High TCR diversity ensures optimal function andhomeostasis of Foxp3⁺ regulatory Tcells

Abstract

Dominant tolerance to self-antigen requires the presence of sufficient numbers of CD4 1 Foxp31 Treg cells with matching antigen specificity. However, the size and role of TCR repertoire diversity for antigen-specific immuno-regulation through Treg cells is not clear. Here, we developed and applied a novel high-throughput (HT) TCR sequencing approach to analyze the TCR repertoire of Treg cells and revealed the importance of high diversity for Treg-cell homeostasis and function. We found that highly polyclonal Treg cells from WT mice vigorously expanded after adoptive transfer into non-lymphopenic TCR-transgenic recipients with low Treg-cell diversity. In that system, we identified specific Treg-cell TCR preferences in distinct anatomic locations such as the mesenteric LN indicating that Treg cells continuously compete for MHC class-II-presented self-, food-, or flora-antigen. Functionally, we showed that high TCR diversity was required for optimal suppressive function of Treg cells in experimental acute graft versus host disease (GvHD). In conclusion, we suggest that efficient immuno-regulation by Treg cells requires high TCR diversity. Thereby, continuous competition of peripheral Treg cells for limited self-antigen shapes an organ-optimized, yet highly diverse, local TCR repertoire.

Foxp3+ T cells expressing RORγt represent a stable regulatory T-cell effector lineage with enhanced suppressive capacity during intestinal inflammation

“…31 Consistent with the idea that Tregs in the periphery are continuously expanding by encounter of self-antigen, 32 Figure S5). However, we found no qualitative differences in the TCR-a repertoire of these four CD4 þ T-cell subsets, as numbers of shared clonotypes remained similar when comparing distinct subsets (Supplementary Figure S6a).…”

“…Amplicon libraries of rearranged TRAV12 CDR3 regions for the Roche/454 Genome Sequencer FLX þ System were generated as described before. 31 Amplicons were purified by agarose gel electrophoresis and QIAquick Gel Extraction Kit (Qiagen), and quantified by Quant-iT dsDNA HS Assay Kit (Life Technologies/Invitrogen, Darmstadt, Germany). High-throughput sequencing of amplicons was performed on a Genome Sequencer FLX þ system (Roche) according to the manufacturer's recommendations.…”

Differential Postselection Proliferation Dynamics of αβ T Cells, Foxp3+ Regulatory T Cells, and Invariant NKT Cells Monitored by Genetic Pulse Labeling

“…This suggests that, on average, peripheral Tregs in secondary lymphoid organs had proliferated more than CD4 + Foxp3 2 T cells. This matches our previous findings that the peripheral Treg repertoire is very diverse, albeit less diverse than naive ab T cells (25). In contrast, in small intestine and colon, Tregs and CD4 + Foxp3 2 T cells completely lost their H2BeGFP, indicating that they proliferated more than two times after thymic exit (Fig.…”

“…In contrast, CD4 + and CD8 + SP cells still displayed intermediate H2BeGFP levels after thymic maturation and, therefore, had proliferated only to a minor degree. After thymic exit, the sole RTE showing proliferation were CD8 + , which was in line with results from Fink and colleagues (20 (24,25). In summary, we present new data on the different postselection proliferation dynamics of innate ab T cells such as iNKT cells as compared with adaptive ab T cell populations, which include Foxp3 + Tregs.…”

Resident CD4+ T cells accumulate in lymphoid organs after prolonged antigen exposure

“…To investigate these possibilities, we injected FITC into PPs of WT mice and sorted CD62L lo FITC þ and CD62L lo FITC À CD4 þ T cells from individual PP inj together with CD62L lo FITC À CD4 þ T cells from mLN of these mice. Then we sequenced the TCR repertoire of these different populations of CD4 þ T cells focusing on Va8 (TRAV12) family as previously described 19 . To compare the similarity between TCR repertoires, we used the Morisita-Horn index (MHI) as a measure of similarity, which takes into account both the different TCR sequences and their abundances.…”