T cell independent mechanism for copolymer-1-induced neuroprotection

Causal ALS genes impact the MHC class II antigen presentation pathway

Mutations in RNA/DNA-binding proteins cause amyotrophic lateral sclerosis (ALS), but the underlying disease mechanisms remain unclear. Here, we report that a set of ALS-associated proteins, namely FUS, EWSR1, TAF15, and MATR3, impact the expression of genes encoding the major histocompatibility complex II (MHC II) antigen presentation pathway. Both subunits of the MHC II heterodimer, HLA-DR, are down-regulated in ALS gene knockouts/knockdown in HeLa and human microglial cells, due to loss of the MHC II transcription factor CIITA. Importantly, hematopoietic progenitor cells (HPCs) derived from human embryonic stem cells bearing the FUSR495X mutation and HPCs derived from C9ORF72 ALS patient induced pluripotent stem cells also exhibit disrupted MHC II expression. Given that HPCs give rise to numerous immune cells, our data raise the possibility that loss of the MHC II pathway results in global failure of the immune system to protect motor neurons from damage that leads to ALS.

Repurposing MS immunotherapies for CIDP and other autoimmune neuropathies: unfulfilled promise or efficient strategy?

Despite advances in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and other common autoimmune neuropathies (AN), still-many patients with these diseases do not respond satisfactorily to the available treatments. Repurposing of disease-modifying therapies (DMTs) from other autoimmune conditions, particularly multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), is a promising strategy that may accelerate the establishment of novel treatment choices for AN. This approach appears attractive due to homologies in the pathogenesis of these diseases and the extensive post-marketing experience that has been gathered from treating MS and NMOSD patients. The idea is also strengthened by a number of studies that explored the efficacy of DMTs in animal models of AN but also in some CIDP patients. We here review the available preclinical and clinical data of approved MS therapeutics in terms of their applicability to AN, especially CIDP. Promising therapeutic approaches appear to be B cell-directed and complement-targeting strategies, such as anti-CD20/anti-CD19 agents, Bruton's tyrosine kinase inhibitors and anti-C5 agents, as they exert their effects in the periphery. This is a major advantage because, in contrast to MS, their action in the periphery is sufficient to exert significant immunomodulation.

Beneficial Effect of Melatonin Alone or in Combination with Glatiramer Acetate and Interferon β-1b on Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a relevant animal model of multiple sclerosis (MS). Oxidative stress and chronic inflammation play a major role in the pathogenesis of MS and EAE. Melatonin, a neurohormone, has potent anti-inflammatory properties. The aim of our study was to assess the therapeutic properties of melatonin alone or in combination with interferon β-1b (IFNβ-1b) or glatiramer acetate (GA) on EAE. EAE was induced in male Sprague-Dawley rats with an intraperitoneal injection of a homogenate of spinal cord and pig brain. At day 10 post immunization, rats were euthanized, and their brains were immediately excised and processed to measure oxidative stress markers and membrane fluidity. In addition, proinflammatory cytokines were quantified in plasma. Melatonin alone or in combination with GA and IFNβ-1b inhibited the disease process of EAE and the synthesis of proinflammatory cytokines, caused a significant decrement in oxidative stress markers, and preserved the membrane fluidity in the motor cortex, midbrain, and spinal cord. The cumulative index score was significantly reduced in EAE rats treated with melatonin alone or in combination with GA and IFNβ-1b. In conclusion, our findings provide preclinical evidence for the use of melatonin as an adjuvant therapeutic treatment for MS.

Macrophage reprogramming for therapy

Dysfunction of the immune system underlies a plethora of human diseases, requiring the development of immunomodulatory therapeutic intervention. To date, most strategies employed have been focusing on the modification of T lymphocytes, and although remarkable improvement has been obtained, results often fall short of the intended outcome. Recent cutting-edge technologies have highlighted macrophages as potential targets for disease control. Macrophages play central roles in development, homeostasis and host defence, and their dysfunction and dysregulation have been implicated in the onset and pathogenesis of multiple disorders including cancer, neurodegeneration, autoimmunity and metabolic diseases. Recent advancements have led to a greater understanding of macrophage origin, diversity and function, in both health and disease. Over the last few years, a variety of strategies targeting macrophages have been developed and these open new therapeutic opportunities. Here, we review the progress in macrophage reprogramming in various disorders and discuss the potential implications and challenges for macrophage-targeted approaches in human disease.

12-months prospective Pentraxin-3 and metabolomic evaluation in multiple sclerosis patients treated with glatiramer acetate

BACKGROUND

Pentraxin-3 (PTX-3) is involved in acute immunological responses and it is a pro-inflammatory protein and a novel biomarker of inflammatory diseases. It is demonstrated that PTX-3 is higher in cerebrospinal fluid (CSF) of aggressive Multiple Sclerosis (MS). Metabolomics, the identification of small endogenous molecules, offers a molecular profile of MS. Glatiramer acetate (GA) is a widely used treatment for (MS) but its mechanism of action is not completely defined. The aim of our study is to analyze PTX-3 and metabolomic profile in MS patients compared to controls and to investigate the effect of GA on PXT-3 and metabolic molecules during treatment in responder and not responder MS patients.

METHODS

28 unrelated MS patients and 27 age-and sex-matched controls were recruited. In serum, PTX-3 levels were measured by ELISA and Metabolomic panel was evaluated trough Nuclear Magnetic Resonance (NMR). According to clinical practice patients started GA treatment; PTX-3 and metabolomic identification were performed before and during treatment. Responders to treatment were identified if no evidence of instrumental, clinical relapses and disability progression (NEDA) occurred during follow up.

RESULTS

Serum PTX-3 levels were higher in MS patients compared to matched controls (7,85 ± 2,19 vs 6,20 ± 1,63 ng/ml) (p = 0,03); metabolomic evaluation shows higher levels of lactate and lower levels of valine, tyrosine and tryptophan in MS patients compared to controls. During therapy, PTX-3 levels have been reduced statistically significant (p = 0,001) at six months and one year of treatment. After one year, of the twenty patients that completed the study, 55% were considered fully responders to treatment; in these patients the mean reduction of PTX-3 at one year was higher respect to not responders (-3,82 ± 1,24 ng/ml vs -2,32 ± 1,03 ng/ml p = 0,02) and we observed a higher reduction of lactate, tyrosine and hypoxanthine and an increase of hydroxyproline and ADP as well as of three oxidative phosphorylation markers, citrulline, ornithine and tryptophan approaching the metabolic profile of healthy subjects.

