Effective combination of minocycline and interferon-β in a model of multiple sclerosis

Tetracyclines Diminish In Vitro IFN-γ and IL-17-Producing Adaptive and Innate Immune Cells in Multiple Sclerosis

Introduction

Limited data from clinical trials in multiple sclerosis (MS) reported that minocycline, a widely used antibiotic belonging to the family of tetracyclines (TCs), exerts a beneficial short-lived clinical effect A similar anti-inflammatory effect of minocycline attributed to a deviation from Th1 to Th2 immune response has been reported in experimental models of MS. Whether such an immunomodulatory mechanism is operated in the human disease remains largely unknown.

Aim

To assess the in vitro immunomodulatory effect of tetracyclines, and in particular minocycline and doxycycline, in naïve and treated patients with MS.

Material and Methods

Peripheral blood mononuclear cells from 45 individuals (35 MS patients, amongst which 15 naïve patients and 10 healthy controls, HCs) were cultured with minocycline or doxycycline and conventional stimulants (PMA/Ionomycin or IL-12/IL-18). IFN-γ and IL-17 producing T-, NK- and NKT cells were assessed by flow cytometry. The effect of TCs on cell viability and apoptosis was further assessed by flow cytometry with Annexin V staining.

Results

Both tetracyclines significantly decreased, in a dose dependent manner, IFN-γ production in NKT and CD4⁺ T lymphocytes from MS patients (naïve or treated) stimulated with IL-12/IL-18 but did not decrease IFN-γ producing CD8⁺ T cells from naive MS or treated RRMS patients. They also decreased IL-17⁺ T and NKT cells following PMA and Ionomycin-stimulation. Tetracyclines did not affect the viability of cell subsets.

Conclusion

Tetracyclines can in vitro suppress IFN-γ and IL-17- producing cells from MS patients, and this may explain their potential therapeutic effect in vivo.

Failed, Interrupted, or Inconclusive Trials on Neuroprotective and Neuroregenerative Treatment Strategies in Multiple Sclerosis: Update 2015-2020

In the recent past, a plethora of drugs have been approved for the treatment of multiple sclerosis (MS). These therapeutics are mainly confined to immunomodulatory or immunosuppressive strategies but do not sufficiently address remyelination and neuroprotection. However, several neuroregenerative agents have shown potential in pre-clinical research and entered Phase I to III clinical trials. Although none of these compounds have yet proceeded to approval, understanding the causes of failure can broaden our knowledge about neuroprotection and neuroregeneration in MS. Moreover, most of the investigated approaches are characterised by consistent mechanisms of action and proved convincing efficacy in animal studies. Therefore, learning from their failure will help us to enforce the translation of findings acquired in pre-clinical studies into clinical application. Here, we summarise trials on MS treatment published since 2015 that have either failed or were interrupted due to a lack of efficacy, adverse events, or for other reasons. We further outline the rationale underlying these drugs and analyse the background of failure to gather new insights into MS pathophysiology and optimise future study designs. For conciseness, this review focuses on agents promoting remyelination and medications with primarily neuroprotective properties or unconventional approaches. Failed clinical trials that pursue immunomodulation are presented in a separate article.

Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis, originally experimental allergic encephalomyelitis, is the well-known animal model of multiple sclerosis, an immune- mediated, demyelinating, inflammatory chronic disease of the central nervous system. The experimental disease is widely utilized to test new therapies in preclinical studies, to investigate new hypothesis on the possible pathogenic mechanisms of autoimmune reaction directed against the central nervous system or more generally to investigate the interactions between the immune system and the central nervous system that lead to neuroinflammation. The experimental autoimmune encephalomyelitis may be induced following different protocols in mammals, including nonhuman primates, and autoreactive CD4+ T-lymphocytes directed against myelin antigens are the main factors. Here, after introducing the model, we describe the protocol to induce active EAE in inbred mice, we report on a table the different clinical courses of EAE depending on the combination of antigen /mouse strain and we provide indications on how to evaluate the clinics and pathology of this induced disease.

Minocycline in neurodegenerative and psychiatric diseases: An update

BACKGROUND AND PURPOSE

Minocycline is a broad-spectrum antibiotic, effective as a chronic treatment for recurrent bacterial infections. Beyond its antibiotic action, minocycline also has important anti-inflammatory, antioxidant and antiapoptotic properties. Its efficacy has therefore been evaluated in many neurodegenerative and psychiatric diseases that have an inflammatory basis. Our aim was to review preclinical and clinical studies performed in neurological and psychiatric diseases whose treatment involved the use of minocycline and thereby to discern the possible beneficial effect of minocycline in these disorders.

METHODS

Completed and ongoing preclinical studies and clinical trials of minocycline for both neurodegenerative diseases and psychiatric disorders, published from January 1995 to January 2020, were identified through searching relevant databases (https://www.ncbi.nlm.nih.gov/pubmed/, https://clinicaltrials.gov/). A total of 74 preclinical studies and 44 clinical trials and open-label studies were selected.

RESULTS

The results of the nearly 20 years of research identified are diverse. While minocycline mostly proved to be effective in animal models, clinical results showed divergent outcomes, with positive results in some studies counterbalanced by a number of cases with no significant improvements. Specific data for each disease are further individually described in this review.

CONCLUSIONS

Despite minocycline demonstrating antioxidant and anti-inflammatory effects, discrepancies between preclinical and clinical data indicate that we should be cautious in analyzing the outcomes. Improving and standardizing protocols and refining animal models could help us to determine if minocycline really is a useful drug in the treatment of these pathologies.

T Cell Delivery of Nanoparticles-Bound Anti-CD20 Monoclonal Antibody: Successful B Cell Depletion in the Spinal Cord during Experimental Autoimmune Encephalomyelitis

We developed a nanotechnology based-cell mediated drug delivery system by loading myelin antigen-specific T cells with nanoparticles bound to anti-CD20 monoclonal antibody. Anti-CD20 antibody is a current treatment (ocrelizumab) for multiple sclerosis (MS), a chronic, inflammatory and autoimmune disease of the central nervous system (CNS). CD20-depletion has been associated with efficacy in active relapsing and progressive MS, but may not efficiently target inflammatory cells compartmentalized in the CNS. In our work, the intravenous transfer of T cells containing nanoparticle-anti-CD20 complex in mice causes B cell depletion in the spleen and in the brain, whereas the injection of anti-CD20 alone depletes B cells only in the spleen. Testing this system in Experimental Autoimmune Encephalomyelitis (EAE), animal model of MS, we found that spinal cord B cell depletion ameliorates the disease course and pathology. Graphical Abstract.

