25-hydroxycholesterol increases eicosanoids and alters morphology in cultured pulmonary artery smooth muscle and endothelial cells

25-Hydroxycholesterol (25-OHC) is an oxidized derivative of cholesterol tha t has been implicated in the early development of arteriosclerosis. Changes in arterial smooth muscle cell (SMC) migration and proliferation have also been linked to the pathophysiology of arteriosclerosis. SMCs undergo "acti vation" in response to vascular injury by changing phenotypically and by in creasing prostaglandin G/H synthase-2 (PGHS-2) protein levels and eicosanoi d release. Activation is thought to be important in atheroma formation and arteriosclerosis progression. 25-OHC induces SMCs to change morphologically , increase PGHS-2, and increase eicosanoid release. Confluent monolayers we re treated with 25-OHC (10 mu g/mL) or the PGHS-2 inducer interleukin-1 bet a (1 ng/mL) for 18 hours at 37 degrees C. The 18-hour treatment resulted in morphological changes. After uptake of [C-14]arachidonic acid, released ra diolabeled arachidonic acid products were extracted and chromatographed by both normal and reverse-phase high-performance liquid chromatography system s. 25-OHC-treated cells increased their prostaglandin production, with the major component comigrating with a prostaglandin-E-2 standard. HETEs and ep oxyeicosatrienoic acids were not affected. Immunoprecipitation analysis of treated and control cell lysates using anti-PGHS-1 and -2 and anti-alpha-ac tin primary antibodies indicated PGHS-2 induction over control and no chang e in contractile proteins. These changes are consistent with SMC activation . which occurs in vascular injury models. The notion that oxysterols can ac tivate vascular SMCs may be important in ultimately understanding the patho physiology of atheroma formation.