[The early chemotactic reaction of the equine uterus to acute inflammatory stimulation].

The researchers observed how an infection in the uterus of pony mares in oestrus, specifically by the bacterium Streptococcus zooepidemicus, triggers a quick reaction from the immune system, especially from neutrophils. The findings show that the uterus starts to produce substances that attract neutrophils to the site of infection within 30 minutes, thus potentially explaining the immune system’s early response to acute endometritis in mares.

Experimental Design and Methodology

• The experiment began with infecting the uteri of normal pony mares in oestrus with Streptococcus zooepidemicus, a bacterium commonly associated with equine uterine infections.
• The uterine contents were collected at different intervals: 30, 60, 120, or 240 minutes after infection.
• These samples were then tested for their chemotactic effect — their ability to attract neutrophils, a type of white blood cell that plays a crucial role in the immune response — using two assays, one that measured neutrophil shape changes and another using a modified Boyden chamber technique to count and assess cell migration.

Findings of the Research

• Results revealed that as early as 30 minutes post-infection, the contents of the uterus had become markedly chemotactic for isolated peripheral neutrophils, meaning they were capable of attracting these immune cells to the site.
• This chemotactic properties remained up to the 240-minute mark.
• In comparison, the uterine contents from uninfected mares showed minimal chemotactic properties, suggesting that the infection-induced chemotaxis was a targeted immune response and not a random occurrence.

Conclusion and Implications

• This research could provide an explanation for the early influx of neutrophils observed during the onset of acute endometritis — an inflammatory condition of the uterine lining — in mares.
• It suggests that the rapid neutrophil response is likely due to the activation of an endogenous chemotactic system, a built-in signal the uterus sends out to attract the immune cells when there is a detection of a foreign entity, such as bacteria.
• Such findings can provide insights into treating or managing endometritis in mares, potentially through methods that could modulate this chemotactic response.