Interferon epsilon is constitutively expressed in equine endometrium and up-regulated during the luteal phase.

The research article investigates the expression and regulation of Interferon epsilon (IFNE) in equine endometrium, finding that it is consistently expressed and increases during the luteal phase of the menstrual cycle. The study explores whether the expression is influenced by cycle phase or pregnancy, and the impact of estrogen and seminal plasma on IFNE levels.

Understanding Interferon epsilon (IFNE)

• Interferon epsilon (IFNE) is a type I interferon featured by its distinct expression profile and regulation compared to other type I interferons like interferon alpha and beta.
• Unlike its counterparts, the expression of IFNE is not stimulated by exposure to viral agents.
• It is expressed predominantly in mouse and human endometrium, specifically in luminal and glandular epithelial cells, and its expression levels increase with exposure to estrogen.

Study Objectives and Methodology

• The study aimed to determine if there is a cycle or pregnancy-dependent expression pattern of IFNE present in equine endometrium, and find the specific location of IFNE expression within the endometrium.
• It also sought to explore the effects of estrogen and seminal plasma on IFNE levels through an endometrial explant culture and culture of mixed epithelial and stromal cells.

Study Outcomes

• It was found that samples taken during diestrus and pregnancy showed significantly higher IFNE levels than samples from anestrous or estrous mares.
• The study also revealed that the exposure of mixed endometrial epithelial/stromal cell populations and endometrial explants to 10% seminal plasma and estradiol 17-beta did not have an impact on IFNE expression levels.
• IFNE expression was found only in luminal and glandular epithelial cells, and not in stromal cells. The expression in glandular epithelial cells was notably stronger during the diestrus and pregnancy phases compared to the anestrous and estrous phases.

Implications of the Findings

• The findings suggest that IFNE is part of the innate immune system in the endometrium, potentially protecting against uterine infections during the progesterone-dominated phase of the estrous cycle. This is suggested by the increase in IFNE levels during the luteal phase, which is progesterone-dominant.