Dimethylfumarate inhibits tumor-necrosis-factor-induced CD62E expression in an NF-kappa B-dependent manner

Repurposing Dimethyl Fumarate for Cardiovascular Diseases: Pharmacological Effects, Molecular Mechanisms, and Therapeutic Promise

Dimethyl fumarate (DMF) is a small molecule that has been shown to assert potent in vivo immunoregulatory and anti-inflammatory therapeutic actions. The drug has been approved and is currently in use for treating multiple sclerosis and psoriasis in the USA and Europe. Since inflammatory reactions have been significantly implicated in the etiology and progression of diverse disease states, the pharmacological actions of DMF are presently being explored and generalized to other diseases where inflammation needs to be suppressed and immunoregulation is desirable, either as a monotherapeutic agent or as an adjuvant. In this review, we focus on DMF, and present an overview of its mechanism of action while briefly discussing its pharmacokinetic profile. We further discuss in detail its pharmacological uses and highlight its potential applications in the treatment of cardiovascular diseases. DMF, with its unique combination of anti-inflammatory and vasculoprotective effects, has the potential to be repurposed as a therapeutic agent in patients with atherosclerotic cardiovascular disease. The clinical studies mentioned in this review with respect to the beneficial effects of DMF in atherosclerosis involve observations in patients with multiple sclerosis and psoriasis in small cohorts and for short durations. The findings of these studies need to be assessed in larger prospective clinical trials, ideally with a double-blind randomized study design, investigating the effects on cardiovascular endpoints as well as morbidity and mortality. The long-term impact of DMF therapy on cardiovascular diseases also needs to be confirmed.

Dimethyl fumarate inhibits antibody-induced platelet destruction in immune thrombocytopenia mouse

BACKGROUND

Immune thrombocytopenia (ITP) is an autoimmune disease characterized as a low platelet count resulting from immune-mediated platelet destruction. Dimethyl fumarate (DMF) is widely applied for the treatment of several autoimmune diseases with immunosuppressive effect. However, whether it ameliorates ITP is unclear. This study aims to evaluate whether DMF has a preventive effect on ITP in mice.

METHODS

DMF (30, 60 or 90 mg/kg body weight) was intraperitoneally injected into mice followed by injection of rat anti-mouse integrin GPIIb/CD41antibody to induce ITP. Peripheral blood was isolated to measure platelet count and spleen mononuclear cells were extracted to measure Th1 and Treg cells along with detecting the levels of IFN-γ, and TGFβ-1 in plasma and CD68 expression in spleen by immuohistochemical staining. Additionally, macrophage cell line RAW264.7 was cultured and treated with DMF followed by analysis of cell apoptosis and cycle, and the expression of FcγRI, FcγRIIb and FcγRIV mRNA.

RESULTS

DMF significantly inhibited antiplatelet antibody-induced platelet destruction, decreased Th1 cells and the expression of T-bet and IFN-γ, upregulated Treg cells and the expression of Foxp3 and TGF-β1 as well as reduced CD68 expression in the spleen of ITP mouse. DMF-treated RAW264.7 cells showed S-phase arrest, increased apoptosis and downregulated expression of FcγRI and FcγRIV. Meanwhile, in vitro treatment of DMF also decreased the expression of cyclin D1 and E2, reduced Bcl-2 level and increased Bax expression and caspase-3 activation.

CONCLUSIONS

In conclusion, DMF prevents antibody-mediated platelet destruction in ITP mice possibly through promoting apoptosis, indicating that it might be used as a new approach for the treatment of ITP.

Dimethyl fumarate induced lymphopenia in multiple sclerosis: A review of the literature

Dimethyl fumarate (DMF) is a first line medication for multiple sclerosis. It has a favourable safety profile, however, there is concern regarding the occurrence of moderate-severe and sustained lymphopenia and the associated risk of progressive multifocal leukoencephalopathy. We carried out an extensive literature review to understand the molecular mechanisms underlying this adverse reaction. Dynamic changes in certain components of the immune system are likely to be important for the therapeutic effects of DMF, including depletion of memory T cells and decrease in activated T cells together with expansion of naïve T cells. Similar modifications were reported for the B cell components. CD8⁺ T cells are particularly susceptible to DMF-induced cell death, with marked reductions observed in lymphopenic subjects. The reasons underlying such increased sensitivity are not known, nor it is known how expansion of other lymphocyte subsets occurs. Understanding the molecular mechanisms underlying DMF action is challenging: in vivo DMF is rapidly metabolized to monomethyl fumarate (MMF), a less potent immunomodulator in vitro. Pharmacokinetics indicate that MMF is the main active species in vivo. However, the relative importance of DMF and MMF in toxicity remains unclear, with evidence presented in favour of either of the compounds as toxic species. Pharmacogenetic studies to identify genetic predictors of DMF-induced lymphopenia are limited, with inconclusive results. A role of the gut microbiome in the pharmacological effects of DMF is emerging. It is clear that further investigations are necessary to understand the mechanisms of DMF-induced lymphopenia and devise preventive strategies. Periodic monitoring of absolute lymphocyte counts, currently performed in clinical practise, allows for the early detection of lymphopenia as a risk-minimization strategy.

Small Molecule NF-κB Pathway Inhibitors in Clinic

Nuclear factor kappa B (NF-κB) signaling is implicated in all major human chronic diseases, with its role in transcription of hundreds of gene well established in the literature. This has propelled research into targeting the NF-κB pathways for modulating expression of those genes and the diseases mediated by them. In-spite of the critical, but often promiscuous role played by this pathway and the inhibition causing adverse drug reaction, currently many biologics, macromolecules, and small molecules that modulate this pathway are in the market or in clinical trials. Furthermore, many marketed drugs that were later found to also have NF-κB targeting activity were repurposed for new therapeutic interventions. Despite the rising importance of biologics in drug discovery, small molecules got around 76% of US-FDA (Food and Drug Administration-US) approval in the last decade. This encouraged us to review information regarding clinically relevant small molecule inhibitors of the NF-κB pathway from cell surface receptor stimulation to nuclear signaling. We have also highlighted the underexplored targets in this pathway that have potential to succeed in clinic.