DISCUSSION AND CONCLUSIONS

We demonstrated a metabolomic imbalance with mitochondrial dysfunction detected by higher levels of lactate and lower levels of tryptophan, tyrosine and valine in MS patients compared to healthy controls. The reduction of PTX-3 levels and the restoring of mitochondrial function, reducing oxidative stress by GA, allows to identify responder patients. Further and larger studies are needed to understand the predictive role of PTX-3 and metabolomic pattern in the identification of responder patients to GA.

Assessing the Similarity between Random Copolymer Drug Glatiramer Acetate by Using LC-MS Data Coupling with Hypothesis Testing

The full characterization of nonbiological complex drugs (NBCDs) is not possible, but analytical approaches are of urgent need to evaluate the similarity between different lots and compare with their follow-up versions. Here, we propose a hypothesis testing-based approach to assess the similarity/difference between random amino acid copolymer drugs using liquid chromatography mass spectrometry (LC-MS) analysis. Two glatiramer acetate (GA) drugs, commercially available Copaxone and in-house synthesized SPT, and a negative control were digested by Lys-C and followed by HILIC-MS analysis. After retention time alignment and feature identification, 1627 features matched to m/z values in an elemental composition database were considered as derived from active drug ingredients. A hypothesis testing approach, the sum of squared deviations test, was developed to process high-dimensional data derived from LC-MS spectra. The feasibility of this approach was first demonstrated by testing 5 versus 5 lots of Copaxone and Copaxone versus SPT, which suggested a significant similarity by obtaining the estimated 95th percentile of the distribution of the estimator (ρ̂_(95%)) at 0.0056 (p-value = 0.0026) and 0.0026 (p-value < 0.0001), respectively. In contrast, the ρ̂ was 0.036 (p-value = 1.00), while comparing Copaxone and the negative control, implying a lack of similarity. We further synthesized nine stable isotope-labeled peptides to validate the proposed amino acid sequences in the database, demonstrating the correctness in sequence identification. The quantitation variations in our analytical procedures were determined to be 6.8-7.7%. This approach was found to have a great potential for evaluating the similarity between generic NBCDs and listed reference drugs, as well as to monitor the lot-to-lot variation.

The Severity of Spinal Cord Injury Determines the Inflammatory Gene Expression Pattern after Immunization with Neural-Derived Peptides

Previous studies revealed that the intensity of spinal cord injury (SCI) plays a key role in the therapeutic effects induced by immunizing with neural-derived peptides (INDP), as severe injuries abolish the beneficial effects induced by INDP. In the present study, we analyzed the expression of some inflammation-related genes (IL6, IL12, IL-1β, IFNɣ, TNFα, IL-10, IL-4, and IGF-1) by quantitative PCR in rats subjected to SCI and INDP. We investigated the expression of these genes after a moderate or severe contusion. In addition, we evaluated the effect of INDP by utilizing two different peptides: A91 and Cop-1. After moderate injury, both A91 and Cop-1 elicited a pattern of genes characterized by a significant reduction of IL6, IL1β, and TNFα but an increase in IL10, IL4, and IGF-1 expression. There was no effect on IL-12 and INFɣ. In contrast, the opposite pattern was observed when rats were subjected to a severe spinal cord contusion. Immunization with either peptide caused a significant increase in the expression of IL-12, IL-1β, IFNɣ (pro-inflammatory genes), and IGF-1. There was no effect on IL-4 and IL-10 compared to controls. After a moderate SCI, INDP reduced pro-inflammatory gene expression and generated a microenvironment prone to neuroprotection. Nevertheless, severe injury elicits the expression of pro-inflammatory genes that could be aggravated by INDP. These findings correlate with our previous results demonstrating that severe injury inhibits the beneficial effects of protective autoimmunity.

Role of Oligodendrocyte Dysfunction in Demyelination, Remyelination and Neurodegeneration in Multiple Sclerosis

Oligodendrocytes (OLs) are the myelinating cells of the central nervous system (CNS) during development and throughout adulthood. They result from a complex and well controlled process of activation, proliferation, migration and differentiation of oligodendrocyte progenitor cells (OPCs) from the germinative niches of the CNS. In multiple sclerosis (MS), the complex pathological process produces dysfunction and apoptosis of OLs leading to demyelination and neurodegeneration. This review attempts to describe the patterns of demyelination in MS, the steps involved in oligodendrogenesis and myelination in healthy CNS, the different pathways leading to OLs and myelin loss in MS, as well as principles involved in restoration of myelin sheaths. Environmental factors and their impact on OLs and pathological mechanisms of MS are also discussed. Finally, we will present evidence about the potential therapeutic targets in re-myelination processes that can be accessed in order to develop regenerative therapies for MS.

Metabolic response to glatiramer acetate therapy in multiple sclerosis patients

Glatiramer acetate (GA; Copaxone) is a random copolymer of glutamic acid, lysine, alanine, and tyrosine used for the treatment of patients with multiple sclerosis (MS). Its mechanism of action has not been already fully elucidated, but it seems that GA has an immune-modulatory effect and neuro-protective properties. Lymphocyte mitochondrial dysfunction underlines the onset of several autoimmune disorders. In MS first diagnosis patients, CD4⁺, the main T cell subset involved in the pathogenesis of MS, undergo a metabolic reprogramming that consist in the up-regulation of glycolysis and in the down-regulation of oxidative phosphorylation. Currently, no works exist about CD4⁺ T cell metabolism in response to GA treatment. In order to provide novel insight into the potential use of GA in MS treatment, blood samples were collected from 20 healthy controls (HCs) and from 20 RR MS patients prior and every 6 months during the 12 months of GA administration. GA treated patients' CD4⁺ T cells were compared with those from HCs analysing their mitochondrial activity through polarographic and enzymatic methods in association with their antioxidant status, through the analysis of SOD, GPx and CAT activities. Altogether, our findings suggest that GA is able to reduce CD4⁺ T lymphocytes' dysfunctions by increasing mitochondrial activity and their response to oxidative stress.

