCLUSIONS

BKV and JCV were commonly detected in the urine of lung transplant recipients; SV40 was found at low frequency. No definite impact of polyomavirus infection on renal function was documented. BKV infection was associated with poorer survival.

Emerging viral infections of the central nervous system: part 2

The first part of this review ended with a discussion of new niches for known viruses as illustrated by viral central nervous system (CNS) disease associated with organ transplant and the syndrome of human herpesvirus 6-associated posttransplant acute limbic encephalitis. In this part, we begin with a continuation of this theme, reviewing the association of JC virus-associated progressive multifocal leukoencephalopathy (PML) with novel immunomodulatory agents. This part then continues with emerging viral infections associated with importation of infected animals (monkeypox virus), then spread of vectors and enhanced vector competence (chikungunya virus [CHIK]), and novel viruses causing CNS infections including Nipah and Hendra viruses and bat lyssaviruses (BLV).

Progressive multifocal leukoencephalopathy, a review and an extended report of five patients with different immune compromised states

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the brain caused by the JC-virus. Both a decreased cellular or humoral immune response can increase the susceptibility for JC-virus induced PML. Not only HIV infected people are at risk, a wide range of otherwise immune compromised patients are a potential target for this virus. This report of five PML patients shows the importance of a clinician's familiarity with this disease and it's presenting symptoms. The presenting symptoms of PML can sometimes mimic worsening of the underlying disease. Although different therapeutic strategies have been tried, the outcomes remain very poor. In this series, treatment with cidofovir appears not to be effective in treating PML, neither in HIV positive nor HIV negative patients. Experimental therapy with leflunomide, after tapering of the immunosuppressive medication, did change the natural course of PML in one patient.

Effect of plasma exchange in accelerating natalizumab clearance and restoring leukocyte function

BACKGROUND

Accelerating the clearance of therapeutic monoclonal antibodies (mAbs) from the body may be useful to address uncommon but serious complications from treatment, such as progressive multifocal leukoencephalopathy (PML). Treatment of PML requires immune reconstitution. Plasma exchange (PLEX) may accelerate mAb clearance, restoring the function of inhibited proteins and increasing the number or function of leukocytes entering the CNS. We evaluated the efficacy of PLEX in accelerating natalizumab (a therapy for multiple sclerosis [MS] and Crohn disease) clearance and alpha4-integrin desaturation. Restoration of leukocyte transmigratory capacity was evaluated using an in vitro blood-brain barrier (ivBBB).

METHODS

Twelve patients with MS receiving natalizumab underwent three 1.5-volume PLEX sessions over 5 or 8 days. Natalizumab concentrations and alpha4-integrin saturation were assessed daily throughout PLEX and three times over the subsequent 2 weeks, comparing results with the same patients the previous month. Peripheral blood mononuclear cell (PBMC) migration (induced by the chemokine CCL2) across an ivBBB was assessed in a subset of six patients with and without PLEX.

RESULTS

Serum natalizumab concentrations were reduced by a mean of 92% from baseline to 1 week after three PLEX sessions (p < 0.001). Although average alpha4-integrin saturation was not reduced after PLEX, it was reduced to less than 50% when natalizumab concentrations were below 1 mug/mL. PBMC transmigratory capacity increased 2.2-fold after PLEX (p < 0.006).

CONCLUSIONS

Plasma exchange (PLEX) accelerated clearance of natalizumab, and at natalizumab concentrations below 1 mug/mL, desaturation of alpha4-integrin was observed. Also, CCL2-induced leukocyte transmigration across an in vitro blood-brain barrier was increased after PLEX. Therefore, PLEX may be effective in restoring immune effector function in natalizumab-treated patients.

Natalizumab in the treatment of multiple sclerosis

Natalizumab reduced the rate of clinical relapse at one year by 68% and the risk of sustained progression of disability by 42-54% over 2 years in its pivotal phase III trial (AFFIRM) in relapsing-remitting multiple sclerosis (RRMS). Natalizumab is generally well tolerated, but due to rare and potentially fatal side-effects, it was approved with a restricted-distribution format in 2006. Expert statements and the European Medical Agency recommend the use of natalizumab after failure of first-line disease-modifying therapies in patients with relapsing forms of MS. As part of the risk management plan, worldwide extensive safety programmes aim to provide more data on natalizumab safety in clinical practice. At the end of September 2008, 48 000 patients have received natalizumab and 18000 patients are on treatment for at least 1 year. The assessment of risk and benefit is still ongoing.

