Immunological and clinical consequences of treating a patient with natalizumab

Chemokine-mediated cell migration into the central nervous system in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) has been associated with different forms of immune compromise. This study analyzes the chemokine signals and attracted immune cells in cerebrospinal fluid (CSF) during PML to define immune cell subpopulations relevant for the PML immune response. In addition to chemokines that indicate a general state of inflammation, like CCL5 and CXCL10, the CSF of PML patients specifically contains CCL2 and CCL4. Single-cell transcriptomics of CSF cells suggests an enrichment of distinct CD4+ and CD8+ T cells expressing chemokine receptors CCR2, CCR5, and CXCR3, in addition to ITGA4 and the genetic PML risk genes STXBP2 and LY9. This suggests that specific immune cell subpopulations migrate into the central nervous system to mitigate PML, and their absence might coincide with PML development. Monitoring them might hold clues for PML risk, and boosting their recruitment or function before therapeutic immune reconstitution might improve its risk-benefit ratio.

Learning CNS immunopathology from therapeutic interventions

Modulation of immune cell trafficking across the blood-brain barrier has not only introduced a therapeutic avenue for multiple sclerosis (MS) but also represents an example of reverse translational medicine. Data from clinical trials of drugs such as natalizumab and fingolimod have revealed the involvement of different compartments in relapsing versus non-relapsing MS immune biology, contributed to our understanding of central nervous system (CNS) immune surveillance, and stimulated new fields of research. Here, we discuss the results of these trials, as well as patient biomaterial-based scientific projects, and how both have informed our understanding of CNS immunopathology.

[Differential diagnosis of immune reconstitution inflammatory syndrome and progressive multifocal leukoencephalopathy after natalizumab withdrawal]

The appearance of new foci on MRI, the increase in neurological deficits, including the appearance of cognitive disorders and disturbances in the level of consciousness in patients with multiple sclerosis during the «washing period» when transferring from natalizumab (NZ) to another drug, may be due to both progressive multifocal leukoencephalopathy (PML) and exacerbation of the disease in the absence of therapy. Discontinuation of NS is fraught not only with a resumption, but with an increase in disease activity, the development of an immune reconstitution inflammatory syndrome (IRIS) due to the opening of the blood-brain barrier. Often, the processes of differential diagnosis of IRIS and natalizumab-associated PML are complex and require the use of additional methods of examination and monitoring of the dynamics of the patient's condition. However, the severity of the condition and the severity of the consequences caused by incorrect therapeutic tactics significantly reduce the time for diagnosis and require an immediate decision. The difficulties of differential diagnosis of IRIS and PML are reflected in the clinical case.

High effector-memory CD8+ T-cell levels correlate with high PML risk in natalizumab-treated patients

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a severe complication of natalizumab (NTZ) treatment in multiple sclerosis (MS) patients. Based on the analysis of cryopreserved cells, several reports have showed that CD62L+ CD4+ T-cells percentage drops before PML onset.

OBJECTIVE

To analyze CD62L and CD45RA expression on fresh-blood CD4+ and CD8+ T-cells from NTZ-treated patients, according to their estimated PML risk.

METHODS

We prospectively enrolled 74 MS patients, including 62 NTZ-treated, and stratified them into low, intermediate and high PML risk groups. Circulating naïve and memory T-cell subsets were analyzed by flow cytometry.

RESULTS

We found no correlation between the percentage of CD62L+ CD4+ T-cells and PML risk. In contrast, the repartition of CD8+ T-cells subpopulations was altered in the high risk group: both the percentage and absolute count of CD8+ CD62L- CD45RA- effector memory T- cells (T_EM) was significantly higher compared to patients at lower risk despite similar CD3+ and CD8+ T-cell counts. One high-risk patient with elevated CD8+ T_EM and CD62L+ CD4+ T-cell levels developed PML six months after sampling.

CONCLUSION

Our results suggest that CD8+ T_EM cells should be evaluated in larger studies as a potential surrogate marker of PML risk in NTZ-treated patients.

Progressive multifocal leukoencephalopathy presenting with acute sensorineural hearing loss in an intestinal transplant recipient

A 20-year-old male presented 3.5 years after intestinal transplantation with rapidly progressive sensorineural hearing loss. Initial brain imaging was consistent with inflammation and/or demyelination. Lumbar puncture was initially non-diagnostic and a broad infectious workup was unrevealing. Three months after presentation, a repeat LP detected JC virus for which tests had not earlier been conducted. He continued to deteriorate despite withdrawal of prior immunosuppression and addition of mirtazapine, maraviroc, and steroids. He died of progressive neurologic decompensation 5 months after his initial presentation. This case highlights progressive multifocal leukoencephalopathy (PML) as a rare complication after solid organ transplantation and acute sensorineural hearing loss as an unusual first presenting symptom of PML. JC virus should be considered in the differential diagnosis of acute sensorineural hearing loss in any immunocompromised patient.