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GA is able to reduce CD4 + T cell's dysfunctions in MS patients;

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A CD4 + T cell metabolic response in GA treated patients is proposed;

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Metabolic response relies on changes in mitochondrial activity and in antioxidative status.

Expression of brain-derived neurotrophic factor in astrocytes - Beneficial effects of glatiramer acetate in the R6/2 and YAC128 mouse models of Huntington's disease

Glatiramer acetate (GA) is a FDA-approved drug which is licensed for the treatment of relapsing-remitting multiple sclerosis and which may exert neuroprotective effects via brain-derived neurotrophic factor (BDNF). In this study, we investigate effects of GA on BDNF expression especially in astrocytes in vitro and in vivo in brains of R6/2 and YAC128 transgenic mouse models of Huntington's disease (HD) where a pathogenic role of astroglial cells has recently been shown. We show that GA increases the expression of functionally active BDNF in astrocyte culture and in astrocytes of GA treated HD mice. In the brains of these mice, GA decreases neurodegeneration and restores BDNF levels. The beneficial effect of GA in R6/2 mice also comprises reduced weight loss and prolonged life span and, for both models, also improved motor performance. Further studies with this safe and effective drug in HD are warranted.

Pharmacologic Treatment of Rett Syndrome With Glatiramer Acetate

BACKGROUND

Rett syndrome (RTT) is a severe neurological disease that primarily affects females. The level of brain derived neurotropic factor (BDNF) expression directly correlates with the severity of RTT related symptoms. Because Glatiramer acetate (GA) stimulates secretion of BDNF in the brain, we conducted the study with the objective to assess its efficacy in improving gait velocity cognition, respiratory function, electroencephalographic findings, and quality of life in patients with RTT.

METHODS

Phase two, open label, single center trial.

INCLUSION CRITERIA

ambulatory girls with genetically confirmed RTT, 10 years or older. Pre- and post-treatment measures were compared using the non-parametric Wilcoxon signed rank sum test and paired t-tests.

RESULTS

Ten patients were enrolled and completed the trial. Gait velocity improved significantly (improvement range 13%-95%, p=0.03 for both tests) and emerged as an especially valuable outcome measure with excellent test- retest reliability of the 2 trials within sessions (intraclass correlation coefficient=0.94). Memory, and the breath holding index also improved significantly (p≤0.03). Epileptiform discharges decreased in all four patients who had them at baseline. There was a trend towards improved quality of life, which did not reach statistical significance.

CONCLUSIONS

This prospective open-label trial provides important preliminary information related to the efficacy of GA in improving gait velocity in female patients with RTT who are 10 years or older. The results of this trial justify the need for larger scale controlled trials of GA as well as provide a template for assessing the efficacy of other interventions in RTT.

Further understanding of the immunopathology of multiple sclerosis: impact on future treatments

INTRODUCTION

The understanding of the immunopathogenesis of multiple sclerosis (MS) has expanded with more research into T-cell subtypes, cytokine contributors, B-cell participation, mitochondrial dysfunction, and more. Treatment options have rapidly expanded with three relatively recent oral therapy alternatives entering the arena.

AREAS COVERED

In the following review, we discuss current mechanisms of immune dysregulation in MS, how they relate to current treatments, and the impact these findings will have on the future of therapy. Expert commentary: The efficacy of these medications and understanding their mechanisms of actions validates the immunopathogenic mechanisms thought to underlie MS. Further research has exposed new targets, while new promising therapies have shed light on new aspects into the pathophysiology of MS.

[A place of first-line drugs in treatment of multiple sclerosis]

A rapidly changing set of drugs for treatment of multiple sclerosis (MS) leads to the necessity of searching for predictors of their efficacy. Understanding of pathogenetic processes in MS and mechanisms of action of different drugs play an important role in the search for markers of potential responders. The author analyses the presently accumulated information on the original drug copaxone (glatiramer acetate) including current concepts on the mechanism of action, long-term safety and efficacy. Data on the frequency and significance of adverse effects during treatment with glatiramer acetate as well as on the influence of the drug on pregnancy, postpartum course of MS and development of the infant who received glatiramer acetate prenatally compared to other disease-modifying drugs are presented.

Glatiramer acetate guards against rapid memory decline during relapsing-remitting experimental autoimmune encephalomyelitis

Cognitive decline presents a therapeutic challenge for patients with multiple sclerosis (MS), a disease characterized by recurrent autoimmune demyelination and by progressive CNS degeneration. Glatiramer acetate (GA, also known as Copolymer 1, Cop-1, or Copaxone), commonly used to treat MS, reduces the frequency of relapses; it has both anti-inflammatory and neuroprotective properties. However, clinical trials have not definitively shown that GA improves cognitive impairment during MS. Using an in vivo animal model of autoimmune demyelination, i.e., relapsing-remitting experimental autoimmune encephalomyelitis (EAE), we tested short-term memory in EAE mice (EAE), in EAE mice treated with GA for 10 days starting at the time of immunization (EAE + GA), and in age-matched healthy, naïve mice (Naïve). Short-term memory was assessed using the cross-maze test at 10, 20, and 30 days post-immunization (d.p.i.); data were analyzed at each time point and over time. At 10 d.p.i., EAE and EAE + GA mice had better memory function than Naïve mice. However, at the later time points, EAE mice had a steep negative slope of memory function (indicating decline), whereas EAE + GA mice had a flatter, less-negative slope of memory function. Notably, the memory function of EAE mice significantly decreased over time compared with that of Naïve mice, indicating that EAE had a negative impact on cognitive ability. In contrast, there was no statistically significant difference between the slopes of memory function in mice with EAE treated with GA versus Naïve mice, which revealed effective, albeit partial, protection by GA treatment against progressive memory decline during EAE disease. Of particular interest, although EAE mice had memory decline over 30 d.p.i., their clinical disease scores improved during that time. Thus, our results suggest that EAE mice had a significant progressive memory decline and that GA, administered at the time of immunization, partially guards against rapid memory decline.

