Prostaglandin E2 stimulates the production of interleukin-6 by neonatal mouse parietal bones.
The pleiotropic cytokine interleukin-6 (IL-6) is thought to be involved in bone homeostasis. A number of bone resorbing agents have been shown to induce the release of IL-6 from bone. We wished to determine whether prostaglandin E2 (PGE2), which is a mediator of bone resorption, can elicit the production of IL-6. IL-6 was measured by the proliferative response of B9 hybridoma cells and could be completely neutralised by an anti-IL-6 antibody. Parietal bones from neonatal mice were maintained in culture in the presence of indomethacin (10(-6) M) with or without PGE2. The time course and dose-response to PGE2 of IL-6 production were determined. After 6 h in culture, 10(-8) M PGE2 produced significantly more IL-6 than the controls (P < 0.005). PGE2 (10(-6) M) stimulated the production of a mean of 12.8 ng/ml IL-6 over 6 h. Preincubating bones with indomethacin for 20 h prior to a 6 h culture with indomethacin led to a lowering of the production of IL-6 (mean 1.8 ng/ml) compared to bones cultured without the preincubation period (5.8 ng/ml). When the indomethacin preincubation period was used, a significant increase in IL-6 production was found with 10(-9) M PGE2 (P < 0.005), and 10(-6) M PGE2 caused the production of 39.9 ng/ml IL-6 over 6 h. Stripping endocranial and ectocranial membranes from bones demonstrated the membranes to be the major site of IL-6 production. However, intact bones were required for maximal stimulated IL-6 production.
Holt
I
I
Charles Salt Research Centre, Robert Jones and Agnes Hunt Orthopaedic and District Hospital, Oswestry, Shropshire, UK.
Davie
M W
MW
Braidman
I P
IP
Marshall
M J
MJ
D000818:Animals; D000831:Animals, Newborn; D001681:Biological Assay; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006825:Hybridomas; D007213:Indomethacin / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000494:pharmacology; D051379:Mice; D008808:Mice, Inbred CBA; D010294:Parietal Bone / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D015850:Interleukin-6; D003513:Cycloheximide; D015232:Dinoprostone; D007213:Indomethacin