Progressive multiple sclerosis: from pathophysiology to therapeutic strategies

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that involves demyelination and axonal degeneration. Although substantial progress has been made in drug development for relapsing-remitting MS, treatment of the progressive forms of the disease, which are characterized clinically by the accumulation of disability in the absence of relapses, remains unsatisfactory. This unmet clinical need is related to the complexity of the pathophysiological mechanisms involved in MS progression. Chronic inflammation, which occurs behind a closed blood-brain barrier with activation of microglia and continued involvement of T cells and B cells, is a hallmark pathophysiological feature. Inflammation can enhance mitochondrial damage in neurons, which, consequently, develop an energy deficit, further reducing axonal health. The growth-inhibitory and inflammatory environment of lesions also impairs remyelination, a repair process that might protect axons from degeneration. Moreover, neurodegeneration is accelerated by the altered expression of ion channels on denuded axons. In this Review, we discuss the current understanding of these disease mechanisms and highlight emerging therapeutic strategies based on these insights, including those targeting the neuroinflammatory and degenerative aspects as well as remyelination-promoting approaches.

Minocycline prevents the development of depression-like behavior and hippocampal inflammation in a rat model of Alzheimer's disease

RATIONALE

Considerable clinical and experimental studies have shown that depression-related disorders are the most common neuropsychiatric symptoms in Alzheimer's disease (AD), affecting as many as 20-40% of patients. An increasing amount of evidence shows that monoamine-based antidepressant treatments are not completely effective for depression treatment in patients with dementia. Minocycline, a second-generation tetracycline antibiotic, has been gaining research and clinical attention for the treatment of different neuropsychiatric disorders, and more recently depression symptom in humans.

METHODS

In the present study, we investigated the effects of Aβ1-42 administration alone or in combination with minocycline treatment on depression-like behaviors and anti/pro-inflammatory cytokines such as interleukin(IL)-10, IL-β, and tumor necrosis factor (TNF)-α in the hippocampus of rats.

RESULTS

Our results showed that Aβ1-42 administration increased depression-related behaviors in sucrose preference test, tail suspension test, novelty-suppressed feeding test, and forced swim test. We also found significant increases in IL-1β and TNF-α levels in the hippocampus of Aβ1-42-treated rats. Interestingly, minocycline treatment significantly reversed depression-related behaviors and the levels of hippocampal cytokines in Aβ1-42-treated rats.

CONCLUSION

These findings support the idea that there is a significant relationship among AD, depression-related symptoms, and pro-inflammatory cytokines in the brain, and suggest that antidepressant-like impacts of minocycline could be due to its anti-inflammatory properties. This drug could be of potential interest for the treatment of depression in patients with Alzheimer's disease.

Microglia and CNS Interleukin-1: Beyond Immunological Concepts

Activation of microglia and expression of the inflammatory cytokine interleukin-1 (IL-1) in the CNS have become almost synonymous with neuroinflammation. In numerous studies, increased CNS IL-1 expression and altered microglial morphology have been used as hallmarks of CNS inflammation. A central concept of how CNS IL-1 and microglia influence functions of the nervous system was derived from the notion initially generated in the peripheral immune system: IL-1 stimulates monocyte/macrophage (the peripheral counterparts of microglia) to amplify inflammation. It is increasingly clear, however, CNS IL-1 acts on other targets in the CNS and microglia participates in many neural functions that are not related to immunological activities. Further, CNS exhibits immunological privilege (although not as absolute as previously thought), rendering amplification of inflammation within CNS under stringent control. This review will analyze current literature to evaluate the contribution of immunological and non-immunological aspects of microglia/IL-1 interaction in the CNS to gain insights for how these aspects might affect health and disease in the nervous tissue.

Systematic screening of generic drugs for progressive multiple sclerosis identifies clomipramine as a promising therapeutic

The treatment of progressive multiple sclerosis (MS) is unsatisfactory. One reason is that the drivers of disease, which include iron-mediated neurotoxicity, lymphocyte activity, and oxidative stress, are not simultaneously targeted. Here we present a systematic screen to identify generic, orally available medications that target features of progressive MS. Of 249 medications that cross the blood–brain barrier, 35 prevent iron-mediated neurotoxicity in culture. Of these, several antipsychotics and antidepressants strongly reduce T-cell proliferation and oxidative stress. We focus on the antidepressant clomipramine and found that it additionally inhibits B-lymphocyte activity. In mice with experimental autoimmune encephalomyelitis, a model of MS, clomipramine ameliorates clinical signs of acute and chronic phases. Histologically, clomipramine reduces inflammation and microglial activation, and preserves axonal integrity. In summary, we present a systematic approach to identify generic medications for progressive multiple sclerosis with the potential to advance rapidly into clinical trials, and we highlight clomipramine for further development.

Progressive multiple sclerosis is an inflammatory and degenerative disease of the central nervous system, for which effective treatment is lacking. The authors carry out a screen to identify orally available generic medications, and show that the antidepressant clomipramine reduces pathology in mouse models.

Traumatic Spinal Cord Injury-Repair and Regeneration

BACKGROUND

Traumatic spinal cord injuries (SCI) have devastating consequences for the physical, financial, and psychosocial well-being of patients and their caregivers. Expediently delivering interventions during the early postinjury period can have a tremendous impact on long-term functional recovery.

PATHOPHYSIOLOGY

This is largely due to the unique pathophysiology of SCI where the initial traumatic insult (primary injury) is followed by a progressive secondary injury cascade characterized by ischemia, proapoptotic signaling, and peripheral inflammatory cell infiltration. Over the subsequent hours, release of proinflammatory cytokines and cytotoxic debris (DNA, ATP, reactive oxygen species) cyclically adds to the harsh postinjury microenvironment. As the lesions mature into the chronic phase, regeneration is severely impeded by the development of an astroglial-fibrous scar surrounding coalesced cystic cavities. Addressing these challenges forms the basis of current and upcoming treatments for SCI.

