Lymphocytes In Multiple Sclerosis Research Articles

Ozanimod-mediated remission in experimental autoimmune encephalomyelitis is associated with enhanced activity of CNS CD27low/- NK cell subset.

Ozanimod (RPC1063) is an immunomodulator that has been recently approved by the FDA (2020) for the treatment of relapsing-remitting multiple sclerosis (RRMS). It is a selective agonist of the sphingosine-1-phophate receptors 1 and 5, expressed on naïve and central memory T and B cells, as well as natural killer (NK) cells, and is involved in lymphocyte trafficking. Oral administration of ozanimod was reported to result in rapid and reversible reduction in circulating lymphocytes in multiple sclerosis (MS) patients, however, only minimal effect on NK cells was observed. In this study, we sought to investigate the effect of ozanimod on NK cells and assess whether they play any role in ozanimod-induced remission in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. Active EAE induction was done in C57BL/6 female mice, followed by daily oral treatment with ozanimod (0.6mg/kg) starting at disease onset (score 1). Flow cytometry of blood and CNS was performed 24 hours after the last oral dose of ozanimod treatment in diseased mice. Histological analysis of lumbar spinal cord was performed for evaluating the level of inflammation and demyelination. Depletion of peripheral NK cells was done using anti-NK1.1 mouse antibody (mAb) at day 5 post-EAE induction. Ozanimod was effective in reducing the clinical severity of EAE and reducing the percentage of autoreactive CD4+ and CD8+ T cells along with significant inhibition of lymphocyte infiltration into the spinal cord, accompanied by reversed demyelination. Furthermore, ozanimod treatment resulted in a significant increase in the frequency of total NK cells in the blood and CNS along with upregulation of the activating receptor NKG2D on CD27low/- NK cell subset in the CNS. The effectiveness of ozanimod treatment in inhibiting the progression of the disease was reduced when NK cells were depleted using anti-NK1.1 mAb. The current study demonstrated that ozanimod treatment significantly improved clinical symptoms in EAE mice. Ozanimod and anti-NK1.1 mAb appear to function in opposition to one another. Collectively, our data suggest that ozanimod-mediated remission is associated with an increased percentage of total NK cells and CD27low/- NK cells expressing the activating receptor, NKG2D in the CNS.

Alterations in Lymphocytic Metabolism-An Emerging Hallmark of MS Pathophysiology?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterised by acute inflammation and subsequent neuro-axonal degeneration resulting in progressive neurological impairment. Aberrant immune system activation in the periphery and subsequent lymphocyte migration to the CNS contribute to the pathophysiology. Recent research has identified metabolic dysfunction as an additional feature of MS. It is already well known that energy deficiency in neurons caused by impaired mitochondrial oxidative phosphorylation results in ionic imbalances that trigger degenerative pathways contributing to white and grey matter atrophy. However, metabolic dysfunction in MS appears to be more widespread than the CNS. This review focuses on recent research assessing the metabolism and mitochondrial function in peripheral immune cells of MS patients and lymphocytes isolated from murine models of MS. Emerging evidence suggests that pharmacological modulation of lymphocytic metabolism may regulate their subtype differentiation and rebalance pro- and anti-inflammatory functions. As such, further understanding of MS immunometabolism may aid the identification of novel treatments to specifically target proinflammatory immune responses.

Autoreactive lymphocytes in multiple sclerosis: Pathogenesis and treatment target.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterized by destruction of the myelin sheath structure. The loss of myelin leads to damage of a neuron’s axon and cell body, which is identified as brain lesions on magnetic resonance image (MRI). The pathogenesis of MS remains largely unknown. However, immune mechanisms, especially those linked to the aberrant lymphocyte activity, are mainly responsible for neuronal damage. Th1 and Th17 populations of lymphocytes were primarily associated with MS pathogenesis. These lymphocytes are essential for differentiation of encephalitogenic CD8+ T cell and Th17 lymphocyte crossing the blood brain barrier and targeting myelin sheath in the CNS. B-lymphocytes could also contribute to MS pathogenesis by producing anti-myelin basic protein antibodies. In later studies, aberrant function of Treg and Th9 cells was identified as contributing to MS. This review summarizes the aberrant function and count of lymphocyte, and the contributions of these cell to the mechanisms of MS. Additionally, we have outlined the novel MS therapeutics aimed to amend the aberrant function or counts of these lymphocytes.

