Amelioration of ongoing experimental autoimmune encephalomyelitis with fluoxetine

Fluoxetine restrains allergic inflammation by targeting an FcɛRI-ATP positive feedback loop in mast cells

There is a clinical need for new treatment options addressing allergic disease. Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that have anti-inflammatory properties. We tested the effects of the SSRI fluoxetine on IgE-induced function of mast cells, which are critical effectors of allergic inflammation. We showed that fluoxetine treatment of murine or human mast cells reduced IgE-mediated degranulation, cytokine production, and inflammatory lipid secretion, as well as signaling mediated by the mast cell activator ATP. In a mouse model of systemic anaphylaxis, fluoxetine reduced hypothermia and cytokine production. Fluoxetine was also effective in a model of allergic airway inflammation, where it reduced bronchial responsiveness and inflammation. These data show that fluoxetine suppresses mast cell activation by impeding an FcɛRI-ATP positive feedback loop and support the potential repurposing of this SSRI for use in allergic disease.

Autophagic Molecular Alterations in the Mouse Cerebellum Experimental Autoimmune Encephalomyelitis Model Following Treatment with Cannabidiol and Fluoxetine

The crosstalk between autophagy and apoptosis is one of the most important processes involved in the cell program death, and several mechanisms including oligodendrocyte apoptosis and autophagy play significant roles in activating macrophages, microglial cells, and finally demyelination in neurodegenerative disease. The antidepressants and anti-apoptotic mechanisms of fluoxetine (FLX) and cannabidiol (CBD) commence an autophagic event that can effectively repair myelin. This study aimed to investigate the effect of those reagents on the rate of demyelination in the cerebellum, an important site for white matter in a mouse model of experimental autoimmune encephalomyelitis (EAE). EAE was induced in twenty four adult female C57Bl/6 mice were inducted the EAE model; FLX treatment which was performed (10 mg/kg/IP) and CBD; were treated (5 mg/kg/IP); and their cerebellum was used for Western blotting, real-time PCR to autophagic markers of LC3II, Beclin-1, and apoptotic markers Bax and Bcl2 evaluation and Luxol Fast Blue staining to the assessment of demyelination. The level of autophagic markers was expressively elevated (P < 0.01) but the pro-apoptotic markers and Bax/Bcl2 ratio were reduced (P < 0.05). Luxol Fast Blue staining confirmed the noteworthy diminution of demyelination in treatment groups (P < 0.001). This finding clarified that FLX and CBD ameliorate the severity of the EAE model. Combinatory treatments of these two agents are suggested for future investigations.

Immunostimulatory activity of fluoxetine in macrophages via regulation of the PI3K and P38 signaling pathways

Fluoxetine is an antidepressant drug that is heavily preferred in the cure of depression, which is from the selective serotonin reuptake inhibitor (SSRI) group. There are many reports on the effect of fluoxetine on the immune system, and its effect on the macrophage cells has never been looked at before. We aimed to demonstrate the cytokine production potential of fluoxetine antidepressant, which is widely used in the clinic, in the J774.2 cell line and its effect on PI3K and P38 pathways. The use of fluoxetine alone in J774.2 macrophage cells showed immunostimulatory properties by inducing the production of tumor necrosis factor-α (TNF-α), interleukin (IL) IL-6, IL-12p40, and granulocyte–macrophage colony-stimulating factor (GM-CSF) cytokines. It showed anti-inflammatory properties by completely stopping the production of cytokines (IL-6, IL12p40, TNF-α, and GM-CSF) at all concentrations where LPS and fluoxetine were used together. While PI3K and P38 pathways were not effective in the immunostimulatory effect in the presence of the drug agent, we found that the PI3K and P38 pathways were influenced during their anti-inflammatory activity.