Host-Immune Interactions in JC Virus Reactivation and Development of Progressive Multifocal Leukoencephalopathy (PML)

With the advent of immunomodulatory therapies and the HIV epidemic, the impact of JC Virus (JCV) on the public health system has grown significantly due to the increased incidence of Progressive Multifocal Leukoencephalopathy (PML). Currently, there are no pharmaceutical agents targeting JCV infection for the treatment and the prevention of viral reactivation leading to the development of PML. As JCV primarily reactivates in immunocompromised patients, it is proposed that the immune system (mainly the cellular-immunity component) plays a key role in the regulation of JCV to prevent productive infection and PML development. However, the exact mechanism of JCV immune regulation and reactivation is not well understood. Likewise, the impact of host factors on JCV regulation and reactivation is another understudied area. Here we discuss the current literature on host factor-mediated and immune factor-mediated regulation of JCV gene expression with the purpose of developing a model of the factors that are bypassed during JCV reactivation, and thus are potential targets for the development of therapeutic interventions to suppress PML initiation. Graphical Abstract.

Not a Disease of the Past: A Case Series of Progressive Multifocal Leukoencephalopathy in the Established Antiretroviral Era

Progressive multifocal leukoencephalopathy (PML) and PML immune reconstitution inflammatory syndrome (PML-IRIS) can be devastating neurological processes associated with HIV, but limited knowledge of their characteristics in the established antiretroviral therapy (ART) era is available. We conducted a case series to evaluate the clinical course of PML and PML-IRIS at our urban safety-net hospital in Atlanta, GA. All HIV-positive individuals with a positive John Cunningham virus DNA polymerase chain reaction in the spinal fluid between May 1, 2013 to June 1, 2017 were identified from the electronic health records (EHRs) using the HIV Disease Registry. Demographics, symptom presentation, laboratory data, imaging results, treatment, and outcomes were abstracted from the EHR. PML and PML-IRIS were defined using the American Association of Neurology criteria. Of the 32 individuals identified, 6 (19%) were felt to have asymptomatic positive results. Of the remainder, 15 (58%) HIV-positive patients had PML and 11 (42%) PML-IRIS (2 with an unmasking presentation and 9 with a paradoxical presentation). The most common presenting symptoms were motor weakness (18, 69%), cognitive deficits (15, 58%), and dysarthria (11, 42%). Corticosteroids were used in 12 patients and maraviroc in 3 patients. Outcomes were dismal with 7 (47%) patients with PML and 9 (82%) with PML-IRIS dying or being referred to hospice, with median survival times of 266 days in the PML group and 109 days in the PML-IRIS group. Despite widespread access to ART, patients with PML continue to have poor outcomes, particularly among those who develop PML-IRIS. More research is needed to understand the risks for and prevention of PML-IRIS.

Aging and lymphocyte changes by immunomodulatory therapies impact PML risk in multiple sclerosis patients

New potent immunomodulatory therapies for multiple sclerosis (MS) are associated with increased risk for progressive multifocal leukoencephalopathy (PML). It is unclear why a subset of treated patients develops PML, but patient age has emerged as an important risk factor. PML is caused by the JC virus and aging is associated with immune senescence, which increases susceptibility to infection. With the goal of improving PML risk stratification, we here describe the lymphocyte changes that occur with disease-modifying therapies (DMTs) associated with high or moderate risk toward PML in MS patients, how these changes compare to immune aging, and which measures best correlate with risk. We reviewed studies examining how these therapies alter patient immune profiles, which revealed the induction of changes to lymphocyte number and/or function that resemble immunosenescence. Therefore, the immunosuppressive activity of these MS DMTs may be enhanced in the context of an immune system that is already exhibiting features of senescence.

The C-C Chemokines CCL17 and CCL22 and Their Receptor CCR4 in CNS Autoimmunity

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). It affects more than two million people worldwide, mainly young adults, and may lead to progressive neurological disability. Chemokines and their receptors have been shown to play critical roles in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a murine disease model induced by active immunization with myelin proteins or transfer of encephalitogenic CD4⁺ T cells that recapitulates clinical and neuropathological features of MS. Chemokine ligand-receptor interactions orchestrate leukocyte trafficking and influence multiple pathophysiological cellular processes, including antigen presentation and cytokine production by dendritic cells (DCs). The C-C class chemokines 17 (CCL17) and 22 (CCL22) and their C-C chemokine receptor 4 (CCR4) have been shown to play an important role in homeostasis and inflammatory responses. Here, we provide an overview of the involvement of CCR4 and its ligands in CNS autoimmunity. We review key clinical studies of MS together with experimental studies in animals that have demonstrated functional roles of CCR4, CCL17, and CCL22 in EAE pathogenesis. Finally, we discuss the therapeutic potential of newly developed CCR4 antagonists and a humanized anti-CCR4 antibody for treatment of MS.

