Factors affecting fertilization: endometrial placental protein 14 reduces the capacity of human spermatozoa to bind to the human zona pellucida.
OBJECTIVE
To examine whether placental protein 14 (PP14) may affect directly those sperm functions crucial to fertilization and early embryo development.


METHODS
In these prospective studies, we evaluated semen samples of fertile men incubated under capacitating conditions with and without PP14.


METHODS
Academic tertiary institution.


METHODS
Biologically active PP14 was purified from human midtrimester amniotic fluid by anion exchange and immunoaffinity chromatography. After separation of the motile fraction, spermatozoa were incubated for 30 minutes with or without PP14 (concentration range of 0.01 to 100 micrograms/mL), washed, and then aliquots were prepared for use in the different assays. Human sperm-zona pellucida (ZP) binding was assessed using the hemizona assay (HZA) in a 4-hour gametes coincubation period. Sperm motility parameters were evaluated using a computerized semen analyzer. The acrosome reaction (AR) was determined by fluorescein isothiocyanate-conjugated Pisum sativum agglutinin and indirect immunofluorescence.


METHODS
Sperm-ZP binding, sperm motility patterns, and AR.


RESULTS
Preincubation of sperm (and not the hemizonae) with PP14 produced a significant and dose-dependent inhibition of binding in the HZA. Monoclonal antibodies generated against PP14 showed no direct effect in the HZA and partially neutralized the inhibitory activity of PP14 in the HZA. Insulin-like growth factor binding protein-1 (IGFBP-1), an endometrial stromal cell product, showed no effect in the HZA. Neither PP14 nor IGFBP-1 interfered with sperm motility parameters or the AR.


CONCLUSIONS
Placental protein 14 produced a potent, fast, and dose-dependent inhibition of binding of human spermatozoa to the human ZP without affecting other prefertilization events (i.e., hyperactivated motility or AR). The detrimental effect on sperm-zona interaction seems to be specific for this endometrial epithelial protein (not observed with an endometrial stromal product) and may have fundamental bearance to the fertilization process thus providing a mechanism for endometriosis-related infertility.
Oehninger
S
S
Jones Institute for Reproductive Medicine, Eastern Virginia Medical School, Norfolk.
Coddington
C C
CC
Hodgen
G D
GD
Seppala
M
M
D000177:Acrosome / Q000187:drug effects / Q000502:physiology; D000653:Amniotic Fluid / Q000737:chemistry; D000001:Calcimycin / Q000494:pharmacology; D002352:Carrier Proteins / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects*; D005455:Fluorescent Antibody Technique; D000071816:Glycodelin; D006023:Glycoproteins; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1; D008297:Male; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D011446:Prospective Studies; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism; D015044:Zona Pellucida / Q000378:metabolism*
D002352:Carrier Proteins; D000071816:Glycodelin; D006023:Glycoproteins; D018970:Insulin-Like Growth Factor Binding Protein 1; C045246:PAEP protein, human; D011257:Pregnancy Proteins; D000001:Calcimycin