JC virus: an oncogenic virus in animals and humans?

JC virus (JCV) is a human polyomavirus of the Polyomaviridae family, which also includes BK virus and simian vacuolating virus 40 (SV40). JC virus was first isolated in 1971 from the brain of a patient with Progressive Multifocal Leukoencephalopathy (PML). Like other polyomaviruses, JCV has a restricted host range. The virus infects the majority of the human population with seroconversion occurring during adolescence. JCV has a limited and specific tissue tropism infecting the kidney and oligodendrocytes and astrocytes in the central nervous system (CNS). Initial JCV infection is generally asymptomatic in immunocompetent hosts, and it establishes a persistent infection in the kidney and possibly bone marrow. In immunocompromised individuals JCV can cause a lytic infection in the CNS and lead to development of the fatal, demyelinating disease PML. The name polyoma is derived from the Greek terms: poly, meaning many, and oma, meaning tumors, owing to the capacity of this group of viruses to cause tumors. JCV inoculation of small animal models and non-human primates, which are not permissive to a productive JCV infection, leads to tumor formation. Given the ubiquitous nature of the virus and its strong association with cancer in animal models, it is hypothesized that JCV plays a role in human cancers. However, the role for JCV in human cancers and tumor formation is not clear. Some researchers have reported an association of JCV with human cancers including brain tumors, colorectal cancers, and cancers of the gastrointestinal tract, while other groups report no correlation. Here, we review the role of JCV in cancers in animal models and present the findings on JCV in human cancers.

Infectious agents and colorectal cancer: a review of Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus

Based on the high volume of bacteria and viruses that the intestine is exposed to and the importance of infectious agents in some gastrointestinal and anogenital cancers, it is not surprising the many studies have evaluated the association between colorectal cancer and infectious agents. This review highlights investigations of four agents in relation to colorectal cancer. Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus have all been evaluated as possible etiologic agents for colorectal cancer. For each of these agents, a review of possible mechanisms for carcinogenesis and epidemiologic evidence is discussed, and future directions for research are proposed.

An update on the use of mycophenolate mofetil in lupus nephritis and other primary glomerular diseases

Mycophenolate mofetil (MMF) has been used successfully as an immunosuppressive medication in transplantation for over a decade. Owing to its efficacy and relatively benign adverse effect profile, its use has been investigated in the treatment of several glomerular diseases, as we describe in this Review. Of these, MMF has most extensively been studied in lupus nephritis. Randomized controlled trials have documented the value of MMF in both induction and maintenance therapy for severe lupus nephritis in several different geographic and ethnic populations, and have defined its potential toxicity. In minimal-change disease, focal segmental glomerulosclerosis and membranous nephropathy, promising but limited data on MMF treatment exist from small retrospective and prospective studies. Ongoing, larger, prospective trials, such as the NIH trial in focal segmental glomerulosclerosis, might clarify the value of MMF in the treatment of this disease. The efficacy of MMF in IgA nephropathy remains unclear, despite several small, controlled trials. Conflicting results might reflect differences in the disease process, differences in MMF metabolism, or varying responses to the immunosuppressive agent in different populations. Only through large, collaborative, controlled trials will the true role of MMF be defined for each glomerular disease.

Update on PML: lessons from the HIV uninfected and new insights in pathogenesis and treatment

Significant advances in our understanding of progressive multifocal leukoencephalopathy (PML) and its causative agent, JC virus, have been made since PML was first described 50 years ago. However, immune reconstitution remains the only proven, effective therapy in this devastating central nervous system disorder. Early diagnosis and adjustments of immune suppressants and modulator agents are critical in managing PML in HIV-negative patients. This review summarizes recent advances in our understanding of PML in HIV-uninfected patients in oncology, rheumatology, organ transplantation, and idiopathic immune deficiency and in association with novel therapeutics. Brain MRI data from our case series of brain biopsy-proven HIV-negative PML patients indicate the presence of an inflammatory/immune reaction in brain tissues, which was confirmed by immunocytologic analysis. Future studies to better understand PML pathogenesis in HIV-negative individuals may help uncover new potential therapeutic targets and improve PML outcomes.

