Unraveling the uterine fluid proteome of mares diagnosed with post-breeding and infectious endometritis.

Research Overview

• This study investigates the protein composition of uterine fluid in healthy mares compared to those diagnosed with infectious and post-breeding endometritis to better understand the disease mechanisms and identify potential diagnostic biomarkers.

Background

• Endometritis is the leading cause of subfertility in mares, causing significant challenges in equine reproduction.
• The uterine fluid contains proteins that may reflect the health status of the endometrium and could provide clues about endometritis development.
• Understanding the uterine fluid proteome could improve knowledge of disease etiology, diagnosis, and treatment strategies.

Study Design and Methods

• Subjects: Mangalarga Marchador breed mares in Muriaé, Brazil.
• Groups: Divided into three groups (n=8 per group) — healthy control, infectious endometritis, and post-breeding endometritis.
• Sample Collection: Uterine fluid collected using a low-volume lavage technique.
• Proteomic Analysis: Identified proteins using proteomic techniques and measured their relative abundance across groups.

Key Findings

• A total of 549 proteins were detected in the uterine fluid samples.
• 279 proteins were common across all three groups.
• Healthy mares:
  • Thirteen proteins predominantly expressed, associated with endometrial remodeling and early embryonic development.
  • Albumin and uteroglobin had higher abundance in healthy mares and those with infectious endometritis.
• Infectious endometritis group:
  • Enrichment of proteins linked to innate immune and inflammatory responses, including annexin and glutathione S-transferase.
  • Higher abundance of lipocalins, proteins involved in immune defense and inflammation regulation.
• Post-breeding endometritis group:
  • Fifty-five proteins identified that related to innate immune response signaling pathways and biological processes.
  • Notably high abundance of polymeric immunoglobulin receptor (PIGR) proteins, which facilitate the transport of IgA antibodies to the endometrial mucosa to help immune defense.

Conclusions and Implications

• The study reveals distinct protein profiles in uterine fluid corresponding to health status and type of endometritis in mares.
• Different sets of proteins are linked to infectious versus post-breeding inflammatory processes.
• These molecular alterations provide insights into how endometritis develops and progresses.
• Identified proteins have potential as biomarkers for improved diagnosis and treatment monitoring in equine reproductive health.
• Overall, this proteomic profiling advances understanding of uterine environment changes during health and disease, supporting better reproductive management in mares.