Lactobacillus reuteri tryptophan metabolism promotes host susceptibility to CNS autoimmunity

BACKGROUND

Dysregulation of gut microbiota-associated tryptophan metabolism has been observed in patients with multiple sclerosis. However, defining direct mechanistic links between this apparent metabolic rewiring and individual constituents of the gut microbiota remains challenging. We and others have previously shown that colonization with the gut commensal and putative probiotic species, Lactobacillus reuteri, unexpectedly enhances host susceptibility to experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. To identify underlying mechanisms, we characterized the genome of commensal L. reuteri isolates, coupled with in vitro and in vivo metabolomic profiling, modulation of dietary substrates, and gut microbiota manipulation.

RESULTS

The enzymes necessary to metabolize dietary tryptophan into immunomodulatory indole derivatives were enriched in the L. reuteri genomes, including araT, fldH, and amiE. Moreover, metabolite profiling of L. reuteri monocultures and serum of L. reuteri-colonized mice revealed a depletion of kynurenines and production of a wide array of known and novel tryptophan-derived aryl hydrocarbon receptor (AhR) agonists and antagonists, including indole acetate, indole-3-glyoxylic acid, tryptamine, p-cresol, and diverse imidazole derivatives. Functionally, dietary tryptophan was required for L. reuteri-dependent EAE exacerbation, while depletion of dietary tryptophan suppressed disease activity and inflammatory T cell responses in the CNS. Mechanistically, L. reuteri tryptophan-derived metabolites activated the AhR and enhanced T cell production of IL-17.

CONCLUSIONS

Our data suggests that tryptophan metabolism by gut commensals, such as the putative probiotic species L. reuteri, can unexpectedly enhance autoimmunity, inducing broad shifts in the metabolome and immunological repertoire. Video Abstract.

T Lymphocyte Serotonin 5-HT7 Receptor Is Dysregulated in Natalizumab-Treated Multiple Sclerosis Patients

Serotonin (5-HT) is known as a potent immune cell modulator in autoimmune diseases and should be protective in the pathogenesis of multiple sclerosis (MS). Nevertheless, there is limited knowledge about receptors involved in 5-HT effects as well as induced mechanisms. Among 5-HT receptors, the 5-HT₇ receptor is able to activate naïve T cells and influence the inflammatory response; however, its involvement in the disease has never been studied so far. In this study, we collected blood sample from three groups: acute relapsing MS patients (ARMS), natalizumab-treated MS patients (NTZ), and control subjects. We investigated the 5-HT₇ expression on circulating lymphocytes and evaluated the effects of its activation on cytokine production with peripheral blood mononuclear cell (PBMC) cultures. We found a significant increase in the 5-HT₇ surface expression on T lymphocytes and on the different CD4⁺ T cell subsets exclusively in NTZ-treated patients. We also showed that the selective agonist 5-carboxamidotryptamine (5-CT)-induced 5-HT₇R activation significantly promotes the production of IL-10, a potent immunosuppressive cytokine in PBMCs. This study provides for the first time a dysregulation of 5-HT₇ expression in NTZ-MS patients and its ability to promote IL-10 release, suggesting its protective role. These findings strengthen the evidence that 5-HT₇ may play a role in the immuno-protective mechanisms of NTZ in MS disease and could be considered as an interesting therapeutic target in MS.

Serotonergic drug repurposing in multiple sclerosis: A new possibility for disease-modifying therapy

Investigation of neuroimmune interactions is one of the most developing areas in the study of multiple sclerosis pathogenesis. Recent evidence suggests the possibility of modulating neuroinflammation by targeting biogenic amine receptors. It has been shown that selective serotonin reuptake inhibitor fluoxetine modulates innate and adaptive immune system cells' function and can reduce experimental autoimmune encephalomyelitis and multiple sclerosis severity. This brief report discusses the immune mechanisms underlying the multiple sclerosis pathogenesis and the influence of fluoxetine on them. The retrospective data on the impact of fluoxetine treatment on the course of multiple sclerosis are also presented. The results of this and other studies suggest that fluoxetine could be considered an additional therapy to the standard first-line disease-modifying treatment for relapsing–remitting multiple sclerosis.

