Antigen-Specific Binding of Multivalent Soluble Antigen Arrays Induces Receptor Clustering and Impedes B Cell Receptor Mediated Signaling

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• 作者：Brittany L. Hartwell ; Francisco J. Martinez-Becerra ; Jun Chen ; Heather Shinogle ; Michelle Sarnowski ; David S. Moore ; Cory Berkland
• 刊名：Biomacromolecules
• 出版年：2016
• 出版时间：March 14, 2016
• 年：2016
• 卷：17
• 期：3
• 页码：710-722
• 全文大小：837K
• ISSN：1526-4602

文摘

A pressing need exists for autoimmune disease therapies that act in an antigen-specific manner while avoiding global immunosuppression. Multivalent soluble antigen arrays (SAgA_PLP:LABL), designed to induce tolerance to a specific multiple sclerosis autoantigen, consist of a flexible hyaluronic acid (HA) polymer backbone cografted with multiple copies of autoantigen peptide (PLP) and cell adhesion inhibitor peptide (LABL). Previous in vivo studies revealed copresentation of both signals on HA was necessary for therapeutic efficacy. To elucidate therapeutic cellular mechanisms, in vitro studies were performed in a model B cell system to evaluate binding and specificity. Compared to HA and HA arrays containing only grafted PLP or LABL, SAgA_PLP:LABL displaying both PLP and LABL exhibited greatly enhanced B cell binding. Furthermore, the binding avidity of SAgA_PLP:LABL was primarily driven by the PLP antigen, determined via flow cytometry competitive dissociation studies. Fluorescence microscopy showed SAgA_PLP:LABL induced mature receptor clustering that was faster than other HA arrays with only one type of grafted peptide. SAgA_PLP:LABL molecules also reduced and inhibited IgM-stimulated signaling as discerned by a calcium flux assay. The molecular mechanisms of enhanced antigen-specific binding, mature receptor clustering, and dampened signaling observed in B cells may contribute to SAgA_PLP:LABL therapeutic efficacy.