MANAGEMENT

This paper discusses the evidence-based management of a patient with SCI while emphasizing the importance of early definitive care. Key neuroprotective therapies are summarized including surgical decompression, methylprednisolone, and blood pressure augmentation. We then review exciting neuroprotective interventions on the cusp of translation such as Riluzole, Minocycline, magnesium, therapeutic hypothermia, and CSF drainage. We also explore the most promising neuroregenerative strategies in trial today including Cethrin™, anti-NOGO antibody, cell-based approaches, and bioengineered biomaterials. Each section provides a working knowledge of the key preclinical and patient trials relevant to clinicians while highlighting the pathophysiologic rationale for the therapies.

CONCLUSION

We conclude with our perspectives on the future of treatment and research in this rapidly evolving field.

Selected gene profiles of stressed NSC-34 cells and rat spinal cord following peripheral nerve reconstruction and minocycline treatment

The present study was conducted to investigate the effects of minocycline on the expression of selected transcriptional and translational profiles in the rat spinal cord following sciatic nerve (SNR) transection and microsurgical coaptation. The mRNA and protein expression levels of B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, major histocompatibility complex I (MHC I), tumor necrosis factor-α (TNF-α), activating transcription factor 3 (ATF3), vascular endothelial growth factor (VEGF), matrix metalloproteinase 9 (MMP9), and growth associated protein-43 (GAP-43) were monitored in the rat lumbar spinal cord following microsurgical reconstruction of the sciatic nerves and minocycline treatment. The present study used semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. As a PCR analysis of spinal cord tissue enabled the examination of the expression patterns of all cell types including glia, the motorneuron-like NSC-34 cell line was used to investigate expression level changes in motorneurons. As stressors, oxygen glucose deprivation (OGD) and lipopolysaccharide (LPS) treatment were performed. SNR did not induce significant degeneration of ventral horn motorneurons, whereas microglia activation and synaptic terminal retraction were detectable. All genes were constitutively expressed at the mRNA and protein levels in untreated spinal cord and control cells. SNR significantly increased the mRNA expression levels of all genes, albeit only temporarily. In all genes except MMP9 and GAP-43, the induction was seen ipsilaterally and contralaterally. The effects of minocycline were moderate. The expression levels of MMP9, TNF-α, MHC I, VEGF, and GAP-43 were reduced, whereas those of Bax and Bcl-2 were unaffected. OGD, but not LPS, was toxic for NSC-34 cells. No changes in the expression levels of Bax, caspase-3, MHC I or ATF3 were observed. These results indicated that motorneurons were not preferentially or solely responsible for SNR-mediated upregulation of these genes. MMP9, TNF-α, VEGF and Bcl-2 were stress-activated. These results suggest that a substantial participation of motorneurons in gene expression levels in vivo. Minocycline was also shown to have inhibitory effects. The nuclear factor-κB signalling pathway may be a possible target of minocycline.

Damage to the optic chiasm in myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis mice

Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T₂-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T₂-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis.

Matrix metalloproteinases, new insights into the understanding of neurodegenerative disorders

Matrix metalloproteinases (MMPs) are a subfamily of zinc-dependent proteases that are responsible for degradation and remodeling of extracellular matrix proteins. The activity of MMPs is tightly regulated at several levels including cleavage of prodomain, allosteric activation, compartmentalization and complex formation with tissue inhibitor of metalloproteinases (TIMPs). In the central nervous system (CNS), MMPs play a wide variety of roles ranging from brain development, synaptic plasticity and repair after injury to the pathogenesis of various brain disorders. Following general discussion on the domain structure and the regulation of activity of MMPs, we emphasize their implication in various brain disorder conditions such as Alzheimer’s disease, multiple sclerosis, ischemia/reperfusion and Parkinson’s disease. We further highlight accumulating evidence that MMPs might be the culprit in Parkinson’s disease (PD). Among them, MMP-3 appears to be involved in a range of pathogenesis processes in PD including neuroinflammation, apoptosis and degradation of α-synuclein and DJ-1. MMP inhibitors could represent potential novel therapeutic strategies for treatments of neurodegenerative diseases.

Disease-modifying treatments for progressive multiple sclerosis

The last 20 years have seen major progress in the treatment of relapsing-remitting multiple sclerosis (RRMS) using a variety of drugs targeting immune dysfunction. In contrast, all clinical trials of such agents in primary progressive multiple sclerosis (PPMS) have failed and there is limited evidence of their efficacy in secondary progressive disease. Evolving concepts of the complex interplay between inflammatory and neurodegenerative processes across the course of multiple sclerosis (MS) may explain this discrepancy. This paper will provide an up-to-date overview of the rationale and results of the published clinical trials that have sought to alter the trajectory of both primary and secondary MS, considering studies involving drugs with a primary immune target and also those aiming for neuroprotection. Future areas of study will be discussed, building on these results combined with the experience of treating RRMS and new concepts emerging from laboratory science and animal models.

The significance of matrix metalloproteinases in the immunopathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). The major pathological outcomes of the disease are the loss of blood-brain barrier (BBB) integrity and the development of reactive astrogliosis and MS plaque. For the disease to occur, the non-resident cells must enter into the immune-privileged CNS through a breach in the relatively impermeable BBB. It has been demonstrated that matrix metalloproteinases (MMPs) play an important role in the immunopathogenesis of MS, in part through the disruption of the BBB and the recruitment of inflammatory cells into the CNS. Moreover, MMPs can also enhance the cleavage of myelin basic protein (MBP) and the demyelination process. Regarding the growing data on the roles of MMPs and their tissue inhibitors (TIMPs) in the pathogenesis of MS, this review discusses the role of different types of MMPs, including MMP-2, -3, -7, -9, -12 and -25, in the immunopathogenesis and treatment of MS.

Neuroprotection in multiple sclerosis: a therapeutic approach

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that is pathologically characterized by inflammatory demyelination and neurodegeneration. Axonal damage, along with neuronal loss, occurs from disease onset and may lead to progressive and permanent disability. In contrast with the inflammatory pathways, the molecular mechanisms leading to MS neurodegeneration remain largely elusive. With improved understanding of these mechanisms, new potential therapeutic targets for neuroprotection have emerged. We review the current understanding of neurodegenerative processes at play in MS and discuss potential outcome measures and targets for neuroprotection trials.

