Enhanced expressions of endometrial tumour necrosis factor alpha and its receptors during early pregnancy in bonnet monkeys

Tumour necrosis factor alpha (TNF-α), a pro-inflammatory cytokine may play an active role in stimulating inflammatory reactions during pregnancy. However, the expression of endometrial TNF-α has not been investigated especially during early pregnancy, a phenomenon invariably accompanied by inflammatory reaction. In the present study, the endometrial expressions of TNF-α and its receptors (TNFR1 and TNFR2) during early pregnancy, when the embryo lies free in the zona hatched state in the uterine lumen, were analyzed by immunohistochemistry. The endometrial expressions of TNF-α, TNFR1 and TNFR2 were found to be significantly up-regulated (p < 0.05) in the glandular epithelium on day 6 post-ovulation in pregnant animals. The alteration in the expression of these molecules may contribute to the induction of local inflammatory reactions during implantation.