Molecular mechanisms of the induction of IL-12 and its inhibition by IL-10.
Exogenously added IL-10 rapidly inhibited Staphylococcus aureus- or LPS-induced cytokine mRNA expression in human PBMCs and monocytes, with a maximal effect observed when IL-10 was added from 20 h before until 1 h after the addition of the inducers. Nuclear run-on assays revealed that the inhibition of IL-12 p40, IL-12 p35, and TNF-alpha was at the gene transcriptional level and that the addition of IL-10 to S. aureus- or LPS-treated PBMCs did not affect mRNA stability. The inhibitory activity of IL-10 was abrogated by cycloheximide (CHX), suggesting the involvement of a newly synthesized protein(s). The addition of CHX at 2 h before S. aureus or LPS also inhibited the accumulation of IL-12 p40 mRNA, but did not inhibit IL-12 p35 and TNF-alpha mRNA. This finding suggests that p40 transcription is regulated through a de novo synthesized protein factor(s), whereas the addition of CHX at 2 h after S. aureus activation caused superinduction of the IL-12 p40, IL-12 p35, and TNF-alpha genes. These results indicate that in human monocytes, the mechanism(s) of IL-10 suppression of both IL-12 p40 and IL-12 p35 genes is primarily seen at the transcriptional level, and that the induction of the IL-12 p40 and p35 genes have different requirements for de novo protein synthesis.
Aste-Amezaga
M
M
The Wistar Institute of Anatomy and Biology, Philadelphia, PA 19104, USA.
Ma
X
X
Sartori
A
A
Trinchieri
G
G
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D018664:Interleukin-12 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000235:genetics; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013211:Staphylococcus aureus; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D008070:Lipopolysaccharides; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12; D003513:Cycloheximide