Decrease in the numbers of dendritic cells and CD4+ T cells in cerebral perivascular spaces due to natalizumab

[Biobanking in clinical trials involving multiple sclerosis patients]

Investigation of multiple sclerosis (MS) pathogenesis requires sophisticated analytical tools of precision medicine, such as omics research, which include genomics, microbiomics and metabolomics (proteomics, lipidomics and glycomics). Such sensitive methods are based on careful preanalytical work with biomaterials to maintain quality and obtain objective results. Implementation of biobanking as a universal method for working with biomaterials will help to standardize the stages of research, compare different scientific team's results. Collaboration of MS researchers with large biobanks can also help to conduct multicenter and long-term prospective studies, to include a wide number of patients. In this article, we analyze the experience of biobanking practice technologies in studies of MS patients and share the experience of partnership between the Center for MS of the Tomsk Region and the Bank of Biological Material of the Siberian State Medical University.

Dendritic Cells as a Nexus for the Development of Multiple Sclerosis and Models of Disease

Multiple sclerosis (MS) results from an autoimmune attack on the central nervous system (CNS). Dysregulated immune cells invade the CNS, causing demyelination, neuronal and axonal damage, and subsequent neurological disorders. Although antigen-specific T cells mediate the immunopathology of MS, innate myeloid cells have essential contributions to CNS tissue damage. Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that promote inflammation and modulate adaptive immune responses. This review focuses on DCs as critical components of CNS inflammation. Here, evidence from studies is summarized with animal models of MS and MS patients that support the critical role of DCs in orchestrating CNS inflammation.

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.

People with Primary Progressive Multiple Sclerosis Have a Lower Number of Central Memory T Cells and HLA-DR+ Tregs

The importance of circulating immune cells to primary progressive multiple sclerosis (PPMS) pathophysiology is still controversial because most immunotherapies were shown to be ineffective in treating people with PPMS (pwPPMS). Yet, although controversial, data exist describing peripheral immune system alterations in pwPPMS. This study aims to investigate which alterations might be present in pwPPMS free of disease-modifying drugs (DMD) in comparison to age- and sex-matched healthy controls. A multicentric cross-sectional study was performed using 23 pwPPMS and 23 healthy controls. The phenotype of conventional CD4+ and CD8+ T cells, regulatory T cells (Tregs), B cells, natural killer (NK) T cells and NK cells was assessed. Lower numbers of central memory CD4+ and CD8+ T cells and activated HLA-DR+ Tregs were observed in pwPPMS. Regarding NK and NKT cells, pwPPMS presented higher percentages of CD56dimCD57+ NK cells expressing NKp46 and of NKT cells expressing KIR2DL2/3 and NKp30. Higher disease severity scores and an increasing time since diagnosis was correlated with lower numbers of inhibitory NK cells subsets. Our findings contribute to reinforcing the hypotheses that alterations in peripheral immune cells are present in pwPPMS and that changes in NK cell populations are the strongest correlate of disease severity.

Impact of disease-modifying therapy on dendritic cells and exploring their immunotherapeutic potential in multiple sclerosis

Dendritic cells (DCs) are the most potent professional antigen-presenting cells (APCs), which play a pivotal role in inducing either inflammatory or tolerogenic response based on their subtypes and environmental signals. Emerging evidence indicates that DCs are critical for initiation and progression of autoimmune diseases, including multiple sclerosis (MS). Current disease-modifying therapies (DMT) for MS can significantly affect DCs' functions. However, the study on the impact of DMT on DCs is rare, unlike T and B lymphocytes that are the most commonly discussed targets of these therapies. Induction of tolerogenic DCs (tolDCs) with powerful therapeutic potential has been well-established to combat autoimmune responses in laboratory models and early clinical trials. In contrast to in vitro tolDC induction, in vivo elicitation by specifically targeting multiple cell-surface receptors has shown greater promise with more advantages. Here, we summarize the role of DCs in governing immune tolerance and in the process of initiating and perpetuating MS as well as the effects of current DMT drugs on DCs. We then highlight the most promising cell-surface receptors expressed on DCs currently being explored as the viable pharmacological targets through antigen delivery to generate tolDCs in vivo.

Management of inflammatory bowel disease beyond tumor necrosis factor inhibitors: novel biologics and small-molecule drugs

The incidence and prevalence of inflammatory bowel disease (IBD), comprising Crohn's disease and ulcerative colitis, have increased in Asia and developing countries. In the past two decades, anti-tumor necrosis factor (TNF) agents have revolutionized the treatment of IBD, in part by decreasing the rates of complications and surgery. Although anti-TNF agents have changed the course of IBD, there are unmet needs in terms of primary and secondary non-responses and side effects such as infections and malignancies. Novel biologics and small-molecule drugs have been developed for IBD, and the medical treatment options have improved. These drugs include sphingosine-1-phosphate receptor modulators and anti-integrins to block immune cell migration, and cytokine and Janus kinase inhibitors to block immune cell communications. In this review, we discuss the approved novel biologics and small-molecule drugs, including several of those in the late stages of development, for the treatment of IBD.

Neuroprotective Potential of Dendritic Cells and Sirtuins in Multiple Sclerosis

Myeloid cells, including parenchymal microglia, perivascular and meningeal macrophages, and dendritic cells (DCs), are present in the central nervous system (CNS) and establish an intricate relationship with other cells, playing a crucial role both in health and in neurological diseases. In this context, DCs are critical to orchestrating the immune response linking the innate and adaptive immune systems. Under steady-state conditions, DCs patrol the CNS, sampling their local environment and acting as sentinels. During neuroinflammation, the resulting activation of DCs is a critical step that drives the inflammatory response or the resolution of inflammation with the participation of different cell types of the immune system (macrophages, mast cells, T and B lymphocytes), resident cells of the CNS and soluble factors. Although the importance of DCs is clearly recognized, their exact function in CNS disease is still debated. In this review, we will discuss modern concepts of DC biology in steady-state and during autoimmune neuroinflammation. Here, we will also address some key aspects involving DCs in CNS patrolling, highlighting the neuroprotective nature of DCs and emphasizing their therapeutic potential for the treatment of neurological conditions. Recently, inhibition of the NAD⁺-dependent deac(et)ylase sirtuin 6 was demonstrated to delay the onset of experimental autoimmune encephalomyelitis, by dampening DC trafficking towards inflamed LNs. Thus, a special focus will be dedicated to sirtuins’ role in DCs functions.