Mitochondria, Oxidative Stress, cAMP Signalling and Apoptosis: A Crossroads in Lymphocytes of Multiple Sclerosis, a Possible Role of Nutraceutics.

Multiple sclerosis (MS) is a complex inflammatory and neurodegenerative chronic disease that involves the immune and central nervous systems (CNS). The pathogenesis involves the loss of blood–brain barrier integrity, resulting in the invasion of lymphocytes into the CNS with consequent tissue damage. The MS etiology is probably a combination of immunological, genetic, and environmental factors. It has been proposed that T lymphocytes have a main role in the onset and propagation of MS, leading to the inflammation of white matter and myelin sheath destruction. Cyclic AMP (cAMP), mitochondrial dysfunction, and oxidative stress exert a role in the alteration of T lymphocytes homeostasis and are involved in the apoptosis resistance of immune cells with the consequent development of autoimmune diseases. The defective apoptosis of autoreactive lymphocytes in patients with MS, allows these cells to perpetuate, within the CNS, a continuous cycle of inflammation. In this review, we discuss the involvement in MS of cAMP pathway, mitochondria, reactive oxygen species (ROS), apoptosis, and their interaction in the alteration of T lymphocytes homeostasis. In addition, we discuss a series of nutraceutical compounds that could influence these aspects.

Unraveling B lymphocytes in CNS inflammatory diseases: Distinct mechanisms and treatment targets.

Specific therapies targeting B lymphocytes in multiple sclerosis (MS) have demonstrated reductions in disease activity and disability progression. Several observational studies have also shown the effects of targeting B lymphocytes in other rare CNS inflammatory diseases, such as neuromyelitis optica spectrum disorder (NMOSD) and autoimmune encephalitis (AE). However, some drugs targeting cytokine receptors involved in B-lymphocyte maturation and proliferation resulted in negative outcomes in MS. These apparently conflicting findings have stimulated research on the pathophysiologic mechanisms of B lymphocytes in CNS inflammatory diseases. It has been demonstrated that B lymphocytes participate in the pathogenesis of these conditions as antigen-presenting cells, producing proinflammatory cytokines that induce Th1 and Th17 responses and producing antibodies. However, they are also able to produce anti-inflammatory cytokines, such as interleukin-10, functioning as regulators of autoimmunity. Understanding these diverse effects is essential for the development of focused treatments. In this review, we discuss the possible mechanisms that underlie B-lymphocyte involvement in MS, NMOSD, and AE and the outcomes obtained by treatments targeting B lymphocytes.

Adaptive human immunity drives remyelination in a mouse model of demyelination.

One major challenge in multiple sclerosis is to understand the cellular and molecular mechanisms leading to disease severity progression. The recently demonstrated correlation between disease severity and remyelination emphasizes the importance of identifying factors leading to a favourable outcome. Why remyelination fails or succeeds in multiple sclerosis patients remains largely unknown, mainly because remyelination has never been studied within a humanized pathological context that would recapitulate major events in plaque formation such as infiltration of inflammatory cells. Therefore, we developed a new paradigm by grafting healthy donor or multiple sclerosis patient lymphocytes in the demyelinated lesion of nude mice spinal cord. We show that lymphocytes play a major role in remyelination whose efficacy is significantly decreased in mice grafted with multiple sclerosis lymphocytes compared to those grafted with healthy donors lymphocytes. Mechanistically, we demonstrated in vitro that lymphocyte-derived mediators influenced differentiation of oligodendrocyte precursor cells through a crosstalk with microglial cells. Among mice grafted with lymphocytes from different patients, we observed diverse remyelination patterns reproducing for the first time the heterogeneity observed in multiple sclerosis patients. Comparing lymphocyte secretory profile from patients exhibiting high and low remyelination ability, we identified novel molecules involved in oligodendrocyte precursor cell differentiation and validated CCL19 as a target to improve remyelination. Specifically, exogenous CCL19 abolished oligodendrocyte precursor cell differentiation observed in patients with high remyelination pattern. Multiple sclerosis lymphocytes exhibit intrinsic capacities to coordinate myelin repair and further investigation on patients with high remyelination capacities will provide new pro-regenerative strategies.

14-3-3 Proteins regulate K2P 5.1 surface expression on T lymphocytes.