THE SURGICAL MANAGEMENT OF INFECTIONS INVOLVING THE CEREBRUM

OBJECTIVE

Infection involving the cerebrum is a true neurosurgical emergency that requires rapid diagnosis and appropriate surgical and medical intervention to achieve good clinical outcome.

METHODS

Because of the potential for devastating neurological sequelae, it is imperative that neurosurgeons be involved in the diagnosis and management of these serious conditions once an infection is suspected. With the advent of computed tomography and magnetic resonance imaging, it is now possible to detect an infectious process early in its course and follow the response to therapy. Although significantly more effective than in the past, antimicrobial therapy alone is insufficient to eradicate most intracranial infections, especially in the presence of compression or displacement of the cerebrum. Surgery remains an essential part of the management of intracranial infection because of its ability to provide immediate relief from pressure on neural structures and thereby result in clinical improvement.

RESULTS

The most common infections affecting the brain, namely, cranial epidural abscess, subdural empyema, brain abscess, viral infection, tuberculosis, and neurocysticercosis, can each be associated with significant mass effect on the cerebrum that is greatly reduced through surgery. This relief, in combination with newer antimicrobial agents that have an improved ability to cross the blood brain barrier, has led to a reduction in the infection-related morbidity and mortality rates associated with intracranial infections.

CONCLUSION

Combining advanced imaging and surgical techniques in the form of intraoperative magnetic resonance image-guided neurosurgery may further enhance clinical outcomes in these once uniformly fatal diseases.

Neuroimaging and neurologic complications after organ transplantation

Neurologic complications are common after transplantation and affect 30-60% of transplant recipients. The etiology of most of the posttransplant neurologic disorders is related to the opportunistic infections, both systemic and involving central nervous system (CNS), toxicity of immunosuppressive medications, and the metabolic insult created by the underlying primary disease and the transplant procedure. Neuroimaging studies are one of the key tools in the evaluation and enable early diagnosis of neurologic complications in transplant patients, especially posterior reversible leukoencephalopathy syndrome, central pontine myelinolysis, intracerebral hemorrhage, and fungal and bacterial abscesses. Magnetic resonance imaging (MRI) is the preferred technique, but each of the available neuroimaging techniques offers a unique insight into the pathophysiologic mechanisms underlying neurologic complications of transplantation. The role of neuroimaging in this population includes early detection of calcineurin inhibitor neurotoxicity, opportunistic infections, neoplasia, metabolic disorders, or cerebrovascular diseases. In addition, we can monitor longitudinal progression of disease and treatment response.

[Progressive multifocal leukoencephalopathy in a non-AIDS patient: high efficiency of combined cytarabine and cidofovir]

INTRODUCTION

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system, occurring in immunocompromised patients. Treatment, not codified to date, is more often inefficient with a rapid and fatal deterioration.

CASE RECORD

A 48-year-old woman, treated with immunosuppressant agents for systemic lupus, presented with PML mimicking neurolupus flare. A complete remission was obtained with cytarabine and cidofovir.

CONCLUSION

Combined cytarabine and cidofovir appears a promising therapeutic option in PML associated with autoimmune systemic disorders.

Natalizumab treatment for multiple sclerosis: recommendations for patient selection and monitoring

Natalizumab is a new treatment option for patients with active relapsing-remitting multiple sclerosis. In phase III studies, natalizumab was highly effective and well tolerated; however, three cases of progressive multifocal leucoencephalopathy (PML) were identified (estimated incidence of one per 1000; 95% CI 0.2-2.8; mean treatment period 17.9 months). In this Review we summarise the current information on PML, the three confirmed cases of PML, and the results of an extensive safety assessment of all patients treated with natalizumab. On the basis of these reviews, we make recommendations for appropriate selection of candidates for natalizumab and pretreatment assessments. In addition, a three-step diagnostic and management algorithm was developed to monitor natalizumab-treated patients with multiple sclerosis for PML and other opportunistic infections. The algorithm includes strategies for clinical, MRI, and laboratory assessments. Maintaining clinical vigilance allows for early suspension of natalizumab in potential cases of PML, thereby increasing the opportunity for immune reconstitution, which may improve prognosis if PML is confirmed.

