A novel compound that elevates high density lipoprotein and activates the peroxisome proliferator activated receptor

In the current studies we describe the effects of PD 72953 and related compounds on lipoprotein levels in chow-fed male rats. After 2 weeks, 10 mg/kg of PD 72953 daily was as effective as 100 mg/kg gemfibrozil for elevating HDL-cholesterol. At 100 mg/kg, PD 72953 further elevated HDL-cholesterol to 232% of control levels, and was associated with increased HDL size and plasma apoE (169% of control), despite no change in hepatic apoE mRNA. ApoA-I rose transiently (at 1 week), but by 2 weeks only apoE remained elevated. PD 72953 dose-dependently reduced plasma apoB, VLDL-cholesterol, LDL-cholesterol, and triglyceride. Hepatic apoC-III mRNA reduction parallelled triglyceride lowering. After 1 week, 30 and 100 mg/kg per day PD 72953 reduced plasma apo-CIII levels by 30 and 34%, and triglycerides by 60 and 83%, respectively. PD 72953 treatment had no effect on triglyceride production rates; however, 125I-labeled VLDL apoB disappearance was enhanced. We compared PD 72953 to a structurally similar diacid, PD 69405, that also reduced VLDL and LDL, but had no effect on HDL elevation. Compared to PD 72953, PD 69405 further accelerated 125I-labeled VLDL apoB disappearance, decreased triglyceride production, and elevated the ratio of post-heparin hepatic to lipoprotein lipase activity. Whole animal studies, transient transfection studies in HepG2 cells, and chimeric receptor studies in kidney 293 cells suggest that PD 72953 is a ligand for the peroxisomal proliferation activated receptor alpha (PPARalpha), and PPARgamma. Overall, PD 72953 may act through a peroxisomal proliferation activated receptor and result in plasma triglycerides and apoB-containing lipoprotein reduction, while also raising HDL cholesterol. Reduced apoC-III may allow triglyceride-rich remnants to more efficiently bind and present substrate to peripheral tissue lipoprotein lipase, and therefore allow enhanced shedding of remnant phospholipid surface for HDL production.