NO-1886 Regulates Reverse Cholesterol Transport-related Genes, Suppressing Atherosclerosis

Background and the aim LPL is a key enzyme that hydrolyzes circulating TRL such as very low density lipoprotein (VLDL) and chylomicrons (CM). The novel compound NO-1886 developed by Otsuka Pharmaceutical Factory Inc. Tokushima, Japan, is a LPL activator that has been proven to be highly effective in improving the chronic metabolic disorder of lipid. NO-1886 accelerates the expression of LPL mRNA in adipose tissue, cardiac muscle and skeletal muscle, increases the LPL protein mass and LPL activity in plasma, thereby reducing plasma TG level and elevating plasma high density lipoprotein cholesterol (HDL-C) level.Results from numerous epidemiological studies have documented a reciprocal relationship between atherosclerotic coronary heart disease and high-density lipoprotein (HDL) levels. A long-standing hypothesis to explain this protective effect of HDL-C against atherosclerosis is the process of reverse cholesterol transport (RCT). In RCT, HDL or its apolipoproteins mediate the removal of excess free cholesterol (FC) from peripheral cells and, after a series of reactions in plasma, the cholesterol is delivered via either LDL or HDL to the liver for excretion into the bile. Recent studies have shown that ATP-binding cassette transporter A1 (ABCA1) is of great importance in regulating the efflux of cholesterol from cells. It is involved not only in removing cholesterol from peripheral tissues but also in influencing the production of HDL by the liver and the rate of cholesterol absorption by the gut. The ABCA1 gene is a target for the nuclear hormone transcription factor, liver X receptor (LXR). LXR is believed to act as a sterol sensor in cells upregulating genes involved in cholesterol elimination when cells are faced with excess sterols. The LXR forms obligate heterodimers with retinoid X receptors (RXR), which then enhance the transcriptionof ABCA1 via the same direct repeat 4 (DR4) promoter element. High-density lipoprotein cholesteryl esters (HDL-CE) are selectively taken up by liver parenchymal cells and this selective uptake route forms an important step in reverse cholesterol transport. The scavenger receptor B (SR-B I ) can mediate selective uptake of HDL-CE. Therefore, ABCA1, LXRa and SR-B I are major players in the process of RCT.The aim of this study was to establish a animal model of the human atherosclerosis for investigating the effects of NO-1886 on chronic glucose and lipid metabolism disorder and expression of ABCA1, LXRa in liver, adipose, aorta and of SR-B1 in liver in Guangxi Bama minipigs.Materials and methods Twenty five Bama minipigs were randomized into three groups with similar body weight: control group (CD), high-fat/ high-sucrose/ high-cholesterol group (HFSCD), high-fat/ high-sucrose/ high-cholesterol plus NO-1886 treated group (HFSCD+NO-1886). The animals were fed high-fat/ high-sucrose/ high-cholesterol diet for five months (except the normal control group). NO-1886 treated group were supplemented with 1.0% NO-1886 into the diet. Blood samples were withdrawn from the orbital sinus of the animals at the end of each month after fasting overnight. Blood glucose, FFA, total cholesterol (TC), HDL-C, triglycerides, TC / HDL-C ratio and apoA I were determined. The aortic fatty streak-lesions were quantified following lipid staining with Sudan IV. The levels of ABCA1, LXRa in liver, adipose, aorta and SR-B I in liver were measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.Results NO-1886 decreased atherosclerosis lesions, plasma TG, Glucose, FFA concentration, and TC / HDL-C ratio and increased plasma HDL-C and apoA I concentration. NO-1886 also increased the level of ABCA1 mRNA, ABCA1 protein, LXR a mRNA, LXR a protein in liver, adipose and aorta, and SR-B I mRNA, SR-B I protein in liver.