Progressive multifocal leukoencephalopathy and natalizumab

Intact natalizumab pharmacokinetics is impacted by endogenous IgG4 concentration

BACKGROUND

Natalizumab (NAT) pharmacokinetics and pharmacodynamics are complicated by arm exchange with endogenous IgG4, resulting in a mixture of a more potent intact, bivalent form and a less potent, functionally monovalent form. Total NAT and endogenous IgG4 concentrations vary considerably across patients. This study assessed the concentration of intact NAT, and how it relates to total NAT and endogenous IgG4 levels in blood and saliva.

METHODS

Paired serum and saliva samples from a small cohort of relapsing-remitting multiple sclerosis patients were measured for levels of intact NAT, total NAT, IgG and IgG4.

RESULTS

Intact NAT concentration was dependent on both total NAT and endogenous IgG4 levels. Low endogenous IgG4 led to a higher ratio of intact NAT to total NAT, while the opposite was observed in subjects with high endogenous IgG4. Serum and saliva measurements show good concordance.

CONCLUSIONS

Intact NAT concentration is influenced by both NAT pharmacokinetics and endogenous IgG4 levels. Patients with low IgG4 levels can have high concentrations of intact NAT even with lower levels of total NAT, which may explain cases of NAT-associated progressive multifocal leukoencephalopathy (PML) in such patients. Monitoring both forms of NAT could better guide dosing, maximizing drug efficacy and safety.

Integrin α3 promotes TH17 cell polarization and extravasation during autoimmune neuroinflammation

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) caused by CNS-infiltrating leukocytes, including TH17 cells that are critical mediators of disease pathogenesis. Although targeting leukocyte trafficking is effective in treating autoimmunity, there are currently no therapeutic interventions that specifically block encephalitogenic TH17 cell migration. Here, we report integrin α3 as a TH17 cell-selective determinant of pathogenicity in experimental autoimmune encephalomyelitis. CNS-infiltrating TH17 cells express high integrin α3, and its deletion in CD4+ T cells or Il17a fate-mapped cells attenuated disease severity. Mechanistically, integrin α3 enhanced the immunological synapse formation to promote the polarization and proliferation of TH17 cells. Moreover, the transmigration of TH17 cells into the CNS was dependent on integrin α3, and integrin α3 deficiency enhanced the retention of CD4+ T cells in the perivascular space of the blood-brain barrier. Integrin α3-dependent interactions continuously maintain TH17 cell identity and effector function. The requirement of integrin α3 in TH17 cell pathogenicity suggests integrin α3 as a therapeutic target for MS treatment.

Pharmacological Therapy in Inflammatory Bowel Diseases: A Narrative Review of the Past 90 Years

Inflammatory Bowel Diseases had their first peak in incidence in countries in North America, Europe, and Oceania and are currently experiencing a new acceleration in incidence, especially in Latin America and Asia. Despite technological advances, 90 years after the development of the first molecule for the treatment of IBD, we still do not have drugs that promote disease remission in a generalized way. We carried out a narrative review on therapeutic advances in the treatment of IBD, the mechanisms of action, and the challenges facing the therapeutic goals in the treatment of IBD. Salicylates are still used in the treatment of Ulcerative Colitis. Corticosteroids have an indication restricted to the period of therapeutic induction due to frequent adverse events, while technologies with less systemic action have been developed. Most immunomodulators showed a late onset of action, requiring a differentiated initial strategy to control the disease. New therapeutic perspectives emerged with biological therapy, initially with anti-TNF, followed by anti-integrins and anti-interleukins. Despite the different mechanisms of action, there are similarities between the general rates of effectiveness. These similar results were also evidenced in JAK inhibitors and S1p modulators, the last therapeutic classes approved for the treatment of IBD.

Peptide Mimotope-Enabled Quantification of Natalizumab Arm Exchange During Multiple Sclerosis Treatment

BACKGROUND

Natalizumab, a therapeutic antibody used to treat multiple sclerosis, undergoes in vivo Fab arm exchange to form a monovalent bispecific antibody. Although highly efficacious, the immunosuppressive activity of natalizumab has been associated with JC polyomavirus-driven progressive multifocal leukoencephalopathy (PML). Development of assays that can distinguish between and quantify bivalent (unexchanged) and monovalent (exchanged) forms of natalizumab in clinical samples may be useful for optimizing extended interval dosing and reducing the risk of PML.

METHODS

In vitro natalizumab arm exchange was conducted, along with peptide mimotope and anti-idiotype surface capture chemistry, to enable the development of enzyme-linked immunosorbent assays.

RESULTS

An assay using a unique peptide Veritope TM was developed, which can exclusively bind to bivalent natalizumab. In combination with enzyme-linked immunosorbent assays that quantifies total natalizumab, the assay system allows quantification of both natalizumab forms.

CONCLUSIONS

In this article, a novel assay for the quantification of unexchanged and exchanged natalizumab variants in clinical samples was developed. This assay will enable investigations into the clinical significance of the relationship of PK/PD with the monovalent-to-bivalent ratio, as it relates to the efficacy of the drug and risk of PML.

Specificity of Adaptive Immune Responses in Central Nervous System Health, Aging and Diseases

The field of neuroimmunology endorses the involvement of the adaptive immune system in central nervous system (CNS) health, disease, and aging. While immune cell trafficking into the CNS is highly regulated, small numbers of antigen-experienced lymphocytes can still enter the cerebrospinal fluid (CSF)-filled compartments for regular immune surveillance under homeostatic conditions. Meningeal lymphatics facilitate drainage of brain-derived antigens from the CSF to deep cervical lymph nodes to prime potential adaptive immune responses. During aging and CNS disorders, brain barriers and meningeal lymphatic functions are impaired, and immune cell trafficking and antigen efflux are altered. In this context, alterations in the immune cell repertoire of blood and CSF and T and B cells primed against CNS-derived autoantigens have been observed in various CNS disorders. However, for many diseases, a causal relationship between observed immune responses and neuropathological findings is lacking. Here, we review recent discoveries about the association between the adaptive immune system and CNS disorders such as autoimmune neuroinflammatory and neurodegenerative diseases. We focus on the current challenges in identifying specific T cell epitopes in CNS diseases and discuss the potential implications for future diagnostic and treatment options.

Progression of a series of patients with relapsing-remitting multiple sclerosis treated for 7 years with natalizumab using the "no evidence of disease activity" parameter

INTRODUCTION

The safety and effectiveness of natalizumab in patients with relapsing-remitting multiple sclerosis (RRMS) has been demonstrated in clinical trials. However, due to the limitations of these trials, it is important to know how the condition behaves under long-term clinical practice conditions.