Efficacy of Disease Modifying Therapies in Progressive MS and How Immune Senescence May Explain Their Failure

The advent of disease modifying therapies (DMT) in the past two decades has been the cornerstone of successful clinical management of multiple sclerosis (MS). Despite the great strides made in reducing the relapse frequency and occurrence of new signal changes on neuroimaging in patients with relapsing remitting MS (RRMS) by approved DMT, it has been challenging to demonstrate their effectiveness in non-active secondary progressive MS (SPMS) and primary progressive MS (PPMS) disease phenotypes. The dichotomy of DMT effectiveness between RRMS and progressive MS informs on distinct pathogeneses of the different MS phenotypes. Conversely, factors that render patients with progressive MS resistant to therapy are not understood. Thus far, age has emerged as the main correlate of the transition from RRMS to SPMS. Whether it is aging and age-related factors or the underlying immune senescence that qualitatively alter immune responses as the disease transitions to SPMS, that diminish DMT effectiveness, or both, is currently not known. Here, we will discuss the role of immune senescence on different arms of the immune system, and how it may explain relative DMT resistance.

The sequential natalizumab – alemtuzumab therapy in patients with relapsing forms of multiple sclerosis (SUPPRESS) trial – Part I: Rationale and objectives

Background

Natalizumab is a recombinant humanized monoclonal antibody (mAb) against α4-integrin that is approved for relapsing forms of multiple sclerosis (MS). Natalizumab is associated with an increased risk of developing progressive multifocal leukoencephalopathy (PML), and with disease reactivation after cessation of treatment that is likely mediated by an accumulation of pro-inflammatory lymphocytes in the blood during therapy. Alemtuzumab is a mAb against CD52 that reduces the number of peripheral lymphocytes.

Rationale

To determine if treatment with alemtuzumab after natalizumab reduces disease activity in patients with relapsing forms of MS. This review article will outline the rationale and objectives of the sequential natalizumab – alemtuzumab therapy in patients with relapsing forms of multiple sclerosis (SUPPRESS; ClinicalTrials.gov ID: NCT03135249) trial in greater detail than would be feasible in a manuscript that summarizes the study results.

Methods

The SUPPRESS trial is single arm, open-label, multicenter, efficacy pilot study that aims to establish a disease-free state over a 24-months period in patients who received the natalizumab- alemtuzumab sequential therapy. Participants will be recruited from four different sites. The primary endpoint is the annualized relapse rate (ARR) from the time of cessation of natalizumab treatment. Key secondary endpoint is freedom of relapse at 12-months, the number of new/enlarging T2 lesions on magnetic resonance imaging (MRI), and the number of gadolinium (Gd)-enhancing lesions on MRI. An exploratory endpoint is the Expanded Disability Status Scale (EDSS), retinal nerve fiber layer (RNFL) thickness assessment by optic coherence tomography (OCT) and assessment of quality of life (QoL) measures by a pre-defined, self-administered testing battery. To evaluate immunological effects, blood leukocytes will be collected and immunophenotyped by multi-parameter flow cytometry.

Conclusion

The SUPPRESS trial will provide clinical, imaging, and biological data to determine whether sequential natalizumab to alemtuzumab combination therapy establish a disease-free state in patients with relapsing forms of MS.

Immunosenescence and Autoimmunity: Exploiting the T-Cell Receptor Repertoire to Investigate the Impact of Aging on Multiple Sclerosis

T-cell receptor (TCR) repertoire diversity is a determining factor for the immune system capability in fighting infections and preventing autoimmunity. During life, the TCR repertoire diversity progressively declines as a physiological aging progress. The investigation of TCR repertoire dynamics over life represents a powerful tool unraveling the impact of immunosenescence in health and disease. Multiple Sclerosis (MS) is a demyelinating, inflammatory, T-cell mediated autoimmune disease of the Central Nervous System in which age is crucial: it is the most widespread neurological disease among young adults and, furthermore, patients age may impact on MS progression and treatments outcome. Crossing knowledge on the TCR repertoire dynamics over MS patients' life is fundamental to investigate disease mechanisms, and the advent of high- throughput sequencing (HTS) has significantly increased our knowledge on the topic. Here we report an overview of current literature about the impact of immunosenescence and age-related TCR dynamics variation in autoimmunity, including MS.

CNS inflammation after natalizumab therapy for multiple sclerosis: A retrospective histopathological and CSF cohort study

Natalizumab, a recombinant humanized monoclonal antibody directed against the α4 subunit of the integrins α4ß1 and α4ß7, has been approved for the treatment of active relapsing-remitting MS. Although natalizumab is a highly beneficial drug that effectively reduces the risk of sustained disability progression and the rate of clinical relapses, some patients do not respond to it, and some are at higher risk of developing progressive multifocal leukoencephalopathy (PML). The histopathological effects after natalizumab therapy are still unknown. We, therefore, performed a detailed histological characterization of the CNS inflammatory cell infiltrate of 24 brain specimens from natalizumab treated patients, consisting of 20 biopsies and 4 autopsies and 21 MS controls. To complement the analysis, immune cells in blood and cerebrospinal fluid (CSF) of 30 natalizumab-treated patients and 42 MS controls were quantified by flow cytometry. Inflammatory infiltrates within lesions were mainly composed of T cells and macrophages, some B cells, plasma cells, and dendritic cells. There was no significant difference in the numbers of T cells or macrophages and microglial cells in lesions of natalizumab-treated patients as compared to controls. A shift towards cytotoxic T cells of a memory phenotype was observed in the CSF. Plasma cells were significantly increased in active demyelinating lesions of natalizumab-treated patients, but no correlation to clinical disability was observed. Dendritic cells within lesions were found to be reduced with longer ongoing therapy duration. Our findings suggest that natalizumab does not completely prevent immune cells from entering the CNS and is associated with an accumulation of plasma cells, the pathogenic and clinical significance of which is not known. As B cells are considered to serve as a reservoir of the JC virus, the observed plasma cell accumulation and reduction in dendritic cells in the CNS of natalizumab-treated patients may potentially play a role in PML development.

Evaluation of Natalizumab Pharmacokinetics and Pharmacodynamics: Toward Individualized Doses

Background: Plasma concentration of natalizumab falls above the therapeutic threshold in many patients who, therefore, receive more natalizumab than necessary and have higher risk of progressive multifocal leukoencephalopathy.

Objective: To assess in a single study the individual and treatment characteristics that influence the pharmacokinetics and pharmacodynamics of natalizumab in multiple sclerosis (MS) patients in the real-world practice.

Methods: Prospective observational study to analyse the impact of body weight, height, body surface area, body mass index, gender, age, treatment duration, and dosage scheme on natalizumab concentrations and the occupancy of α4-integrin receptor (RO) by natalizumab.

Results: Natalizumab concentrations ranged from 0.72 to 67 μg/ml, and RO from 26 to 100%. Body mass index inversely associated with natalizumab concentration (beta = −1.78; p ≤ 0.001), as it did body weight (beta = −0.34; p = 0.001), but not height, body surface area, age or gender Extended vs. standard dose scheme, but not treatment duration, was inversely associated with natalizumab concentration (beta = −7.92; p = 0.016). Similar to natalizumab concentration, body mass index (beta = −1.39; p = 0.001) and weight (beta = −0.31; p = 0.001) inversely impacted RO. Finally, there was a strong direct linear correlation between serum concentrations and RO until 9 μg/ml (rho = 0.71; p = 0.003). Nevertheless, most patients had higher concentrations of natalizumab resulting in the saturation of the integrin.

