Low density lipoprotein receptors in cultured skin fibroblasts from psoriasis patients

Low density lipoprotein (LDL) receptor activity, measured as 125I-LDL association and degradation at 37 degrees C, was determined in cultured fibroblasts from involved as well as uninvolved skin obtained from 20 psoriasis patients. The same analyses were conducted in fibroblasts from two reference groups consisting of 19 heterozygotes for familial hypercholesterolemia and 16 normal subjects, respectively. Psoriasis patients had significantly lower LDL receptor activity than normals, and it was comparable to that of the heterozygotes for familial hypercholesterolemia. The reduced LDL receptor activity was not accompanied by an increase in total serum cholesterol. The psoriasis patients had a significant reduction in apo-B concentration, but did not differ from the normals in the other serum lipid or lipoprotein parameters. There was no difference in LDL receptor activity between involved and uninvolved skin from psoriasis patients. These results suggest that there is an abnormal cell membrane in dermal fibroblasts from psoriasis patients. Since their total serum cholesterol is normal, their low LDL receptor activity may be confined to dermal cells, leaving the hepatic lipid metabolism normal. The pathogenetic significance of this finding is unknown.