Position‐Scanning Peptide Libraries as Particle Immunogens for Improving CD8⁺ T‐Cell Responses

Abstract

Short peptides reflecting major histocompatibility complex (MHC) class I (MHC‐I) epitopes frequently lack sufficient immunogenicity to induce robust antigen (Ag)‐specific CD8+ T cell responses. In the current work, it is demonstrated that position‐scanning peptide libraries themselves can serve as improved immunogens, inducing Ag‐specific CD8+ T cells with greater frequency and function than the wild‐type epitope. The approach involves displaying the entire position‐scanning library onto immunogenic nanoliposomes. Each library contains the MHC‐I epitope with a single randomized position. When a recently identified MHC‐I epitope in the glycoprotein gp70 envelope protein of murine leukemia virus (MuLV) is assessed, only one of the eight positional libraries tested, randomized at amino acid position 5 (Pos5), shows enhanced induction of Ag‐specific CD8+ T cells. A second MHC‐I epitope from gp70 is assessed in the same manner and shows, in contrast, multiple positional libraries (Pos1, Pos3, Pos5, and Pos8) as well as the library mixture give rise to enhanced CD8+ T cell responses. The library mixture Pos1‐3‐5‐8 induces a more diverse epitope‐specific T‐cell repertoire with superior antitumor efficacy compared to an established single mutation mimotope (AH1‐A5). These data show that positional peptide libraries can serve as immunogens for improving CD8+ T‐cell responses against endogenously expressed MHC‐I epitopes.

Low TCR Binding Strength Results in Increased Progenitor-like CD8+ Tumor-Infiltrating Lymphocytes

“…In this dataset, most tumor-reactive cells recognized gp70 423–431 , given the segregation of tetramer-binding clusters (clusters 0, 2, 5, 6, 8, 9, 12) from Tet-negative clusters (clusters 1, 3, 4, 7, 10, 11, 13), and the limited presence of Tet-negative cells within these tetramer-binding clusters. However, a few CD8 + TILs did not recognize the tetramer but were within specific tetramer-positive clusters (clusters 2 and 6), suggesting they may recognize another antigen within the TME ( 44 ). The antigen-specific clusters had a mix of Tet-High and Tet-Low cells, both by cell counts ( Fig.…”

“…TCR engagement is the most significant contributor to the transcriptional profile of TILs as was established by the differences between tetramer-negative and -positive cells, which divided the UMAP space. A sub-dominant TAA from the CT26 tumor, gp70 37–44 , has been identified from the same endogenous retrovirus as gp70 423–431 ( 44 ), and CT26 cells have numerous point mutations in expressed genes ( 46 ). Thus, there is a possibility for T-cell recognition of these peptides, explaining the presence of some tetramer-negative cells within predominantly tetramer-positive clusters.…”

Circularized Nanodiscs for Multivalent Mosaic Display of SARS-CoV-2 Spike Protein Antigens

“…In this study, CoPoP was incorporated into a 25 nm covalently circularized nanodisc to examine whether a mosaic nanodisc decorated with spike proteins from different variants can direct the immune system to produce broadly neutralizing antibodies thanks to dilution of immune dominant, variant specific epitopes with little to no effect on the conserved epitopes and thus favoring immune-recessive conserved epitopes [33]. The plug-and-display approach enabled by CoPoP technology allowed a straightforward production of mosaic nanodisc with different spikes attached randomly [26,34]. We previously reported that 1:4000 cNW50: lipid ratio was used to form a 50 nm nanodisc when 3:2 POPC: POPG lipids were used [31].…”

“…no effect on the conserved epitopes and thus favoring immune-recessive conserved epitopes [33]. The plug-and-display approach enabled by CoPoP technology allowed a straightforward production of mosaic nanodisc with different spikes attached randomly [26,34]. We previously reported that 1:4000 cNW50: lipid ratio was used to form a 50 nm nanodisc when 3:2 POPC: POPG lipids were used [31].…”

The prognostic value of CD39+CD8+ T cells as a potential surrogate marker of tumor-specific T cells in Asian triple-negative breast cancer

“…Consequently, it is di cult to capture tumor-speci c CD8 + T cells using the widely used method of cellular indexing of transcriptomes and epitopes or T cell receptor sequencing 6 . As an alternative, murine tumor models of well-recognized tumor-associated antigens can be used for accurate tumor-speci c CD8 + T cell detection 7,8 . Murine studies and clinical data have indicated that increased frequencies of tumor-localized and peripheral tumor-speci c CD8 + T cells correlate highly with improved TNBC survival 9,10 .…”