Treatment with MOG-DNA vaccines induces CD4+CD25+FoxP3+ regulatory T cells and up-regulates genes with neuroprotective functions in experimental autoimmune encephalomyelitis.

BACKGROUND: DNA vaccines represent promising therapeutic strategies in autoimmune disorders such as multiple sclerosis (MS). However, the precise mechanisms by which DNA vaccines induce immune regulation remain largely unknown. Here, we aimed to expand previous knowledge existing on the mechanisms of action of DNA vaccines in the animal model of MS, experimental autoimmune encephalomyelitis (EAE), by treating EAE mice with a DNA vaccine encoding the myelin oligodendrocyte glycoprotein (MOG), and exploring the therapeutic effects on the disease-induced inflammatory and neurodegenerative changes. METHODS: EAE was induced in C57BL6/J mice by immunization with MOG35₋55 peptide. Mice were intramuscularly treated with a MOG-DNA vaccine or vehicle in prophylactic and therapeutic approaches. Histological studies were performed in central nervous system (CNS) tissue. Cytokine production and regulatory T cell (Treg) quantification were achieved by flow cytometry. Gene expression patterns were determined using microarrays, and the main findings were validated by real-time PCR. RESULTS: MOG-DNA treatment reduced the clinical and histopathological signs of EAE when administered in both prophylactic and therapeutic settings. Suppression of clinical EAE was associated with dampening of antigen (Ag)-specific proinflammatory Th1 and Th17 immune responses and, interestingly, expansion of Treg in the periphery and upregulation in the CNS of genes encoding neurotrophic factors and proteins involved in remyelination. CONCLUSIONS: These results suggest for the first time that the beneficial effects of DNA vaccines in EAE are not limited to anti-inflammatory mechanisms, and DNA vaccines may also exert positive effects through hitherto unknown neuroprotective mechanisms.

Corrigendum: Monitoring T-Cell Responses in Translational Studies: Optimization of Dye-Based Proliferation Assay for Evaluation of Antigen-Specific Responses.

[This corrects the article on p. 1870 in vol. 8, PMID: 29312346.].

Predicting therapeutic response to fingolimod treatment in multiple sclerosis patients.

AIMS: Fingolimod, an orally active immunomodulatory drug for relapsing-remitting multiple sclerosis (RRMS), sequesters T cells in lymph nodes through functional antagonism of the sphingosine-1-phosphate receptor, reducing the number of potential autoreactive cells that migrate to the central nervous system. However, not all RRMS patients respond to this therapy. Our aim was to test the hypothesis that by immune-monitoring RRMS patient's leukocyte subpopulations it is possible to find biomarkers associated with clinical response to fingolimod. METHODS: Prospective study. Analysis of peripheral blood mononuclear cell subpopulations by multiparametric flow cytometry, at baseline and +1, +3, +6, +12 months of follow-up in 40 RRMS patients starting fingolimod therapy. RESULTS: Fingolimod treatment induced a severe lymphopenia affecting mainly T and B cells. A relative increase in Treg (memory Treg : 3.8 ± 1.0% baseline vs 8.8 ± 4.4% month +1; activated Treg : 1.5 ± 0.7% baseline vs 3.7 ± 2.1% month +1, P < 0.001) as well as transitional B cells (10.5 ± 12.3% baseline vs 18.7 ± 14.6% month +1, P < 0.001) was observed. Interestingly, lymphocyte subpopulations were already at baseline significantly different in responder patients. The percentage of recent thymic emigrants (RTE) used to stratify fingolimod responder, and no responder patients was the best biomarker (4.0 ± 1.4% vs 7.4 ± 1.9%, respectively [P < 0.001]). CONCLUSION: The results support that immune-monitoring of lymphocyte subpopulations in peripheral blood is a promising tool to select RRMS candidate for fingolimod treatment.

Monitoring T-Cell Responses in Translational Studies: Optimization of Dye-Based Proliferation Assay for Evaluation of Antigen-Specific Responses.

Adoptive therapy with regulatory T cells or tolerance-inducing antigen (Ag)-presenting cells is innovative and promising therapeutic approach to control undesired and harmful activation of the immune system, as observed in autoimmune diseases, solid organ and bone marrow transplantation. One of the critical issues to elucidate the mechanisms responsible for success or failure of these therapies and define the specificity of the therapy is the evaluation of the Ag-specific T-cell responses. Several efforts have been made to develop suitable and reproducible assays. Here, we focus on dye-based proliferation assays. We highlight with practical examples the fundamental issues to take into consideration for implementation of an effective and sensitive dye-based proliferation assay to monitor Ag-specific responses in patients. The most critical points were used to design a road map to set up and analyze the optimal assay to assess Ag-specific T-cell responses in patients undergoing different treatments. This is the first step to optimize monitoring of tolerance induction, allowing comparison of outcomes of different clinical studies. The road map can also be applied to other therapeutic interventions, not limited to tolerance induction therapies, in which Ag-specific T-cell responses are relevant such as vaccination approaches and cancer immunotherapy.