Elevated hepatic apolipoprotein A-I transcription is associated with diet-induced hyperalphalipoproteinemia in rabbits

Effects of Therapeutic Lifestyle Change diets high and low in dietary fish-derived FAs on lipoprotein metabolism in middle-aged and elderly subjects

The effects of Therapeutic Lifestyle Change (TLC) diets, low and high in dietary fish, on apolipoprotein metabolism were examined. Subjects were provided with a Western diet for 6 weeks, followed by 24 weeks of either of two TLC diets (10/group). Apolipoprotein kinetics were determined in the fed state using stable isotope methods and compartmental modeling at the end of each phase. Only the high-fish diet decreased median triglyceride-rich lipoprotein (TRL) apoB-100 concentration (-23%), production rate (PR, -9%), and direct catabolism (-53%), and increased TRL-to-LDL apoB-100 conversion (+39%) as compared with the baseline diet (all P < 0.05). This diet also decreased TRL apoB-48 concentration (-24%), fractional catabolic rate (FCR, -20%), and PR (-50%) as compared with the baseline diet (all P < 0.05). The high-fish and low-fish diets decreased LDL apoB-100 concentration (-9%, -23%), increased LDL apoB-100 FCR (+44%, +48%), and decreased HDL apoA-I concentration (-15%, -14%) and PR (-11%, -12%) as compared with the baseline diet (all P < 0.05). On the high-fish diet, changes in TRL apoB-100 PR were negatively correlated with changes in plasma eicosapentaenoic and docosahexaenoic acids. In conclusion, the high-fish diet decreased TRL apoB-100 and TRL apoB-48 concentrations chiefly by decreasing their PR. Both diets decreased LDL apoB-100 concentration by increasing LDL apoB-100 FCR and decreased HDL apoA-I concentration by decreasing HDL apoA-I PR.

Helper-dependent adenoviral vectors are superior in vitro to first-generation vectors for endothelial cell-targeted gene therapy

Arterial endothelial cells (EC) are attractive targets for gene therapy of atherosclerosis because they are accessible to hematogenous and catheter-based vector delivery and overlie atherosclerotic plaques. Vector-mediated expression-in EC-of proteins that mediate cholesterol transfer out of the artery wall and decrease inflammation could prevent and reverse atherosclerosis. However, clinical application of this strategy is limited by lack of a suitable gene-transfer vector. First-generation adenovirus (FGAd) is useful for EC gene transfer in proof-of-concept studies, but is unsuitable for atheroprotective human gene therapy because of limited duration of expression and proinflammatory effects. Moreover, others have reported detrimental effects of FGAd on critical aspects of EC physiology including proliferation, migration, and apoptosis. Here, we investigated whether helper-dependent adenovirus (HDAd) either alone or expressing an atheroprotective gene [apolipoprotein A-I (apoA-I)] could circumvent these limitations. In contrast to control FGAd, HDAd did not alter any of several critical EC physiologic functions (including proliferation, migration, apoptosis, metabolic activity, and nitric oxide (NO) production) and did not stimulate proinflammatory pathways [including expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and interleukin-6 (IL-6)]. Expression of apoA-I by HDAd reduced EC VCAM-1 expression. HDAd is a promising vector and apoA-I is a promising gene for atheroprotective human gene therapy delivered via EC.

The paradox of high apolipoprotein A-I levels independently predicting incident type-2 diabetes among Turks

BACKGROUND

Predictive value of apolipoprotein (apo) A-I for incident hypertension, metabolic syndrome (MetS), type 2 diabetes (DM) and coronary heart disease (CHD) needs further exploration.

METHODS

A representative sample of Turkish adults was studied with this purpose prospectively. Sex-specific apoA-I tertiles were examined regarding cardiometabolic risk.

RESULTS AND CONCLUSIONS

A total of 1044 men and 1067 women (aged 49+/-12 years at baseline) were followed up over 7.4 years. High serum apoA-I levels were significantly associated in multivariable analysis with female sex, aging, alcohol intake, (inversely) cigarette smoking and, in women, with systolic blood pressure. Risk of diabetes was predicted in logistic regression in both genders by top versus bottom apoA-I tertile (RR 1.98; [95%CI 1.31; 3.0]), additive to age, body mass index (BMI), C-reactive protein (CRP), HDL-cholesterol and lipid lowering drugs. By adding sex hormone-binding globulin to the model in a subset of the sample, the association between high apoA-I and incident diabetes was attenuated only in women. ApoA-I tertiles tended to be positively associated also with hypertension and CHD only in women but this did not reach significance. High compared with low serum apoA-I levels nearly double the risk for incident diabetes, additively to age, BMI, CRP, HDL-cholesterol among Turks. Systemic inflammation concomitant with prevailing MetS might turn apoA-I into proinflammatory particles.

The effect of select nutrients on serum high-density lipoprotein cholesterol and apolipoprotein A-I levels

One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol (HDLc). Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). The low plasma concentrations of HDL could be the result of increased fractional clearance and reduced expression of apo A-I. To this end, nutrients play an important role in modulating the fractional clearance rate, as well as the rate of apo A-I gene expression. Because medical nutrition therapy constitutes the cornerstone of management of dyslipidemias, it is essential to understand the mechanisms underlying the changes in HDL level in response to alterations in dietary intake. In this review, we will discuss the effect of select nutrients on serum HDLc and apo A-I levels. Specifically, we will review the literature on the effect of carbohydrates, fatty acids, and ketones, as well as some of the nutrient-related metabolites, such as glucosamine and the prostanoids, on apo A-I gene expression. Because there are multiple mechanisms involved in the regulation of serum HDLc levels, changes in gene transcription do not necessarily correlate with clinical observations on serum levels of HDLc.

Transcriptional regulatory mechanisms of the human apolipoprotein genes in vitro and in vivo

The present review summarizes recent advances in the transcriptional regulation of the human apolipoprotein genes, focusing mostly, but not exclusively, on in-vivo studies and signaling mechanisms that affect apolipoprotein gene transcription. An attempt is made to explain how interactions of transcription factors that bind to proximal promoters and distal enhancers may bring about gene transcription. The experimental approaches used and the transcriptional regulatory mechanisms that emerge from these studies may also be applicable in other gene systems that are associated with human disease. Understanding extracellular stimuli and the specific mechanisms that underlie apolipoprotein gene transcription may in the long run allow us to selectively switch on antiatherogenic genes, and switch off proatherogenic genes. This may have beneficial effects and may confer protection from atherosclerosis to humans.