Mode of action and clinical studies with fumarates in multiple sclerosis

Mechanism of action and therapeutic potential of dimethyl fumarate in ischemic stroke

Dimethyl fumarate (DMF) is an immunomodulatory drug currently approved for the treatment of multiple sclerosis and psoriasis. Its benefits on ischemic stroke outcomes have recently come to attention. To date, only tissue plasminogen activators (tPAs) and clot retrieval methods have been approved by the FDA for the treatment of ischemic stroke. Ischemic conditions lead to inflammation through diverse mechanisms, and recanalization can worsen the state. DMF and the nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway it regulates seem to be important in postischemic inflammation, and animal studies have demonstrated that the drug improves overall stroke outcomes. Although the exact mechanism is still unknown, studies indicate that these beneficial impacts are due to the modulation of immune responses, blood-brain barrier permeability, and hemodynamic adjustments. One major component evaluated before, during, and after tPA therapy in stroke patients is blood pressure (BP). Recent studies have found that DMF may impact BP. Both hypotension and hypertension need correction before treatment, which may delay the appropriate intervention. Since BP management is crucial in managing stroke patients, it is important to consider DMF's role in this matter. That being said, it seems further investigations on DMF may lead to an alternative approach for stroke patients. In this article, we discuss the mechanistic roles of DMF and its potential role in stroke based on previously published literature and laboratory findings.

Response to fumaric acid esters for plaque type psoriasis in real-world practice is largely independent of patient characteristics at baseline - a multivariable regression analysis from the German psoriasis registry PsoBest

OBJECTIVES

Fumaric acid esters (FAEs) are a well-established treatment option for long-term therapy of moderate to severe plaque psoriasis. This study examines effectiveness of FAEs for the treatment of plaque psoriasis in real-world practice at 12 months and if patient characteristics affect the odds of clinical response.

METHODS

A descriptive, multivariable logistic regression analysis was conducted in a cohort drawn from the German registry PsoBest. Baseline patient characteristics were assessed as potential treatment effect modifiers.

RESULTS

444 patients (mean age 47.0 years, 39.0% female) were eligible for response analysis using nonresponder imputation at month 12. Of these, 39.6% achieved clinical response, i.e., Psoriasis Area and Severity Index (PASI) ≤3 or skin clearance. In logistic regression analysis (R² = 0.114), only baseline PASI was a significant factor: patients with PASI <10 had a 4 times higher odds (p ≤ 0.001, OR 4.088), patients with PASI of 10-20 a twofold higher odds of response (p ≤ 0.044, OR 1.961) compared to those with PASI >20. Neither sex, age, body weight, disease duration, comorbidity nor pre-treatment had an impact on the odds of response (p > 0.05).

CONCLUSIONS

FAEs showed a favorable response at 12 months, largely independent of patient characteristics.

Anti-Inflammatory and Anti-Oxidant Effect of Dimethyl Fumarate in Cystic Fibrosis Bronchial Epithelial Cells

Cystic Fibrosis (CF) is caused by mutations on the CF transmembrane conductance regulator (CFTR) gene and is associated with chronic infection and inflammation. Recently, it has been demonstrated that LPS-induced CFTR dysfunction in airway epithelial cells is due to an early oxidative stress. Dimethyl fumarate (DMF) is an approved anti-inflammatory and anti-oxidant drug for auto-immune and inflammatory diseases, but its role in the CF has never been investigated. In this study, we examined the effect of DMF on CF-related cytokines expression, ROS measurements and CFTR channel function. We found that DMF reduced the inflammatory response to LPS stimulation in both CF and non-CF bronchial epithelial cells, both as co-treatment and therapy, and restored LPS-mediated decrease of Trikafta™-mediated CFTR function in CF cells bearing the most common mutation, c.1521_1523delCTT (F508del). DMF also inhibited the inflammatory response induced by IL-1β/H₂O₂ and IL-1β/TNFα, mimicking the inflammatory status of CF patients. Finally, we also demonstrated that DMF exhibited an anti-oxidant effect on CF cells after different inflammatory stimulations. Since DMF is an approved drug, it could be further investigated as a novel anti-inflammatory molecule to ameliorate lung inflammation in CF and improve the CFTR modulators efficacy.

