Evidence for the presence of N-formyl-methionyl-leucyl-phenylalanine (fMLP) receptor ligands in human amniotic fluid and fMLP receptor modulation by physiological labour.
OBJECTIVE
The presence of amniotic binding sites for N-formyl-methionyl-leucyl-phenylalanine (fMLP), an inflammatory peptide, and its ability to induce prostaglandin E2 synthesis in the human amnion prompted us to investigate for: (1) the presence of fMLP receptor ligands (fMLPRL) in the amniotic fluid; (2) expression of the fMLP receptor in amniotic tissue; (3) the effect of amniotic fMLPRL on neutrophil cyclic AMP (cAMP) level and calcium concentration ([Ca2+]i) during physiological pregnancy and labour.


METHODS
Binding assays were performed on neutrophils to determine the presence of fMLRL in the amniotic fluid at the 17th week of pregnancy, as well as at term, before and after the onset of labour. The expression of fMLP receptor mRNA was evaluated by RT-PCR, the cAMP level by a radiochemical assay, and the calcium concentration by Fura-2 AM fluorescence measurement.


RESULTS
fMLPRLs were detectable in amniotic fluid throughout pregnancy, and their levels did not vary during gestation. Labour significantly increased both the amniotic fMLPRL level and the expression of fMLP receptor in amnion tissue. The increased amniotic fMLPRL concentration noted during labour significantly increased neutrophil cAMP level and [Ca2+]i.


CONCLUSIONS
These findings demonstrate for the first time the presence of fMLP receptor ligands in amniotic fluid, and indicate a modulation of the fMLP system by the events of physiological labour.
Biondi
Carla
C
Department of Biology, University of Ferrara, 44100 Ferrara, Italy. clm@dns.unife.it
Pavan
Barbara
B
Dalpiaz
Alessandro
A
Valerio
Alessandra
A
Spisani
Susanna
S
Vesce
Fortunato
F
D000653:Amniotic Fluid / Q000276:immunology*; D001681:Biological Assay / Q000379:methods; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000276:immunology*; D008024:Ligands; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000032:analysis / Q000276:immunology*; D009504:Neutrophils / Q000166:cytology / Q000276:immunology; D011247:Pregnancy / Q000276:immunology*; D012333:RNA, Messenger / Q000276:immunology; D044042:Receptors, Formyl Peptide / Q000032:analysis / Q000276:immunology*
D008024:Ligands; D012333:RNA, Messenger; D044042:Receptors, Formyl Peptide; D009240:N-Formylmethionine Leucyl-Phenylalanine