Search

Background and Objectives: Ocrelizumab (OCR), a humanized anti-CD20 monoclonal antibody, is highly efficient in patients with relapsing-remitting multiple sclerosis (RR-MS). We assessed early cellular immune profiles and their association with disease activity at treatment start and under therapy, which may provide new clues on the mechanisms of action of OCR and on the disease pathophysiology., Methods: A first group of 42 patients with an early RR-MS, never exposed to disease-modifying therapy, was included in 11 centers participating to an ancillary study of the ENSEMBLE trial (NCT03085810) to evaluate the effectiveness and safety of OCR. The phenotypic immune profile was comprehensively assessed by multiparametric spectral flow cytometry at baseline and after 24 and 48 weeks of OCR treatment on cryopreserved peripheral blood mononuclear cells and analyzed in relation to disease clinical activity. A second group of 13 untreated patients with RR-MS was included for comparative analysis of peripheral blood and CSF. The transcriptomic profile was assessed by single-cell qPCRs of 96 genes of immunologic interest., Results: Using an unbiased analysis, we found that OCR as an effect on 4 clusters of CD4 + T cells: one corresponding to naive CD4 + T cells was increased, the other clusters corresponded to effector memory (EM) CD4 + CCR6 - T cells expressing homing and migration markers, 2 of them also expressing CCR5 and were decreased by the treatment. Of interest, one CD8 + T-cell cluster was decreased by OCR corresponding to EM CCR5-expressing T cells with high expression of the brain homing markers CD49d and CD11a and correlated with the time elapsed since the last relapse. These EM CD8 + CCR5 + T cells were enriched in the CSF of patients with RR-MS and corresponded to activated and cytotoxic cells., Discussion: Our study provides novel insights into the mode of action of anti-CD20, pointing toward the role of EM T cells, particularly a subset of CD8 T cells expressing CCR5., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Background and Objectives: Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the CNS. Studies of immune dysfunction in MS have mostly focused on CD4 + Tregs, but the role of CD8 + Tregs remains largely unexplored. We previously evidenced the suppressive properties of rat and human CD8 + CD45RC low/neg Tregs from healthy individuals, expressing Forkhead box P3 (FOXP3) and acting through interferon-gamma (IFN-γ), transforming growth factor beta (TGFβ), and interleukin-34 (IL-34). secretions to regulate immune responses and control diseases such as transplant rejection. To better understand CD8 + CD45RC low/neg Tregs contribution to MS pathology, we further investigated their phenotype, function, and transcriptome in patients with MS., Methods: We enrolled adults with relapsing-remitting MS and age-matched and sex-matched healthy volunteers (HVs). CD8 + T cells were segregated based on low or lack of expression of CD45RC. First, the frequency in CSF and blood, phenotype, transcriptome, and function of CD8 + CD45RC low and neg were investigated according to exacerbation status and secondarily, according to clinical severity based on the MS severity score (MSSS) in patients with nonexacerbating MS. We then induced active MOG 35-55 EAE in C57Bl/6 mice and performed adoptive transfer of fresh and expanded CD8 + CD45RC neg Tregs to assess their ability to mitigate neuroinflammation in vivo., Results: Thirty-one untreated patients with relapsing-remitting MS were compared with 40 age-matched and sex-matched HVs. We demonstrated no difference of CSF CD8 + CD45RC low and CD8 + CD45RC neg proportions, but blood CD8 + CD45RC low frequency was lower in patients with MS exacerbation when compared with that in HVs. CD8 + CD45RC neg Tregs but not CD8 + CD45RC low showed higher suppressive capacities in vitro in MS patients with exacerbation than in patients without acute inflammatory attack. In vitro functional assays showed a compromised suppression capacity of CD8 + CD45RC low Tregs in patients with nonexacerbating severe MS, defined by the MSSS. We then characterized murine CD8 + CD45RC neg Tregs and demonstrated the potential of CD45RC neg cells to migrate to the CNS and mitigate experimental autoimmune encephalomyelitis in vivo., Discussion: Altogether, these results suggest a defect in the number and function of CD8 + CD45RC low Tregs during MS relapse and an association of CD8 + CD45RC low Tregs dysfunction with MS severity. Thus, CD8 + CD45RC low/neg T cells might bring new insights into the pathophysiology and new therapeutic approaches of MS., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Several lines of evidence support a key role for CD8 + T cells in central nervous system tissue damage of patients with multiple sclerosis. However, the precise phenotype of the circulating CD8 + T cells that may be recruited from the peripheral blood to invade the CNS remains largely undefined to date. It has been suggested that IL-17 secreting CD8 (Tc17) T cells may be involved, and in humans these cells are characterized by the expression of CD161. We focused our study on a unique and recently described subset of CD8 T cells characterized by an intermediate expression of CD161 as its role in neuroinflammation has not been investigated to date. The frequency, phenotype, and function of CD8 + T cells with an intermediate CD161 expression level were characterized ex-vivo, in vitro, and in situ using RNAseq, RT-PCR, flow cytometry, TCR sequencing, and immunohistofluorescence of cells derived from healthy volunteers (n = 61), MS subjects (n = 90), as well as inflammatory (n = 15) and non-inflammatory controls (n = 6). We report here that CD8 + CD161 int T cells present characteristics of effector cells, up-regulate cell-adhesion molecules and have an increased ability to cross the blood-brain barrier and to secrete IL-17, IFNγ, GM-CSF, and IL-22. We further demonstrate that these cells are recruited and enriched in the CNS of MS subjects where they produce IL-17. In the peripheral blood, RNAseq, RT-PCR, high-throughput TCR repertoire analyses, and flow cytometry confirmed an increased effector and transmigration pattern of these cells in MS patients, with the presence of supernumerary clones compared to healthy controls. Our data demonstrate that intermediate levels of CD161 expression identifies activated and effector CD8 + T cells with pathogenic properties that are recruited to MS lesions. This suggests that CD161 may represent a biomarker and a valid target for the treatment of neuroinflammation., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The involvement of Mucosal Associated Invariant T (MAIT) cells, which are anti-microbial semi-invariant T cells, remains elusive in Multiple Sclerosis (MS)., Objective: Deciphering the potential involvement of MAIT cells in the MS inflammatory process., Methods: By flow cytometry, blood MAIT cells from similar cohorts of MS patients and healthy volunteers (HV) were compared for frequency, phenotype, activation potential after in vitro TCR engagement by bacterial ligands and transmigration abilities through an in vitro model of blood-brain barrier. MS CNS samples were also studied by immunofluorescent staining and quantitative PCR., Results and Conclusion: Blood MAIT cells from relapsing-remitting MS patients and HV presented similar frequency, ex vivo effector phenotype and activation abilities. MAIT cells represented 0.5% of the total infiltrating T cells on 39 MS CNS lesions. This is low as compared to blood frequency (p<0.001), but consistent with their low transmigration rate. Finally, transcriptional over-expression of MR1 - which presents cognate antigens to MAIT cells - and of the activating cytokines IL-18 and IL-23 was evidenced in MS lesions, suggesting that the CNS microenvironment is suited to activate the few infiltrating MAIT cells. Taken together, these data place MAIT cells from MS patients as minor components of the inflammatory pathological process., (Copyright © 2016 Elsevier Inc. All rights reserved.)