Extended Data Fig. 10: Identification of TPRL as an antigen from Bacteroides species.
From: Mapping the T cell repertoire to a complex gut bacterial community
a, To search for the antigenic epitope in TPRL from Bacteroides eggerthii, a library of truncated peptides was synthesized. 4 Bacteroides-reactive TCR hybridomas were mixed and co-cultured with truncated peptides and dendritic cells. The degree of TCR stimulation was estimated by assaying the concentration of IL-2 in the culture supernatant by ELISA. TPRL29-53 (Peptide 3, SDYFTVTPQVLEAVGGKVPATINGK) stimulated the mixed TCR hybridomas. b, We found that TCR H2-11, H2-30, and H1-14 are reactive to Peptide 3 from TPRL by coculturing each Bacteroides-reactive TCR hybridoma with Peptides 2 and 3. c, Results of a BLAST search using the antigenic epitope TPRL29-53 as a query; the results shown are from strains in hCom1d and hCom2d. d, Predicted crystal structure of the TPRL from AlphaFold2. The TPRL29-53 epitope, shown in red, lies within a beta-sheet in the N-terminal domain. e, Induction of TPRL-specific T cells in vivo. Germ-free C57BL/6 mice were colonized with hCom2d. After two weeks, intestinal T cells were isolated and cocultured with TPRL29-53 and dendritic cells. Nur77 expression in T cell subsets was analyzed by FACS to monitor TCR stimulation (see Extended Data Fig. 1a, c for the gating strategy). In hCom1d and hCom2d-colonized mice, Th17 and pTreg cells showed an antigen-specific response to SBP. p-values were calculated using a two-sided t-test by comparison to PBS treatment as a negative control. *p < 0.05. Data shown are mean ± standard deviations. n = 5, 8 mice per group from one experiment.
