Fetal-fluid proteome analyses in late-term healthy pregnant mares and in mares with experimentally induced ascending placentitis.

The study set out to analyze and compare the different proteins found in the amniotic and allantoic fluids of healthy pregnant mares and those with experimentally induced placentitis.

Objective and Methodology

• The research aimed to understand the different proteins found in the fluids surrounding the fetus – the amniotic and allantoic fluids – in healthy conditions versus disease states, specifically placentitis, an inflammation of the placenta.
• Pregnant mares in good health were the subjects of the study. They were induced with placentitis by introducing Streptococcus equi ssp, a bacteria that causes diseases in horses, through their cervix.
• Both before and after the disease induction, samples of their allantoic fluid were collected using a procedure called centesis, a puncture into a body cavity to remove fluid. These were then analyzed along with the amniotic fluids collected after the horses were euthanized.
• Using a process called in-gel digestion, these fluids were analyzed through a high-throughput proteomic technique to determine their protein composition.
• All data was normalized for accurate statistical comparisons.

Findings

• 112 unique proteins were present in both amniotic and allantoic fluids. An additional 26 proteins were found in both types of fluids but there were 13 and 29 proteins unique to each type.
• The proteins found in the fetal fluids were functionally classified into multiple categories such as transfer carriers, enzymes, signaling molecules, and immunity-related proteins, among others. This provides valuable information about how these fluids contribute to the functioning, growth, and protection of the fetus.
• Placentitis caused by the introduced bacteria saw changes in the protein composition – 10 proteins were upregulated and 10 were downregulated in allantoic fluid. This indicates that the disease state altered the normal protein production and presence in the allantoic fluid.
• The changes in the proteome offer insights into how pregnancy functions in a healthy state and how diseases like placentitis can disrupt this functioning, making it potentially useful for the future development of diagnostics or treatments for related conditions in horses.