Effect of cytokines and ovarian steroids on equine endometrial function: an in vitro study.

This study investigates how certain immune system molecules (cytokines) and ovarian hormones interact and influence the function of the endometrium in horses. The research was conducted in vitro (outside of a living organism) and found out the changes in the presence of these molecules throughout a mare’s oestrous cycle, as well as the hormonal responses of the endometrium to these molecules.

Objectives of the Study

• The research had two main aims: firstly to scrutinize the presence of certain cytokines and their receptors in the mare endometrium throughout the oestrous cycle; Secondly it aimed to evaluate the hormonal secretion (prostaglandins), angiogenic activity, and cell viability in response to these immune molecules, as well as certain ovarian hormones.

Findings of the Study

• The transcription level of the cytokines TNF and FASLG increased during the early and late luteal phase, whereas the transcription of IFNG increased in the late luteal phase. The transcript of both TNF receptors was most evident in the mid-luteal phase.
• The cytokines and their receptors were expressed in various components of the endometrium – surface and glandular epithelium as well as in the stroma.
• Expression trends of these immune molecules and their receptors varied throughout the oestrous cycle. For instance, the expression of TNF and TNFRSF1A increased during the follicular phase and mid-Luteal phase, while others like FASLG and FAS showed the highest expression in the late luteal phase.
• The researchers found that oxytocin (OXT) elevated the secretion of certain prostaglandins in the follicular and mid-luteal phase. Another observation was increased prostaglandin secretion in response to estradiol and a combination of progesterone and estradiol in the mid-luteal phase.
• The cytokine TNF and hormone progesterone were found to enhance cell viability.
• Implementation of all treatments excluding progesterone led to increased nitric oxide and angiogenic activity in both the follicular and luteal phase.

Significance of the Findings

• The findings suggest that there seems to be a coordinated action of cytokines and ovarian hormones that could be regulating various functions in the equine endometrium – secretory, angiogenic, and proliferative. This highlights a strong connection between the immune-endocrine interactions in the equine endometrium.