Role of cytokines in progression of endometriosis

Peritoneal fluid in women with endometriosis contains an increased number of activated macrophages that secrete a variety of cytokines, including interleukin (IL)-6, IL-8, vascular endothelial growth factor, and tumor necrosis factor-alpha (TNF-alpha). Cytokines may be involved in the control of implantation and the growth of endometrial cells outside the uterus. In addition, several cytokines have been implicated in or directly associated with angiogenic activity in endometriosis. There could be a relationship between the levels of cytokines in the peritoneal fluid of patients with endometriosis and the status of the lesions in such patients. Peritoneal endometriosis can be classified as having red, black, or white lesions. Red lesions are known to be an active form of early endometriosis, because vascularization and mitotic activity are shown to be most prominent in these lesions. We found that the peritoneal fluid levels of TNF-alpha and IL-8 were significantly higher in patients with endometriosis, and correlated with the size and number of active lesions. In addition, TNF-alpha and IL-8 stimulated the growth of ectopic endometrial stromal cells. These cytokines with angiogenic activity may therefore have significant roles in the pathogenesis of endometriosis.

The potential role of stem cell factor and its receptor c-kit in the mouse blastocyst implantation

Embryo implantation is a complex process that requires the interaction of embryo and endometrium. Several growth factors and cytokines appear to be involved in this process. Stem cell factor (SCF) and its receptor c-kit regulate the proliferation and survival of germ cells and play an important role in follicular development. However, little information is available on the role of SCF and c-kit in the process of blastocyst implantation. In the present study, we examined the expression of SCF and c-kit mRNA in mouse embryos and in the stromal and epithelial cells of the uterine endometrium by reverse transcription-polymerase chain reaction (RT-PCR). SCF mRNA was expressed in the spreading blastocysts and endometrial cells, with especially strong expression occurring in the stromal cells. Expression of c-kit mRNA was detected in the blastocysts and spreading blastocysts, as well as in the endometrial cells. By immunocytochemical studies, staining for c-kit protein was observed in the in-vitro spreading trophoblasts. We found that 50-100 ng/ml SCF significantly promoted the expansion of the surface area of the spreading blastocysts (P < 0.01). These results are consistent with the hypothesis that SCF derived from endometrial cells and the implanting embryo exerts paracrine and/or autocrine action on the process of implantation by stimulating trophoblast outgrowth through its receptor c-kit.

Autocrine effects of transforming growth factor-alpha on the development of preimplantation mouse embryos

PURPOSE

We wished to explore the role of transforming growth factor (TGF)-alpha in mouse embryonic development.

METHODS

We examined the gene expression of TGF-alpha and epidermal growth factor receptor (EGFR) in mouse blastocysts by the reverse transcription-polymerase chain reaction and evaluated the effects of TGF-alpha on the development of preimplantation mouse embryos using TGF-alpha antisense oligodeoxynucleotide. Mouse teratocarcinoma F9 cells were also a subject of this study.

RESULTS

Gene transcripts of TGF-alpha and EGFR were present in both blastocysts and F9 cells. TGF-alpha significantly stimulated the rate of blastocoel expansion in early-cavitating blastocysts and the proliferation of F9 cells. Northern blot analysis showed that TGF-alpha gene expression in F9 cells was markedly suppressed in the presence of TGF-alpha antisense oligodeoxynucleotide. TGF-alpha antisense oligonucleotide significantly reduced the rate of blastocoel expansion and the growth of F9 cells. The inhibitory effects of TGF-alpha antisense oligonucleotide on blastocysts and F9 cells were reversed by the addition of TGF-alpha.

CONCLUSIONS

The present observations suggest that TGF-alpha acts as an autocrine factor in the development of preimplantation mouse embryos.

Expression of c-kit messenger ribonucleic acid in human oocyte and presence of soluble c-kit in follicular fluid

The c-kit protooncogene receptor and its ligand stem cell factor (SCF) regulate the proliferation and survival of germ cells as well as hematopoietic cells and melanocytes. In adult rodent ovary, c-kit and SCF play important roles in follicular development. However, little information about c-kit in the human ovary is available. In this study, we examined the expressions of c-kit messenger ribonucleic acid (mRNA) and c-kit protein in human oocytes, granulosa cells, and follicular fluid obtained from the women who underwent in vitro fertilization or laparoscopic examination. Expression of c-kit mRNA was detected by RT-PCR in the oocytes and granulosa cells. Western blot analysis showed the presence of soluble c-kit protein in the follicular fluid, and lower levels of c-kit protein were detected in the granulosa cells and the supernatant of granulosa cell cultures. The concentration of soluble c-kit in follicular fluid measured by enzyme-linked immunosorbent assay showed significant correlation with fluid volume and follicular fluid concentrations of estradiol, testosterone, and androstenedione. In summary, we found for the first time the presence of c-kit mRNA and soluble c-kit protein in human oocytes and follicular fluid. The results suggested that in human ovary, c-kit may play an important role in follicular development.