TLR4/MYD88-dependent, LPS-induced synthesis of PGE2 by macrophages or dendritic cells prevents anti-CD3-mediated CD95L upregulation in T cells.
Antigen-presenting cells (APCs) control T-cell responses by multiple mechanisms, including the expression of co-stimulatory molecules and the production of cytokines and other mediators that control T-cell proliferation, survival and differentiation. Here, we demonstrate that soluble factor(s) produced by Toll-like receptor (TLR)-activated APCs suppress activation-induced cell death (AICD). This effect was observed in non-stimulated APCs, but it was significantly increased after lipopolysaccharide (LPS) treatment. Using different KO mice, we found that the LPS-induced protective factor is dependent on TLR4/MyD88. We identified the protective factor as prostaglandin E(2) (PGE(2)) and showed that both APC-derived supernatants and PGE(2) prevented CD95L upregulation in T cells in response to TCR/CD3 stimulation, thereby avoiding both AICD and activated T cell killing of target macrophages. The PGE(2) receptors, EP2 and EP4, appear to be involved since pharmacological stimulation of these receptors mimics the protective effect on T cells and their respective antagonists interfere with the protection induced by either APCs derived or synthetic PGE(2). Finally, the engagement of EP2 and EP4 synergistically activates protein kinase A (PKA) and exchange protein directly activated by cAMP pathways to prevent AICD. Taken together, these results indicate that APCs can regulate T-cell levels of CD95L by releasing PGE(2) in response to LPS through a TLR4/MyD88-dependent pathway, with consequences for both T cell and their own survival.
Weinlich
R
R
Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
Bortoluci
K R
KR
Chehab
C F
CF
Serezani
C H
CH
Ulbrich
A G
AG
Peters-Golden
M
M
Russo
M
M
Amarante-Mendes
G P
GP
D000818:Animals; D017252:CD3 Complex / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis*; D053222:Fas Ligand Protein / Q000235:genetics* / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000378:metabolism; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D015398:Signal Transduction / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D017252:CD3 Complex; C482601:Epac protein, mouse; D053222:Fas Ligand Protein; D020662:Guanine Nucleotide Exchange Factors; D008070:Lipopolysaccharides; D053594:Myeloid Differentiation Factor 88; C545645:Ptger2 protein, mouse; C545651:Ptger4 protein, mouse; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D051197:Toll-Like Receptor 4; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone