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Expansion and function of Foxp3-expressing T regulatory cells during tuberculosis.

Scott-Browne JP, Shafiani S, Tucker-Heard G, Ishida-Tsubota K, Fontenot JD, Rudensky AY, Bevan MJ, Urdahl KB - J. Exp. Med. (2007)

Bottom Line: In the Mtb-infected lung, T reg cells accumulate in high numbers in all sites where CD4(+) T cells are found, including perivascular/peribronchiolar regions and within lymphoid aggregates of granulomas.When T reg cells were depleted by administration of anti-Thy1.1 before aerosol infection with Mtb, we observed approximately 1 log less of colony-forming units of Mtb in the lungs.Thus, after aerosol infection, T reg cells proliferate and accumulate at sites of infection, and have the capacity to suppress immune responses that contribute to the control of Mtb.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Mycobacterium tuberculosis (Mtb) frequently establishes persistent infections that may be facilitated by mechanisms that dampen immunity. T regulatory (T reg) cells, a subset of CD4(+) T cells that are essential for preventing autoimmunity, can also suppress antimicrobial immune responses. We use Foxp3-GFP mice to track the activity of T reg cells after aerosol infection with Mtb. We report that during tuberculosis, T reg cells proliferate in the pulmonary lymph nodes (pLNs), change their cell surface phenotype, and accumulate in the pLNs and lung at a rate parallel to the accumulation of effector T cells. In the Mtb-infected lung, T reg cells accumulate in high numbers in all sites where CD4(+) T cells are found, including perivascular/peribronchiolar regions and within lymphoid aggregates of granulomas. To determine the role of T reg cells in the immune response to tuberculosis, we generated mixed bone marrow chimeric mice in which all cells capable of expressing Foxp3 expressed Thy1.1. When T reg cells were depleted by administration of anti-Thy1.1 before aerosol infection with Mtb, we observed approximately 1 log less of colony-forming units of Mtb in the lungs. Thus, after aerosol infection, T reg cells proliferate and accumulate at sites of infection, and have the capacity to suppress immune responses that contribute to the control of Mtb.

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Reduced Mtb CFU in lungs of T reg cell–depleted mice. (A and B) CFU analysis was performed 23 d after infection in Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice in the spleen (A) or lung (B), as indicated. CFU counts from each organ were determined from 10-fold serial dilutions, and the numbers of viable bacteria are shown for each mouse from two independent experiments (**, P < 0.01; *, P < 0.05). The limit of detection for these experiments was 100 CFU per organ and is indicated on the graph by the dotted line. (C) Analysis of IFN-γ production by CD4+ cells from lungs or pLNs from mock or depleted [KO:WT] chimeras. Data represent analysis of pooled lung cells from all mice in each group, or, in the case of pLNs, from individual mice, representative of each group. Percentage of IFN-γ–producing cells (gated on CD4+ cells) is shown after in vitro restimulation with media alone, PMA/ionomycin, or ESAT61-20 peptide. (D) IFN-γ production by CD4+ cells in the pLN. The percentage of pLN CD4+ T cells producing IFN-γ after in vitro restimulation with media alone, ESAT61-20 peptide, or PMA/ionomycin. Using the same gates shown in C, data from each individual mouse 23 d after infection from Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice are represented.
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fig6: Reduced Mtb CFU in lungs of T reg cell–depleted mice. (A and B) CFU analysis was performed 23 d after infection in Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice in the spleen (A) or lung (B), as indicated. CFU counts from each organ were determined from 10-fold serial dilutions, and the numbers of viable bacteria are shown for each mouse from two independent experiments (**, P < 0.01; *, P < 0.05). The limit of detection for these experiments was 100 CFU per organ and is indicated on the graph by the dotted line. (C) Analysis of IFN-γ production by CD4+ cells from lungs or pLNs from mock or depleted [KO:WT] chimeras. Data represent analysis of pooled lung cells from all mice in each group, or, in the case of pLNs, from individual mice, representative of each group. Percentage of IFN-γ–producing cells (gated on CD4+ cells) is shown after in vitro restimulation with media alone, PMA/ionomycin, or ESAT61-20 peptide. (D) IFN-γ production by CD4+ cells in the pLN. The percentage of pLN CD4+ T cells producing IFN-γ after in vitro restimulation with media alone, ESAT61-20 peptide, or PMA/ionomycin. Using the same gates shown in C, data from each individual mouse 23 d after infection from Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice are represented.

Mentions: The bacterial loads were compared between depleted infected experimental chimeras and mock-depleted experimental chimeras. The bacterial load in the spleen showed no statistical difference between the two groups (Fig. 6 A); however, the lungs displayed lower CFU values after depletion of T cells capable of expressing Foxp3 (∼0.9 log CFU less in experiment 1 and ∼1.1 log CFU less in experiment 2; Fig. 6 B). The lower CFU in T reg cell–depleted chimeras was correlated with a higher percentage of activated T cells in the lung (Fig. 5 C) with the capacity to rapidly produce IFN-γ in response to polyclonal stimulation (∼17% of CD4+ T cells in the depleted lungs produced IFN-γ after stimulation with PMA and ionomycin, compared with only ∼9% in the mock-depleted lungs; Fig. 6 C). However, the number of effector T cells producing IFN-γ in response to the MHC class II–restricted, Mtb-specific peptide, ESAT-61-20 was not increased in either the lung or the pLN (Fig. 6 C and D), probably because the reduced bacterial load resulted in reduced stimulation of T cells specific for this peptide. Overall, these results demonstrate that T reg cells have the capacity to suppress immune responses that control Mtb, especially in the lung.


Expansion and function of Foxp3-expressing T regulatory cells during tuberculosis.

