Incorporation of phytosterols in human keratinocytes. Consequences on UVA-induced lipid peroxidation and calcium ionophore-induced prostaglandin release.
We have designed experimental conditions allowing the replacement of 50% of cholesterol of human keratinocytes (SVK14 line) with sitosterol or stigmasterol without affecting cellular viability. We have investigated the influence of incorporating phytosterol on the ultraviolet-A-induced formation of lipid-peroxidation products (thiobarbituric reactive substances (TBARS)) in these cells. Our results show that ultraviolet-A-induced lipid peroxidation depends on the nature of the phytosterol. Sitosterol induces a significant decrease (-30%) of TBARS relative to the control whereas stigmasterol markedly increases lipid peroxidation (+70%). We have also studied the effect of plant sterols on prostaglandin release by using the Ca(2+) ionophore A23187 as an in vitro model of the inflammation induced by UVA radiation. We show that in the presence of 50% of phytosterol (particularly stigmasterol), the release of prostaglandin (6-ketoPG(1alpha), PGE(2)) is increased compared to untreated cells. This pro-inflammatory effect of phytosterols is correlated with a loss of the regulation of the intracellular Ca(2+) concentration.
Mora-Ranjeva
M P
MP
Institut de Pharmacologie et de Biologie Structurale, CNRS, Toulouse, France.
Charveron
M
M
Fabre
B
B
Milon
A
A
Muller
I
I
D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology; D006801:Humans; D015603:Keratinocytes / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000528:radiation effects; D010840:Phytosterols / Q000494:pharmacology*; D011453:Prostaglandins / Q000378:metabolism*; D012855:Sitosterols / Q000494:pharmacology; D013265:Stigmasterol / Q000494:pharmacology; D014466:Ultraviolet Rays
D002413:Cations, Divalent; D010840:Phytosterols; D011453:Prostaglandins; D012855:Sitosterols; C025473:gamma-sitosterol; D002784:Cholesterol; D013265:Stigmasterol; D002118:Calcium