Metabolomic Profile of Posner-Schlossman Syndrome: A Gas Chromatography Time-of-Flight Mass Spectrometry-Based Approach Using Aqueous Humor

The Posner-Schlossman syndrome (PSS) is a disease with clinically recurrent unilateral anterior uveitis with markedly elevated intraocular pressure (IOP) and subsequent progression to optic neuropathy. Retrospective studies have reported increased annual incidence of PSS, especially in China. While currently, the clinical management of PSS is still challenging. Metabolomics is considered to be a sensitive approach for the development of novel targeted therapeutics because of its direct elucidation of pathophysiological mechanisms. Therefore, we adopted gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) technology-based non-targeted metabolomics approach to measure comprehensive metabolic profiles of aqueous humor (AH) samples obtained from patients with PSS, with an aim to demonstrate the underlying pathophysiology, identify potential biomarkers specific to PSS, and develop effective treatment strategies. A comparative analysis was used to indicate the distinct metabolites of PSS. Pathway analysis was conducted using MetaboAnalyst 4.0 to explore the metabolic reprogramming pathways involved in PSS. Logistic regression and receiver-operating characteristic (ROC) analyses were employed to evaluate the diagnostic capability of selected metabolites. Comparative analysis revealed a clear separation between PSS and control groups. Fourteen novel differentiating metabolites from AH samples obtained from patients with PSS were highlighted. Pathway analysis identified 11 carbohydrate, amino acid metabolism and energy metabolism pathways as the major disturbed pathways associated with PSS. The abnormal lysine degradation metabolism, valine-leucine-isoleucine biosynthesis, and citrate circle were considered to weigh the most in the development of PSS. The ROC analysis implied that the combination of glycine and homogentisic acid could serve as potential biomarkers for the discrimination of control and PSS groups. In conclusion, these results revealed for the first time the identity of important metabolites and pathways contributing to the development/progression of PSS, enabled the better understanding of the mechanism of PSS, and might lead to the development of metabolic biomarkers and novel therapeutic strategies to restrict the development/progression of PSS.

Lymphocyte Count and Body Mass Index as Biomarkers of Early Treatment Response in a Multiple Sclerosis Dimethyl Fumarate-Treated Cohort

Introduction: In relapsing Multiple Sclerosis (RMS) patients treated with disease modifying drugs (DMDs), few data are available regarding the biomarkers of treatment response. We aimed to assess the predictive value of lymphocyte count (LC) and Body Mass Index (BMI) for treatment response in a real life setting of dimethyl fumarate (DMF) treated patients. Materials and Methods: We included in our observational analysis 338 patients who were prescribed DMF in an Italian MS Center. We collected clinical and demographic data at the beginning of DMF (T0), and assessed White Blood Cells (WBC) and LC at T0 and at 3 (T3), 6 (T6), 9 (T9), and 12 (T12) months. Gadolinium enhancing (Gd+), new T2 lesions and relapses within the first year of treatment (T12) were recorded in order to evaluate clinical activity at 12 months. Analysis of correlation was performed to correlate WBC, LC and BMI with clinical and radiological responses. We evaluated whether BMI or LC can predict treatment response by using multivariate logistic regression models at each follow-up. Results: Our cohort was followed up for a mean period of 19.8 ± 6.8 months. The mean BMI at baseline was 24.19 ± 4.48. The multivariate models gave as predictive factors for Gd+ lesions at T12, LC at T3 (OR = 1.003, 95% CI = 1.00-1.07; p = 0.046) and baseline BMI (OR = 0.71, 95% CI = 0.52-0.98; p = 0.037). Predictive factors for new T2 lesions at T12 were LC at T3 (OR = 1.01 95%CI = 1.00-1.95; p = 0.005) and baseline BMI (OR = 0.99, 95% CI = 0.98-1.00; p = 0.026). Conclusions: In our real life-experience, BMI and LC may be early biomarkers to predict treatment response during DMF.

Dimethyl Fumarate Disrupts Human Innate Immune Signaling by Targeting the IRAK4-MyD88 Complex

Dimethyl fumarate (DMF) is a prescribed treatment for multiple sclerosis and has also been used to treat psoriasis. The electrophilicity of DMF suggests that its immunosuppressive activity is related to the covalent modification of cysteine residues in the human proteome. Nonetheless, our understanding of the proteins modified by DMF in human immune cells and the functional consequences of these reactions remains incomplete. In this study, we report that DMF inhibits human plasmacytoid dendritic cell function through a mechanism of action that is independent of the major electrophile sensor NRF2. Using chemical proteomics, we instead identify cysteine 13 of the innate immune kinase IRAK4 as a principal cellular target of DMF. We show that DMF blocks IRAK4-MyD88 interactions and IRAK4-mediated cytokine production in a cysteine 13-dependent manner. Our studies thus identify a proteomic hotspot for DMF action that constitutes a druggable protein-protein interface crucial for initiating innate immune responses.

Chemical and genetic control of IFNγ-induced MHCII expression

The cytokine interferon-γ (IFNγ) can induce expression of MHC class II (MHCII) on many different cell types, leading to antigen presentation to CD4⁺ T cells and immune activation. This has also been linked to anti-tumour immunity and graft-versus-host disease. The extent of MHCII upregulation by IFNγ is cell type-dependent and under extensive control of epigenetic regulators and signalling pathways. Here, we identify novel genetic and chemical factors that control this form of MHCII expression. Loss of the oxidative stress sensor Keap1, autophagy adaptor p62/SQSTM1, ubiquitin E3-ligase Cullin-3 and chromatin remodeller BPTF impair IFNγ-mediated MHCII expression. A similar phenotype is observed for arsenite, an oxidative stressor. Effects of the latter can be reversed by the inhibition of HDAC1/2, linking oxidative stress conditions to epigenetic control of MHCII expression. Furthermore, dimethyl fumarate, an antioxidant used for the treatment of several autoimmune diseases, impairs the IFNγ response by manipulating transcriptional control of MHCII We describe novel pathways and drugs related to oxidative conditions in cells impacting on IFNγ-mediated MHCII expression, which provide a molecular basis for the understanding of MHCII-associated diseases.

Mononuclear cell transcriptome changes associated with dimethyl fumarate in MS

Objective

To identify short-term changes in gene expression in peripheral blood mononuclear cells (PBMCs) associated with treatment response to dimethyl fumarate (DMF, Tecfidera) in patients with relapsing-remitting MS (RRMS).

Methods

Blood samples were collected from 24 patients with RRMS (median Expanded Disability Status Scale score, 2.0; range 1–7) at baseline, 6 weeks, and 15 months after the initiation of treatment with DMF (BG-12; Tecfidera). Seven healthy controls were also recruited, and blood samples were collected over the same time intervals. PBMCs were extracted from blood samples and sequenced using next-generation RNA sequencing. Treatment responders were defined using the composite outcome measure “no evidence of disease activity” (NEDA-4). Time-course and cross-sectional differential expression analyses were performed to identify transcriptomic markers of treatment response.

Results

Treatment responders (NEDA-4 positive, 8/24) over the 15-month period had 478 differentially expressed genes (DEGs) 6 weeks after the start of treatment. These were enriched for nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and inhibition of nuclear factor κB (NFκB) pathway transcripts. For patients who showed signs of disease activity, there were no DEGs at 6 weeks relative to their (untreated) baseline. Contrasting transcriptomes expressed at 6 weeks with those at 15 months of treatment, 0 and 1,264 DEGs were found in the responder and nonresponder groups, respectively. Transcripts in the nonresponder group (NEDA-4 negative, 18/24) were enriched for T-cell signaling genes.

