Laquinimod,a once-daily oral drug in development for the treatment of relapsing–remitting multiple sclerosis

Laquinimod is a novel, small, orally administered medication that has demonstrated efficacy in the treatment of multiple sclerosis, a chronic inflammatory demyelinating disease of the CNS. In preclinical testing, laquinimod inhibited the development of both acute and chronic paralysis in the multiple sclerosis model, experimental autoimmune encephalomyelitis. Furthermore, laquinimod reduced inflammation, demyelination and axonal damage in experimental autoimmune encephalomyelitis in mice treated at disease induction or at clinical disease onset. Recent findings from the clinical trials indicate that laquinimod has significant effects in reducing relapse rate and has more pronounced effects in reducing sustained disability progression as well as brain atrophy, with a good safety profile. In conclusion, preclinical studies show that laquinimod’s unique mechanisms of action, including its immunomodulatory and CNS-protective effects, translate into clinical benefits in relapsing–remitting multiple sclerosis patients.     

Laquinimod in the treatment of relapsing remitting multiple sclerosis

Introduction: Laquinimod is a new once-daily oral administrable agent, which is under investigation in a phase 3 clinical trial for relapsing remitting multiple sclerosis (RRMS) and in a phase 2 clinical trial for primary progressive MS (PPMS).

Areas covered: The pharmacokinetic, pharmacodynamic and the safety profiles of laquinimod are covered in this review. In preclinical studies, the ability to prevent both experimental autoimmune encephalomyelitis and experimental autoimmune neuritis has been demonstrated. Reduced cell infiltration, demyelination, axonal damage and a shift of T-helper cell responses have been shown. Accordingly, in human studies, a decrease of pro-inflammatory and an increase of anti-inflammatory cytokines have been measured and a significant reduction of disease progression and a decrease in brain volume loss has been demonstrated. During all clinical studies a favorable safety profile was observed for 0.6mg laquinimod. New information about cardiovascular events is prompting the discontinuation of higher dosing regimens in both ongoing trials.

Expert opinion: Laquinimod is a first in class oral agent with high potential to reduce disease progression in RRMS and PPMS. Owing to its favorable safety profile, a combination with 0.6mg laquinimod and other disease modifying therapies could be an option in future MS therapy.     

Phenotype of Antigen Unexperienced T<Subscript>H</Subscript> Cells in the Inflamed Central Nervous System in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis is a chronic, disseminated inflammation of the central nervous system which is thought to be driven by autoimmune T cells. Genetic association studies in multiple sclerosis and a large number of studies in the animal model of the disease support a role for effector/memory T helper cells. However, the mechanisms underlying relapses, remission and chronic progression in multiple sclerosis or the animal model experimental autoimmune encephalomyelitis, are not clear. In particular, there is only scarce information on the role of central nervous system-invading naive T helper cells in these processes. By applying two-photon laser scanning microscopy we could show in vivo that antigen unexperienced T helper cells migrated into the deep parenchyma of the inflamed central nervous system in experimental autoimmune encephalomyelitis, independent of their antigen specificity. Using flow cytometric analyses of central nervous system-derived lymphocytes we found that only antigen-specific, formerly naive T helper cells became activated during inflammation of the central nervous system encountering their corresponding antigen.     

Synthesis and biological evaluation of new 1,2-dihydro-4-hydroxy-2-oxo-3-quinolinecarboxamides for treatment of autoimmune disorders: structure-activity relationship

Roquinimex-related 3-quinolinecarboxamide derivatives were prepared and evaluated for treatment of autoimmune disorders. The compounds were tested in mice for their inhibitory effects on disease development in the acute experimental autoimmune encephalomyelitis model and selected compounds in the beagle dog for induction of proinflammatory reaction. Structure-activity relationships are discussed. Compound 8c, laquinimod, showed improved potency and superior toxicological profile compared to the lead compound roquinimex (1b, Linomide) and was selected for clinical studies (currently in phase II).     

