Cytokine regulation of adult human osteoblast-like cell prostaglandin biosynthesis

✍ Scribed by JiaQuan Xu; David S. Cissel; Samuel Varghese; Diana L. Whipkey; J. David Blaha; Geoffrey M. Graeber; Philip E. Keeting

• Book ID: 101261108
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 238 KB
• Volume: 64
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19970315)64:4<618::aid-jcb10>3.0.co;2-8

✦ Synopsis

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. PGE 2 was the predominant PG formed under all incubation conditions tested. Control samples produced measurable amounts of PGE 2 , 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 TGFb and tumor necrosis factor-a(TNF). The production of 6-keto-PGF 1a (the stable metabolite of prostacyclin) and of PGF 2a were each increased by about five-fold (from about 0.5 to 2.5 ng/ml) in samples treated with the cytokines. Thus, TGFb and TNF exerted a regulation of hOB cell PG biosynthesis that was principally directed towards an increased PGE 2 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 TGFb and TNF could independently increase COX-2 mRNA levels and PG biosynthesis. However, the increased production of PGE 2 resulting from TNF stimulation was blocked by the addition of an interleukin-1b (IL-1b) neutralizing antibody, suggesting that TNF regulation of hOB cell PG synthesis was secondary to its capacity to increase hOB cell IL-1b production. TGFb 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.