[Immune reconstitution inflammatory syndrome and rebound syndrome in multiple sclerosis patients who stopped disease modification therapy: current understanding and a case report]

More and more multiple sclerosis patients have been receiving treatment with new immunomodulatory drugs. Its discontinuation because of side-effects, lack of efficacy or pregnancy has been increasing as well. This paper reviews such severe complications of natalizumab and fingolimod cessation as immune reconstitution inflammatory syndrome (IRIS) and rebound. The short history, immunopathogenesis and diagnostic criteria of IRIS in individuals with human immunodeficiency virus infection are covered. Clinical and radiological presentations as well as possible pathogenic mechanisms of IRIS in patients treated with natalizumab and fingolimod are discussed. The authors also report the case of a woman with multiple sclerosis treated with fingolimod, who experienced a severe relapse when she stopped treatment. Diagnostic criteria and prognostic factors for IRIS and rebound are needed in patients with multiple sclerosis who discontinue the new disease modification therapy.

Drug-associated progressive multifocal leukoencephalopathy: a clinical, radiological, and cerebrospinal fluid analysis of 326 cases

The implementation of a variety of immunosuppressive therapies has made drug-associated progressive multifocal leukoencephalopathy (PML) an increasingly prevalent clinical entity. The purpose of this study was to investigate its diagnostic characteristics and to determine whether differences herein exist between the multiple sclerosis (MS), neoplasm, post-transplantation, and autoimmune disease subgroups. Reports of possible, probable, and definite PML according to the current diagnostic criteria were obtained by a systematic search of PubMed and the Dutch pharmacovigilance database. Demographic, epidemiologic, clinical, radiological, cerebrospinal fluid (CSF), and histopathological features were extracted from each report and differences were compared between the disease categories. In the 326 identified reports, PML onset occurred on average 29.5 months after drug introduction, varying from 14.2 to 37.8 months in the neoplasm and MS subgroups, respectively. The most common overall symptoms were motor weakness (48.6 %), cognitive deficits (43.2 %), dysarthria (26.3 %), and ataxia (24.1 %). The former two also constituted the most prevalent manifestations in each subgroup. Lesions were more often localized supratentorially (87.7 %) than infratentorially (27.4 %), especially in the frontal (64.1 %) and parietal lobes (46.6 %), and revealed enhancement in 27.6 % of cases, particularly in the MS (42.9 %) subgroup. Positive JC virus results in the first CSF sample were obtained in 63.5 %, while conversion after one or more negative outcomes occurred in 13.7 % of cases. 52.2 % of patients died, ranging from 12.0 to 83.3 % in the MS and neoplasm subgroups, respectively. In conclusion, despite the heterogeneous nature of the underlying diseases, motor weakness and cognitive changes were the two most common manifestations of drug-associated PML in all subgroups. The frontal and parietal lobes invariably constituted the predilection sites of drug-related PML lesions.

Therapeutics targeting inflammation in the immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) is characterized by improvement in a previously incompetent human immune system manifesting as worsening of clinical symptoms secondary to the ability of the immune system to now mount a vigorous inflammatory response. IRIS was first recognized in the setting of human immunodeficiency virus, and this clinical setting continues to be where it is most frequently encountered. Hallmarks of the pathogenesis of IRIS, independent of the clinical presentation and the underlying pathogen, include excessive activation of the immune system, with increased circulating effector memory T cells, and elevated levels of serum cytokines and inflammatory markers. Patients with undiagnosed opportunistic infections remain at risk for unmasking IRIS at the time of active antiretroviral therapy (ART) initiation. Systematic screening for opportunistic infections before starting ART is a key element to prevent this phenomenon. Appropriate management of IRIS requires prompt recognition of the syndrome and exclusion of alternative diagnoses, particularly underlying infections and drug resistance. Controlled studies supporting the use of pharmacologic interventions in IRIS are scare, and recommendations are based on case series and expert opinions. The only controlled trial published to date, showed reduction in morbidity in patients with paradoxical tuberculosis-related IRIS with the use of oral corticosteroids. There are currently limited data to recommend other anti-inflammatory or immunomodulatory therapies that are discussed in this review, and further research is needed. Ongoing research regarding the immune pathogenesis of IRIS will likely direct future rational therapeutic approaches and clinical trials.

