Tracheal epithelial cell fatty acid composition modulates prostaglandin E2 and cAMP production

Abstract

Tracheal epithelial (TE) cells from both rabbits and humans, when cultured in defined serum-free media without lipid supplements, develop fatty acid profiles significantly different from freshly isolated epithelium, including a markedly decreased cellular content of arachidonic acid (AA). In rabbit TE cells, supplementation of media with a phospholipid-rich lipoprotein extract (Excyte III) plus 1 microM bovine serum albumin-complexed AA (Excyte/AA) restored the fatty acid composition of the cultured cells more similar to that of native airway epithelium than did supplementation of media with 5% fetal bovine serum (FBS). In human TE cells, Excyte/AA or 5% FBS increased AA content, but neither lipid supplement completely "normalized" the fatty acid profiles. Compared with lipid-unsupplemented cultures, basal production of prostaglandin E2 (PGE2) was increased by approximately four- to eightfold in rabbit and human TE cells supplemented with 5% FBS or Excyte/AA. In Excyte/AA-supplemented human TE cells, PGE2 production induced by 5 microM calcium ionophore A23187 was more than threefold greater than that of companion ionophore-stimulated unsupplemented monolayers, but PGE2 production was similar in both culture conditions in response to 10 microM exogenous AA. Thus increased cellular content and availability of AA, rather than changes in cyclooxygenase activity, appear to be responsible for the elevated PGE2 production in Excyte/AA-supplemented human TE cells. Secondary effects of lipid supplementation were also observed; Excyte/AA-supplemented human TE cells produced significantly less adenosine 3',5'-cyclic monophosphate (cAMP) in response to exogenous PGE2 and isoproterenol than did lipid-unsupplemented cells.(ABSTRACT TRUNCATED AT 250 WORDS)