Mechanisms of Infection and Immunity in the Bovine Female Genital Tract Post Partum

Abstract

Infection of the female genital tract with bacteria after parturition is common in cattle and in humans. These infections lead to clinical diseases, known as puerperal fever or pelvic inflammatory disease in humans but often called metritis or endometritis in cattle. In cattle, metritis affects 20-40% of animals during the first few weeks after parturition. Clinical endometritis persists in about 20% of animals beyond three weeks postpartum and subclinical endometritis affects many other animals. Clinical disease is characterized by the presence of pus, usually detected in the vagina, and associated with infection of the uterus by Escherichia coli, Arcanobacterium pyogenes and anaerobic bacteria. The inflammatory response to infection is dependent on sensing of the microbes by innate immune receptors on endometrial epithelial and stromal cells, which drives an influx of neutrophils to clear the bacteria. However, the innate immune response also perturbs the endocrine function of the endometrium, at least in part by switching prostaglandin secretion from the F to the E series. In addition, cows with uterine disease have abnormal estrous cycles, associated with modulation of ovarian follicle and corpus luteum function. In summary, postpartum bacterial infections are common in dairy cattle and clinical uterine disease disrupts normal fertility by affecting not only endometrial function but also ovarian health. [...]