Toll-like receptor control of glucocorticoid-induced apoptosis in human plasmacytoid predendritic cells (pDCs)

作者：Lepelletier, Yves; Zollinger, Raphael; Ghirelli, Cristina; Raynaud, Francoise; Hadj-Slimane, Reda; Cappuccio, Antonio; Hermine, Olivier; Liu, Yong-Jun; Soumelis, Vassili^*

来源：Blood, 2010, 116(18): 3389-3397.

DOI：10.1182/blood-2010-05-282913

• DENDRITIC CELLS
• GM-CSF
• ACTIVATION
• MECHANISMS
• CORTICOSTEROIDS
• PATHWAYS
• INHIBIT

Microbial infection triggers the endogenous production of immunosuppressive glucocorticoid (GC) hormones and simultaneously activates innate immunity through toll-like receptors (TLRs). How innate immune cells integrate these 2 opposing signals in dictating immunity or tolerance to infection is not known. In this study, we show that human plasmacytoid predendritic cells (pDCs) were highly sensitive to GC-induced apoptosis. Strikingly, they were protected by microbial stimulation through TLR-7 and TLR-9, but not by microbial-independent stimuli, such as interleukin-3, granulocyte macrophage colony-stimulating factor, or CD40-ligand. This protection was dependent on TLR-induced autocrine tumor necrosis factor-alpha and interferon-alpha, which collectively increased the expression ratio between antiapoptotic genes (Bcl-2, Bcl-xL, BIRC3, CFLAR) versus proapoptotic genes (Caspase-8, BID, BAD, BAX). In particular, virus-induced Bcl-2 up-regulation was dependent on autocrine interferon-alpha. Using small interfering RNA technology, we demonstrated that Bcl-2 and CFLAR/c-flip were essential for TLR-induced protection of pDCs from GC-induced caspase-8-mediated apoptosis. Our results demonstrate a novel property of the TLR pathway in regulating the interface between GC and innate immunity and reveal a previously undescribed mechanism of GC resistance. (Blood. 2010; 116(18):3389-3397)

• 出版日期2010-11-4