Chylomicron metabolism is markedly altered in systemic lupus erythematosus

Objective. To verify the in vivo status of chylomicron metabolism in system ic lupus erythematosus (SLE) since there is a high incidence of atheroscler osis in this disease and chylomicrons may have an important role in atherog enesis. Methods, A chylomicron-like emulsion labeled with C-14-cholesteryl esters a nd H-3-triglycerides was injected intravenously into 10 female patients wit h inactive SLE and 10 healthy age- and sex-matched control subjects to dete rmine the plasma kinetics of the emulsion lipids from consecutive plasma sa mples taken at regular intervals for 1 hour. Lipolytic activity was determi ned in vitro after incubation of the labeled emulsion with postheparin plas ma. Results. The decay curves for the emulsion were markedly slowed in SLE. Chy lomicron lipolysis, indicated by the fractional clearance rate (FCR) of emu lsion H-3-triglyceride, was 2-fold smaller in SLE patients than in controls (mean +/- SD 0.023 +/- 0.011 versus 0.047 +/- 0.015 minute(-1); P = 0.010) . Chylomicron removal, indicated by emulsion C-14-cholesteryl ester FCR, wa s 3-fold smaller in SLE patients than in controls (0.007 +/- 0.007 versus 0 .023 +/- 0.011 minute(-1); P = 0.009). In vitro lipolysis in SLE patients w as nearly half that of the controls (mean +/- SD 10,199 +/- 2,959 versus 6, 598 +/- 2,215; P = 0.014). Higher levels of very-low-density lipoprotein ch olesterol and triglycerides and lower levels of high-density lipoprotein ch olesterol and apolipoprotein A-I were also observed in the SLE patients. Conclusion. SLE patients have disturbances in chylomicron metabolism that a re characterized by decreased lipolysis and chylomicron remnant removal fro m the plasma. This finding, together with other alterations in lipid profil es that were confirmed in the present study, is largely accountable for the accelerated atherosclerotic process of the disease.