Effects of cigarette smoking on HDL quantity and function: implications for atherosclerosis

Cigarette smoking has been identified as an independent and preventable risk factor for atherosclerosis and cardiovascular disease. Population studies have shown that plasma high density lipoprotein (HDL) cholesterol levels are inversely related to the risk of developing cardiovascular disease. Cigarette smoking is associated with reduced HDL cholesterol levels. Cigarette smoking can alter the critical enzymes of lipid transport, lowering lecithin: cholesterol acyltransferase (LCAT) activity and altering cholesterol ester transfer protein (CETP) and hepatic lipase activity, which attributes to its impact on HDL metabolism and HDL subfractions distribution. In addition, HDL is susceptible to oxidative modifications by cigarette smoking, which makes HDL become dysfunctional and lose its atheroprotective properties in smokers. Therefore, cigarette smoking has a negative impact on both HDL quantity and function, which can explain, in part, the increased risk of cardiovascular disease in smokers.

PEGylated helper-dependent adenoviral vector expressing human Apo A-I for gene therapy in LDLR-deficient mice

Helper-dependent adenoviral (HD-Ad) vectors have great potential for gene therapy applications; however, their administration induces acute toxicity that impairs safe clinical applications. We previously observed that PEGylation of HD-Ad vectors strongly reduces the acute response in murine and primate models. To evaluate whether PEGylated HD-Ad vectors combine reduced toxicity with the correction of pathological phenotypes, we administered an HD-Ad vector expressing the human apolipoprotein A-I (hApoA-I) to low-density lipoprotein (LDL)-receptor-deficient mice (a model for familial hypercholesterolemia) fed a high-cholesterol diet. Mice were treated with high doses of HD-Ad-expressing apo A-I or its PEGylated version. Twelve weeks later, LDL levels were lower and high-density lipoprotein (HDL) levels higher in mice treated with either of the vectors than in untreated mice. After terminal killing, the areas of atherosclerotic plaques were much smaller in the vector-treated mice than in the control animals. Moreover, the increase in pro-inflammatory cytokines was lower and consequently the toxicity profile better in mice treated with PEGylated vector than in mice treated with the unmodified vector. This finding indicates that the reduction in toxicity resulting from PEGylation of HD-Ad vectors does not impair the correction of pathological phenotypes. It also supports the clinical potential of these vectors for the correction of genetic diseases.