Increased plasticity of non-classic Th1 cells toward the Th17 phenotype

Abstract

Objectives: To analyze occurrence and plasticity of two recently described distinct subtypes of Th1 cells named classic (CD161−/CCR6−) and non-classic (CD161+/CCR6+) Th1 cells in early rheumatoid arthritis (RA) patients and healthy controls (HCs).

Methods: Frequencies of in vivo-generated Th1 cell populations were assessed after cytokine secretion assay for IFNγ/IL-17 and surface staining for CD161/CCR6. Viable Th1 cells (IFNγ+IL-17−) were sorted into classic Th1 (CD161-CCR6−) and non-classic Th1 (CD161+CCR6+) cells, trans-differentiated under different Th cell-inducing conditions, and assessed for plastic changes by analyzing the Th cell-associated cytokine and transcription factor profiles.

Results: Ex vivo frequencies of classic (CD161−CCR6−) and non-classic (CD161+CCR6+) Th1 cells as well as related Th1 cell subpopulations CD161+CCR6− and CD161−/CCR6+ did not differ significantly between RA and HCs. However, trans-differentiation of ex vivo non-classic (CD161+CCR6+) and CD161−/CCR6+ Th1 cells resulted in a substantial shift toward Th17 and Th1/Th17 phenotypes, particularly under Th17-inducing conditions. In contrast, classic (CD161−/CCR6−) and CD161+CCR6− Th1 cells showed higher plasticity towards IL-4-producing cells, most of them shifting to a Th1/Th2 phenotype.

Conclusion: Whereas non-classic (CD161+/CCR6+) and CD161-CCR6+ Th1 cells demonstrated an increased plasticity towards IL-17- phenotypes, classic Th1 and CD161+CCR6− Th1 cells showed more plasticity towards IL-4-producing phenotypes.

Keywords:

• Plasticity
• non-classic Th1
• classic Th1
• Th17 cells
• rheumatoid arthritis

Acknowledgements

The authors are indebted to all patients and healthy individuals for their invaluable willingness to donate blood.

Conflict of interest

None.

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinschaft [grant project LE 2784/1-1, number 192568016] and by the FöFoLe Programme of the Medical Faculty of LMU Munich.