Expression of proinflammatory cytokines IL-1β, IL-6 and TNFα in the retained placenta of mares.

The research article focuses on the connection between proinflammatory cytokines and postpartum disease in horses, particularly retained fetal membranes (RFM). It finds that higher levels of certain cytokines may be related to RFM and suggests further research to fully understand the role of these proteins during equine parturition.

Introduction to the Study and Hypothesis

• The researchers began by noting the problem of retained fetal membranes (RFM) as a common postpartum disease in mares. This condition occurs when the placenta, which houses and supports the fetus during pregnancy, does not fully expel after giving birth.
• The possible cause of RFM, according to the researchers, could be an irregular inflammatory response involving proinflammatory cytokines. These are proteins that aid in immune responses including the onset of inflammation. They are released during the birthing process to enhance uterine contractions and facilitate expulsion of the fetus and fetal membranes.

Methods of the Study

• The team collected samples from both the endometrium (inner lining of the uterus) and the allantochorion (fetal sac within the placenta) of 15 mares with RFM and 29 control mares, within 2 hours of foal delivery.
• The mRNA expression of the proinflammatory cytokines IL-1β, IL-6, and TNFα in these samples were analyzed using Real Time PCR and Western blot – laboratory techniques for determining gene and protein expression.
• An additional process used was immunocytochemistry, which visualizes and locates specific proteins in cells.

Results of the Research

• The results showed that in mares with RFM, the mRNA expression of IL-1β in the endometrium and IL-6 in the allantochorion was significantly higher than in mares who had successfully expelled the placenta. The increased IL-6 protein expression in the allantochorion was consistent with the mRNA expression results.
• However, there were no visible changes in the TNFα mRNA and protein expression in mares with RFM compared to mares without the condition, with TNFα mRNA barely detectable.
• All the cytokines under study were confirmed to be present in the allantochorion through immunocytochemistry.

Conclusions and Future Directions

• The study suggests that the onset of inflammation, governed by certain proinflammatory cytokines, plays a role in the detachment and expulsion of the placenta in mares.
• The increased expression of IL-1β in the endometrium and IL-6 in the allantochorion may denote a local immune response that contributes to the detachment of fetal membranes.
• The low expression of TNFα may point towards its possible irrelevance in the expulsion process of fetal membranes.
• However, more research is needed to understand the exact role and timing of these cytokines during equine parturition.