Tolerogenic transcriptome landscape in CD8+ T lymphocytes after exposure to erythrocyte-targeted antigens

Abstract

Our group has recently shown induction of antigen-specific T cell tolerance through targeting of the antigen to erythrocytes in situ. The tolerogenic state is characterized by initial proliferation of antigen-specific T cells and subsequent acquisition of signatures associated with both deletional, anergic and regulatory T cell phenotypes. In this study we wished to further understand the molecular mechanisms behind induction of tolerance by erythrocyte-targeted antigens. RNA sequencing was performed to determine how gene expression response is regulated in tolerized ovalbumin-specific CD8+ T cells and which molecular pathways are activated after treatment with this technology. Treatment with erythrocyte-targeted antigens led to the upregulation of genes encoding several TCR co-inhibitory receptors such as CTLA4, PD1, LAG3, TIGIT and CD200R1, and lack of upregulation of cytotoxic and pro-inflammatory signaling molecule genes. Modulation in expression of the master transcription factors Egr2/NFatc1, Nur77 family and E2f1 was also observed, all known to be associated with the natural process of establishment of peripheral tolerance. Expression of these genes differed in response to treatment with soluble ovalbumin or SIINFEKL MHCI peptide, suggesting a specific mechanism of T cell modulation and tolerance induction in response to the erythrocyte-associated forms.