Lymphocytes and autoimmunity after spinal cord injury

Over the past 15 years an immense amount of data has accumulated regarding the infiltration and activation of lymphocytes in the traumatized spinal cord. Although the impact of the intraspinal accumulation of lymphocytes is still unclear, modulation of the adaptive immune response via active and passive vaccination is being evaluated for its preclinical efficacy in improving the outcome for spinal-injured individuals. The complexity of the interaction between the nervous and the immune systems is highlighted in the contradictions that appear in response to these modulations. Current evidence regarding augmentation and inhibition of the adaptive immune response to spinal cord injury is reviewed with an aim toward reconciling conflicting data and providing consensus issues that may be exploited in future therapies. Opportunities such an approach may provide are highlighted as well as the obstacles that must be overcome before such approaches can be translated into clinical trials.

Immunomodulation neuroprotection and remyelination - the fundamental therapeutic effects of glatiramer acetate: a critical review

Multiple sclerosis (MS) is a multifaceted heterogeneous disease with various patterns of tissue damage. In addition to inflammation and demyelination, widespread axonal and neuronal pathologies are central components of this disease. MS therapies aim to restrain the pathological processes, enhance protective mechanisms, and prevent disease progression. The amino acid copolymer, glatiramer acetate (GA, Copaxone), an approved treatment for MS, has a unique mode of action. Evidence from the animal model experimental autoimmune encephalomyelitis (EAE) and from MS patients indicates that GA affects various levels of the innate and the adaptive immune response, inducing deviation from the pro-inflammatory to the anti-inflammatory pathways. This includes competition for the binding of antigen presenting cells, driving dendritic cells, monocytes, and B-cells towards anti-inflammatory responses, induction of Th2/3 and T-regulatory cells, and downregulating of both Th1 and Th-17 cells. The immune cells induced by GA reach the inflamed disease organ and secrete in situ anti-inflammatory cytokines alleviating the pathological processes. Furthermore, cumulative findings have revealed that in addition to its immunomodulatory activities GA promotes neuroprotective repair processes such as neurotrophic factors secretion and remyelination. This review aims to provide a comprehensive overview on the diverse mechanism of action of GA in EAE/MS, in particular on the in situ effect of GA and its ability to generate neuroprotection and repair in the CNS. In view of its immunomodulatory activity, the beneficial effects of GA in various models of additional autoimmune related pathologies, such as immune rejection and inflammatory bowel disease (IBD), are also presented.

Glatiramer acetate (copaxone) modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation

Background

Glatiramer acetate (GA, Copaxone, Copolymer-1) is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE), an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets.

Methodology/Principal Findings

We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets.

Conclusions

GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.

Oligodendrogenesis and myelinogenesis during postnatal development effect of glatiramer acetate

Myelinogenesis in the mammal nervous system occurs predominantly postnatally. Glatiramer acetate (GA), a drug for the treatment for multiple sclerosis (MS), has been shown to induce immunomodulation and neuroprotection in the inflamed CNS in MS and in experimental autoimmune encephalomyelitis (EAE). Here we investigated whether GA can affect myelinogenesis and oligodendrogenesis in the developing nervous system under nonpathological conditions. Towards this end we studied myelination in mice injected daily by GA, at postnatal Days 7-21. Immunohistological and ultrastructural analyses revealed significant elevation in the number of myelinated axons as well as in the thickness of the myelin encircling them and their resulting g-ratios, in spinal cords of GA-injected mice compared with their PBS-injected littermates, at postnatal Day 14. Elevation in myelinated axons was detected also in the peripheral ventral roots of the motor nerves. GA induced also an increase in axonal diameter, implying an effect on the overall development of the nervous system. A prominent elevation in the amount of progenitor oligodendrocytes and their BrdU incorporation, as well as in mature oligodendrocytes indicated that the effect of GA is linked to increased proliferation and differentiation along the oligodendroglial maturation cascade. In addition, elevation in insulin-like growth factor (IGF-1) and brain-derived neurotrophic factor (BDNF) was found in the white matter of the GA-injected mice. Furthermore, a functional advantage in rotating rod test was exhibited by GA-injected mice over their littermates at postnatal Day 21. These cumulative findings corroborate the beneficial effect of GA on oligodendrogenesis and myelination.

Chronic mild stress eliminates the neuroprotective effect of Copaxone after CNS injury

Copolymer (Cop)-1, also known as glatiramer acetate, is an active compound of Copaxone, a drug widely used by patients with multiple sclerosis (MS). Copaxone functions in MS through two mechanisms of action, namely immunomodulation and neuroprotection. Because the immune system is suppressed or altered in depressed individuals, and since depression is often associated with neurological conditions, we were interested in examining whether the neuroprotective effect of Copaxone persists under conditions of stress-induced depressive behavior. We exposed mice to unpredictable chronic mild stress for 4 weeks and then treated them with three doses of Copaxone at 3-day intervals, with the last dose given immediately before the mice underwent a crush injury to the optic nerve. Whereas nonstressed mice exhibited a strong neuroprotective response after Copaxone treatment, this effect was completely absent in mice that underwent chronic mild stress. Interestingly, when Copaxone was combined with Prozac, the neuroprotective effect of Copaxone was regained, suggesting that chronic mild stress interferes with the neuroprotective effect of Copaxone. These results may shed a light on mechanism of action of Copaxone and lead to new combined therapies for neurodegenerative and neuroinflammatory disorders.

