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The trafficking of autoreactive leucocytes across the blood–brain barrier endothelium is a hallmark of multiple sclerosis pathogenesis. Although the blood–brain barrier endothelium represents one of the main CNS borders to interact with the infiltrating leucocytes, its exact contribution to neuroinflammation remains understudied. Here, we show that Mcam identifies inflammatory brain endothelial cells with pro-migratory transcriptomic signature during experimental autoimmune encephalomyelitis. In addition, MCAM was preferentially upregulated on blood–brain barrier endothelial cells in multiple sclerosis lesions in situ and at experimental autoimmune encephalomyelitis disease onset by molecular MRI. In vitro and in vivo, we demonstrate that MCAM on blood–brain barrier endothelial cells contributes to experimental autoimmune encephalomyelitis development by promoting the cellular trafficking of TH1 and TH17 lymphocytes across the blood–brain barrier. Last, we showcase ST14 as an immune ligand to brain endothelial MCAM, enriched on CD4+ T lymphocytes that cross the blood–brain barrier in vitro, in vivo and in multiple sclerosis lesions as detected by flow cytometry on rapid autopsy derived brain tissue from multiple sclerosis patients. Collectively, our findings reveal that MCAM is at the centre of a pathological pathway used by brain endothelial cells to recruit pathogenic CD4+ T lymphocyte from circulation early during neuroinflammation. The therapeutic targeting of this mechanism is a promising avenue to treat multiple sclerosis.

Background and ObjectivesIn multiple sclerosis (MS), peripheral immune cells use various cell trafficking molecules to infiltrate the CNS where they cause damage.The objective of this study was to investigate the involvement of coxsackie and adenovirus receptor–like membrane protein (CLMP) in the migration of immune cells into the CNS of patients with MS.MethodsExpression of CLMP was measured in primary cultures of human brain endothelial cells (HBECs) and human meningeal endothelial cells (HMECs), postmortem brain samples, and peripheral blood mononuclear cells (PBMCs) from patients with MS and controls by RNA sequencing, quantitative PCR, immunohistochemistry, and flow cytometry. In vitro migration assays using HBECs and HMECs were performed to evaluate the function of CLMP.ResultsUsing bulk RNA sequencing of primary cultures of human brain and meningeal endothelial cells (ECs), we have identified CLMP as a new potential cell trafficking molecule upregulated in inflammatory conditions. We first confirmed the upregulation of CLMP at the protein level on TNFα-activated and IFNγ-activated primary cultures of human brain and meningeal ECs. In autopsy brain specimens from patients with MS, we demonstrated an overexpression of endothelial CLMP in active MS lesions when compared with normal control brain tissue. Flow cytometry of human PBMCs demonstrated an increased frequency of CLMP+ B lymphocytes and monocytes in patients with MS, when compared with that in healthy controls. The use of a blocking antibody against CLMP reduced the migration of immune cells across the human brain and meningeal ECs in vitro. Finally, we found CLMP+ immune cell infiltrates in the perivascular area of parenchymal lesions and in the meninges of patients with MS.DiscussionCollectively, our data demonstrate that CLMP is an adhesion molecule used by immune cells to access the CNS during neuroinflammatory disorders such as MS. CLMP could represent a target for a new treatment of neuroinflammatory conditions.

