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AIM/HYPOTHESIS: Combination therapy targeting the major actors involved in the immune-mediated destruction of pancreatic beta cells appears to be an indispensable approach to treat type 1 diabetes effectively. We hypothesised that the combination of an orally active pan-histone deacetylase inhibitor (HDACi: givinostat) with subtherapeutic doses of CD3 antibodies may provide ideal synergy to treat ongoing autoimmunity. METHODS: NOD mice transgenic for the human CD3ε (also known as CD3E) chain (NOD-huCD3ε) were treated for recent-onset diabetes with oral givinostat, subtherapeutic doses of humanised CD3 antibodies (otelixizumab, 50 µg/day, 5 days, i.v.) or a combination of both drugs. Disease remission, metabolic profiles and autoreactive T cell responses were analysed in treated mice. RESULTS: We demonstrated that givinostat synergised with otelixizumab to induce durable remission of diabetes in 80% of recently diabetic NOD-huCD3ε mice. Remission was obtained in only 47% of mice treated with otelixizumab alone. Oral givinostat monotherapy did not reverse established diabetes but reduced the in situ production of inflammatory cytokines (IL-1ß, IL-6, TNF-α). Importantly, the otelixizumab + givinostat combination strongly improved the metabolic status of NOD-huCD3ε mice; the mice recovered the capacity to appropriately produce insulin, control hyperglycaemia and sustain glucose tolerance. Finally, diabetes remission induced by the combination therapy was associated with a significant reduction of insulitis and autoantigen-specific CD8+ T cell responses. CONCLUSIONS/INTERPRETATION: HDACi and low-dose CD3 antibodies synergised to abrogate in situ inflammation and thereby improved pancreatic beta cell survival and metabolic function leading to long-lasting diabetes remission. These results support the therapeutic potential of protocols combining these two drugs, both in clinical development, to restore self-tolerance and insulin independence in type 1 diabetes.

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Objective Cytotoxic T lymphocytes are the main effector cells of anti-tumor immunity. Active targeting of nanoparticles to T cells and activation of T cells can be achieved by conjugation with specific antibodies. We prepared the biotin-grafted pullulan acetate nanoparticles conjugated with CD3 (Bio-PA-CD3 NPs), and explored their effects on the proliferation, cytokine secretion and uptake of CD8+T cells.Methods We prepared Bio-PA NPs by the dialysis method, conjugated CD3 antibodies to the surface of NPs to make Bio-PA-CD3 NPs, and measured the diameter and Zeta potential of the NPs. We evaluated the effects of the NPs on the proliferation of CD8+T cells and the secretion of cytokines by CCK-8 assay and ELISA, respectively, and quantitatively analyzed the cellular uptakes of the Bio-PA-CD3 NPs by the flow cytometry.Results The Bio-PA-CD3 NPs exhibited regular spherical shapes of even size and with no adhesion. The content of CD3 antibodies on the surface of the NPs decreased with the increased degree of biotin substitution. The CD3 contents of the Bio-PA-CD3 NPs with biotin substitution degrees of 1.6%, 5.4% and 6.3% were (36.1±4.4), (21.4±4.3) and (10.3±4.7) μg/mg, respectively. Compared with Bio-PA NPs, Bio-PA-CD3 NPs at a certain concentration significantly enhanced the proliferation of CD8+T cells in vitro and promoted the secretion of IFN-γ, TNF-β and IL-2 cytokines. The Bio-PA-CD3 NPs manifested a higher cellular uptake with the increased content of CD3 antibodies.Conclusion The Bio-PA-CD3 NPs we prepared could be a promising agent to enhance the immune effect of T cells.

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The induction of tolerance is a major goal of immunotherapy. Investigations over the last 20 years have shown that anti-CD3 monoclonal antibodies (mAbs) effectively treat autoimmune disease in animal models and have also shown promise in clinical trials. Tolerance induction by anti-CD3 mAbs is related to the induction of Tregs that control pathogenic autoimmune responses. Here, we review preclinical and clinical studies in which intravenous or mucosal administration of anti-CD3 mAbs has been employed and provide an outlook on future developments to enhance the efficacy of this promising therapeutic approach.

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In this brief review we propose to discuss salient data showing the importance of immune regulatory mechanisms, and in particular of Treg, for the control of pathogenic anti-ß-cell response in autoimmune diabetes. Disease progression that culminates with the massive destruction of insulin-secreting ß-cells and advent of hyperglycemia and glycosuria tightly correlates with a functional deficit in immune regulation. Better dissection of the cellular and molecular mechanisms through which the immune system normally sustains tolerance to "self", and which become defective when autoimmune aggression is overt, is the only direct and robust way to learn how to harness these effectively, so as to restore immune tolerance in patients with insulin-dependent type 1 diabetes. No doubt that regulatory T cells are a privileged mechanism underlying this self-tolerance in the periphery. The discovery of the key role of the transcription factor FoxP3, represented the cornerstone leading to the great advances in the field we are witnessing today. Type 1 diabetes is certainly one of the prototypic T cell-mediated autoimmune diseases where immune regulatory mechanisms relying on specialized subsets of T cells have been the most thoroughly analyzed from the fundamental point of view and also largely exploited in a translational therapeutic perspective.

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