K2P 5.1 channels (also called TASK-2 or Kcnk5) have already been shown to be relevant in the pathophysiology of autoimmune disease because they are known to be upregulated on peripheral and central T lymphocytes of multiple sclerosis (MS) patients. Moreover, overexpression of K2P 5.1 channels in vitro provokes enhanced T-cell effector functions. However, the molecular mechanisms regulating intracellular K2P 5.1 channel trafficking are unknown so far. Thus, the aim of the study is to elucidate the trafficking of K2P 5.1 channels on T lymphocytes. Using mass spectrometry analysis, we have identified 14-3-3 proteins as novel binding partners of K2P 5.1 channels. We show that a non-classical 14-3-3 consensus motif (R-X-X-pT/S-x) at the channel's C-terminus allows the binding between K2P 5.1 and 14-3-3. The mutant K2P 5.1/S266A diminishes the protein-protein interaction and reduces the amplitude of membrane currents. Application of a non-peptidic 14-3-3 inhibitor (BV02) significantly reduces the number of wild-type channels in the plasma membrane, whereas the drug has no effect on the trafficking of the mutated channel. Furthermore, blocker application reduces T-cell effector functions. Taken together, we demonstrate that 14-3-3 interacts with K2P 5.1 and plays an important role in channel trafficking.

B Lymphocytes in Multiple Sclerosis: Bregs and BTLA/CD272 Expressing-CD19+ Lymphocytes Modulate Disease Severity.

B lymphocytes contribute to the pathogenesis of Multiple Sclerosis (MS) by secreting antibodies and producing cytokines. This latter function was analyzed in myelin olygodendrocyte protein (MOG)-stimulated CD19+ B lymphocytes of 71 MS patients with different disease phenotypes and 40 age-and sex-matched healthy controls (HC). Results showed that: 1) CD19+/TNFα+, CD19+/IL-12+ and CD19+/IFNγ+ lymphocytes are significantly increased in primary progressive (PP) compared to secondary progressive (SP), relapsing-remitting (RR), benign (BE) MS and HC; 2) CD19+/IL-6+ lymphocytes are significantly increased in PP, SP and RR compared to BEMS and HC; and 3) CD19+/IL-13+, CD19+/IL-10+, and CD19+/IL-10+/TGFβ+ (Bregs) B lymphocytes are reduced overall in MS patients compared to HC. B cells expressing BTLA, a receptor whose binding to HVEM inhibits TcR-initiated cytokine production, as well as CD19+/BTLA+/IL-10+ cells were also significantly overall reduced in MS patients compared to HC. Analyses performed in RRMS showed that fingolimod-induced disease remission is associated with a significant increase in Bregs, CD19+/BTLA+, and CD19+/BTLA+/IL-10+ B lymphocytes. B lymphocytes participate to the pathogenesis of MS via the secretion of functionally-diverse cytokines that might play a role in determining disease phenotypes. The impairment of Bregs and CD19+/BTLA+ cells, in particular, could play an important pathogenic role in MS.

Deimination of the myelin basic protein decelerates its proteasome-mediated metabolism.

Deimination of myelin basic protein (MBP) by peptidylarginine deiminase (PAD) prevents its binding to the proteasome and decelerates its degradation by the proteasome in mammalian cells. Potential anticancer drug tetrazole analogue of chloramidine 2, at concentrations greater than 1 µM inhibits the enzymatic activity of PAD in vitro. The observed acceleration of proteasome hydrolysis of MBP to antigenic peptides in the presence of PAD inhibitor may increase the efficiency of lesion of the central nervous system by cytotoxic lymphocytes in multiple sclerosis. We therefore suggest that clinical trials and the introduction of PAD inhibitors in clinical practice for the treatment of malignant neoplasms should be performed only after a careful analysis of their potential effect on the induction of autoimmune neurodegeneration processes.