Novel Drugs in a Pipeline for Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a widely known inflammatory, demyelinating disease of the central nervous system. The pathogenesis of progressive multiple sclerosis (PMS) is a complex, multi-level process that causes therapeutic difficulties. Along with variables such as age and duration of the disease, pathogenetic mechanisms change from inflammatory to neurodegenerative processes. Therefore, the efficacy of available anti-inflammatory drugs approved for the treatment of PMS, such as ocrelizumab or siponimod, is limited in time. In search of innovative solutions, several research studies have been conducted to evaluate the effectiveness of drugs with neuroprotective or remyelinating effects in PMS, including biotin, ibudilast, simvastatin, alpha-lipoic acid, clemastine, amiloride, fluoxetine, riluzole, masitinib, opicinumab, and lamotrigine. The current review includes those compounds, which have entered the clinical phase of assessment, and the authors discuss future prospects for successful PMS treatment.

SSRIs: Applications in inflammatory lung disease and implications for COVID-19

Selective serotonin reuptake inhibitors (SSRIs) have anti-inflammatory properties that may have clinical utility in treating severe pulmonary manifestations of COVID-19. SSRIs exert anti-inflammatory effects at three mechanistic levels: (a) inhibition of proinflammatory transcription factor activity, including NF-κB and STAT3; (b) downregulation of lung tissue damage and proinflammatory cell recruitment via inhibition of cytokines, including IL-6, IL-8, TNF-α, and IL-1β; and (c) direct suppression inflammatory cells, including T cells, macrophages, and platelets. These pathways are implicated in the pathogenesis of COVID-19. In this review, we will compare the pathogenesis of lung inflammation in pulmonary diseases including COVID-19, ARDS, and chronic obstructive pulmonary disease (COPD), describe the anti-inflammatory properties of SSRIs, and discuss the applications of SSRIS in treating COVID-19-associated inflammatory lung disease.

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

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

Antidepressants on Multiple Sclerosis: A Review of In Vitro and In Vivo Models

Background

Increased prevalence of depression has been observed among patients with multiple sclerosis (MS) and correlated with the elevated levels of proinflammatory cytokines and the overall deregulation of monoaminergic neurotransmitters that these patients exhibit. Antidepressants have proved effective not only in treating depression comorbid to MS, but also in alleviating numerous MS symptoms and even minimizing stress-related relapses. Therefore, these agents could prospectively prove beneficial as a complementary MS therapy.

Objective

This review aims at illustrating the underlying mechanisms involved in the beneficial clinical effects of antidepressants observed in MS patients.

Methods

Through a literature search we screened and comparatively assessed papers on the effects of antidepressant use both in vitro and in vivo MS models, taking into account a number of inclusion and exclusion criteria.

Results

In vitro studies indicated that antidepressants promote neural and glial cell viability and differentiation, reduce proinflammatory cytokines and exert neuroprotective activity by eliminating axonal loss. In vivo studies confirmed that antidepressants delayed disease onset and alleviated symptoms in Experimental Autoimmune Encephalomyelitis (EAE), the most prevalent animal model of MS. Further, antidepressant agents suppressed inflammation and restrained demyelination by decreasing immune cell infiltration of the CNS.

Conclusion

Antidepressants were efficient in tackling numerous aspects of disease pathophysiology both in vitro and in vivo models. Given that several antidepressants have already proved effective in clinical trials on MS patients, the inclusion of such agents in the therapeutic arsenal of MS should be seriously considered, following an individualized approach to minimize the adverse events of antidepressants in MS patients.

The role of 5-HT2B-receptors in fluoxetine-mediated modulation of Th17- and Th1-cells in multiple sclerosis

Fluoxetine is a selective serotonin reuptake inhibitor, which also has an immunomodulatory effect. We investigated the effects of fluoxetine and serotonin (5-HT) on the pro-inflammatory Th17- and Th1-cells in 30 patients with relapsing-remitting MS and 20 healthy subjects. Fluoxetine and 5-HT suppressed IL-17, IFN-γ and GM-CSF production by stimulated СD4⁺ T-cells in both groups. Blockade of 5-HT_2B-receptors decreased the inhibitory effect of fluoxetine on cytokine production in MS patients. Finally, 5-HT_2B-receptor activation inhibits IL-17, IFN-γ and GM-CSF production in both groups. These data suggest an anti-inflammatory role for fluoxetine in MS, which could be mediated by the activation of 5-HT_2B-receptors.