Background Inhibition of dihydroorotate dehydrogenase (DHODH) is an established mechanism for the treatment of relapsing-remitting multiple sclerosis (RRMS). Currently approved treatments have several shortcomings. Consequently, new and effective treatments with improved safety and convenience profiles are sought after by patients. Objective To explore the overall profile of vidofludimus for the treatment of RRMS. Methods Preclinical investigations were done exploring the species-dependency of DHODH inhibition of vidofludimus. In addition, the preclinical efficacy in a rat experimental autoimmune encephalomyelitis (EAE) model and the inhibition of cytokine release from activated PBMC were investigated. Pharmacokinetic data were also obtained in a Phase 1 multiple ascending dose trial of the formulation IMU–838 (vidofludimus calcium). Results It was shown that vidofludimus is 2.6 times more potent in inhibiting DHO oxidation by human DHODH compared to teriflunomide. Although both compounds increased cell apoptosis, vidofludimus was more efficacious in the inhibition of T-lymphocyte proliferation compared to teriflunomide. The same was also observed for the secretion of IL–17 and IFN–γ. Interestingly, the potency or vidofludimus to inhibit rat or mouse DHODH is 7.5 and 64.4 time lower than the for the human DHODH, respectively. The rat EAE study clearly exhibited a dose-dependent inhibition of cumulative disease scores by vidofludimus. In the multiple ascending dose Phase 1 clinical trial, the serum half-life of about 30 h provides a favorable profile for once daily dosing of IMU–838, with quick dosing to steady state through levels within 5 days and the ability to wash out drug quickly, if required. Conclusions The investigations highlighted that the desired selective immunomodulatory properties can be separated from general antiproliferative effects seen and related adverse events in first-generation DHODH inhibitors. Based on data obtained from a series of pre-clinical as well as phase 1 and phase 2 studies, IMU–838 is a promising next-generation candidate for the oral treatment of RRMS. However, this will need to be confirmed in the currently ongoing Phase 2 study in RRMS patients.

Objective To investigate the involvement of interleukin (IL)-26 in neuroinflammatory processes in multiple sclerosis (MS), in particular in blood-brain barrier (BBB) integrity. Methods Expression of IL-26 was measured in serum, CSF, in vitro differentiated T helper (T-H) cell subsets, and postmortem brain tissue of patients with MS and controls by ELISA, quantitative PCR, and immunohistochemistry. Primary human and mouse BBB endothelial cells (ECs) were treated with IL-26 in vitro and assessed for BBB integrity. RNA sequencing was performed on IL-26-treated human BBB ECs. Myelin oligodendrocyte glycoprotein(35-55) experimental autoimmune encephalomyelitis (EAE) mice were injected IP with IL-26. BBB leakage and immune cell infiltration were assessed in the CNS of these mice using immunohistochemistry and flow cytometry. Results IL-26 expression was induced in T-H lymphocytes by T(H)17-inducing cytokines and was upregulated in the blood and CSF of patients with MS. CD4(+)IL-26(+) T lymphocytes were found in perivascular infiltrates in MS brain lesions, and both receptor chains for IL-26 (IL-10R2 and IL-20R1) were detected on BBB ECs in vitro and in situ. In contrast to IL-17 and IL-22, IL-26 promoted integrity and reduced permeability of BBB ECs in vitro and in vivo. In EAE, IL-26 reduced disease severity and proinflammatory lymphocyte infiltration into the CNS, while increasing infiltration of Tregs. Conclusions Our study demonstrates that although IL-26 is preferentially expressed by T(H)17 lymphocytes, it promotes BBB integrity in vitro and in vivo and is protective in chronic EAE, highlighting the functional diversity of cytokines produced by T(H)17 lymphocytes. This work was funded by a grant from the Canadian Institutes of Health Research (MOP136980). A. Prat holds a senior Canada Research Chair in Multiple Sclerosis. M. Charabati held a postdoctoral studentship from the Fonds de recherche du Quebec-Sante (FRQS) and is now supported by a doctoral scholarship from the Multiple Sclerosis Society of Canada (MSSC). E. Peelen and S. Zandee held a postdoctoral studentship from the FRQS/MSSC Partnership Award. B. Broux held a postdoctoral studentship from Fonds Wetenschappelijk Onderzoek-Vlaanderen. L. Hachehouche held PhD studentships from the MSSC, FRQS, and Neuroinflammation Training Program. Prat, A (corresponding author), Univ Montreal, Fac Med, Multiple Sclerosis Clin, Res Ctr,Ctr Hosp Univ Montreal CRCHUM,Dept Neuros, Montreal, PQ, Canada. a.prat@umontreal.ca