Inhibitory activities of three classes of acyclic nucleoside phosphonates against murine polyomavirus and primate simian virus 40 strains

Murine polyomavirus and simian virus 40 were used to evaluate the potencies of the compounds of three classes of acyclic nucleoside phosphonates: (i) the original HPMP (3-hydroxy-2-phosphonomethoxypropyl) and PME (2-phosphonomethoxyethyl) derivatives, (ii) the 6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidine (DAPy) derivatives, and (iii) a new class of HPMP derivatives containing a 5-azacytosine moiety. The last class showed the highest activities and selectivities against both polyomaviruses.

Fatalities in natalizumab treatment--a 'no go' for leukocyte recirculation approaches?

Natalizumab (Tysabri), Biogen Idec/Elan) is a humanised neutralising antibody directed against alpha4 integrin expressed by leukocytes. Although it is an effective therapy for multiple sclerosis (MS), the serious adverse effect of progressive multifocal leukoencephalopathy (PML) resulted in its voluntary withdrawal from the market by Biogen Idec/Elan in February 2005. This has raised debates on whether PML was caused by blocking leukocyte trafficking-mediated immune suppression or by other effects through targeting alpha4 integrin per se. The authors propose that natalizumab-associated PML is a target-specific side effect predominantly due to the combination of: i) blocking leukocyte trafficking to peripheral organs resulting in reduced immune surveillance; ii) mobilisation of PML-causative JC virus-carrying bone marrow precursor cells and splenic marginal zone B cells; and iii) migration of these cells to sites of inflammation such as the brain. Therefore, combination of these effects is, so far, specific for the target alpha4 integrin and should not occur in general when interfering with other targets involved in leukocyte trafficking.

Novel treatment options for inflammatory bowel disease: targeting alpha 4 integrin

The aetiology of inflammatory bowel disease (IBD) is complex and many aspects still remain unclear. However, significant progress has been made in understanding the pathogenesis of chronic inflammation in the intestine, and new insights have been gained recently. A better understanding of the immunopathology of IBD has led to the development of novel biological agents to target crucial molecules and processes in the inflammatory cascade. The development of novel therapies in the management of IBD has moved from empirical to scientific rational translation from bench to bedside. Lymphocyte infiltration into the intestinal tract in Crohn's disease (CD) is mediated by interaction between alpha4 integrin expressed on lymphocytes and its specific ligand mucosal vascular addressin cell adhesion molecule-1, expressed on the endothelial cells of the microvasculature in the inflamed intestinal tract. Development of monoclonal antibodies against alpha4 integrin permitted the targeting of lymphocyte trafficking into the intestine as a novel therapeutic intervention. Natalizumab, a recombinant humanised monoclonal antibody against alpha4 integrin, was effective in CD in a phase II randomised controlled trial. The highest response rate and remission rate were 71% and 44%, respectively, at 6 weeks after two infusions of natalizumab 3mg administered 4 weeks apart. Natalizumab was well tolerated in this trial. The phase III trial results are encouraging, although the primary efficacy endpoint of response at week 10 was not achieved. The maintenance of response and remission trial, ENACT (Evaluation of Natalizumab as Continuous Therapy)-2, has reported impressive efficacy in maintaining response and remission in those who responded in the initial induction of remission (ENACT-1) trial. This was associated with an improvement in quality-of-life parameters. A second humanised monoclonal antibody, MLN-02 (LDP-02), developed against alpha4beta7 has also shown evidence of efficacy in ulcerative colitis and CD. Although the clinical trials showed that inhibition of alpha4 integrin was well tolerated, use of natalizumab in multiple sclerosis and CD has raised serious concerns about the association with progressive multifocal leukoencephalopathy (PML) in a small number of patients, and the drug has been withdrawn from the market pending further safety evaluation. PML is caused by polyoma JC virus infection, is progressive and generally fatal, and is recognised to occur in patients with severe immunosuppression. Initial safety evaluation suggests that PML is very rare, despite its occurrence in one patient with CD receiving open-label natalizumab treatment.