OBJECTIVE

To determine the long-term effectiveness of natalizumab in patients with RRMS by means of annual evaluation of the "no evidence of disease activity" (NEDA) parameter, which includes number of relapses, disability (measured with the Expanded Disability Status Scale), and brain MRI parameters.

PATIENTS AND METHODS

We performed a retrospective study of patients with RRMS from 3 centres who were treated with one or more doses of natalizumab. Each year, we evaluated NEDA status and safety based on the percentage of patients who discontinued treatment with natalizumab and experienced adverse reactions.

RESULTS

The study included 89 patients, most of whom received treatment for 2 to 4 years, with a follow-up period of up to 7 years. Natalizumab significantly reduces the radiological and clinical progression of the disease, as well as the annual rate of relapses. The NEDA parameter demonstrates the effectiveness of the drug, with values of 75.28% for year one and 66.67% for year 7. Twenty-five patients (28.1%) dropped out after a median of 4 years. Fourteen of these patients (56%) dropped out due to the appearance of anti-JC virus antibodies, either in isolation or associated with another cause. Four dropouts (16%) were due to treatment ineffectiveness, with one patient dying due to progressive multifocal leukoencephalopathy.

CONCLUSIONS

Natalizumab is highly effective as measured by the NEDA long-term remission parameter.

Safety outcomes of disease-modifying therapies for relapsing-remitting multiple sclerosis: A network meta-analysis

BACKGROUND

Randomised clinical trials (RCTs) and observational studies have reported adverse events that preclude the use of disease-modifying therapies (DMTs) in relapsing-remitting multiple sclerosis (RRMS) in the long term or in specific populations, however, little is known about the relationship between the use of DMTs and frequency of undesirable events. We aimed to conduct a systematic review and network meta-analyses (NMAs) of RCTs and observational studies to synthesise the evidence on the safety of all available DMTs for patients with RRMS.

METHODS

PubMed, Scopus and a manual search were performed. Bayesian NMAs of safety outcomes reported in RCTs and observational studies assessing DMTs as monotherapies were conducted.

RESULTS

Forty-seven studies were included in the systematic review. Considering all studies, 368 and 149 different safety outcomes were reported for at least one study and two studies, respectively. Considering clinical trials, 22 NMAs were conducted for 16 outcomes. Regarding geometry metrics, the median number of studies, DMTs, common comparator, strong edge, and patients were 5 (IQR 5-9), 5 (IQR 4-8), 44%, 33%, and 3998 (IQR 3380-6761). In summary, most comparisons showed similar risk of safety events for DMTs and placebo for all outcomes. Considering cohort studies, only three meta-analyses were conducted.

CONCLUSION

Safety outcomes are poorly reported in primary studies of DMTs in RRMS, precluding the conduction of robust meta-analyses. Therefore, the current available data on safety of these drugs is not contributing to regulatory and clinical decision making, with adverse event reports underbalanced compared to efficacy outcomes.

A Cell-Based Approach to the Treatment of Inflammatory Bowel Disease-Entering an Era of Regenerative Medicine

Corticosteroids, and more recently biologics, have been the mainstay of therapy for patients with inflammatory bowel disease. Unfortunately, both are fraught with side effects and limited by lack of efficacy or loss of response. Many patients ultimately succumb to medically refractory disease and require an operation. As we enter an era of regenerative medicine, a new genre of cell-based therapeutics offers significant promise for both an improved safety profile and improved efficacy compared with conventional treatment approaches. The ability to restore and rebuild health with autologous products rather than react to disease with pharmaceuticals gives hope to those who treat inflammatory bowel disease. The rationale and ongoing trials in an emerging field of medicine-regenerative medicine-is herein discussed.

Virus-Receptor Interactions: The Key to Cellular Invasion

Virus–receptor interactions play a key regulatory role in viral host range, tissue tropism, and viral pathogenesis. Viruses utilize elegant strategies to attach to one or multiple receptors, overcome the plasma membrane barrier, enter, and access the necessary host cell machinery. The viral attachment protein can be viewed as the “key” that unlocks host cells by interacting with the “lock”—the receptor—on the cell surface, and these lock-and-key interactions are critical for viruses to successfully invade host cells. Many common themes have emerged in virus–receptor utilization within and across virus families demonstrating that viruses often target particular classes of molecules in order to mediate these events. Common viral receptors include sialylated glycans, cell adhesion molecules such as immunoglobulin superfamily members and integrins, and phosphatidylserine receptors. The redundancy in receptor usage suggests that viruses target particular receptors or “common locks” to take advantage of their cellular function and also suggests evolutionary conservation. Due to the importance of initial virus interactions with host cells in viral pathogenesis and the redundancy in viral receptor usage, exploitation of these strategies would be an attractive target for new antiviral therapeutics.

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Viral receptors are key regulators of host range, tissue tropism, and viral pathogenesis.

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Many viruses utilize common viral receptors including sialic acid, cell adhesion molecules such as immunoglobulin superfamily members and integrins, and phosphatidylserine receptors.

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Detailed molecular interactions between viruses and receptors have been defined through elegant biochemical analyses including glycan array screens, structural–functional analyses, and cell-based approaches providing tremendous insights into these initial events in viral infection.

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Commonalities in virus–receptor interactions present promising targets for the development of broad-spectrum antiviral therapies.

Progression of a series of patients with relapsing-remitting multiple sclerosis treated for 7 years with natalizumab using the "no evidence of disease activity" parameter

INTRODUCTION

The safety and effectiveness of natalizumab in patients with relapsing-remitting multiple sclerosis (RRMS) has been demonstrated in clinical trials. However, due to the limitations of these trials, it is important to know how the condition behaves under long-term clinical practice conditions.

OBJECTIVE

To determine the long-term effectiveness of natalizumab in patients with RRMS by means of annual evaluation of the "no evidence of disease activity" (NEDA) parameter, which includes number of relapses, disability (measured with the Expanded Disability Status Scale), and brain MRI parameters.

PATIENTS AND METHODS

We performed a retrospective study of patients with RRMS from 3 centres who were treated with one or more doses of natalizumab. Each year, we evaluated NEDA status and safety based on the percentage of patients who discontinued treatment with natalizumab and experienced adverse reactions.