Conclusion

Short-term PBMC transcriptome changes reflecting activation of the Nrf2 and inhibition of NFκB pathways distinguish patients who subsequently show a medium-term treatment response with DMF. Relative stabilization of gene expression patterns may accompany treatment-associated suppression of disease activity.

What's new about oral treatments in Multiple Sclerosis? Immunogenetics still under question

Multiple Sclerosis (MS) is a chronic pathology affecting the Central Nervous System characterized by inflammatory processes that lead to demyelination and neurodegeneration. In MS treatment, disease modifying therapies (DMTs) are essential to reduce disease progression by suppressing the inflammatory response responsible for promoting lesion formation. Recently, in addition to the classical injectable DMTs like Interferons and Glatiramer acetate, new orally administered drugs have been approved for MS therapy: dimethyl fumarate, teriflunomide and fingolimod. These drugs act with different mechanisms on the immune system, in order to suppress the harmful inflammatory process. An additional layer of complexity is introduced by the influence of polymorphic gene variants in the Human Leukocyte Antigen region on the risk of developing MS and its progression. To date, pharmacogenomic studies have mainly focused on the patient's response following admission of injectable drugs. Therefore, greater consideration must be made to pharmacogenomics with a view to developing more effective and personalized therapies. This review aims to shed light on the mechanism of action of the new oral drugs dimethyl fumarate, teriflunomide and fingolimod, taking into account both the importance of immunogenetics in drug response and pharmacogenomic studies.

Chemical proteomic map of dimethyl fumarate-sensitive cysteines in primary human T cells

Dimethyl fumarate (DMF) is an electrophilic drug that is used to treat autoimmune conditions, including multiple sclerosis and psoriasis. The mechanism of action of DMF is unclear but may involve the covalent modification of proteins or DMF serving as a prodrug that is converted to monomethyl fumarate (MMF). We found that DMF, but not MMF, blocked the activation of primary human and mouse T cells. Using a quantitative, site-specific chemical proteomic platform, we determined the DMF sensitivity of >2400 cysteine residues in human T cells. Cysteines sensitive to DMF, but not MMF, were identified in several proteins with established biochemical or genetic links to T cell function, including protein kinase Cθ (PKCθ). DMF blocked the association of PKCθ with the costimulatory receptor CD28 by perturbing a CXXC motif in the C2 domain of this kinase. Mutation of these DMF-sensitive cysteines also impaired PKCθ-CD28 interactions and T cell activation, designating the C2 domain of PKCθ as a key functional, electrophile-sensing module important for T cell biology.

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.

Dimethyl fumarate restores apoptosis sensitivity and inhibits tumor growth and metastasis in CTCL by targeting NF-κB

Despite intensive efforts in recent years, a curative therapy for cutaneous T-cell lymphoma (CTCL) has not yet been developed. Therefore, the establishment of new therapeutic approaches with higher efficacy rates and milder side effects is strongly desired. A characteristic feature of the malignant T-cell population in CTCL is resistance toward cell death resulting from constitutive NF-κB activation. Therefore, NF-κB-dependent cell death resistance represents an interesting therapeutic target in CTCL because an NF-κB-directed therapy would leave bystander T cells widely unaffected. We investigated the effects of dimethyl fumarate (DMF) on CTCL cells in vitro and in vivo. DMF induced cell death in primary patient-derived CD4(+) cells and CTCL cell lines, but hardly in T cells from healthy donors. DMF-induced cell death was linked specifically to NF-κB inhibition. To study the impact of DMF in vivo, we developed 2 CTCL xenograft mouse models with different cutaneous localizations of the T-cell infiltrate. DMF treatment delayed the growth of CTCL tumors and prevented formation of distant metastases. In addition, DMF induced increased cell death in primary CTCL tumors and in liver metastases. In summary, DMF treatment represents a remarkable therapeutic option in CTCL because it restores CTCL apoptosis in vitro and in preclinical models in vivo and prevents spreading of the disease to distant sites. DMF treatment is of particular promise in CTCL because DMF is already in successful clinical use in the treatment of psoriasis and multiple sclerosis allowing fast translation into clinical studies in CTCL.

Dimethylfumarate Impairs Neutrophil Functions

Host defense against pathogens relies on neutrophil activation. Inadequate neutrophil activation is often associated with chronic inflammatory diseases. Neutrophils also constitute a significant portion of infiltrating cells in chronic inflammatory diseases, for example, psoriasis and multiple sclerosis. Fumarates improve the latter diseases, which so far has been attributed to the effects on lymphocytes and dendritic cells. Here, we focused on the effects of dimethylfumarate (DMF) on neutrophils. In vitro, DMF inhibited neutrophil activation, including changes in surface marker expression, reactive oxygen species production, formation of neutrophil extracellular traps, and migration. Phagocytic ability and autoantibody-induced, neutrophil-dependent tissue injury ex vivo was also impaired by DMF. Regarding the mode of action, DMF modulates-in a stimulus-dependent manner-neutrophil activation using the phosphoinositide 3-kinase/Akt-p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 pathways. For in vivo validation, mouse models of epidermolysis bullosa acquisita, an organ-specific autoimmune disease caused by autoantibodies to type VII collagen, were employed. In the presence of DMF, blistering induced by injection of anti-type VII collagen antibodies into mice was significantly impaired. DMF treatment of mice with clinically already-manifested epidermolysis bullosa acquisita led to disease improvement. Collectively, we demonstrate a profound inhibitory activity of DMF on neutrophil functions. These findings encourage wider use of DMF in patients with neutrophil-mediated diseases.

Protective effects of monomethyl fumarate at the inflamed blood-brain barrier

BACKGROUND

Reactive oxygen species play a key role in the pathogenesis of multiple sclerosis as they induce blood-brain barrier disruption and enhance transendothelial leukocyte migration. Thus, therapeutic compounds with antioxidant and anti-inflammatory potential could have clinical value in multiple sclerosis. The aim of the current study was to elucidate the therapeutic effects of monomethyl fumarate on inflammatory-mediated changes in blood-brain barrier function and gain insight into the underlying mechanism.

METHODS

The effects of monomethyl fumarate on monocyte transendothelial migration across and adhesion to inflamed human brain endothelial cells (hCMEC/D3) were quantified using standardized in vitro migration and adhesion assays. Flow cytometry analysis and qPCR were used to measure the concomitant effects of monomethyl fumarate treatment on protein expression of cell adhesion molecules. Furthermore, the effects of monomethyl fumarate on the expression and nuclear localization of proteins involved in the activation of antioxidant and inflammatory pathways in human brain endothelial cells were elucidated using nuclear fractionation and Western blotting. Statistical analysis was performed using one-way ANOVA followed by the Bonferroni post-hoc test.