Conclusions: Body mass index and dosing interval are the main variables found to influence the pharmacology of natalizumab. Plasma concentration of natalizumab and/or RO are wide variable among patients and should be routinely measured to personalize treatment and, therefore, avoid either over and underdosing.

Phase II trial of natalizumab for the treatment of anti-Hu associated paraneoplastic neurological syndromes

Background

Paraneoplastic neurological syndromes with anti-Hu antibodies (Hu-PNS) have a very poor prognosis: more than half of the patients become bedridden and median survival is less than 12 months. Several lines of evidence suggest a pathogenic T cell-mediated immune response. Therefore, we conducted a prospective open-label phase II trial with natalizumab.

Methods

Twenty Hu-PNS patients with progressive disease were treated with a maximum of three monthly natalizumab cycles (300 mg). The primary outcome measure was functional improvement, this was defined as at least one point decrease in modified Rankin Scale (mRS) score at the last treatment visit. In addition, treatment response was assessed wherein a mRS score ≤3 after treatment was defined as treatment responsive.

Results

The median age at onset was 67.8 years (SD 8.4) with a female predominance (n = 17, 85%). The median time from symptom onset to Hu-PNS diagnosis was 5 months (IQR 2–11). Most patients had subacute sensory neuronopathy (n = 15, 75%), with a median mRS of 4 at baseline. Thirteen patients had a tumor, all small cell lung cancer. After natalizumab treatment, two patients (10%) showed functional improvement. Of the remaining patients, 60% had a stable functional outcome, while 30% showed further deterioration. Treatment response was classified as positive in nine patients (45%).

Conclusions

Natalizumab may ameliorate the disease course in Hu-PNS, but no superior effects above other reported immunosuppressive and immunomodulatory were observed. More effective treatment modalities are highly needed.

Trial registration

https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-000675-13/NL

Prediction of differentially expressed microRNAs in blood as potential biomarkers for Alzheimer's disease by meta-analysis and adaptive boosting ensemble learning

BACKGROUND

Blood circulating microRNAs that are specific for Alzheimer's disease (AD) can be identified from differentially expressed microRNAs (DEmiRNAs). However, non-reproducible and inconsistent reports of DEmiRNAs hinder biomarker development. The most reliable DEmiRNAs can be identified by meta-analysis. To enrich the pool of DEmiRNAs for potential AD biomarkers, we used a machine learning method called adaptive boosting for miRNA disease association (ABMDA) to identify eligible candidates that share similar characteristics with the DEmiRNAs identified from meta-analysis. This study aimed to identify blood circulating DEmiRNAs as potential AD biomarkers by augmenting meta-analysis with the ABMDA ensemble learning method.

METHODS

Studies on DEmiRNAs and their dysregulation states were corroborated with one another by meta-analysis based on a random-effects model. DEmiRNAs identified by meta-analysis were collected as positive examples of miRNA-AD pairs for ABMDA ensemble learning. ABMDA identified similar DEmiRNAs according to a set of predefined criteria. The biological significance of all resulting DEmiRNAs was determined by their target genes according to pathway enrichment analyses. The target genes common to both meta-analysis- and ABMDA-identified DEmiRNAs were collected to construct a network to investigate their biological functions.

RESULTS

A systematic database search found 7841 studies for an extensive meta-analysis, covering 54 independent comparisons of 47 differential miRNA expression studies, and identified 18 reliable DEmiRNAs. ABMDA ensemble learning was conducted based on the meta-analysis results and the Human MicroRNA Disease Database, which identified 10 additional AD-related DEmiRNAs. These 28 DEmiRNAs and their dysregulated pathways were related to neuroinflammation. The dysregulated pathway related to neuronal cell cycle re-entry (CCR) was the only statistically significant pathway of the ABMDA-identified DEmiRNAs. In the biological network constructed from 1865 common target genes of the identified DEmiRNAs, the multiple core ubiquitin-proteasome system, that is involved in neuroinflammation and CCR, was highly connected.

CONCLUSION

This study identified 28 DEmiRNAs as potential AD biomarkers in blood, by meta-analysis and ABMDA ensemble learning in tandem. The DEmiRNAs identified by meta-analysis and ABMDA were significantly related to neuroinflammation, and the ABMDA-identified DEmiRNAs were related to neuronal CCR.

Hippocampal subfield transcriptome analysis in schizophrenia psychosis

We have previously demonstrated functional and molecular changes in hippocampal subfields in individuals with schizophrenia (SZ) psychosis associated with hippocampal excitability. In this study, we use RNA-seq and assess global transcriptome changes in the hippocampal subfields, DG, CA3, and CA1 from individuals with SZ psychosis and controls to elucidate subfield-relevant molecular changes. We also examine changes in gene expression due to antipsychotic medication in the hippocampal subfields from our SZ ON- and OFF-antipsychotic medication cohort. We identify unique subfield-specific molecular profiles in schizophrenia postmortem samples compared with controls, implicating astrocytes in DG, immune mechanisms in CA3, and synaptic scaling in CA1. We show a unique pattern of subfield-specific effects by antipsychotic medication on gene expression levels with scant overlap of genes differentially expressed by SZ disease effect versus medication effect. These hippocampal subfield changes serve to confirm and extend our previous model of SZ and can explain the lack of full efficacy of conventional antipsychotic medication on SZ symptomatology. With future characterization using single-cell studies, the identified distinct molecular profiles of the DG, CA3, and CA1 in SZ psychosis may serve to identify further potential hippocampal-based therapeutic targets.

CD11c+CD88+CD317+ myeloid cells are critical mediators of persistent CNS autoimmunity

Natalizumab, a humanized monoclonal antibody (mAb) against α4-integrin, reduces the number of dendritic cells (DC) in cerebral perivascular spaces in multiple sclerosis (MS). Selective deletion of α4-integrin in CD11c+ cells should curtail their migration to the central nervous system (CNS) and ameliorate experimental autoimmune encephalomyelitis (EAE). We generated CD11c.Cre+/-ITGA4fl/fl C57BL/6 mice to selectively delete α4-integrin in CD11c+ cells. Active immunization and adoptive transfer EAE models were employed and compared with WT controls. Multiparameter flow cytometry was utilized to immunophenotype leukocyte subsets. Single-cell RNA sequencing was used to profile individual cells. α4-Integrin expression by CD11c+ cells was significantly reduced in primary and secondary lymphoid organs in CD11c.Cre+/-ITGA4fl/fl mice. In active EAE, a delayed disease onset was observed in CD11c.Cre+/-ITGA4fl/fl mice, during which CD11c+CD88+ cells were sequestered in the blood. Upon clinical EAE onset, CD11c+CD88+ cells appeared in the CNS and expressed CD317+ In adoptive transfer experiments, CD11c.Cre+/-ITGA4fl/fl mice had ameliorated clinical disease phenotype associated with significantly diminished numbers of CNS CD11c+CD88+CD317+ cells. In human cerebrospinal fluid from subjects with neuroinflammation, microglia-like cells display coincident expression of ITGAX (CD11c), C5AR1 (CD88), and BST2 (CD317). In mice, we show that only activated, but not naïve microglia expressed CD11c, CD88, and CD317. Finally, anti-CD317 treatment prior to clinical EAE substantially enhanced recovery in mice.