Progressive multifocal leukoencephalopathy and immune reconstitution inflammatory syndrome (IRIS)

Progressive multifocal leukoencephalopathy is a viral encephalitis induced by the John Cunningham (JC) virus, an ubiquitous neurotropic papovavirus of the genus polyomavirus that in healthy people in latency resides in kidney and bone marrow cells. Activation and entry into the CNS were first seen in patients with malignancies of the hematopoietic system and an impaired immune system. During the 1980 and the 1990s with the appearance of human immunodeficiency virus infection in humans, PML was found to be the most important opportunistic infection of the central nervous system. As a result of highly efficient immunosuppressive and immunomodulatory treatments, in recent years, the number of PML cases again increased. PML is prevented by an intact cellular immune response and accordingly immune reconstitution can terminate established disease in the CNS. However, forced immune reconstitution can lead to massive destruction of virus-infected cells. This may result in clinical exacerbation associated with high morbidity and mortality and referred to as PML with immune reconstitution inflammatory syndrome (PML-IRIS). In the present review, we discuss virological properties and routes of infection in the CNS, but mostly focus on the pathology of PML and PML-IRIS and on the role of the immune system in these disorders. We show that PML and PML-IRIS result from predominant JC virus infection of oligodendrocytes and, to a lesser extent, of infected neurons. Inflammation in these encephalitides seems to be driven by a dominant cytotoxic T cell response which is massively exaggerated during IRIS.

Progressive multifocal leukoencephalopathy: current treatment options and future perspectives

Progressive multifocal leukoencephalopathy (PML) is a rare but debilitating and frequently fatal viral disease of the central nervous system, primarily affecting individuals with chronically and severely suppressed immune systems. The disease was relatively obscure until the outbreak of HIV/AIDS, when it presented as one of the more frequent opportunistic infections in this immune deficiency syndrome. It attracted additional attention from the medical and scientific community following the discovery of significant PML risk associated with natalizumab, a monoclonal antibody used for treatment of relapsing-remitting multiple sclerosis. This was followed by association of PML with other immunosuppressive or immunomodulating drugs. PML is currently untreatable disease with poor outcomes, so it is a significant concern when developing new immunotherapies. Current prophylaxis and treatment of PML are focused on immune reconstitution, restoration of immune responses to JC virus infection, and eventual suppression of immune reconstitution inflammatory syndrome. This approach was successful in reducing the incidence of PML and improved survival of PML patients with HIV infection. However, the outcome for the majority of PML patients, regardless of their medical history, is still relatively poor. There is a high unmet need for both prophylaxis and treatment of PML. The aim of this review is to discuss potential drug candidates for prophylaxis and treatment of PML with a critical review of previously conducted and completed PML treatment studies as well as to provide perspectives for future therapies.

Upregulation of integrin expression on monocytes in multiple sclerosis patients treated with natalizumab

Natalizumab is a humanized monoclonal antibody against the α4 subunit of VLA-4 integrin that is used to treat conditions such as multiple sclerosis (MS). Although its effects on lymphocytes have been widely described, little is known about its effects on monocytes. Here we described the effects of natalizumab treatment on peripheral blood monocytes from a small cohort of MS patients in terms of relative frequencies and surface integrin (CD49d and CD18) expression. We showed that natalizumab treatment altered the surface integrin expression on monocyte subsets in the peripheral compartment, suggesting a role for them as mediators of natalizumab effects.

Immune reconstitution inflammatory syndrome associated with biologic therapy

The use of biologics in the treatment of autoimmune disease, cancer, and other immune conditions has revolutionized medical care in these areas. However, there are drawbacks to the use of these medications including increased susceptibility to opportunistic infections. One unforeseen risk once opportunistic infection has occurred with biologic use is the onset of immune reconstitution inflammatory syndrome (IRIS) upon drug withdrawal. Although originally described in human immunodeficiency virus (HIV) patients receiving highly active antiretroviral therapy, it has become clear that IRIS may occur when recovery of immune function follows opportunistic infection in the setting of previous immune compromise/suppression. In this review, we draw attention to this potential pitfall on the use of biologic drugs.

Assessment of immune functions and MRI disease activity in relapsing-remitting multiple sclerosis patients switching from natalizumab to fingolimod (ToFingo-Successor)

BACKGROUND

In light of the increased risk of progressive multifocal encephalopathy (PML) development under long-term treatment with the monoclonal antibody natalizumab which is approved for treatment of active relapsing remitting multiple sclerosis (RRMS), there is a clear need for alternative treatment options with comparable efficacy and reduced PML risk. One such option is fingolimod, a functional sphingosin-1-receptor antagonist that has been approved as first oral drug for treatment of active RRMS. However, the optimal switching design in terms of prevention of disease reoccurrence is still unknown. Moreover, potential additive effects of both drugs on immune functions, especially with regard to migration, have not yet been evaluated.

