Perturbed sperm-epithelial interaction in bitches with mating-induced endometritis

Area of Science:

• Veterinary Medicine
• Reproductive Biology
• Immunology

Background:

• A transient uterine inflammatory response post-mating aids in clearing contaminants.
• In some individuals, this response can become excessive, leading to mating-induced endometritis and infertility.

Purpose of the Study:

• To investigate the influx of polymorphonuclear neutrophils (PMNs) into the uterine lumen of bitches after artificial insemination.
• To understand the relationship between endometrial hyperplasia, mating-induced endometritis, and fertility in bitches.

Main Methods:

• Artificial insemination with fresh semen in bitches.
• Quantification of PMN influx into the uterine lumen.
• Assessment of pregnancy rates and litter size.
• In vitro co-culture studies to evaluate spermatozoal attachment to uterine epithelium.

Main Results:

• Normal bitches showed a physiological PMN influx, high pregnancy rates, and normal litter size.
• Bitches with endometrial hyperplasia exhibited a larger PMN influx, reduced pregnancy rates, and smaller litter sizes.
• Antibiotic treatment partially ameliorated the negative effects in bitches with hyperplasia.
• In vitro studies revealed reduced spermatozoal attachment to hyperplastic uterine epithelium, further inhibited by PMNs.

Conclusions:

• Endometrial hyperplasia in bitches can lead to adverse reproductive outcomes due to mating-induced endometritis.
• Decreased spermatozoal attachment to uterine epithelium, exacerbated by PMNs, is a key factor mediating reduced fertility.
• This study highlights the physiological role of uterine inflammation and its pathological implications in canine reproductive diseases.