Minocycline up-regulates the expression of brain-derived neurotrophic factor and nerve growth factor in experimental autoimmune encephalomyelitis

Previous evidence demonstrated that minocycline could ameliorate clinical severity of experimental autoimmune encephalomyelitis and exhibit several anti-inflammatory and neuroprotective activities. However, few studies have been carried out to assess its effects on the expression of neurotrophins in experimental autoimmune encephalomyelitis or multiple sclerosis. Here we investigated the alteration of brain-derived neurotrophic factor and nerve growth factor in the sera, cerebral cortex, and lumbar spinal cord of experimental autoimmune encephalomyelitis C57 BL/6 mice in vivo as well as the splenocytes culture supernatants in vitro after minocycline administration. Our results demonstrated that minocycline could up-regulate the expression of brain-derived neurotrophic factor and nerve growth factor both in peripheral (sera and splenocytes culture supernatants) and target organs (cerebral cortex and lumber spinal cord) of mice with experimental autoimmune encephalomyelitis. These data suggest that up-regulation of neurotrophins in experimental autoimmune encephalomyelitis may be a novel neuroprotective mechanism of minocycline.     

Oral laquinimod therapy in relapsing multiple sclerosis

Background: Multiple sclerosis (MS) is a chronic autoimmune disease of the CNS. Early treatment reduces the number of relapses, limits progression of disability, and improves quality of life; however, existing therapies are only partially effective and require parenteral administration. Objective: To review current experience with laquinimod as a novel immunomodulatory therapy for MS. Results: Laquinimod is a new quinolonecarboxamide that has demonstrated efficacy in animal models of several autoimmune diseases, including MS. It shows immunomodulatory effects, likely through Th1/Th2 shift, but does not lead to immunosuppression. Laquinimod is metabolized in the liver, primarily by the CYP3A4 enzyme. Phase II studies in relapsing MS demonstrate a dose-response effect on disease activity, measured by number of active lesions on brain magnetic resonance imaging, and show favorable tolerability and safety based on clinical and laboratory indicators. Two Phase III studies currently in progress are evaluating the efficacy of laquinimod 0.6 mg/day in relapsing MS. The drug was granted a fast track review by the FDA in 2009. Conclusion: Laquinimod is a novel, orally administered immunomodulator that has advanced to the pre-submission stage and may become an alternative to the current injectable first-line treatments for relapsing MS.     

Animal models in neurology: drawbacks and opportunities

Animal models have been used widely in neurology since many decades. They have led to an improved understanding of the pathophysiological processes underlying frequent diseases as multiple sclerosis or Parkinson's disease and enabled the development of highly effective therapeutical approaches. Current developments, drawbacks and limitations of animal models in neurology are discussed with a special focus on the experimental autoimmune encephalomyelitis - model of multiple sclerosis.     

Laquinimod (ABR-215062) for the treatment of relapsing multiple sclerosis

Laquinimod (ABR-215062) is an oral immunomodulatory agent developed for the treatment of relapsing multiple sclerosis (MS). Laquinimod is a derivative of the drug roquinimex, but lacks the unacceptable side effect profile of this drug which was documented in previous MS trials. Preclinical studies in experimental models of MS, both of autoimmune neuroinflammation and of toxin induced demyelination show a multitude of immunomodulatory and anti-inflammatory effects, including some that are effective directly in the central nervous system. Phase I study results confirmed the safety and tolerability of laquinimod, and phase II and III studies provide a picture of a consistent albeit moderate effect on relapse rate and new lesion development on magnetic resonance imaging combined with a stronger effect on sustained progression and brain atrophy. These findings make laquinimod a potentially useful future treatment of MS.     

Repulsive Guidance Molecule-a and Demyelination: Implications for Multiple Sclerosis

Drug development for neurodegenerative and neuroinflammatory diseases such as multiple sclerosis and traumatic brain injury is challenging. One promising strategy is to target a molecule with multiple biological actions affecting divergent pathophysiological disease phases simultaneously since these diseases arise from multiple pathological phases. In recent years, we pursued this strategy with a focus on multiple sclerosis and spinal cord injury and found that repulsive guidance molecule-a (RGMa) inhibits regeneration of injured CNS axons following spinal cord injury. We also found that RGMa enhances CD4(+) T cell activation facilitating CNS demyelination in an animal model of MS, mouse experimental autoimmune encephalomyelitis (EAE), which supports the idea that RGMa has distinct pathological actions. The multiple functions of RGMa in the CNS and the immune system would provide a therapeutic opportunity to concurrently block the autoimmune reactions and axon injury in neurodegenerative and neuroinflammatory diseases. In this article, we introduce the therapeutic potential of targeting RGMa as a novel intervention for MS and spinal cord injury.     

