Gene profiling of inflammatory genes in day 18 endometria from pregnant and non-pregnant mares.

This study investigates the processes within a horse’s uterine lining (endometrium) around day 18 of pregnancy to better understand how the body recognizes and supports the early stages of pregnancy. The research shows that early equine pregnancy impacts the gene expression within the endometrium, particularly those genes involved with inflammation and cell growth.

Research Methodology

• The researchers’ methodology involved inseminating mares and obtaining endometrial biopsies from pregnant mares on Day 18 post-ovulation.
• For control purposes, during subsequent estrous cycles, mares were not inseminated and Day 18 post-ovulation endometrial biopsies were also taken.
• They used an Affymetrix equine GeneChip (microarray technology) to track gene expression profiles. This chip was specially designed with probes that screen for genes linked to inflammation processes.

Major Findings

• Analysis showed that 118 genes were more active (up-regulated), while 93 genes were less active (down-regulated) in the endometrium of pregnant mares when compared to non-pregnant mares.
• The changes were significant, with at least a 1.5-fold difference in activity.
• The team confirmed these results using quantitative, real-time RT-PCR for a few select genes.
• Increased expression was seen for genes TSC22D3, PPAPDC2, and KLF6 that have homologous function in humans, while the expression of genes ESR1, MARCKSL1, and EPSTI1 with homologous function in humans was decreased.

Conclusions

• The different gene expression observed around Day 18 in pregnant mares, the researchers concluded, likely reflects an anti-inflammatory reaction that reduces the production of a particular hormone (prostaglandin F(2α)) that could cause the termination of pregnancy by letting the corpus luteum (a temporary structure that is crucial in maintaining pregnancy) die off.
• This implies that the presence of an embryo in the equine uterus triggers gene activity adjustments within the endometrium.
• The genes with changed expression are related to inflammation processes and pathways involving cellular growth and proliferation, suggesting their potential role in maternal recognition or support of early pregnancy.
• These findings provide important insights into the body’s genetic responses during the early stages of equine pregnancy and may contribute to the understanding of pregnancy in other species, possibly including humans.