Modular Peptide Amphiphile Micelles Improve an Antibody-Mediated Immune Response to Group A Streptococcus John C. Barrett, Bret D. Ulery, Amanda Trent, Simon Liang, Natalie David, Matthew V. Tirrell. Institute for Molecular Engineering, University of Chicago; Department of Chemical Engineering, University of Missouri; Biomolecular Science and Engineering Program, UCSB; Division of Biological Sciences, University of Chicago. Statement of Purpose: stay at the injection site any longer than its free peptide Peptide amphiphiles (PAs) are a class of peptide-based counterpart. Since no in vivo accumulation could be seen biomaterials consisting of bioactive peptide head groups from the whole mouse imaging, draining lymph nodes conjugated to hydrophobic alkyl tails which self-assemble were imaged to assess the trafficking potential of each in aqueous solution into micellar structures. In our formulation. At 12h, the micelle formulation showed previous studies, peptide amphiphile micelles (PAMs) significantly greater fluorescence in both sets of draining were used as a vaccine delivery vehicle that induced a lymph nodes than in either the PBS or free peptide peptide-specific antibody response. Interestingly, PAMs formulation. Therefore, even though both vaccine stimulated a stronger antibody response than peptide formulations seemed to clear from the injection site at the alone without the use of an adjuvant. Self-assembly of same rate, micelles cleared to the lymph nodes more PAs has the added benefit of being able to facilitate the efficiently than free peptides. Heterogeneous micelles fabrication of multifunctional heterogeneous micelles mixed with amphiphilic adjuvants such as MPLA and through simple mixing of different PAs or other P2C were successfully made. The ability of amphiphilic molecules. Specifically, the incorporation of heterogeneous micelles to enhance antibody titers was secondary molecular signals or amphiphilic adjuvants has assessed. As shown in Figure 1 below, the addition of the capacity to yield more robust host immune responses. either MPLA or P2C-SK4 to J8-diC16 micelles stimulates Nanoparticle physical characteristics including size and the production of higher antibody titers with fewer doses shape have been found to influence immune responses as when compared to the pure J8 micelles alone and the well as in vivo biodistribution and clearance. Antigenic soluble J8 peptide in IFA. Finally, confocal images PAs previously used for vaccine applications self- showing that antibodies from immunized mice are assemble into long, flexible cylindrical micelles capable of binding to wild-type GAS but not to mutant approximately 5−15 nm in diameter and 200 nm to 2 µm GAS lacking surface expression of M1 protein. in length, after annealing. Recognizing that no universal rules exist that can be applied to predict the in vivo behavior of all nanoparticles, it is important that the biodistribution and clearance of nanomaterials be evaluated for each new structure. Given the unique properties of this system and its inherent modularity, understanding biodistribution and clearance profiles can help to further elucidate micelle mechanisms of adjuvanticity and inform the rational design of micelles for vaccination applications. This presentation explores the potential of peptide amphiphile micelles to serve as a Figure 1. Mixed peptide amphiphile micelles induced modular immunotherapeutic platform. strong antibody response in vivo Methods: Biomaterials were synthesized using standard Conclusions: This research expands upon the micelle Fmoc SPPS and orthogonal conjugation chemistries. vaccine concept and demonstrates how peptide Micelles were characterized by CMC and TEM. In order amphiphile modularity can be utilized to improve to investigate biodistribution, BALB/c mice were corresponding responses. It was revealed that micelle immunized with fluorescent micelles. Whole live animal formulations cleared from the injection site at a similar and animal organs were imaged at multiple time points rate to the soluble J8 peptide but trafficked to the lymph using an IVIS 200. Mice were also used to investigate the node more efficiently than soluble peptide. The capacity for various micelle formulations to induce an amphiphilic and modular nature of peptide amphiphiles antibody mediated immune response. Finally, wild type enabled the precise addition of amphiphilic adjuvants, and ∆emm GAS were used to investigate the ability of which did not disrupt the formation of cylindrical raised antibodies to bind to M1 protein on GAS. micelles. When delivered subcutaneously to mice, Results: Biodistribution of micelle vs. free peptide was heterogeneous micelles induced a stronger IgG antibody investigated using fluorescently labeled peptides. When response than seen with a conventional gold-standard comparing the speed with which the fluorescent signal vaccine formulation. These experiments taken together cleared from the injection site, both formulations cleared provide convincing evidence that heterogeneous micelles at essentially the same magnitude, approximately a few can enhance lymph node codelivery of antigens and hours. On the basis of this size profile and data from other adjuvants leading to the dramatically improved antibody nanoparticle platforms, it was hypothesized that the response observed. micelles would get trapped in the interstitial space and act References: Barrett JC. ACS Biomat. Sci. and Eng. as an antigen depot. On the basis of the live whole animal 2016; Article ASAP. imaging data, however, it appears that micelles do not