The presence of interleukin-1beta in the bovine reproductive tract

Interleukin-1 (IL-1) is a pleiotropic cytokine implicated in endometrial and embryonic physiology. Our objective was to determine the presence of IL-1 in the endometrium, oviduct, and uterine fluid of cows at days 0, 7, and 14 of the estrous cycle. Immunoreactive IL-1beta was identified in endometrial and oviductal tissues throughout the estrous cycle by immunohistochemistry. Both glandular and luminal endometrial epithelium exhibited intense IL-1beta staining. For luminal epithelium, staining was strongest at day 0 and least at day 7. Staining in glandular epithelium was similar at all stages of the estrous cycle examined. There was a diffuse immunostaining throughout the endometrial stroma, and some isolated stromal cells stained strongly, as did endothelial cells. Immunoreactive IL-1beta was detected in uterine flushings by Western blotting, and the frequency of positive samples and intensity of immunoreactive bands did not differ between days of the estrous cycle. In the oviduct, immunoreactive IL-1beta was found in the epithelium and stroma of ampulla and isthmus. The staining intensity score for the oviduct was not different between isthmus and ampulla or between days of the estrous cycle. The presence of IL-1beta in the bovine endometrium, oviduct, and uterine flushings supports the idea that this cytokine may play an important role in regulating embryonic and endometrial function in cattle.