성상교세포에서 옥시스테롤의 항염증반응에 대한 연구
Anti-Inflammatory Mechanism By Oxysterols In Cultured Rat Brain Astrocytes
- 주제(키워드) oxysterols + LXR + iNOS + IFN-gamma + STAT + IRF-1 + astrocytes
- 발행기관 아주대학교
- 지도교수 주일로
- 발행년도 2006
- 학위수여년월 2006. 2
- 학위명 석사
- 학과 및 전공 일반대학원 의학과
- 본문언어 영어
초록/요약
Cholesterols are enriched in the brain and can be oxidized to oxysterols by spontaneous or enzyme-mediated processes. Oxysterols are transport forms of cholesterols across cell membranes and the blood-brain barrier. Here, to elucidate the roles of oxysterols in brain inflammation, I treated lipopolysaccharides(LPS)- or interferon gamma(IFN-stimulated rat brain astrocytes with two oxysterols, 7-ketocholesterol and 22(R)-hydroxycholesterol. In LPS-stimulated astrocytes, both oxysterols suppressed inducible nitric oxide synthase expression and nitric oxide release as well as upstream signaling molecules including interferon-, phosphorylated signal transducer and activator of transcription 1/3, and interferon regulatory factor-1. And oxysterols also inhibited interleukin-6 and tumor necrosis factor  transcripts, and monocyte chemoattractant protein-1 release. Oxysterols are known as nuclear receptor liver X receptor agonists, and these inhibitory effects were observed with synthetic agonists of liver X receptor and retinoid X receptor in a similar manner. In addition, ATP-binding cassette transporter a1 transcription, LXR-induced target gene, was increased by addition of either oxysterol or LXR agonist. Thus, I conclude that these effects are mediated by LXR/RXR heterodimers. Next, these inhibitory effects of oxysterols also appeared and were potentiated by RXR agonist in IFN-stimulated astrocytes. Furthermore, iNOS expression was inhibited by oxysterols and synthetic LXR ligands in LPS-stimulated primary microglia as well as in LPS- or IFN-stimulated primary astrocytes. I conclude that oxysterols suppress inflammatory gene expression through LXR/RXR activation in activated rat brain glial cells and these results provide new insights into the roles of oxysterols in brain inflammation.
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ABSTRACT ⅰ
TABLE OF CONTENTS ⅲ
LIST OF FIGURES ⅴ
LIST OF TABLES ⅵ
ABBREVIATION ⅶ
I. INTRODUCTION 1
A. Cholesterol in brain 1
B. Oxysterol metabolism 3
C. LXRs in cholesterol metabolism and inflammation 5
D. Aims of study 7
II. MATERIALS AND METHODS 8
A. Reagents 8
B. Cell culture 8
C. Western Blot Analysis 9
D. Determination of NO release 9
E. Reverse transcription-polymerase chain reaction (RT-PCR) 10
F. Enzyme-linked immunosorbent assay (ELISA) 10
G. Data analysis 11
III. RESULTS 12
A. Oxysterols suppress iNOS, COX2 expression and NO production in
LPS-stimulated rat brain astrocytes. 12
B. Suppression of iNOS expression by oxysterols occurs in a LXR/RXR
heterodimer-dependent manner. 15
C. Oxysterols and synthetic LXR agonists suppress the expression of IFN-
transcripts, phosphorylated STATs, and IRF-1 expression in LPS-
stimulated primary astrocytes. 18
D. Oxysterols and synthetic LXR agonists suppress not only iNOS expression
but the expression of IL-6 and TNFtranscripts, and MCP-1 release
in LPS-stimulated primary astrocytes. 20
E. Oxysterols and synthetic LXR agonists suppress also iNOS expression
in IFN-stimulated primary astrocytes and LPS-stimulated primary
microglia 23
IV. DISCUSSION 27
V. CONCLUSION 29
REFERENCES 30
국문요약 39