RESULTS

Our results show that monomethyl fumarate induced nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 and concomitant production of the antioxidant enzymes heme oxygenase-1 and NADPH:quinone oxidoreductase-1 in brain endothelial cells. Importantly, monomethyl fumarate treatment markedly decreased monocyte transendothelial migration across and adhesion to inflamed human brain endothelial cells. Treatment of brain endothelial cells with monomethyl fumarate resulted in a striking reduction of vascular cell adhesion molecule expression. Surprisingly, monomethyl fumarate did not affect nuclear translocation of nuclear factor-кB suggesting that monomethyl fumarate potentially affects activity of nuclear factor-ĸB downstream of nuclear translocation.

CONCLUSIONS

Taken together, we show that monomethyl fumarate, the primary metabolite of dimethyl fumarate, which is currently used in the clinics for the treatment of relapsing-remitting multiple sclerosis, demonstrates beneficial therapeutic effects at the inflamed blood-brain barrier.

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.

Dimethylfumarate protects against TNF-α-induced secretion of inflammatory cytokines in human endothelial cells

Background

Inflammation, angiogenesis and oxidative stress have been implicated in the pathogenesis of various vascular diseases. Recent evidence suggests that dimethylfumarate (DMF), an antiposriatic and anti-multiple sclerosis agent, possesses anti-inflammatory, anti-oxidative and anti-angiogenic properties. Here, we analyze the influence of DMF on TNF-α-induced expression of the important pro-inflammatory and pro-atherogenic chemokine MCP-1 and investigate the underlying mechanisms of this expression.

Findings

We analyzed constitutive and TNF-α-induced expression of MCP-1 in human umbilical vascular endothelial cells (HUVEC) +/− DMF treatment via enzyme-linkes immunosorbent assay (ELISA). DMF significantly inhibited the protein expression levels in a time- and concentration-dependent manner. Furthermore, MCP-1 mRNA expression was also reduced in response to DMF, as demonstrated by RT-PCR. Thus, the regulation occurs at the transcriptional level. Interestingly, DMF prolonged the TNF-α-induced p38 and JNK phosphorylation in HUVEC, as demonstrated by Western blot analysis; however, the p38 and JNK inhibitor SB203580 did not affect the DMF-conveyed suppression of TNF-α-induced MCP-1 expression. DMF suppressed the TNF-α-induced nuclear translocation and phosphorylation (Serine 536) of p65 in these cells. These results were additionally approved by p65 luciferase promoter assays. Furthermore, we found that DMF slightly inhibited the early degradation of IκBα. In addition, we verified our results using other important inflammatory cytokines such as CCL-5, PDGF-BB, GM-CSF and IL-6.

Conclusion

DMF suppresses various TNF-α-induced pro-inflammatory and pro-atherogenic cytokines/chemokines in human endothelial cells. This action is regulated by reduced p65 activity and nuclear translocation, which can be explained in part by the reduced early degradation of IκBα and more important the reduced phosphorylation of p65 at Serine 536. These effects were independent of the p38, PI3K and p42/44 signaling pathways. As a result, DMF might be suitable for treating patients with vascular diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-015-0094-z) contains supplementary material, which is available to authorized users.

DMF, but not other fumarates, inhibits NF-κB activity in vitro in an Nrf2-independent manner

Fumarate-containing pharmaceuticals are potent therapeutic agents that influence multiple cellular pathways. Despite proven clinical efficacy, there is a significant lack of data that directly defines the molecular mechanisms of action of related, yet distinct fumarate compounds. We systematically compared the impact of dimethyl fumarate (DMF), monomethyl fumarate (MMF) and a mixture of monoethyl fumarate salts (Ca(++), Mg(++), Zn(++); MEF) on defined cellular responses. We demonstrate that DMF inhibited NF-κB-driven cytokine production and nuclear translocation of p65 and p52 in an Nrf2-independent manner. Equivalent doses of MMF and MEF did not affect NF-κB signaling. These results highlight a key difference in the biological impact of related, yet distinct fumarate compounds.

Oral disease-modifying therapies for multiple sclerosis

Classical multiple sclerosis (MS) treatments using first-line injectable drugs, although widely applied, remain a major concern in terms of therapeutic adherence and efficacy. New oral drugs recently approved for MS treatment represent significant advances in therapy. The oral route of administration clearly promotes patient satisfaction and increases therapeutic compliance. However, these drugs may also have safety and tolerability issues, and a thorough analysis of the risks and benefits is required. Three oral drugs have been approved by regulatory agencies for MS treatment: fingolimod, teriflunomide, and dimethyl fumarate. This article reviews the mechanisms of action, safety, and efficacy of these drugs and two other drugs that have yielded positive results in phase III trials: cladribine and laquinimod.

Design of oral agents for the management of multiple sclerosis: benefit and risk assessment for dimethyl fumarate

Dimethyl fumarate (DMF) is the most recent oral disease-modifying therapy approved by the US Food and Drug Administration and is indicated for the treatment of relapsing forms of multiple sclerosis (MS). Prior to approval for use in MS, DMF and its active metabolite, monomethyl fumarate, had been used for decades as two of the fumaric acid esters in Fumaderm, a medication used in Europe for the treatment of psoriasis. The unique mechanism of action of DMF remains under evaluation; however, it has been shown to act through multiple pathways leading to shifts away from the Th1 proinflammatory response to the less inflammatory Th2 response. Preliminary data suggest that DMF may induce neuroprotective effects in central nervous system white matter, although further studies are needed to demonstrate these effects on inflammatory demyelination. The DMF Phase III clinical trials demonstrated its efficacy with regard to a reduction in the annualized relapse rate and reductions in new or enlarging T2 lesions and numbers of gadolinium-enhancing lesions on magnetic resonance imaging. DMF has a well-defined safety profile, given the experience with its use in the treatment of psoriasis, and more recently from the DMF clinical trials program and post-marketing era for treatment of MS. The safety profile and oral mode of administration of DMF place it as an attractive first-line therapy option for the treatment of relapsing forms of MS. Long-term observational studies will be needed to determine the effects of DMF on progression of disability in MS.

BG-12 (dimethyl fumarate): a review of mechanism of action, efficacy, and safety

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory disease, affecting more than 2.5 million people worldwide with more 400,000 cases in the United States alone. There has been considerable improvement in the treatment of MS, with the introduction of disease-modifying drugs; however, new oral therapies may provide additional benefit by providing an alternative treatment modality and the potential for improved adherence by avoiding the injection-associated side effects and anxiety encountered with some first-line agents. BG-12 (dimethyl fumarate) is an oral agent approved in the United States for the treatment of relapsing forms of MS.

SCOPE

We review published literature about what is known about the mechanism of action of BG-12, and key efficacy and safety findings from three clinical studies in patients with relapsing-remitting MS (RRMS).

