Serum apolipoprotein j in health, coronary heart disease and type 2 diabetes mellitus.

Apolipoprotein (apo) J, clusterin, is ubiquitously expressed in many tissues, and is a component of high-density lipoproteins (HDLs). There is experimental evidence that it may be anti-atherogenic through its effects on cholesterol transport, smooth muscle cell proliferation and lipid peroxidation. HDLs containing apo J and apo A-I carry paraoxonase (PON1), which protects low-density lipoproteins from oxidative modification; however, the extent to which apo J affects coronary heart disease (CHD) is not known. We have developed a sandwich ELISA that enables apo J to be assayed in the range of 13-200 microg/mL. Serum apo J was 52.8+/-0.8 microg/mL (mean+/-SEM; range, 36.0-84.3 microg/mL; n=92) in healthy Japanese men, and 49.3+/-0.5 microg/mL (34.5-72.8; n=241) in healthy Japanese women. Multiple regression of these data and results from 67 men with CHD showed that apo J concentration was unrelated to age, sex or body mass index, but was positively related to serum PON1 (p<0.001) and apo B (p<0.02) concentrations. In women, it was also positively related to blood glucose (p<0.02). After adjusting for its associations with covariates, serum apo J averaged 5.4 microg/mL, lower in CHD men than in controls (p<0.003). Type 2 diabetics had higher apo J concentrations (men, 83.1+/-3.4 microg/mL, n=64; women, 64.0+/-2.3 microg/mL, n=46) than healthy men and women (p<0.001). In these Type 2 diabetics, apo J concentration was unrelated to PON1 concentration, but was positively related to blood glucose (p<0.01). After adjustment for its relation to blood glucose, the mean apo J concentration was similar in diabetics and healthy subjects. These findings suggest that apo J may be anti-atherogenic in humans, and that its concentration is raised by Type 2 diabetes.

[Atherosclerotic regression in the aortas of elderly. (4). Expression of peroxisome proliferator-activated receptors with references of centrally depressed atherosclerotic plaque].

Peroxisome proliferator-activated receptors (PPARs) play an important role in vascular events during progression of atherosclerosis, associated with lipid metabolism, inflammatory response and others. To clarify relationships between the expression of PPARs subtypes and regression, we studied mRNA expression of PPARs subtypes with reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry, especially in centrally depressed atherosclerotic plaques (depressed plaque) in the aortas of elderly patients, and proposed morphological feature of atherosclerotic regression. Samples were separated from the depressed plaque, atheromatous plaque, and diffuse intimal thickening (DIT) in the aortas of elderly patients at autopsy and they were analyzed for RT-PCR. The depressed plaques obtained were divided into two parts: depressed area and surrounding elevated area. Total RNA was prepared, using the TRIzol Reagent, and was reverse transcribed using random hexamer primers and Thermoscript kit for RT-PCR. Immunohistochemical analysis was processed for mouse anti-PPAR gamma antibody, detected by the ABC method. 1) Decreased foam cells were found in the depressed area than in the surrounding elevated area of the depressed plaque. These foam cells were immunohistochemically positive for HAM56 and strong reactivities for PPAR gamma were found in the nuclei of macrophage-derived foam cells. PPAR gamma was also detected in the nuclei of endothelial cells and smooth muscle cells. 2) Expressions of PPAR alpha and PPAR gamma were found in the depressed plaques with RT-PCR. These expressions were found both in the depressed area and the surrounding elevated area without significant differences. 3) PPAR gamma mRNA expression both in the depressed area and the surrounding elevated area, was greater than in DIT, and was less than in the atheromatous plaque. 4) Expression of PPAR gamma mRNA was intense and increased in the surrounding elevated area than in the depressed area. 5) A significant increase of PPAR gamma expression was found in the atheromatous plaque than in the DIT. 6) There was no significant difference of PPAR alpha mRNA expression between the depressed area and the surrounding elevated area. The depressed plaque has been considered to be a morphological characteristic of regression in recent studies. Expression of mRNA for PPARs was detected in the depressed plaque as well as the atheromatous plaque, furthermore, there were different expressions and intensity of PPARs between the depressed area and the surrounding elevated area of the depressed plaque. These findings suggest that the expression of PPARs may be involved not only in the progression of atherosclerosis but also in regression.

Chylomicron accelerates C3 tick-over by regulating the role of factor H, leading to overproduction of acylation stimulating protein.

Acylation stimulating protein (ASP) is a fragment of the third component of complement (C3) that is generated in the presence of chylomicron, and plays a role in the synthesis of triacylglycerol by transporting free fatty acids into adipocytes. However, the precise mechanism of ASP generation, especially the role of chylomicron in ASP generation, is unknown. We examined the mechanism through which chylomicron induces ASP generation. Ultracentrifugationally separated chylomicron was incubated with normal human serum (NHS) under various conditions, and the amounts of complement activation products and ASP in the incubation mixture were determined by enzyme-linked immunosorbent assay (ELISA). Upon incubation of NHS with various amounts of chylomicron for 120 min, ASP was generated in a dose-dependent manner. The time course of the production of ASP was similar to the time course of the C3 tick-over phenomenon that occurred by depletion of factor H from the serum. The complement activation induced by chylomicron was different from the usual complement activation that occurs under the regulation of factor H and factor I with respect to the time course and the amount of ASP produced. Our results indicate that chylomicron accelerates C3 tick-over by regulating the role of factor H, leading to the overproduction of ASP.

Association of coronary heart disease with pre-beta-HDL concentrations in Japanese men.

BACKGROUND: In individuals heterozygous for ABCA1 transporter mutations, defective reverse cholesterol transport (RCT) causes low HDL-cholesterol and premature coronary heart disease (CHD). However, the extent to which impaired RCT underlies premature CHD in others with low HDL-cholesterol is not known. The primary acceptors of cell cholesterol are a minor subclass of lipid-poor pre-beta-HDLs. These are generated during remodeling of alpha-HDLs, which account for almost all HDL-cholesterol. We studied the strength of the association of CHD with pre-beta-HDL concentrations in Japanese men. METHODS: Blood was collected from 42 men with clinical CHD and 44 healthy controls 40-70 years of age. Pre-beta-HDL was assayed by crossed immunoelectrophoresis. RESULTS: Cases had lower HDL-cholesterol (-23%), total apolipoprotein A-I (-26%), and pre-beta-HDL (-55%; all P <0.001) concentrations; lower pre-beta-HDL:alpha-HDL ratios (-45%; P <0.001); and higher plasma triglycerides (20%; P <0.03) than the controls. On stepwise logistic regression, CHD was associated most strongly with pre-beta-HDL concentrations. On ROC analysis, pre-beta-HDL concentration discriminated between cases and controls better than any other lipoprotein measurement. When plasma was incubated for 16 h at 37 degrees C, mean (SD) pre-beta-HDL increased by 47 (36)% in controls, but was unchanged in cases (group difference, P <0.001). CONCLUSIONS: Our results suggest that inefficient RCT, secondary to a low pre-beta-HDL concentration and production rate in plasma, contributes to premature CHD in Japanese men with low HDL-cholesterol.