Therapeutic Antibodies to Ganglioside GD2 Evolved from Highly Selective Germline Antibodies

Abstract

Summary Antibodies play a crucial role in host defense and are indispensable research tools, diagnostics, and therapeutics. Antibody generation involves binding of genomically encoded germline antibodies followed by somatic hypermutation and in vivo selection to obtain antibodies with high affinity and selectivity. Understanding this process is critical for developing monoclonal antibodies, designing effective vaccines, and understanding autoantibody formation. Prior studies have found that antibodies to haptens, peptides, and proteins evolve from polyspecific germline antibodies. The immunological evolution of antibodies to mammalian glycans has not been studied. Using glycan microarrays, protein microarrays, cell binding studies, and molecular modeling, we demonstrate that therapeutic antibodies to the tumor-associated ganglioside GD2 evolved from highly specific germline precursors. The results have important implications for developing vaccines and monoclonal antibodies that target carbohydrate antigens. In addition, they demonstrate an alternative pathway for antibody evolution within the immune system that is distinct from the polyspecific germline pathway.

Repertoire Analysis of Antibody CDR-H3 Loops Suggests Affinity Maturation Does Not Typically Result in Rigidification

“…The MD simulations and subsequent analyses suggested that multi-specific antigen binding is mediated by a combined mechanism of conformer selection and induced fit. Similar behavior, where the mature antibody is more flexible than the naïve has been observed for an antibody that recognizes the tumor-associated ganglioside GD2 ( 79 ). Such antibodies could not have arisen if CDR-H3 loop rigidification were a consistent result of affinity maturation.…”

Activated NF-κB/Nrf2 and Wnt/β-catenin pathways are associated with lipid metabolism in CKD patients with microalbuminuria and macroalbuminuria

“…Ganglioside is a component of cell membrane that plays a critical role in the modulation of signal transduction [62,63]. Gangliosides amount to approximately 6% of the weight of lipids in brain, but gangliosides are found in all animal tissues [64]. A lot of gangliosides were firstly identified from the serum of CKD patients with albuminuria in our study, among which ganglioside GD3 (d18:1/26:0) and ganglioside GD2 (d18:1/18:0) were used to distinguish CKD patients with microalbuminuria from healthy controls as well as CKD patients with microalbuminuria and macroalbuminuria, respectively.…”

Insights into the Structural Basis of Antibody Affinity Maturation from Next-Generation Sequencing

“…As described earlier, studies of immune responses to haptens, model proteins, and HIV-1 Env have shown that affinity maturation generates antibodies with higher affinity and specificity than germ line antibodies, at least in part through rigidification of the paratope. However, a recent study of glycan-specific antibodies has suggested an alternative pathway for antibody evolution that is distinct from the polyreactive germ line pathway ( 55 ).…”

“…A combination of glycan microarrays and molecular dynamics (MD) simulations was used to investigate the affinity maturation of two antibodies (3F8 and ch14.18) specific for the ganglioside GD2, a tumor-associated carbohydrate antigen overexpressed in various cancers, notably neuroblastoma and melanoma ( 55 ). Surprisingly, the putative germ line antibodies, although of lower affinity than their matured counterparts, were just as highly selective for CD2 as the matured antibodies when screened against hundreds of glycans and thousands of proteins.…”

“…Surprisingly, the putative germ line antibodies, although of lower affinity than their matured counterparts, were just as highly selective for CD2 as the matured antibodies when screened against hundreds of glycans and thousands of proteins. Possible reasons for this lack of observable polyreactivity were investigated by MD simulations of germ line and affinity-matured 3F8 and ch14.18 ( 55 ). These simulations revealed that, rather than becoming more rigid, the binding sites of the matured anti-G2 antibodies showed an increase in flexibility relative to the binding sites of the germ line antibodies.…”