Postdoctoral Fellow Augusta University Augusta, Georgia, United States
Disclosure(s):
ISHITA TANDON, PhD: No financial relationships to disclose
Introduction/Rationale: Atherosclerosis, contributing to ~one-third of global deaths, is a chronic inflammatory disorder with autoimmune features. Atherosclerosis related antigen - apolipoprotein B (APOB) specific human CD4 T cells have been characterized, and CD8 T cell infiltration and oligoclonal expansion have been observed in human atherosclerotic lesions. Despite studies in mouse atherosclerosis models, APOB-specific CD8 T cells remain unexplored in humans.
Methods: Through in silico analysis, ~0.1% of top-ranked APOB peptides predicted to bind HLA-A02:01 were selected. Using APOB peptide mesopools, PBMCs from HLA-A02:01⁺ donors underwent expansion-based restimulation, followed by flow cytometry. Responses to individual peptides were assessed via IFN ELISpot. Six immunodominant peptides were used to generate tetramers for tracking APOB-specific CD8⁺ T cells in human PBMCs. APOB tetramer-specific CD8 T cells from atherosclerosis patients were analyzed using single-cell RNA and TCR sequencing.
Results: APOB peptide stimulation induced the expression of activation markers (4-1BB, CD69, and CD25), proinflammatory cytokines (IFN and TNF), and cytotoxic molecules (granzyme B and perforin) and enriched for effector memory phenotype in CD8 T cells. APOB epitopes that elicited the strongest IFN ELISpot response were mapped to 2 major antigenic regions in APOB. Tetramers detected APOB-specific circulating CD8 T cells in healthy humans and atherosclerosis patients. APOB-specific CD8 T cells from atherosclerotic humans were activated, as evidenced by high CD45RO and PD-1 expression. APOB-specific CD8 T cells had higher clonal expansion and lower diversity as compared to APOB non-specific CD8 T cells.
Conclusion: Human APOB harbors dominant HLA-I-restricted epitopes that trigger autoreactive CD8 T responses. Future assessment of transcriptomic and TCR data, followed by functional assays, will help characterize the nature and role of APOB-specific CD8 T cells in atherosclerosis.
