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Transloading of tumor antigen-derived peptides into antigen-presenting cells
Abstract:
The discovery of a steadily growing number of tumor antigens (TAs) has made generic, cell-free, peptide-based cancer vaccines a possible alternative to cytokine-transfected autologous cellular cancer vaccines. The major drawback of peptide vaccines, however, is the poor immunogenicity of peptides. It is commonly thought that for the induction of an effective anticancer immune response, antigen-presenting cells (APCs) have to display TA-derived peptides to T lymphocytes. Polycationic amino acids have been employed in the past to enhance transport of proteins into cells. In a systematic study, the ability of different cationic polymers to transfer fluorescence-tagged peptides to APCs was investigated. We were able to show that several compounds enhance uptake of fluorescence-labeled peptides by APCs to different degrees. The most efficient compound identified, polyarginine (pArg), enhanced peptide delivery by more than 2 logs as compared with cells treated with peptide alone, whereas polylysine (pLys) treatment resulted in approximately 10-fold increased levels of fluorescence. Augmentation of peptide uptake was concentration-dependent, and the molecular weight of pArg or pLys also influenced peptide delivery. Furthermore, highly negatively charged peptides appear to be delivered with higher efficiency, although neutral peptides were also taken up at enhanced rates. Whereas peptide uptake mediated by pLys appears to be due to an at least transient permeabilization of cell membranes, peptide delivery in the presence of pArg may rely on endocytic processes. TA-derived peptides applied as cancer vaccines in conjunction with polycations afforded antitumor protection in animal models.
Insights
Cationic polymers like polyarginine enhance the delivery of tumor antigen peptides to antigen-presenting cells (APCs), improving cancer vaccine potential. This research offers a promising strategy for more effective cancer immunotherapies.
Area of Science:
- Immunology
- Biotechnology
- Cancer Research
Background:
- Tumor antigens (TAs) enable peptide-based cancer vaccines as an alternative to cellular vaccines.
- Peptide vaccines suffer from poor immunogenicity, hindering effective anticancer immune responses.
- Antigen-presenting cells (APCs) must present TA-derived peptides to T lymphocytes for immune activation.
Purpose of the Study:
- To investigate the efficacy of cationic polymers in enhancing the delivery of peptides to APCs.
- To identify specific cationic polymers that can improve peptide uptake by APCs for cancer vaccine development.
- To understand the mechanisms by which cationic polymers facilitate peptide delivery.
Main Methods:
- Systematic investigation of various cationic polymers for their ability to transfer fluorescence-tagged peptides to APCs.
- Comparative analysis of peptide delivery enhancement by different polymers, including polyarginine (pArg) and polylysine (pLys).
- Evaluation of factors influencing peptide delivery, such as polymer concentration, molecular weight, and peptide charge.
Main Results:
- Several cationic compounds significantly enhanced fluorescence-labeled peptide uptake by APCs.
- Polyarginine (pArg) demonstrated superior peptide delivery enhancement (>2 logs) compared to peptide alone.
- Polylysine (pLys) increased peptide uptake approximately 10-fold; uptake efficiency correlated with peptide charge and was concentration-dependent.
- pLys-mediated uptake involved membrane permeabilization, while pArg-mediated uptake appeared to involve endocytosis.
Conclusions:
- Cationic polymers, particularly pArg, can substantially enhance peptide delivery to APCs, overcoming a key limitation of peptide vaccines.
- TA-derived peptides combined with polycations show promise for inducing antitumor protection in preclinical models.
- This strategy offers a potential pathway to develop more immunogenic and effective peptide-based cancer vaccines.