METHODS/DESIGN

This is an exploratory, open-label, monocentric, investigator-initiated clinical trial. Fifteen RRMS patients under stable treatment with natalizumab will receive one last natalizumab infusion followed by a wash-out period of 8 weeks before fingolimod treatment initiation for a period of 24 weeks. Disease activity under natalizumab and during switching will be closely monitored by assessment of relapse rate and disease severity as well as high-frequent high-resolution magnetic resonance imaging including quantitative diffusion tensor imaging. Immunological assays include longitudinal assessment of adhesion molecule expression, functional evaluation of the migratory capacity of immune cells in an in-vitro model of the blood-brain-barrier, and the quality of cellular antiviral immune responses.

DISCUSSION

Our trial represents the first detailed and longitudinal functional analysis of key immunological parameters in the process of switching from natalizumab and fingolimod, especially with regard to potential additive effects of both drugs on trafficking and immune surveillance. Moreover, our study will generate valuable information about even subtle disease exacerbations as consequence of natalizumab cessation, which will help to understand whether a switching protocol containing a wash-out period of 8 weeks before fingolimod treatment is appropriate in terms of disease stability.

Immune reconstitution inflammatory syndrome in a patient with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a severe opportunistic infection of the central nervous system. A 52-year-old man with HIV infection, recently started on antiretroviral therapy, presented with symptoms of mental cloudiness, blurry vision and ataxia. MRI of the brain showed nodular perivascular space enhancement with surrounding vasogenic oedema and midline shift. A lumbar puncture revealed non-inflammatory cerebrospinal fluid and was positive for JC virus. As the patient developed worsening symptoms in the setting of initiation of antiretroviral therapy with immune recovery, a diagnosis of JC virus-associated immune reconstitution inflammatory syndrome (IRIS) was made. With recent literature on the use of CCR5 antagonist maraviroc in PML, our patient was started on maraviroc and noted to have improvement in PML IRIS. This is the first case of an HIV-positive patient successfully treated for PML IRIS with maraviroc, as verified by our literature review; also, our case has clinical implications in improving outcome in PML IRIS.

Fingolimod treatment promotes regulatory phenotype and function of B cells

OBJECTIVE

To evaluate the influence of Fingolimod treatment on B-cell subset composition and function in multiple sclerosis patients and its potential clinical relevance.

METHODS

Subset composition and cytokine production of B cells derived from peripheral blood mononuclear cells from multiple sclerosis patients under Fingolimod treatment, untreated multiple sclerosis patients and healthy controls were analyzed by flow cytometry and ELISA. Migration of lymphocyte subsets across primary human brain microvascular endothelial cells was assessed in an in vitro transmigration assay. Cell numbers and composition of B-cell subsets in cerebrospinal fluid and peripheral blood were determined by flow cytometry. Regulatory B-cell frequencies were correlated with parameters of disease stability.

RESULTS

Within the peripheral B-cell compartment of Fingolimod-treated patients, the proportion of regulatory B cells (CD38(+)CD27(-)CD24(+)CD5(+)) was significantly increased as compared to treatment-naïve multiple sclerosis patients and to healthy controls, and significantly more regulatory B cells produced Interleukin-10. Fingolimod treatment enhanced the capacity of regulatory B cells to transmigrate across brain endothelial cells in an in vitro model of the blood-brain-barrier. In line with these findings, the cerebrospinal fluid/blood ratio of total B cells and regulatory B cells was strongly increased by Fingolimod treatment, and patients exhibited increased regulatory B-cell frequencies in the cerebrospinal fluid. Finally, elevated regulatory B-cell percentages in the periphery significantly correlated with clinical and paraclinical disease stability.

INTERPRETATION

These data suggest a novel and as yet unrecognized role of Fingolimod in correction of the imbalance between regulatory and effector B-cell functions in multiple sclerosis both by direct effects and indirect partitioning effects on B-cell subpopulations.

Immunological Markers for PML Prediction in MS Patients Treated with Natalizumab

Natalizumab (NTZ), a monoclonal antibody recognizing the alpha4 integrin chain, has been approved for the treatment of active multiple sclerosis, but expose to the onset of a rare side effect, progressive multifocal leukoencephalopathy (PML). Estimating the individual risk of PML in NTZ-treated patients is a major challenge, and therapeutic strategies are mainly guided by the overall PML risk assessed by identified risk factors: JC virus (JCV) seropositivity, treatment duration (with peak incidence after 24 months), and the previous use of immunosuppressive therapies. Given that this stratification does not yet allow a precise individual prediction of PML, other predictive markers are needed, and several immunological biomarkers have been described. Quantification of anti-JCV antibody levels may improve individual predictive value, with higher baseline titers indicating increased risk. Other immunological biomarkers such as leukocyte cell membrane markers (CD49d, CD11a, and CD62L), detection of circulating JCV-specific activated T effector memory cells (TEM) or genetic screening have been proposed. In this review, we discuss how recent progress in immunology has paved the way for «new combined monitoring», which will include immunological screening, in NTZ-treated patients.