RESULTS

The study included 89 patients, most of whom received treatment for 2 to 4 years, with a follow-up period of up to 7 years. Natalizumab significantly reduces the radiological and clinical progression of the disease, as well as the annual rate of relapses. The NEDA parameter demonstrates the effectiveness of the drug, with values of 75.28% for year one and 66.67% for year 7. Twenty-five patients (28.1%) dropped out after a median of 4 years. Fourteen of these patients (56%) dropped out due to the appearance of anti-JC virus antibodies, either in isolation or associated with another cause. Four dropouts (16%) were due to treatment ineffectiveness, with one patient dying due to progressive multifocal leukoencephalopathy.

CONCLUSIONS

Natalizumab is highly effective as measured by the NEDA long-term remission parameter.

ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biological therapies: an infectious diseases perspective (Immune checkpoint inhibitors, cell adhesion inhibitors, sphingosine-1-phosphate receptor modulators and proteasome inhibitors)

BACKGROUND

The present review is part of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Infections in Compromised Hosts (ESGICH) consensus document on the safety of targeted and biological therapies.

AIMS

To review, from an infectious diseases perspective, the safety profile of immune checkpoint inhibitors, LFA-3-targeted agents, cell adhesion inhibitors, sphingosine-1-phosphate receptor modulators and proteasome inhibitors, and to suggest preventive recommendations.

SOURCES

Computer-based Medline searches with MeSH terms pertaining to each agent or therapeutic family.

CONTENT

T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death (PD)-1/PD-1 ligand 1 (PD-L1)-targeted agents do not appear to intrinsically increase the risk of infection but can induce immune-related adverse effects requiring additional immunosuppression. Although CD4⁺ T-cell lymphopenia is associated with alefacept, no opportunistic infections have been observed. Progressive multifocal leukoencephalopathy (PML) may occur during therapy with natalizumab (anti-α4-integrin monoclonal antibody (mAb)) and efalizumab (anti-CD11a mAb), but no cases have been reported to date with vedolizumab (anti-α4β7 mAb). In patients at high risk for PML (positive anti-JC polyomavirus serology with serum antibody index >1.5 and duration of therapy ≥48 months), the benefit-risk ratio of continuing natalizumab should be carefully considered. Fingolimod induces profound peripheral blood lymphopenia and increases the risk of varicella zoster virus (VZV) infection. Prophylaxis with (val)acyclovir and VZV vaccination should be considered. Proteasome inhibitors also increase the risk of VZV infection, and antiviral prophylaxis with (val)acyclovir is recommended. Anti-Pneumocystis prophylaxis may be considered in myeloma multiple patients with additional risk factors (i.e. high-dose corticosteroids).

IMPLICATIONS

Clinicians should be aware of the risk of immune-related adverse effects and PML in patients receiving immune checkpoint and cell adhesion inhibitors respectively.

Reliability and Validity of a Danish Version of the Multiple Sclerosis Neuropsychological Screening Questionnaire

Background

More than half of all patients with multiple sclerosis (MS) acquire cognitive impairment as part of their disease progression. Because cognitive dysfunction adds substantially to disability and coping strategies, a cost-effective screening tool is needed for cognitive impairment. The Multiple Sclerosis Neuropsychological Screening Questionnaire (MSNQ) has previously shown good validity in American, Argentinean, and Dutch MS cohorts. We sought to test reliability and validity of a Danish translation of the MSNQ compared with formal neuropsychological testing, and measures of depression and disability, and to compare self-reported cognition with Symbol Digit Modalities Test (SDMT) results.

Methods

Of 126 patients with MS and their informants tested with the MSNQ, 77 also underwent formal neuropsychological testing. All patients were tested with the SDMT and assessed clinically using the Expanded Disability Status Scale and MS Impairment Scale.

Results

The test-retest reliability of the MSNQ-P was significant (R² = 0.79, P < .0001). R² of informants (MSNQ-I) and patients (MSNQ-P) was much lower (R² = 0.22, P < .0001). Compared with formal neuropsychological testing, the MSNQ-P and MSNQ-I performed poorly, with no correlation to individual neuropsychological tests, combined neuropsychological tests, or disability scores (Expanded Disability Status Scale and MS Impairment Scale). Depression/anxiety (Beck Depression Inventory) showed a weak linear relationship (R² = 0.25, P < .0001), suggesting that the MSNQ-P measures these items more than the cognitive abilities of the patients.

Conclusions

This study does not support use of the MSNQ as a sensitive or valid screening tool for cognitive impairment in Danish patients with MS.

JC Polyomavirus Attachment and Entry: Potential Sites for PML Therapeutics

PURPOSE OF REVIEW

JC polyomavirus (JCPyV) is a significant human pathogen that causes an asymptomatic infection in the kidney in the majority of the population. In immunosuppressed individuals, the virus can become reactivated and spread to the brain, causing the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML). There are currently limited treatment options for this fatal disease. Attachment to receptors and entry into host cells are the initiating events in JCPyV infection and therefore an attractive target for therapeutics to prevent or treat PML. This review provides the current understanding of JCPyV attachment and entry events and the potential therapeutics to target these areas.

RECENT FINDINGS

JCPyV attachment and entry to host cells is mediated by α2,6-linked lactoseries tetrasaccharide c (LSTc) and 5-hydroxytryptamine receptors (5-HT₂Rs), respectively, and subsequent trafficking to the endoplasmic reticulum is required for infection. Recently, vaccines, monoclonal antibodies, and small molecules have shown promise as anti-viral and PML therapies.

SUMMARY

This review summarizes our current understanding of JCPyV attachment, entry, and trafficking and the development of potential PML therapeutics that inhibit these critical steps in JCPyV infection.

Inflammatory Th17 Cells Express Integrin αvβ3 for Pathogenic Function

Interleukin-23 (IL-23) is required for inflammatory Th17 cell function in experimental autoimmune encephalomyelitis (EAE), and IL-23 blockade reduces the number of effector Th17 cells in the CNS. We report that pro-inflammatory Th17 cells express high integrin β3 that is IL-23 dependent. Integrin β3 was not upregulated on all activated T cells; rather, integrin β3 was upregulated along with its functional partner integrin αv on effector Th17 cells and "ex-Th17" cells, and αvβ3(hi) RORγt(+) cells expanded during EAE. Integrin αvβ3 inhibitors ameliorated clinical signs of EAE, and integrin β3 deficiency on CD4(+) T cells alone was sufficient to block EAE induction. Furthermore, integrin-β3-deficient Th17 cells, but not Th1 cells, were impaired in their ability to induce EAE. Integrin β3(-/-) T cells induced smaller demyelinated lesions and showed reduced spread and accumulation within the CNS, corresponding with impaired extracellular-matrix-mediated migration. Hence, integrin β3 is required for Th17 cell-mediated autoimmune CNS inflammation.