Epicutaneous immunization with myelin basic protein protects from the experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) with limited treatment modalities. One of the experimental methods that protect from autoimmune diseases is oral tolerance. However, this method failed to show therapeutic efficacy in clinical trials. In our previous work, we found that epicutaneous (ec) immunization with a protein antigen induces a state of profound immunosuppression that inhibits inflammatory response in contact sensitivity (CS), experimental autoimmune encephalomyelitis (EAE) in B10.PL mice that develop chronic form of disease, and also delayed allogeneic skin graft rejection. In the current work, we showed that ec immunization with MBP protects from relapsing and remitting EAE. Protection from the disease correlated with decreased number of mononuclear cells isolated from CNS. Additionally, histological examination showed only a slight mononuclear cell infiltration in spinal cords of mice ec immunized with MBP when compared to positive control where animals were ec treated with PBS before disease induction.     

Peroxisome proliferator-activated receptor agonists as potential therapeutic agents in multiple sclerosis

Peroxisome proliferator-activated receptors (PPARs) have been extensively studied for gene regulation in glucose and lipid metabolism. It has been recently implicated that PPARs regulate cellular proliferation and inflammatory responses; some agonists for PPARs ameliorate experimental autoimmune encephalomyelitis, a model of multiple sclerosis (MS) in humans. This article will outline current experimental evidence suggesting potential clinical benefits for patients with MS.     

Anthraquinone derivative O,O'-bis-(3'-iodopropyl)-1,4-dihidroxyanthraquinone modulates immune response and improves experimental autoimmune encephalomyelitis

The present study investigated the effects of the anthraquinone derivative (O,O'-bis-(3'-iodopropyl)-1,4-dihidroxyanthraquinone - DIPDHAQ), mitoxantrone analog, in an experimental autoimmune encephalomyelitis (EAE) model. The results showed that DIPDHAQ treatment improved the clinical signs of the disease (n=10; vehicle: 3.8±0.3; DIPDHAQ: 1.4±0.9). The improvement was associated with a decrease of inflammatory cells, demyelination, IL-17, IFN-γ, IL-12p40, IL-6, TGF-β, CCL5 and CCL20 levels in the spinal cord. DIPDHAQ presented a low cytotoxicity when in vitro assays were performed. Therefore, the findings suggest a major role for DIPDHAQ in multiple sclerosis, disease characterized as an autoimmune inflammatory disorder against myelin proteins of the brain and spinal cord. The attenuation of inflammation and consequently improvement of clinical signs, involving a decrease of pro-inflammatory cytokines and the low cytotoxicity of DIPDHAQ, suggest that this compound could be used as an alternative treatment for autoimmune diseases in the central nervous system.     

Anti-inflammatory effects of levetiracetam in experimental autoimmune encephalomyelitis

Levetiracetam (LEV) is an established anticonvulsant with numerous mechanisms of action. Apart from its anti-epileptic effects, recent experimental studies suggest anti-inflammatory properties via modulation of interleukin (IL)-1β and transforming-growth-factor (TGF)-β1. However, its anti-inflammatory properties have not yet been examined in an autoimmune inflammatory disease of the central nervous system (CNS). We investigated LEV anti-inflammatory properties in experimental autoimmune encephalomyelitis, an established mouse model of multiple sclerosis. FACS analyses, ELISA, histology and rt-PCR experiments were done to explore potential anti-inflammatory effects. In line with prior studies, we demonstrate that LEV modulates both the relative gene expression and secretion of IL-1β and TGF-1β. However, these changes were not sufficient to alter the disease course or histological parameters. Additionally, LEV showed no effects on the absolute number of different immune cell subsets. In summary, LEV showed only minor anti-inflammatory effects not sufficient to ameliorate disease course in an autoimmune inflammatory disease of CNS.     