Neuroinflammation in neurodegenerative disorders: the roles of microglia and astrocytes

Neuroinflammation is associated with neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Microglia and astrocytes are key regulators of inflammatory responses in the central nervous system. The activation of microglia and astrocytes is heterogeneous and traditionally categorized as neurotoxic (M1-phenotype microglia and A1-phenotype astrocytes) or neuroprotective (M2-phenotype microglia and A2-phenotype astrocytes). However, this dichotomized classification may not reflect the various phenotypes of microglia and astrocytes. The relationship between these activated glial cells is also very complicated, and the phenotypic distribution can change, based on the progression of neurodegenerative diseases. A better understanding of the roles of microglia and astrocytes in neurodegenerative diseases is essential for developing effective therapies. In this review, we discuss the roles of inflammatory response in neurodegenerative diseases, focusing on the contributions of microglia and astrocytes and their relationship. In addition, we discuss biomarkers to measure neuroinflammation and studies on therapeutic drugs that can modulate neuroinflammation.

Occurrence and microstructural features of slowly expanding lesions on fingolimod or natalizumab treatment in multiple sclerosis

Background:

In multiple sclerosis (MS), up to 57% of white matter lesions are chronically active. These slowly expanding lesions (SELs) contribute to disability progression.

Objective:

The aim of this study is to compare fingolimod and natalizumab effects on progressive linearly enlarging lesions (i.e. SELs), a putative biomarker of smouldering inflammation.

Methods:

Relapsing-remitting MS patients starting fingolimod ( n = 24) or natalizumab ( n = 28) underwent 3T brain magnetic resonance imaging (MRI) at baseline, months 6, 12 and 24. SELs were identified among baseline-visible lesions showing ⩾ 12.5% of annual increase, calculated by linearly fitting the Jacobian of the nonlinear deformation field between timepoints obtained combining T1- and T2-weighted scans. SEL burden, magnetization transfer ratio (MTR) and T1 signal intensity were compared using linear models.

Results:

The prevalences of fingolimod (75%) and natalizumab patients (46%) with ⩾ 1 SEL were not significantly different (adjusted- p = 0.08). Fingolimod group had higher SEL number and volume (adjusted- p ⩽ 0.047, not false discovery rate (FDR) survived). In both groups, SELs versus non-SELs showed lower MTR and T1 signal intensity (adjusted- p ⩽ 0.01, FDR-survived). Longitudinally, non-SEL MTR increased in both treatment groups (adjusted- p ⩽ 0.005, FDR-survived). T1 signal intensity decreased in SELs with both treatments (adjusted- p ⩽ 0.049, FDR-survived in fingolimod group) and increased in natalizumab non-SELs (adjusted- p = 0.03, FDR-survived).

Conclusion:

The effects of natalizumab and fingolimod on SEL occurrence seem modest, with natalizumab being slightly more effective. Both treatments may promote reparative mechanisms in stable or chronic inactive lesions.

Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.

Reelin depletion protects against autoimmune encephalomyelitis by decreasing vascular adhesion of leukocytes

Neuroinflammation as a result of immune cell recruitment into the central nervous system (CNS) is a key pathogenic mechanism of multiple sclerosis (MS). However, current anti-inflammatory interventions depleting immune cells or directly targeting their trafficking into the CNS can have serious side effects, highlighting a need for better immunomodulatory strategies. We detected increased Reelin concentrations in the serum of patients with MS, resulting in increased endothelial permeability to leukocytes through increased nuclear factor κB-mediated expression of vascular adhesion molecules. We thus investigated the prophylactic and therapeutic potential of Reelin immunodepletion in experimental autoimmune encephalomyelitis (EAE) and further validated the results in Reelin knockout mice. Removal of plasma Reelin by either approach protected against neuroinflammation and largely abolished the neurological consequences by reducing endothelial permeability and immune cell accumulation in the CNS. Our findings suggest Reelin depletion as a therapeutic approach with an inherent good safety margin for the treatment of MS and other diseases where leukocyte extravasation is a major driver of pathogenicity.

Perspectives on Current and Novel Treatments for Inflammatory Bowel Disease

New therapeutic strategies in inflammatory bowel disease (IBD) have shifted from symptom control towards treat-to-target algorithms in order to optimize treatment results. The treatment of IBD has evolved with the development of tumor necrosis factor-α inhibitors beyond the conventional therapies. In spite of their long-term effectiveness, many patients do not respond to or cannot sustain treatment with these drugs, which have various side effects. Therefore, the development of new drugs targeting specific pathways in the pathogenesis of IBD has become necessary. Some novel biologics and small molecule drugs have shown potential in IBD clinical trials, providing safe and effective results. In addition, clinicians are now trying to target the dysbiotic microbiome of patients with IBD using fecal microbiota transplantation. New tools such as stem cells have also been developed. The available therapeutic options for IBD are expanding rapidly. In the next few years, physicians will face an unprecedented number of options when choosing the best treatments for patients with IBD. This review provides an overview of recent advances in IBD treatment options.

Limitations of cell-lineage-specific non-dynamic gene recombination in CD11c.Cre+ITGA4fl/fl mice

BACKGROUND

The Cre-lox system is a non-dynamic method of gene modification and characterization. Promoters thought to be relatively cell-specific are utilized for generation of cell-lineage-specific gene modifications.

METHODS

CD11c.Cre⁺ITGA4^fl/fl mice were generated to abolish the expression of ITGA (α4-integrin) in CD11c⁺ cells. Ex vivo flow cytometry studies were used to assess the expression of cellular surface markers in different lymphoid compartments and leukocytes subsets after Cre-mediated recombination.

RESULTS

A significant reduction of α4-integrin expression among CD11c^+- cells was achieved in CD11c.Cre⁺ITGA4^fl/fl mice in primary and secondary lymphoid tissues. A similar reduction in the expression of α4-integrin was also observed in CD11c^- cells.

CONCLUSION

Cre-lox-mediated cell lineage-specific gene deletion is limited by the transient expression of recombination regulating sequences in hematopoietic cell lines. These methodological issues indicate the need to consider when to employ non-dynamic DNA recombination models in animal models of CNS autoimmunity. An experimental algorithm to address the biological complexities of non-dynamic gene recombination is provided.