FINDINGS

Data from preclinical studies have demonstrated that BG-12 may promote anti-inflammatory and cytoprotective activities that are mediated, at least in part, by the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) antioxidant response pathway. Studies in animals have shown a protective effect of BG-12 on neuronal, axonal and myelin integrity. Results from a phase 2 study and two randomized double-blind placebo-controlled phase 3 studies, CONFIRM and DEFINE, have shown that BG-12 provides clinical and radiologic efficacy in patients with RRMS. At 2 years, BG-12 240 mg twice and three times daily reduced annualized relapse rate (CONFIRM primary endpoint) by 44% and 51% and the risk of relapse (DEFINE primary endpoint) by 49% and 50%, respectively, compared with placebo (all p < 0.001). BG-12 was generally well tolerated and had an acceptable safety profile, with a similar incidence of adverse events across treatment groups.

CONCLUSIONS

BG-12 may have cytoprotective and anti-inflammatory properties that contribute to its efficacy among patients with RRMS. Findings from phase 2 and 3 studies further support BG-12 as an effective initial therapy. ClinicalTrials.gov ID: NCT00168701; NCT00420212: NCT00451451.

Fumaric acid esters in dermatology

Fumaric acid esters (FAE) are substances of interest in dermatology. FAE exert various activities on cutaneous cells and cytokine networks. So far only a mixture of dimethylfumarate (DMF) and three salts of monoethylfumarate (MEF) have gained approval for the oral treatment of moderate-to-severe plaque-type psoriasis in Germany. DMF seems to be the major active component. There is evidence that FAE are not only effective and safe in psoriasis but granulomatous non-infectious diseases like granuloma annulare, necrobiosis lipoidica and sarcoidosis. In vitro and animal studies suggest some activity in malignant melanoma as well.

Emerging oral drugs for relapsing-remitting multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), traditionally considered to be an autoimmune, demyelinating disease. The last two decades have witnessed the introduction of several therapies for MS. At present, there are five licensed first-line, disease-modifying drugs (DMDs) in MS and two second-line treatments. Nevertheless, in clinical practice DMDs or immunosuppressive treatments are frequently associated with suboptimal response in terms of efficacy and several side effects leading to poor patient adherence.

AREAS COVERED

Since MS is a chronic disease, DMDs require long-term, regular injection or monthly parenteral infusions, which may be uncomfortable and inconvenient for the patient. Thus, there is an important need for new therapeutic strategies, especially those that may offer greater patient satisfaction in order to optimize therapeutic outcomes. Currently, five oral therapies are in Phase III development or have recently been approved for the treatment of relapsing-remitting MS: cladribine and fingolimod, the first approved in Russia and Australia, the latter is more widespread. Fumaric acid (BG-12), teriflunomide (A77126 or HMR1726) and laquinimod (ABR-215062) are in Phase III trials. Details of these five drugs will be covered in this review.

EXPERT OPINION

Preliminary results indicate that oral medications are as effective as, or possibly more effective than, current injectable formulations. It is believable that improved outcomes will translate into higher real and perceived efficacy rates and contribute to improved adherence. The decision to switch established patients from injectable to oral medications will be made on balancing the efficacy and tolerability of the patient's existing therapy and their compliance history, even though safety is likely to become the most important factor in the future development of MS drugs.

Downregulation of endothelial adhesion molecules by dimethylfumarate, but not monomethylfumarate, and impairment of dynamic lymphocyte-endothelial cell interactions

Although fumaric acid esters (FAE) have a decade-long firm place in the therapeutic armamentarium for psoriasis, their pleiotropic mode of action is not yet fully understood. While most previous studies have focused on the effects of FAE on leucocytes, we have addressed their activity on macro- and microvascular endothelial cells. As detected both on mRNA and protein levels, dimethylfumarate effected a profound reduction of TNFα-induced expression of E-selectin (CD62E), ICAM-1 (CD54) and VCAM-1 (CD106) on two different endothelial cell populations in a concentration-dependent manner. This reduction of several endothelial adhesion molecules was accompanied by a dramatic diminution of both rolling and firm adhesive interactions between endothelial cells and lymphocytes in a dynamic flow chamber system. Dimethylfumarate, at a concentration of 50 μm, reduced lymphocyte rolling on endothelial cells by 85.9% (P<0.001 compared to untreated controls), and it diminished the number of adherent cells by 88% (P<0.001). In contrast, monomethylfumarate (MMF) influenced neither surface expression of adhesion molecules nor interactions between endothelial cells and lymphocytes. These observations demonstrate that endothelial cells, in addition to the known effects on leucocytes, undergo profound functional changes in response to dimethylfumarate. These changes are accompanied by severely impaired dynamic interactions with lymphocytes, which constitute the critical initial step of leucocyte recruitment to inflamed tissues in psoriasis and other TNF-related inflammatory disorders.

Development of oral immunomodulatory agents in the management of multiple sclerosis

The emergence of oral disease-modifying therapies in multiple sclerosis (MS) will have a significant impact on the evolving scenario of immunomodulatory treatments in MS where current therapies are all injectable. Reducing relapses in trials translates for individuals with MS into a therapeutic aim of stopping future events. Thus the possible absence of any perceived benefits to the individual together with the long disease course, variable outcome, and a younger age group affected in MS makes side effects the major issue. The use of disease-modifying therapies as a whole needs to be placed in the context of a widening therapeutic indication where the use of these therapies is being justified at an increasingly early stage and in pre-MS syndromes such as clinically isolated and radiologically isolated syndromes where no fixed disability is likely to have accumulated. The five oral therapies discussed (cladribine, fingolimod, laquinimod, BG-12, and teriflunomide) have just completed Phase III studies and some have just been licensed. New oral drugs for MS need to be placed within this evolving marketplace where ease of delivery together with efficacy and side effects needs to be balanced against the known issues but also the known long-term safety of standard injectables.

Dimethylfumarate inhibits angiogenesis in vitro and in vivo: a possible role for its antipsoriatic effect?

The fumaric acid esters (FAEs) have been used for the oral treatment of psoriasis for some 50 years. Given that a persistent and maintained angiogenesis is associated with several cutaneous diseases, including psoriasis, we sought in our study to gain further insight into their mechanism of action by investigating whether FAEs are able to interfere with angiogenesis mechanisms. Our results demonstrate that dimethylfumarate (DMF) inhibits certain functions of endothelial cells, namely, differentiation, proliferation, and migration. This activity was not exhibited by similar concentrations of monomethylfumarate or fumaric acid. Our data indicate that DMF inhibits the growth of transformed and nontransformed cells in a dose-dependent manner. The growth-inhibitory effect exerted by this compound on proliferating endothelial cells could be due, at least in part, to an induction of apoptosis. Inhibition by DMF of the mentioned essential steps of in vitro angiogenesis is consistent with the observed inhibition of in vivo angiogenesis, substantiated using chick chorioallantoic membrane and live fluorescent zebrafish embryo neovascularization assays. The antiangiogenic activity of DMF may contribute to the antipsoriatic, antitumoral, and antimetastatic activities of this compound and suggests its potential in the treatment of angiogenesis-related malignancies.

