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For almost a hundred years, the management of Type 1 diabetes has not advanced beyond insulin replacement. However, insulin does not provide satisfactory glycaemic control in the majority of individuals and there remains a major unmet need for novel treatments for Type 1 diabetes. Immunomodulation to preserve beta-cell function offers the prospect of making treatment with insulin easier and/or preventing the need for insulin, particularly when it comes to novel low-risk immunotherapies. Led by the concept that the best insulin-producing cell is a patient's own beta-cell, the Type 1 diabetes scientific community has a challenging task ahead-to fundamentally change the management of this devastating disease by using low-risk immunotherapy to preserve endogenous beta-cell function and make metabolic control substantially easier. In that way, insulin and/or beta-cell replacement (stem cell or transplantation) should in the future be considered rescue therapies reserved for delayed presentations., (© 2021 Diabetes UK.)

Antigen specific immunotherapy aims to tolerise patients to specific autoantigens that are responsible for the pathology of an autoimmune disease. Immune tolerance is generated in conditions where the immune response is suppressed and thus gold nanoparticles (AuNPs) are an attractive drug delivery platform due to their anti-inflammatory effects and their potential to facilitate temporal and spatial delivery of a peptide autoantigen in conjunction with pro-tolerogenic elements. In this study we have covalently attached an autoantigen, currently under clinical evaluation for the treatment of type 1 diabetes (PI C19-A3 peptide), to AuNPs to create nanoscale (<5 nm), negatively charged (-40 to -60 mV) AuNP-peptide complexes for immunotherapy. We also employ a clinically approved microneedle delivery system, MicronJet600, to facilitate minimally-invasive intradermal delivery of the nanoparticle constructs to target skin-resident antigen presenting cells, which are known to be apposite target cells for immunotherapy. The AuNP-peptide complexes remain physically stable upon extrusion through microneedles and when delivered into ex vivo human skin they are able to diffuse rapidly and widely throughout the dermis (their site of deposition) and, perhaps more surprisingly, the overlying epidermal layer. Intracellular uptake was extensive, with Langerhans cells proving to be the most efficient cells at internalising the AuNP-peptide complex (94% of the local population within the treated region of skin). In vitro studies showed that uptake of the AuNP-peptide complexes by dendritic cells reduced the capacity of these cells to activate naïve T cells. This indicator of biological functionality encourages further development of the AuNP-peptide formulation, which is now being evaluated in clinical trials., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Immunotherapy using short immunogenic peptides of disease-related autoantigens restores immune tolerance in preclinical disease models. We studied safety and mechanistic effects of injecting human leukocyte antigen-DR4( DRB1*0401 )-restricted immunodominant proinsulin peptide intradermally every 2 or 4 weeks for 6 months in newly diagnosed type 1 diabetes patients. Treatment was well tolerated with no systemic or local hypersensitivity. Placebo subjects showed a significant decline in stimulated C-peptide (measuring insulin reserve) at 3, 6, 9, and 12 months versus baseline, whereas no significant change was seen in the 4-weekly peptide group at these time points or the 2-weekly group at 3, 6, and 9 months. The placebo group's daily insulin use increased by 50% over 12 months but remained unchanged in the intervention groups. C-peptide retention in treated subjects was associated with proinsulin-stimulated interleukin-10 production, increased FoxP3 expression by regulatory T cells, low baseline levels of activated β cell-specific CD8 T cells, and favorable β cell stress markers (proinsulin/C-peptide ratio). Thus, proinsulin peptide immunotherapy is safe, does not accelerate decline in β cell function, and is associated with antigen-specific and nonspecific immune modulation., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Antigen specific immunotherapy mediated via the sustained generation of regulatory T cells arguably represents the ideal therapeutic approach to preventing beta cell destruction in type 1 diabetes. However, there is a need to enhance the efficacy of this approach to achieve disease modification in man. Previous studies suggest that prolonged expression of self-antigen in skin in a non-inflammatory context is beneficial for tolerance induction. We therefore sought to develop a dry-coated microneedle (MN) delivery system and combine it with topical steroid to minimise local inflammation and promote prolonged antigen presentation in the skin. Here we show that a combination of surface-modified MNs coated with appropriate solvent systems can deliver therapeutically relevant quantities of peptide to mouse and human skin even with hydrophobic peptides. Compared to conventional "wet" intradermal (ID) administration, "dry" peptide delivered via MNs was retained for longer in the skin and whilst topical hydration of the skin with vehicle or steroid accelerated loss of ID-delivered peptide from the skin, MN delivery of peptide was unaffected. Furthermore, MN delivery resulted in enhanced presentation of antigen to T cells in skin draining lymph nodes (LNs) both 3 and 10days after administration. Repeated administration of islet antigen peptide via MN was effective at reducing antigen-specific T cell proliferation in the pancreatic LN, although topical steroid therapy did not enhance this. Taken together, these data show auto-antigenic peptide delivery into skin using coated MNs results in prolonged retention and enhanced antigen presentation compared to conventional ID delivery and this approach may have potential in individuals identified as being at a high risk of developing type 1 diabetes and other autoimmune diseases., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)