Hormones in experimental autoimmune encephalomyelitis (EAE) animal models

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) in which activated immune cells attack the CNS and cause inflammation and demyelination. While the etiology of MS is still largely unknown, the interaction between hormones and the immune system plays a role in disease progression, but the mechanisms by which this occurs are incompletely understood. Several in vitro and in vivo experimental, but also clinical studies, have addressed the possible role of the endocrine system in susceptibility and severity of autoimmune diseases. Although there are several demyelinating models, experimental autoimmune encephalomyelitis (EAE) is the oldest and most commonly used model for MS in laboratory animals which enables researchers to translate their findings from EAE into human. Evidences imply that there is great heterogeneity in the susceptibility to the induction, the method of induction, and the response to various immunological or pharmacological interventions, which led to conflicting results on the role of specific hormones in the EAE model. In this review, we address the role of endocrine system in EAE model to provide a comprehensive view and a better understanding of the interactions between the endocrine and the immune systems in various models of EAE, to open up a ground for further detailed studies in this field by considering and comparing the results and models used in previous studies.

Serotoninergic system targeting in multiple sclerosis: the prospective for pathogenetic therapy

Serotonin (5-hydroxytryptamine) (5-HT) is a neurotransmitter, which mediates neuropsychological functions of the central nervous system (CNS). Recent studies have shown the modulatory effect of 5-HT on gut microbiota functions, which play an essential role in developing CNS inflammatory diseases. Finally, 5-HT is a direct mediator of neuroimmune interaction. The article reviews the literature data on the role of 5-HT in the regulation of neuroinflammation in multiple sclerosis (MS). The influence of 5-HT and selective serotonin reuptake inhibitors (SSRIs) on experimental autoimmune encephalomyelitis (EAE) and MS pathogenesis, as well as the therapeutic potential of serotoninergic drugs as a pathogenetic therapy of MS, are discussed.

Localisation of clozapine during experimental autoimmune encephalomyelitis and its impact on dopamine and its receptors

Multiple sclerosis is a disease characterised by axonal demyelination in the central nervous system (CNS). The atypical antipsychotic drug clozapine attenuates experimental autoimmune encephalomyelitis (EAE), a mouse model used to study multiple sclerosis, but the precise mechanism is unknown and could include both peripheral and CNS-mediated effects. To better understand where clozapine exerts its protective effects, we investigated the tissue distribution and localisation of clozapine using matrix-assisted laser desorption ionization imaging mass spectrometry and liquid chromatography-mass spectrometry. We found that clozapine was detectable in the brain and enriched in specific brain regions (cortex, thalamus and olfactory bulb), but the distribution was not altered by EAE. Furthermore, although not altered in other organs, clozapine levels were significantly elevated in serum during EAE. Because clozapine antagonises dopamine receptors, we analysed dopamine levels in serum and brain as well as dopamine receptor expression on brain-resident and infiltrating immune cells. While neither clozapine nor EAE significantly affected dopamine levels, we observed a significant downregulation of dopamine receptors 1 and 5 and up-regulation of dopamine receptor 2 on microglia and CD4+-infiltrating T cells during EAE. Together these findings provide insight into how neuroinflammation, as modelled by EAE, alters the distribution and downstream effects of clozapine.

