Endometrial expression of members of the IL-1 family: their involvement in delayed conception of dairy cows.

The cytokines of the interleukin-1 (IL-1) family are closely involved in the resolution of inflammation in cows with metritis and endometritis. However, little is known about the role of these cytokines beyond uterine regression in the absence of disease, especially around conception. Thus, the aim of this study was to examine the gene and protein expression of IL-1α, IL-1β, IL-1RI, IL-1RII and IL-1Ra in endometrial biopsies previous to conception, to evaluate the possible association of these cytokines with delayed conception in dairy cows. Gene and protein expression levels were evaluated by real-time PCR and immunohistochemistry, respectively. The gene expression levels of cytokines were not associated with the duration of the period to conception following parturition. However, high protein expression of IL-1β and low protein expression of IL-1Ra were significantly associated with early conception. These results suggest that an imbalanced protein expression of IL-1β and IL-1Ra in the endometrium of dairy cows could be part of the maternal immune response mechanism necessary to propitiate early conception and probably to maintain pregnancy.