Effective combination of human bone marrow mesenchymal stem cells and minocycline in experimental autoimmune encephalomyelitis mice

INTRODUCTION

Multiple sclerosis (MS) is the most common inflammatory demyelinating disorder of the central nervous system (CNS). Minocycline ameliorates the clinical severity of MS and exhibits antiinflammatory, neuroprotective activities, and good tolerance for long-term use, whereas it is toxic to the CNS. Recently, the immunomodulation and neuroprotection capabilities of human bone marrow mesenchymal stem cells (hBM-MSCs) were shown in experimental autoimmune encephalomyelitis (EAE). In this study, we evaluated whether the combination of hBM-MSCs and a low-dose minocycline could produce beneficial effects in EAE mice.

METHODS

The sensitivity of hBM-MSCs to minocycline was determined by an established cell-viability assay. Minocycline-treated hBM-MSCs were also characterized with flow cytometry by using MSC surface markers and analyzed for their multiple differentiation capacities. EAE was induced in C57BL/6 mice by using immunization with MOG35-55. Immunopathology assays were used to detect the inflammatory cells, demyelination, and neuroprotection. Interferon gamma (IFN-γ)/tumor necrosis factor alpha (TNF-α) and interleukin-4 (IL-4)/interleukin-10 (IL-10), the hallmark cytokines that direct Th1 and Th2 development, were detected with enzyme-linked immunosorbent assay (ELISA). terminal dUTP nick-end labeling (TUNEL) staining was performed to elucidate the cell apoptosis in the spinal cords of EAE mice.

RESULTS

Minocycline did not affect the viability, surface phenotypes, or differentiation capacity of hBM-MSCs, while minocycline affected the viability of astrocytes at a high dose. In vivo efficacy experiments showed that combined treatment, compared to the use of minocycline or hBM-MSCs alone, resulted in a significant reduction in clinical scores, along with attenuation of inflammation, demyelination, and neurodegeneration. Moreover, the combined treatment with hBM-MSCs and minocycline enhanced the immunomodulatory effects, which suppressed proinflammatory cytokines (IFN-γ, TNF-α) and conversely increased anti-inflammatory cytokines (IL-4, IL-10). In addition, TUNEL staining also demonstrated a significant decrease of the number of apoptotic cells in the combined treatment compared with either treatment alone.

CONCLUSIONS

The combination of hBM-MSCs and minocycline provides a novel experimental protocol to enhance the therapeutic effects in MS.

Combinatorial Effect of Metformin and Lovastatin Impedes T-cell Autoimmunity and Neurodegeneration in Experimental Autoimmune Encephalomyelitis

Multiple Sclerosis (MS) is an incurable central nervous system (CNS) demyelinating disease affecting several million people worldwide. Due to the multifactorial and complex pathology of MS, FDA approved drugs often show limited efficacy inpatients. We earlier documented that both lovastatin (cholesterol lowering drug) and metformin (anti-diabetic drug) attenuate experimental autoimmune encephalomyelitis (EAE), a widely used model of MS via different mechanisms of action. Since combination therapy of two or more agents has advantage over monotherapy, we here assessed the therapeutic efficacy of metformin and lovastatin combination in EAE. We found that suboptimal doses of these drugs in combination had additive effect to attenuate established EAE in treated animals than their individual treatments. Histological, immunohistochemistry and western blotting analyses revealed that the observed demyelination and axonal loss as evident from reduced levels of myelin and neurofilament proteins in the spinal cords of EAE animals were attenuated by treatment with these drugs in combination. Accordingly, the observed infiltration of myelin reactive T cells (CD4 and CD8) and macrophages (CD68) as well as the increased expression of their signatory cytokines in the spinal cords of EAE animals were attenuated by this regimen as revealed by enzyme-linked immune-sorbent assay and real-time PCR analyses. In the periphery, this regimen biased the class of elicited anti-myelin basic protein immunoglobulins from IgG2a to IgG1 and IgG2b, suggesting a Th1 to Th2 shift which was further supported by the increased expression of their signatory cytokines in EAE animals. Taken together, these data imply that metformin and lovastatin combination attenuates T-cell autoimmunity and neurodegeneration in treated EAE animals thereby suggesting that the oral administration of these FDA approved drugs in combination has potential to limit MS pathogenesis.

A sphingosine-1-phosphate receptor 1-directed agonist reduces central nervous system inflammation in a plasmacytoid dendritic cell-dependent manner

Gradients of the sphingolipid sphingosine-1-phosphate (S1P) are responsible for the egress of lymphocytes from lymph nodes by activating the S1P1 receptor expressed on the surface of lymphocytes. Small molecule drugs that downregulate S1P receptors induce the sequestration of lymphocytes within lymph nodes, thus preventing lymphocytes from accessing sites of inflammation. In particular, FTY720, a pan-S1P receptor agonist, has been efficacious in the treatment of multiple sclerosis as well as its animal model, experimental autoimmune encephalomyelitis (EAE), by virtue of its ability to restrain lymphocytes within the lymph nodes, thus precluding their migration into the CNS. However, multiple leukocyte subsets express S1P receptors of varying types, and although it is beneficial to prevent transmigration of proinflammatory lymphocytes into the CNS, allowing access of regulatory leukocyte subsets to the CNS is desirable. In this study, we show that an S1P1-specific agonist (AUY954) is clinically efficacious in ameliorating pre-established EAE in SJL/J mice. Efficacy of AUY954 correlated with a reduction of lymphocytes in the CNS, but access of plasmacytoid dendritic cells (pDCs) to the CNS was unimpaired, and the presence of pDCs was found to be an important cofactor in mediating the clinical efficacy of AUY954. These results indicate that pDCs are important in quieting autoimmune responses during EAE, and that trafficking inhibitors that are permissive for pDC accumulation in the CNS may be of therapeutic value for the treatment of multiple sclerosis.

