A first-in-man, randomized, placebo-controlled study to evaluate the safety and feasibility of autologous delipidated high-density lipoprotein plasma infusions in patients with acute coronary syndrome.

OBJECTIVES: This study aimed to determine whether serial autologous infusions of selective high-density lipoprotein (HDL) delipidated plasma are feasible and well tolerated in patients with acute coronary syndrome (ACS). BACKGROUND: Low HDL is associated with increased risk of cardiovascular disease. Plasma selective delipidation converts alphaHDL to prebeta-like HDL, the most effective form of HDL for lipid removal from arterial plaques. METHODS: ACS patients undergoing cardiac catheterization with >or=1 nonobstructive native coronary artery atheroma were randomized to either 7 weekly HDL selective delipidated or control plasma apheresis/reinfusions. Patients underwent intravascular ultrasound (IVUS) evaluation of the target vessel during the catheterization for ACS and up to 14 days following the final apheresis/reinfusion session. 2-D gel electrophoresis of delipidated plasmas established successful conversion of alphaHDL to prebeta-like HDL. The trial was complete with 28 patients randomized. RESULTS: All reinfusion sessions were tolerated well by all patients. The levels of prebeta-like HDL and alphaHDL in the delipidated plasma converted from 5.6% to 79.1% and 92.8% to 20.9%, respectively. The IVUS data demonstrated a numeric trend toward regression in the total atheroma volume of -12.18 +/- 36.75 mm(3) in the delipidated group versus an increase of total atheroma volume of 2.80 +/- 21.25 mm(3) in the control group (p = 0.268). CONCLUSIONS: In ACS patients, serial autologous infusions of selective HDL delipidated plasma are clinically feasible and well tolerated. This therapy may offer a novel adjunct treatment for patients presenting with ACS. Further study will be needed to determine its ability to reduce clinical cardiovascular events.

Complementary roles of farnesoid X receptor, pregnane X receptor, and constitutive androstane receptor in protection against bile acid toxicity.

The nuclear receptors, farnesoid X receptor (FXR) and pregnane X receptor (PXR), are important in maintaining bile acid homeostasis. Deletion of both FXR and PXR in vivo by cross-breeding B6;129-Fxrtm1Gonz (FXR-null) and B6;129-Pxrtm1Glaxo-Wellcome (PXR-null) mice revealed a more severe disruption of bile acid, cholesterol, and lipid homeostasis in B6;129-Fxrtm1Gonz Pxrtm1Glaxo-Wellcome (FXR-PXR double null or FPXR-null) mice fed a 1% cholic acid (CA) diet. Hepatic expression of the constitutive androstane receptor (CAR) and its target genes was induced in FXR- and FPXR-null mice fed the CA diet. To test whether up-regulation of CAR represents a means of protection against bile acid toxicity to compensate for the loss of FXR and PXR, animals were pretreated with CAR activators, phenobarbital or 1,4-bis[2-(3,5-dichlorpyridyloxy)]benzene (TCPOBOP), followed by the CA diet. A role for CAR in protection against bile acid toxicity was confirmed by a marked reduction of serum bile acid and bilirubin concentrations, with an elevation of the expression of the hepatic genes involved in bile acid and/or bilirubin metabolism and excretion (CYP2B, CYP3A, MRP2, MRP3, UGT1A, and glutathione S-transferase alpha), following pretreatment with phenobarbital or TCPOBOP. In summary, the current study demonstrates a critical and combined role of FXR and PXR in maintaining not only bile acid but also cholesterol and lipid homeostasis in vivo. Furthermore, FXR, PXR, and CAR protect against hepatic bile acid toxicity in a complementary manner, suggesting that they serve as redundant but distinct layers of defense to prevent overt hepatic damage by bile acids during cholestasis.