Meningeal Tertiary Lymphoid Tissues and Multiple Sclerosis: A Gathering Place for Diverse Types of Immune Cells during CNS Autoimmunity

Collections of leukocytes in the meningeal space have been documented in Multiple Sclerosis (MS). These meningeal aggregates, which in the context of other autoimmune diseases have often been termed tertiary lymphoid tissues (TLT), have been associated with sub-pial cortical damage and disease progression. However, the key molecular and cellular signals required for their formation and maintenance remain unclear. Herein, we review TLT structures in other disease states in order to provide a framework for understanding these structures in the MS meninges. We then assess the evidence that the meningeal compartment serves as an important nexus for immune cells as well as a location for drainage of antigen into cervical lymph nodes. Extrapolating what is known about the molecular and cellular cues that initiate the formation of leukocyte aggregates in non-lymphoid tissues, we speculate on what signals lead to the formation and maintenance of meningeal TLT structures. Referring to the animal model of MS [experimental autoimmune encephalomyelitis (EAE)], we also explore what is known about these structures in supporting B cell and T cell responses during neuroinflammation. Last, we examine the evidence that connects these structures to ongoing neuropathology. Collectively, our review points to the meningeal compartment as an important player in neuroinflammatory processes. Moreover, we hypothesize that in order to gain insights into pro- and anti-inflammatory properties of lymphocytes in MS, one must understand the cellular scaffolds that support lymphocyte retention within the meninges, thus highlighting the importance of non-immune cells (stromal cells) in the neuroinflammatory process.

Neuroimmunotherapies Targeting T Cells: From Pathophysiology to Therapeutic Applications.

Therapeutic options for multiple sclerosis (MS) have significantly increased over the last few years. T lymphocytes are considered to play a central role in initiating and perpetuating the pathological immune response. Currently approved therapies for MS target T lymphocytes, either in an unspecific manner or directly by interference with specific T-cell pathways. While the concept of "T-cell-specific therapy" implies specificity and selectivity, currently approved approaches come from a general shaping of the immune system towards anti-inflammatory immune responses by non-T-cell-selective immune suppression or immune modulation (e.g., interferons-immune modulation approach) to a depletion of immune cell populations involving T cells (e.g., anti-CD52, alemtuzumab-immune selective depletion approach), or a selective inhibition of distinct molecular pathways in order to sequester leucocytes (e.g., natalizumab-leukocyte sequestration approach). This review will highlight the rationale and results of different T-cell-directed therapeutic approaches coming from basic animal experiments to clinical trials. We will first discuss the pathophysiological rationale for targeting T lymphocytes in MS leading to currently approved treatments acting on T lymphocytes. Furthermore, we will disuss previous promising concepts that have failed to show efficacy in clinical trials or were halted as a result of unexpected adverse events. Learning from the discrepancies between expectations and failures in practical outcomes helps to optimize future research approaches and clinical study designs. As our current view of MS pathogenesis and patient needs is rapidly evolving, novel therapeutic approaches targeting T lymphocytes will also be discussed, including specific molecular interventions such as cytokine-directed treatments or strategies enhancing immunoregulatory mechanisms. Based on clinical experience and novel pathophysiological approaches, T-cell-based strategies will remain a pillarstone of MS therapy.

A lipidomic approach to the study of human CD4(+) T lymphocytes in multiple sclerosis.

BackgroundLipids play different important roles in central nervous system so that dysregulation of lipid pathways has been implicated in a growing number of neurodegenerative disorders including multiple sclerosis (MS). MS is the most prevalent autoimmune disorder of the central nervous system, with neurological symptoms caused by inflammation and demyelination. In this study, a lipidomic analysis was performed for the rapid profile of CD4+ T lymphocytes from MS patient and control samples in an untargeted approach.MethodsA matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry based approach was used for the analysis of lipid extracts using 9-aminoacridine as matrix. Lipids were analyzed in negative mode and selected species fragmented using MALDI tandem mass spectrometry for their structural assignments.ResultsThe analysis reveals some modifications in the phospholipid pattern of MS CD4+ T lymphocytes with respect to healthy controls with a significant increase of cardiolipin species in MS samples.ConclusionsThese results demonstrate the feasibility of a MALDI-TOF approach for the analysis of CD4+ lipid extracts and suggest how alterations in the lipid metabolism characterized lymphocytes of MS patients.

The gut microflora determines pathogenicity in Th17-mediated CNS autoimmunity

The individual and collective roles of interferon gamma (IFNg) producing T helper (Th) 1 and interleukin 17 (IL-17) expressing Th17 lymphocytes in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), are subject to intense investigations. Here we sought to decipher the specific involvement of these Th cell subsets during manifestation and the clinical phase of EAE. For that purpose, we used recently generated double-knockout mice, which lack both IL-17A and IL-17F (IL-17AFKO).

