Role of tumor necrosis factor-α in Gram-negative bacterial lipopolysaccharides induced implantation failure

Background and aims:  Gram-negative bacterial lipopolysaccharides (LPS) are known causative agents for pregnancy loss in mothers with genital tract infections. In this study, we attempt to test the role of tumor necrosis factor-α (TNF-α) in the normal physiological processes of preimplantation embryonic development and LPS induced pregnancy loss in mice. Since the preimplantation mouse embryos grow in an unattached state for a considerable period (day 1-4.5) of its development in the maternal environment, it is possible that a critical level of soluble and biologically active TNF-α is maintained in the maternal environment, and that any alteration in this could lead to implantation failure. Here we determine the pattern and level of expression of TNF-α gene in preimplantation stage embryos and uterus collected from control and LPS treated pregnant animals during different stages of preimplantation period of pregnancy by reverse transcriptase-polymerase chain reaction. Methods:  The concentrations and biological activity of soluble TNF-α protein present in oviductal fluid (OF) and uterine fluid (UF), in the normal and LPS treated animals, were determined by enzyme-linked immunosorbent assay and 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide assay on L929 cells, respectively. TNF-α was also given i.p. to study its effect on implantation. Results:  An early expression of TNF-α messenger ribonucleic acid in the preimplantation stage embryos collected from LPS treated animals was observed along with a significant rise in the level of biologically active soluble TNF-α in the OF. Similarly, the level of bioactive and soluble TNF-α present in the UF from LPS treated animals was significantly higher as compared to the control on day 4.42 of pregnancy. Conclusions:  TNF-α given i.p. exerted similar effects on pregnancy as that of LPS. An incessant exposure of the preimplantation stage embryos to significantly high levels of maternal bioactive free/soluble TNF-α, and an alteration in the normal pattern of its expression in the preimplantation stage embryos may be one of the causes of failure of implantation leading to poor pregnancy outcome in LPS treated mouse. (Reprod Med Biol 2005; 4: 79- 89).