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Focused specificity of intestinal TH17 cells towards commensal bacterial antigens.

Yang Y, Torchinsky MB, Gobert M, Xiong H, Xu M, Linehan JL, Alonzo F, Ng C, Chen A, Lin X, Sczesnak A, Liao JJ, Torres VJ, Jenkins MK, Lafaille JJ, Littman DR - Nature (2014)

Bottom Line: However, the specificity of TH17 cells, the mechanism of their induction by distinct bacteria, and the means by which they foster tissue-specific inflammation remain unknown.The match of T-cell effector function with antigen specificity is thus determined by the type of bacteria that produce the antigen.These findings have significant implications for understanding how commensal microbiota contribute to organ-specific autoimmunity and for developing novel mucosal vaccines.

View Article: PubMed Central - PubMed

Affiliation: The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016, USA.

ABSTRACT
T-helper-17 (TH17) cells have critical roles in mucosal defence and in autoimmune disease pathogenesis. They are most abundant in the small intestine lamina propria, where their presence requires colonization of mice with microbiota. Segmented filamentous bacteria (SFB) are sufficient to induce TH17 cells and to promote TH17-dependent autoimmune disease in animal models. However, the specificity of TH17 cells, the mechanism of their induction by distinct bacteria, and the means by which they foster tissue-specific inflammation remain unknown. Here we show that the T-cell antigen receptor (TCR) repertoire of intestinal TH17 cells in SFB-colonized mice has minimal overlap with that of other intestinal CD4(+) T cells and that most TH17 cells, but not other T cells, recognize antigens encoded by SFB. T cells with antigen receptors specific for SFB-encoded peptides differentiated into RORγt-expressing TH17 cells, even if SFB-colonized mice also harboured a strong TH1 cell inducer, Listeria monocytogenes, in their intestine. The match of T-cell effector function with antigen specificity is thus determined by the type of bacteria that produce the antigen. These findings have significant implications for understanding how commensal microbiota contribute to organ-specific autoimmunity and for developing novel mucosal vaccines.

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Intestinal Th17 cells are specific for SFB- and other microbiota-derived antigens(a) Selective activation of intestinal GFP+ CD4+ T cells from Il-23rGFP/+ mice by fecal extract from SFB-monoassociated mice. Forward scatter (FSC) was evaluated after 2 days. (b) Activation of SILP CD4+ T cells from B6 Tac mice and B6 Jax mice with fecal extract from SFB-monoassociated mice. (c) IL17A ELISPOT assay of intestinal GFP+ CD4+ T cells from SFB-colonized Il-23rGFP/+ mice treated with indicated stimuli. Left: Representative ELISPOT images. Right: Compilation of results from multiple animals. Each symbol represents cells from a separate animal.
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Figure 11: Intestinal Th17 cells are specific for SFB- and other microbiota-derived antigens(a) Selective activation of intestinal GFP+ CD4+ T cells from Il-23rGFP/+ mice by fecal extract from SFB-monoassociated mice. Forward scatter (FSC) was evaluated after 2 days. (b) Activation of SILP CD4+ T cells from B6 Tac mice and B6 Jax mice with fecal extract from SFB-monoassociated mice. (c) IL17A ELISPOT assay of intestinal GFP+ CD4+ T cells from SFB-colonized Il-23rGFP/+ mice treated with indicated stimuli. Left: Representative ELISPOT images. Right: Compilation of results from multiple animals. Each symbol represents cells from a separate animal.

