Effect Of PPARγ On THP-1 Macrophage CD36 Expression And Cholesterol Influx

CD36, the class B scavenger receptor , is identified as the major receptor for oxidized low density lipoprotein(oxLDL). Macrophage scavenger receptors are thought to play a significant role in atherosclerotic foam cell development because of their ability to bind and internalize oxLDL. Peroxisome proliferator-activated receptor gamma (PPARγ ) is a member of nuclear hormone superfamily. PPAR y has been implicated in such diverse pathways as lipid metabolism and glucose homeostasis, promoting adipocyte, monocyte/macrophage differentiation, inhibiting inflammation, subsequently contributing to the development of atherosclerosis. The interest has focused on the role of PPAR Y in modulating macrophage cholesterol and lipid homeostasis. In this study, firstly, we investigated whether CD36 and PPAR y participated in the progression of atherosclerosis; Secondly THP-1 macrophage were incubated with the oxLDL different hours to investigate the effects of oxLDL on CD36 expression and cellular cholesterol influx; Finally using PPARγ agonist (ciglitazone) and antisense PPARy oligonucleotide to study the effect of PPARγ on CD36 expression and cellular cholesterol influx. It just provide an evidence to elucidate the possible mechanism of PPARγ on THP-1 macrophage CD36 expression.PART 1: Changes of CD36 and PPARγ Expression in Atherosclerotic Mini SwineOBJECTIVE: To establish an animal model of atherosclerosis in mini swine and then to investigate the changes of CD36 and PPARγ expression in atherosclerotic mini swine.METHODS: Chinese mini swine were fed a normal diet or a high fat/high cholesterol diet (HFHC) for 12 months. Atherosclerotic lesion of aorticarteries were stained with heraatoxylin eosin. CD36 and PPAR y mRNA and protein levels were determined by reverse transcription-polymerase chain reaction(RT-PCR), Western blotting and immunohistochemistry respectively. RESULTS: At the end of 12 months, High fat/high cholesterol diet induced atherosclerotic plaque in Chinese mini swine. CD36 and PPARy expression was upregulated in atherosclerotic mini swine.CONCLUSION: CD36 and PPAR y expression in atherosclerotic mini swine were upregulated.PART 2 Effect of oxLDL on CD36 Expression in MacrophageOBJECTIVE: To investigate the effect of oxLDL on CD36 expression andcholesterol influx in THP-1 macrophage.METHODS: THP-1 macrophage were treated with 50mg/L oxLDL for Oh, 12h, 24h, 36h,48h respectively. Oil red O staining was used to observe the intracellularlipid droplets. [3H]labeled Cholesterol influx was determined by FJ-2107P typeliquid scintillator. CD36 mRNA and protein level were determined by reversetranscription-polymerase chain reaction(RT-PCR) and Western blottingrespectively.RESULTS: We found that oxLDL elevated CD36 in both protein and mRNA levels andincreased cholesterol influx in a time-dependent manner. The levels ofcholesterol influx were 23. 5%, 27. 8%^ 39. 7%> 44. 1% and 49. 7% respectively.CONCLUSION: oxLDL may upregulate CD36 expression and increase cholesterolinflux.PART 3 Effect of PPARy on CD36 Expression and Cell Cholesterol Influx in THP-1 MacrophageOBJECTIVE: To investigate the effect of PPAR y on CD36 expression andcholesterol influx in THP-1 macrophage.METHODS: After exposure of the cultured THP-1 macrophage to ciglitazone and...