The Nrf2 Pathway in Ischemic Stroke: A Review

Ischemic stroke, characterized by the sudden loss of blood flow in specific area(s) of the brain, is the leading cause of permanent disability and is among the leading causes of death worldwide. The only approved pharmacological treatment for acute ischemic stroke (intravenous thrombolysis with recombinant tissue plasminogen activator) has significant clinical limitations and does not consider the complex set of events taking place after the onset of ischemic stroke (ischemic cascade), which is characterized by significant pro-oxidative events. The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of a great number of antioxidant and/or defense proteins, has been pointed as a potential pharmacological target involved in the mitigation of deleterious oxidative events taking place at the ischemic cascade. This review summarizes studies concerning the protective role of Nrf2 in experimental models of ischemic stroke, emphasizing molecular events resulting from ischemic stroke that are, in parallel, modulated by Nrf2. Considering the acute nature of ischemic stroke, we discuss the challenges in using a putative pharmacological strategy (Nrf2 activator) that relies upon transcription, translation and metabolically active cells in treating ischemic stroke patients.

Dimethyl fumarate protects the aged brain following chronic cerebral hypoperfusion-related ischemia in rats in Nrf2-dependent manner

It has been stated that chronic cerebral hypoperfusion (CCH) markedly prompts neuronal damage and affects cognition. Dimethyl fumarate (DMF), a nuclear erythroid 2-related factor 2 (Nrf2) activator, represents a class of molecules exhibiting neuroprotection. We explored the effect of DMF on CCH using a model of permanent left common carotid occlusion. The left common carotid artery was occluded and then DMF (100mg.kg^-1) was orally administrated three times per week for four consecutive weeks. Behavioral rests, PET imaging and Hematoxylin and Eosin staining, were examined and also, the hippocampal level of inflammatory, Nrf2 antioxidant, neuronal plasticity and apoptotic factors were determined using Western blot analysis and related ELISA kits. The neurological deficit scores were significantly reduced in the treatment group compared with the CCH group (P<0.001). DMF decreased the novel object recognition index (NOR) compared with the CCH group, while CCH + DMF increased the NOR compared with the CCH group (P<0.001). CCH + DMF reduces the ratio of Bax/Bcl2 and capase-3 activity in comparison to the CCH group (P<0.001). Treatment with DMF increased Nrf2, NAD(P)H dehydrogenase-1 and Heme oxygenase-1 and decreased Tumor necrosis factor α and Nuclear factor-κB density compared with the CCH group (P<0.001). A significant increase in brain-derived neurotrophic factor and c-fos was found in DMF-treated rats compared with the CCH group (P<0.001). Also, retinoic acid inhibits Nrf2 activation via DMF and increases inflammatory factors in hypoperfused rats' hippocampus compared with the CCH group (P<0.001). Long-term DMF treatment induces the Nrf2 pathway and has beneficial effects on memory and motility in CCH.

Neuroprotection by dimethyl fumarate following ventral root crush in C57BL/6J mice