Mentions: How SFB induces Th17 cells and how these cells contribute to self-reactive pathological responses remain key unanswered questions. A recent study, using mice with monoclonal TCRs, suggested that induction of Th17 cells by SFB or other microbiota is independent of cognate antigen recognition 15. To further evaluate mucosal effector T cell induction in a physiological setting, we undertook an examination of the repertoire and specificity of naturally-arising Th17 cells. To facilitate analyzing live Th17 cells, we used Il-23rGFP reporter mice 16, as among CD4+ T cells, only this subset expresses IL-23R. We first asked if SILP Th17 cells are in general responsive to gut luminal commensal antigens. GFP+ (Th17) and GFP- (non-Th17) CD4+ T cells, purified from Il-23rGFP/+ C57BL/6 (B6) mice that had been colonized with SFB, were incubated with splenic antigen-presenting cells (APCs) and autoclaved small intestinal luminal content of mice from the Jackson laboratory (Jax) and Taconic Farms (Tac). We used the measure of forward scatter (FSC) as a surrogate readout for T cell activation. Intriguingly, only Th17 cells mounted a detectable response to Tac antigens (Extended Data Fig. 1a). SFB is one of the bacteria unique to Taconic flora 8. Thus we repeated the assay with fecal material from SFB-monoassociated mice (SFB-mono antigens) and detected a robust response only among GFP+ cells (Fig. 1a). These cells did not respond to MHCII-deficient APCs loaded with SFB-mono antigens, indicating that the activation was dependent on antigen presentation (Extended Data Fig. 1b). SFB-mono antigens selectively stimulated total CD4+ T cells from B6 Tac mice, but not those from B6 Jax mice, consistent with in vivo priming of SFB-specific Th17 cells (Fig. 1b), and any bystander effect in this assay was negligible (Extended Data Fig. 1c). Next, we used an IL-17A ELISPOT assay to quantify the percentage of Th17 cells from SFB-colonized mice responding to commensal antigens. GFP+ cells had a relatively weak response towards Jax antigens, but had a robust response towards Tac antigens. Significantly, SFB mono-associated mouse fecal antigens stimulated over 60% of the Th17 cells (Fig. 1c). In contrast, there was no response of Th17 cells to fecal material from germ-free mice (data not shown). Thus, the majority of Th17 cells in the SILP of SFB-colonized mice react with SFB-derived antigens, while a small proportion respond to non-SFB antigen, indicating that most Th17 cells are specific for bacteria in the intestinal lumen.


Focused specificity of intestinal TH17 cells towards commensal bacterial antigens.

Yang Y, Torchinsky MB, Gobert M, Xiong H, Xu M, Linehan JL, Alonzo F, Ng C, Chen A, Lin X, Sczesnak A, Liao JJ, Torres VJ, Jenkins MK, Lafaille JJ, Littman DR - Nature (2014)