Introduction Vascular comorbidities are prevalent among people with multiple sclerosis (MS) and have adverse disease-related consequences. In the general population, physical activity (PA) and exercise training have proven beneficial at all levels of vascular disease risk management. People with MS exhibit particularly low rates of PA; therefore, PA represents a modifiable health behavior for potentially managing vascular comorbidity risk in MS, and in turn, reducing disease burden. However, points of evidence justifying such an approach have yet to be summarized. Objective To conduct a scoping review of existing evidence linking PA and exercise training to potential modification of vascular comorbidities and related risk factors in people with MS. Methods We searched five electronic databases (PubMed, Ovid MEDLINE, Embase, PsycINFO, and CINAHL Plus) from inception to November 2017, for articles involving relevant vascular comorbidities (obesity, hyperlipidemia, heart disease, hypertension, and diabetes) in people with MS in conjunction with measures of PA, physical fitness, sedentary behavior, or exercise training. Studies were limited to English-language and primary research articles. Data were extracted and summarized by comorbidity type and study design (observational vs. interventional). Results Our initial search identified 1028 articles; subsequent screening resulted in 34 articles meeting the final inclusion criteria, including both observational (n = 17) and interventional (n = 17) studies. Most of the articles reported on obesity (n = 29), although evidence surrounding hyperlipidemia (n = 5), arterial function and hypertension (n = 5), and diabetes (n = 5) was also identified. Data supporting a beneficial role for PA or exercise training could be drawn from each comorbidity category. Overall, 14 of the 17 observational studies identified (82.4%) reported an association between higher levels of PA or cardiorespiratory fitness, or decreased sedentary behavior, and better function of at least one risk factor related to vascular comorbid conditions in people with MS. The efficacy of exercise training in limiting vascular comorbidity risk and burden was dependent upon intervention type and duration, with 9 of 17 interventional studies (52.9%) reporting improvement in at least one relevant measure of vascular comorbidity in participants with MS. Conclusions Evidence points to a potential relationship between PA and exercise and risk factors related to vascular comorbidities in people with MS. PA and exercise training interventions may represent an effective therapeutic strategy for managing vascular comorbidities in people with MS, justifying further investigation.

BACKGROUND/OBJECTIVE: Data from animal models of MS suggest that GM-CSF(+)CD4(+)T cells are pathogenic cells. Therefore, GM-CSF production by CD4(+)T cells of MS patients and their susceptibility to regulatory mechanisms were investigated. METHODS: Intracellular flowcytometry was performed to determine the GM-CSF(+)CD4(+)T cell fraction in PBMC and CSF of MS patients and controls. The effect of regulatory T cells (Tregs) on GM-CSF production by CD4(+)T cells was studied in MS patients using a proliferation-suppression assay. Finally, GM-CSF(+)CD4(+)T cell fraction and GM-CSF protein levels in supernatant were assessed in anti-CD3-stimulated CD4(+)T cell cultures derived from healthy controls and MS patients, in the presence or absence of the active vitamin D metabolite calcitriol. RESULTS: The GM-CSF(+)CD4(+)T cell fraction in the peripheral blood did not differ between controls and MS patients. This T cell population could also be detected in the CSF of both subjects with MS as well as subjects with another diagnosis. In the CSF, it comprised a significant fraction of the T cell population. Upon in vitro stimulation of PBMC with anti-CD3 antibody, no differences were observed in GM-CSF(+)CD4(+)T cell frequencies. GM-CSF secretion was susceptible to regulation by Treg and vitamin D. Suppression of GM-CSF secretion by vitamin D was reduced in MS patients. CONCLUSIONS: Our study showed no elevation in GM-CSF(+)CD4(+)T cell fractions in MS patients compared to controls. Furthermore, GM-CSF secretion was prone to regulation by Treg and vitamin D, the latter being less effective in MS patients.