Experimental autoimmune encephalomyelitis (EAE) as a model for multiple sclerosis (MS)

Experimental autoimmune encephalomyelitis (EAE) is the most commonly used experimental model for the human inflammatory demyelinating disease, multiple sclerosis (MS). EAE is a complex condition in which the interaction between a variety of immunopathological and neuropathological mechanisms leads to an approximation of the key pathological features of MS: inflammation, demyelination, axonal loss and gliosis. The counter-regulatory mechanisms of resolution of inflammation and remyelination also occur in EAE, which, therefore can also serve as a model for these processes. Moreover, EAE is often used as a model of cell-mediated organ-specific autoimmune conditions in general. EAE has a complex neuropharmacology, and many of the drugs that are in current or imminent use in MS have been developed, tested or validated on the basis of EAE studies. There is great heterogeneity in the susceptibility to the induction, the method of induction and the response to various immunological or neuropharmacological interventions, many of which are reviewed here. This makes EAE a very versatile system to use in translational neuro- and immunopharmacology, but the model needs to be tailored to the scientific question being asked. While creating difficulties and underscoring the inherent weaknesses of this model of MS in straightforward translation from EAE to the human disease, this variability also creates an opportunity to explore multiple facets of the immune and neural mechanisms of immune-mediated neuroinflammation and demyelination as well as intrinsic protective mechanisms. This allows the eventual development and preclinical testing of a wide range of potential therapeutic interventions.

The prospects of minocycline in multiple sclerosis

Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system (CNS). Although there are several approved drugs for MS, not all patients respond optimally to these drugs. More effective, well-tolerated therapeutic strategies for MS are necessary, either through the development of new medication or combination of existing ones. Minocycline is a traditional antibiotic with profound anti-inflammatory and neuroprotective effects and good tolerance for long-term use. The encouraging results from the animal model and clinical experiments on minocycline make it a promising candidate for MS treatment whether used alone or combined with other drugs. In this review, we summarized the pharmacological actions of minocycline and focused on its therapeutic effects and safety in experimental autoimmune encephalomyelitis (EAE) and MS. The data obtained here showed that minocycline would be an effective and safe therapy for MS.

Centrally administered pertussis toxin inhibits microglia migration to the spinal cord and prevents dissemination of disease in an EAE mouse model

Background

Experimental autoimmune encephalomyelitis (EAE) models are important vehicles for studying the effect of infectious elements such as Pertussis toxin (PTx) on disease processes related to acute demyelinating encephalomyelitis (ADEM) or multiple sclerosis (MS). PTx has pleotropic effects on the immune system. This study was designed to investigate the effects of PTx administered intracerebroventricularly (icv) in preventing downstream immune cell infiltration and demyelination of the spinal cord.

Methods and Findings

EAE was induced in C57BL/6 mice with MOG_35–55. PTx icv at seven days post MOG immunization resulted in mitigation of clinical motor symptoms, minimal T cell infiltration, and the marked absence of axonal loss and demyelination of the spinal cord. Integrity of the blood brain barrier was compromised in the brain whereas spinal cord BBB integrity remained intact. PTx icv markedly increased microglia numbers in the brain preventing their migration to the spinal cord. An in vitro transwell study demonstrated that PTx inhibited migration of microglia.

Conclusion

Centrally administered PTx abrogated migration of microglia in EAE mice, limiting the inflammatory cytokine milieu to the brain and prevented dissemination of demyelination. The effects of PTx icv warrants further investigation and provides an attractive template for further study regarding the pleotropic effects of infectious elements such as PTx in the pathogenesis of autoimmune disorders.

Preclinical studies of methylthioadenosine for the treatment of multiple sclerosis

BACKGROUND

Methylthioadenosine (MTA) is a natural metabolite with immunomodulatory properties. MTA improves the clinical course and pathology of the animal model of multiple sclerosis, even when therapy is started after disease onset.

OBJECTIVE

Our aim was to compare the efficacy of MTA in ameliorating experimental autoimmune encephalomyelitis (EAE) compared with first line approved therapies, to develop an oral formulation of MTA and to assess its pharmacokinetic profile.

METHODS

EAE was induced in C57BL/6 mice by immunization with MOG(35-55) peptide in Freund's Adjuvant. Animals were treated with MTA, interferon-beta or glatiramer acetate starting the day of immunization and the clinical score was collected blind. Pharmacokinetic studies were performed in Sprague Dawley rats by administering MTA by intraperitoneal injection and orally, and collecting blood at different intervals. MTA levels were measured by high-performance liquid chromatography.

RESULTS

We found that MTA ameliorated EAE in a dose-response manner. Moreover, the highest dose of MTA (60 mg/kg) was more efficacious than mouse interferon-beta or glatiramer acetate. We developed a salt of MTA for oral administration, with similar dose-response effect in the EAE model. Combination therapy assays between MTA and interferon-beta or glatiramer acetate were more effective than the individual therapies. Finally, oral MTA half-life was 20 min, with a C(max) of 80 mg/L and without signs of obvious toxicity (animal death, behavioural changes, liver enzymes).

CONCLUSIONS

In the EAE model MTA is more efficacious than first line therapies for multiple sclerosis, with a dose- response effect and higher efficacy when combined with interferon-beta or glatiramer acetate. Oral MTA was also effective in the animal model of multiple sclerosis.

Matrix metalloproteinases, synaptic injury, and multiple sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system in which immune mediated damage to myelin is characteristic. For an overview of this condition and its pathophysiology, please refer to one of many excellent published reviews (Sorensen and Ransohoff, 1998; Weiner, 2009). To follow, is a discussion focused on the possibility that synaptic injury occurs in at least a subset of patients, and that matrix metalloproteinases (MMPs) play a role in such.

Role of gut commensal microflora in the development of experimental autoimmune encephalomyelitis

Mucosal tolerance has been considered a potentially important pathway for the treatment of autoimmune disease, including human multiple sclerosis and experimental conditions such as experimental autoimmune encephalomyelitis (EAE). There is limited information on the capacity of commensal gut bacteria to induce and maintain peripheral immune tolerance. Inbred SJL and C57BL/6 mice were treated orally with a broad spectrum of antibiotics to reduce gut microflora. Reduction of gut commensal bacteria impaired the development of EAE. Intraperitoneal antibiotic-treated mice showed no significant decline in the gut microflora and developed EAE similar to untreated mice, suggesting that reduction in disease activity was related to alterations in the gut bacterial population. Protection was associated with a reduction of proinflammatory cytokines and increases in IL-10 and IL-13. Adoptive transfer of low numbers of IL-10-producing CD25(+)CD4(+) T cells (>75% FoxP3(+)) purified from cervical lymph nodes of commensal bacteria reduced mice and in vivo neutralization of CD25(+) cells suggested the role of regulatory T cells maintaining peripheral immune homeostasis. Our data demonstrate that antibiotic modification of gut commensal bacteria can modulate peripheral immune tolerance that can protect against EAE. This approach may offer a new therapeutic paradigm in the treatment of multiple sclerosis and perhaps other autoimmune conditions.

