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Bacterial endotoxin induces IL-20 expression in the glial cells
Toru Hosoi1, Sachiyo Wada, Sawako Suzuki
1Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12, Nishi 6, Kita-Ku, Sapporo 060-0812, Japan.
Brain Research. Molecular Brain Research
|November 3, 2004
Summary
Bacterial lipopolysaccharide (LPS) triggers Interleukin-20 (IL-20) expression in glial cells via Myeloid differentiation factor 88 (MyD88) and p38 MAP kinase signaling. Glucocorticoids provide negative feedback, suggesting IL-20
Area of Science:
- Neuroimmunology
- Molecular Biology
- Cellular Signaling
Background:
- Interleukin-20 (IL-20) role in infection and brain inflammation is unclear.
- Regulatory mechanisms of IL-20 expression require elucidation.
Purpose of the Study:
- Investigate the signaling pathways regulating IL-20 expression induced by bacterial lipopolysaccharide (LPS).
- Determine the involvement of Myeloid differentiation factor 88 (MyD88) and p38 MAP kinase in LPS-induced IL-20 expression.
- Explore the role of glucocorticoids in regulating IL-20 expression.
Main Methods:
- Primary glial cell cultures and RAW264.7 macrophage cell line stimulation with LPS.
- Assessment of IL-20 expression using protein synthesis inhibitors (puromycin, cycloheximide).
- Analysis of LPS-induced IL-20 expression in MyD88-deficient glial cells.
- Inhibition of p38 MAP kinase activity using SB203580.
- Evaluation of dexamethasone's effect on LPS-induced IL-20 expression.
Main Results:
- LPS induced IL-20 expression in glial cells and macrophages, independent of de novo protein synthesis.
- LPS-induced IL-20 expression was completely abolished in MyD88-deficient glial cells.
- p38 MAP kinase inhibition significantly reduced LPS-induced IL-20 mRNA expression.
- LPS-induced p38 MAP kinase phosphorylation was delayed in MyD88-deficient cells.
- Dexamethasone inhibited LPS-induced IL-20 expression, indicating negative feedback.
Conclusions:
- LPS induces IL-20 expression through a MyD88-p38 MAP kinase-dependent pathway.
- Glucocorticoids negatively regulate IL-20 expression via a feedback loop.
- IL-20 likely plays a significant role in inflammatory responses within the brain.