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http://dx.doi.org/10.4110/in.2011.11.4.223

IGF-I Exerts an Anti-inflammatory Effect on Skeletal Muscle Cells through Down-regulation of TLR4 Signaling  

Lee, Won-Jun (Department of Exercise Science, College of Health Science, Ewha Womans University)
Publication Information
IMMUNE NETWORK / v.11, no.4, 2011 , pp. 223-226 More about this Journal
Abstract
Although exercise-induced growth factors such as Insulin-like growth factor-I (IGF-I) are known to affect various aspects of physiology in skeletal muscle cells, the molecular mechanism by which IGF-I modulates anti-inflammatory effects in these cells is presently unknown. Here, we showed that IGF-I stimulation suppresses the expression of toll-like receptor 4 (TLR4), a key innate immune receptor. A pharmacological inhibitor study further showed that PI3K/Akt signaling pathway is required for IGF-I-mediated negative regulation of TLR4 expression. Furthermore, IGF-I treatment reduced the expression of various NF-${\kappa}B$-target genes such as TNF-${\alpha}$ and IL-6. Taken together, these findings indicate that the anti-inflammatory effect of exercise may be due, at least in part, to IGF-I-induced suppression of TLR4 and subsequent downregulation of the TLR4-dependent inflammatory signaling pathway.
Keywords
Insulin-like growth factor-I; Toll-like receptor-4; Cytokines; Skeletal muscle cells; PI3K/Akt; MAPK;
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