Evidence that PGI2-generation in human dental cysts is stimulated by leucotrienes C4 and D4

Various prostaglandins, particularly PGE2 and PGI2, appear to play a major role in osteolytic processes. The bone-destructive action of dental squamous cell cysts is thought to be caused or at least mediated by prostaglandins. Both leucotrienes and prostaglandins are synthesized from a common precursor substance, i.e. arachidonic acid, in a series of reactions. There is a special relation between leucotrienes and PGI2 in that PGI2 synthesis in endothelial cells can be enhanced by LTC4 and LTD4. R-TLC showed conversion of the arachidonic acid added into PGI2 in 8 out of 12 cases, as reflected by the stable degradation product 6-oxo-PGF1 alpha. In 8 cases bioassay showed PGI2 synthesis without addition of LTC4 and LTD4. Incremental LTC4 and LTD4 additions were found to cause a highly significant increase of PGI2 synthesis rates. In summary, LTC4 and LTD4 stimulate PGI2 synthesis in chronic inflammatory processes in vivo and may thus elicit or accelerate osteolysis.