CD8 T-cell Recruitment Into the Central Nervous System of Cuprizone-Fed Mice: Relevance to Modeling the Etiology of Multiple Sclerosis

Cuprizone (CPZ)-feeding in mice induces atrophy of peripheral immune organs (thymus and spleen) and suppresses T-cell levels, thereby limiting its use as a model for studying the effects of the immune system in demyelinating diseases such as Multiple Sclerosis (MS). To investigate whether castration (Cx) can protect the peripheral immune organs from CPZ-induced atrophy and enable T-cell recruitment into the central nervous system (CNS) following a breach of the blood-brain barrier (BBB), three related studies were carried out. In Study 1, Cx prevented the dose-dependent reductions (0.1% < 0.2% CPZ) in thymic and splenic weight, size of the thymic medulla and splenic white pulp, and CD4 and CD8 (CD4/8) levels remained comparable to gonadally intact (Gi) control males. Importantly, 0.1% and 0.2% CPZ were equipotent at inducing central demyelination and glial activation. In Study 2, combining Cx with 0.1% CPZ-feeding and BBB disruption with pertussis toxin (PT) enhanced CD8⁺ T-cell recruitment into the CNS. The increased CD8⁺ T-cell level observed in the parenchyma of the cerebrum, cerebellum, brainstem and spinal cord were confirmed by flow cytometry and western blot analyses of CNS tissue. In Study 3, PT+0.1% CPZ-feeding to Gi female mice resulted in similar effects on the peripheral immune organs, CNS demyelination, and gliosis comparable to Gi males, indicating that testosterone levels alone were not responsible for the immune response seen in Study 2. The combination of Cx+0.1% CPZ-feeding+PT indicates that CPZ-induced demyelination can trigger an “inside-out” immune response when the peripheral immune system is spared and may provide a better model to study the initiating events in demyelinating conditions such as MS.

Lack of specific T- and B-cell clonal expansions in multiple sclerosis patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare, potentially devastating myelin-degrading disease caused by the JC virus. PML occurs preferentially in patients with compromised immune system, but has been also observed in multiple sclerosis (MS) patients treated with disease-modifying drugs. We characterized T and B cells in 5 MS patients that developed PML, 4 during natalizumab therapy and one after alemtuzumab treatment, and in treated patients who did not develop the disease. Results revealed that: i) thymic and bone marrow output was impaired in 4 out 5 patients at the time of PML development; ii) T-cell repertoire was restricted; iii) clonally expanded T cells were present in all patients. However, common usage or pairings of T-cell receptor beta variable or joining genes, specific clonotypes or obvious “public” T-cell response were not detected at the moment of PML onset. Similarly, common restrictions were not found in the immunoglobulin heavy chain repertoire. The data indicate that no JCV-related specific T- and B-cell expansions were mounted at the time of PML. The current results enhance our understanding of JC virus infection and PML, and should be taken into account when choosing targeted therapies.

Dendritic Cell Accumulation in the Gut and Central Nervous System Is Differentially Dependent on α4 Integrins

Homing of pathogenic CD4⁺ T cells to the CNS is dependent on α4 integrins. However, it is uncertain whether α4 integrins are also required for the migration of dendritic cell (DC) subsets, which sample Ags from nonlymphoid tissues to present it to T cells. In this study, after genetic ablation of Itga4 in DCs and monocytes in mice via the promoters of Cd11c and Lyz2 (also known as LysM), respectively, the recruitment of α4 integrin-deficient conventional and plasmacytoid DCs to the CNS was unaffected, whereas α4 integrin-deficient, monocyte-derived DCs accumulated less efficiently in the CNS during experimental autoimmune encephalomyelitis in a competitive setting than their wild-type counterparts. In a noncompetitive setting, α4 integrin deficiency on monocyte-derived DCs was fully compensated. In contrast, in small intestine and colon, the fraction of α4 integrin-deficient CD11b⁺CD103⁺ DCs was selectively reduced in steady-state. Yet, T cell-mediated inflammation and host defense against Citrobacter rodentium were not impaired in the absence of α4 integrins on DCs. Thus, inflammatory conditions can promote an environment that is indifferent to α4 integrin expression by DCs.

To the Brain and Back: Migratory Paths of Dendritic Cells in Multiple Sclerosis

Migration of dendritic cells (DC) to the central nervous system (CNS) is a critical event in the pathogenesis of multiple sclerosis (MS). While up until now, research has mainly focused on the transmigration of DC through the blood-brain barrier, experimental evidence points out that also the choroid plexus and meningeal vessels represent important gateways to the CNS, especially in early disease stages. On the other hand, DC can exit the CNS to maintain immunological tolerance to patterns expressed in the CNS, a process that is perturbed in MS. Targeting trafficking of immune cells, including DC, to the CNS has demonstrated to be a successful strategy to treat MS. However, this approach is known to compromise protective immune surveillance of the brain. Unravelling the migratory paths of regulatory and pathogenic DC within the CNS may ultimately lead to the design of new therapeutic strategies able to selectively interfere with the recruitment of pathogenic DC to the CNS, while leaving host protective mechanisms intact.

Vedolizumab in Japanese patients with ulcerative colitis: A Phase 3, randomized, double-blind, placebo-controlled study

Background

Vedolizumab safety and efficacy have been established in many populations all over the world, but have never been studied in Japan. We report results from a Phase 3, randomized, double-blind, placebo-controlled study of vedolizumab in Japanese patients with active ulcerative colitis (UC).

Methods

Patients with moderate-to-severe UC were enrolled into Cohort 1 (double-blinded) or Cohort 2 (open-label) in the induction phase. Cohort 1 was randomized 2:1 to receive 300 mg vedolizumab or placebo, while Cohort 2 received vedolizumab 300 mg only, at Weeks 0, 2, and 6. Patients from Cohorts 1 and 2 showing a clinical response to vedolizumab at Week 10 were randomized 1:1 to receive vedolizumab or placebo (double-blinded) at Week 14 and then every 8 weeks up to Week 54 as the maintenance phase. The primary endpoint was clinical response at Week 10, for the induction phase, and clinical remission at Week 60, for the maintenance phase.

Results

A total of 292 patients were enrolled into the induction phase (246 in Cohort 1, 46 in Cohort 2); 83 patients achieved response to vedolizumab and were subsequently enrolled into the maintenance phase. Clinical response rates at Week 10 were 39.6% (65/164) and 32.9% (27/82) in the vedolizumab and placebo groups in Cohort 1, respectively (adjusted odds ratio [AOR] = 1.37, 95% CI 0.779–2.399; p = 0.2722). In the maintenance phase, clinical remission rate at Week 60 was significantly higher in the vedolizumab group, at 56.1% (23/41), versus 31.0% (13/42) for placebo (AOR = 2.88, 95% CI 1.168–7.108; p = 0.0210). Most adverse events were mild to moderate in intensity, and no deaths occurred during the study period.

Conclusions

Vedolizumab showed numerically greater efficacy compared with placebo as induction therapy, but the difference was not statistically significant. Vedolizumab was significantly superior to placebo as maintenance therapy in Japanese patients with UC. Vedolizumab has favourable safety and tolerability in these patients.

Trial registration

ClinicalTrials.gov: NCT02039505.

