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ICOS and Bcl6-dependent pathways maintain a CD4 T cell population with memory-like properties during tuberculosis.

Moguche AO, Shafiani S, Clemons C, Larson RP, Dinh C, Higdon LE, Cambier CJ, Sissons JR, Gallegos AM, Fink PJ, Urdahl KB - J. Exp. Med. (2015)

Bottom Line: When transferred into uninfected animals, these cells persist, mount a robust recall response, and provide superior protection to Mtb rechallenge when compared to terminally differentiated Th1 cells that reside preferentially in the lung-associated vasculature.Thus, the molecular pathways required to maintain Mtb-specific CD4 T cells during ongoing infection are similar to those that maintain memory CD4 T cells in scenarios of antigen deprivation.These results suggest that vaccination strategies targeting the ICOS and Bcl6 pathways in CD4 T cells may provide new avenues to prevent TB.

View Article: PubMed Central - HTML - PubMed

Affiliation: Seattle Biomedical Research Institute (renamed Center for Infectious Disease Research), Seattle, WA 98109 Department of Immunology, University of Washington School of Medicine, Seattle, WA 98104.

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ESAT-6–specific CD4 T cells produce IFN-γ in a TCR signaling–dependent manner. Mice were infected as described in Fig. 1. (A) Intracellular IFN-γ was assessed by flow cytometry directly ex vivo using lung cells (150 d after infection) processed in the presence of Brefeldin A. Gating strategy and representative flow cytometry plots for naive CD44low (gray), nontetramer-binding CD44hi (blue), and ESAT-6 tetramer-binding CD44hi (red) CD4 T cells are shown. (B) Flow cytometry plots show intracellular IFN-γ, or staining with isotype matched control, in ESAT-6–specific CD4 T cells (70 d after infection). Graph shows the percentage of ESAT-6 tetramer-binding or naive CD44low T cells producing IFN-γ at the indicated time points. (C) Mice infected with Mtb 35 d prior were treated intraperitoneally with either cyclosporine-A (CsA) or vehicle, and ESAT-6–specific cells in the lung were assessed for intracellular IFN-γ as in A and B. Numbers in parentheses represent the percentage of ESAT-6 tetramer-binding CD4 T cells producing IFN-γ and the graph shows this value for each mouse and the mean ± SEM for each group. Significance was determined by two-tailed Student’s t test (**, P < 0.01). Data are representative of two independent experiments with four to five mice per group.
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fig2: ESAT-6–specific CD4 T cells produce IFN-γ in a TCR signaling–dependent manner. Mice were infected as described in Fig. 1. (A) Intracellular IFN-γ was assessed by flow cytometry directly ex vivo using lung cells (150 d after infection) processed in the presence of Brefeldin A. Gating strategy and representative flow cytometry plots for naive CD44low (gray), nontetramer-binding CD44hi (blue), and ESAT-6 tetramer-binding CD44hi (red) CD4 T cells are shown. (B) Flow cytometry plots show intracellular IFN-γ, or staining with isotype matched control, in ESAT-6–specific CD4 T cells (70 d after infection). Graph shows the percentage of ESAT-6 tetramer-binding or naive CD44low T cells producing IFN-γ at the indicated time points. (C) Mice infected with Mtb 35 d prior were treated intraperitoneally with either cyclosporine-A (CsA) or vehicle, and ESAT-6–specific cells in the lung were assessed for intracellular IFN-γ as in A and B. Numbers in parentheses represent the percentage of ESAT-6 tetramer-binding CD4 T cells producing IFN-γ and the graph shows this value for each mouse and the mean ± SEM for each group. Significance was determined by two-tailed Student’s t test (**, P < 0.01). Data are representative of two independent experiments with four to five mice per group.

Mentions: We detected IFN-γ in ESAT-6 tetramer-binding and CD44hi (but not CD44low) CD4 T cells (Fig. 2 A) using intracellular cytokine staining of T cells directly ex vivo without in vitro restimulation (Shafiani et al., 2013). At 16 d after infection, ~20% of ESAT-6–specific T cells recovered from the lungs produced IFN-γ, and this percentage gradually increased to ~40% on day 300 (Fig. 2 B). IFN-γ production was dependent on TCR signaling in at least half of these cells because administration of cyclosporine A (CsA; an inhibitor of proximal TCR-mediated signaling; Schreiber and Crabtree, 1992), 4 h before euthanasia blocked IFN-γ production in ~50% of the cells (Fig. 2 C). Collectively, our results indicate that ESAT-6 antigen is readily available for T cell recognition throughout infection and high numbers of ESAT-6–specific T cells are maintained in the lung in the presence of chronic antigenic stimulation.


