Alterations in T cell-related transcripts at the feto-maternal interface throughout equine gestation.

This research evaluates the balance between different types of T cells in pregnant horses throughout gestation with a focus on the feto-maternal interface. The goal is to understand how the immune response evolves over the course of pregnancy.

Research Context

• In humans, a delicate balance is maintained by the maternal immune system to both recognize and protect the fetus during pregnancy. This regulation is achieved by balancing different types of helper T cells (Th1, Th2) alongside immune suppression from a regulatory arm called Tregs.
• The same balancing act hasn’t been extensively studied in horses, though. That’s where this research steps in, examining the changes in key T cell-related transcripts at the feto-maternal interface—where the mother’s and fetus’s tissues meet—throughout equine gestation.

Methodology

• RNA sequencing was performed on two types of tissues—chorioallantois and endometrium—at various gestational stages: 120, 180, 300, and 330 days. Additionally, tissues from 45-day chorioallantois and diestrus (non-pregnant period) endometrium were also examined.
• The researchers were particularly interested in the transcripts relating to Th1, Th2, and Treg cells. Changes observed in the transcript levels were further confirmed using qPCR and immunohistochemistry.

Findings

• In the maternal endometrium, Th1-related transcripts were found to be most abundant in non-pregnant mares (diestrus) and decreased as pregnancy progressed.
• Conversely, Th2 transcripts began increasing right from the early stages of pregnancy and reached their peak during mid-gestation, indicating an up-regulation compared to non-pregnant mares.
• Treg-related transcripts also increased in number compared to non-pregnant mares, but declined as the mares neared their delivery date.
• In the fetal chorioallantois, Th1 transcripts showed no change while the majority of Th2 transcripts increased from 45 to 300 days of gestation but then declined as parturition approached.
• Treg-related transcripts initially decreased in the chorioallantois from 45 days to 120 days gestation, after which they got upregulated till 300 days, but then experienced a secondary decline just before parturition.

Conclusion

• The study reveals a complex, dynamic immune profile within the tissues of the feto-maternal interface in pregnant horses. This consists of a balance between Th1 and Th2 responses and a dynamic Treg response, which the researchers believe could be moderating the overall events within the immune system.
• Understanding these immune changes can pave the way for better reproductive health management in equines and potentially other animals as well.