CNS lesions usually result in permanent loss of function and are an important problem in the medical field. In order to investigate neuroprotection/degeneration mechanisms and the synaptic plasticity of motoneurons, in addition to the potential for a variety of treatments, different experimental models of axonal injury have been proposed. Recent studies have tested the immunomodulatory drug dimethyl fumarate (DMF) for the treatment of neurodegenerative diseases and have shown promising outcomes. Therefore, in this work, we investigated the effects of DMF with regard to neuroprotection and its influence on the glial response in C57BL/6J animals subjected to crushing of the motor roots in the lumbar intumescence of the spinal cord. The animals were divided into a vehicle-treated injury group (0.08 % methylcellulose solution control group, n = 7) and injured groups treated with DMF at different doses (15, 30, 45, 90 and 180 mg/kg; n = 6-7 per dose). The 90 mg/kg dose showed the best neuroprotective results, so it was used for treatment over a period of eight weeks. Neuronal survival was assessed through Nissl staining, and functional recovery was evaluated with the CatWalk system (walking track test) and the von Frey test (mechanoreception). Immunohistochemistry was used to assess synaptic coverage and astroglial and microglial reactivity using the primary antibodies anti-synaptophysin (pre-synaptic terminal pan marker), GAD65 (GABAergic pre-synaptic terminations - inhibitory), and VGLUT1 (glutamatergic pre-synaptic terminations - excitatory). Glial reactions were evaluated with anti-IBA1 (microglia) and GFAP (astrocytes). Gene transcript levels of IL-3, IL-4, TNF-α, IL-6, TGF-β, iNOS-M1, and arginase-M2 were quantified by RT-qPCR. The results indicated that treatment with DMF, at a dose of 90 mg/kg, promoted neuroprotection and immunomodulation towards an anti-inflammatory response. It also resulted in greater preservation of inhibitory synapses and reduced astroglial reactivity, providing a more favorable environment for sensorimotor recovery.

Dimethyl fumarate promotes B cell-mediated anti-inflammatory cytokine profile in B and T cells, and inhibits immune cell migration in patients with MS

Dimethyl Fumarate (DMF), known for its mechanism of action targeting Nrf2 and related redox homeostasis, is an approved immunotherapy for patients with Multiple Sclerosis (PwMS) in the relapsing form. We assessed how DMF modulates immune cell functions, namely the cytokine profile of co-cultured B and T cells, and the chemokine-mediated migration of immune cells. Following DMF therapy, LTα⁺, TNFα⁺ and IFNγ⁺ B cells were reduced while TGFβ and IL10 expression elevated. B cells from DMF-treated patients increased TGFβ and LTα expression on T cells, while DMF directly reduced TNFα⁺ and IFNγ⁺ T cells. CXCL12/CXCL13-mediated migration of B cells, Monocytes, CD4 and CD8 T cells was reduced, with altered CXCR5 and CXCR4 expression. Induction of regulatory B and T cells and reduced migration of immune cells may be part of the beneficial mechanism of DMF in PwMS.

Immunomodulation in multiple sclerosis: promises and pitfalls

Multiple sclerosis (MS) afflicts about 2.5 million people globally and poses a major personal and socioeconomic burden. The recognition of MS as an inflammatory disease, characterized by infiltration of immune cells into the central nervous system, has spurred research into the autoimmune etiology of the condition and has provided the rationale for its treatment through immunomodulation. Experience with immunotherapies in MS to date has suggested a disparity between the observed immune cell infiltration and the progressive loss of neurons. However, recent clinical efforts are providing new insights into progressive MS that once again place the immune system at center stage. This article reviews the main mechanisms of MS immunopathogenesis, and the benefits, risks and challenges of immunomodulatory treatments for the disease.

Anti-Psoriatic Drug Monomethylfumarate Increases Nuclear Factor Erythroid 2-Related Factor 2 Levels and Induces Aquaporin-3 mRNA and Protein Expression

