Serum amyloid A, Serum Amyloid A1 and Haptoglobin in pregnant mares and their fetuses after experimental induction of placentitis.

The research examines the levels of serum amyloid A (SAA), SAA1, and Haptoglobin (Hp) in pregnant horses and their fetuses after the intentional induction of placentitis, an inflammatory condition. The study found that concentrations of these inflammatory proteins were generally higher in mares with induced placentitis, particularly in specific maternal and fetal tissues.

About the Study and Proteins

• This study set out to understand the behavior of serum amyloid A (SAA), serum amyloid A1 (SAA1), and haptoglobin (Hp) under conditions of inflammation, particularly placentitis, an inflammation of the placenta.
• SAA, SAA1, and Hp are known as acute phase proteins. These are proteins whose plasma concentrations increase or decrease significantly in response to inflammation.
• In horses, SAA and SAA1 are protein coding genes that produce these acute phase proteins.

Study Design and Execution

• The researchers attempted to induce placentitis in pregnant mares to explore how this would affect the concentrations and relative abundance of these proteins and their mRNA transcripts both in the mother and fetus.
• The control group included healthy mares that had not been experimentally exposed to placentitis.

Results and Findings

• The study observed a marked increase in the presence of SAA family proteins in the stroma of the endometrium and chorioallantois, tissues associated with inflammatory cells in the test group with induced placentitis.
• The maternal plasma SAA concentrations were greater in mares with induced placentitis compared to the control group.
• Maternal haptoglobin concentrations remained the same across both groups but higher fetal Hp concentrations were seen in the test group mares with induced placentitis.
• Mothers with induced placentitis had greater SAA and Hp concentrations than their fetuses.
• The relative abundance of SAA mRNA transcript was greater in the maternal, fetal liver, and chorioallantois of the test group mares compared to the control.
• Interestingly, the relative abundance of the SAA1 mRNA transcript was only higher in the chorioallantois of mares with induced placentitis.

Conclusion and Future Directions

• Overall, the SAA and Hp concentrations proved to be greater in mares with induced placentitis, suggesting that these proteins play a significant role in the inflammatory response related to placentitis.
• The intriguing finding about the more significant abundance of the SAA1 mRNA transcript specifically in the chorioallantois of the mares with induced placentitis suggests that there is some unique immunological response occurring in this tissue, which warrants further investigation.