Dataset Information

3-hydroxykynurenine suppresses CD4+ T-cell proliferation, induces T-regulatory-cell development, and prolongs corneal allograft survival.

ABSTRACT:

Purpose

IDO (indoleamine 2,3-dioxygenase) modulates the immune response by depletion of the essential amino acid tryptophan, and IDO overexpression has been shown to prolong corneal allograft survival. This study was conducted to examine the effect of kynurenines, the products of tryptophan breakdown and known to act directly on T lymphocytes, on corneal graft survival.

Methods

The effects of kynurenines on T-cell proliferation and death, T-regulatory-cell development, and dendritic cell function, phenotype, and viability were analyzed in vitro. The effect of topical and systemic administration of 3-hydroxykynurenine (3HK) on orthotopic murine corneal allograft survival was examined.

Results

T-lymphocyte proliferation was inhibited by two of the four different kynurenines: 3HK and 3-hydroxyanthranilic acid (3HAA). This effect was accompanied by significant T-cell death. Neither 3HK nor 3HAA altered dendritic cell function, nor did they induce apoptosis or pathogenicity to corneal endothelial cells. Administration of systemic and topical 3HK to mice receiving a fully mismatched corneal graft resulted in significant prolongation of graft survival (median survival of control grafts, 12 days; of treated, 19 and 15 days, respectively; P < 0.0003). While systemic administration of 3HK was associated with a significant depletion of CD4(+) T, CD8(+) T, and B lymphocytes in peripheral blood, no depletion was found after topical administration.

Conclusions

The production of kynurenines, in particular 3HK and 3HAA, may be one mechanism (in addition to tryptophan depletion) by which IDO prolongs graft survival. These molecules have potential as specific agents for preventing allograft rejection in patients at high rejection risk.

SUBMITTER: Zaher SS

PROVIDER: S-EPMC3088555 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Publications

3-hydroxykynurenine suppresses CD4+ T-cell proliferation, induces T-regulatory-cell development, and prolongs corneal allograft survival.

Zaher Sarah S SS Germain Conrad C Fu Hongmei H Larkin Daniel F P DF George Andrew J T AJ

Investigative ophthalmology & visual science 20110422 5

<h4>Purpose</h4>IDO (indoleamine 2,3-dioxygenase) modulates the immune response by depletion of the essential amino acid tryptophan, and IDO overexpression has been shown to prolong corneal allograft survival. This study was conducted to examine the effect of kynurenines, the products of tryptophan breakdown and known to act directly on T lymphocytes, on corneal graft survival.<h4>Methods</h4>The effects of kynurenines on T-cell proliferation and death, T-regulatory-cell development, and dendrit ...[more]

PMID: 21212175

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Project description:Due to vigorous alloimmunity, an allograft is usually rejected without any conventional immunosuppressive treatment. However, continuous global immunosuppression may cause severe side effects, including tumors and infections. Mounting evidence has shown that cyclosporine (CsA), a common immunosuppressant used in clinic, impedes allograft tolerance by dampening regulatory T cells (Tregs), although it inhibits allograft rejection at the same time. Therefore, it is necessary to seek an alternative immunosuppressive drug that spares Tregs with high efficiency in suppression but low toxicity. In this study, we investigated the capacity of emodin, an anthraquinone molecule originally extracted from certain natural plants, to prolong transplant survival in a mouse model and explored the cellular and molecular mechanisms underlying its action. We found that emodin significantly extended skin allograft survival and hindered CD3+ T cell infiltration in the allograft, accompanied by an increase in CD4+Foxp3+ and CD8+CD122+ Treg frequencies and numbers but a reduction in effector CD8+CD44highCD62Llow T cells in recipient mice. Emodin also inhibited effector CD8+ T cells proliferation in vivo. However, CD4+CD25+, but not CD8+CD122+, Tregs derived from emodin-treated recipients were more potent in suppression of allograft rejection than those isolated from control recipients, suggesting that emodin also enhances the suppressive function of CD4+CD25+ Tregs. Interestingly, depleting CD25+ Tregs largely reversed skin allograft survival prolonged by emodin while depleting CD122+ Tregs only partially abrogated the same allograft survival. Furthermore, we found that emodin hindered dendritic cell (DC) maturation and reduced alloantibody production posttransplantation. Finally, we demonstrated that emodin inhibited in vitro proliferation of T cells and blocked their mTOR signaling as well. Therefore, emodin may be a novel mTOR inhibitor that suppresses alloimmunity by inducing both CD4+FoxP3+ and CD8+CD122+ Tregs, suppressing alloantibody production, and hindering DC maturation. Thus, emodin is a newly emerging immunosuppressant and could be utilized in clinical transplantation in the future.

Dataset Information

3-hydroxykynurenine suppresses CD4+ T-cell proliferation, induces T-regulatory-cell development, and prolongs corneal allograft survival.

Purpose

Methods

Results

Conclusions

Publications

3-hydroxykynurenine suppresses CD4+ T-cell proliferation, induces T-regulatory-cell development, and prolongs corneal allograft survival.

Similar Datasets

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