Synthesis of a Liposomal MUC1 Glycopeptide-Based Immunotherapeutic and Evaluation of the Effect of l-Rhamnose Targeting on Cellular Immune Responses

Abstract

Generation of a CD8+ response to extracellular antigen requires processing of the antigen by antigen presenting cells (APC) and cross-presentation to CD8+ T cell receptors via MHC class I molecules. Cross-presentation is facilitated by efficient antigen uptake followed by immune-complex-mediated maturation of the APCs. We hypothesize that improved antigen uptake of a glycopeptide sequence containing a CD8+ T cell epitope could be achieved by delivering it on a liposome surface decorated with an immune complex-targeting ligand, an L-Rhamnose (Rha) epitope. We synthesized a 20 amino acid glycopeptide TSAPDT(GalNAc)RPAPGSTAPPAHGV from the variable number tandem repeat region of the tumor marker MUC1 containing an N-terminal azido moiety and a tumor-associated α-N-acetyl galactosamine (GalNAc) at the immunogenic DTR motif. The MUC1 antigen was attached to Pam3Cys, a Toll-like receptor-2 ligand via copper (I)-catalyzed azido-alkyne cycloaddtion (CuAAc) chemistry. The Rha-decorated liposomal Pam3Cys-MUC1-Tn 4 vaccine was evaluated in groups of C57BL/6 mice. Some groups were previously immunized to generate anti-Rha antibodies. Anti-Rha antibody expressing mice that received the Rha liposomal vaccine showed higher cellular immunogenicity compared to the control group while maintaining a strong humoral response.

Liposomes used as a vaccine adjuvant-delivery system: From basics to clinical immunization

“…Recently, Karmakar et al made the L-rhamnose (Rha) epitope-anchored liposomes conjugated with the synthetic TLR2a Pam3Cys-linked glycopeptide Ags derived from MUC1, which is a mucin overexpressed on several types of cancers, and had been engineered to contain a GalNAcα1-Ser/Thr segment to have the immunogenic peptide epitopes exposed to immune system (Fig. 8) [142]. In vivo experiments demonstrated that, administered to the Rha-preimmunized C57BL/6 mice, the Rha epitope-and Ag-anchored liposomes remarkably enhanced production of the MUC1-specific CTLs as well as Abs.…”

“…Schematic structure the VADS constructed with the Rha epitope-anchored liposomes loaded with Pam3Cys-linked MUC1 glycopeptide Ags, and the principle underlying the immunostimulatory action of the VADS. Reprinted with permission from Reference[142].…”

Recent Advances in Subunit Vaccine Carriers

“…In recent studies, Karmakar, et al observed improved antigen uptake and cellular response by targeting Fcγ receptors on DCs [ 67 , 68 , 69 ]. The natural abundance of specific natural anti-Rhamnose antibodies in the human population was exploited using L-rhamnose as a targeting ligand [ 70 ].…”

Introductory Chapter: The Modern-Day Drug Discovery

“…With advances in science and technology, the pharmaceutical, health care, and IT industry, accompanied by high-pace shifts in the global economy, bolstered the process of modern-day drug discovery and development to a large significance. Novel interdisciplinary research involving metal and polymer nanoparticles, liposomes, antibodies, and neo-antibiotics in both academia and industries have opened venues for precision diagnosis, targeted drug delivery, and innovative immunotherapy [16][17][18][19][20][21][22][23][24]. Although the classical steps in drug discovery (involving target validation, lead molecule design, chemical synthesis, pre-clinical evaluation, ADME, clinical trials and development for market of the pharmaceutical agents) are followed to date, the distribution of funding at each stage have changed due to the changing global market and healthcare policies [25].…”