ICOS and Bcl6-dependent pathways maintain a CD4 T cell population with memory-like properties during tuberculosis.

Moguche AO, Shafiani S, Clemons C, Larson RP, Dinh C, Higdon LE, Cambier CJ, Sissons JR, Gallegos AM, Fink PJ, Urdahl KB - J. Exp. Med. (2015)

ESAT-6–specific CD4 T cells produce IFN-γ in a TCR signaling–dependent manner. Mice were infected as described in Fig. 1. (A) Intracellular IFN-γ was assessed by flow cytometry directly ex vivo using lung cells (150 d after infection) processed in the presence of Brefeldin A. Gating strategy and representative flow cytometry plots for naive CD44low (gray), nontetramer-binding CD44hi (blue), and ESAT-6 tetramer-binding CD44hi (red) CD4 T cells are shown. (B) Flow cytometry plots show intracellular IFN-γ, or staining with isotype matched control, in ESAT-6–specific CD4 T cells (70 d after infection). Graph shows the percentage of ESAT-6 tetramer-binding or naive CD44low T cells producing IFN-γ at the indicated time points. (C) Mice infected with Mtb 35 d prior were treated intraperitoneally with either cyclosporine-A (CsA) or vehicle, and ESAT-6–specific cells in the lung were assessed for intracellular IFN-γ as in A and B. Numbers in parentheses represent the percentage of ESAT-6 tetramer-binding CD4 T cells producing IFN-γ and the graph shows this value for each mouse and the mean ± SEM for each group. Significance was determined by two-tailed Student’s t test (**, P < 0.01). Data are representative of two independent experiments with four to five mice per group.
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fig2: ESAT-6–specific CD4 T cells produce IFN-γ in a TCR signaling–dependent manner. Mice were infected as described in Fig. 1. (A) Intracellular IFN-γ was assessed by flow cytometry directly ex vivo using lung cells (150 d after infection) processed in the presence of Brefeldin A. Gating strategy and representative flow cytometry plots for naive CD44low (gray), nontetramer-binding CD44hi (blue), and ESAT-6 tetramer-binding CD44hi (red) CD4 T cells are shown. (B) Flow cytometry plots show intracellular IFN-γ, or staining with isotype matched control, in ESAT-6–specific CD4 T cells (70 d after infection). Graph shows the percentage of ESAT-6 tetramer-binding or naive CD44low T cells producing IFN-γ at the indicated time points. (C) Mice infected with Mtb 35 d prior were treated intraperitoneally with either cyclosporine-A (CsA) or vehicle, and ESAT-6–specific cells in the lung were assessed for intracellular IFN-γ as in A and B. Numbers in parentheses represent the percentage of ESAT-6 tetramer-binding CD4 T cells producing IFN-γ and the graph shows this value for each mouse and the mean ± SEM for each group. Significance was determined by two-tailed Student’s t test (**, P < 0.01). Data are representative of two independent experiments with four to five mice per group.
Mentions: We detected IFN-γ in ESAT-6 tetramer-binding and CD44hi (but not CD44low) CD4 T cells (Fig. 2 A) using intracellular cytokine staining of T cells directly ex vivo without in vitro restimulation (Shafiani et al., 2013). At 16 d after infection, ~20% of ESAT-6–specific T cells recovered from the lungs produced IFN-γ, and this percentage gradually increased to ~40% on day 300 (Fig. 2 B). IFN-γ production was dependent on TCR signaling in at least half of these cells because administration of cyclosporine A (CsA; an inhibitor of proximal TCR-mediated signaling; Schreiber and Crabtree, 1992), 4 h before euthanasia blocked IFN-γ production in ~50% of the cells (Fig. 2 C). Collectively, our results indicate that ESAT-6 antigen is readily available for T cell recognition throughout infection and high numbers of ESAT-6–specific T cells are maintained in the lung in the presence of chronic antigenic stimulation.

Bottom Line: When transferred into uninfected animals, these cells persist, mount a robust recall response, and provide superior protection to Mtb rechallenge when compared to terminally differentiated Th1 cells that reside preferentially in the lung-associated vasculature.Thus, the molecular pathways required to maintain Mtb-specific CD4 T cells during ongoing infection are similar to those that maintain memory CD4 T cells in scenarios of antigen deprivation.These results suggest that vaccination strategies targeting the ICOS and Bcl6 pathways in CD4 T cells may provide new avenues to prevent TB.

View Article: PubMed Central - HTML - PubMed

Affiliation: Seattle Biomedical Research Institute (renamed Center for Infectious Disease Research), Seattle, WA 98109 Department of Immunology, University of Washington School of Medicine, Seattle, WA 98104.

Show MeSH
Related in: MedlinePlus