Cytokine changes and embryo attachment in mouse endometrial cells following treated with peripheral blood mononuclear cells(PBMCs)expressing ectopic hCG,and hCG-activated PBMCs

Objective:To compare the effect of human chorionic gonadotropin(hCG)-producing peripheral blood mononuclear cells(PBMCs)and PBMCs activated by hCG in vitro and expressions of related immune genes in mouse implantation.Methods:hCG-producing PBMCs(transfected PBMC)and PBMCs activated by hCG in vitro were introduced into isolated mouse endometrial cells,while cell cultures were divided into four groups:the control,PBMC,transfected,and activated PBMC groups.The expression of studied genes(IL-1β,IL-6,Lif,and Vegf)was evaluated and blastocyst attachment on the cocultured cells(isolated endometrial cells and PBMC cells)was monitored in all four groups.Results:Data showed that expression decreased in the PBMC group compared to the treated PBMC(transfected and activated PBMCs)and increased in transfected PBMC compared to the activated PBMC.Attachment and migration of blastocysts were dramatically enhanced in the transfected PBMC group compared to the activated PBMC group(P<0.05).Conclusions:Use of hCG-producing PBMCs(transfected PBMC)has more influence on endometrial receptivity.

Attenuated retinoic acid signaling is among the early responses in mouse uterus approaching embryo attachment

The uterus is transiently receptive for embryo implantation.It remains to be understood why the uterus does not reject a semi-allogeneic embryo(to the biological mother)or an allogeneic embryo(to a surrogate)for implantation.To gain insights,we examined uterine early response genes approaching embryo attachment on day 3 post coitum(D3)at 22 hours when blue dye reaction,an indication of embryo attachment,had not manifested in mice.C57BL/6 pseudo-pregnant(control)and pregnant mouse uteri were collected on D3 at 22 hours for microarray analysis.The self-assembling-manifold(SAM)algorithm identified 21,858 unique probesets.Principal component analysis indicated a clear separation between the pseudo-pregnant and pregnant groups.There were 106 upregulated and five downregulated protein-coding genes in the pregnant uterus with fold change(fc)>1.5 andq value<5%.Gene ontology(GO)analysis of the 106 upregulated genes revealed 38 significant GO biological process(GOBP)terms(P<0.05),and 32(84%)of them were associated with immune responses,with a dominant natural killer(NK)cell activation signature.Among the top eight upregulated protein-coding genes,Cyp26a1 inactivates retinoic acid(RA)whileLrat promotes vitamin A storage,both of which are expected to attenuate RA bioavailability;Atp6v0d2 andGjb2 play roles in ion transport and transmembrane transport;Gzmb,Gzmc,andIl2rb are involved in immune responses;andTdo2 is important for kynurenine pathway.Most of these genes or their related pathways have functions in immune regulations.RA signaling has been implicated in immune tolerance and immune homeostasis,and uterine NK cells have been implicated in immunotolerance at the maternal-fetal interface in the placenta.The mechanisms of immune responses approaching embryo attachment remain to be elucidated.The coordinated effects of the early response genes may hold the keys to the question of why the uterus does not reject an implanting embryo.

Transforming growth factor-α promotes mouse blastocyst outgrowth and secretion of matrix metalloproteinases

Objective To study the effect of transforming growth factor-α (TGF-α) on early stage of embryo implantation.Methods Mouse blastocysts were cultured in vitro in medium containing various concentrations of TGF-α. Blastocyst implantation capacity was evaluated by calculating the percentage of embryos with attachment or outgrowth. Matrix metalloproteinases (MMPs) secretion of blastocysts was observed using gelatin zymography. Results There was no significant difference in the percentage of attachment between control and TGF-α treated groups, but the percentage of outgrowth of TGF-α treated groups was significantly higher than that of the control group after 24h culturing. Gelatin zymography showed that blastocysts cultured in TGF-α treated groups started secreting MMPs earlier than those in the control group.Conclusion TGF-α is involved in regulating the mouse embryo implantation process by promoting blastocyst outgrowth and secreting matrix matalloproteinases.