Increased antigen presentation efficiency by coupling antigens to MHC class I trafficking signals

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• Conventional vaccine strategies aim to enhance T cell responses by targeting antigens to specific cellular compartments.
• Previous methods involved linking antigens to lysosomal or endosomal signals to improve CD4+ T cell responses via MHC class II presentation.

Purpose of the Study:

• To investigate the efficacy of a novel chimeric fusion protein strategy using an N-terminal leader peptide and an MHC class I trafficking signal (MITD) for antigen presentation.
• To evaluate the impact of MITD on both MHC class I and class II epitope presentation in dendritic cells (DCs).

Main Methods:

• Constructing chimeric fusion proteins with an N-terminal leader peptide and MITD attached to the C terminus of antigens.
• Analyzing the subcellular distribution of these fusion proteins in immature and mature human and murine dendritic cells.
• Assessing T cell responses in vitro and in vivo using DCs transfected with antigen-encoding RNA and immunizing mice.

Main Results:

• MITD fusion proteins significantly enhanced the presentation of both MHC class I and class II epitopes in dendritic cells.
• These fusion proteins exhibited maturation state-dependent subcellular localization in DCs, mimicking MHC molecule dynamics.
• In vitro and in vivo analyses revealed a profoundly higher stimulatory capacity of MITD fusion proteins compared to wild-type controls.
• Efficient expansion of antigen-specific CD8+ and CD4+ T cells with improved effector functions was observed.
• Application to CMVpp65 and NY-ESO-1 antigens in relevant patient populations demonstrated simultaneous, polyepitopic expansion of both CD8+ and CD4+ T cells.

Conclusions:

• The MITD trafficking signal is a potent tool for enhancing antigen presentation and T cell immunity.
• This strategy enables the simultaneous expansion of both CD8+ and CD4+ T cells, offering a promising approach for vaccine development.
• The observed distinct CD8+ T cell specificities and broad CD4+ T cell repertoire highlight the versatility of this method for diverse immune responses.