Human RORγt ⁺ T _H 17 cells preferentially differentiate from naive FOXP3 ⁺ Treg in the presence of lineage-specific polarizing factors

Abstract

RORγt + T H 17 cells are a proinflammatory CD4 + T-cell population associated with autoimmune tissue injury. In mice, priming of T H 17 requires TGF-β, which alone directs the priming of FOXP3 + regulatory T cells (Treg), in association with inflammatory cytokines. Priming of human T H 17 cells from conventional naive CD4 + T cells under similar conditions, however, has proved difficult to achieve. Here, we report that differentiation of human T H 17 cells preferentially occurs from FOXP3 + naive Treg (NTreg) in the presence of IL-2 and IL-1β and is increased by IL-23 and TGF-β. IL-1β-mediated differentiation correlated with IL-1RI expression in stimulated NTreg and was accompanied by induction of RORγt along with down-regulation of FOXP3. IL-17-secreting cells in NTreg cultures cosecreted TNF-α and IL-2 and contained distinct subpopulations cosecreting or not cosecreting IFN-γ and other T H 17-associated cytokines. Polarized NTreg contained significant subpopulations of CCR6-expressing cells that were highly enriched in IL-17-secreting cells. Finally, analysis of CCR6 expression with respect to that of IL-1RI identified distinct IL-17-secreting subpopulations that had maintained or lost their suppressive functions. Together our results support the concept that priming of human T H 17 from naive CD4 + T cells preferentially takes place from FOXP3 + Treg precursors in the presence of lineage-specific polarizing factors.IL-1 | IL-17 | IL-23 | TGF-β | CD4 T cells

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

“…23,[45][46][47] Although most of these studies indicated that human Foxp3 þ IL-17 þ cells retain regulatory capacity as long as they express Foxp3, it was suggested that they can foster the expression of proinflammatory cytokines and thus behave as ''inflammatory'' Tregs. 23 In addition, in vitro studies showed that human RORgt þ Th17 cells preferentially differentiate from naïve Foxp3 þ T cells that lose their Foxp3 expression 48 that may eventually lead to conversion into pathogenic Th17 cells under inflammatory conditions. 49 Additional studies in mice have shown that Foxp3 þ RORgt þ T cells have a regulatory function during autoimmune diabetes; 50 nevertheless, it was proposed that these cells represent intermediates that can differentiate either toward Foxp3 þ RORgt À Tregs or RORgt þ Foxp3 À Th17 cells.…”

Ex Vivo IL-1 Receptor Type I Expression in Human CD4+ T Cells Identifies an Early Intermediate in the Differentiation of Th17 from FOXP3+ Naive Regulatory T Cells

“…We have recently shown that, after stimulation in the presence of Th17-polarizing cytokines, human Th17 preferentially differentiate from NnTreg rather than from conventional naive CD4 + T cells (12 Fig. 6, induction of IL-1RI expression was an early event of Th17 cell differentiation from NnTreg, as it was detected in a significant fraction of the cells early after stimulation, before cell division.…”

“…In addition, MTreg contain a hybrid subpopulation of cells coexpressing FOXP3 and RORgt that exert suppressive functions but concomitantly secrete IL-17 ex vivo (9,10). Finally, in the presence of IL-1, IL-2, TGF-b, and IL-23, human Th17 cells preferentially differentiate from natural naive regulatory T cells (NnTreg), a population of thymically derived human regulatory T cell (Treg) precursors (11), rather than from conventional CD4 + CD25 2 naive T cells (12). Together, these data suggest that the differentiation pathway of Treg and Th17 cells is partially common.…”

“…For control of input RNA, we used TaqMan probe (FAM-59-AAGGTGAAGGTCGGAGTCAACGGAT-TTG-39-TAMRA) and primers (59-CCACATCGCTCAGACACCAT-39 and 59-CCAGGCGCCCAATACG-3) for GAPDH. / well in 96-well U-bottom plates) were stimulated with anti-CD2/CD3/ CD28-coated microbeads according to the manufacturer's instructions (Miltenyi Biotec) in the absence or presence of IL-1b (10 ng/ml; R&D Systems), IL-23 (100 ng/ml; R&D Systems), and TGF-b (10 ng/ml; PeproTech), as previously described (12). Ex vivo-sorted IL-1RI + and IL-1RI…”

Helios+ and Helios− Cells Coexist within the Natural FOXP3+ T Regulatory Cell Subset in Humans

“…Numerous studies have shown that FOXP3-expressing Tregs can be divided into two distinct subsets: naturally occurring Tregs (nTregs), and peripherally induced Tregs (iTregs), which differentiate under tolerogenic conditions in peripheral lymphoid tissues (4,5). FOXP3-expressing nTregs develop in the thymus via central tolerance mechanisms and, upon egress, they express the naive T cell marker CD45RA until they encounter their cognate Ag and become activated in the periphery (6,7). Their TCR repertoire is diverse but thought to be largely restricted to self-Ags (8).…”