Modulating acute neuroinflammation in intracerebral hemorrhage: the potential promise of currently approved medications for multiple sclerosis

The secondary inflammatory injury following intracerebral hemorrhage (ICH) results in increased morbidity and mortality. White blood cells have been implicated as critical mediators of this inflammatory injury. Currently, no medications have been clinically proven to ameliorate or beneficially modulate inflammation, or to improve outcomes by any mechanism, following ICH. However, other neuroinflammatory conditions, such as multiple sclerosis, have approved pharmacologic therapies that modulate the inflammatory response and minimize the damage caused by inflammatory cells. Thus, there is substantial interest in existing therapies for neuroinflammation and their potential applicability to other acute neurological diseases such as ICH. In this review, we examined the mechanism of action of twelve currently approved medications for multiple sclerosis: alemtuzumab, daclizumab, dimethyl fumarate, fingolimod, glatiramer acetate, interferon beta-1a, interferon beta-1b, mitoxantrone, natalizumab, ocrelizumab, rituximab, teriflunomide. We analyzed the existing literature pertaining to the effects of these medications on various leukocytes and also with emphasis on mechanisms of action during the acute period following initiation of therapy. As a result, we provide a valuable summary of the current body of knowledge regarding these therapies and evidence that supports or refutes their likely promise for treating neuroinflammation following ICH.

TLR3 agonism re-establishes CNS immune competence during α4-integrin deficiency

OBJECTIVE

Natalizumab blocks α4-integrin-mediated leukocyte migration into the central nervous system (CNS). It diminishes disease activity in multiple sclerosis (MS), but carries a high risk of progressive multifocal encephalopathy (PML), an opportunistic infection with JV virus that may be prompted by diminished CNS immune surveillance. The initial host response to viral infections entails the synthesis of type I interferons (IFN) upon engagement of TLR3 receptors. We hypothesized that TLR3 agonism reestablishes CNS immune competence in the setting of α4-integrin deficiency.

METHOD

We generated the conditional knock out mouse strain Mx1.Cre+ α4-integrinfl/fl, in which the α4-integrin gene is ablated upon treatment with the TLR3 agonist poly I:C. Adoptive transfer of purified lymphocytes from poly I:C-treated Mx1.Cre+ α4-integrinfl/fl donors into naive recipients recapitulates immunosuppression under natalizumab. Active experimental autoimmune encephalomyelitis (EAE) in Mx1.Cre+ α4-integrinfl/fl mice treated with poly I:C represents immune-reconstitution.

RESULTS

Adoptive transfer of T cells from poly I:C treated Mx1.Cre+ α4-integrinfl/fl mice causes minimal EAE. The in vitro migratory capability of CD45+ splenocytes from these mice is reduced. In contrast, actively-induced EAE after poly I:C treatment results in full disease susceptibility of Mx1.Cre+ α4-integrinfl/fl mice, and the number and composition of CNS leukocytes is similar to controls. Extravasation of Evans Blue indicates a compromised blood-brain barrier. Poly I:C treatment results in a 2-fold increase in IFN β transcription in the spinal cord.

INTERPRETATION

Our data suggest that TLR3 agonism in the setting of relative α4-integrin deficiency can reestablish CNS immune surveillance in an experimental model. This pathway may present a feasible treatment strategy to treat and prevent PML under natalizumab therapy and should be considered for further experimental evaluation in a controlled setting.

A Phase 1, Multiple-Dose Study of Vedolizumab in Japanese Patients With Ulcerative Colitis

Although previous studies have shown that patients with ulcerative colitis may benefit from treatment with vedolizumab, a humanized monoclonal antibody targeting the α₄β₇ integrin heterodimer, no data exist in Japanese populations. The aim of this phase 1, open‐label, multicenter study was to assess the pharmacokinetics, pharmacodynamics, efficacy, and safety of vedolizumab in Japanese patients with ulcerative colitis. Adult patients with confirmed ulcerative colitis received either 150 mg (step 1) or 300 mg (step 2) of intravenous (IV) vedolizumab on days 1, 15, and 43 of the study protocol. Pharmacokinetic, pharmacodynamic, safety, and efficacy parameters were all assessed through study end (day 239). Nine patients were enrolled in this study (150 mg, n = 3; 300 mg, n = 6). Patients who received vedolizumab IV 300 mg had approximately twice the drug exposure of those receiving vedolizumab IV 150 mg (day 1 AUC_day14 744 vs 408 μg·d/mL) and a longer‐lasting maximal saturation of α₄β₇ integrin (155 vs 99 days). The number of treatment‐emergent adverse events, all of which were mild or moderate in intensity, was similar between the 150‐mg (15 events) and 300‐mg (20 events) groups. The 2 patients (150 mg group) not in clinical remission by partial Mayo score at the start of the study met the criteria for clinical remission on days 15 and 155 of the study, respectively. In conclusion, in Japanese patients with ulcerative colitis, vedolizumab showed similar pharmacokinetic and pharmacodynamic results to those seen in non‐Japanese patients. Vedolizumab was well tolerated and demonstrated clinical activity consistent with previous studies.

Inflammageing: chronic inflammation in ageing, cardiovascular disease, and frailty

Most older individuals develop inflammageing, a condition characterized by elevated levels of blood inflammatory markers that carries high susceptibility to chronic morbidity, disability, frailty, and premature death. Potential mechanisms of inflammageing include genetic susceptibility, central obesity, increased gut permeability, changes to microbiota composition, cellular senescence, NLRP3 inflammasome activation, oxidative stress caused by dysfunctional mitochondria, immune cell dysregulation, and chronic infections. Inflammageing is a risk factor for cardiovascular diseases (CVDs), and clinical trials suggest that this association is causal. Inflammageing is also a risk factor for chronic kidney disease, diabetes mellitus, cancer, depression, dementia, and sarcopenia, but whether modulating inflammation beneficially affects the clinical course of non-CVD health problems is controversial. This uncertainty is an important issue to address because older patients with CVD are often affected by multimorbidity and frailty - which affect clinical manifestations, prognosis, and response to treatment - and are associated with inflammation by mechanisms similar to those in CVD. The hypothesis that inflammation affects CVD, multimorbidity, and frailty by inhibiting growth factors, increasing catabolism, and interfering with homeostatic signalling is supported by mechanistic studies but requires confirmation in humans. Whether early modulation of inflammageing prevents or delays the onset of cardiovascular frailty should be tested in clinical trials.