Therapeutic uses of anti-α4-integrin (anti-VLA-4) antibodies in multiple sclerosis

Multiple sclerosis (MS) is a disorder of putative autoimmune origin, where immune cells invade the central nervous system and cause damage by attacking the myelin sheath of nerve cells. The blockade of the integrin very late antigen-4 (VLA-4) with the monoclonal antibody natalizumab has become the most effective therapy against MS since its approval in 2004. It is assumed that the inhibition of VLA-4-mediated immune cell adhesion to the endothelium of the blood-brain barrier (BBB) alleviates pathogenic processes of MS and, therefore, reduces disease severity and burden. Not all approaches to treat additional immune-mediated disorders (e.g. Rasmussen encephalitis and neuromyelitis optica) with natalizumab have been successful, but allowed researchers to gain additional insight into mechanisms of specific immune cell subsets' migration through the BBB in the human system. While the long-term efficacy and general tolerability of natalizumab in MS are clear, the over 400 cases of natalizumab-associated progressive multifocal leukoencephalopathy (PML) have been of great concern and methods of risk stratification in patients have become a major area of research. Modern risk stratification includes established factors such as treatment duration, previous immune-suppressive therapy, and anti-John Cunningham virus (JCV) antibody seropositivity, but also experimental factors such as anti-JCV antibody titers and levels of L-selectin. Today, anti-VLA-4 therapy is reserved for patients with highly active relapsing-remitting MS and patients are monitored closely for early signs of potential PML.

VLA-4 blockade promotes differential routes into human CNS involving PSGL-1 rolling of T cells and MCAM-adhesion of TH17 cells

Schneider-Hohendorf describe expression of adhesion molecules MCAM and PSGL-1 on human CD4⁺ T cells and Th17 T cells in multiple sclerosis patients under long-term natalizumab treatment. The authors identify that despite blockade of VLA-4, MCAM⁺ T cells can migrate through the blood–brain barrier to access the CNS through PSGL-1 and MCAM.

The focus of this study is the characterization of human T cell blood–brain barrier migration and corresponding molecular trafficking signatures. We examined peripheral blood and cerebrospinal fluid immune cells from patients under long-term anti–very late antigen-4 (VLA-4)/natalizumab therapy (LTNT) and from CNS specimens. LTNT patients’ cerebrospinal fluid T cells exhibited healthy central-/effector-memory ratios, but lacked CD49d and showed enhanced myeloma cell adhesion molecule (MCAM) expression. LTNT led to an increase of PSGL-1 expression on peripheral T cells. Although vascular cell adhesion molecule-1 (VLA-4 receptor) was expressed at all CNS barriers, P-selectin (PSGL-1-receptor) was mainly detected at the choroid plexus. Accordingly, in vitro experiments under physiological flow conditions using primary human endothelial cells and LTNT patients’ T cells showed increased PSGL-1–mediated rolling and residual adhesion, even under VLA-4 blockade. Adhesion of MCAM⁺/T_H17 cells was not affected by VLA-4 blocking alone, but was abrogated when both VLA-4 and MCAM were inhibited. Consistent with these data, MCAM⁺ cells were detected in white matter lesions, and in gray matter of multiple sclerosis patients. Our data indicate that lymphocyte trafficking into the CNS under VLA-4 blockade can occur by using the alternative adhesion molecules, PSGL-1 and MCAM, the latter representing an exclusive pathway for T_H17 cells to migrate over the blood–brain barrier.

JC virus reactivation during prolonged natalizumab monotherapy for multiple sclerosis

OBJECTIVE

To determine the prevalence of JC virus (JCV) reactivation and JCV-specific cellular immune response during prolonged natalizumab treatment for multiple sclerosis (MS).

METHODS

We enrolled 43 JCV-seropositive MS patients, including 32 on natalizumab monotherapy >18 months, 6 on interferon β-1a monotherapy >36 months, and 5 untreated controls. We performed quantitative real-time polymerase chain reaction in cerebrospinal fluid (CSF), blood, and urine for JCV DNA, and we determined JCV-specific T-cell responses using enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining (ICS) assays, ex vivo and after in vitro stimulation with JCV peptides.

