Limits...
Conventional T-bet(+)Foxp3(-) Th1 cells are the major source of host-protective regulatory IL-10 during intracellular protozoan infection.

Jankovic D, Kullberg MC, Feng CG, Goldszmid RS, Collazo CM, Wilson M, Wynn TA, Kamanaka M, Flavell RA, Sher A - J. Exp. Med. (2007)

Bottom Line: Unexpectedly, IFN-gamma-secreting T-bet(+)Foxp3(-) T helper type 1 (Th1) cells were found to be the major producers of IL-10 in these animals.Further analysis revealed that the same IL-10(+)IFN-gamma(gamma) population displayed potent effector function against the parasite while, paradoxically, also inducing profound suppression of IL-12 production by antigen-presenting cells.These findings indicate that IL-10 production by CD4(+) T lymphocytes need not involve a distinct regulatory Th cell subset but can be generated in Th1 cells as part of the effector response to intracellular pathogens.

View Article: PubMed Central - PubMed

Affiliation: Immunobiology Section and 2Immunopathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. DJankovic@niaid.nih.gov

ABSTRACT
Although interferon gamma (IFN-gamma) secretion is essential for control of most intracellular pathogens, host survival often also depends on the expression of interleukin 10 (IL-10), a cytokine known to counteract IFN-gamma effector functions. We analyzed the source of regulatory IL-10 in mice infected with the protozoan parasite Toxoplasma gondii. Unexpectedly, IFN-gamma-secreting T-bet(+)Foxp3(-) T helper type 1 (Th1) cells were found to be the major producers of IL-10 in these animals. Further analysis revealed that the same IL-10(+)IFN-gamma(gamma) population displayed potent effector function against the parasite while, paradoxically, also inducing profound suppression of IL-12 production by antigen-presenting cells. Although at any given time point only a fraction of the cells appeared to simultaneously produce IL-10 and IFN-gamma, IL-10 production could be stimulated in IL-10(-)IFN-gamma(+) cells by further activation in vitro. In addition, experiments with T. gondii-specific IL-10(+)IFN-gamma(+) CD4 clones revealed that although IFN-gamma expression is imprinted and triggered with similar kinetics regardless of the state of Th1 cell activation, IL-10 secretion is induced more rapidly from recently activated than from resting cells. These findings indicate that IL-10 production by CD4(+) T lymphocytes need not involve a distinct regulatory Th cell subset but can be generated in Th1 cells as part of the effector response to intracellular pathogens.

Show MeSH

Related in: MedlinePlus

Dual effector and regulatory functions of T. gondii–induced IL-10+IFN-γ+ CD4 T lymphocytes. CD4+CD44+ GFP− and CD4+CD44+ GFP+ lymphocytes were purified by FACS from spleens of day 7–infected IL-10 GFP knock-in tiger mice (A) and cultured at the indicated numbers with T. gondii–infected IL-10–deficient peritoneal macrophages. (B) At 24 h, supernatants were removed, [5,6-3H]Uracil was added for an additional 18 h, and isotope incorporation was measured as an index of parasite growth. Levels of IFN-γ and IL-10 were measured in culture supernatants by specific ELISA and NO quantitated by the Griess reaction. (C) In one set of cultures, control or anti–IL-10R mAb was added at the initiation of the experiment, and levels of IL-12p40 were measured in 24-h culture supernatants. Each data point is the mean of measurements performed on duplicate cultures (SD < 10%). The exp eriment shown in B is representative of three performed; the experiment in C is representative of two performed.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2118735&req=5

fig6: Dual effector and regulatory functions of T. gondii–induced IL-10+IFN-γ+ CD4 T lymphocytes. CD4+CD44+ GFP− and CD4+CD44+ GFP+ lymphocytes were purified by FACS from spleens of day 7–infected IL-10 GFP knock-in tiger mice (A) and cultured at the indicated numbers with T. gondii–infected IL-10–deficient peritoneal macrophages. (B) At 24 h, supernatants were removed, [5,6-3H]Uracil was added for an additional 18 h, and isotope incorporation was measured as an index of parasite growth. Levels of IFN-γ and IL-10 were measured in culture supernatants by specific ELISA and NO quantitated by the Griess reaction. (C) In one set of cultures, control or anti–IL-10R mAb was added at the initiation of the experiment, and levels of IL-12p40 were measured in 24-h culture supernatants. Each data point is the mean of measurements performed on duplicate cultures (SD < 10%). The exp eriment shown in B is representative of three performed; the experiment in C is representative of two performed.

Mentions: To determine whether the IL-10+IFN-γ+ CD4 T lymphocyte subpopulation can also express effector functions characteristic of Th1 cells, we tested their ability to control parasite growth when added to T. gondii–infected IL-10–deficient macrophages. To do so, we used IL-10gfp reporter mice, designated as tiger mice (31), in which an internal ribosome entry site GFP element was inserted into the 3′ region of the IL-10 gene, thus allowing us to isolate IL-10–producing cells ex vivo without subsequent manipulation (Fig. 6 A). As shown in Fig. 6 B, the CD4+CD44high GFP+ cells (which secreted IFN-γ and IL-10) were found to stimulate even better control of intracellular parasite proliferation than the CD4+CD44high GFP− fraction (which secreted IFN-γ alone). The restriction of parasite growth induced by either cell population correlated with the level of nitrite (NO) produced in the cultures (Fig. 6 B) and was inhibited by anti–IFN-γ mAb treatment (not depicted).


