Abstract
Signaling through the TLR family of molecular pattern recognition receptors has been implicated in the induction of innate and adaptive immune responses. A role for TLR signaling in the maintenance and/or regulation of Treg function has been proposed, however its functional relevance remains unclear. Here we have shown that TLR9 is highly expressed by human Treg secreting the antiinflammatory cytokine IL-10 induced following stimulation of blood and tissue CD3(+) T cells in the presence of 1 alpha,25-dihydroxyvitamin D3 (1 alpha 25VitD3), the active form of Vitamin D, with or without the glucocorticoid. dexamethasone. By contrast, TLR9 was not highly expressed by naturally occurring CD4(+)CD25(+) Treg or by Th1 and Th2 effector cells. Induction of TLR9, but not other TLRs, was IL-10 dependent and primarily regulated by 1a25VitD3 in vitro. Furthermore, ingestion of calcitriol (1 alpha 25VitD3) by human volunteers led to an increase of both IL-10 and TLR9 expression by CD3(+)CD4(+) T cells analyzed directly ex vivo. Stimulation of 1 alpha 25VitD3-induced IL-10-secreting Treg with TLR9 agonists, CpG oligonucleotides, resulted in decreased IL-10 and IFN-gamma synthesis and a concurrent loss of regulatory function, but, unexpectedly, increased IL-4 synthesis. We therefore suggest that TLR9 could be used to monitor and potentially modulate the function of 1 alpha 25VitD34nduced IL-10-secreting Treg in vivo, and that this has implications in cancer therapy and vaccine design.
Original language | English |
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Pages (from-to) | 387 - 398 |
Number of pages | 12 |
Journal | Journal of Clinical Investigation |
Volume | 119 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2 Feb 2009 |
Keywords
- Adult
- Aged
- Calcitriol
- Dexamethasone
- Humans
- Interleukin-10
- Male
- Middle Aged
- Oligodeoxyribonucleotides
- RNA, Messenger
- Receptors, Calcitriol
- T-Lymphocytes, Regulatory
- Toll-Like Receptor 9