Differential regulation of astrocyte TNF-alpha expression by the cytokines TGF-beta, IL-6 and IL-10.
In this study, we demonstrate that transforming growth factor-beta (TGF-beta), interleukin-10 (IL-10) and interleukin-6 (IL-6) inhibit tumor necrosis factor-alpha expression by primary rat astrocytes. Treatment of astrocytes with TGF-beta alone had no effect on TNF-alpha expression, however, TGF-beta suppressed induction of TNF-alpha expression at both the protein and mRNA level. In contrast, IL-10 and IL-6 both inhibited TNF-alpha protein expression by astrocytes, but had no effect on mRNA levels. The extent of IL-6-mediated inhibition was greatest when astrocytes were pretreated with IL-6 for 12-24 hr, then exposed to the inducing stimuli, while IL-10 was an effective inhibitor even when added simultaneously with the inducing stimuli. Collectively, these data indicate that TGF-beta, IL-6 and IL-10 are all capable of inhibiting TNF-alpha expression by astrocytes, although these immunosuppressive cytokines act at different levels of gene expression; i.e. TGF-beta at the transcriptional level and IL-10/IL-6 at the translational level. These results indicate that TGF-beta, IL-6 and IL-10 are important regulators of cytokine production by astrocytes under inflammatory conditions in the brain, and can contribute to controlling the production of detrimental cytokines such as TNF-alpha.
Benveniste
E N
EN
Department of Cell Biology, University of Alabama at Birmingham 35294-0005, USA.
Tang
L P
LP
Law
R M
RM
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D003864:Depression, Chemical; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D012313:RNA / Q000302:isolation & purification / Q000378:metabolism; D015347:RNA Probes; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D015850:Interleukin-6; D015347:RNA Probes; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D012313:RNA; D012260:Ribonucleases