Oral flavonoids delay recovery from experimental autoimmune encephalomyelitis in SJL mice

Flavonoids are food components that appear to have potential beneficial health effects. There is a range of in vitro studies supporting the anti-oxidant and anti-inflammatory properties of flavonoids. Previously, we demonstrated that in vitro flavonoids, including luteolin and apigenin, inhibit proliferation and IFN-gamma production by murine and human autoimmune T cells. In the present study, we examined the effects of oral flavonoids as well as of curcumin on autoimmune T cell reactivity in mice and on the course of experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. Continuous oral administration of flavonoids significantly affected antigen-specific proliferation and IFN-gamma production by lymph node-derived T cells following immunization with an EAE-inducing peptide. Both luteolin and apigenin suppress proliferative responses as they did in vitro, whereas IFN-gamma production on the other hand was enhanced. Other flavonoids exerted differential effects on proliferation and IFN-gamma production. The effects of flavonoids and curcumin on EAE were assessed using either passive transfer of autoimmune T cells or active disease induction. In passive EAE, flavonoids led to delayed recovery of clinical symptoms rather than to any reduction in disease. In active EAE, the effects were less pronounced but also, in this case, the flavonoid hesperitin delayed recovery. Oral curcumin had overall mild but beneficial effects. Our results indicate that oral flavonoids fail to beneficially influence the course of EAE in mice but, instead, suppress recovery from acute inflammatory damage.     

Therapeutic strategies in autoimmune diseases by interfering with leukocyte endothelium interaction

The interaction of leukocytes with the vessel endothelium to facilitate the extravasation into the tissue represents a key process of the body's defense mechanisms. Excessive recruitment of leukocytes into the inflamed tissue in chronic diseases like autoimmune disorders could be prevented by interfering with the mechanisms of leukocyte extravasation. Significant progress in elucidating the molecular basis of the trafficking of leukocytes from the blood stream to the extravascular tissue has been achieved that enables new strategies for therapeutic approaches. The multistep process of leukocyte rolling, firm adhesion and transmigration through the endothelial wall is facilitated by a dynamic interplay of adhesion receptors on both leukocytes and endothelial cells as well as chemokines. In preclinical studies using various animal models, promising results have been received demonstrating that blocking of adhesion receptors of the selectin and integrin families improved the inflammation process in models of ulcerative colitis, autoimmune encephalomyelitis or contact hypersensitivity. In addition to the targeting of adhesion receptors by antibodies, small molecules that mimic epitopes of adhesion receptor ligands have been developed and successfully applied in animal models. Clinical studies revealed a limited response using antibodies to selectins or LFA-1 integrins compared with animal models. However, using humanized antibodies to the alpha4- integrin subunit significant efficacy has been demonstrated in autoimmune diseases like psoriasis, multiple sclerosis and inflammatory bowel disease.     

Potassium channel blockade by the sea anemone toxin ShK for the treatment of multiple sclerosis and other autoimmune diseases

Expression of the two lymphocyte potassium channels, the voltage-gated channel Kv1.3 and the calcium activated channel IKCa1, changes during differentiation of human T cells. While IKCa1 is the functionally dominant channel in naive and "early" memory T cells, Kv1.3 is crucial for the activation of terminally differentiated effector memory (TEM) T cells. Because of the involvement of TEM cells in autoimmune processes, Kv1.3 is regarded as a promising target for the treatment of T-cell mediated autoimmune diseases such as multiple sclerosis and the prevention of chronic transplant rejection. ShK, a 35-residue polypeptide toxin from the sea anemone, Stichodactyla helianthus, blocks Kv1.3 at low picomolar concentrations. ShK adopts a central helix-kink-helix fold, and alanine-scanning and other mutagenesis studies have defined its channel-binding surface. Models have been developed of how this toxin effects K+-channel blockade and how its docking configuration might differ in ShK-Dap22, which contains a single side chain substitution that confers specificity for Kv1.3 blockade. ShK, ShK-Dap22 and the Kv1.3 blocking scorpion toxin kaliotoxin have been shown to prevent and treat experimental autoimmune encephalomyelitis in rats, a model for multiple sclerosis. A fluoresceinated analog of ShK, ShK-F6CA, has been developed, which allows the detection of activated TEM cells in human and animal blood samples by flow cytometry and the visualization of Kv1.3 channel distribution in living cells. ShK and its analogs are currently undergoing further evaluation as leads in the development of new biopharmaceuticals for the treatment of multiple sclerosis and other T-cell mediated autoimmune disorders.     