Past, Present and Future of Therapeutic Interventions Targeting Leukocyte Trafficking in Inflammatory Bowel Disease

Studies in the 1990s using animal models of intestinal inflammation delineated the crucial molecules involved in leukocyte attraction and retention to the inflamed gut and associated lymphoid tissues. The first drug targeting leukocyte trafficking tested in inflammatory bowel diseases was the anti-ICAM-1 antisense oligonucleotide alicaforsen, showing only modest efficacy. Subsequently, the anti-α4 monoclonal antibody natalizumab proved efficacious for induction and maintenance of remission in Crohn's disease, but was associated with progressive multifocal leukoencephalopathy due to its ability to interfere with both α4β1 and α4β7 function. Later developments in this area took advantage of the fairly selective expression of MAdCAM-1 in the digestive organs, showing that vedolizumab, a more specific monoclonal antibody selectively blocking MAdCAM-1 binding to integrin α4β7, was efficacious for induction and maintenance of remission in ulcerative colitis and Crohn's disease, and it was not associated with neurological complications. Currently, other drugs targeting the β7 subunit, immunoglobulin superfamily molecules expressed on the endothelium, as well as blockade of lymphocyte recirculation in lymph nodes through modulation of sphingosine 1-phosphate receptors are under development. The potential use and risks of combined anti-trafficking therapy will be examined in this review.

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.

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.

Reduction of PK11195 uptake observed in multiple sclerosis lesions after natalizumab initiation

OBJECTIVE

The objective of this study is to longitudinally analyze the uptake of [¹¹C]PK11195-PET in multiple sclerosis patients after 3 and 6 months of natalizumab treatment.

METHODS

Eighteen MS patients, starting treatment with monocloncal anti-VLA-4, were enrolled in a longitudinal PK-PET study. PK uptake was quantified by volume of distribution (VT) calculation using image-derived input function at baseline, 3 and 6 months. Pharmacokinetic quantification was done using a segmented MRI, and selected areas included white matter, gadolinium enhancing lesions, non-enhancing lesions, cortical grey matter and thalamus. VTs of lesions were calculated in reference to each patient's white matter (VT ratio=VTr), to consider physiologic variability.

RESULTS

Test-retest variability was stable for healthy control (HC). Quantification of PK uptake was completed in 18 patients, and baseline uptake was compared to 6-month uptake. After the start of natalizumab VTr significantly decreased in 13 individual enhancing lesions present within 5 patients (p=0.001). Moreover, VTr of the sum of non-enhancing lesions showed a moderate decrease (p=0.03). No longitudinal changes were detected in normal appearing white matter, the thalamus and cortical grey matter.

CONCLUSION

A reduction in PK11195 uptake was observed in both enhancing and chronic lesions after the start of natalizumab. PK11195 PET can be used as tool to assess the longitudinal change in MS lesions.

An Overview of the Mechanism of Action of the Monoclonal Antibody Vedolizumab

Vedolizumab is a novel therapeutic monoclonal antibody recently approved for the treatment of moderately to severely active ulcerative colitis and Crohn's disease in adults who have failed at least one conventional therapy. An integrin antagonist, vedolizumab binds to the α₄β₇ integrin which is expressed specifically by a subset of gastrointestinal-homing T lymphocytes. The binding of α₄β₇ integrin to mucosal addressin cell adhesion molecule-1 expressed on the surface of mucosal endothelial cells is a crucial component of the gut-selective homing mechanism for lymphocytes.In contrast, other monoclonal antibodies approved for the treatment of inflammatory bowel diseases, such as tumour necrosis factor α antagonists and the integrin antagonist natalizumab, act systemically or on multiple targets to reduce inflammation.The unique gut selectivity of vedolizumab may contribute to the favourable benefit-risk profile observed in vedolizumab clinical trials. In this review, we summarise data from the preclinical development of vedolizumab and describe the current understanding of the mechanism of action as it relates to other biological therapies for inflammatory bowel disease.

Dendritic cells in central nervous system autoimmunity

Dendritic cells (DCs) operate at the intersection of the innate and adaptive immune systems. DCs can promote or inhibit adaptive immune responses against neuroantigens. While DC intrinsic properties, i.e., their maturation state or the subset they belong to, are important determinants of the outcome of an autoimmune reaction, tissue-specific cues might also be relevant for the function of DCs. Thus, a better understanding of the performance of distinct DC subsets in specific anatomical niches, not only in lymphoid tissue but also in non-lymphoid tissues such as the meninges, the choroid plexus, and the inflamed CNS parenchyma, will be instrumental for the design of immune intervention strategies to chronic inflammatory diseases that do not put at risk basic surveillance functions of the immune system in the CNS. Here, we will review modern concepts of DC biology in steady state and during autoimmune neuroinflammation.

Dendritic cells as therapeutic targets in neuroinflammation

Multiple sclerosis (MS) is the most common chronic inflammatory demyelinating disorder of the central nervous system characterized by infiltration of immune cells and progressive damage to myelin sheaths and neurons. There is still no cure for the disease, but drug regimens can reduce the frequency of relapses and slightly delay progression. Myeloid cells or antigen-presenting cells (APCs) such as dendritic cells (DC), macrophages, and resident microglia, are key players in both mediating immune responses and inducing immune tolerance. Mounting evidence indicates a contribution of these myeloid cells to the pathogenesis of multiple sclerosis and to the effects of treatment, the understanding of which might provide strategies for more potent novel therapeutic interventions. Here, we review recent insights into the role of APCs, with specific focus on DCs in the modulation of neuroinflammation in MS.

Tanshinone IIA attenuates experimental autoimmune encephalomyelitis in rats

Multiple sclerosis (MS) is an inflammatory autoimmune neurodegenerative disease, which features focal demyelination and inflammatory cell infiltration of the brain and the spinal cord. Tanshinone IIA (TSIIA), one of the major fat‑soluble components of Salvia miltiorrhiza (Danshen), has anti‑inflammatory, immunoregulatory and neuroprotective activity; however, its efficacy in MS remains unknown. The current study was designed to investigate the potential therapeutic function of TSIIA on MS in the experimental autoimmune encephalomyelitis (EAE) rat model. In comparison to the vehicle control group, the TSIIA‑treated groups showed notably improved clinical symptoms and pathological changes, including central nervous system inflammatory cell infiltration and demyelination. Following administration of TSIIA, the quantity of CD4+ T cells, CD8+ T cells and macrophages/microglia in the spinal cord were reduced to different extents. Furthermore, TSIIA was also shown to downregulate interleukin (IL)‑17 and IL‑23 levels in the brain and serum of EAE rats. The results collectively provide evidence that TSIIA alleviates EAE and support its utility as a novel therapy for MS.

Current pharmacotherapy and putative disease-modifying therapy for Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease of the central nervous system correlated with the progressive loss of cognition and memory. β-Amyloid plaques, neurofibrillary tangles and the deficiency in cholinergic neurotransmission constitute the major hallmarks of the AD. Two major hypotheses have been implicated in the pathogenesis of AD namely the cholinergic hypothesis which ascribed the clinical features of dementia to the deficit cholinergic neurotransmission and the amyloid cascade hypothesis which emphasized on the deposition of insoluble peptides formed due to the faulty cleavage of the amyloid precursor protein. Current pharmacotherapy includes mainly the acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor agonist which offer symptomatic therapy and does not address the underlying cause of the disease. The disease-modifying therapy has garnered a lot of research interest for the development of effective pharmacotherapy for AD. β and γ-Secretase constitute attractive targets that are focussed in the disease-modifying approach. Potentiation of α-secretase also seems to be a promising approach towards the development of an effective anti-Alzheimer therapy. Additionally, the ameliorative agents that prevent aggregation of amyloid peptide and also the ones that modulate inflammation and oxidative damage associated with the disease are focussed upon. Development in the area of the vaccines is in progress to combat the characteristic hallmarks of the disease. Use of cholesterol-lowering agents also is a fruitful strategy for the alleviation of the disease as a close association between the cholesterol and AD has been cited. The present review underlines the major therapeutic strategies for AD with focus on the new developments that are on their way to amend the current therapeutic scenario of the disease.

