Poster Session - Abstract # 5

Low valency Insulin-CD22 Ligand Conjugates Reduce Insulin-specific B Cell Activation in Response to Anti-CD40 Stimulation

Kyle Apley^1*, Amber Griffith^2*, Grant Downes³, Patrick Ross4, Mark Farrell⁴, Peggy L. Kendall², and Cory Berkland^1,3,5

¹Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, USA; ²Department of Allergy and Immunology, Washington University, St. Louis, MO, USA; ³Bioengineering Graduate Program, University of Kansas, Lawrence, KS, USA; ⁴Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA; ⁵Department of Chemical & Petroleum Engineering, University of Kansas, Lawrence, KS, USA
*Both contributed equally

Therapeutic measures for effectively treating autoimmune diseases primarily result in global immune system suppression giving rise to several health complications for autoimmune patients.  Antigen-specific immunotherapies (ASIT) are a precise method of hindering autoreactive immune cells while diminishing the risk for undesired symptoms or disease states.  Antigen arrays have been employed in ASITs to enable the effective delivery of antigenic peptides or proteins in a multivalent fashion.  Herein, we have designed an antigen array consisting of a 4-arm PEG backbone with varying ratios of insulin (antigen) and CD22 ligand conjugated using CuAAC click chemistry to target insulin-specific B cells that contribute to disease in type 1 diabetes.  Whereas common formulations of multivalent antigen arrays are comprised solely of antigens only and have a poorly defined tolerogenic mechanism, the combined antigen-CD22L format aims to trigger a unique B cell pathway to prevent B cell activation.  Monovalent insulin-mCD22L direct conjugates were compared to multivalent insulin-mCD22L antigen arrays to validate and quantify the significant advantage of a multivalent approach.  These constructs blunt B cell activation upon co-incubation with anti-insulin B cells stimulated by anti-CD40, however, they are rendered ineffective in deterring B cell activation stimulated by CpG demonstrated in proliferation assays and flow cytometry. In conjunction, multimeric 4-arm PEG-insulin/mCD22L demonstrate effective targeting and dampening of anti-insulin B cell proliferation which further amplifies the potential of multimeric antigen arrays as an effective ASIT for type one diabetes.  Furthermore, these antigen-CD22L conjugates shine a new lens on multivalent systems as other established multivalent antigen-CD22L systems are very large and complex.  This data suggests that discrete, low valency systems are indeed effective in blocking B-cell activation using BCR-CD22L co-localization lending itself toward translation and technological advances in combating autoimmunity.