Polarised bovine endometrial epithelial cells vectorially secrete prostaglandins and chemotactic factors under physiological and pathological conditions

Abstract

Epithelial cells of the endometrium secrete prostaglandins to regulate the bovine oestrous cycle and form a functional barrier to microbes. However, bacterial infection of the endometrium commonly causes infertility in dairy cattle by disrupting endometrial physiology. Epithelial cell cultures are used to study the mechanisms of physiology and pathology, but 2D cultures may not reflect the 3D complexity of the epithelium. In this study, a polarised epithelial cell transwell culture was developed, using transepithelial resistance (TER), to monitor epithelial integrity. Polarised epithelial cells were treated with oxytocin and arachidonic acid to test physiological function and with lipopolysaccharide (LPS) to mimic bacterial infection. Supernatants were analysed for prostaglandin E2(PGE), prostaglandin F2α, the chemokine interleukin-8 (IL8) and the ability of supernatants to induce neutrophil migration. Confluent epithelial cells established polarity when TER was >1800 Ωcm2and predominantly released prostaglandins basolaterally. In contrast, IL8 from epithelial cells accumulated apically and the supernatants were highly chemotactic for neutrophils. The striking exception was when the epithelial cells were treated with LPS in the apical or basolateral compartment independently, which led to the release of IL8 towards the treated compartment. Although stromal cells also accumulated PGE and IL8 in response to treatment, co-culture of stromal cells in the well below polarised epithelial cells did not influence cellular responses. In conclusion, polarised endometrial epithelial cells vectorially released prostaglandins and chemokines to reflect their respective mechanistic roles in physiology and pathology.