Proinsulin multi-peptide immunotherapy induces antigen-specific regulatory T cells and limits autoimmunity in a humanized model

Abstract

SummaryPeptide immunotherapy (PIT) is a targeted therapeutic approach, involving administration of disease-associated peptides, with the aim of restoring antigen-specific immunological tolerance without generalized immunosuppression. In type 1 diabetes, proinsulin is a primary antigen targeted by the autoimmune response, and is therefore a strong candidate for exploitation via PIT in this setting. To elucidate the optimal conditions for proinsulin-based PIT and explore mechanisms of action, we developed a preclinical model of proinsulin autoimmunity in a humanized HLA-DRB1*0401 transgenic HLA-DR4 Tg mouse. Once proinsulin-specific tolerance is broken, HLA-DR4 Tg mice develop autoinflammatory responses, including proinsulin-specific T cell proliferation, interferon (IFN)-g and autoantibody production. These are preventable and quenchable by pre-and post-induction treatment, respectively, using intradermal proinsulin-PIT injections. Intradermal proinsulin-PIT enhances proliferation of regulatory [forkhead box protein 3 (FoxP3T cells, including those capable of proinsulin-specific regulation, suggesting this as its main mode of action. In contrast, peptide delivered intradermally on the surface of vitamin D3-modulated (tolerogenic) dendritic cells, controls autoimmunity in association with proinsulin-specific IL-10 production, but no change in regulatory CD4 T cells. These studies define a humanized, translational model for in vivo optimization of PIT to control autoimmunity in type 1 diabetes and indicate that dominant mechanisms of action differ according to mode of peptide delivery.

The induction of autoimmune hepatitis in the human leucocyte antigen-DR4 non-obese diabetic mice autoimmune hepatitis mouse model

“…A similar phenomenon has been seen in other types of autoimmune liver diseases, including a primary biliary cirrhosis (PBC)‐like pathology mediated by B lymphocytes and autoimmune cholangitis . DR4 transgenic mice have been used for other autoimmune disease models, such as type 1 diabetes and rheumatoid arthritis , although not on a NOD genetic background.…”

“…More relevant to the current study is that HLA‐DR4 molecules play an important role in developing autoantigen‐specific immunotherapy, demonstrated by Gibson et al . that immunization with autoantigen alone or with autoantigen‐loaded tolerogenic DCs can induce antigen‐specific tolerance in HLA‐DR4 Tg mice for type 1 diabetes (T1D) . More recently, it has been shown by Clemente‐Casares and colleagues that disease‐specific autoantigens can be administered as complexes in which antigenic peptides bound to MHC class II molecules (pMHC‐II) are coated on nanoparticles.…”

Regulatory T cell dysfunction in type 1 diabetes: what’s broken and how can we fix it?

“…In animal models of type 1 diabetes, administration of islet autoantigen using a variety of tolerogenic regimens has provided protection against islet destruction, which is often associated with an increase in IL-10 production by CD4 + T cells, although in many cases the regulatory potential of these cells is not well understood [ 84 – 86 ]. More recently, in a humanised HLA-transgenic mouse model of islet autoimmunity, Gibson and colleagues demonstrated that, while peptide presented by tolerogenic dendritic cells controlled autoimmunity and was associated with islet-specific IL-10 production, intradermal injection of the same peptide also reduced autoimmunity and increased the proliferation of FOXP3 + Tregs [ 87 ]. This elegantly demonstrates that the route and method of delivery of an antigen-specific immunotherapy can influence the mechanism by which it may afford protection.…”

Human islets and dendritic cells generate post-translationally modified islet autoantigens

“…Furthermore, we observed that inflammation is a trigger for increased tTG activity in islets and DC. If DC bear the capacity to target autoreactive T cells specific for both native and deamidated islet epitopes it could add significant value to current peptide immunotherapy strategies [15,16] by increasing vaccine efficacy and simplifying vaccine design.…”