Oxidative stress contributes to inflammatory skin diseases, including psoriasis. Monomethylfumarate (MMF) is an antipsoriatic agent with a poorly understood mechanism of action. In other cell types MMF increases the expression of nuclear factor erythroid-derived 2-like 2 (Nrf2), a transcription factor that regulates cellular antioxidant responses, to reduce oxidative stress like that observed in inflammatory disorders such as multiple sclerosis. We tested the hypothesis that MMF enhances Nrf2 activity in keratinocytes, thereby improving their capacity to counteract environmental stresses. We used Western analysis, immunofluorescence, and real-time quantitative reverse-transcription polymerase chain reaction to examine the effect of MMF on the expression of Nrf2 and its targets. We also measured intracellular reactive oxygen species (ROS) levels following MMF treatment. Our data show that MMF increased total and nuclear Nrf2 levels in primary mouse keratinocytes and enhanced mRNA expression of several Nrf2-downstream effectors, including heme oxygenase-1 and peroxiredoxin-6. Moreover, MMF treatment attenuated the generation of ROS following hydrogen peroxide treatment. On the other hand, the expression and membranous localization of aquaporin-3 (AQP3), a glycerol channel implicated in keratinocyte differentiation, was stimulated by MMF, which also enhanced keratinocyte glycerol uptake. The Nrf2 activator sulforaphane also increased AQP3 levels, suggesting that AQP3 expression may be regulated by Nrf2. We show for the first time that MMF stimulates Nrf2 and AQP3 expression and function/activity in keratinocytes. This effect may account, in part, for the previously observed ability of MMF to inhibit proliferation and inflammatory mediator production and promote differentiation in keratinocytes and to treat psoriasis.

Multiple sclerosis: Therapeutic applications of advancing drug delivery systems

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system, which is accompanying with demyelination, neurodegeneration and sensibility to oxidative stress. In MS, auto-reactive lymphocytes cross the blood-brain barrier (BBB) and reside in the perivenous demyelinating lesions which create various distinct inflammatory demyelinated plaques situated predominantly in the white matter. The current MS-related therapeutic approaches can be classified into disease-modifying therapies (DMTs) and symptomatic therapy. DMTs suppress circulating immune cells, inhibit passing the BBB and decrease the inflammatory responses. Recent advances have remarkably delayed disease development and improved the quality of life for numerous patients. In spite of major improvements in therapeutic options, there are some limitations regarding the routes of administration and the necessity for repeated and long-term dosing in which cause to systemic disadvantageous consequences and patient non-compliance. Nanotechnology presents promising approaches to improve autoimmune disease treatment with the capability to overcome many of the limitations common to the current immunosuppressive and biological therapies. Here we emphasis on nanomedicine-based drug delivery approaches of biological immunomodulatory mediators for the treatment of multiple sclerosis. This comprehensive review details the most successful drugs in MS therapy and also focuses on conceptions and clinical potential of novel nanomedicine attitudes for inducing immunosuppression and immunological tolerance in MS to modulate abnormal and pathologic immune responses.

Dimethyl Fumarate and Monomethyl Fumarate Promote Post-Ischemic Recovery in Mice

Oxidative stress plays an important role in cerebral ischemia-reperfusion injury. Dimethyl fumarate (DMF) and its primary metabolite monomethyl fumarate (MMF) are antioxidant agents that can activate the nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and induce the expression of antioxidant proteins. Here, we evaluated the impact of DMF and MMF on ischemia-induced brain injury and whether the Nrf2 pathway mediates the effects provided by DMF and MMF in cerebral ischemia-reperfusion injury. Using a mouse model of transient focal brain ischemia, we show that DMF and MMF significantly reduce neurological deficits, infarct volume, brain edema, and cell death. Further, DMF and MMF suppress glial activation following brain ischemia. Importantly, the protection of DMF and MMF was mostly evident during the subacute stage and was abolished in Nrf2-/- mice, indicating that the Nrf2 pathway is required for the beneficial effects of DMF and MMF. Together, our data indicate that DMF and MMF have therapeutic potential in cerebral ischemia-reperfusion injury and their protective role is likely mediated by the Nrf2 pathway.