Monoclonal antibody therapies for the treatment of relapsing-remitting multiple sclerosis: differentiating mechanisms and clinical outcomes

Monoclonal antibody (mAb) therapies for relapsing-remitting multiple sclerosis (MS) target immune cells or other molecules involved in pathogenic pathways with extraordinary specificity. Natalizumab and alemtuzumab are the only two currently approved mAbs for the treatment of MS, having demonstrated significant reduction in clinical and magnetic resonance imaging disease activity and disability in clinical studies. Ocrelizumab and daclizumab are in the late stages of phase III trials, and several other mAbs are in the early stages of clinical evaluation. mAbs have distinct structural characteristics (e.g. chimeric, humanized, fully human) and unique targets (e.g. blocking interactions, induction of signal transduction by receptor binding, complement-dependent cytotoxicity, antibody-dependent cell-mediated cytotoxicity) conferring different mechanisms of action in MS. Because of these differences, mAbs for MS do not constitute a single treatment class; each must be considered individually when selecting appropriate therapy. Furthermore, in reviewing the data from clinical studies of mAbs, attention should be drawn to use of different comparators (e.g. placebo or interferon β-1a) and study designs. Each mAb treatment has a unique administration schedule. In the decision to select the appropriate treatment for each individual MS patient, careful review of the benefits relative to risks of mAbs is balanced against the risk of development of MS-associated disability.

Oligomerization of neutral peptides derived from the JC virus agnoprotein through a cysteine residue

The JC virus is the causative agent of progressive multifocal leukoencephalopathy. The viral genome encodes a multifunctional protein known as agnoprotein which is essential for viral proliferation and reported to possess the oligomerization sequence. However, the structural relationship with the oligomerization is unclear. We synthesized 23 amino acid residue neutral peptides derived from the JC virus agnoprotein, Lys22 to Asp44. The secondary structures of these peptides were β-sheet in aqueous buffer that converted to a helical structure in a hydrophobic environment. These peptides interestingly formed dimers and oligomers under oxidizing conditions. The oligomerization was facilitated by addition of bismaleimides and the derivative without thiol group did not form such oligomers. These results suggest that Agno(22-44) could be transmembrane and one disulfide bond between Cys40 triggers the oligomerization.

JC Virus PCR Detection Is Not Infallible: A Fulminant Case of Progressive Multifocal Leukoencephalopathy with False-Negative Cerebrospinal Fluid Studies despite Progressive Clinical Course and Radiological Findings

We describe a case with a false-negative PCR-based analysis for JC virus in cerebrospinal fluid (CSF) in a patient with clinical and radiological findings suggestive of progressive multifocal leukoencephalopathy (PML) who was on chronic immunosuppressive therapy for rheumatoid arthritis. Our patient developed rapidly progressive global decline with clinical and radiographic findings suggestive of PML, but JC virus PCR in CSF was negative. The patient passed away 3 months from the onset of her neurological symptoms. Autopsy confirmed the diagnosis of PML with presence of JC-polyoma virus by immunohistochemical staining. This case highlights the potential of false-negative JC virus PCR in CSF when radiographic and clinical features are suggestive of “possible PML.” We review the plausible causes of potential false-negative CSF results and suggest that when the clinical presentation is suspicious for PML repeat CSF analysis utilizing ultrasensitive PCR assay and subsequent brain biopsy should be considered if CSF remains negative. Additionally, appropriate exclusion of other neurologic conditions is essential.

No association between Birt-Hogg-Dubé syndrome skin fibrofolliculomas and the first 10 described human polyomaviruses or human papillomaviruses

The rare autosomal dominant condition Birt-Hogg-Dubé syndrome (BHD) is attributed to mutations on chromosome 17 in the folliculin (FLCN) gene, but not always diagnosed due to lack of, or a variety of symptoms such as fibrofolliculomas, lung cystic lesions, spontaneous pneumothorax and renal cancer. We hypothesized that the lack of or variability in symptoms could be due to BHD patients potentially being abnormally susceptible to infections with human papillomavirus (HPV) or human polyomavirus (HPyV), which can be associated with skin lesions or latency in the kidneys. Seven fibrofolliculoma skin lesions, one renal cancer and one lung cyst from nine patients with BHD treated at the Karolinska University Hospital were therefore analyzed for cutaneous and mucosal HPV types and 10 HPyVs by bead based multiplex assays or by PCR. All samples were negative for viral DNA. In conclusion, the data suggest that HPV and HPyVs do not contribute to BHD pathology.

JC polyomavirus attachment, entry, and trafficking: unlocking the keys to a fatal infection

The human JC polyomavirus (JCPyV) causes a lifelong persistent infection in the reno-urinary tract in the majority of the adult population worldwide. In healthy individuals, infection is asymptomatic, while in immunocompromised individuals, the virus can spread to the central nervous system and cause a fatal demyelinating disease known as progressive multifocal leukoencephalopathy (PML). There are currently very few treatment options for this rapidly progressing and devastating disease. Understanding the basic biology of JCPyV-host cell interactions is critical for the development of therapeutic strategies to prevent or treat PML. Research in our laboratory has focused on gaining a detailed mechanistic understanding of the initial steps in the JCPyV life cycle in order to define how JCPyV selectively targets cells in the kidney and brain. JCPyV requires sialic acids to attach to host cells and initiate infection, and JCPyV demonstrates specificity for the oligosaccharide lactoseries tetrasaccharide c (LSTc) with an α2,6-linked sialic acid. Following viral attachment, JCPyV entry is facilitated by the 5-hydroxytryptamine (5-HT)2 family of serotonin receptors via clathrin-dependent endocytosis. JCPyV then undergoes retrograde transport to the endoplasmic reticulum (ER) where viral disassembly begins. A novel retrograde transport inhibitor termed Retro-2(cycl) prevents trafficking of JCPyV to the ER and inhibits both initial virus infection and infectious spread in cell culture. Understanding the molecular mechanisms by which JCPyV establishes infection will open up new avenues for the prevention or treatment of virus-induced disease.

