Lipopolysaccharide-binding Protein Involved in Process of Mouse Embryo Implantation and Decidualization of Endometrial Stromal Cells

Lipopolysaccharide-binding protein (LBP) functions as an acute phase protein and plays a role in the innate immune response to bacterial challenge.To investigate the uterine expression of LBP during peri-implantation in mice,in situ hybridization and immunohistochemical staining were used to detect the mRNA and protein expression of LBP in mouse uteri in the early pregnancy,pseudopregnancy,artificial decidualization and hormone-treated mice.The results showed that LBP was expressed in uterine luminal epithelium (LE) and glandular epithelium (GE) during days 1-4 of pregnancy.During days 5-8,LBP was weakly expressed in the decidual cells around the embryo on the 5th day of pregnancy (implantation occurred),then gradually increased,LBP was strongly expressed in the decidual zone on the 8th day of pregnancy.The expression of LBP in pseudopregnancy was similar with pregnancy on days 1-4.In artificial decidualization mice,LBP was observed in uterine LE and GE in the control horn,whereas LBP expression was significantly higher in decidua of mouse uteri under artificial decidualization.In hormone-treated mice,the expression of LBP wasup-regulated by 17β-estradiol (E) and progesterone (P).In addition,the cultured mouse endometrial stromal cells (mESCs) were induced for in vitro decidualization with 10 nmol·LEand 1 μmol·LP.Real-time PCR results showed that LBP mRNA expression was highly induced in mESCs after decidual stimulus.In vivo and in vitro experiments showed that LBP was expressed in the decidual cells,indicating that LBP involved in decidualization of mouse uteri.