Combination therapy of lovastatin and rolipram provides neuroprotection and promotes neurorepair in inflammatory demyelination model of multiple sclerosis

Drug combination therapies for central nervous system (CNS) demyelinating diseases including multiple sclerosis (MS) are gaining momentum over monotherapy. Over the past decade, both in vitro and in vivo studies established that statins (HMG-CoA reductase inhibitors) and rolipram (phosphodiesterase-4 inhibitor; blocks the degradation of intracellular cyclic AMP) can prevent the progression of MS in affected individuals via different mechanisms of action. In this study, we evaluated the effectiveness of lovastatin (LOV) and rolipram (RLP) in combination therapy to promote neurorepair in an inflammatory CNS demyelination model of MS, experimental autoimmune encephalomyelitis (EAE). Combination treatment with suboptimal doses of these drugs in an established case of EAE (clinical disease score > or = 2.0) significantly attenuated the infiltration of inflammatory cells and protected myelin sheath and axonal integrity in the CNS. It was accompanied with elevated level of cyclic AMP and activation of its associated protein kinase A. Interestingly, combination treatment with these drugs impeded neurodegeneration and promoted neurorepair in established EAE animals (clinical disease score > or = 3.5) as verified by quantitative real-time polymerase chain reaction, immunohistochemistry and electron microscopic analyses. These effects of combination therapy were minimal and/or absent with either drug alone in these settings. Together, these data suggest that combination therapy with LOV and RLP has the potential to provide neuroprotection and promote neurorepair in MS, and may have uses in other related CNS demyelinating diseases.

The importance of NAD in multiple sclerosis

The etiology of multiple sclerosis (MS) is unknown but it manifests as a chronic inflammatory demyelinating disease in the central nervous system (CNS). During chronic CNS inflammation, nicotinamide adenine dinucleotide (NAD) concentrations are altered by (T helper) Th1-derived cytokines through the coordinated induction of both indoleamine 2,3-dioxygenase (IDO) and the ADP cyclase CD38 in pathogenic microglia and lymphocytes. While IDO activation may keep auto-reactive T cells in check, hyper-activation of IDO can leave neuronal CNS cells starving for extracellular sources of NAD. Existing data indicate that glia may serve critical functions as an essential supplier of NAD to neurons during times of stress. Administration of pharmacological doses of non-tryptophan NAD precursors ameliorates pathogenesis in animal models of MS. Animal models of MS involve artificially stimulated autoimmune attack of myelin by experimental autoimmune encephalomyelitis (EAE) or by viral-mediated demyelination using Thieler's murine encephalomyelitis virus (TMEV). The Wld(S) mouse dramatically resists razor axotomy mediated axonal degeneration. This resistance is due to increased efficiency of NAD biosynthesis that delays stress-induced depletion of axonal NAD and ATP. Although the Wld(S) genotype protects against EAE pathogenesis, TMEV-mediated pathogenesis is exacerbated. In this review, we contrast the role of NAD in EAE versus TMEV demyelinating pathogenesis to increase our understanding of the pharmacotherapeutic potential of NAD signal transduction pathways. We speculate on the importance of increased SIRT1 activity in both PARP-1 inhibition and the potentially integral role of neuronal CD200 interactions through glial CD200R with induction of IDO in MS pathogenesis. A comprehensive review of immunomodulatory control of NAD biosynthesis and degradation in MS pathogenesis is presented. Distinctive pharmacological approaches designed for NAD-complementation or targeting NAD-centric proteins (SIRT1, SIRT2, PARP-1, GPR109a, and CD38) are outlined towards determining which approach may work best in the context of clinical application.

Novel therapeutic strategies for multiple sclerosis--a multifaceted adversary

Therapeutic strategies for multiple sclerosis have radically changed in the past 15 years. Five regulatory-approved immunomodulatory agents are reasonably effective in the treatment of relapsing-remitting multiple sclerosis, and appear to delay the time to progression to disabling stages. Inhibiting disease progression remains the central challenge for the development of improved therapies. As understanding of the immunopathogenesis of multiple sclerosis has advanced, a number of novel potential therapeutics have been identified, and are discussed here. It has also become apparent that traditional views of multiple sclerosis simply as a CD4+ T-cell-mediated disease of the central nervous system are incomplete. The pathogenic role of other immune components such as the innate immune system, regulatory T cells, T helper 17 cells and B cells is reaching centre stage, opening up exciting avenues and novel potential targets to affect the natural course of multiple sclerosis.

Pilot study of minocycline in relapsing-remitting multiple sclerosis

BACKGROUND

Current multiple sclerosis (MS) treatment is only partially effective and not all patients respond well. The goal in this study was to evaluate minocycline for its safety, tolerability, and MRI impact as a potential therapy over 36 months after a three month run-in in ten relapsing-remitting (RR) MS patients.

METHODS

Clinical assessments were at three month intervals until six months, then at six month intervals. Three Tesla MRI was performed monthly during the run-in and first six months of treatment, then at 12, 24, and 36 months.

RESULTS

Treatment was safe and well tolerated. Annualized relapse rate was 1.2 during the run-in and 0.25 during treatment. The proportion of active scans was lower during the first six months of treatment (5.6%, p < 0.001) and during the extension (8.7%, p = 0.002) than during the run-in (47.5%). Consistent with these outcomes, mean T2 lesion volume remained stable over three years and percent brain volume change was reduced during year three (-0.37%) of minocycline treatment.

CONCLUSIONS

This trial is limited by small sample and no control group but suggests that minocycline is safe and potentially beneficial in RRMS. This supports further investigation of its efficacy.

