Tumour necrosis factor-alpha (TNF-alpha) in human endometrium and uterine secretion: an evaluation by immunohistochemistry, ELISA and semiquantitative RT-PCR

Tumour necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine synthesi zed throughout the female reproductive tract. Even though evidence has accu mulated that supports its role in autocrine and paracrine processes, its ex pression and function in the human endometrium are still not completely und erstood. To gain a better understanding of the synthesis and release of TNF -alpha in the endometrium and how this relates to concentrations in uterine secretion, its expression throughout the menstrual cycle was investigated by three different techniques. Samples of endometrial tissue and uterine se cretions were collected from patients undergoing abdominal and vaginal hyst erectomy for benign reasons. The mRNA expression of TNF-alpha was investiga ted in homogenized endometrial tissue by semiquantitative reverse transcrip tion-polymerase chain reaction (RT-PCR) (n = 18). An assessment of the cell ular TNF-alpha protein localization in the endometrial glands was performed immunohistochemically (n = 39). The concentrations of the secreted TNF-alp ha protein in endometrial secretion were determined by enzyme-linked immuno sorbent analysis (n = 30). All three methods gave similar results on the te mporal expression of TNF-alpha mRNA and TNF-alpha protein during the cycle. Concentrations of endometrial TNF-alpha mRNA in tissue samples and TNF-alp ha protein in uterine secretion were quite low at the beginning of the cycl e, rose sharply in the mid- to late proliferative phase and decreased towar ds the end of the cycle. The concentrations of TNF-alpha protein in the end ometrial glands, as shown by immunohistochemical investigation, stayed high throughout the secretory phase at values slightly below those of the late proliferative phase.