Effects of rituximab on lymphocytes in multiple sclerosis and neuromyelitis optica

ObjectiveTo investigate the effect of rituximab, a B-cell targeted therapy that is used in the treatment of multiple sclerosis (MS) and neuromyelitis optica (NMO), on other immune cells such as CD4+ and CD8+ T-cells in patients with MS and NMO. Design, setting and patientsThis is a retrospective study of all patients with MS or NMO who received at least one rituximab infusion at the UCSF MS tertiary care center between May 2005 and July 2011. Main outcome measuresLinear mixed models were used to assess (a) how post-infusion cell counts changed over time compared to pre-infusion levels and one another; (b) whether the cell counts were different over multiple courses of rituximab; and (c) what was the dosing effect on the cell counts over time. ResultsRituximab initially reduced CD4+ (by 26%, p=0.0005) and CD8+ (by 22%, p=0.0006) T-cells, although these changes were only transient. Subsequent treatments with rituximab did not result in a significant drop in CD4+ or CD8+ T-cells. Changes in other cell types were also typically more marked after the first cycle of rituximab than after additional treatments. The total dose of rituximab received did not appear to have a significant effect. ConclusionsAlthough transient, rituximab-induced decrease in CD4+ and CD8+ T-cells may increase the risk of infection in susceptible individuals.

T cells from autoimmune patients display reduced sensitivity to immunoregulation by mesenchymal stem cells: Role of IL-2

Mesenchymal stem cells (MSCs) are multipotent progenitor cells which have been shown to possess broad immunoregulatory and anti-inflammatory capabilities, making them a promising tool to treat autoimmune diseases (AIDs). Nevertheless, as in recent years T cells from AID patients have been found to resist suppression by regulatory T cells, the question of whether they could be regulated by MSCs arises. To use MSCs as a therapeutic tool in human autoimmune diseases, one prerequisite is that T cells from autoimmune patients will be sensitive to these stem cells. The aim of this work was to investigate the ability of healthy donor derived MSCs to inhibit the proliferation of T cells from two pathophysiologically different AIDs: Multiple Sclerosis (MS) and Myasthenia Gravis (MG). We show that MSC-induced inhibition of interferon-γ production and surface expression of the CD3, CD4 and CD28 receptors by activated lymphocytes was similar in the AID patients and healthy controls. Contrarily, the MSCs' ability to suppress the proliferation of T cells of both diseases was significantly weaker compared to their ability to affect T cells of healthy individuals. Although we found that the inhibitory mechanism is mediated through CD14+ monocytes, the faulty cellular component is the patients' T cells. MSC-treated MS and MG lymphocytes were shown to produce significantly more IL-2 than healthy subjects while coupling of the MSC treatment with neutralizing IL-2 antibodies resulted in inhibition levels similar to those of the healthy controls. MSCs were also found to down-regulate the lymphocyte surface expression of the IL-2 receptor (CD25) through both transcription inhibition and induction of receptor shedding. Addition of IL-2 to MSC-inhibited lymphocytes restored proliferation thus suggesting a key role played by this cytokine in the inhibitory mechanism. Taken together, these results demonstrate the potential of a MSC-based cellular therapy for MS, MG and possibly other autoimmune diseases but also highlight the need for a better understanding of the underlying mechanisms for development and optimization of clinical protocols.

Multiple sclerosis lymphocytes upregulate A2A adenosine receptors that are antiinflammatory when stimulated

Multiple sclerosis (MS) is an autoimmune-mediated inflammatory disease characterized by multifocal areas of demyelination. Experimental evidence indicates that A2A adenosine receptors (ARs) play a pivotal role in the inhibition of inflammatory processes. The aim of this study was to investigate the contribution of A2A ARs in the inhibition of key pro-inflammatory mediators for the pathogenesis of MS. In lymphocytes from MS patients, A1, A2A, A2B, and A3 ARs were analyzed by using RT-PCR, Western blotting, immunofluorescence, and binding assays. Moreover the effect of A2A AR stimulation on proinflammatory cytokine release such as TNF-α, IFN-γ, IL-6, IL-1β, IL-17, and on lymphocyte proliferation was evaluated. The capability of an A2A AR agonist on the modulation of very late antigen (VLA)-4 expression and NF-κB was also explored. A2A AR upregulation was observed in lymphocytes from MS patients in comparison with healthy subjects. The stimulation of these receptors mediated a significant inhibition of TNF-α, IFN-γ, IL-6, IL-1β, IL-17, and cell proliferation as well as VLA-4 expression and NF-κB activation. This new evidence highlights that A2A AR agonists could represent a novel therapeutic tool for MS treatment as suggested by the antiinflammatory role of A2A ARs in lymphocytes from MS patients.