Intestinal Th17 cells are specific for SFB- and other microbiota-derived antigens(a) Selective activation of intestinal GFP+ CD4+ T cells from Il-23rGFP/+ mice by fecal extract from SFB-monoassociated mice. Forward scatter (FSC) was evaluated after 2 days. (b) Activation of SILP CD4+ T cells from B6 Tac mice and B6 Jax mice with fecal extract from SFB-monoassociated mice. (c) IL17A ELISPOT assay of intestinal GFP+ CD4+ T cells from SFB-colonized Il-23rGFP/+ mice treated with indicated stimuli. Left: Representative ELISPOT images. Right: Compilation of results from multiple animals. Each symbol represents cells from a separate animal.
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Figure 11: Intestinal Th17 cells are specific for SFB- and other microbiota-derived antigens(a) Selective activation of intestinal GFP+ CD4+ T cells from Il-23rGFP/+ mice by fecal extract from SFB-monoassociated mice. Forward scatter (FSC) was evaluated after 2 days. (b) Activation of SILP CD4+ T cells from B6 Tac mice and B6 Jax mice with fecal extract from SFB-monoassociated mice. (c) IL17A ELISPOT assay of intestinal GFP+ CD4+ T cells from SFB-colonized Il-23rGFP/+ mice treated with indicated stimuli. Left: Representative ELISPOT images. Right: Compilation of results from multiple animals. Each symbol represents cells from a separate animal.
Mentions: How SFB induces Th17 cells and how these cells contribute to self-reactive pathological responses remain key unanswered questions. A recent study, using mice with monoclonal TCRs, suggested that induction of Th17 cells by SFB or other microbiota is independent of cognate antigen recognition 15. To further evaluate mucosal effector T cell induction in a physiological setting, we undertook an examination of the repertoire and specificity of naturally-arising Th17 cells. To facilitate analyzing live Th17 cells, we used Il-23rGFP reporter mice 16, as among CD4+ T cells, only this subset expresses IL-23R. We first asked if SILP Th17 cells are in general responsive to gut luminal commensal antigens. GFP+ (Th17) and GFP- (non-Th17) CD4+ T cells, purified from Il-23rGFP/+ C57BL/6 (B6) mice that had been colonized with SFB, were incubated with splenic antigen-presenting cells (APCs) and autoclaved small intestinal luminal content of mice from the Jackson laboratory (Jax) and Taconic Farms (Tac). We used the measure of forward scatter (FSC) as a surrogate readout for T cell activation. Intriguingly, only Th17 cells mounted a detectable response to Tac antigens (Extended Data Fig. 1a). SFB is one of the bacteria unique to Taconic flora 8. Thus we repeated the assay with fecal material from SFB-monoassociated mice (SFB-mono antigens) and detected a robust response only among GFP+ cells (Fig. 1a). These cells did not respond to MHCII-deficient APCs loaded with SFB-mono antigens, indicating that the activation was dependent on antigen presentation (Extended Data Fig. 1b). SFB-mono antigens selectively stimulated total CD4+ T cells from B6 Tac mice, but not those from B6 Jax mice, consistent with in vivo priming of SFB-specific Th17 cells (Fig. 1b), and any bystander effect in this assay was negligible (Extended Data Fig. 1c). Next, we used an IL-17A ELISPOT assay to quantify the percentage of Th17 cells from SFB-colonized mice responding to commensal antigens. GFP+ cells had a relatively weak response towards Jax antigens, but had a robust response towards Tac antigens. Significantly, SFB mono-associated mouse fecal antigens stimulated over 60% of the Th17 cells (Fig. 1c). In contrast, there was no response of Th17 cells to fecal material from germ-free mice (data not shown). Thus, the majority of Th17 cells in the SILP of SFB-colonized mice react with SFB-derived antigens, while a small proportion respond to non-SFB antigen, indicating that most Th17 cells are specific for bacteria in the intestinal lumen.

Bottom Line: However, the specificity of TH17 cells, the mechanism of their induction by distinct bacteria, and the means by which they foster tissue-specific inflammation remain unknown.The match of T-cell effector function with antigen specificity is thus determined by the type of bacteria that produce the antigen.These findings have significant implications for understanding how commensal microbiota contribute to organ-specific autoimmunity and for developing novel mucosal vaccines.

View Article: PubMed Central - PubMed

Affiliation: The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016, USA.

ABSTRACT
T-helper-17 (TH17) cells have critical roles in mucosal defence and in autoimmune disease pathogenesis. They are most abundant in the small intestine lamina propria, where their presence requires colonization of mice with microbiota. Segmented filamentous bacteria (SFB) are sufficient to induce TH17 cells and to promote TH17-dependent autoimmune disease in animal models. However, the specificity of TH17 cells, the mechanism of their induction by distinct bacteria, and the means by which they foster tissue-specific inflammation remain unknown. Here we show that the T-cell antigen receptor (TCR) repertoire of intestinal TH17 cells in SFB-colonized mice has minimal overlap with that of other intestinal CD4(+) T cells and that most TH17 cells, but not other T cells, recognize antigens encoded by SFB. T cells with antigen receptors specific for SFB-encoded peptides differentiated into RORγt-expressing TH17 cells, even if SFB-colonized mice also harboured a strong TH1 cell inducer, Listeria monocytogenes, in their intestine. The match of T-cell effector function with antigen specificity is thus determined by the type of bacteria that produce the antigen. These findings have significant implications for understanding how commensal microbiota contribute to organ-specific autoimmunity and for developing novel mucosal vaccines.

Show MeSH
Related in: MedlinePlus