Preimplantation factor (PIF) promoting role in embryo implantation: increases endometrial integrin-α2β3, amphiregulin and epiregulin while reducing betacellulin expression via MAPK in decidua.
BACKGROUND
Viable embryos secrete preimplantation factor (PIF), a peptide that has autocrine effects where levels correlate with cultured embryos development. sPIF (PIF synthetic analog) promotes implantation by regulating decidual-cells immunity, adhesion, apoptosis and enhances trophoblastic cell invasion. Herein sPIF priming effects on non-decidualized endometrium and decidualized-stroma are investigated, assessing elements critical for effective embryo-maternal cross-talk, prior to and at implantation.


METHODS
We tested sPIF effect on human non-pregnant endometrial epithelial and non-decidualized stroma α2β3 integrin expression (IHC and flow cytometry), comparing with scrambled PIF (PIFscr-control). We examined sPIF effect on decidualized non-pregnant human endometrial stromal cells (HESC) determining pro-inflammatory mediators expression and secretion (ELISA) and growth factors (GFs) expression (Affymetrix global gene array). We tested sPIF effect on HESC Phospho-kinases (BioPlex) and isolated kinases activity (FastKinase).


RESULTS
sPIF up-regulates α2β3 integrin expression in epithelial cells, (P < 0.05) while PIFscr had no effect. In contrast, in stromal cell cultures sPIF had no effect on the same. In HESC, sPIF up-regulates pro-inflammatory cytokines; IL8, IL1β and IL6 expression. The major increase in GRO-α, ICAM-1 and MCP-3 expression is coupled with same ligands secretion (P < 0.05). sPIF modulates in HESC GFs expression: up-regulates amphiregulin and epiregulin- critical for implantation and enhances several fibroblast growth factors (FGF) relevant for decidual function. In contrast, sPIF down-regulates major pro-proliferative ligands, betacellulin and IGF1 expression. sPIF modulatory effect on GFs is exerted by down-regulating pro-proliferative phospho-activated MAPkinases, p-MEK1 and p-ERK (P < 0.01, P < 0.04, respectively). Stress-induced p-38-MAPK (P = 0.04) and c-Jun kinase signaling involved MAPK8IP2 (-2.1 fold) expression decreased which protects against reactive oxygen species. Although pro-inflammatory p-NFkB (P = 0.06) decrease was mild, its promoter TNFRS11 expression markedly (-25-fold) decreased. In contrast, anti-proliferative phosphatases PTPRZ1 and PPP2R2C expression increased.


CONCLUSIONS
sPIF post-fertilization primes endometrial-epithelium, while during implantation creates a beneficial pro-inflammatory milieu. PIF acts by balancing decidual pro-implantation properties while controlling excessive pro-proliferative and inflammatory signals expression. Overall, PIF influences critical peri-implantation events in a sequential coordinated fashion which facilitates embryo implantation.
SIEP - Society for the Investigation of Early Pregnancy, 1697 Lark Lane, Cherry Hill, NJ 08003, USA. barnea@earlypregnancy.org
Eytan R
ER
Barnea
David
D
Kirk
Michael J
MJ
Paidas
D000595:Amino Acid Sequence; D066258:Amphiregulin; D066259:Betacellulin; D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D003656:Decidua / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D066255:EGF Family of Proteins; D004717:Endometrium / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000096:biosynthesis*; D066260:Epiregulin; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000096:biosynthesis*; D006801:Humans; D039421:Integrin alpha2 / Q000096:biosynthesis*; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*
C587848:AREG protein, human; D066258:Amphiregulin; C587851:BTC protein, human; D066259:Betacellulin; D066255:EGF Family of Proteins; C587880:EREG protein, human; D066260:Epiregulin; D006023:Glycoproteins; C056564:ITGA2B protein, human; D039421:Integrin alpha2; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C569738:preimplantation factor, synthetic; D004815:Epidermal Growth Factor; D048051:p38 Mitogen-Activated Protein Kinases