RESULTS

JCV DNA was detected in the CSF of 2 of 27 (7.4%) natalizumab-treated MS patients who had no symptoms or magnetic resonance imaging-detected lesions consistent with progressive multifocal leukoencephalopathy. JCV DNA was detected in blood of 12 of 43 (27.9%) and in urine of 11 of 43 (25.6%) subjects without a difference between natalizumab-treated patients and controls. JC viral load was higher in CD34(+) cells and in monocytes compared to other subpopulations. ICS was more sensitive than ELISpot. JCV-specific T-cell responses, mediated by both CD4(+) and CD8(+) T lymphocytes, were detected more frequently after in vitro stimulation. JCV-specific CD4(+) T cells were detected ex vivo more frequently in MS patients with JCV DNA in CD34(+) (p = 0.05) and B cells (p = 0.03).

INTERPRETATION

Asymptomatic JCV reactivation may occur in CSF of natalizumab-treated MS patients. JCV DNA load is higher in circulating CD34(+) cells and monocytes compared to other mononuclear cells, and JCV in blood might trigger a JCV-specific CD4(+) T-cell response. JCV-specific cellular immune response is highly prevalent in all JCV-seropositive MS patients, regardless of treatment.

Current approaches to the management of new-onset ulcerative colitis

Ulcerative colitis (UC) is an idiopathic, inflammatory gastrointestinal disease of the colon. As a chronic condition, UC follows a relapsing and remitting course with medical maintenance during periods of quiescent disease and appropriate escalation of therapy during times of flare. Initial treatment strategies must not only take into account current clinical presentation (with specific regard for extent and severity of disease activity) but must also take into consideration treatment options for the long-term. The following review offers an approach to new-onset UC with a focus on early treatment strategies. An introduction to the disease entity is provided along with an approach to initial diagnosis. Stratification of patients based on clinical parameters, disease extent, and severity of illness is paramount to determining course of therapy. Frequent assessments are required to determine clinical response, and treatment intensification may be warranted if expected improvement goals are not appropriately reached. Mild-to- moderate UC can be managed with aminosalicylates, mesalamine, and topical corticosteroids with oral corticosteroids reserved for unresponsive cases. Moderate-to-severe UC generally requires oral or intravenous corticosteroids in the short-term with consideration of long-term management options such as biologic agents (as initial therapy or in transition from steroids) or thiopurines (as bridging therapy). Patients with severe or fulminant UC who are recalcitrant to medical therapy or who develop disease complications (such as toxic megacolon) should be considered for colectomy. Early surgical referral in severe or refractory UC is crucial, and colectomy may be a life-saving procedure. The authors provide a comprehensive evidence-based approach to current treatment options for new-onset UC with discussion of long-term therapeutic efficacy and safety, patient-centered perspectives including quality of life and medication compliance, and future directions in related inflammatory bowel disease care.

Specific loss of cellular L-selectin on CD4(+) T cells is associated with progressive multifocal leukoencephalopathy development during HIV infection

HIV(+) progressive multifocal leukoencephalopathy (PML) patients had a significantly lower expression of CD62L on CD4(+) T cells (P < 0.001) when compared with HIV(+) patients who did not develop PML. CD62L expression on CD4(+) T cells did not correlate with parameters such as CDC stage, CD4(+) cell percentage (of total CD3(+) T cells), CD4(+) cell counts, virus count, or clinical parameters. Measurement of CD62L might provide a biomarker for PML risk and could prompt a treatment change and/or close monitoring.

Natalizumab-associated progressive multifocal leukoencephalopathy in a patient with multiple sclerosis: a postmortem study

Natalizumab, a monoclonal antibody directed against α4 integrins, has, to date, been associated with 399 cases of progressive multifocal leukoencephalopathy (PML) worldwide in patients receiving treatment for multiple sclerosis (MS). Because of the limited number of histologic studies, the possible interplay between MS and PML lesions has not been investigated. We report the clinical, radiologic, and histologic findings of an MS patient who developed PML after 32 months of natalizumab monotherapy. After withdrawal of natalizumab, she received plasma exchange, mefloquine, and mirtazapine but died soon thereafter. Postmortem examination was restricted to examination of the brain and spinal cord. Extensive PML lesions, characterized by the presence of JC virus DNA were found in the cerebral white matter and neocortex. Sharply demarcated areas of active PML lesions contained prominent inflammatory infiltrates composed of approximately equal numbers of CD4-positive and CD8-positive T cells, consistent with an immune reconstitution inflammatory syndrome. Conversely, all MS lesions identified were hypocellular, long-standing inactive plaques characterized by myelin loss, relative axonal preservation, and gliosis and, importantly, were devoid of JC virus DNA and active inflammation. Chronic inactive MS lesions were separate and distinct from nearby PML lesions. This case demonstrates the coexistence and apparent lack of interplay between chronic inactive MS and PML lesions, and that immune reconstitution inflammatory syndrome seems to affect the shape and appearance of PML but not MS lesions.