Combination of dacarbazine and dimethylfumarate efficiently reduces melanoma lymph node metastasis

Dimethylfumarate (DMF) has been shown to reduce melanoma growth and metastasis in animal models. We addressed the question of whether DMF is as effective in its antitumor activity as the US Food and Drug Administration-approved alkylating agent dacarbazine (DTIC). We also tested the possibility of an improved antitumoral effect when both therapeutics were used together. Using our severe combined immunodeficiency (SCID) mouse model, in which xenografted human melanoma cells metastasize from primary skin sites to sentinel nodes, we show that these treatments, alone or in combination, reduce tumor growth at primary sites. Our main finding was that metastasis to sentinel nodes is significantly delayed only in mice treated with a combination of DTIC and DMF. Subsequent experiments were able to show that a combination of DTIC/DMF significantly reduced lymph vessel density in primary tumors as examined by real-time PCR and immunohistochemistry. In addition, DTIC/DMF treatment significantly impaired melanoma cell migration in vitro. In vivo, DTIC/DMF therapy significantly reduced mRNA expression and protein concentration of the promigratory chemokines CXCL2 and CXCL11. In addition, our data suggest that this xenotransplantation model is suitable for preclinical testing of various combinations of antimelanoma agents.

Angiogenesis drives psoriasis pathogenesis

Psoriasis pathogenesis is closely associated with disease-inducing Th1 and Th17 cells. Yet, several studies suggest that aberrant keratinocyte or endothelial cell signalling significantly contributes to disease manifestation. Histological hallmarks of psoriatic skin include the infiltration of multiple immune cells, keratinocyte proliferation and increased dermal vascularity. Formation of new blood vessels starts with early psoriatic changes and disappears with disease clearance. Several angiogenic mediators like vascular endothelial growth factor, hypoxia-inducible factors, angiopoietins and pro-angiogenic cytokines, such as tumour necrosis factor (TNF), interleukin (IL)-8 and IL-17, are up-regulated in psoriasis development. Contact- and mediator-dependent factors derived from keratinocytes, mast cells and immune cells may contribute to the strong blood vessel formation of psoriasis. New technologies and experimental models provide new insights into the role of angiogenesis in psoriasis pathogenesis. Interestingly, many therapies target not only immune cells, but also protein structures of endothelial cells. Here we summarize the role of pro-angiogenic factors in psoriasis development and discuss angiogenesis as a potential target of novel therapies.

The Nrf2-antioxidant response element signaling pathway and its activation by oxidative stress

A major mechanism in the cellular defense against oxidative or electrophilic stress is activation of the Nrf2-antioxidant response element signaling pathway, which controls the expression of genes whose protein products are involved in the detoxication and elimination of reactive oxidants and electrophilic agents through conjugative reactions and by enhancing cellular antioxidant capacity. At the molecular level, however, the regulatory mechanisms involved in mediating Nrf2 activation are not fully understood. It is well established that Nrf2 activity is controlled, in part, by the cytosolic protein Keap1, but the nature of this pathway and the mechanisms by which Keap1 acts to repress Nrf2 activity remain to be fully characterized and are the topics of discussion in this minireview. In addition, a possible role of the Nrf2-antioxidant response element transcriptional pathway in neuroprotection will also be discussed.

Efficacy and safety of oral fumarate in patients with relapsing-remitting multiple sclerosis: a multicentre, randomised, double-blind, placebo-controlled phase IIb study

BACKGROUND

Oral fumarate (BG00012) might have dual anti-inflammatory and neuroprotective effects. Our aim was to assess the efficacy and safety of BG00012 in patients with relapsing-remitting multiple sclerosis.

METHODS

257 patients, aged 18-55 years, with relapsing-remitting multiple sclerosis were randomly assigned to receive 120 mg once daily (n=64), 120 mg three times daily (n=64), or 240 mg three times daily (n=64) BG00012, or placebo (n=65) for 24 weeks. During an extension period of 24 weeks for safety assessment, patients treated with placebo received BG00012 240 mg three times daily. The primary endpoint was total number of new gadolinium enhancing (GdE) lesions on brain MRI scans at weeks 12, 16, 20, and 24. Additional endpoints included cumulative number of new GdE lesions (weeks 4-24), new or enlarging T2-hyperintense lesions, new T1-hypointense lesions at week 24, and annualised relapse rate. Analysis was done on the efficacy-evaluable population. Safety and tolerability were also assessed. This study is registered with ClinicalTrials.gov, number NCT00168701.

FINDINGS

Treatment with BG00012 240 mg three times daily reduced by 69% the mean total number of new GdE lesions from week 12 to 24 compared with placebo (1.4 vs 4.5, p<0.0001). It also reduced number of new or enlarging T2-hyperintense (p=0.0006) and new T1-hypointense (p=0.014) lesions compared with placebo. BG00012 reduced annualised relapse rate by 32% (0.44 vs 0.65 for placebo; p=0.272). Adverse events more common in patients given BG00012 than in those given placebo included abdominal pain, flushing, and hot flush. Dose-related adverse events in patients on BG00012 were headache, fatigue, and feeling hot.

INTERPRETATION

The anti-inflammatory effects and favourable safety profile of BG00012 warrant further long-term phase III studies in large patient groups.

Dimethyl fumarate, a small molecule drug for psoriasis, inhibits Nuclear Factor-kappaB and reduces myocardial infarct size in rats

Persistent Nuclear Factor-kappaB (NF-kappaB) activation is hypothesized to contribute to myocardial injuries following ischemia-reperfusion. Because inhibition or control of NF-kappaB signaling in the heart probably confers cardioprotection, we determined the potency of the NF-kappaB inhibitor dimethyl fumarate (DMF) in cardiovascular cells, and determined whether administration of DMF translates into beneficial effects in an animal model of myocardial infarction. In rat heart endothelial cells (RHEC), we analysed inhibitory effects of DMF on NF-kappaB using shift assay and immunohistofluorescence. In in vivo experiments, male Sprague Dawley rats undergoing left coronary artery occlusion for 45 min received either DMF (10 mg/kg body weight) or vehicle 90 min before ischemia as well as immediately before ischemia. After 120 min of reperfusion, the hearts were stained with phthalocyanine blue dye and triphenyltetrazolium chloride. Additionally, acute hemodynamic and electrophysiologic effects of DMF were determined in dose-response experiments in isolated perfused rat hearts. DMF inhibited TNF-alpha-induced nuclear entry of NF-kappaB in RHEC. In in vivo experiments, myocardial infarct size was significantly smaller in rats that had received DMF (20.7%+/-9.7% in % of risk area; n=17) than in control rats (28.2%+/-6.2%; n=15). Dose-response experiments in isolated perfused rat hearts excluded acute hemodynamic or electrophysiologic effects as mechanisms for the effects of DMF. DMF inhibits nuclear entry of NF-kappaB in RHEC and reduces myocardial infarct size after ischemia and reperfusion in rats in vivo. There was no indication that the beneficial effects of DMF were due to acute hemodynamic or electrophysiologic influences.