Brain dendritic cells: biology and pathology

Dendritic cells (DC) are the professional antigen-presenting cells of the immune system. In their quiescent and mature form, the presentation of self-antigens by DC leads to tolerance; whereas, antigen presentation by mature DC, after stimulation by pathogen-associated molecular patterns, leads to the onset of antigen-specific immunity. DC have been found in many of the major organs in mammals (e.g. skin, heart, lungs, intestines and spleen); while the brain has long been considered devoid of DC in the absence of neuroinflammation. Consequently, microglia, the resident immune cell of the brain, have been charged with many functional attributes commonly ascribed to DC. Recent evidence has challenged the notion that DC are either absent or minimal players in brain immune surveillance. This review will discuss the recent literature examining DC involvement within both the young and aged steady-state brain. We will also examine DC contributions during various forms of neuroinflammation resulting from neurodegenerative autoimmune disease, injury, and CNS infections. This review also touches upon DC trafficking between the central nervous system and peripheral immune compartments during viral infections, the new molecular technologies that could be employed to enhance our current understanding of brain DC ontogeny, and some potential therapeutic uses of DC within the CNS.

The mechanism of action of glatiramer acetate in multiple sclerosis and beyond

In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), the immune system reacts again self myelin constitutes in the central nervous system (CNS), initiating a detrimental inflammatory cascade that leads to demyelination as well as axonal and neuronal pathology. The amino acid copolymer glatiramer acetate (GA, Copaxone) is an approved first-line treatment for MS that has a unique mode of action. Accumulated evidence from EAE-induced animals and from MS patients indicates that GA affects various levels of the innate and the adaptive immune response, generating deviation from the pro-inflammatory to the anti-inflammatory pathway. This review aims to provide a comprehensive perspective on the diverse mechanism of action of GA in EAE/MS, in particular on the in situ immunomodulatory effect of GA and its ability to generate neuroprotective repair consequences in the CNS. In view of its immunomodulatory activity, the beneficial effect of GA in various models of other autoimmune related pathologies, such as immune rejection and inflammatory bowel disease (IBD) is noteworthy.

Neuroprotective effect of combination therapy of glatiramer acetate and epigallocatechin-3-gallate in neuroinflammation

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system. However, studies of MS and the animal model, experimental autoimmune encephalomyelitis (EAE), indicate that neuronal pathology is the principle cause of clinical disability. Thus, there is need to develop new therapeutic strategies that not only address immunomodulation but also neuroprotection. Here we show that the combination therapy of Glatiramer acetate (GA), an immunomodulatory MS therapeutic, and the neuroprotectant epigallocatechin-3-gallate (EGCG), the main phenol in green tea, have synergistic protective effects in vitro and in the EAE model. EGCG and GA together led to increased protection from glutamate- and TRAIL-induced neuronal cell death in vitro. EGCG combined with GA induced regeneration of hippocampal axons in an outgrowth assay. The combined application of EGCG and GA did not result in unexpected adverse events in vivo. Neuroprotective and neuroregenerative effects could be translated in the in vivo model, where combination treatment with EGCG and GA significantly delayed disease onset, strongly reduced clinical severity, even after onset of symptoms and reduced inflammatory infiltrates. These results illustrate the promise of combining neuroprotective and anti-inflammatory treatments and strengthen the prospects of EGCG as an adjunct therapy for neuroinflammatory and neurodegenerative diseases.

Glatiramer acetate in the treatment of multiple sclerosis: emerging concepts regarding its mechanism of action

Glatiramer acetate is a synthetic, random copolymer widely used as a first-line agent for the treatment of relapsing-remitting multiple sclerosis (MS). While earlier studies primarily attributed its clinical effect to a shift in the cytokine secretion of CD4+ T helper (T(h)) cells, growing evidence in MS and its animal model, experimental autoimmune encephalomyelitis (EAE), suggests that glatiramer acetate treatment is associated with a broader immunomodulatory effect on cells of both the innate and adaptive immune system. To date, glatiramer acetate-mediated modulation of antigen-presenting cells (APC) such as monocytes and dendritic cells, CD4+ T(h) cells, CD8+ T cells, Foxp3+ regulatory T cells and antibody production by plasma cells have been reported; in addition, most recent investigations indicate that glatiramer acetate treatment may also promote regulatory B-cell properties. Experimental evidence suggests that, among these diverse effects, a fostering interplay between anti-inflammatory T-cell populations and regulatory type II APC may be the central axis in glatiramer acetate-mediated immune modulation of CNS autoimmune disease. Besides altering inflammatory processes, glatiramer acetate could exert direct neuroprotective and/or neuroregenerative properties, which could be of relevance for the treatment of MS, but even more so for primarily neurodegenerative disorders, such as Alzheimer's or Parkinson's disease. In this review, we provide a comprehensive and critical overview of established and recent findings aiming to elucidate the complex mechanism of action of glatiramer acetate.

Glatiramer acetate could be a hypothetical therapeutic agent for neuromyelitis optica

Neuromyelitis optica (NMO) is characterized by concurrence of optic neuritis and transverse myelitis, which is typically associated with a spinal cord lesion extending three or more vertebral segments. NMO is an inflammatory, demyelinating central nervous system disorder, and although it has a relapsing course in more than 90% of patients, it differs from multiple sclerosis in that it is more severe, usually spares the brain, and is associated with a longitudinally extensive lesion on spinal cord magnetic resonance imaging (MRI). Furthermore, NMO is associated with a highly specific serum marker called anti-aquaporin-4 antibody, which is believed to have a central pathogenetic role in NMO. Treatment with B-cell specific monoclonal antibody (rituximab) and plasma exchanges appears to reduce the severity and frequency of attacks in NMO, and therefore, B-cell autoimmunity as well as a humoral mechanism may be involved in the pathogenesis of NMO. Glatiramer acetate (GA; also known as Copaxone, COP-1) is a synthetic copolymer of a pool of peptides composed of random sequences of four amino acids: glutamine, lysine, alanine, and tyrosine. GA-specific T-helper 1- (Th1) and 2-type (Th2) cells produce brain-derived neurotrophic factor (BDNF), which may affect neuronal survival and myelin repair. GA treatment also leads to sustained augmentation of BDNF, neurotrophin (NT)-3, and NT-4 expression in various brain regions as demonstrated by histological analysis of immunostained brain sections and BDNF elevation after GA treatment on both protein and mRNA levels. GA-Th2 activation may also have a neuroprotective role in the course of NMO. Furthermore, B cells from GA-treated mice suppress experimental autoimmune encephalomyelitis. The pathogenesis of NMO is largely unknown. However, there is some evidence that B-cell autoimmunity, activation of eosinophils, and B-cell activating factor play important roles, based on neurotrophic factors, neuroprotection, anti-inflammation, and B-cell modulation, GA is thus a hypothetic potential treatment agent for NMO.