Molecular and clinical perspectives of polyomaviruses: emerging evidence of importance in non-kidney transplant populations

JC virus (JCV), BK virus (BKV) and simian virus 40 (SV40) are deoxyribonucleic acid (DNA) viruses, members of the family Polyomaviridae. These viruses establish persistent infections, and reactivate from latency in their host under immunosuppression. During the last few years there has been recognition of the morbidity related to polyomaviruses, particularly BKV in kidney transplant recipients. More importantly, recent studies indicate the potential implication of JCV, BKV, and SV40 in renal dysfunction among nonrenal organ transplant patients. Polyomaviruses are tumor-inducing viruses and animal models have provided evidence of the oncogenicity of these pathogens. Although data are not conclusive, molecular studies suggest an association of BKV and SV40 with malignancies among solid organ transplant patients. As new and potent immunosuppressive agents are introduced into clinical practice, it is believed that the incidence of polyomavirus-related diseases in organ transplantation might increase. This review evaluates the biologic and epidemiologic features of these 3 viruses, the data regarding their infections in nonkidney organ transplant patients and describes future directions in the management and research of these opportunistic pathogens.

[Progressive multifocal leukoencephalopathy secondary to JC virus infection after liver transplantation and treatment of recurrent hepatitis C]

Progressive multifocal leucoencephalopathy due to JC virus is a rare complication of liver transplantation. Only four cases have already been described in the literature. This disease is difficult to differentiate from leucoencephalopathy associated with immunosuppressive drugs such as cyclosporin or tacrolimus. Positive diagnosis of progressive multifocal leucoencephalopathy no longer requires cerebral biopsy. It must be confirmed by positive JC virus RNA amplification in the cerebrospinal fluid. We report a case of progressive multifocal leucoencephalopathy occurring 18 months after liver transplantation for hepatitis C-related cirrhosis.

JC virus chromogenic in situ hybridization in brain biopsies from patients with and without PML

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by the JC polyoma virus. Electron microscopy and immunohistochemistry are the traditional methods of confirming the presence of the virus in brain biopsies from these patients. We studied the brain biopsies from 7 patients with PML and 6 patients without PML with chromogenic in situ hybridization (CISH) for the JC polyoma virus using a commercially available probe. The biopsies from the patients with the PML cases were proven to contain the JC polyoma virus by traditional and molecular methods. The CISH findings were compared with the known state of infection. All (7/7) of the biopsies from patients with PML were positive for the presence of polyoma virus by CISH, whereas the biopsies from patients without PML were uniformly negative. CISH seems to be a useful tool for the detection of the JC virus in brain biopsies from patients with PML, and is more accessible because a commercial probe is available.

[New trends in progressive multifocal leukoencephalopathy]

Infection by Polyomavirus JC is a model of chronic active viral infection, closely controlled by the immune system. Progressive multifocal leucoencephalopathy (PML) is a deadly demyelinating disease of the central nervous system, consecutive to the lytic infection of oligodendrocytes by JC virus. Reactivation of JC virus occurs only in the setting of severe cellular immune deficiency. During the last 25 years, the incidence of PML has significantly increased related to the AIDS pandemic and, more recently, to the growing use of immunosuppressive drugs. There is no specific antiviral treatment for PML. Nevertheless, the availability of highly active antiretroviral therapy has changed the clinical course of PML in HIV-infected individuals. One-year mortality has decreased from 90 percent to approximately 50 percent as a result of reconstitution of the immune system. Recent advances in JC virus biology give new perspectives to the pathogenesis of PML. New trends in the understanding of the cellular immune response against the JC virus have direct implications for patient management and may lead to develop future strategy of immunotherapies for PML.

Progressive multifocal leukoencephalopathy after natalizumab therapy for Crohn's disease

The prior diagnosis of fatal astrocytoma in a 60-year-old man with Crohn's disease treated with natalizumab, a monoclonal antibody against alpha4 integrins, was reclassified as JC virus-related progressive multifocal leukoencephalopathy (PML). Analysis of frozen serum samples showed that JC virus DNA had appeared in the serum three months after the initiation of open-label natalizumab monotherapy and two months before the appearance of symptomatic PML. There was staining of the brain lesion for polyomavirus. This case report, along with two others, suggests that anti-alpha4-integrin therapy can result in JC virus-induced PML.