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Modification of Regulatory T Cell Epitopes Promotes Effector T Cell Responses to Aspartyl/Asparaginyl β-Hydroxylase
Sebastian Wirsching1, Michael Fichter2,3, Maximiliano L Cacicedo1
1Children's Hospital, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany.
Abstract:
Cancer is a leading cause of death worldwide. The search for innovative therapeutic approaches is a principal focus of medical research. Vaccine strategies targeting a number of tumor-associated antigens are currently being evaluated. To date, none have garnered significant success. Purportedly, an immunosuppressive tumor microenvironment and the accumulation of regulatory T cells contribute to a lack of tumor vaccine efficacy. Aspartyl/asparaginyl β-hydroxylase (ASPH), a promising therapeutic target, is overexpressed in a variety of malignant tumors but is expressed negligibly in normal tissues. Computer analysis predicted that ASPH expresses four peptide sequences (epitopes) capable of stimulating regulatory T cell activity. The abolition of these putative regulatory T cell epitopes increased the CD4+ and CD8+ effector T cell responses to monocyte-derived dendritic cells pulsed with a modified, epitope-depleted version of ASPH in an ex vivo human lymphoid tissue-equivalent coculture system while simultaneously decreasing the overall number of FoxP3+ regulatory T cells. These findings suggest that the efficacy of all new vaccine candidates would profit from screening and eliminating potential tolerogenic regulatory T cell epitopes.
Insights
Removing regulatory T cell epitopes from cancer vaccines, like ASPH (Aspartyl/asparaginyl β-hydroxylase), can enhance anti-tumor immune responses. This strategy boosts effector T cells while reducing immunosuppressive cells, improving vaccine efficacy.
Area of Science:
- Oncology
- Immunology
- Vaccine Development
Background:
- Cancer remains a leading global cause of mortality, driving research into novel therapeutic strategies.
- Current tumor vaccine approaches show limited success, potentially due to an immunosuppressive tumor microenvironment and regulatory T cells.
- Aspartyl/asparaginyl β-hydroxylase (ASPH) is a promising cancer target overexpressed in tumors but minimally in normal tissues.
Purpose of the Study:
- To investigate the impact of removing regulatory T cell epitopes from the ASPH target on anti-tumor immune responses.
- To assess the potential of modifying vaccine candidates to improve efficacy by targeting T cell regulation.
Main Methods:
- Computational analysis identified four potential regulatory T cell epitopes within ASPH.
- An ex vivo human lymphoid tissue-equivalent coculture system was used.
- Monocyte-derived dendritic cells were pulsed with an epitope-depleted ASPH variant.
Main Results:
- Eliminating ASPH's regulatory T cell epitopes enhanced CD4+ and CD8+ effector T cell responses.
- A decrease in the number of FoxP3+ regulatory T cells was observed.
- The modified ASPH vaccine candidate demonstrated improved T cell activation in vitro.
Conclusions:
- Screening and removing tolerogenic regulatory T cell epitopes from vaccine candidates is crucial.
- This strategy holds promise for improving the efficacy of cancer vaccines.
- Targeting T cell regulation offers a new avenue for enhancing anti-tumor immunity.
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