A2A adenosine receptors and C/EBPbeta are crucially required for IL-10 production by macrophages exposed to Escherichia coli.
We recently showed that A(2A) adenosine receptor activation by endogenous adenosine contributes to interleukin-10 (IL-10) production in polymicrobial sepsis. Here we investigated the molecular mechanisms underpinning this interaction between adenosine receptor signaling and infection by exposing macrophages to Escherichia coli. We demonstrated using receptor knockout mice that A(2A) receptor activation is critically required for the stimulatory effect of adenosine on IL-10 production by E coli-challenged macrophages, whereas A(2B) receptors have a minor role. The stimulatory effect of adenosine on E coli-induced IL-10 production did not require toll-like receptor 4 (TLR4) or MyD88, but was blocked by p38 inhibition. Using shRNA we demonstrated that TRAF6 impairs the potentiating effect of adenosine. Measuring IL-10 mRNA abundance and transfection with an IL-10 promoter-luciferase construct indicated that E coli and adenosine synergistically activate IL-10 transcription. Sequential deletion analysis and site-directed mutagenesis of the IL-10 promoter revealed that a region harboring C/EBP binding elements was responsible for the stimulatory effect of adenosine on E coli-induced IL-10 promoter activity. Adenosine augmented E coli-induced nuclear accumulation and DNA binding of C/EBPbeta. C/EBPbeta-deficient macrophages failed to produce IL-10 in response to adenosine and E coli. Our results suggest that the A(2A) receptor-C/EBPbeta axis is critical for IL-10 production after bacterial infection.
Csóka
Balázs
B
Department of Surgery, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA.
Németh
Zoltán H
ZH
Virág
László
L
Gergely
Pál
P
Leibovich
S Joseph
SJ
Pacher
Pál
P
Sun
Chun-Xiao
CX
Blackburn
Michael R
MR
Vizi
E Sylvester
ES
Deitch
Edwin A
EA
Haskó
György
G
D024506:5' Flanking Region / Q000235:genetics; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D004926:Escherichia coli / Q000502:physiology*; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D022782:CCAAT-Enhancer-Binding Protein-beta; D053594:Myeloid Differentiation Factor 88; D012333:RNA, Messenger; D043705:Receptor, Adenosine A2A; D048029:TNF Receptor-Associated Factor 6; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D016753:Interleukin-10; D048051:p38 Mitogen-Activated Protein Kinases; D000241:Adenosine