Soluble CD27 is an intrathecal biomarker of T-cell-mediated lesion activity in multiple sclerosis.

OBJECTIVE: Soluble CD27 is a promising cerebrospinal fluid inflammatory biomarker in multiple sclerosis. In this study, we investigate relevant immune and neuro-pathological features of soluble CD27 in multiple sclerosis. METHODS: Protein levels of soluble CD27 were correlated to inflammatory cell subpopulations and inflammatory cytokines and chemokines detected in cerebrospinal fluid of 137 patients with multiple sclerosis and 47 patients with inflammatory and non-inflammatory neurological disease from three independent cohorts. Production of soluble CD27 was investigated in cell cultures of activated T and B cells and CD27-knockout T cells. In a study including matched cerebrospinal fluid and post-mortem brain tissues of patients with multiple sclerosis and control cases, levels of soluble CD27 were correlated with perivascular and meningeal infiltrates and with neuropathological features. RESULTS: We demonstrate that soluble CD27 favours the differentiation of interferon-γ-producing T cells and is released through a secretory mechanism activated by TCR engagement and regulated by neutral sphingomyelinase. We also show that the levels of soluble CD27 correlate with the representation of inflammatory T cell subsets in the CSF of patients with relapsing-remitting multiple sclerosis and with the magnitude of perivascular and meningeal CD27 + CD4 + and CD8 + T cell infiltrates in post-mortem central nervous system tissue, defining a subgroup of patients with extensive active inflammatory lesions. INTERPRETATION: Our results demonstrate that soluble CD27 is a biomarker of disease activity, potentially informative for personalized treatment and monitoring of treatment outcomes.

B cells in multiple sclerosis - from targeted depletion to immune reconstitution therapies.

Increasing evidence indicates the involvement of B cells in the pathogenesis of multiple sclerosis (MS), but their precise roles are unclear. In this Review, we provide an overview of the development and physiological functions of B cells and the main mechanisms through which B cells are thought to contribute to CNS autoimmunity. In MS, abnormalities of B cell function include pro-inflammatory cytokine production, defective B cell regulatory function and the formation of tertiary lymphoid-like structures in the CNS, which are the likely source of abnormal immunoglobulin production detectable in the cerebrospinal fluid. We also consider the hypothesis that Epstein-Barr virus (EBV) is involved in the B cell overactivation that leads to inflammatory injury to the CNS in MS. We also review the immunological effects - with a focus on the effects on B cell subsets - of several successful therapeutic approaches in MS, including agents that selectively deplete B cells (rituximab, ocrelizumab and ofatumumab), agents that less specifically deplete lymphocytes (alemtuzumab and cladribine) and autologous haematopoietic stem cell transplantation, in which the immune system is unselectively ablated and reconstituted. We consider the insights that these effects on B cell populations provide and their potential to further our understanding and targeting of B cells in MS.

Worse Physical Disability Is Associated With the Expression of PD-1 on Inflammatory T-Cells in Multiple Sclerosis Patients With Older Appearing Brains.

Background: Magnetic Resonance Imaging (MRI) analysis method "brain-age" paradigm could offer an intuitive prognostic metric (brain-predicted age difference: brain-PAD) for disability in Multiple Sclerosis (MS), reflecting structural brain health adjusted for aging. Equally, cellular senescence has been reported in MS using T-cell biomarker CD8+CD57+. Objective: Here we explored links between MRI-derived brain-age and blood-derived cellular senescence. We examined the value of combining brain-PAD with CD8+CD57+(ILT2+PD-1+) T-cells when predicting disability score in MS and considered whether age-related biological mechanisms drive disability. Methods: Brain-age analysis was applied to T1-weighted MRI images. Disability was assessed and peripheral blood was examined for CD8+CD57+ T-cell phenotypes. Linear regression models were used, adjusted for sex, age and normalized brain volume. Results: We included 179 mainly relapsing-remitting MS patients. A high brain-PAD was associated with high physical disability (mean brain-PAD = +6.54 [5.12-7.95]). CD8+CD57+(ILT2+PD-1+) T-cell frequency was neither associated with disability nor with brain-PAD. Physical disability was predicted by the interaction between brain-PAD and CD8+CD57+ILT2+PD-1+ T-cell frequency (AR 2 = 0.196), yet without improvement compared to brain-PAD alone (AR 2 = 0.206; AICc = 1.8). Conclusion: Higher frequency of CD8+CD57+ILT2+PD-1+ T-cells in the peripheral blood in patients with an older appearing brain was associated with worse disability scores, suggesting a role of these cells in the development of disability in MS patients with poorer brain health.

Defective CD19+CD24hiCD38hi transitional B-cell function in patients with relapsing-remitting MS.

BACKGROUND: Multiple sclerosis (MS) is characterized by central nervous system (CNS) infiltration of T and B cells, excess inflammatory cytokine and chemokine production and failure of immune regulation. CD19+CD24hiCD38hi transitional B cells producing interleukin (IL)-10 have been shown to suppress interferon-γ (IFNγ) and tumour necrosis factor-α (TNFα) production by CD4+ T cells and to be dysfunctional in autoimmune arthritis and systemic lupus erythematosus. OBJECTIVE: We hypothesized that transitional B-cell-dependent immune regulation could be defective in MS and examined their function in healthy subjects and patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: A total of 62 healthy donors and 21 RRMS subjects donated peripheral blood for the study. IL-10-producing B cells, IFNγ and TNFα-producing T cells and proliferating T cells were quantified by flow cytometry. RESULTS: In healthy individuals, CD19+CD24hiCD38hi transitional B cells produce more IL-10 than CD19+CD24+CD38+ naive and CD19+CD24hiCD38- memory B cells and are able to suppress CD4+ T-cell proliferation and IFNγ and TNFα-production. In subjects with RRMS, CD19+CD24hiCD38hi transitional B cells produce significantly less IL-10 and to fail to suppress effector T-cell function. CONCLUSION: CD19+CD24hiCD38hi transitional B cells physiologically represent the most potent regulatory B-cell subset and are functionally defective in patients with RRMS, an abnormality that may contribute to the immune pathological process.

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.

Programmed death 1 is highly expressed on CD8+ CD57+ T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus.

Growing evidence points to a deregulated response to Epstein-Barr virus (EBV) in the central nervous system of patients with multiple sclerosis (MS) as a possible cause of disease. We have investigated the response of a subpopulation of effector CD8+ T cells to EBV in 36 healthy donors and in 35 patients with MS in active and inactive disease. We have measured the expression of markers of degranulation, the release of cytokines, cytotoxicity and the regulation of effector functions by inhibitory receptors, such as programmed death 1 (PD-1) and human inhibitor receptor immunoglobulin-like transcript 2 (ILT2). We demonstrate that polyfunctional cytotoxic CD8+ CD57+ T cells are able to kill EBV-infected cells in healthy donors. In contrast, an anergic exhaustion-like phenotype of CD8+ CD57+ T cells with high expression of PD-1 was observed in inactive patients with MS compared with active patients with MS or healthy donors. Detection of CD8+ CD57+ T cells in meningeal inflammatory infiltrates from post-mortem MS tissue confirmed the association of this cell phenotype with the disease pathological process. The overall results suggest that ineffective immune control of EBV in patietns with MS during remission may be one factor preceding and enabling the reactivation of the virus in the central nervous system and may cause exacerbation of the disease.

The load of amyloid-ß oligomers is decreased in the cerebrospinal fluid of Alzheimer's disease patients.

Amyloid-ß (Aß) oligomers are heterogeneous and instable compounds of variable molecular weight. Flow cytometry and fluorescence resonance energy transfer (FRET)-based methods allow the simultaneous detection of Aß oligomers with low and high molecular weight in their native form. We evaluated whether an estimate of different species of Aß oligomers in the cerebrospinal fluid (CSF) with or without dilution with RIPA buffer could be more useful in the diagnosis of Alzheimer's disease (AD) than the measurement of Aß42 monomers, total tau (t-tau), and phosphorylated tau (p-tau). Increased t-tau (p < 0.01) and p-tau (p < 0.01), and decreased Aß42 (p < 0.01), were detected in the CSF of patients with AD (n = 46), compared to patients with other dementia (OD) (n = 35) or with other neurological disorders (OND) (n = 56). In native CSF (n = 137), the levels of Aß oligomers were lower (p < 0.05) in AD than in OD and OND patients; in addition, the ratio Aß oligomers/p-tau was lower in AD than in OD (p < 0.01) and OND (p < 0.05) patients, yielding a sensitivity of 75% and a specificity of 64%. However, in CSF diluted with RIPA (n = 30), Aß oligomers appeared higher (p < 0.05) in AD than in OND patients, suggesting they become partially disaggregated and more easily detectable after RIPA. In conclusion, FRET analysis in native CSF is essential to correctly determine the composition of Aß oligomers. In this experimental setting, the simultaneous estimate of low and high molecular weight Aß oligomers is as useful as the other biomarkers in the diagnosis of AD. The low amount of Aß oligomers detected in native CSF of AD may be inversely related to their levels in the brain, as occurs for Aß monomers, representing a biomarker for the amyloid pathogenic cascade.

Homing and memory patterns of human gammadelta T cells in physiopathological situations.

Vgamma9Vdelta2 are a heterogeneous population of T cells and comprise distinct naive, memory and effector populations that can be distinguished on the basis of surface marker expression and effector functions. We review here these recently studied features of Vgamma9Vdelta2 T lymphocyte biology and the roles they play in infectious and autoimmune diseases.