Effects of endocrine disrupting chemicals on myelin development and diseases

In the central and peripheral nervous systems, myelin is essential for efficient conduction of action potentials. During development, oligodendrocytes and Schwann cells differentiate and ensure axon myelination, and disruption of these processes can contribute to neurodevelopmental disorders. In adults, demyelination can lead to important disabilities, and recovery capacities by remyelination often decrease with disease progression. Among environmental chemical pollutants, endocrine disrupting chemicals (EDCs) are of major concern for human health and are notably suspected to participate in neurodevelopmental and neurodegenerative diseases. In this review, we have combined the current knowledge on EDCs impacts on myelin including several persistent organic pollutants, bisphenol A, triclosan, heavy metals, pesticides, and nicotine. Besides, we presented several other endocrine modulators, including pharmaceuticals and the phytoestrogen genistein, some of which are candidates for treating demyelinating conditions but could also be deleterious as contaminants. The direct impacts of EDCs on myelinating cells were considered as well as their indirect consequences on myelin, particularly on immune mechanisms associated with demyelinating conditions. More studies are needed to describe the effects of these compounds and to further understand the underlying mechanisms in relation to the potential for endocrine disruption.

Multiple Sclerosis and Serotonin: Potential Therapeutic Applications

Multiple sclerosis (MS) is a neurodegenerative disease with a complex autoimmune component, and it has a high prevalence among middle-aged females. The manifestations of the disease range from episodic somatosensory dysfunction to progressive and permanent central nervous system (CNS) damage. Due to a high prevalence of psychiatric comorbidities and proven abnormalities in serotonin (5-HT) levels among MS patients, they are usually on drugs that modify the serotonergic system. Through a comprehensive literature review of studies published in the last 10 years related to 5-HT in MS and its therapeutic applications, we aimed to elucidate the mechanism behind the neurotransmitter (NT) levels’ abnormalities. Most importantly, we endeavored to gather the most up-to-date information about the full therapeutic potential of agents acting on this system. We discovered that multiple processes cause low levels of 5-HT in MS patients. The varying levels of the availability of the 5-HT transporter (SERT) in the CNS decreasing overall tryptophan (TRP) levels, and diversion of the amino acid away from its synthetic pathway constitute some of those. Studies in animals have shown that 5-HT levels’ elevations could cause immune-modulating effects and could probably slow down the disease progression rate. Human studies have shown a more diverse and complex response. Promising results have been obtained in the last 10 years regarding 5-HT’s immune-modulatory role in MS patients and its therapeutic applications. Human studies with a larger population and feasible designs are still needed to fully ascertain the effects of serotonin on the immune system and disease progression in patients with MS.

Inflammation-Associated Synaptic Alterations as Shared Threads in Depression and Multiple Sclerosis

In the past years, several theories have been advanced to explain the pathogenesis of Major Depressive Disorder (MDD), a neuropsychiatric disease that causes disability in general population. Several theories have been proposed to define the MDD pathophysiology such as the classic "monoamine-theory" or the "glutamate hypothesis." All these theories have been recently integrated by evidence highlighting inflammation as a pivotal player in developing depressive symptoms. Proinflammatory cytokines have been indeed claimed to contribute to stress-induced mood disturbances and to major depression, indicating a widespread role of classical mediators of inflammation in emotional control. Moreover, during systemic inflammatory diseases, peripherally released cytokines circulate in the blood, reach the brain and cause anxiety, anhedonia, social withdrawal, fatigue, and sleep disturbances. Accordingly, chronic inflammatory disorders, such as the inflammatory autoimmune disease multiple sclerosis (MS), have been associated to higher risk of MDD, in comparison with overall population. Importantly, in both MS patients and in its experimental mouse model, Experimental Autoimmune Encephalomyelitis (EAE), the notion that depressive symptoms are reactive epiphenomenon to the MS pathology has been recently challenged by the evidence of their early manifestation, even before the onset of the disease. Furthermore, in association to such mood disturbance, inflammatory-dependent synaptic dysfunctions in several areas of MS/EAE brain have been observed independently of brain lesions and demyelination. This evidence suggests that a fine interplay between the immune and nervous systems can have a huge impact on several neurological functions, including depressive symptoms, in different pathological conditions. The aim of the present review is to shed light on common traits between MDD and MS, by looking at inflammatory-dependent synaptic alterations associated with depression in both diseases.

Neuroprotective Benefits of Antidepressants in Multiple Sclerosis: Are We Missing the Mark?

