Inflammatory components in uterine fluid from mares with experimentally induced bacterial endometritis.

This research investigates how inflammatory substances in uterine fluid, in mares, change over time after a bacterial infection with Streptococcus zooepidemicus. The study found that protein concentrations and certain enzymes like lysozyme and lactate dehydrogenase increased over time, prostaglandin E2 concentrations appeared after infection, and neutrophils increased significantly within 30 minutes.

Methodology

• The researchers induced bacterial endometritis—an infection of the uterus—in healthy mares during oestrus via intrauterine infusions of Streptococcus zooepidemicus.
• They collected exudate (fluid) and uterine flushings at different time intervals 30, 60, 120, and 240 minutes after the infusions. They also collected flushings from uteri without prior induction of endometritis as a control group.

Findings

• The study found a time-dependent increase in protein concentrations in both the exudate and the flushings after the infection.
• The pH of the exudate decreased with time, even though the pH of the flushings remained stable. The change in pH can be a response to inflammation as the body attempts to prevent bacterial proliferation.
• Two enzymes, lysozyme and lactate dehydrogenase, were observed in the flushings from non-infected uteri, but their concentrations increased over time after infection. Lysozyme has antimicrobial properties, while lactate dehydrogenase is an enzyme that is often released in response to tissue damage or disease.
• The inflammatory substance called prostaglandin E2 was not detectable before infection, but concentrations rose after it. The presence of this substance typically signifies a bodily response to an infection or inflammation.
• No neutrophils—white blood cells that are part of the immune system’s response to infection—were present in the non-infected flushings. However, 30 minutes into the infection, researchers noted a significant increase of neutrophils in both exudate and flushings. Thereafter, the number of neutrophils continued to grow, especially in the exudate.

Conclusion

• The study concluded that acute endometritis in mares resembled acute inflammation at other sites in a horse’s body, as significant responses were recorded as early as 30 minutes after experimental infection.
• This reveals how the body’s defense mechanism rapidly responds to a bacterial infection, showing a concerted effort to fight off the pathogen.