Liver-specific Lxr inhibition represses reverse cholesterol transport in cholesterol-fed mice.

BACKGROUND AND AIMS: High density lipoprotein (HDL) exerts an anti-atherosclerotic effect via reverse cholesterol transport (RCT). Several phases of RCT are transcriptionally controlled by Liver X receptors (Lxrs). Although macrophage Lxrs reportedly promote RCT, it is still uncertain whether hepatic Lxrs affect RCT in vivo. METHODS: To inhibit Lxr-dependent pathways in mouse livers, we performed hepatic overexpression of sulfotransferase family cytosolic 2B member 1 (Sult2b1) using adenoviral vector (Ad-Sult2b1). Ad-Sult2b1 or the control virus was intravenously injected into wild type mice and Lxrα/ß double knockout mice, under a normal or high-cholesterol diet. A macrophage RCT assay and an HDL kinetic study were performed. RESULTS: Hepatic Sult2b1 overexpression resulted in reduced expression of Lxr-target genes - ATP-binding cassette transporter G5/G8, cholesterol 7α hydroxylase and Lxrα itself - respectively reducing or increasing cholesterol levels in HDL and apolipoprotein B-containing lipoproteins (apoB-L). A macrophage RCT assay revealed that Sult2b1 overexpression inhibited fecal excretion of macrophage-derived 3H-cholesterol only under a high-cholesterol diet. In an HDL kinetic study, Ad-Sult2b1 promoted catabolism/hepatic uptake of HDL-derived cholesterol, thereby reducing fecal excretion. Finally, in Lxrα/ß double knockout mice, hepatic Sult2b1 overexpression increased apoB-L levels, but there were no differences in HDL levels or RCT compared to the control, indicating that Sult2b1-mediated effects on HDL/RCT and apoB-L were distinct: the former was Lxr-dependent, but not the latter. CONCLUSIONS: Hepatic Lxr inhibition negatively regulates circulating HDL levels and RCT by reducing Lxr-target gene expression.

Effects of Dietary Education Program for the Japan Diet on Cholesterol Efflux Capacity: A Randomized Controlled Trial.

AIM: Improving cholesterol efflux capacity (CEC) of high-density lipoprotein (HDL) has been regarded as a novel target for preventing cardiovascular disease. HDL reportedly has antioxidant properties which may contribute to its functions. We investigated changes in CEC with intake of the Japan Diet (JD) recommended by the Japan Atherosclerosis Society and the relationship of these changes to serum antioxidant concentrations. METHODS: A randomized parallel controlled clinical trial on JD intake was performed in Japanese patients with dyslipidemia. Ninety-eight participants were randomly divided into the JD (n=49) or the partial JD (PJD) (n=49) group. Nutrition education, based on each diet at baseline and at 3 months, was provided and the participants were followed up for 6 months. RESULTS: Mean CEC was 1.05 in total and correlated positively with HDL-cholesterol (p＜0.001) at baseline. CEC did not change while oxygen radical absorbance capacity (ORAC) was decreased in both groups (p＜0.001). Although serum total carotenoid increased in both groups, serum α-tocopherol decreased in the JD group as compared to the PJD group (p＜0.05). CEC correlated positively with HDL ORAC at baseline (p=0.021) and with serum total carotenoid at 3 and 6 months (p=0.005, 0.035). Changes in CEC correlated positively with changes in HDL ORAC at 3 months and serum total tocopherol at 3 and 6 months (p＜0.001). CONCLUSION: CEC was not changed by JD education in Japanese patients with dyslipidemia who already had normal CEC at baseline. CEC was suggested to be positively associated with serum α- and γ-tocopherol and HDL ORAC.

Inhibitory assay for degradation of collagen IV by cathepsin B with a surface plasmon resonance sensor.

We describe a simple method for evaluating the inhibition of collagen IV degradation by cathepsin B with a surface plasmon resonance (SPR) biosensor. The change in the SPR signal decreased with an increase in the concentration of cathepsin B inhibitors. The order of the inhibitory constant (Ki) obtained by the SPR method was CA074Me≈Z-Phe-Phe-FMK < leupeptin. This order was different from that obtained by benzyloxycarbonyl-Phe-Phe-Fluoromethylketone (Z-Phe-Phe-FMK) as a peptide substrate. The comparison of Ki suggested that CA074 and Z-Phe-Phe-FMK inhibited exopeptidase activity, and leupeptin inhibited the endopeptidase activity of cathepsin B more strongly.