Glatiramer acetate attenuates pro-inflammatory T cell responses but does not directly protect neurons from inflammatory cell death

Glatiramer acetate (GA) is a synthetic, random, basic copolymer capable of modulating adaptive T cell responses. In animal models of various inflammatory and degenerative central nervous system disorders, GA-induced T cells cross the blood-brain barrier, secrete high levels of anti-inflammatory cytokines and neurotrophins, and thus both reduce neuronal damage and promote neurogenesis. Recently, it has been suggested that GA itself may permeate the (impaired) blood-brain-barrier and directly protect neurons under conditions of inflammation-mediated neurodegeneration. To test this hypothesis, we examined the direct effects of GA on neuronal functionality and T cell-mediated neuronal apoptosis in culture, acute brain slices, and focal experimental autoimmune encephalomyelitis. GA caused a depolarization of the resting membrane potential and led to an immediate impairment of action potential generation in neurons. Moreover, GA-incubated neurons underwent dose-dependent apoptosis. Apoptosis of ovalbumin peptide-loaded major histocompatibility complex class I-expressing neurons induced by ovalbumin-specific effector T cells could be reduced by pre-incubation of T cells, but not neurons with GA. Similar results could be found using acute brain slices. In focal experimental autoimmune encephalomyelitis, lesion size and neuronal apoptosis could be limited by pretreating rats with GA, whereas intracerebral GA application into the inflammatory lesion had no effect on neuronal survival. Our data suggest that GA attenuates adaptive pro-inflammatory T cell responses, but does not exert direct neuroprotective effects.

Glatiramer acetate (GA, Copolymer-1) an hypothetical treatment option for Rett syndrome

Rett syndrome (RTT) is an X-linked dominant postnatal severe and disabling neurodevelopmental disorder which is the second most common cause for genetic mental retardation in girls and the first pervasive disorder with a known genetic basis. The syndrome is primarily caused by mutations in the Methyl CpG binding protein 2 (MECP2) gene on Xq28. Its protein product MeCP2 acts as a transcriptional repressor or activator depending on the target gene associated. Brain derived neurotrophic factor (BDNF) is a neurotrophic factor playing a major role in neuronal survival, neurogenesis and plasticity. It has been identified as a major MeCP2 target through a candidate gene approach and abnormalities in BDNF homeostasis are believed to contribute to the neurologic phenotype and pato-physiology of part of the symptoms in Mecp2 null mice that show progressive deficits in its expression. Based on the presumed role of BDNF in the pathophysiology of Rett syndrome it is reasonable to assume that interventions that will elevate its levels in the brain of RTT patients will be of therapeutic benefit. Glatiramer acetate (GA, Copolymer 1, Copaxone) an immunomodulator with proven safety and efficacy in Multiple Sclerosis has been reported to cause elevated secretion of BDNF both in animal model and in MS patients. Our hypothesis is that continuous treatment of patients with RTT with Glatiramer acetate might lead to an increase in their brain's BDNF content and an improvement in at least part of the syndrome symptomatology while being safe to use and well tolerated in this population. In a pilot preliminary study we have shown that GA cause elevation of BDNF expression up to the level in naïve control mice in several cortical areas in the Mecp2 mutated mouse brain, but as of yet did not examine the behavioral aspects of this elevation.

The therapeutic equivalence of complex drugs

When the patent of a small molecule drug expires generics may be introduced. They are considered therapeutically equivalent once pharmaceutical equivalence (i.e. identical active substances) and bioequivalence (i.e. comparable pharmacokinetics) have been established in a cross-over volunteer study. However this generic paradigm cannot be applied to complex drugs as biologics and a number of other therapeutic modalities. For copies of biologics the European Medicine Agency and other regulatory agencies have introduced a new regulatory biosimilar pathway which mandates clinical trials to show therapeutic equivalence. However for other complex drugs such as the iron-carbohydrate drugs, low molecular weight heparins (LMWHs), liposomal drugs and the glatiramoids regulatory guidance is still mostly lacking. In this paper we will discuss (therapeutic) experience obtained so far with these different classes of 'complex drugs' and their specifics to provide scientific arguments and criteria for consideration for a regulatory framework for the market authorization for these type of drugs.

Establishment of primary cultures of human brain microvascular endothelial cells to provide an in vitro cellular model of the blood-brain barrier

We describe a method for generating primary cultures of human brain microvascular endothelial cells (HBMVECs). HBMVECs are derived from microvessels isolated from temporal tissue removed during operative treatment of epilepsy. The tissue is mechanically fragmented and size filtered using polyester meshes. The resulting microvessel fragments are placed onto type I collagen-coated flasks to allow HBMVECs to migrate and proliferate. The overall process takes less than 3 h and does not require specialized equipment or enzymatic processes. HBMVECs are typically cultured for approximately 1 month until confluent. Cultures are highly pure ( approximately 97% endothelial cells; approximately 3% pericytes), are reproducible, and show characteristic brain endothelial markers (von Willebrand factor, glucose transporter-1) and robust expression of tight and adherens junction proteins as well as caveolin-1 and efflux protein P-glycoprotein. Monolayers of HBMVECs show characteristically high transendothelial electric resistance and have proven useful in multiple functional studies for in vitro modeling of the human blood-brain barrier.