Targeting selectins and selectin ligands in inflammation and cancer

Inflammation and cancer metastasis are associated with extravasation of leukocytes or tumor cells from blood into tissue. Such movement is believed to follow a coordinated and sequential molecular cascade initiated, in part, by the three members of the selectin family of carbohydrate-binding proteins: E-selectin (CD62E), L-selectin (CD62L) and P-selectin (CD62P). E-selectin is particularly noteworthy in disease by virtue of its expression on activated endothelium and on bone-skin microvascular linings and for its role in cell rolling, cell signaling and chemotaxis. E-selectin, along with L- or P-selectin, mediates cell tethering and rolling interactions through the recognition of sialo-fucosylated Lewis carbohydrates expressed on structurally diverse protein-lipid ligands on circulating leukocytes or tumor cells. Major advances in understanding the role of E-selectin in inflammation and cancer have been advanced by experiments assaying E-selectin-mediated rolling of leukocytes and tumor cells under hydrodynamic shear flow, by clinical models of E-selectin-dependent inflammation, by mice deficient in E-selectin and by mice deficient in glycosyltransferases that regulate the binding activity of E-selectin ligands. Here, the authors elaborate on how E-selectin and its ligands may facilitate leukocyte or tumor cell recruitment in inflammatory and metastatic settings. Antagonists that target cellular interactions with E-selectin and other members of the selectin family, including neutralizing monoclonal antibodies, competitive ligand inhibitors or metabolic carbohydrate mimetics, exemplify a growing arsenal of potentially effective therapeutics in controlling inflammation and the metastatic behavior of cancer.

Therapeutic potential of selectin antagonists in psoriasis

Psoriasis is a systemic chronic inflammatory disorder. One of the major characteristics is an excess of infiltration of inflammatory cells, mainly lymphocytes, into the skin. Because the adhesion family of selectins is suggested to play a relevant role in this process, selectins have emerged as an interesting target for drug discovery and development in psoriasis. Different strategies targeting selectins have been described. This review discusses these approaches and summarises the current development of selectin antagonists for the treatment of psoriasis. An expert opinion will give the authors' personal opinion about selectin antagonism in psoriasis and which approach might be preferable.

Dimethylfumarate specifically inhibits the mitogen and stress-activated kinases 1 and 2 (MSK1/2): possible role for its anti-psoriatic effect

The p38 mitogen-activated protein kinase (MAPK) signaling pathway, which regulates the activity of different transcriptions factors including NF-kappaB, is activated in lesional psoriatic skin. The purpose of this study was to investigate the effect of fumaric acid esters (FAEs) on the p38 MAPK and the downstream kinases mitogen- and stress-activated protein kinase (MSK)1 and 2 in cultured human keratinocytes. Cell cultures were incubated with dimethylfumarate (DMF), methylhydrogenfumarate (MHF), or fumaric acid (FA) and then stimulated with IL-1beta before kinase activation was determined by Western blotting. A significant inhibition of both MSK1 and 2 activations was seen after preincubation with DMF and stimulation with IL-1beta, whereas MHF and FA had no effect. In addition, DMF decreased phosphorylation of NF-kappaB/p65 (Ser276), which is known to be transactivated by MSK1. Furthermore, incubation with DMF before stimulation with IL-1beta resulted in a significant decrease in NF-kappaB binding to the IL-8 kappaB and the IL-20 kappaB-binding sites as well as a subsequent decrease in IL-8 and IL-20 mRNA expression. Our results suggest that DMF specifically inhibits MSK1 and 2 activations and subsequently inhibits NF-kappaB-induced gene-transcriptions, which are believed to be important in the pathogenesis of psoriasis. These effects of DMF explain the anti-psoriatic effect of FAEs.

Dimethylfumarate inhibits nuclear binding of nuclear factor kappaB but not of nuclear factor of activated T cells and CCAAT/enhancer binding protein beta in activated human T cells

BACKGROUND

Psoriasis is a chronic inflammatory skin disorder in which T-cell-mediated immune responses are thought to play a prominent role. Fumaric acid esters (FAEs) have proved to be an effective systemic treatment for psoriasis. The FAE dimethylfumarate (DMF) strongly suppresses chemokine production in human keratinocytes and peripheral blood mononuclear cells. Additionally, it has been demonstrated that the nuclear translocation of the activated transcription factor nuclear factor kappaB (NF-kappaB) is inhibited in human endothelial cells and fibroblasts activated with tumour necrosis factor-alpha. The NF-kappaB pathway plays a major role in regulating inflammatory cytokine production as well as in cell differentiation and apoptosis. T-cell survival is also dependent on the activation of NF-kappaB and it has been demonstrated in vitro that DMF is an inducer of apoptosis in human T cells. The influence of FAEs on the expression of nuclear transcription factors in T cells has not yet been investigated.

OBJECTIVES

The effects of DMF and its main metabolite, methylhydrogenfumarate (MHF), were assessed on the nuclear binding of NF-kappaB, nuclear factor of activated T cells (NF-AT) and CCAAT/enhancer binding protein beta (C/EBPbeta) in purified human T cells.

METHODS

To examine the effect of DMF and MHF on the nuclear binding of NF-kappaB, NF-AT and C/EBPbeta in human T cells and fibroblasts, an enzyme-linked immunosorbent assay (ELISA) was used. The binding activity of these transcription factors was measured by its absorbance in an ELISA plate reader at 450 nm. Conspicuous results were confirmed by performing electrophoretic mobility shift assays.

RESULTS

DMF inhibited nuclear binding of NF-kappaB1, but not of NF-AT or C/EBPbeta, in purified human T cells. No effect of MHF on any of these transcription factors could be seen. To verify our results, we used the same assay to show the inhibitory effect on the nuclear binding of NF-kappaB1 in human fibroblasts (as previously published).

CONCLUSIONS

The results of this study provide evidence for a specific effect of DMF on NF-kappaB. The data support previous results where NF-kappaB-dependent mediators and surface molecules were suppressed by DMF, but not those activated by other nuclear transcription factors.

Dimethylfumarate impairs melanoma growth and metastasis

Dimethylfumarate (DMF) inhibits signals transmitted by Rel proteins and is used for the treatment of inflammatory skin diseases such as psoriasis, but potential effects of DMF on tumor progression have yet not been analyzed. We show that DMF reduced melanoma growth and metastasis in severe combined immunodeficient mouse models. To identify targets of DMF action, we analyzed mRNA expression in DMF-treated melanomas by gene chip arrays. Using BiblioSphere software for data analysis, significantly regulated genes were mapped to Gene Ontology terms cell death, cell growth, and cell cycle. Indeed, we found that DMF inhibited proliferation of human melanoma cells A375 and M24met in vitro. The cell cycle was arrested at the G(2)-M boundary. Moreover, DMF was proapoptotic, as shown by cell cycle analysis and by Annexin V and Apo2.7 staining. These results were confirmed in vivo. DMF reduced proliferation rates of tumor cells as assessed by Ki-67 immunostaining and increased apoptosis as assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining. In conclusion, DMF is antiproliferative and proapoptotic and reduces melanoma growth and metastasis in animal models.

