PTGS2 and infection: Endometrial epithelial cells, as the first line of defense, can initiate an immune reaction by increased synthesis of different cytokines [interleukin 1A (IL1A), IL6, IL8, and CXC ligand 3 (CXCL3)] and prostaglandin endoperoxide synthase 2 (PTGS2; Amos et al., 2014; Turner et al., 2014; Gärtner et al., 2016), leading to an influx of immune cells to the site of infection (Takeuchi and Akira, 2010).