Immunology and Immunomodulation of the Reproductive Tract

Introduction
Persistent endometritis is a major cause of reproductive wastage and hence economic loss to the equine breeding industry. The endometrium of the mare is periodically exposed to numerous irritants and potentially infectious agents during breeding, iatrogenically during veterinary procedures, and when normal defense mechanisms become incompetent.

Multiple physical and functional barriers exist to prevent or minimize contamination between episodes of breeding and during pregnancy. Once introduced to the endometrium infectious agents encounter both innate and adaptive immune defenses consisting of both cellular and humoral factors. Components include the epithelial mucus barrier, resident innate immune cells, and their proinflammatory secretions that minimize the risk of infection. Acting in concert with the innate immune system, the adaptive immune system includes both cell-mediated and humoral responses generated towards specific pathogens. Cells of the innate and adaptive immune systems are influenced by the ovarian sex hormones, local growth factors, and the commensal genital tract flora. Much of what is known has been determined from laboratory species, humans and production animals. In the current review, this will be extrapolated to the horse where applicable. […]