Soluble Antigen Array Displaying Proinsulin(F25D) Selectively Targets Anti-insulin B Cells without Hormonal Effects

Antigen presentation to autoreactive T cells in the pancreatic islets by dendritic cells and B lymphocytes is paramount to the pathogenesis of Type 1 diabetes (T1D). Immunosuppressive therapies, such as rituximab (anti-CD20) and teplizumab (anti-CD3), can delay T1D onset; however, risks associated with B or T cell depletion, such as an increased susceptibility to infections, are considerable. Antigen-specific immunotherapy (ASIT) offers a more targeted approach to suppress or delete the autoreactive cells, specifically recognizing autoantigens associated with disease. Soluble antigen arrays (SAgAs) are a platform consisting of a hyaluronic acid (HA) backbone and multiple copies of the autoantigen to selectively suppress autoreactive B cells and T cells. Here, a new SAgA was developed by conjugating a mutated proinsulin antigen (proinsulin(F25D)) to HA (SAgA M-PI(F25D) ) to avoid glycemic activity while retaining the ability to target anti-insulin antibodies and B cells. SAgA M-PI(F25D) had a pronounced reduction in insulin receptor-β activity and lacked glycemic activity in vivo . Furthermore, this SAgA successfully bound a disease-relevant monoclonal anti-insulin antibody with low nanomolar binding affinity and murine transgenic (Tg125) B cells specific for human insulin. This collection of data demonstrated the avoidance of glycemic effects of proinsulin SAgAs while retaining specificity to anti-insulin antibody and insulin-binding B cells, thus highlighting the potential as a candidate for intervening in T1D as an ASIT.