Looking at the blood-brain barrier: molecular anatomy and possible investigation approaches

The blood-brain barrier (BBB) is a dynamic and complex interface between blood and the central nervous system that strictly controls the exchanges between the blood and brain compartments, therefore playing a key role in brain homeostasis and providing protection against many toxic compounds and pathogens. In this review, the unique properties of brain microvascular endothelial cells and intercellular junctions are examined. The specific interactions between endothelial cells and basement membrane as well as neighboring perivascular pericytes, glial cells and neurons, which altogether constitute the neurovascular unit and play an essential role in both health and function of the central nervous system, are also explored. Some relevant pathways across the endothelium, as well as mechanisms involved in the regulation of BBB permeability, and the emerging role of the BBB as a signaling interface are addressed as well. Furthermore, we summarize some of the experimental approaches that can be used to monitor BBB properties and function in a variety of conditions and have allowed recent advances in BBB knowledge. Elucidation of the molecular anatomy and dynamics of the BBB is an essential step for the development of new strategies directed to maintain or restore BBB integrity and barrier function and ultimately preserve the delicate interstitial brain environment.

Rett syndrome and other autism spectrum disorders--brain diseases of immune malfunction?

Neuroimmunology was once referred to in terms of its pathological connotation only and was generally understood as covering the deleterious involvement of the immune system in various diseases and disorders of the central nervous system (CNS). However, our conception of the function of the immune system in the structure, function, and plasticity of the CNS has undergone a sea change after relevant discoveries over the past two decades, and continues to be challenged by more recent studies of neurodevelopment and cognition. This review summarizes the recent advances in understanding of immune-system participation in the development and functioning of the CNS under physiological conditions. Considering as an example Rett syndrome a devastating neurodevelopmental disease, we offer a hypothesis that might help to explain the part played by immune cells in its etiology, and hence suggests that the immune system might be a feasible therapeutic target for alleviation of some of the symptoms of this and other autism spectrum disorders.

Failure of glatiramer acetate to modify the peripheral T cell repertoire of relapsing-remitting multiple sclerosis patients

Glatiramer acetate (GA) is a random copolymer used as an immunomodulatory treatment in relapsing-remitting multiple sclerosis (RR-MS). Its mechanisms of action are poorly understood, and several hypotheses have been put forward, the majority of which rely on in vitro studies. It has been hypothesised that further to processing by APC, GA could provide a large number of different epitopes with a possible sequence similarity to auto-antigens, which are able to stimulate a large proportion of T cells. Given that in a previous study we showed that the circulating T cells of MS patients present more alterations of the Vbeta T cell receptor (TCR) usage than normal individuals, we explored the possible effect of GA on the ex vivo T cell repertoire of MS patients. Here we used quantitative PCR and electrophoresis to longitudinally analyse (and without any ex vivo stimulation), the CDR3 length distribution (LD) and the amount of Vbeta TCR, as well as various cytokines, in the blood T cells of 10 RR-MS patients before and after 3 months and 2 years of GA treatment. In addition, we also determined the status of responder and non-responder patients after 24 months of GA treatment based on clinical and radiological criteria. We found no significant modification of cytokine production, Vbeta TCR mRNA accumulation or CDR3-LD in the patients after short-term and long-term treatment. In addition, we did not observe any difference in CDR3-LD in the GA responder patients (n=6) compared to non-responder patients (n=4). Focusing our study on responder patients, we performed TCR repertoire analysis in the CD4+ and CD8+ compartment. Alterations of CDR3-LD were predominantly found in the CD8+ compartment, without any significant influence of GA treatment. Finally, the T cell repertoire variations in MS patients treated with GA and healthy controls were equivalent. Collectively, our data suggest that GA therapy does not induce significant variations in cytokine production or TCR usage in MS patients.

A coat of many colors: neuroimmune crosstalk in human immunodeficiency virus infection

The use of antiretroviral therapy has reduced mortality and increased the quality of life of HIV-1-infected people, particularly in more developed countries where access to treatment is more widespread. However, morbidities continue, which include HIV-1-associated neurocognitive disorders (HAND). Subtle cognitive abnormalities and low-level viral replication underlie disease. The balance between robust antiviral adaptive immunity, neuronal homeostatic mechanisms, and neuroprotective factors on one hand and toxicities afforded by dysregulated immune activities on the other govern disease. New insights into the pathobiological processes for neuroimmune-linked disease and ways to modulate such activities for therapeutic gain are discussed. Better understanding of the complexities of immune regulation during HAND can improve diagnosis and disease outcomes but is also relevant for the pathogenesis of a broad range of neurodegenerative disorders.

Application of glatiramer acetate to neurodegenerative diseases beyond multiple sclerosis: the need for disease-specific approaches

Adaptive and innate immunity, if well controlled, contribute to the maintenance of the CNS, as well as to downregulation of adverse acute and chronic neurological conditions. T cells that recognize CNS antigens are needed to activate resident immune cells and to recruit blood-borne monocytes, which act to restore homeostasis and facilitate repair. However, boosting such a T-cell response in a risk-free way requires a careful choice of the antigen, carrier, and regimen. A single vaccination with CNS-derived peptides or their weak agonists reduces neuronal loss in animal models of acute neurodegeneration. Repeated injections are needed to maintain a long-lasting effect in chronic neurodegenerative conditions, yet the frequency of the injections seems to have a critical effect on the outcome. An example is glatiramer acetate, a compound that is administered in a daily regimen to patients with multiple sclerosis. A single injection of glatiramer acetate, with or without an adjuvant, is neuroprotective in some animal models of acute CNS injuries. However, in an animal model of amyotrophic lateral sclerosis, a single injection of adjuvant-free glatiramer acetate is insufficient, while daily injections are not only ineffective but can carry an increased risk of mortality in female mice.Thus, considering immune-based therapies as a single therapy, rather than as a family of therapies that are regimen dependent, may be misleading. Moreover, the vaccination regimen and administration of a compound, even one shown to be safe in humans for the treatment of a particular neurodegenerative disease, must be studied in preclinical experiments before it is tested in a clinical trial for a novel indication; otherwise, an effective drug in a certain regimen for one disease may be ineffective or even carry risks when used for another disorder.

