The Toll-Like Receptor 2 Pathway Establishes Colonization by a Commensal of the Human Microbiota
June L. Round1,*,
S. Melanie Lee1,
Talal A. Chatila3, and
Sarkis K. Mazmanian1,*
1 Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
2 Department of Pathology, Department of Pediatrics, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
3 Division of Immunology, Allergy and Rheumatology, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Fig. 2. PSA signals through TLR2 on CD4+ T cells to suppress TH17 cell responses. (A) Bone marrow–derived dendritic cells from wild-type (WT) or Tlr2–/– mice were incubated with splenic CD4+ T cells. Amounts of secreted IL-10 were determined by enzyme-linked immunosorbent assay (ELISA). Error bars represent SDs from two independent assays performed in quadruplicate. ***P < 0.001; NS, not significant. (B) CD4+ T cells were isolated from WT mice, and the indicated knockout mice and cells were stimulated as in (A). MyD is Myd88–/–. IL-10 was assayed by ELISA. **P < 0.01. Error bars represent SDs for quadruplicate samples and are representative of two independent trials. (C) CD4+Foxp3+ Tregs were purified from Foxp3EGFP mice (26) and Tlr2–/– X Foxp3EGFP mice and stimulated with plate-bound antibodies against CD3 and recombinant TGF-β, with PSA or with the indicated TLR ligands. Equal numbers of live cultured Tregs were then incubated with CFSE (carboxyfluorescein diacetate succinimidyl ester)–pulsed responder cells (CD4+Foxp3–). Percent suppression is determined by the ratio of proliferating responder cells in each condition relative to proliferation in the absence of added Tregs. Error bars are SDs from a single experiment performed in duplicate and are representative of two independent trials. (D and E) Germ-free Rag1–/– animals were reconstituted with CD4+ T cells from WT or Tlr2–/– mice and then mono-associated with either WT B. fragilis or B. fragilisPSA. Colonic LPLs were isolated and analyzed for TH17 cell proportions by flow cytometry. Plots are gated on CD4+ cells. (D) Each symbol represents an individual animal (n = 3 to 4 mice per group), and data are representative of two independent trials. **P < 0.01; ***P < 0.001.|