Central nervous system immune reconstitution inflammatory syndrome

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) develops in 9 %-47 % of persons with HIV infection and a CNS opportunistic infection who start antiretroviral therapy and is associated with a mortality rate of 13 %-75 %. These rates vary according to the causative pathogen. Common CNS-IRIS events occur in relation to Cryptococcus, tuberculosis (TB), and JC virus, but several other mycobacteria, fungi, and viruses have been associated with IRIS. IRIS symptoms often mimic the original infection, and diagnosis necessitates consideration of treatment failure, microbial resistance, and an additional neurological infection. These diagnostic challenges often delay IRIS diagnosis and treatment. Corticosteroids have been used to treat CNS-IRIS, with variable responses; the best supportive evidence exists for the treatment of TB-IRIS. Pathogenic mechanisms vary: Cryptococcal IRIS is characterized by a paucity of cerebrospinal inflammation prior to antiretroviral therapy, whereas higher levels of inflammatory markers at baseline predispose to TB meningitis IRIS. This review focuses on advances in the understanding of CNS-IRIS over the past 2 years.

Reported outcomes after the endovascular treatment of chronic cerebrospinal venous insufficiency

Chronic cerebrospinal venous insufficiency (CCSVI) has recently been implicated as a potential causal factor in the development of multiple sclerosis (MS). The treatment of jugular and azygous vein stenoses, characteristic of CCSVI, has been proposed as a potential component of therapy for MS. In the few short years since Dr. Paulo Zamboni published "A Prospective Open label Study of Endovascular Treatment of Chronic Cerebrospinal Venous Insufficiency", there has been tremendous patient-driven demand for treatment. Concurrently, there have been numerous publications since 2009 addressing CCSVI and its association with MS. The purpose of this article is to present a brief review of CCSVI and its association with MS and to review the available literature to date with a focus on outcomes data.

Peripheral accumulation of newly produced T and B lymphocytes in natalizumab-treated multiple sclerosis patients

The anti-α4 monoclonal antibody natalizumab inhibits lymphocyte extravasation into the central nervous system and increases peripheral T and B lymphocytes in multiple sclerosis patients. To investigate whether the lymphocyte accumulation was due to a higher lymphocyte production, an altered homeostasis, or a differential transmigration of lymphocyte subsets through endothelia, T-cell receptor excision circles and kappa-deleting recombination excision circles were quantified before and after treatment, T-cell receptor repertoire was analyzed by spectratyping, and T- and B-lymphocyte subset migration was studied using transwell coated with vascular and lymphatic endothelial cells. We found that the number of newly produced T and B lymphocytes is increased because of a high release and of a low propensity of naïve subsets to migrate across endothelial cells. In some patients this resulted in an enlargement of T-cell heterogeneity. Because new lymphocyte production ensures the integrity of immune surveillance, its quantification could be used to monitor natalizumab therapy safety.

Pathology of immune reconstitution inflammatory syndrome in multiple sclerosis with natalizumab-associated progressive multifocal leukoencephalopathy

Natalizumab is an approved medication for highly active multiple sclerosis (MS). Progressive multifocal leukoencephalopathy (PML) may occur as a severe side effect of this drug. Here, we describe pathological and radiological characteristics of immune reconstitution inflammatory syndrome (IRIS), which occurs in natalizumab-associated PML after the cessation of therapy, and we differentiate it from ongoing PML. Brain biopsy tissue and MRI scans from five MS patients with natalizumab-associated PML were analyzed and their histology compared with non-MS PML. Histology showed an extensive CD8-dominated T cell infiltrate and numerous macrophages within lesions, and in nondemyelinated white and grey matter, in four out of five cases. Few or no virally infected cells were found. This was indicative of IRIS as known from HIV patients with PML. Outstandingly high numbers of plasma cells were present as compared to non-MS PML and typical MS lesions. MRI was compatible with IRIS, revealing enlarging lesions with a band-like or speckled contrast enhancement either at the lesion edge or within lesions. Only the fifth patient showed typical PML pathology, with low inflammation and high numbers of virally infected cells. This patient showed a similar interval between drug withdrawal and biopsy (3.5 months) to the rest of the cohort (range 2.5-4 months). MRI could not differentiate between PML-associated IRIS and ongoing PML. We describe in detail the histopathology of IRIS in natalizumab-associated PML. PML-IRIS, ongoing PML infection, and MS exacerbation may be impossible to discern clinically alone. MRI may provide some clues for distinguishing different pathologies that can be differentiated histologically. In our individual cases, biopsy helped to clarify diagnoses in natalizumab-associated PML.