| ObjectiveSuccessful implantation is very important for the pregnancy of species. It isnot only a complex and intricate cross-talk between the embryonic andmaternal tissues, but also an absolute requirement for the development ofembryos. A series of stages are included in the process of implantation: anormal and functional embryo which developed to the blastocyst stage,maternal endometrium during the window of implantation(ready to acceptthe blastocyst), trophoblast adhesion, penetration and invasion. IK cytokine,a19KD factor coded by IK gene localized on chromosome2p15-p14, wasfirst isolated and purified from the conditioned culture medium of theleukemic cell line K562. It was reported that IK cytokine inhibited bothMHC Ⅱ constitutive and IFN-γ-induced expression. IK cytokine has closerelationship with the expression of MHC Ⅱ. Up to now, there are notrelevant articles defined whether IK cytokine plays a role in thefetomaternal immune torerance during pregnancy. Thus, the aims of thisstudy were to detect IK cytokine expression in mouse uterus of earlypregnancy to confirm its nature in implantation, and to provide theoretical evidence for the mechanism of implantation and preventive and therapeuticmethods of pregnancy failure.Methods1. Real-Time PCR: To analyse IK cytokine mRNA level in miceendometria during early pregnancy(D1-D7) and MHC Ⅱ expression in miceuterus before and after treatment with IK cytokine A-ODNs on D4and D5.2. Western blot: To detect IK cytokine protein in mice endometria duringearly pregnancy(D1-D7), between implantation site and inter-implantationsegment,24h and48h after treatment with IK cytokine A-ODNs and IKcytokine S-ODNs and examine MHC Ⅱ expression in mice uterus beforeand after treatment with IK cytokine A-ODNs on D4and D5.3. Immunohistochemistry: To detect IK cytokinein in mice endometrialduring early pregnancy(D1-D7), pseudopregnancy(PD1-PD7) and its levelbefore and after treatment with IK cytokine A-ODNs.4.Uterine horns injection of IK cytokine A-ODNs: To detect the effect ofA-ODNs on embryo implantation.Results1. The expression of IK cytokine mRNA increased gradually from D1toD4of pregnancy and reached a peak level on D4of pregnancy(P<0.05).2. Western blot and Immunohistochemical analysis revealed that theexpression of IK cytokine protein increased gradually from D1to D5ofpregnancy and reached a peak level on D5of pregnancy(P<0.05).3. The expression of IK cytokine at the implantation site was much stronger than that in the inter-implantation segment on D5.4. The expression of IK cytokine was significantly lower in thepseudopregnant uterus than that in the normal uterus and never reach peakduring the whole pseudopregnancy.5. After24h and48h(on D4and D5) of intrauterine injection with IKcytokine A-ODNs on D3, the expression of IK cytokine in the uterus wasremarkably inhibited, while the expression of MHC Ⅱ increased and thenumber of implanted embryos significantly reduced (P<0.05).ConclusionThe expression of IK cytokine in mouse endometria reached a peak level at“implantation window”, but a significant reduction of its protein expressionand a remarkable increase of MHC Ⅱ expression were observed on D4andD5(implantation window) after treatment with IK A-ODNs on D3, and asignificant decrease of the number of implanted embryos was also found.These findings suggested that the suppression of MHC Ⅱ antigens by IKcytokine was likely to inhibit the fetal-maternal immune response,contributing to maternal immune tolerance of conceptus and themaintenance of successful pregnancy. When the expression of MHC Ⅱ wasno longer suppressed because of the inhibition of IK cytokine expression, itwill result in attacking maternal immune system against fetus andinfluenced embryo implantation. However, embryo implantation has notbeen completely inhibited by suppressing the expression of IK cytokine, implying involvement of certain other mechanisms participating in theregulation of fetal-maternal immune tolerance, which remains to be furtherinvestigated. |
PDF Full Text Request