Conventional T-bet(+)Foxp3(-) Th1 cells are the major source of host-protective regulatory IL-10 during intracellular protozoan infection.

Jankovic D, Kullberg MC, Feng CG, Goldszmid RS, Collazo CM, Wilson M, Wynn TA, Kamanaka M, Flavell RA, Sher A - J. Exp. Med. (2007)

Dual effector and regulatory functions of T. gondii–induced IL-10+IFN-γ+ CD4 T lymphocytes. CD4+CD44+ GFP− and CD4+CD44+ GFP+ lymphocytes were purified by FACS from spleens of day 7–infected IL-10 GFP knock-in tiger mice (A) and cultured at the indicated numbers with T. gondii–infected IL-10–deficient peritoneal macrophages. (B) At 24 h, supernatants were removed, [5,6-3H]Uracil was added for an additional 18 h, and isotope incorporation was measured as an index of parasite growth. Levels of IFN-γ and IL-10 were measured in culture supernatants by specific ELISA and NO quantitated by the Griess reaction. (C) In one set of cultures, control or anti–IL-10R mAb was added at the initiation of the experiment, and levels of IL-12p40 were measured in 24-h culture supernatants. Each data point is the mean of measurements performed on duplicate cultures (SD < 10%). The exp eriment shown in B is representative of three performed; the experiment in C is representative of two performed.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2118735&req=5

fig6: Dual effector and regulatory functions of T. gondii–induced IL-10+IFN-γ+ CD4 T lymphocytes. CD4+CD44+ GFP− and CD4+CD44+ GFP+ lymphocytes were purified by FACS from spleens of day 7–infected IL-10 GFP knock-in tiger mice (A) and cultured at the indicated numbers with T. gondii–infected IL-10–deficient peritoneal macrophages. (B) At 24 h, supernatants were removed, [5,6-3H]Uracil was added for an additional 18 h, and isotope incorporation was measured as an index of parasite growth. Levels of IFN-γ and IL-10 were measured in culture supernatants by specific ELISA and NO quantitated by the Griess reaction. (C) In one set of cultures, control or anti–IL-10R mAb was added at the initiation of the experiment, and levels of IL-12p40 were measured in 24-h culture supernatants. Each data point is the mean of measurements performed on duplicate cultures (SD < 10%). The exp eriment shown in B is representative of three performed; the experiment in C is representative of two performed.
Mentions: To determine whether the IL-10+IFN-γ+ CD4 T lymphocyte subpopulation can also express effector functions characteristic of Th1 cells, we tested their ability to control parasite growth when added to T. gondii–infected IL-10–deficient macrophages. To do so, we used IL-10gfp reporter mice, designated as tiger mice (31), in which an internal ribosome entry site GFP element was inserted into the 3′ region of the IL-10 gene, thus allowing us to isolate IL-10–producing cells ex vivo without subsequent manipulation (Fig. 6 A). As shown in Fig. 6 B, the CD4+CD44high GFP+ cells (which secreted IFN-γ and IL-10) were found to stimulate even better control of intracellular parasite proliferation than the CD4+CD44high GFP− fraction (which secreted IFN-γ alone). The restriction of parasite growth induced by either cell population correlated with the level of nitrite (NO) produced in the cultures (Fig. 6 B) and was inhibited by anti–IFN-γ mAb treatment (not depicted).

Bottom Line: Unexpectedly, IFN-gamma-secreting T-bet(+)Foxp3(-) T helper type 1 (Th1) cells were found to be the major producers of IL-10 in these animals.Further analysis revealed that the same IL-10(+)IFN-gamma(gamma) population displayed potent effector function against the parasite while, paradoxically, also inducing profound suppression of IL-12 production by antigen-presenting cells.These findings indicate that IL-10 production by CD4(+) T lymphocytes need not involve a distinct regulatory Th cell subset but can be generated in Th1 cells as part of the effector response to intracellular pathogens.

View Article: PubMed Central - PubMed

Affiliation: Immunobiology Section and 2Immunopathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. DJankovic@niaid.nih.gov

ABSTRACT
Although interferon gamma (IFN-gamma) secretion is essential for control of most intracellular pathogens, host survival often also depends on the expression of interleukin 10 (IL-10), a cytokine known to counteract IFN-gamma effector functions. We analyzed the source of regulatory IL-10 in mice infected with the protozoan parasite Toxoplasma gondii. Unexpectedly, IFN-gamma-secreting T-bet(+)Foxp3(-) T helper type 1 (Th1) cells were found to be the major producers of IL-10 in these animals. Further analysis revealed that the same IL-10(+)IFN-gamma(gamma) population displayed potent effector function against the parasite while, paradoxically, also inducing profound suppression of IL-12 production by antigen-presenting cells. Although at any given time point only a fraction of the cells appeared to simultaneously produce IL-10 and IFN-gamma, IL-10 production could be stimulated in IL-10(-)IFN-gamma(+) cells by further activation in vitro. In addition, experiments with T. gondii-specific IL-10(+)IFN-gamma(+) CD4 clones revealed that although IFN-gamma expression is imprinted and triggered with similar kinetics regardless of the state of Th1 cell activation, IL-10 secretion is induced more rapidly from recently activated than from resting cells. These findings indicate that IL-10 production by CD4(+) T lymphocytes need not involve a distinct regulatory Th cell subset but can be generated in Th1 cells as part of the effector response to intracellular pathogens.

Show MeSH
Related in: MedlinePlus