FOXP3+ regulatory T cell prevent inflammation but are paradoxically increased in ulcerative colitis (UC). Local T-cell activation has been hypothesized to account for increased FOXP3 expression in colon lamina propria (LP) T cells.Methods:
To see if human FOXP3+ LP T cells are an activated fraction of otherwise FOXP3− effector T cells and explore their clonal diversity in health and disease, we deep sequenced clonally unique T-cell receptor hypervariable regions of FOXP3+ and FOXP3−CD4+ T-cell subpopulations from inflamed versus noninflamed colon LP or mesenteric lymph nodes of patients with or without UC.Results:
The clonal diversity of each LP T-cell population was not different between patients with versus without UC. Repertoire overlap was only seen between a minority of FOXP3+ and FOXP3− cells, including recently activated CD38+ cells and Th17-like CD161+ effector T cells, but this repertoire overlap was not different between patients with versus without UC and was no larger than the overlap between Helios− and Helios+ FOXP3+ cells.Conclusions:
Thus, at steady state, only a minority of FOXP3+, and particularly Helios+, T cells share a T-cell receptor sequence with FOXP3− effector populations in the colon LP, even in UC, revealing distinct clonal origins for LP regulatory T cell and effector T cells in humans.