Combined medication of lovastatin with rolipram suppresses severity of experimental autoimmune encephalomyelitis

Combinations of new medications or existing therapies are gaining momentum over monotherapy to treat central nervous system (CNS) demyelinating diseases including multiple sclerosis (MS). Recent studies established that statins (HMG-CoA reductase inhibitors) are effective in experimental autoimmune encephalomyelitis (EAE), an MS model and are promising candidates for future MS medication. Another drug, rolipram (phosphodiesterase-4 inhibitor) ameliorates the clinical severity of EAE via induction of various anti-inflammatory and neuroprotective activities. In this study, we tested whether combining the suboptimal doses of these drugs can suppress the severity of EAE. Prophylactic studies revealed that combined treatment with suboptimal doses of statins perform better than their individually administered optimal doses in EAE as evidenced by delayed clinical scores, reduced disease severity, and rapid recovery. Importantly, combination therapy suppressed the progression of disease in an established EAE case via attenuation of inflammation, axonal loss and demyelination. Combination treatment attenuated inflammatory T(H)1 and T(H)17 immune responses and induced T(H)2-biased immunity in the peripheral and CNS as revealed by serological, quantitative, and immunosorbant assay-based analyses. Moreover, the expansion of T regulatory (CD25(+)/Foxp3(+)) cells and self-immune tolerance was apparent in the CNS. These effects of combined drugs were reduced or minimal with either drug alone in this setting. In conclusion, our findings demonstrate that the combination of these drugs suppresses EAE severity and provides neuroprotection thereby suggesting that this pharmacological approach could be a better future therapeutic strategy to treat MS patients.

Combined treatment with atorvastatin and minocycline suppresses severity of EAE

Multiple sclerosis (MS) is the most common inflammatory demyelinating disorder of the central nervous system (CNS). An approach to improve MS treatment is to identify a rational combination of new medications or existing therapies that impact different aspects of the disease process. Statins are effective in the treatment of MS animal models and are promising candidates for future treatment. Minocycline ameliorates clinical severity of experimental autoimmune encephalomyelitis (EAE) and exhibits several anti-inflammatory and neuroprotective activities. In this study, we tested whether the combination of these two drugs could produce beneficial effects in EAE mice immunized with myelin oligodendrocyte protein (MOG). Our findings show that combined treatment, compared to using the medications alone, resulted in a significant reduction in disease severity, in both the acute and chronic phases of the disease, along with attenuation of inflammation, demyelination and axonal loss. Stereological analysis revealed that the combined treatment significantly guarded against neuroinflammation and neurodegeneration. Moreover, a significant suppression of anti-MOG antibody production in animals treated with the two medications was found. In conclusion, our findings prove that this combination of drugs is neuroprotective and suppresses the severity of EAE. Furthermore, this pharmacological approach appears to be promising as a future therapeutic strategy to control MS.

Delayed combinatorial treatment with flavopiridol and minocycline provides longer term protection for neuronal soma but not dendrites following global ischemia

We previously reported that delayed administration of the general cyclin-dependent kinase inhibitor flavopiridol following global ischemia provided transient neuroprotection and improved behavioral performance. However, it failed to provide longer term protection. In the present study, we investigate the ability of delayed flavopiridol in combination with delayed minocycline, another neuroprotectant to provide sustained protection following global ischemia. We report that a delayed combinatorial treatment of flavopiridol and minocycline provides synergistic protection both 2 and 10 weeks following ischemia. However, protected neurons in the hippocampal CA1 are synaptically impaired as assessed by electrophysio logical field potential recordings. This is likely because of the presence of degenerated processes in the CA1 even with combinatorial therapy. This indicates that while we have addressed one important pre-clinical parameter by dramatically improving long-term neuronal survival with delayed combinatorial therapy, the issue of synaptic preservation of protected neurons still exists. These results also highlight the important observation that protection does not always lead to proper function.

Efficacy of minocycline in patients with amyotrophic lateral sclerosis: a phase III randomised trial

BACKGROUND

Minocycline has anti-apoptotic and anti-inflammatory effects in vitro, and extends survival in mouse models of some neurological conditions. Several trials are planned or are in progress to assess whether minocycline slows human neurodegeneration. We aimed to test the efficacy of minocycline as a treatment for amyotrophic lateral sclerosis (ALS).

METHODS

We did a multicentre, randomised placebo-controlled phase III trial. After a 4-month lead-in phase, 412 patients were randomly assigned to receive placebo or minocycline in escalating doses of up to 400 mg/day for 9 months. The primary outcome measure was the difference in rate of change in the revised ALS functional rating scale (ALSFRS-R). Secondary outcome measures were forced vital capacity (FVC), manual muscle testing (MMT), quality of life, survival, and safety. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00047723.

FINDINGS

ALSFRS-R score deterioration was faster in the minocycline group than in the placebo group (-1.30 vs -1.04 units/month, 95% CI for difference -0.44 to -0.08; p=0.005). Patients on minocycline also had non-significant tendencies towards faster decline in FVC (-3.48 vs -3.01, -1.03 to 0.11; p=0.11) and MMT score (-0.30 vs -0.26, -0.08 to 0.01; p=0.11), and greater mortality during the 9-month treatment phase (hazard ratio=1.32, 95% CI 0.83 to 2.10; p=0.23) than did patients on placebo. Quality-of-life scores did not differ between the treatment groups. Non-serious gastrointestinal and neurological adverse events were more common in the minocycline group than in the placebo group, but these events were not significantly related to the decline in ALSFRS-R score.

INTERPRETATION

Our finding that minocycline has a harmful effect on patients with ALS has implications for trials of minocycline in patients with other neurological disorders, and for how potential neuroprotective agents are screened for use in patients with ALS.

Elevation of matrix metalloproteinases (MMPs) in multiple sclerosis and impact of immunomodulators

The matrix metalloproteinases (MMPs) are implicated in the pathology of multiple sclerosis (MS). This review summarizes the consequences of upregulation of MMP members in MS as well as in an animal model of the disease, experimental autoimmune encephalomyelitis (EAE). The pathogenic roles of MMPs are considered, especially in the transmigration of leukocytes into the CNS. We review the evidence that interferon-beta, an immunomodulator that is commonly used in MS, affects MMP expression in the disease. The potential of minocycline as a therapy in MS, based on its activity as an MMP inhibitor, is discussed. Besides affecting MMPs, minocycline may have other actions that help account for its possible utility in MS.