Dimethyl fumarate blocks pro-inflammatory cytokine production via inhibition of TLR induced M1 and K63 ubiquitin chain formation

Dimethyl fumarate (DMF) possesses anti-inflammatory properties and is approved for the treatment of psoriasis and multiple sclerosis. While clinically effective, its molecular target has remained elusive - although it is known to activate anti-oxidant pathways. We find that DMF inhibits pro-inflammatory cytokine production in response to TLR agonists independently of the Nrf2-Keap1 anti-oxidant pathway. Instead we show that DMF can inhibit the E2 conjugating enzymes involved in K63 and M1 polyubiquitin chain formation both in vitro and in cells. The formation of K63 and M1 chains is required to link TLR activation to downstream signaling, and consistent with the block in K63 and/or M1 chain formation, DMF inhibits NFκB and ERK1/2 activation, resulting in a loss of pro-inflammatory cytokine production. Together these results reveal a new molecular target for DMF and show that a clinically approved drug inhibits M1 and K63 chain formation in TLR induced signaling complexes. Selective targeting of E2s may therefore be a viable strategy for autoimmunity.

Immunological treatment of multiple sclerosis

Treatment of multiple sclerosis (MS) has been a challenge since its first description by Charcot. The advent of immunomodulatory drugs in the mid 1990s brought the first big change in the treatment of MS patients. During the last 10 years there has been an ongoing tremendous evolution of novel treatment options for relapsing-remitting MS. These options include monoclonal antibodies, which inhibit migration of lymphocytes (natalizumab), deplete lymphocytes (alemtuzumab), or block the cytokine receptor interleukin (IL)-2 (daclizumab), teriflunomide that inhibits proliferation of activated lymphocytes, fingolimod that modulates the sphingosine-receptor system, and dimethylfumarate that combines features of immunomodulatory and immunosuppressive drugs. The topic of this review is to discuss currently available treatments and provide an outlook into the near future.

Multiple rodent models and behavioral measures reveal unexpected responses to FTY720 and DMF in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a widely-used rodent model for multiple sclerosis (MS), but a single model can hardly capture all features of MS. We investigated whether behavioral parameters in addition to clinical motor function scores could be used to assess treatment efficacy during score-free intervals in the relapsing-remitting EAE model in SJL/J mice. We studied the effects of the clinical reference compounds FTY720 (fingolimod, 0.5mg/kg/day) and dimethyl fumarate (DMF, 20-30 mg/kg/day) on clinical scores in several rodent EAE models in order to generate efficacy profiles. SJL/J mice with relapsing-remitting EAE were studied using behavioral tests, including rotarod, gait analysis, locomotor activity and grip strength. SJL/J mice were also examined according to Crawley's sociability and preference for social novelty test. Prophylactic treatment with FTY720 prevented clinical scores in three of the four EAE rodent models: Dark Agouti (DA) and Lewis rats and C57BL/6J mice. Neither prophylactic nor late-therapeutic treatment with FTY720 reduced clinical scores or reversed deficits in the rotarod test in SJL/J mice, but we observed effects on motor functions and sociability in the absence of clinical scores. Prophylactic treatment with FTY720 improved the gait of SJL/J mice whereas late-therapeutic treatment improved manifestations of reduced social (re)cognition or preference for social novelty. DMF was tested in three EAE models and did not improve clinical scores at the dose used. These data indicate that improvements in behavioral deficits can occur in absence of clinical scores, which indicate subtle drug effects and may have translational value for human MS.

Dimethyl fumarate in relapsing-remitting multiple sclerosis: rationale, mechanisms of action, pharmacokinetics, efficacy and safety

Dimethyl fumarate (DMF), a fumaric acid ester, is a new orally available disease-modifying agent that was recently approved by the US FDA and the EMA for the management of relapsing forms of multiple sclerosis (MS). Fumaric acid has been used for the management of psoriasis, for more than 50 years. Because of the known anti-inflammatory properties of fumaric acid ester, DMF was brought into clinical development in MS. More recently, neuroprotective and myelin-protective mechanism actions have been proposed, making it a possible candidate for MS treatment. Two Phase III clinical trials (DEFINE, CONFIRM) have evaluated the safety and efficacy of DMF in patients with relapsing-remitting MS. Being an orally available agent with a favorable safety profile, it has become one of the most commonly prescribed disease-modifying agents in the USA and Europe.