Scott-Browne JP, Shafiani S, Tucker-Heard G, Ishida-Tsubota K, Fontenot JD, Rudensky AY, Bevan MJ, Urdahl KB - J. Exp. Med. (2007)

Reduced Mtb CFU in lungs of T reg cell–depleted mice. (A and B) CFU analysis was performed 23 d after infection in Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice in the spleen (A) or lung (B), as indicated. CFU counts from each organ were determined from 10-fold serial dilutions, and the numbers of viable bacteria are shown for each mouse from two independent experiments (**, P < 0.01; *, P < 0.05). The limit of detection for these experiments was 100 CFU per organ and is indicated on the graph by the dotted line. (C) Analysis of IFN-γ production by CD4+ cells from lungs or pLNs from mock or depleted [KO:WT] chimeras. Data represent analysis of pooled lung cells from all mice in each group, or, in the case of pLNs, from individual mice, representative of each group. Percentage of IFN-γ–producing cells (gated on CD4+ cells) is shown after in vitro restimulation with media alone, PMA/ionomycin, or ESAT61-20 peptide. (D) IFN-γ production by CD4+ cells in the pLN. The percentage of pLN CD4+ T cells producing IFN-γ after in vitro restimulation with media alone, ESAT61-20 peptide, or PMA/ionomycin. Using the same gates shown in C, data from each individual mouse 23 d after infection from Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice are represented.
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fig6: Reduced Mtb CFU in lungs of T reg cell–depleted mice. (A and B) CFU analysis was performed 23 d after infection in Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice in the spleen (A) or lung (B), as indicated. CFU counts from each organ were determined from 10-fold serial dilutions, and the numbers of viable bacteria are shown for each mouse from two independent experiments (**, P < 0.01; *, P < 0.05). The limit of detection for these experiments was 100 CFU per organ and is indicated on the graph by the dotted line. (C) Analysis of IFN-γ production by CD4+ cells from lungs or pLNs from mock or depleted [KO:WT] chimeras. Data represent analysis of pooled lung cells from all mice in each group, or, in the case of pLNs, from individual mice, representative of each group. Percentage of IFN-γ–producing cells (gated on CD4+ cells) is shown after in vitro restimulation with media alone, PMA/ionomycin, or ESAT61-20 peptide. (D) IFN-γ production by CD4+ cells in the pLN. The percentage of pLN CD4+ T cells producing IFN-γ after in vitro restimulation with media alone, ESAT61-20 peptide, or PMA/ionomycin. Using the same gates shown in C, data from each individual mouse 23 d after infection from Thy1.1-depleted (filled diamonds) or mock-depleted (open diamonds) mice are represented.
Mentions: The bacterial loads were compared between depleted infected experimental chimeras and mock-depleted experimental chimeras. The bacterial load in the spleen showed no statistical difference between the two groups (Fig. 6 A); however, the lungs displayed lower CFU values after depletion of T cells capable of expressing Foxp3 (∼0.9 log CFU less in experiment 1 and ∼1.1 log CFU less in experiment 2; Fig. 6 B). The lower CFU in T reg cell–depleted chimeras was correlated with a higher percentage of activated T cells in the lung (Fig. 5 C) with the capacity to rapidly produce IFN-γ in response to polyclonal stimulation (∼17% of CD4+ T cells in the depleted lungs produced IFN-γ after stimulation with PMA and ionomycin, compared with only ∼9% in the mock-depleted lungs; Fig. 6 C). However, the number of effector T cells producing IFN-γ in response to the MHC class II–restricted, Mtb-specific peptide, ESAT-61-20 was not increased in either the lung or the pLN (Fig. 6 C and D), probably because the reduced bacterial load resulted in reduced stimulation of T cells specific for this peptide. Overall, these results demonstrate that T reg cells have the capacity to suppress immune responses that control Mtb, especially in the lung.

Bottom Line: In the Mtb-infected lung, T reg cells accumulate in high numbers in all sites where CD4(+) T cells are found, including perivascular/peribronchiolar regions and within lymphoid aggregates of granulomas.When T reg cells were depleted by administration of anti-Thy1.1 before aerosol infection with Mtb, we observed approximately 1 log less of colony-forming units of Mtb in the lungs.Thus, after aerosol infection, T reg cells proliferate and accumulate at sites of infection, and have the capacity to suppress immune responses that contribute to the control of Mtb.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Mycobacterium tuberculosis (Mtb) frequently establishes persistent infections that may be facilitated by mechanisms that dampen immunity. T regulatory (T reg) cells, a subset of CD4(+) T cells that are essential for preventing autoimmunity, can also suppress antimicrobial immune responses. We use Foxp3-GFP mice to track the activity of T reg cells after aerosol infection with Mtb. We report that during tuberculosis, T reg cells proliferate in the pulmonary lymph nodes (pLNs), change their cell surface phenotype, and accumulate in the pLNs and lung at a rate parallel to the accumulation of effector T cells. In the Mtb-infected lung, T reg cells accumulate in high numbers in all sites where CD4(+) T cells are found, including perivascular/peribronchiolar regions and within lymphoid aggregates of granulomas. To determine the role of T reg cells in the immune response to tuberculosis, we generated mixed bone marrow chimeric mice in which all cells capable of expressing Foxp3 expressed Thy1.1. When T reg cells were depleted by administration of anti-Thy1.1 before aerosol infection with Mtb, we observed approximately 1 log less of colony-forming units of Mtb in the lungs. Thus, after aerosol infection, T reg cells proliferate and accumulate at sites of infection, and have the capacity to suppress immune responses that contribute to the control of Mtb.

Show MeSH
Related in: MedlinePlus