Dimethylfumarate induces immunosuppression via glutathione depletion and subsequent induction of heme oxygenase 1

A mixture of different fumaric acid esters (FAE) is established for systemic therapy of psoriasis, a frequent inflammatory skin disease. The main active compound of FAE, however, has not been identified so far, and the mechanisms of activity are only partially understood. We analyzed the impact of FAE on in vitro immune function and aimed to gain knowledge about the mode of action. Dimethylfumarate (DMF) and diethylfumarate (DEF), but not fumaric acid, methylhydrogenfumarate and ethylhydrogenfumarate, exhibited potent depression of inflammatory cytokine secretion (e.g., tumor necrosis factoralpha, IL-12, and IFNgamma) in activated human peripheral blood mononuclear cells. Moreover, solely DMF and DEF inhibited alloreactive T-cell proliferation in mixed leukocyte reaction. Interestingly, these immunosuppressive effects were accompanied by the strong induction of the anti-inflammatory stress protein heme oxygenase 1 (HO-1). Supplementation with exogenous glutathione (GSH), which is known to bind DMF, prevented both HO-1 induction as well as the anti-inflammatory effects of DMF. Moreover, inhibition of HO-1 activity restored the diminished IL-12 and IFNgamma production after FAE treatment. These results suggest that DMF acts as active compound within the FAE mixture and at least partially mediates its immunomodulatory activity by the induction of the anti-inflammatory stress protein HO-1 ascribed to the functional depletion of reduced GSH.

Evidence of covalent interaction of fumaric acid esters with sulfhydryl groups in peptides

Fumaric acid esters, namely dimethylfumarate, have been used for the treatment of psoriasis for many years. Still, their mode of action is not fully clear. Because addition of nucleophiles to the double bonds of fumarates can occur (Michael analogous addition), a study of the interaction of fumarates with cysteine and cysteine-containing peptides possessing nucleophilic sulfhydryl group was carried out. Experiments were performed in aqueous medium at pH 7.4 and at 37 degrees C to simulate physiological conditions. It was proven by mass spectrometric measurements using an ion-trap and time-of-flight instrument that a covalent bond can form between fumarates and the sulfhydryl group of cysteine or cysteinyl residues in peptides. Structures of the interaction products were elucidated by multistage mass spectrometry applying collision-induced dissociation. Higher reactivity of dimethylfumarate in comparison to monomethylfumarate and fumaric acid was observed.

Emerging drugs in psoriasis

Psoriasis is a relatively common, chronic skin disease affecting 1-2% of the population in the developed countries. It is an inflammatory, autoimmune skin disorder characterised by an accelerated rate of epidermal proliferation and disordered differentiation. Since our last review in 1999, considerable progress has been made in understanding the immunopathogenesis of this disease, and new drugs have become available for its treatment. Recent clinical trials showed the efficacy of novel biotechnology approaches, such as blocking tumour necrosis factor-alpha or T-cell-mediated immune response by the anti-CD2, anti-CD11a, anti-B7, anti-CD4 or anti-CD25 approaches. Agents which block type 1 cytokines or skew immune reactions into type 2 are other promising approaches. Other possible targets are chemokines and their receptors, the cytokines and receptors involved in T cell trafficking into the skin, and peroxisome proliferator-activated receptors. Relatively little development is reported of the drugs targeting the keratinocyte or the classical antipsoriatic compounds which include glucocorticoids, vitamin D derivatives and cytostatic agents.

Psoriasis: emerging therapeutic strategies

Psoriasis is a chronic inflammatory skin disorder that is characterized by thickened, scaly plaques, and is estimated to affect approximately 1-3% of the Caucasian population. Traditional treatments, although effective in patients with limited disease, have numerous shortcomings, including inconvenience and toxicity. These drawbacks mean that many patients experience cycles of disease clearance, in which normal quality of life alternates with active disease and poor quality of life. However, as this review discusses, recent advances have highlighted the key role of the immune system in the pathogenesis of psoriasis, and have provided new defined targets for therapeutic intervention, offering hope for safe and effective psoriasis treatment.

Fumaric acid esters in the treatment of psoriasis: an Italian experience

BACKGROUND

Psoriasis is a common, chronic, cell-mediated, inflammatory skin disease. Treatment limitations and a developing understanding of its pathogenesis on a molecular level have encouraged much interest in the field of immunomodulatory therapy.

OBJECTIVE

To evaluate the efficacy and safety of fumaric acid esters, in particular dimethylfumarate (DMF), in the treatment of moderate to severe plaque psoriasis intolerant and/or resistant to other conventional systemic therapies.

METHODS

A total of 40 patients were enrolled in this study. DMF was orally administered at the daily dose of 30 mg up to 360 mg for a minimum of 6 months treatment. Patients were followed-up with psoriasis area and severity index (PASI) score assessment, and clinical and photographic documentation.

RESULTS

A total of 33 (82.5%) patients achieved complete clinical remission with DMF treatment: eight after 3 months and 25 after 6 months. Adverse events, such as intolerable abdominal cramps and incoercible diarrhoea, occurred in four patients who, for this reason, interrupted therapy.

CONCLUSION

The findings suggest that DMF is a safe, effective and well-tolerated long-term oral treatment worthy of consideration for selective patients.

Dimethylfumarate is a potent inducer of apoptosis in human T cells

Fumaric acid esters (FAE) have been used for the systemic treatment of psoriasis in Germany for almost 50 years. Recently, it has been shown that dimethylfumarate (DMF) as the main ingredient of the marketed FAE mixture is a potent inhibitor of the nuclear transcription factor NF-kappaB. DMF was also shown to induce apoptosis in various cells. Because T cells play a crucial role in psoriasis pathogenesis, we asked whether DMF and its main metabolite methylhydrogenfumarate (MHF) were able to induce apoptosis in these cells. Purified human T cells were treated with DMF and MHF (1-20 microg/mL) and stimulated with interleukin 2, anti-CD3 antibodies or both for 48 h, and apoptosis was subsequently determined by the expression of Apo2.7 as well as by terminal deoxynucleotide transferase nick end labeling. The expression of antiapoptotic protein Bcl-2 was simultaneously determined. The results showed a dose-and-time dependent up-regulation of Apo2.7 expression and DNA fragmentation by DMF preferable in stimulated T cells. MHF and the solvent dimethyl sulfoxide were without effect. DMF, but not MHF, led to a concentration-dependent decrease of Bcl-2 expression in interleukin-2-stimulated T cells. The data provide evidence that the effect of FAE treatment of psoriasis may at least in part be due to induction of apoptosis in activated T cells.