Gallic acid-based small-molecule inhibitors of JC and BK polyomaviral infection

JCPyV and BKPyV are common human polyomaviruses that cause lifelong asymptomatic persistent infections in their hosts. In immunosuppressed individuals, increased replication of JCPyV and BKPyV cause significant disease. JCPyV causes a fatal and rapidly progressing demyelinating disease known as progressive multifocal leukoencephalopathy. BKPyV causes hemorrhagic cystitis and polyomavirus associated nephropathy in bone marrow transplant recipients and in renal transplant recipients respectively. There are no specific anti-viral therapies to treat polyomavirus induced diseases. Based on detailed studies of the structures of these viruses bound to their receptors we screened several compounds that possessed similar chemical space as sialic acid for their ability to bind the virus. Positive hits in the assay were restricted to gallic acid based compounds that mimic the viruses known cellular glycan receptors. Pre-treatment of virions with these inhibitors reduced virus infection in cell culture and as such may form the basis for the development of virion specific antagonists to treat these infections.

Gallic acid-based small-molecule inhibitors of JC and BK polyomaviral infection

JCPyV and BKPyV are common human polyomaviruses that cause lifelong asymptomatic persistent infections in their hosts. In immunosuppressed individuals, increased replication of JCPyV and BKPyV cause significant disease. JCPyV causes a fatal and rapidly progressing demyelinating disease known as progressive multifocal leukoencephalopathy. BKPyV causes hemorrhagic cystitis and polyomavirus associated nephropathy in bone marrow transplant recipients and in renal transplant recipients respectively. There are no specific anti-viral therapies to treat polyomavirus induced diseases. Based on detailed studies of the structures of these viruses bound to their receptors we screened several compounds that possessed similar chemical space as sialic acid for their ability to bind the virus. Positive hits in the assay were restricted to gallic acid based compounds that mimic the viruses known cellular glycan receptors. Pre-treatment of virions with these inhibitors reduced virus infection in cell culture and as such may form the basis for the development of virion specific antagonists to treat these infections.

Vedolizumab for the treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease of the large intestine that often develops in the young. A few new treatment options have become available in the past decade, but management of a large proportion of patients still remains challenging because of side effects, unresponsiveness and cost. A novel strategy targeting trafficking of immune cells to the sites of inflammation involves reducing expression or binding of adhesion molecules to integrins. Natalizumab was the first therapeutic antibody blocking infiltration of leukocytes, but because of lack of selectivity to the gut and associated risk of progressive multifocal leukoencephalopathy, it will probably never be tested in ulcerative colitis. In this article we discuss molecules that block leukocyte trafficking to inflamed bowel that have been tested in ulcerative colitis. Because of favourable efficacy and safety data, we will review the development, pharmacology and clinical data of vedolizumab, a gut-selective α4β7 antibody, in depth.

Management of disease-modifying treatments in neurological autoimmune diseases of the central nervous system

The therapeutic armamentarium for autoimmune diseases of the central nervous system, specifically multiple sclerosis and neuromyelitis optica, is steadily increasing, with a large spectrum of immunomodulatory and immunosuppressive agents targeting different mechanisms of the immune system. However, increasingly efficacious treatment options also entail higher potential for severe adverse drug reactions. Especially in cases failing first-line treatment, thorough evaluation of the risk-benefit profile of treatment alternatives is necessary. This argues for the need of algorithms to identify patients more likely to benefit from a specific treatment. Moreover, paradigms to stratify the risk for severe adverse drug reactions need to be established. In addition to clinical/paraclinical measures, biomarkers may aid in individualized risk-benefit assessment. A recent example is the routine testing for anti-John Cunningham virus antibodies in natalizumab-treated multiple sclerosis patients to assess the risk for the development of progressive multi-focal leucoencephalopathy. Refined algorithms for individualized risk assessment may also facilitate early initiation of induction treatment schemes in patient groups with high disease activity rather than classical escalation concepts. In this review, we will discuss approaches for individiualized risk-benefit assessment both for newly introduced agents as well as medications with established side-effect profiles. In addition to clinical parameters, we will also focus on biomarkers that may assist in patient selection.

Pharmacological inhibition of the chemokine receptor CX3CR1 attenuates disease in a chronic-relapsing rat model for multiple sclerosis

One hallmark of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) is infiltration of leukocytes into the CNS, where chemokines and their receptors play a major mediatory role. CX3CR1 is a chemokine receptor involved in leukocyte adhesion and migration and hence a mediator of immune defense reactions. The role of CX3CR1 in MS and EAE pathogenesis however remains to be fully assessed. Here, we demonstrate CX3CR1 mRNA expression on inflammatory cells within active plaque areas in MS brain autopsies. To test whether blocking CNS infiltration of peripheral leukocytes expressing CX3CR1 would be a suitable treatment strategy for MS, we developed a selective, high-affinity inhibitor of CX3CR1 (AZD8797). The compound is active outside the CNS and AZD8797 treatment in Dark Agouti rats with myelin oligodendrocyte glycoprotein-induced EAE resulted in reduced paralysis, CNS pathology, and incidence of relapses. The compound is effective when starting treatment before onset, as well as after the acute phase. This treatment strategy is mechanistically similar to, but more restricted than, current very late antigen-4-directed approaches that have significant side effects. We suggest that blocking CX3CR1 on leukocytes outside the CNS could be an alternative approach to treat MS.

Prophylactic antiepileptic treatment reduces seizure frequency in natalizumab-associated progressive multifocal leukoencephalopathy

OBJECTIVE

Little is known about seizures in natalizumab-associated progressive multifocal leukoencephalopathy (NAT-PML).

METHODS

A review of clinical records of 15 NAT-PML patients with multiple sclerosis (MS) treated at a German university hospital.

RESULTS

Some 53% (8/15) of our patients developed seizures with often multiple semiologies (seven grand mal, three simple partial motor and two psychomotor seizures). Series of seizures or status epilepticus occurred in seven of these eight. Seizure onset was on average 61 days after onset of NAT-PML and was associated with immune reconstitution inflammatory syndrome (IRIS) in five of eight patients. After having observed severe seizures during NAT-PML in seven of our first nine patients, we started preventive antiepileptic treatment (PAT) with levetiracetam (1000-1750 mg/day). Patient subgroups analyzed for seizures and PAT did not differ in baseline characteristics. Only one of six patients, who received PAT, had a seizure compared with seven of nine patients without PAT (2-tailed Fisher's exact test, p = 0.04).

CONCLUSIONS

Although the small sample size and retrospective nature of the study are limitations, we propose to treat NAT-PML patients with PAT early after diagnosis, as seizures seem to be common and severe in NAT-PML.

