Multimeric Insulin Desensitizes Insulin-Specific B Cells

Adaptive immunity plays a central role in the pathogenesis of type 1 diabetes. Among past treatment approaches, B cell ablation has yielded unmistakable therapeutic potency; however, global immunosuppression imposes unacceptable risks to a patient population consisting of children. Multivalent antigen arrays represent a compelling strategy for targeted immunosuppression by selectively engaging and inactivating autoreactive B cells. Here, we report the design and characterization of 4-arm polyethylene glycol-insulin (PEG-Ins) conjugates as multivalent arrays for autoreactive B cell engagement. First, we selectively modified human insulin at the B29 residue to retain antigenicity. Next, we conjugated the modified proteins to 20 kDa, 4-arm polyethylene glycol backbones to produce multivalent PEG-Ins constructs. Mass spectrometry, circular dichroism, and dynamic light scattering indicated that the structure of insulin was maintained in the much larger, multivalent construct. PEG-Ins conjugates demonstrated an ex vivo immunological effect in splenocytes harboring an anti-insulin B cell receptor (VH125SD) by inactivating B cells and promoting an anergic phenotype that was downregulated in B cell receptor expression (CD79b), and PEG-Ins conjugates did not mobilize calcium upon B cell receptor stimulation. These data support the further study of PEG-Ins conjugates in animal models of type 1 diabetes.