Blockade of scavenger receptor class B type I raises high density lipoprotein cholesterol levels but exacerbates atherosclerotic lesion formation in apolipoprotein E deficient mice.

Abstract

Recent accumulating evidence supports the concept that raising high-density lipoprotein (HDL) may represent an additional therapeutic target for prevention of cardiovascular disease. Scavenger receptor class B type I plays a critical role in plasma HDL cholesterol concentration and structure. This study investigated the effect of scavenger receptor class B type I blockade by a synthetic scavenger receptor class B type I blocker on plasma lipids and atherosclerosis lesion formation in apolipoprotein E (apoE)-deficient mice. N-[4-(4-tert-Butoxycarbonylpiperazin-1-yl)phenyl]-(2-chloro-5-nitrophenyl)carboxamide (R-138329), a novel scavenger receptor class B type I blocker, was identified by screening with a half-maximal inhibitory potency (IC50 value) of around 1 microM in scavenger receptor class B type I-expressing COS-1 cells. Male apoE-deficient mice were fed a chow diet with or without R-138329 (0.01-0.10%, approximately 10-100 mg kg(-1), n = 9 or 10) for 12 weeks. Compared with control, treatment with R-138329 at 0.10% caused significant (P < 0.05) increases in plasma HDL cholesterol levels, and decreases in non-HDL cholesterol and triglyceride levels. Furthermore, R-138329 at 0.01% significantly increased the extent of atherosclerotic lesion formation in the aorta by 98% (P < 0.05), while favourable changes in plasma lipid parameters were achieved. The results of quantitative analysis of atherosclerosis lesion areas were: control, 102691 +/-22871 microm(2) (n = 10); R-138329 0.01%, 119792+/-30842 microm(2) (n = 9); R-138329 0.03%, 141346+/-21934 microm(2) (n = 10); and R-138329 0.10% 203732+/- 36326 microm(2) (n = 10). To clarify the mechanistic basis underlying this preferential deterioration, we examined the potential impact on closely related cellular functions. Further studies revealed that the active metabolite of R-138329 inhibited scavenger receptor class B type I-mediated cholesterol efflux. This study demonstrates for the first time pharmacological blockade of scavenger receptor class B type I in apoE-deficient mice. Blockade of scavenger receptor class B type I deteriorates atherosclerotic lesion formation in apoE-deficient mice even though it favourably affects plasma lipid parameters such as raising HDL cholesterol and decreasing non-HDL cholesterol. These results provide new insights for pharmaceutical industry research and development issues.

• Authors: Ken Kitayama, Tomohiro Nishizawa, Koji Abe, Kenji Wakabayashi, Tomiichiro Oda, Toshimori Inaba, Yoshiya Amemiya
• Journal: The Journal of pharmacy and pharmacology (J Pharm Pharmacol) Vol. 58 Issue 12 Pg. 1629-38 (Dec 2006) ISSN: 0022-3573 [Print] England
• PMID: 17331327 (Publication Type: Journal Article)

Chemical References

• Apolipoproteins E
• Cholesterol, HDL
• N-(4-(4-tert-butoxycarbonylpiperazin-1-yl)phenyl)-(2-chloro-5-nitrophenyl)carboxamide
• Piperazines
• R-154716
• SCARB1 protein, human
• Scavenger Receptors, Class B

Topics

• Animals
• Apolipoproteins E (deficiency, genetics)
• Atherosclerosis (metabolism, pathology, prevention & control)
• COS Cells
• Cell Line
• Chlorocebus aethiops
• Cholesterol, HDL (blood, metabolism)
• Disease Models, Animal
• Dose-Response Relationship, Drug
• Humans
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Molecular Structure
• Piperazines (chemistry, pharmacology, therapeutic use)
• Scavenger Receptors, Class B (antagonists & inhibitors)
• Transfection