New and emerging immune-targeted drugs for the treatment of multiple sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease with a major inflammatory component that constitutes the most common progressive and disabling neurological condition in young adults. Injectable immunomodulatory medicines such as interferon drugs and glatiramer acetate have dominated the MS market for over the past two decades but this situation is set to change. This is because of: (i) patent expirations, (ii) the introduction of natalizumab, which targets the interaction between leukocytes and the blood-CNS barrier, (iii) the launch of three oral immunomodulatory drugs (fingolimod, dimethyl fumarate and teriflunomide), with another (laquinimod) under regulatory review and (iv) a number of immunomodulatory monoclonal antibodies (alemtuzumab, daclizumab and ocrelizumab) about to enter the market. Current and emerging medicines are reviewed and their impact on people with MS considered.

Impact of JC virus antibody testing in patients with Crohn's disease with loss of response to infliximab: a Markov model

BACKGROUND

The optimal treatment strategy for patients with Crohn's disease who have loss of response to the anti-tumor necrosis factor α medication infliximab is uncertain. Natalizumab has an alternative mechanism of action, but its use has been limited by the risk of progressive multifocal leukoencephalopathy. In this study, we performed a decision analysis assessing the impact of JC virus (JCV) antibody testing and natalizumab utilization for loss of response to infliximab.

METHODS

We constructed a Markov model to assess the difference between unscreened natalizumab use (option 1), JCV antibody testing with natalizumab when appropriate (option 2), and second anti-tumor necrosis factor α use (option 3). The base case was a 35-year-old man with severe Crohn's disease with loss of response to infliximab. The time horizon was 3 years. Results are reported in quality-adjusted life years (QALYs). Deterministic and probabilistic analyses were conducted. Markov analysis using a cohort of 5000 individuals was performed. The impact of JCV antibody status on outcomes in this model was assessed.

RESULTS

Option 2 was the preferred strategy (2.0880 QALYs), followed by option 1 (2.0875 QALYs) and option 3 (2.0808 QALYs). Patients in option 2 required fewer surgeries compared with option 3. Previous JCV infection was associated with reduced QALYs with all options that allowed for natalizumab use.

CONCLUSIONS

JCV antibody testing and subsequent treatment selection yield improved outcomes over natalizumab without testing or using only a second anti-tumor necrosis factor α in all patients.

Overview of experimental models of the blood-brain barrier in CNS drug discovery

The blood-brain barrier (BBB) is a physical and metabolic entity that isolates the brain from the systemic circulation. The barrier consists of tight junctions between endothelial cells that contain egress transporters and catabolic enzymes. To cross the BBB, a drug must possess the appropriate physicochemical properties to achieve a sufficient time-concentration profile in brain interstitial fluid (ISF). In this overview, we review techniques to measure BBB permeation, which is evidenced by the free concentration of compound in brain ISF over time. We consider a number of measurement techniques, including in vivo microdialysis and brain receptor occupancy following perfusion. Consideration is also given to the endothelial and nonendothelial cell systems used to assess both the BBB permeation of a test compound and its interactions with egress transporters, and computer models employed for predicting passive permeation and the probability of interactions with BBB transporters.

Natalizumab-related progressive multifocal leukoencephalopathy in Greece

BACKGROUND & OBJECTIVES

Progressive multifocal leukoencephalopathy (PML) may complicate natalizumab treatment in multiple sclerosis patients. We sought to characterize the clinical and laboratory features of natalizumab-related PML (NR-PML) cases from Greece.

METHODS

Pharmaceutical industry, national drug authorities and all neurology departments within the Greek territory were asked to provide data for cases of NR-PML until October 2012. Collected cases were classified according to their level of diagnostic certainty using the five-level system introduced by Mentzer et al. (2012).

RESULTS

Thirteen NR-PML cases were identified by the neurology departments. Data were provided for only 9 cases. PML manifestations appeared after a median number of 40 (21-52) natalizumab infusions. All but two patients were treated with plasma exchange and some were treated adjunctively with mirtazapine while the others were treated with mefloquine. IRIS developed in 6 cases after a median time of 6 (2-10) weeks from PML presentation and were treated with different regimens of corticosteroids. PML was fatal in 3 cases. The median EDSS after a median follow-up time of 12 (8-23) months in the surviving cases was 4.75 (2-8.5).

CONCLUSIONS

Outcomes for collected NR-PML cases varied from death to returning to baseline. Close surveillance is essential for early diagnosis and treatment of NR-PML patients.

Immune cells after prolonged Natalizumab therapy: implications for effectiveness and safety

BACKGROUND

Previous studies on Natalizumab (NAT) have shown increased circulation of most white blood cells (WBC) in multiple sclerosis (MS) patients shortly after its introduction.

AIM

To describe peripheral immune cell phenotypes after more than 2 years of continuous NAT therapy and test for associations with clinical response to therapy.

METHODS

Peripheral immune cell subsets were analyzed in 44 NAT-MS patients receiving NAT for over 24 months, and in 22 NAT-free control-MS patients.

RESULTS

NAT-MS patients displayed significantly higher numbers of all WBC when compared with controls. B lymphocytes exhibited a more pronounced increase when compared with CD4+, CD8+ and NK T-cells (P = 0.011). CD4/CD8 ratio was significantly decreased in NAT-MS patients (P = 0.018) and showed no correlation with the number of NAT doses. The reduced CD4/CD8 ratio was attributable to the 'EDSS improvement' group only, irrespective of age, sex and disease severity.

CONCLUSIONS

The study suggests that there is no desensitization effect after prolonged NAT exposure. A reduced CD4/CD8 ratio was associated with long-term response to therapy; thus, those patients who most benefitted from the drug might be at greater risk for opportunistic infections like progressive multifocal leucoencephalopathy (PML). We provide implications for future research for the CD4/CD8 ratio as a possible contributor to the recently developed risk stratification scheme for PML.

