Inactivation of porcine interleukin-1β results in failure of rapid conceptus elongation

Significance Establishment of pregnancy in pigs requires that conceptuses produce estrogen to maintain functional corpora lutea throughout gestation and rapidly elongate to provide adequate surface area for nutrient flow through its epitheliochorial placenta. Early conceptus development in the pig is unique in that conceptuses rapidly elongate to long filamentous threads within 1 to 2 h. Conceptus IL1B2 gene and protein expression increase during the period of conceptus elongation. Using the CRISPR/Cas9 gene-editing system, we successfully knocked out pig conceptus IL1B2 expression and demonstrate that conceptus elongation was inhibited. This research provides insight into the biological role of IL1B2 in pig conceptus development and demonstrates the use of the CRISPR/Cas9 gene-editing system to evaluate genes during early conceptus development.