S-nitrosoglutathione a Physiologic Nitric Oxide Carrier Attenuates Experimental Autoimmune Encephalomyelitis

S-nitrosoglutathione (GSNO) is a physiological nitric oxide molecule which regulates biological activities of target proteins via s-nitrosylation leading to attenuation of chronic inflammation. In this study we evaluated the therapeutic efficacy of GSNO in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Oral administration of GSNO (0.5 or 1.0 mg/kg) reduced disease progression in chronic models (SJL and C57BL/6) of EAE induced with PLP_(139–151) or MOG_(35–55) peptides, respectively. GSNO attenuated EAE disease by reducing the production of IL17 (from Th_i or Th17 cells) and the infiltration of CD4 T cells into the central nervous system without affecting the levels of Th1 (IFNγ) and Th2 (IL4) immune responses. Inhibition of IL17 was observed in T cells under normal as well as Th17 skewed conditions. In vitro studies showed that the phosphorylation of STAT3 and expression of RORγ, key regulators of IL17 signaling, were reduced while phosphorylation of STAT4 or STAT6 and expression of T-bet or GATA3 remained unaffected, suggesting that GSNO preferentially targets Th17 cells. Collectively, GSNO attenuated EAE via modulation of Th17 cells and its effects are independent of Th1 or Th2 cells functions, indicating that it may have therapeutic potential for Th17-mediated autoimmune diseases.     

Towards cannabis and cannabinoid treatment of multiple sclerosis

Multiple sclerosis is a common human demyelinating disease of the central nervous system (CNS), and it is thought to involve autoimmune responses to CNS myelin antigens. Current symptomatic therapies for multiple sclerosis are in some cases ineffective and may have a high risk of serious side effects. This has led some multiple sclerosis patients to self-medicate with cannabis, which anecdotal evidence suggests may be beneficial in controlling symptoms such as spasticity, pain, tremor and bladder dysfunction. In support of these claims, results from experimental studies have suggested that cannabinoid-based treatments may be beneficial in a wide number of diseases. Furthermore, recent research in animal models of multiple sclerosis has demonstrated the efficacy of cannabinoids in controlling disease-induced symptoms such as spasticity and tremor, as well as in ameliorating the severity of clinical disease. However, these initially promising results have not yet been fully translated into the clinic. Although cannabinoid treatment of multiple sclerosis symptoms has been shown to be both well tolerated and effective in a number of subjective tests in several small-scale clinical trials, objective measures demonstrating the efficacy of cannabinoids are still lacking. Currently, a number of large-scale phase III clinical trials are under way to further elucidate the use of cannabinoids in the symptomatic treatment of multiple sclerosis. This review highlights the recent advances in our understanding of the endocannabinoid system, discusses both the experimental and clinical evidence for the use of cannabinoids to treat multiple sclerosis and explores possible future strategies of cannabinoid therapy in multiple sclerosis.     

Anti-inflammatory properties of cholinergic up-regulation: A new role for acetylcholinesterase inhibitors

We investigated the anti-inflammatory effects of acetylcholinesterase inhibitors (AChEI) at the cellular and molecular levels. AChEI suppressed lymphocyte proliferation and pro-inflammatory cytokine production, as well as extracellular esterase activity. Anti-inflammatory activity was mediated by the alpha7 nicotinic acetylcholine receptor (neuronal); the muscarinic receptor had the opposite effect. Treatment of the central nervous system (CNS) inflammatory disease, experimental autoimmune encephalomyelitis (EAE), with EN101, an anti-sense oligodeoxynucleotide, targeted to AChE mRNA, reduced the clinical severity of the disease and CNS inflammation intensity. The results of our experiments suggest that AChEI increase the concentration of extracellular acetylcholine (ACh), rendering it available for interaction with a nicotinic receptor expressed on lymphocytes. Our findings point to a novel role for AChEI which may be relevant in CNS inflammatory diseases such as EAE and multiple sclerosis. They also emphasize the importance of cholinergic balance in neurological disorders, such as Alzheimer's disease and myasthenia gravis, in which these drugs are used.