Progressive multifocal leukoencephalopathy-associated mutations in the JC polyomavirus capsid disrupt lactoseries tetrasaccharide c binding

The human JC polyomavirus (JCPyV) is the causative agent of the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML). The Mad-1 prototype strain of JCPyV uses the glycan lactoseries tetrasaccharide c (LSTc) and serotonin receptor 5-HT_2A to attach to and enter into host cells, respectively. Specific residues in the viral capsid protein VP1 are responsible for direct interactions with the α2,6-linked sialic acid of LSTc. Viral isolates from individuals with PML often contain mutations in the sialic acid-binding pocket of VP1 that are hypothesized to arise from positive selection. We reconstituted these mutations in the Mad-1 strain of JCPyV and found that they were not capable of growth. The mutations were then introduced into recombinant VP1 and reconstituted as pentamers in order to conduct binding studies and structural analyses. VP1 pentamers carrying PML-associated mutations were not capable of binding to permissive cells. High-resolution structure determination revealed that these pentamers are well folded but no longer bind to LSTc due to steric clashes in the sialic acid-binding site. Reconstitution of the mutations into JCPyV pseudoviruses allowed us to directly quantify the infectivity of the mutants in several cell lines. The JCPyV pseudoviruses with PML-associated mutations were not infectious, nor were they able to engage sialic acid as measured by hemagglutination of human red blood cells. These results demonstrate that viruses from PML patients with single point mutations in VP1 disrupt binding to sialic acid motifs and render these viruses noninfectious.

Infection with human JC polyomavirus (JCPyV) is common and asymptomatic in healthy individuals, but during immunosuppression, JCPyV can spread from the kidney to the central nervous system (CNS) and cause a fatal, demyelinating disease, progressive multifocal leukoencephalopathy (PML). Individuals infected with HIV, those who have AIDS, or those receiving immunomodulatory therapies for autoimmune diseases are at serious risk for PML. Recent reports have demonstrated that viral isolates from PML patients often have distinct changes within the major capsid protein. Our structural-functional approach highlights that these mutations result in abolished engagement of the carbohydrate receptor motif LSTc that is necessary for infection. Viruses with PML-associated mutations are not infectious in glial cells, suggesting that they may play an alternative role in PML pathogenesis.

Consensus guidelines for the diagnosis and treatment of multiple sclerosis

The diagnosis of multiple sclerosis (MS) is dependent on the presence of clinical and paraclinical evidence demonstrating dissemination of central nervous system lesions in both space and time, as well as the exclusion of other disorders. Diagnostic criteria were originally promulgated in 1965 by the Schumacher committee and modified subsequently by the Poser committee to include paraclinical evidence. The most recent criteria are the 2010 modifications of the 2001 McDonald criteria, which are focused on making an earlier diagnosis of MS. This article provides guidelines, derived from clinical experience as well as evidence-based medicine, for the diagnosis and management of MS with special emphasis on practices in the Middle East.

What went wrong? The flawed concept of cerebrospinal venous insufficiency

In 2006, Zamboni reintroduced the concept that chronic impaired venous outflow of the central nervous system is associated with multiple sclerosis (MS), coining the term of chronic cerebrospinal venous insufficiency ('CCSVI'). The diagnosis of 'CCSVI' is based on sonographic criteria, which he found exclusively fulfilled in MS. The concept proposes that chronic venous outflow failure is associated with venous reflux and congestion and leads to iron deposition, thereby inducing neuroinflammation and degeneration. The revival of this concept has generated major interest in media and patient groups, mainly driven by the hope that endovascular treatment of 'CCSVI' could alleviate MS. Many investigators tried to replicate Zamboni's results with duplex sonography, magnetic resonance imaging, and catheter angiography. The data obtained here do generally not support the 'CCSVI' concept. Moreover, there are no methodologically adequate studies to prove or disprove beneficial effects of endovascular treatment in MS. This review not only gives a comprehensive overview of the methodological flaws and pathophysiologic implausibility of the 'CCSVI' concept, but also summarizes the multimodality diagnostic validation studies and open-label trials of endovascular treatment. In our view, there is currently no basis to diagnose or treat 'CCSVI' in the care of MS patients, outside of the setting of scientific research.

Progressive multifocal leukoencephalopathy and idiopathic CD4 lymphocytopenia

Idiopathic CD4 lymphocytopenia (ICL) is a syndrome described in patients with low counts of CD4 cells and no other causes for immunosuppression. A few cases of progressive multifocal leukoencephalopathy (PML) have been described in association with this entity. There is no effective treatment for any of them, and the clinical course and outcome are unpredictable. We report on a case of ICL with PML and review the literature, trying to identify the clinical features and the prognosis clues associated to these entities together. A 72-year-old man presented with acute onset gait instability that progressed to a severe cerebellar syndrome with cognitive decline. A cranial MRI showed findings consistent with PML, this diagnosis being confirmed by CSF analyses. Absolute number of CD4+ was 242 cells/μL. An extensive work-up including HIV tests was negative. Ten cases of PML and ICL have previously been reported. Factors contributing to the different outcomes are unknown. Although an effective treatment does not exist for PML, it has been recently demonstrated in vitro that several 5HT2A-receptor antagonists block the JC virus infection. Our patient greatly improved and remains stable 34 months after onset; we describe the potential role of mirtazapine in the treatment of PML.

Epigallocatechin-3-gallate: a useful, effective and safe clinical approach for targeted prevention and individualised treatment of neurological diseases?

Neurodegenerative disorders show an increasing prevalence in a number of highly developed countries. Often, these diseases require life-long treatment mostly with drugs which are costly and mostly accompanied by more or less serious side-effects. Their heterogeneous manifestation, severity and outcome pose the need for individualised treatment options. There is an intensive search for new strategies not only for treating but also for preventing these diseases. Green tea and green tea extracts seem to be such a promising and safe alternative. However, data regarding the beneficial effects and possible underlying mechanism, specifically in clinical trials, are rare and rather controversial or non-conclusive. This review outlines the existing evidence from preclinical studies (cell and tissue cultures and animal models) and clinical trials regarding preventive and therapeutic effects of epigallcatechin-3-gallate in neurodegenerative diseases and considers antioxidative vs. pro-oxidative properties of the tea catechin important for dosage recommendations.

Masquerades of acquired demyelination in children: experiences of a national demyelinating disease program

The diagnosis of acquired demyelinating syndromes of the central nervous system in children requires exclusion of other acute central nervous system disorders. In a 23-site national demyelinating disease study, standardized clinical, laboratory, and magnetic resonance imaging (MRI) data were obtained prospectively from onset, and serially at 3, 6, and 12 months and annually. Twenty of 332 (6%) participants (mean [SD] age, 10.21 [4.32] years; 12 (60%) female) were ultimately diagnosed with vascular disorders (primary or secondary central nervous system vasculitis, vasculopathy, stroke, or migraine, n = 11 children), central nervous system malignancy (n = 3), mitochondrial disease (n = 2), or central nervous system symptoms in the accompaniment of confirmed infection (n = 4). Red flags that may serve to distinguish disorders in the differential of acquired demyelination are described.

