Progressive multifocal leukoencephalopathy in a patient with Franklin disease and hypogammaglobulinemia

Progressive multifocal leukoencephalopathy in a patient with occult hypogammaglobulinemia experiencing bilateral visual impairment

INTRODUCTION

Progressive multifocal leukoencephalopathy (PML) is a rare, lethal, demyelinating disease classically seen in profoundly immunosuppressed individuals. It is caused by intracerebral infection by John Cunningham polyomavirus (JCV). We report a rare case of PML in a man with presumed immunocompetence at presentation experiencing bilateral painless visual impairment.

CASE DESCRIPTION

A 60-year-old man with a 3-week history of bilateral painless visual impairment attended our ophthalmology department. Unusually, he navigated around the room well and was able to read 4 of 13 Ishihara test plates in spite of a best-corrected visual acuity of counting fingers at 1 m bilaterally. Slit lamp examination, routine blood tests and optical coherence tomography (OCT) of the maculae and discs were unremarkable. Diffuse hyperintense white matter lesions on T2-weighted magnetic resonance imaging of the brain and detection of JCV within the parietal lobe tissue obtained by biopsy confirmed PML. Additional investigations identified an underlying hypogammaglobulinaemia, which may have initiated PML. He received intravenous immunoglobulin but passed away 2 months after diagnosis.

CONCLUSIONS

To our knowledge this case is one of only a handful worldwide to describe PML developing in a patient with presumed immunocompetence at presentation - there was no previous history of recurrent, chronic, or atypical infections. There has only been one other report of visual symptoms presenting as the primary complaint. The case illustrates the importance of ruling out organic, central nervous system pathology in patients presenting with visual loss and normal objective visual function tests such as slit lamp examination and OCT.

The clinical utility of JC virus antibody index measurements in the context of progressive multifocal leukoencephalopathy

In natalizumab-treated patients without previous immunosuppressive treatment, the JCV antibody index is used to stratify PML risk. A high index value indicates that the risk to develop PML is significantly elevated, although probably about 99% of patients with this index value will not develop PML. This minireview aimed to provide an overview of the basic virology and immunology relevant to understanding JCV infections in MS patients, with a focus on what is presently known about antibodies to JCV and how they could be of use to predict and diagnose PML.

Progressive Multifocal Leukoencephalopathy in Primary Immune Deficiencies: Stat1 Gain of Function and Review of the Literature

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a rare, severe, otherwise fatal viral infection of the white matter of the brain caused by the polyomavirus JC virus, which typically occurs only in immunocompromised patients. One patient with dominant gain-of-function (GOF) mutation in signal transducer and activator of transcription 1 (STAT1) with chronic mucocutaneous candidiasis and PML was reported previously. We aim to identify the molecular defect in 3 patients with PML and to review the literature on PML in primary immune defects (PIDs).

METHODS

STAT1 was sequenced in 3 patients with PML. U3C cell lines were transfected with STAT1 and assays to search for STAT1 phosphorylation, transcriptional response, and target gene expression were performed.

RESULTS

We identified 3 new unrelated cases of PML in patients with GOF STAT1 mutations, including the novel STAT1 mutation, L400Q. These STAT1 mutations caused delayed STAT1 dephosphorylation and enhanced interferon-gamma-driven responses. In our review of the literature regarding PML in primary immune deficiencies we found 26 cases, only 54% of which were molecularly characterized, the remainder being syndromically diagnosed only.

CONCLUSIONS

The occurrence of PML in 4 cases of STAT1 GOF suggests that STAT1 plays a critical role in the control of JC virus in the central nervous system.

Broadly neutralizing human monoclonal JC polyomavirus VP1-specific antibodies as candidate therapeutics for progressive multifocal leukoencephalopathy

In immunocompromised individuals, JC polyomavirus (JCPyV) may mutate and gain access to the central nervous system resulting in progressive multifocal leukoencephalopathy (PML), an often fatal opportunistic infection for which no treatments are currently available. Despite recent progress, the contribution of JCPyV-specific humoral immunity to controlling asymptomatic infection throughout life and to eliminating JCPyV from the brain is poorly understood. We examined antibody responses against JCPyV major capsid protein VP1 (viral protein 1) variants in the serum and cerebrospinal fluid (CSF) of healthy donors (HDs), JCPyV-positive multiple sclerosis patients treated with the anti-VLA-4 monoclonal antibody natalizumab (NAT), and patients with NAT-associated PML. Before and during PML, CSF antibody responses against JCPyV VP1 variants show "recognition holes"; however, upon immune reconstitution, CSF antibody titers rise, then recognize PML-associated JCPyV VP1 variants, and may be involved in elimination of the virus. We therefore reasoned that the memory B cell repertoire of individuals who recovered from PML could be a source for the molecular cloning of broadly neutralizing antibodies for passive immunization. We generated a series of memory B cell-derived JCPyV VP1-specific human monoclonal antibodies from HDs and a patient with NAT-associated PML-immune reconstitution inflammatory syndrome (IRIS). These antibodies exhibited diverse binding affinity, cross-reactivity with the closely related BK polyomavirus, recognition of PML-causing VP1 variants, and JCPyV neutralization. Almost all antibodies with exquisite specificity for JCPyV, neutralizing activity, recognition of all tested JCPyV PML variants, and high affinity were derived from one patient who had recovered from PML. These antibodies are promising drug candidates for the development of a treatment of PML.

Fatal encephalitis due to BK virus in a patient with common variable immunodeficiency: a case report

Encephalitis due to BK virus is a rare condition. Here, we describe a young male patient with common variable immunodeficiency who developed fatal encephalitis due to BK virus. The patient presented initially with ocular symptoms that were followed by behavioral changes and spastic quadriparesis. Diagnosis was made by the compatible clinical findings and detection of viral DNA by polymerase chain reaction in the cerebrospinal fluid. To the best of our knowledge, this is the first report of BK virus encephalitis in a patient with common variable immunodeficiency. We suggest that BK virus should be suspected in cases of encephalitis; particularly in patients with immunodeficiency.

Progressive multifocal leukoencephalopathy: what's new?

Progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease that is caused by human JC polyomavirus, was first described as a complication of immune suppression 50 years ago and emerged as a major complication of HIV infection in the 1980s. The prognosis has remained dismal since then, with discouraging results from clinical trials of various therapeutic approaches, including immunomodulation and/or inhibition of viral replication. PML is caused by reactivation of latent JC virus, and serotonergic 5-HT(2a) receptors have been identified as being critical for viral infection of glial cells. In recent years, immunosuppressive therapeutic antibodies have been associated with an increased incidence rate of PML. Here, the authors review findings on the pathogenesis of PML and the encouraging case reports of novel treatments.