Dimethyl fumarate-associated lymphopenia: Risk factors and clinical significance

BACKGROUND

Dimethyl fumarate (DMF), a disease-modifying therapy for multiple sclerosis (MS), causes lymphopenia in a fraction of patients. The clinical significance of this is unknown. Several cases of progressive multifocal leukoencephalopathy in lymphopenic fumarate-treated patients have raised concerns about drug safety. Since lymphocytes contribute to MS pathology, lymphopenia may also be a biomarker for response to the drug.

OBJECTIVE

The objective of this manuscript is to evaluate risk factors for DMF-induced lymphopenia and drug failure in a real-world population of MS patients.

METHODS

We conducted a retrospective cohort study of 221 patients prescribed DMF at a single academic medical center between March 2013 and February 2015.

RESULTS

Grade 2-3 lymphopenia developed in 17% of the total cohort and did not resolve during DMF treatment. Older age (>55), lower baseline absolute lymphocyte count and recent natalizumab exposure increased the risk of developing moderate to severe lymphopenia while on DMF. Lymphopenia was not predictive of good clinical response or of breakthrough MS activity on DMF.

CONCLUSIONS

Lymphopenia develops in a significant minority of DMF-treated patients, and if grade 2 or worse, is unlikely to resolve while on the drug. Increased vigilance in lymphocyte monitoring and infection awareness is particularly warranted in older patients and those switching from natalizumab.

Dimethyl fumarate-associated lymphopenia: Risk factors and clinical significance

BACKGROUND

Dimethyl fumarate (DMF), a disease-modifying therapy for multiple sclerosis (MS), causes lymphopenia in a fraction of patients. The clinical significance of this is unknown. Several cases of progressive multifocal leukoencephalopathy in lymphopenic fumarate-treated patients have raised concerns about drug safety. Since lymphocytes contribute to MS pathology, lymphopenia may also be a biomarker for response to the drug.

OBJECTIVE

The objective of this manuscript is to evaluate risk factors for DMF-induced lymphopenia and drug failure in a real-world population of MS patients.

METHODS

We conducted a retrospective cohort study of 221 patients prescribed DMF at a single academic medical center between March 2013 and February 2015.

RESULTS

Grade 2-3 lymphopenia developed in 17% of the total cohort and did not resolve during DMF treatment. Older age (>55), lower baseline absolute lymphocyte count and recent natalizumab exposure increased the risk of developing moderate to severe lymphopenia while on DMF. Lymphopenia was not predictive of good clinical response or of breakthrough MS activity on DMF.

CONCLUSIONS

Lymphopenia develops in a significant minority of DMF-treated patients, and if grade 2 or worse, is unlikely to resolve while on the drug. Increased vigilance in lymphocyte monitoring and infection awareness is particularly warranted in older patients and those switching from natalizumab.

Advances in the management of relapsing-remitting multiple sclerosis: role of oral dimethyl fumarate (BG-12)

Multiple sclerosis is a complex and chronic inflammatory disease of the central nervous system which affects an estimated 2.3 million individuals worldwide. Genetic research has uncovered over 100 immune-related genes associated with the disease and has provided a multitude of potential therapeutic targets. To date, 13 US Food and Drug Administration-approved disease-modifying therapies designed to influence the aberrant immune system are available for the indication of relapsing forms of the disease. BG-12 is a novel oral multiple sclerosis therapeutic with a unique putative mechanism of action that activates the Nrf2 anti-oxidant pathway. Despite the enthusiasm for multiple therapeutic options, including oral options, the practitioner is faced with the difficult task of providing guidance for patients regarding optimal sequencing of therapeutics without sensitive clinical biomarkers to match a particular therapy’s putative mechanism of action to the patient’s specific pathophysiology. Moreover, while BG-12 has a preferred route of administration, there is limited safety data with which to guide counseling in the clinic. Dimethyl fumarate (DMF or BG-12) is one of three available oral therapies which will be discussed in this review in terms of its pharmacokinetic profile, putative mechanism of action, clinical effectiveness, safety, tolerance, and patient-reported experience. BG-12’s potential as a first-line therapy and as a sequencing therapeutic to aid in transition off natalizumab will be discussed.