Impact of infectious agents on trafficking of effector T cells is mediated by a polymorphic site of TLR2 and CD44 isoforms expression.

Impact of infectious agents on trafficking of effector T cells is mediated by a polymorphic site of TLR2 and CD44 isoforms expression.

Implications of Lymphocyte Anergy to Glycolipids in Multiple Sclerosis (MS): iNKT Cells May Mediate the MS Infectious Trigger.

Immunogenic lipids may play key roles in host defenses against infection and in generating autoimmune inflammation and organ-specific damage. In multiple sclerosis (MS) there are unequivocal autoimmune features and vulnerability to aggravation or induction by microbial or viral infection. We have found glycolipid-driven anergy of circulating lymphocytes in MS indicating that this immune response is affected in MS and the robust effects of iNKT activation with potent cellular and cytokine activities emphasizes its potential importance. Diverse glycolipids including the endogenous myelin acetylated-galactosylceramides (AcGalCer) can drive activation that could be critical to the inflammatory demyelination in the central nervous system and clinical consequences. The iNKT cells and their invariant or iTCR (Vα24Jα18Vβ11) receptor an innate defense–a discrete immune arm that is separate from peptide-driven acquired immune responses. This offers new possibilities for insight including a likelihood that the pattern recognition of exogenous microbial and myelin immunogens can overlap and cross-react especially in an inflammatory milieu.

Altered microRNA expression in B lymphocytes in multiple sclerosis

MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression. We compared the expression of 1059 miRNAs in B lymphocytes from untreated and natalizumab treated relapsing-remitting multiple sclerosis (RRMS) patients and healthy volunteers (HV). Forty nine miRNAs were down-regulated in untreated MS patients compared with HV. A distinct pattern of 10 differentially expressed miRNAs was found in natalizumab treated patients compared with untreated patients. Two clusters, i.e. miR-106b-25 and miR-17-92, were particularly deregulated. MiRNA-mRNA interaction analysis revealed B cell receptor, phosphatidyl-inositol-3-kinase (PI3K) and phosphatase and tensin homology (PTEN) signaling being the key affected pathways. We discovered deregulated viral miRNAs in untreated patients as compared with HV and natalizumab treated patients, a novel finding that may be related to latency and activation of viruses in MS. Our findings provide first insights into miRNA dependent regulation of B cell function in MS and the impact of a therapy not primarily targeting B cells on this regulation.

Dopaminergic Modulation of CD4+CD25high Regulatory T Lymphocytes in Multiple Sclerosis Patients during Interferon-β Therapy

Objective: We investigated dopaminergic inhibition of CD4+CD25^high regulatory T lymphocytes (Treg) in relapsing-remitting multiple sclerosis (MS) patients treated with interferon (IFN)-β. Methods: MS patients were prospectively studied at baseline and during 1 year of IFN-β, and compared with healthy controls (HCs). Treg were separated by immunomagnetic sorting and the effect of dopamine (DA) on Treg was assessed in coculture experiments with homologous effector T lymphocytes (Teff). Tyrosine hydroxylase (TH), dopaminergic receptors (DR) D3 and D5, and forkhead box protein P3 (FoxP3) mRNA were assessed by real-time PCR. Circulating CD4+ T cell subsets were assessed by flow cytometry. Results: In coculture experiments, Treg inhibition of Teff proliferation was reduced by DA in HCs and completely abolished in MS patients at baseline. However, in patients after 12 months of IFN-β, Teff proliferation was impaired and DA had no more effect on Treg. In comparison to cells from HCs, Treg from MS patients at baseline had increased mRNA for DR D5 and TH (but not for DR D3). During treatment with IFN-β, both DR D5 and TH mRNA decreased down to values lower than those of cells from HCs. In comparison to HCs, MS patients had a higher frequency of circulating Treg, both at baseline and after IFN-β, while FoxP3 mRNA levels in Treg were similar in patients and HCs and did not show major changes during IFN-β. Conclusions: Dopaminergic inhibition of Treg in MS patients is suppressed during IFN-β treatment. Treg play a key role in the suppression of autoimmunity, thus the effect may have a therapeutic repercussion.