Preterm labor and bacterial intraamniotic infection:: Arachidonic acid liberation by phospholipase A2 of Fusobacterium nucleatum

OBJECTIVE: The studies presented in this report were undertaken to evaluate whether Fusobacterium nucleatum, a common anaerobic isolate in intrauterine infection, stimulates arachidonic acid metabolism a rate-limiting step for prostaglandin synthesis, in the human uterine endometrium. STUDY DESIGN: Effects of F nucleatum on arachidonic acid liberation from human uterine endometrial cells and of F nucleatum extract on lysophosphatidylcholine production in human uterine endometrial cells were investigated. RESULTS: When human uterine endometrial cells labeled with tritiated arachidonic acid to an isotopically steady state were exposed to an extract of F nucleatum, arachidonic acid liberation was stimulated, accompanied by lysophospholipid formation. Similar stimulatory effects on phospholipid degradation were also observed in the experiment with bacterially conditioned media. CONCLUSIONS: These results suggest that F nucleatum stimulates endometrial phospholipid metabolism, related to activity of phospholipase A(2), which might induce the onset of labor associated with intraamniotic infection.