Cytokine regulation of adult human osteoblast-like cell prostaglandin biosynthesis.
Prostaglandin (PG) biosynthesis by cytokine stimulated normal adult human osteoblast-like (hOB) cells was evaluated by thin layer chromatography, high performance liquid chromatography, and specific immunoassays. PGE2 was the predominant PG formed under all incubation conditions tested. Control samples produced measurable amounts of PGE2, and the measured level of this metabolite increased by 22-fold (from 7 to 152 ng/ml) following a 20 h treatment with the combination of TGF beta and tumor necrosis factor-alpha(TNF). The production of 6-keto-PGF1 alpha (the stable metabolite of prostacyclin) and of PGF2 alpha were each increased by about five-fold (from about 0.5 to 2.5 ng/ml) in samples treated with the cytokines. Thus, TGF beta and TNF exerted a regulation of hOB cell PG biosynthesis that was principally directed towards an increased PGE2 biosynthesis, with lesser effects on the production of other PG metabolites. COX-2 mRNA levels were increased within 2 h of cytokine stimulation, reached a maximum at 6-12 h, and levels had appreciably diminished by 24 h after treatment. Both TGF beta and TNF could independently increase COX-2 mRNA levels and PG biosynthesis. However, the increased production of PGE2 resulting from TNF stimulation was blocked by the addition of an interleukin-1 beta (IL-1 beta) neutralizing antibody, suggesting that TNF regulation of hOB cell PG synthesis was secondary to its capacity to increase hOB cell IL-1 beta production. TGF beta regulation of PG production was not affected by the addition of the neutralizing antibody. These studies support the proposition that PGs can be important autocrine/paracrine mediators of bone biology, whose production by hOB cells is responsively regulated by osteotropic cytokines.
Xu
J
J
Department of Biology, West Virginia University, Morgantown 26506-6057, USA.
Cissel
D S
DS
Varghese
S
S
Whipkey
D L
DL
Blaha
J D
JD
Graeber
G M
GM
Keeting
P E
PE
D000328:Adult; D001842:Bone and Bones / Q000378:metabolism*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D016207:Cytokines / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007118:Immunoassay; D010006:Osteoblasts / Q000378:metabolism*
D016207:Cytokines; D015232:Dinoprostone