The potential of antidepressant medication to have a neuroprotective effect for people with multiple sclerosis (MS) has received increased interest in recent years. The possibility of antidepressants, particularly fluoxetine, for potential repurposing to treat primary progressive and secondary progressive MS is of interest as a result of the relative lack of disease-modifying medications for these subtypes. A number of animal studies have found positive results for a neuroprotective effect of antidepressant use in MS, with human studies showing mixed results. These human studies all have a significant limitation: they exclude people with moderate to severe depressive symptoms, a core symptom of MS beyond that of reactive depression. It is likely that reregulation of the common mechanisms in depression and MS, such as inflammation, serotonin, norepinephrine, glutamate and brain-derived neurotropic factor disruption, and hypothalamic-pituitary-thalamic axis dysregulation, are important to the neuroprotective value of antidepressant medication. Given that MS is known for its heterogeneity, the question might be less about whether antidepressant medication provides neuroprotective benefits to people with multiple sclerosis but for whom they provide benefits and whether we are designing studies that will detect a benefit. To answer these questions, studies must include people with MS and depressive symptoms as well as people with relapsing remitting and chronic subtypes.

Clomipramine, a tricyclic antidepressant, and selegiline, a monoamine oxidase-B inhibitor, modulate the activity of phagocytic cells after oral administration in mice

OBJECTIVES

Our aim was to find out whether clomipramine, a tricyclic antidepressant, and selegiline, a monoamine oxidase-B inhibitor, influence the activity of phagocytic cells after in-vivo administration in mice.

METHODS

Clomipramine and selegiline were administered to Balb/c mice orally at a dose of 1 mg/kg, 7 or 14 times. IL-1β and nitric oxide (NO) levels were measured in supernatants of the peritoneal macrophage cultures stimulated in vitro with lipopolysaccharide from Escherichia coli. The phagocytic activity of the granulocytes and monocytes was determined using a commercial Phagotest 24 and 72 h after the last dose of the investigated drugs.

KEY FINDINGS

Seven doses of clomipramine or selegiline decreased IL-1β production, while a rise in its synthesis was observed after 14 doses of selegiline. Clomipramine administered 14 times increased NO production. Clomipramine and selegiline administered seven times reduced the percentage of phagocytosing granulocytes. The drugs administered 14 times increased the percentage of phagocytosing granulocytes and decreased the percentage of phagocytosing monocytes.

CONCLUSIONS

Both clomipramine and selegiline administered in vivo changed the phagocytic activity of blood cells and IL-1β and NO production by murine peritoneal macrophages. This effect depended on the drug, the number of doses and the type of phagocytic cells.

Modulation of Cytokine-Induced Astrocytic Endothelin-1 Production as a Possible New Approach to the Treatment of Multiple Sclerosis

Background: In the human central nervous system (CN), resting astrocytes do not visually show endothelin-1 (ET-1)-like immunoreactivity. In patients with multiple sclerosis (MS), an inflammatory disorder of the CNS, high levels of ET-1 are found in reactive astrocytes in demyelinated plaques. ET-1 may contribute to the pathology of MS by interrupting the blood-brain-barrier, enhancing inflammatory responses, excitotoxicity and reducing cerebral blood flow.

Methods: We used the human astrocytoma cell line 1321N1 to investigate the role of inflammatory cytokines involved in MS lesions (IL-1β, TNF-α, IFN-γ, LPS, IL-10, TGF-β) on astrocytic ET-1 upregulation. Prucalopride, rolipram, fenofibrate, fluoxetine, simvastatin, daglutril, and resveratrol were investigated as potential candidate drugs to suppress cytokine-induced astrocytic ET-1 production. Effects on ET-1 production were measured using both ELISA and RT-qPCR.

