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Inhibition of allogeneic T cell proliferation by indoleamine 2,3-dioxygenase-expressing dendritic cells: mediation of suppression by tryptophan metabolites.

Terness P, Bauer TM, Röse L, Dufter C, Watzlik A, Simon H, Opelz G - J. Exp. Med. (2002)

Bottom Line: Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro.Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive.Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Department of Transplantation Immunology, University of Heidelberg, 69120 Heidelberg, Germany. peter_terness@med.uni-heidelberg.de

ABSTRACT
Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, is expressed in certain cells and tissues, particularly in antigen-presenting cells of lymphoid organs and in the placenta. It was shown that IDO prevents rejection of the fetus during pregnancy, probably by inhibiting alloreactive T cells, and it was suggested that IDO-expression in antigen-presenting cells may control autoreactive immune responses. Degradation of tryptophan, an essential amino acid required for cell proliferation, was reported to be the mechanism of IDO-induced T cell suppression. Because we wanted to study the action of IDO-expressing dendritic cells (DCs) on allogeneic T cells, the human IDO gene was inserted into an adenoviral vector and expressed in DCs. Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro. Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive. T cells, once stopped in their proliferation, could not be restimulated. Inhibition of proliferation was likely due to T cell death because suppressive tryptophan catabolites exerted a cytotoxic action on CD3(+) cells. This action preferentially affected activated T cells and increased gradually with exposure time. In addition to T cells, B and natural killer (NK) cells were also killed, whereas DCs were not affected. Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.

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Induction of cell death by tryptophan metabolites. Lymphocytes were stimulated with anti-CD3 in the presence or absence (control) of active metabolites (1,501 μM kynurenine, 349 μM 3-hydroxykynurenine, 510 μM 3-hydroxyanthranilic acid) or a metabolite mixture (kynurenine plus 3-hydroxykynurenine plus anthranilic acid plus 3-hydroxyanthranilic acid plus quinolinic acid)(64 μM of each compound). After 3 d the cells were washed, stained with anti-CD3-FITC antibody and 7-AAD. The percentages of dead (7-AAD-positive) T cells was determined in FACScan™. A shows the lymphocyte gate. B–F show the percentage of dead cells in the negative control and after treatment with kynurenine, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, or metabolite mixture.
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fig9: Induction of cell death by tryptophan metabolites. Lymphocytes were stimulated with anti-CD3 in the presence or absence (control) of active metabolites (1,501 μM kynurenine, 349 μM 3-hydroxykynurenine, 510 μM 3-hydroxyanthranilic acid) or a metabolite mixture (kynurenine plus 3-hydroxykynurenine plus anthranilic acid plus 3-hydroxyanthranilic acid plus quinolinic acid)(64 μM of each compound). After 3 d the cells were washed, stained with anti-CD3-FITC antibody and 7-AAD. The percentages of dead (7-AAD-positive) T cells was determined in FACScan™. A shows the lymphocyte gate. B–F show the percentage of dead cells in the negative control and after treatment with kynurenine, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, or metabolite mixture.

Mentions: The lack of restimulation of kynurenine-suppressed T cells might be attributable to either T cell areactivity or cell death. To analyze the underlying mechanism, the cells were stimulated as described in the presence of suppressive amounts of kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, or a mixture of all metabolites for 3 d, and cell viability was determined in FACS® by vital staining with 7-AAD. As shown in Fig. 9 , virtually all cells died at suppressive concentrations of single components or the metabolite mixture.


Inhibition of allogeneic T cell proliferation by indoleamine 2,3-dioxygenase-expressing dendritic cells: mediation of suppression by tryptophan metabolites.

Terness P, Bauer TM, Röse L, Dufter C, Watzlik A, Simon H, Opelz G - J. Exp. Med. (2002)

Induction of cell death by tryptophan metabolites. Lymphocytes were stimulated with anti-CD3 in the presence or absence (control) of active metabolites (1,501 μM kynurenine, 349 μM 3-hydroxykynurenine, 510 μM 3-hydroxyanthranilic acid) or a metabolite mixture (kynurenine plus 3-hydroxykynurenine plus anthranilic acid plus 3-hydroxyanthranilic acid plus quinolinic acid)(64 μM of each compound). After 3 d the cells were washed, stained with anti-CD3-FITC antibody and 7-AAD. The percentages of dead (7-AAD-positive) T cells was determined in FACScan™. A shows the lymphocyte gate. B–F show the percentage of dead cells in the negative control and after treatment with kynurenine, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, or metabolite mixture.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196057&req=5

fig9: Induction of cell death by tryptophan metabolites. Lymphocytes were stimulated with anti-CD3 in the presence or absence (control) of active metabolites (1,501 μM kynurenine, 349 μM 3-hydroxykynurenine, 510 μM 3-hydroxyanthranilic acid) or a metabolite mixture (kynurenine plus 3-hydroxykynurenine plus anthranilic acid plus 3-hydroxyanthranilic acid plus quinolinic acid)(64 μM of each compound). After 3 d the cells were washed, stained with anti-CD3-FITC antibody and 7-AAD. The percentages of dead (7-AAD-positive) T cells was determined in FACScan™. A shows the lymphocyte gate. B–F show the percentage of dead cells in the negative control and after treatment with kynurenine, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, or metabolite mixture.
Mentions: The lack of restimulation of kynurenine-suppressed T cells might be attributable to either T cell areactivity or cell death. To analyze the underlying mechanism, the cells were stimulated as described in the presence of suppressive amounts of kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, or a mixture of all metabolites for 3 d, and cell viability was determined in FACS® by vital staining with 7-AAD. As shown in Fig. 9 , virtually all cells died at suppressive concentrations of single components or the metabolite mixture.

Bottom Line: Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro.Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive.Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Department of Transplantation Immunology, University of Heidelberg, 69120 Heidelberg, Germany. peter_terness@med.uni-heidelberg.de

ABSTRACT
Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, is expressed in certain cells and tissues, particularly in antigen-presenting cells of lymphoid organs and in the placenta. It was shown that IDO prevents rejection of the fetus during pregnancy, probably by inhibiting alloreactive T cells, and it was suggested that IDO-expression in antigen-presenting cells may control autoreactive immune responses. Degradation of tryptophan, an essential amino acid required for cell proliferation, was reported to be the mechanism of IDO-induced T cell suppression. Because we wanted to study the action of IDO-expressing dendritic cells (DCs) on allogeneic T cells, the human IDO gene was inserted into an adenoviral vector and expressed in DCs. Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro. Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive. T cells, once stopped in their proliferation, could not be restimulated. Inhibition of proliferation was likely due to T cell death because suppressive tryptophan catabolites exerted a cytotoxic action on CD3(+) cells. This action preferentially affected activated T cells and increased gradually with exposure time. In addition to T cells, B and natural killer (NK) cells were also killed, whereas DCs were not affected. Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.

Show MeSH
Related in: MedlinePlus