Decrease of hepatic triglyceride lipase levels and increase of cholesteryl ester transfer protein levels in patients with primary biliary cirrhosis: Relationship to abnormalities in high-density lipoprotein

Abstract

Serum levels of high-density lipoprotein cholesterol are often increased in patients with primary biliary cirrhosis. To elucidate the mechanism of the elevation of high-density lipoprotein cholesterol levels in this disease, lipoprotein abnormalities were analyzed in 10 patients subdivided into two groups according to concentration of high-density lipoprotein cholesterol. Activities and protein masses of lipoprotein lipase, hepatic triglyceride lipase and cholesteryl ester transfer protein were also determined. Serum high-density lipoprotein cholesterol concentration exceeded 90 mg/dl in 5 of 10 patients. Lipoprotein particles in the high-density lipoprotein2 fraction (with density between 1.063 and 1.125 gm/ml) were enriched with apolipoprotein E and larger in size than those of normal controls. In patients with and without hyperalphalipoproteinemia, hepatic triglyceride lipase activity was significantly decreased (p < 0.05); this was due to the reduction of its protein mass. Lipoprotein lipase activity and protein mass were normal. It is noteworthy that increases in cholesteryl ester transfer protein activity and mass were observed. The enhancement of cholesteryl ester transfer protein activity was more remarkable in the patients with hyperalphalipoproteinemia than in those without hyperalphalipoproteinemia. Because a significant positive correlation was demonstrated between activity and protein mass (r = 0.90, p < 0.001), the increase of cholesteryl ester transfer protein activity may be attributed to the increase of its protein mass. These data suggest that the decrease of hepatic triglyceride lipase levels at least partly explains the appearance of apolipoprotein E-rich large high-density lipoprotein particles in patients with primary biliary cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Previous studies [2,3,5,6,14] had established a connection between liver damage due to viral infection and a decline in cholesterol and apolipoprotein metabolism. This relationship was further demonstrated by recent basic and clinical research aimed at uncovering the mechanisms behind these alterations [7,10,13,15].…”

“…In our study, however, TG levels were similar in all three groups. This is probably due to the fact that in late stages of hepatic disease, the activity of TG lipase (the enzyme responsible for hydrolyzing ester linkages of TGs) is severely impaired [6]. …”

“…Infection with hepatitis C (HCV) or B (HBV) viruses leads to hepatic damage, which in turn relates to changes in alterations of the lipid metabolism [6,7,8,9,10]. Different mechanisms are involved, dependent on the stage of the liver disease and the metabolic state [11,12,13].…”

Lipids changes in liver cancer

“…In fact cytokines inhibited lipolysis (Gifford and Lohmann-Matthes, 1987). Hepatic cells are damaged simultaneously in hepatocarcinogenesis, and in patients with this pattern, hepatic TG lipase activity significantly decreases (Hiraoka et al, 1993). The X protein of hepatitis B virus (HBx) plays a major role in hepatocellular carcinoma.…”

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