Cytokines tumor necrosis factor-α and interferon-γ participate in modulation of the equine corpus luteum as autocrine and paracrine factors.

The research study examines the role of two cytokines, tumor necrosis factor alpha (TNF) and interferon gamma (IFNG), in influencing corpus luteum (CL) function in mares. It was found that these cytokines acted as autocrine and paracrine factors, impacting the function and viability of the CL throughout the luteal phase.

Research Aim and Methodology

• The main aim of the study was to gain better understating of how the corpus luteum (CL) function in the mare is regulated.
• To determine this, the researchers focused on two specific cytokines: tumor necrosis factor alpha (TNF) and interferon gamma (IFNG), and their respective receptors (TNFRI, TNFRII and IFNRI).
• The effect of these cytokines on the CL at different stages of the luteal phase was studied.
• The researchers used in vitro studies to determine the impact of TNF and IFNG on the secretion functions and viability of luteal cells.

Findings

• It was found that cytokine ligands and receptors were present in both steroidogenic and endothelial cells.
• Protein expression for TNF was observed to be greater in mid-phase and regressing CL, with an increase in TNFRI in regressing CL while TNFRII remained unchanged.
• The highest expression for IFNG and IFNRI was seen in regressing CL.
• The transcription of mRNA for TNF increased from the mid-phase to the regressing CL, and both TNFRI and TNFRII decreased from early to regressing CL.
• The transcription of mRNA for IFNG was lower in the early phase CL as compared to mid or regressing luteal phase, while IFNRI expression remained unchanged.
• The researchers found that in the early CL, TNF increased the secretion of P(4) and PGE(2) but decreased PGF(2α) secretion. However, in the mid luteal phase, TNF increased PGF(2α) secretion while the combination of TNF and IFNG decreased PGE(2) secretion. In the regressing phase, all three combinations of TNF, IFNG and TNF+IFNG decreased P(4) and PGE(2) secretion, and at the same time, TNF and TNF+IFNG increased PGF(2α) secretion by luteal cells.
• The cell viability was seen to be reduced by TNF+IFNG in the regressing CL.

Conclusion

• The data obtained hinted at the presence of cytokines TNF and IFNG along with their receptors in the equine CL, suggesting that they potentially play a role in the regulation of luteal function.