Exploring potential mechanisms of action of natalizumab in secondary progressive multiple sclerosis

Multiple sclerosis (MS) is a common and chronic central nervous system (CNS) demyelinating disease and a leading cause of permanent disability. Patients most often present with a relapsing-remitting disease course, typically progressing over time to a phase of relentless advancement in secondary progressive MS (SPMS), for which approved disease-modifying therapies are limited. In this review, we summarize the pathophysiological mechanisms involved in the development of SPMS and the rationale and clinical potential for natalizumab, which is currently approved for the treatment of relapsing forms of MS, to exert beneficial effects in reducing disease progression unrelated to relapses in SPMS. In both forms of MS, active brain-tissue injury is associated with inflammation; but in SPMS, the inflammatory response occurs at least partly behind the blood-brain barrier and is followed by a cascade of events, including persistent microglial activation that may lead to chronic demyelination and neurodegeneration associated with irreversible disability. In patients with relapsing forms of MS, natalizumab therapy is known to significantly reduce intrathecal inflammatory responses which results in reductions in brain lesions and brain atrophy as well as beneficial effects on clinical measures, such as reduced frequency and severity of relapse and reduced accumulation of disability. Natalizumab treatment also reduces levels of cerebrospinal fluid chemokines and other biomarkers of intrathecal inflammation, axonal damage and demyelination, and has demonstrated the ability to reduce innate immune activation and intrathecal immunoglobulin synthesis in patients with MS. The efficacy of natalizumab therapy in SPMS is currently being investigated in a randomized, double-blind, placebo-controlled trial.

Cutting Edge: CD99 Is a Novel Therapeutic Target for Control of T Cell-Mediated Central Nervous System Autoimmune Disease

Leukocyte trafficking into the CNS is a prominent feature driving the immunopathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis. Blocking the recruitment of inflammatory leukocytes into the CNS represents an exploitable therapeutic target; however, the adhesion molecules that specifically regulate the step of leukocyte diapedesis into the CNS remain poorly understood. We report that CD99 is critical for lymphocyte transmigration without affecting adhesion in a human blood-brain barrier model. CD99 blockade in vivo ameliorated experimental autoimmune encephalomyelitis and decreased the accumulation of CNS inflammatory infiltrates, including dendritic cells, B cells, and CD4(+) and CD8(+) T cells. Anti-CD99 therapy was effective when administered after the onset of disease symptoms and blocked relapse when administered therapeutically after disease symptoms had recurred. These findings underscore an important role for CD99 in the pathogenesis of CNS autoimmunity and suggest that it may serve as a novel therapeutic target for controlling neuroinflammation.

Inflammatory Eicosanoids Increase Amyloid Precursor Protein Expression via Activation of Multiple Neuronal Receptors

Senile plaques comprised of Aβ peptides are a hallmark of Alzheimer's disease (AD) brain, as are activated glia that release inflammatory molecules, including eicosanoids. Previous studies have demonstrated that amyloid precursor protein (APP) and Aβ levels can be increased through activation of thromboxane A2-prostanoid (TP) receptors on neurons. We demonstrate that TP receptor regulation of APP expression depends on Gαq-signaling and conventional protein kinase C isoforms. Importantly, we discovered that Gαq-linked prostaglandin E2 and leukotriene D4 receptors also regulate APP expression. Prostaglandin E2 and thromboxane A2, as well as total APP levels, were found to be elevated in the brains of aged 5XFAD transgenic mice harboring Aβ plaques and activated glia, suggesting that increased APP expression resulted from eicosanoid binding to Gαq-linked neuronal receptors. Notably, inhibition of eicosanoid synthesis significantly lowered brain APP protein levels in aged 5XFAD mice. These results provide new insights into potential AD therapeutic strategies.

Migration of encephalitogenic CD8 T cells into the central nervous system is dependent on the α4β1-integrin

Although CD8 T cells are key players in neuroinflammation, little is known about their trafficking cues into the central nervous system (CNS). We used a murine model of CNS autoimmunity to define the molecules involved in cytotoxic CD8 T‐cell migration into the CNS. Using a panel of mAbs, we here show that the α4β1‐integrin is essential for CD8 T‐cell interaction with CNS endothelium. We also investigated which α4β1‐integrin ligands expressed by endothelial cells are implicated. The blockade of VCAM‐1 did not protect against autoimmune encephalomyelitis, and only partly decreased the CD8⁺ T‐cell infiltration into the CNS. In addition, inhibition of junctional adhesion molecule‐B expressed by CNS endothelial cells also decreases CD8 T‐cell infiltration. CD8 T cells may use additional and possibly unidentified adhesion molecules to gain access to the CNS.

High interindividual variability in the CD4/CD8 T cell ratio and natalizumab concentration levels in the cerebrospinal fluid of patients with multiple sclerosis

Strongly decreased leucocyte counts and a reduced CD4/CD8 T cell ratio in the cerebrospinal fluid (CSF) of natalizumab (NZB)-treated multiple sclerosis (MS) patients may have implications on central nervous (CNS) immune surveillance. With regard to NZB-associated progressive multi-focal leucoencephalopathy, we aimed at delineating a relationship between free NZB, cell-bound NZB, adhesion molecule (AM) expression and the treatment-associated shift in the CSF T cell ratio. Peripheral blood (PB) and CSF T cells from 15 NZB-treated MS patients, and CSF T cells from 10 patients with non-inflammatory neurological diseases and five newly diagnosed MS patients were studied. Intercellular adhesion molecule-1 (ICAM-1), leucocyte function antigen-1 (LFA-1), very late activation antigen-4 (VLA-4), NZB saturation levels, and T cell ratios were analysed by flow cytometry. NZB concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Lower NZB saturation levels (P<0.02) and a higher surface expression of ICAM-1 and LFA-1 (P<0.001) were observed on CSF CD8 T cells. CSF T cell ratios (0.3-2.1) and NZB concentrations (0.01-0.42 µg/ml) showed a pronounced interindividual variance. A correlation between free NZB, cell-bound NZB or AM expression levels and the CSF T cell ratio was not found. Extremely low NZB concentrations and a normalized CSF T cell ratio were observed in one case. The differential NZB saturation and AM expression of CSF CD8 T cells may contribute to their relative enrichment in the CSF. The reduced CSF T cell ratio appeared sensitive to steady-state NZB levels, as normalization occurred quickly. The latter may be important concerning a fast reconstitution of CNS immune surveillance.