Protective autoimmunity in the nervous system

The immune system can play both detrimental and beneficial roles in the nervous system. Multiple arms of the immune system, including T cells, B cells, NK cells, mast cells, macrophages, dendritic cells, microglia, antibodies, complement and cytokines participate in limiting damage to the nervous system during toxic, ischemic, hemorrhagic, infective, degenerative, metabolic and immune-mediated insults and also assist in the process of repair after injury has occurred. Immune cells have been shown to produce neurotrophic growth factors and interact with neurons and glial cells to preserve them from injury and stimulate growth and repair. The immune system also appears to participate in proliferation of neural progenitor stem cells and their migration to sites of injury. Neural stem cells can also modify the immune response in the central and peripheral nervous system to enhance neuroprotective effects. Evidence for protective and reparative functions of the immune system has been found in diverse neurologic diseases including traumatic injury, ischemic and hemorrhagic stroke, multiple sclerosis, infection, and neurodegenerative diseases (Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis). Existing therapies including glatiramer acetate, interferon-beta and immunoglobulin have been shown to augment the protective and regenerative aspects of the immune system in humans, and other experimental interventions such as vaccination, minocycline, antibodies and neural stem cells, have shown promise in animal models of disease. The beneficent aspects of the immune response in the nervous system are beginning to be appreciated and their potential as pharmacologic targets in neurologic disease is being explored.

Adaptive immune neuroprotection in G93A-SOD1 amyotrophic lateral sclerosis mice

Background

Innate neuroimmune dysfunction is a pathobiological feature of amyotrophic lateral sclerosis (ALS). However, links, if any, between disease and adaptive immunity are poorly understood. Thus, the role of T cell immunity in disease was investigated in human G93A superoxide dismutase 1 (SOD1) transgenic (Tg) mice and subsequently in ALS patients.

Methods and Findings

Quantitative and qualitative immune deficits in lymphoid cell and T cell function were seen in G93A-SOD1 Tg mice. Spleens of Tg animals showed reductions in size, weight, lymphocyte numbers, and morphological deficits at terminal stages of disease compared to their wild-type (Wt) littermates. Spleen sizes and weights of pre-symptomatic Tg mice were unchanged, but deficits were readily seen in T cell proliferation coincident with increased annexin-V associated apoptosis and necrosis of lymphocytes. These lymphoid deficits paralleled failure of Copolymer-1 (COP-1) immunization to affect longevity. In addition, among CD4⁺ T cells in ALS patients, levels of CD45RA⁺ (naïve) T cells were diminished, while CD45RO⁺ (memory) T cells were increased compared to age-matched caregivers. In attempts to correct mutant SOD1 associated immune deficits, we reconstituted SOD1 Tg mice with unfractionated naïve lymphocytes or anti-CD3 activated CD4⁺CD25⁺ T regulatory cells (Treg) or CD4⁺CD25⁻ T effector cells (Teff) from Wt donor mice. While naive lymphocytes failed to enhance survival, both polyclonal-activated Treg and Teff subsets delayed loss of motor function and extended survival; however, only Treg delayed neurological symptom onset, whereas Teff increased latency between disease onset and entry into late stage.

Conclusions

A profound and progressive immunodeficiency is operative in G93A-SOD1 mice and is linked to T cell dysfunction and the failure to elicit COP-1 neuroprotective immune responses. In preliminary studies T cell deficits were also observed in human ALS. These findings, taken together, suggest caution in ascribing vaccination outcomes when these animal models of human ALS are used for study. Nonetheless, the abilities to improve neurological function and life expectancy in G93A-SOD1 Tg mice by reconstitution with activated T cells do provide opportunities for therapeutic intervention.

Can the immune system be harnessed to repair the CNS?

Experimental and clinical data have demonstrated that activating the immune system in the CNS can be destructive. However, other studies have shown that enhancing an immune response can be therapeutic, and several clinical trials have been initiated with the aim of boosting immune responses in the CNS of individuals with spinal cord injury, multiple sclerosis and Alzheimer's disease. Here, we evaluate the controversies in the field and discuss the remaining scientific challenges that are associated with enhancing immune function in the CNS to treat neurological diseases.

Central nervous system effects of current and emerging multiple sclerosis-directed immuno-therapies

OBJECTIVE

To review the direct and indirect effects on the central nervous system (CNS) of systemically administered immuno-modulatory therapies in use or under evaluation for the relapsing forms of multiple sclerosis (MS).

METHODS

We summarize data published by our own lab and by others that delineate the effects of such therapies on in vitro neural cell cultures and in animal model-based systems.

RESULTS

The long-approved therapies, interferon beta (IFNbeta) and glatiramer acetate (GA), do not readily access the CNS. These agents can still indirectly have an effect on disease-related immune regulatory and effector functions within the CNS by modulating the properties of systemic immune cells that migrate to this compartment. Such immune cells could interact with perivascular and innate immune cells that are involved in immune regulation and with cells that are either targets of the disease process (oligodendrocytes, neurons) and/or are involved with repair (progenitor cells). Newer agents reported to favorably impact on relapse frequency in MS include the sphingosine-1-phosphate agonist, fingolimod, and the lipophilic statin, simvastatin. Both agents access the CNS and thus represent examples of agents that could directly impact on disease-relevant injury and repair process within the CNS.

CONCLUSIONS

The observations reviewed in this report regarding indirect and direct effects of immuno-modulatory agents on the CNS indicate the need to understand and monitor the neurobiologic effects of such therapies.

Amino acid copolymer-specific IL-10-secreting regulatory T cells that ameliorate autoimmune diseases in mice

IL-10-secreting regulatory T cell lines specific to glatiramer acetate [poly(Y,E,A,K)n] or poly(Y,F,A,K)n have been established from the enlarged spleen and lymph nodes that result from copolymer treatment of SJL mice in which experimental autoimmune encephalomyelitis was induced by PLP139-151. These CD4+CD25+T cell lines secrete high levels of IL-10 and IL-13 but only small amounts of IL-4 and virtually no TGF-beta, IL-17, IL-6, IFN-gamma, or TNF-alpha. Their phenotypes are particularly characterized by the absence of Foxp3 and the presence of two TNFR family members, CD30 and GITR. The lines proliferated specifically to the immunizing copolymers but were autoantigen-nonspecific, in that the same T cell line could suppress autoimmunity induced by three different autoantigens in SJL mice, i.e., PLP139-151(EAE), MBP85-99 (EAE), and bovine peripheral nerve myelin (experimental autoimmune neuritis), indicating they function by bystander suppression.