Alteration in rat apolipoprotein C-III gene expression and lipoprotein composition during inflammation.

A cloned rat apolipoprotein (apo) C-III cDNA was used as a hybridization probe to measure apo C-III mRNA levels in rats after induction of inflammation. Hepatic apo C-III mRNA levels decrease to a minimum value of 46% of normal 72 h after the induction of inflammation. The changes observed are very similar to the changes in mRNA levels of rat apo A-IV, while the hepatic mRNA levels for apo A-I and apo C-I during inflammation remain relatively constant. Alterations in apo C-III gene expression during inflammation were associated with changes in lipoprotein particle size and composition. A decrease of approximately twofold in the amount of apo C-III-containing HDL particles was found in rats 24 h after the induction of inflammation. The average size of apo C-III-containing HDL particles in rats during inflammation is significantly larger than that of the control group. A decrease in the concentration of apo A-I-containing HDL particles was also observed in these rats. The results indicate altered apolipoprotein gene expression associated with alterations in the size and composition of HDL particles.