Antigenic Challenge Influences Epigenetic Changes in Antigen-Specific T Regulatory Cells

Area of Science:

• Immunology
• Epigenetics
• Cellular Biology

Background:

• Human regulatory T cells (Tregs) are crucial for immune tolerance by controlling effector T cells (Teffs).
• Antigen-specific Tregs can be generated using monocytes loaded with type 1 diabetes-associated antigens.
• Insulin β chain peptide 9-23 demonstrated superior efficiency in Treg suppression compared to whole insulin.

Purpose of the Study:

• To investigate the epigenetic modifications influencing functional differences in antigen-specific Tregs.
• To compare the effects of whole insulin versus insulin β chain peptide 9-23 on Treg and Teff epigenetic profiles.

Main Methods:

• Analysis of specific (proliferating) and unspecific (non-proliferating) Treg and Teff subsets.
• Quantification of gene expression (qRT-PCR), DNA methylation (qMSP, ELISA), and histone modifications (ELISA).
• Stimulation using monocytes loaded with whole insulin (INS), insulin β chain peptide 9-23 (B:9-23), or anti-CD3/anti-CD28 beads (POLY).

Main Results:

• Tregs stimulated with insulin β chain peptide 9-23 (Tregs SPEC_B:9-23) exhibited the highest expression of regulatory genes.
• Tregs SPEC_B:9-23 showed significantly lower global DNA and TSDR methylation compared to Tregs SPEC_INS.
• Epigenetic modifications, including post-translational modifications (PTMs), differed between Tregs and Teffs, with distinct patterns observed for INS and B:9-23 stimulation.

Conclusions:

• Whole insulin and insulin β chain peptide 9-23 induce differential epigenetic changes in CD4+ T cells.
• Insulin β chain peptide 9-23 preferentially promotes specific Tregs, enhancing their function.
• Whole insulin activates both Tregs and Teffs, suggesting a broader immune response compared to the peptide.