Results and Conclusions: ET-1 secretion by astrocytoma cells was only stimulated by the pro-inflammatory cytokines IL-1β and TNF-α. Fluoxetine, simvastatin, and resveratrol significantly inhibited this IL-1β- and TNF-α-induced ET-1 production. Simvastatin and resveratrol significantly reduced ET-1 mRNA levels, indicating an effect at the level of transcription. Fluoxetine significantly reduced endothelin converting enzyme-1 mRNA levels, suggesting and effect at the level of protein-processing. The required concentrations of simvastatin (>0.1 µM) and resveratrol (>10 µM) cannot be achieved in humans using pharmacologically accepted doses. Fluoxetine exerted a significant inhibitory effect on ET-1 secretion at a concentration of 5 µM, which is pharmacologically achievable in human brain, but the effect was modest (<50% suppression) and probably not sufficient to obtain a clinically relevant ET-1 effect. Our in vitro model can be a useful screening tool in the development of new drugs to suppress astrocytic ET-1 production. The effect of simvastatin was for the most part mediated via the mevalonate pathway, suggesting that this might be an interesting target for further drug development.

Fluoxetine in progressive multiple sclerosis: The FLUOX-PMS trial

Background:

Preclinical studies suggest that fluoxetine has neuroprotective properties that might reduce axonal degeneration in multiple sclerosis (MS).

Objective:

To determine whether fluoxetine slows accumulation of disability in progressive MS.

Methods:

In a double-blind multicenter phase 2 trial, patients with primary or secondary progressive MS were randomized to fluoxetine 40 mg/day or placebo for a period of 108 weeks. Clinical assessments were performed every 12 weeks by trained study nurses who visited the patients at their home. The primary outcome was the time to a 12-week confirmed 20% increase in the Timed 25 Foot Walk or 9-Hole Peg test. Secondary outcomes included the Hauser ambulation index, cognitive tests, fatigue, and brain magnetic resonance imaging (MRI).

Results:

In the efficacy analysis, 69 patients received fluoxetine and 68 patients received placebo. Using the log-rank test ( p = 0.258) and Cox regression analysis ( p = 0.253), we found no significant difference in the primary outcome between the two groups. Due to an unexpected slow rate of progression in the placebo group, there was insufficient statistical power to detect a potential benefit of fluoxetine. We found no differences between the two groups for secondary outcomes.

Conclusion:

The trial failed to demonstrate a neuroprotective effect of fluoxetine in patients with progressive MS.

Interaction of neurotransmitters and neurochemicals with lymphocytes

Neurotransmitters and neurochemicals can act on lymphocytes by binding to receptors expressed by lymphocytes. This review describes lymphocyte expression of receptors for a selection of neurotransmitters and neurochemicals, the anatomical locations where lymphocytes can interact with neurotransmitters, and the effects of the neurotransmitters on lymphocyte function. Implications for health and disease are also discussed.

Silent Free Fall at Disease Onset: A Perspective on Therapeutics for Progressive Multiple Sclerosis

Central nervous system (CNS) degeneration occurs during multiple sclerosis (MS) following several years of reversible autoimmune demyelination. Progressive CNS degeneration appears later during the course of relapsing-remitting MS (RRMS), although it starts insidiously at disease onset. We propose that there is an early subclinical phase also for primary-progressive (PP) MS. Consensus exists that many different cell types are involved during disease onset. Furthermore, the response to the initial damage, which is specific for each individual, would result in distinct pathological pathways that add complexity to the disease and the mechanisms underlying progressive CNS degeneration. Progressive MS is classified as either active or not active, as well as with or without progression. Different forms of progressive MS might reflect distinct or overlapping pathogenetic pathways. Disease mechanisms should be determined for each patient at diagnosis and the time of treatment. Until individualized and time-sensitive treatments that specifically target the molecular mechanisms of the progressive aspect of the disease are identified, combined therapies directed at anti-inflammation, regeneration, and neuroprotection are the most effective for preventing MS progression. This review presents selected therapeutics in support of the overall idea of a multidimensional therapy applied early in the disease. This approach could limit damage and increase CNS repair. By targeting several cellular populations (i.e., microglia, astrocytes, neurons, oligodendrocytes, and lymphocytes) and multiple pathological processes (e.g., inflammation, demyelination, synaptopathy, and excitatory/inhibitory imbalance) progressive MS could be attenuated. Early timing for such multidimensional therapy is proposed as the prerequisite for effectively halting progressive MS.