[Update on pathophysiologic and immunotherapeutic approaches for the treatment of multiple sclerosis]

Multiple sclerosis (MS) is a chronic disabling disease with significant implications for patients and society. The individual disease course is difficult to predict due to the heterogeneity of clinical presentation and of radiologic and pathologic findings. Although its etiology still remains unknown, the last decade has brought considerable understanding of the underlying pathophysiology of MS. In addition to its acceptance as a prototypic inflammatory autoimmune disorder, recent data reveal the importance of primary and secondary neurodegenerative mechanisms such as oligodendrocyte death, axonal loss, and ion channel dysfunction. The deepened understanding of its immunopathogenesis and the limited effectiveness of currently approved disease-modifying therapies have led to a tremendous number of trials investigating potential new drugs. Emerging treatments take into account the different immunopathological mechanisms and strategies, to protect against axonal damage and promote remyelination. This review provides a compilation of novel immunotherapeutic strategies and recently uncovered aspects of known immunotherapeutic agents. The pathogenetic rationale of these novel drugs for the treatment of MS and accompanying preclinical and clinical data are highlighted.

Systemic infections in multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). It has been suggested that viral and bacterial infections contribute to the pathogenesis of MS. This review will give an overview about the influence of viral and bacterial infections on MS and experimental autoimmune encephalomyelitis (EAE). It will focus on bacterial infections and will also emphasise therapeutic consequences such as the impact of antibiotic treatment on the course of EAE. In summary, a growing body of evidence suggests that systemic infections are a risk factor for the initiation of autoimmune processes including the induction of acute events in MS. Experimental and clinical data strongly suggest early treatment of bacterial infections in MS patients to avoid aggravation and relapse.

Combination therapies for multiple sclerosis: scientific rationale, clinical trials, and clinical practice

PURPOSE OF REVIEW

To outline the scientific rationale for combination therapy in multiple sclerosis and to discuss the evidence for combination treatment strategies from animal models and clinical trials of multiple sclerosis.

RECENT FINDINGS

Experiments conducted in experimental autoimmune encephalomyelitis have recently shown beneficial effects of numerous combination therapies. The combination of approved and experimental drugs and two or more experimental agents may positively impact clinical disease activity, inflammation within the central nervous system, and neurorepair. Clinical trials are currently underway to establish the therapeutic efficacy and safety of various combination therapies for multiple sclerosis patients.

SUMMARY

More effective therapies are needed to treat multiple sclerosis. There are good scientific rationales for the use of combination therapy in multiple sclerosis, and the pharmacologic principles for evaluating and understanding their actions are available. The evaluation of specific combination therapies in the controlled setting of clinical trials should be a priority in clinical multiple sclerosis research.

Multiple Sclerosis as A Painful Disease

Pain is a common problem of patients with multiple sclerosis (MS) and may be due to central/neuropathic or peripheral/somatic pathology. Rarely MS may present with pain, or pain may herald an MS exacerbation, such as in painful tonic spasms or Lhermitte's sign. In other patients, pain may become chronic as a long-term sequela of damage to nerve root entry zones (trigeminal neuralgia) or structures in central sensory pathways. Migraine headache may develop as a consequence of MS, and headache can also be a side effect of interferon treatment. The pathophysiology of pain in MS may be linked to certain plaque locations which disrupt the spinothalamic and quintothalamic pathways, abnormal impulses through motor axons, development of an acquired channelopathy in affected nerves, or involve glial cell inflammatory immune mechanisms. At this time, the treatment of pain in MS employs the use of antiepileptic drugs, muscle relaxers/antispasmodic agents, anti-inflammatory drugs, and nonpharmacological measures. Research concerning cannabis-based treatments shows promising results, and substances which block microglial or astrocytic involvement in pain processing are also under investigation.

Evolving Therapies For Multiple Sclerosis

The introduction of immunomodulatory and immunosuppressive agents for treatment of multiple sclerosis (MS) has forever altered the natural course of this incurable and disabling neurodegenerative disorder. Despite early diagnosis of relapsing-remitting MS and early initiation of therapy, patients still experience breakthrough relapses and progression of their underlying MS pathology. The imperfect effectiveness, side effects, and toxicity of these agents, emphasize the necessity for development of more effective medications with less adverse events. This chapter presents readers with the most current information on the nature, mechanism(s) of action, and side effects of the most promising experimental agents currently under clinical trials. Some of the agents now at different stages of clinical trial have emerged as both safe and promising. The understanding of MS etiology will lead to the development of increasingly specific, safer, and effective treatments for MS by neuroscientists and neurologists.

Magnetic resonance imaging of blood–spinal cord barrier disruption in mice with experimental autoimmune encephalomyelitis

Inflammation, demyelination, and blood-spinal cord barrier (BSB) breakdown occur in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. The purpose of this study was to evaluate the utility of MRI for detecting lesions and BSB disruption in vivo during EAE in the mouse lumbar spinal cord, to determine how MR features of BSB disruption change during the course of disease, and to relate such changes to clinical signs and histological features of disease. Following induction of EAE in C57BL/6 mice, contrast-enhanced (CE) T(1)-weighted MR images were acquired to detect BSB disruption in the lumbar spinal cord at the early stage of disease, at peak disease, and at remission, and T(2)-weighted images were obtained to monitor spinal cord morphology. Following imaging the spinal cords were assessed in situ for general features of inflammation, BSB leakage, activated macrophages/microglia, and demyelination. No focal lesions were evident on T(2)-weighted MR images. BSB disruption was greatest at the onset of signs of disease, and decreased progressively thereafter. Inflammation and demyelination were pronounced at the initial stage of disease and at peak disease, and were decreased at remission. Nonuniform contrast enhancement indicated that breakdown of the BSB occurred predominantly within the white matter (WM) of the spinal cord.

The neurotoxic effect of cuprizone on oligodendrocytes depends on the presence of pro-inflammatory cytokines secreted by microglia

In order to further characterize the still unknown mechanism of cuprizone-induced demyelination, we investigated its effect on rat primary oligodendroglial cell cultures. Cell viability was not significantly affected by this treatment. However, when concentrations of IFNgamma and/or TNFalpha having no deleterious effects per se on cell viability were added together with cuprizone, cell viability decreased significantly. In mitochondria isolated from cuprizone-treated glial cells, we observed a marked decrease in the activities of the various complexes of the respiratory chain, indicating a disruption of mitochondrial function. An enhancement in oxidant production was also observed in cuprizone and/or TNFalpha-treated oligodendroglial cells. In in vivo experiments, inhibition of microglial activation with minocycline prevented cuprizone-induced demyelination. Based on the above-mentioned results we suggest that these microglial cells appear to have a very active role in cuprizone-induced oligodendroglial cell death and demyelination, through the production and secretion of pro-inflammatory cytokines.