Study of cultured skin fibroblasts from patients with and without ischemic heart disease. Metabolism of low density lipoprotein and cholesterol ester, synthesis of cellular lipids and effect of chloroquine on accumulation of cholesterol ester.

The aim of the present study was to determine whether skin fibroblasts derived from patients with ischemic heart disease (IHD), which could not be related to accepted risk factors, would show a metabolic abnormality with respect to lipid or lipoprotein metabolism. Male patients 30-52 years old suffering from IHD were subdivided into two groups: those in whom IHD was not associated with risk factors such as hypertension, hyperlipoproteinemia, diabetes or smoking (group I); and those in whom heavy smoking was the only major risk factor recognized (group II). The controls were patients with angiographically normal coronary arteries (group III). Skin fibroblasts obtained from these patients were cultured and investigated with respect to metabolism of low density lipoprotein (LDL), synthesis of cellular lipids and induction of cholesterol ester accumulation in the presence of chloroquine, an inhibitor of lysosomal hydrolases. After 24 h incubation, the uptake and degradation of LDL protein in cells from patients of group II was significantly higher than in the controls, group III, but not different from those of group I. Hydrolysis of [3H] cholesterol linoleate, and incorporation of [3H] oleic acid into total lipids and into cholesterol esters was similar in cell cultures of the 3 groups studied. After exposure to chloroquine and LDL, the cells from the different donors accumulated cholesterol ester to a similar extent. Thus, whereas no significant difference was encountered in the lipid and lipoprotein metabolism in cells of patients with IHD without risk factors and controls, some increase in LDL metabolism was seen in cells from patients with IHD and with a history of smoking. It remains to be determined whether this increase was causally related to smoking.