Dimethyl fumarate in the treatment of relapsing-remitting multiple sclerosis: an overview

Multiple sclerosis (MS) shares an immune-mediated origin with psoriasis. Long-term safety and efficacy data generated in Europe from usage of fumaric acid formulations in the latter disease constituted grounds to investigate their effects in MS patients. Dimethyl fumarate (DMF) was found to be the active principle in those formulations and in vitro studies have demonstrated that DMF has immune-modulatory properties exerted through abilities to divert cytokine production toward a Th2 profile, both on lymphocytes and microglial cells. More importantly, DMF was discovered to impact the anti-oxidative stress cell machinery promoting the transcription of genes downstream to the activation of the nuclear factor (erythroid derived 2)-like2 (NRF2). DMF exposure increases the cytosol concentrations of NRF2, which besides immune regulatory effects, has the potential for cytoprotection on glial cells, oligodendrocytes and neurons. Extensive and rigorous clinical trials have assessed the efficacy and safety of DMF at the dose of 240 mg twice and three times a day in relapsing-remitting MS patients during one phase IIb and two phase III trials. Robust, positive results were obtained across a number of clinical and paraclinical parameters. In one study (DEFINE), the relative reductions of the adjusted annualized relapse rate of the low and high dose regimens in comparison with placebo were 53% and 48%, respectively (p < 0.001 for both comparisons). In the other trial (CONFIRM), DMF decreased the annualized relapse rate in comparison with placebo by 44% in the lower and by 51% in higher dosage group (also p < 0.001). The number and size of lesions as detected by magnetic resonance imaging were also significantly decreased in comparison with the patients receiving DMF at every dosage. Multiple post hoc and subgroup analyses corroborated the clinical data, rendering DMF an appealing medication whose potential for impacting the degenerative aspects of MS remains to be explored.

The antipsoriatic agent monomethylfumarate has antiproliferative, prodifferentiative, and anti-inflammatory effects on keratinocytes

Monomethylfumarate (MMF) is thought to be the bioactive ingredient of the drug Fumaderm (Biogen Idec, Cambridge, MA), licensed in Germany since 1994 for the treatment of moderate-to-severe psoriasis. Psoriasis is a common inflammatory hyperproliferative skin disorder that involves cross-talk between different cell types, including immune cells and keratinocytes. Psoriatic lesions are characterized by hyperproliferation, aberrant differentiation, and inflammation, with the psoriatic cytokine network maintained by communication between immune cells and keratinocytes. Recently, there is increasing evidence regarding the pivotal role of keratinocytes in mediating the disease process, and these cells can be regarded as safe therapeutic targets. From the data available on human subjects treated with Fumaderm, MMF is an effective antipsoriatic agent with known effects on immune cells. However, little is known about its direct effects on keratinocytes. We hypothesized that MMF has direct antiproliferative, prodifferentiative, and anti-inflammatory effects on keratinocytes. Indeed, MMF dose-dependently inhibited [(3)H]thymidine incorporation into DNA, indicating a direct antiproliferative action on keratinocytes. MMF significantly increased the protein level of keratin 10, the early keratinocyte differentiation marker, and the activity of transglutaminase, a late differentiation marker. These results are consistent with an ability of MMF to promote keratinocyte differentiation and inhibit proliferation, thereby improving psoriatic lesions. In 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced keratinocytes, MMF significantly inhibited the expression of the proinflammatory cytokines, tumor necrosis factor-α (TNFα), interleukin-6, and interleukin-1α as well as the production of TNFα. Our results support the notion that MMF has direct antiproliferative, prodifferentiative, and anti-inflammatory effects on keratinocytes, highlighting its potential use as a multifactorial antipsoriatic agent.