Self-assembling synthetic nanoadjuvant scaffolds cross-link B cell receptors and represent new platform technology for therapeutic antibody production

Abstract

Host antibody responses are pivotal for providing protection against infectious agents. We have pioneered a new class of self-assembling micelles based on pentablock copolymers that enhance antibody responses while providing a low inflammatory environment compared to traditional adjuvants. This type of “just-right” immune response is critical in the rational design of vaccines for older adults. Here, we report on the mechanism of enhancement of antibody responses by pentablock copolymer micelles, which act as scaffolds for antigen presentation to B cells and cross-link B cell receptors, unlike other micelle-forming synthetic block copolymers. We exploited this unique mechanism and developed these scaffolds as a platform technology to produce antibodies in vitro. We show that this novel approach can be used to generate laboratory-scale quantities of therapeutic antibodies against multiple antigens, including those associated with SARS-CoV-2 and Yersinia pestis, further expanding the value of these nanomaterials to rapidly develop countermeasures against infectious diseases.

Structural Stability and Antigenicity of Universal Equine H3N8 Hemagglutinin Trimer upon Release from Polyanhydride Nanoparticles and Pentablock Copolymer Hydrogels

“…Significantly, visualization of the protein structure by native PAGE gels found partial disruption of the trimer into dimers and monomers. This is to be expected, given the assembly of the trimer by charge association and the cationic nature of PBCs, but is a worthwhile tradeoff with the antigenic scaffolding and B-cell receptor cross-linking provided by PBCs. , Furthermore, the lack of additional bands at lower molecular weights (<66 kDa) supports the finding that the primary structure of monomeric HA 0 was maintained without degradation into HA 1 and HA 2 subunits. − …”

“…The average micelle size in the PBC aqueous solution was 20 ± 4.41 nm with a ζ potential of 10.9 ± 1.78 mV, determined by dynamic light scattering, and these data were consistent with previous work (Table 1). 28 Antigen release kinetics from the polyanhydride nanoparticles were measured for approximately 1 month (Figure 1A). The initial burst release (i.e., within the first day) was relatively small and followed by a sustained, near-zero order release of rH3 3 .…”

“…This is to be expected, given the assembly of the trimer by charge association and the cationic nature of PBCs, but is a worthwhile tradeoff with the antigenic scaffolding and B-cell receptor cross-linking provided by PBCs. 17,28 Furthermore, the lack of additional bands at lower molecular weights (<66 kDa) supports the finding that the primary structure of monomeric HA 0 was maintained without degradation into HA 1 and HA 2 subunits. 32−34 To establish the antigenicity of the released rH3 3 antigen, an ELISA was performed on the released rH3 3 antigen from the nanoparticles, utilizing sera from infected horses and immunized ferrets and mice (Figure 4A).…”

A Polylactide-Based Micellar Adjuvant Improves the Intensity and Quality of Immune Response

“…Regarding the quality of the immune response, the micelles induced Abs with a high avidity compared to the gold standards and were again similar to that of 160 nm-PLA NP. One hypothetical explanation of this strong humoral response with high avidity could be related to the B Cell Receptor (BCR) engagement due to the biodistribution profile of micelles through the draining lymph system, favoring a BCR clustering, as it has been observed with other self-assembled micelles [47,48] and NP [49,50]. To date, to our knowledge, no micellar-based system has shown a performance that can compete with vaccine gold standards (alum and MF59) by means of both intensity and quality of humoral immune response.…”

Lipid Membrane‐Based Antigen Presentation to B Cells Using a Fully Synthetic Ex Vivo Germinal Center Model

“…[ 21 ] Recent work has shown that lipid‐based particle systems can potentially cross‐link BCRs. [ 22–24 ] However, there has not been evidence of the generation of GC‐like B cells or class‐switch recombination in these in vitro lipid‐based systems, suggesting a potential extrafollicular B cell maturation process, which is a short‐lived, low‐affinity response. Here, we engineered liposomes to mimic FDC membrane fragments to activate B cells in vitro (Figure 1C), and demonstrate rapid B cell proliferation, efficient induction of the GC reaction, and IgG1 class‐switching.…”