Background: A low vitamin D status has been associated with multiple sclerosis (MS). Most circulating vitamin D metabolites are bound to vitamin D binding protein (DBP). Objectives: The purpose of this study was to explore whether there is an association between MS and DBP. Methods: We compared DBP concentrations in blood samples of controls ( n = 30) and subjects with relapsing–remitting MS (RRMS) during remission ( n = 29) and relapse ( n = 15). Furthermore, we explored correlations of DBP with 25- hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D levels (1,25(OH)2D), and the effect of high-dose vitamin D3 supplementation on DBP levels in RRMS patients ( n = 15). Results: DBP-concentration did not differ between the sub-groups measured, and there was no correlation between DBP and vitamin D metabolite concentration within the physiological range. Upon supplementation of high doses vitamin D3, DBP concentration remained unaltered. After supplementation, serum 1,25(OH)2D( R = 0.517, p = 0.049), but not 25(OH)D, correlated positively with DBP. Conclusions: We found no association between DBP, MS, and vitamin D status within the physiological range. After high - dose vitamin D supplementation, DBP concentrations may be relevant for vitamin D metabolism.

In this study, we assessed B cell subsets, including Bregs, during stable and active disease in relapsing remitting multiple sclerosis (RRMS) patients and related B cell subsets to vitamin D status. We report that RRMS patients have a decreased percentage of both memory B cells and Bregs compared to healthy controls. During a relapse, the reduction in Bregs involved in particular naive Bregs. We found no correlation between vitamin D status and B cell subsets. An effect of vitamin D on Bregs cannot be ruled out, since it might be the function that is interfered with instead of relative numbers.

An impaired vitamin D (vit-D) processing by immune cells of relapsing remitting multiple sclerosis (RRMS) patients may increase their vulnerability for a poor vit-D status. We assessed with qPCR the expression of vit-D related genes in PBMC and CD4(+) T-cells. Gene expression profiles of vit-D receptor (VDR), CYP27B1 and CYP24A1 did not differ between RRMS patients and healthy controls. Interestingly, more VDR expression in PBMC correlated with less circulating IFN-gamma(+) CD4(+) T-cells. Our results suggest that vit-D processing by immune cells is not impaired in RRMS, and is potentially relevant for the composition of the peripheral CD4(+) T-cell compartment. (C) 2011 Elsevier B.V. All rights reserved.

Background: Vitamin D has been proposed as a promoter of immune homeostasis in multiple sclerosis (MS). During the past decade, the focus of the effects of vitamin D has been on dendritic cells and on T cells. Since there is an increasing interest in the role of B cells in the pathophysiology of MS, we studied the role of vitamin D on B cells in vivo in patients with MS. Objective: We explored the effects of 12 weeks high-dose vitamin D3 supplementation on peripheral B cell differentiation, immunoglobulin production and levels of B cell activating factor (BAFF) in 15 patients with MS. Methods: Circulating B cell subsets were characterized by flow cytometry. Plasma immunoglobulin levels were assessed by nephelometry. Plasma BAFF levels were assessed by enzyme-linked immunosorbent assay (ELISA). Results: Although a significant increase serum 25-hydroxyvitamin D was induced, we found no significant shift in B cell differentiation, isotype switching, or plasma BAFF levels. Conclusion: In patients with MS, supplementation of high doses vitamin D3 does not have substantial effects on phenotypic markers of B cell differentiation in circulating B cells. Future studies may unravel more subtle changes in the B cell compartment, either in the circulation or in the central nervous system.

In the present study, circulating proportions of CD8+ T (Tc) cell subsets, including IL-17 (Tc17) and IL-10 (Tc10) producing cells, were assessed in relapsing–remitting MS (RRMS) patients and a possible effect of beta interferon (IFN-β), glatiramer acetate (GA), and vitamin D (VitD) on these cell subsets was investigated. We show that both Tc17 and Tc10 cell fractions are elevated in the circulation of RRMS patients in remission compared to healthy subjects and that these Tc subsets remain unaffected by current immune modulating regimens.

In this study, percentages of CD39(+) Treg and Th17 cells were compared between relapsing-remitting MS patients and controls and were related to the vitamin D status. The Th17 cell population was expanded in about 40% of the MS patients. In MS patients in remission, but not during relapse, a positive association was found between Th17 cell and CD39(+) Treg percentages (r=0.468, p=0.007). Since CD39(+) Tregs have been shown to have Th17 suppressive capacities, we propose that a dysregulated Th17/CD39(+) Treg balance might contribute to disease exacerbation. A clear role for vitamin D in this regulation could not be established.