Human polyomaviruses in disease and cancer

Today the human polyomavirus (HPyV) family consists of 10 members, BK virus (BKV) and JC virus (JCV) isolated 40 years ago and the more recently identified KI virus (KIPyV), WU virus (WUPyV), Merkel cell polyomavirus (MCPyV), HPyV6, HPyV7, trichodysplasia spinulosa virus (TSPyV), HPyV9 and MWPyV. Serological studies suggest that HPyVs subclinically infect the general population with rates ranging from 35% to 90%. However, significant disease is only observed in patients with impaired immune functions. Thus, BKV has been linked to hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplantation and PyV-associated nephropathy (PyVAN) after kidney transplantation; JCV to progressive multifocal leukoencephalopathy (PML) in HIV-AIDS, hematological diseases and in autoimmune diseases treated with certain lymphocyte-specific antibodies. KIPyV and WUPyV have been found in the respiratory tract, HPyV6 and 7 in the skin, and HPyV9 in serum and skin, and MWPyV in stools and skin, but so far none of these PyVs have been linked to any disease. TSPyV, on the other hand, was identified in trichodysplasia spinulosa, a rare skin disease characterized by virus-induced lytic as well as proliferative tumor-like features that is observed in immune-suppressed transplant patients. In contrast to all the other HPyVs so far, MCPyV is unique in its association with a cancer, Merkel cell carcinoma, which is a rare skin cancer arising in the elderly and chronically immunosuppressed individuals. The discovery of the new HPyVs has revived interest in the Polyomaviridae and their association to human disease and cancer. In this review, we summarize knowledge about this expanding family of human pathogens.

Leukocyte trafficking mechanisms in epilepsy

Epilepsy is a chronic disorder that affects 1% of the world population and is characterized by chronically reoccurring seizures. Seizures are initiated by abnormal excessive or synchronous neuronal activity in the brain. Epilepsy requires life long anti-convulsant therapy and current therapies for epilepsy selectively target neuronal activity. In the last decade, cytokines and vascular alterations have been discussed in relation to the pathogenesis of epilepsy, suggesting a potential role for inflammation mechanisms in seizure induction. More recently, it has been shown that leukocyte trafficking plays a key role in seizure generation, and that anti-leukocyte adhesion therapy has therapeutic and preventative effects in an experimental model of human epilepsy. These results were supported by evidence in humans showing that leukocytes accumulate in the brain parenchyma of patients with different types of epilepsy. Finally, recent clinical observations suggest that therapies able to interfere with leukocyte trafficking may have a therapeutic effect in epilepsy. The emerging role for leukocytes and leukocyte adhesion mechanisms in seizure generation provides insight into the mechanisms of brain damage and may contribute to the development of novel therapeutic strategies in epilepsy.

Multiple sclerosis and the blood-central nervous system barrier

The central nervous system (CNS) is isolated from the blood system by a physical barrier that contains efflux transporters and catabolic enzymes. This blood-CNS barrier (BCNSB) plays a pivotal role in the pathophysiology of multiple sclerosis (MS). It binds and anchors activated leukocytes to permit their movement across the BCNSB and into the CNS. Once there, these immune cells target particular self-epitopes and initiate a cascade of neuroinflammation, which leads to the breakdown of the BCNSB and the formation of perivascular plaques, one of the hallmarks of MS. Immunomodulatory drugs for MS are either biologics or small molecules, with only the latter having the capacity to cross the BCNSB and thus have a propensity to cause CNS side effects. However, BCNSB penetration is a desirable feature of MS drugs that have molecular targets within the CNS. These are nabiximols and dalfampridine, which target cannabinoid receptors and potassium channels, respectively. Vascular cell adhesion molecule-1, present on endothelial cells of the BCNSB, also serves as a drug discovery target since it interacts with α4-β1-integrin on leucocytes. The MS drug natalizumab, a humanized monoclonal antibody against α4-β1-integrin, blocks this interaction and thus reduces the movement of immune cells into the CNS. This paper further elaborates on the role of the BCNSB in the pathophysiology and pharmacotherapy of MS.

Emerging roles of endothelial cells in multiple sclerosis pathophysiology and therapy

Although multiple sclerosis (MS) has traditionally been viewed and researched as an immune-mediated demyelinating and neurodegenerative disease of the human central nervous system (CNS), its highly complex pathogenesis clearly includes a significant vascular inflammatory component and many therapeutic approaches achieve benefit by direct or indirect effects on cerebrovascular endothelial cells. Cerebral endothelial cells create and separate the compartments of the peripheral circulation and CNS creating the blood-brain barrier (BBB), a selectively permeable boundary layer between these spaces. Interactions between activated leukocytes and cerebral endothelium play essential roles in mediating their trans-BBB diapedesis during normal immune surveillance and during pathogenesis of neuroinflammatory diseases like MS. Extravasation of activated and committed leukocytes from the peripheral circulation through the endothelial layer of the BBB into the CNS milieu is the most fundamental step in formation of MS lesions. During MS pathogenesis, once the activated leukocytes enter the CNS environment, they propagate a massive wave of destruction which culminates in the loss of both myelin/oligodendrocyte complex and neurodegeneration. Multiple clinical and basic scientific observations support endothelial cell 'stress' and apoptosis as a hallmark characteristic of MS. The manipulation of the endothelial biology aiming to block trans-endothelial migration of activated immune cells into the CNS is a potent form of treatment for MS achieving significant reductions in disease activity and new lesion formation. In particular, endothelial microparticles are now well-recognized as important biomarkers and mediators of this type of stress. In this review, we discuss recent findings and new advances in our knowledge regarding leukocyte migration through the endothelial frontier of the BBB and how this can be exploited toward treating MS patients.

Pharmacotherapeuetic Options for the Treatment of Multiple Sclerosis

Multiple sclerosis is the most common progressive and disabling neurological condition in young adults. Neuro-inflammation is an early and persistent change and forms the basis of most pharmacotherapy for this disease. Immunomodulatory drugs are mainly biologies (β-interferons, a four amino acid peptide, and a monoclonal antibody to a cell adhesion molecule on the blood-CNS barrier) that either attenuate the inflammatory response or block the movement of immune cells into the CNS. They reduce the rate of relapse, but have little or no effect on the progression of disability. The market landscape for MS drugs is in the midst of major change because the patent life of many of these medicines will soon expire, which will lead to the emergence of biosimilars. In addition, new small molecule immunomodulatory and palliative drugs have entered the market, with more in the pipeline; a number of monoclonal antibodies and other immunomodulatory drugs are also in clinical development.