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Biomaterials

Biomaterials - Poster Session E

Poster O6 - Lipopeptide-based hydrogel possesses immune-modulating adjuvant-like properties for the delivery of the GPC-3 peptide-derived antigen

Saturday, October 26, 2024
10:00 AM – 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Vaccinations are a monumental achievement in public health and biomedical research. Recently, interest has surged in using vaccines for therapeutic cancer treatment, yet only three FDA-approved therapeutic cancer vaccines exist. Peptide-based cancer vaccines are promising due to their ability to elicit antigen-specific T-cells and their safety profile. Despite this, their poor immunogenicity necessitates a robust adjuvant to enhance their efficacy. Adjuvants are crucial in vaccines as they stimulate innate immune pathways, enhancing antigen presentation and promoting APC activation and maturation. Successful cancer vaccine adjuvants need to prolong antigen exposure and upregulate costimulatory molecules on APCs. Only nine adjuvants are approved in the U.S. and Europe, with traditional adjuvants like aluminum salts being ineffective for peptide-based vaccines. Mechanistically, some adjuvants mimic pathogen-associated molecular pathways to activate desired immune responses. Lipopeptide-based adjuvants, such as Pam3CSK4, are TLR agonists but lack peptide antigen carrier functions. Novel adjuvants that minimize side effects, elicit strong immune responses, and serve as carriers are in demand. Peptide-based supramolecular hydrogels are emerging as potential adjuvant platforms due to their self-assembling capabilities and immunomodulatory properties. This study investigates novel lipopeptide hydrogels (LPHs) with adjuvant-like properties for delivering a cancer immunogen, aiming to enhance the efficacy of cancer vaccinations.

Materials and

Methods:  This study investigated the formulation and evaluation of lipopeptide hydrogels (LPHs) as adjuvant-like platforms for cancer vaccines. The LPHs were synthesized by conjugating myristic acid (Myr) to diphenylalanine (FF) and FF with tyrosine (Y), forming Myr-FF, Myr-FFY, and a combination gel (Cogel). The self-assembly of these compounds into LPHs was characterized through microscopy and spectroscopy techniques, confirming their nanofibrous network structure. The hydrogels' injectability and entrapment capabilities were assessed based on their rheological properties. The ability of LPHs to sustain the release of the HLA-A02 GPC-3 derived peptide, an immunogen overexpressed in hepatocellular carcinoma (HCC) cells, was evaluated using in vitro release studies using fluorescence microscopy. The uptake of the released peptide by antigen-presenting cells (APCs) was examined through flow cytometry. To determine the adjuvant-like properties of LPHs, their capacity to stimulate Toll-like receptor 2 (TLR2) activity was measured using HEK-BLUE SEAP assays. Additionally, the expression of costimulatory molecules (CD80/86) on APCs was quantified using flow cytometry. The immunogenic response was further analyzed by measuring the production of pro-inflammatory cytokines IL-6 and TNF-α using ELISA. In vivo studies involved injecting LPHs into mice and monitoring for any notable changes in weight or primary organs. Inflammation in lymph nodes was observed as an indicator of immune cell infiltration.

Results, Conclusions, and Discussions: The study successfully engineered three novel lipopeptide hydrogels (LPHs)—Myr-FF, Myr-FFY, and Cogel—with adjuvant-like immunomodulating properties for cancer immunogen delivery. The self-assembled LPHs exhibited nanofibrous networks confirmed through microscopy and spectroscopy, demonstrating suitable rheological properties for injection due to their shear-thinning and self-healing characteristics. The HLA-A02 GPC-3 derived peptide was released from the LPHs in a sustained manner over two weeks, facilitating effective uptake by antigen-presenting cells (APCs). LPHs significantly stimulated TLR2 activity, as evidenced by increased HEK-BLUE SEAP activity and upregulated CD80/86 expression on APCs. The presence of tyrosine in Myr-FFY and Cogel contributed to a robust immune response, indicated by elevated levels of pro-inflammatory cytokines IL-6 and TNF-α, compared to Myr-FF and iDCs. In vivo studies showed no adverse effects on weight or primary organs, suggesting LPHs' safety, though increased lymph node inflammation indicated immune cell infiltration. These findings highlight LPHs' potential as adjuvant-like platforms, providing prolonged antigen exposure and enhanced APC activation, crucial for effective cancer vaccines. Overall, this study advances the development of safer, more effective cancer vaccine adjuvants, with potential applicability to multiple cancer types through antigen substitution.

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