Bioscientifica Proceedings

Summary. Microbes commonly infect the female genital tract of cattle, causing uterine disease, abortion, and infertility. In particular, postpartum uterine disease develops in about 40% of dairy cows following infections with Gram-negative Escherichia coli and Gram-positive bacteria, such as Trueperella pyogenes. These infections damage tissues and cause inflammation in the endometrium, and perturb follicle growth and function in the ovary. Innate immunity is the first line of defence against microbes, and inflammatory responses depend on host cellular pattern recognition receptors detecting pathogen-associated molecular patterns. The Toll-like receptor (TLR) family are the most widely studied pattern recognition receptors, with TLR4 binding lipopolysaccharide from Gram-negative bacteria, whilst TLR2 in concert with TLR1 or TLR6 recognise bacterial lipopeptides. Innate immunity in the uterus is not only dependent on immune cells such as neutrophils and macrophages. Endometrial epithelial and stromal cells also express TLRs, and secrete cytokines, chemokines, and prostaglandins in response to lipopolysaccharide and bacterial lipopeptides. In addition, bacterial virulence factors such as pore-forming toxins contribute to the pathology in the endometrium by causing endometrial cytolysis. In the ovary, granulosa cells of antral follicles also possess TLRs and secrete inflammatory mediators in response to pathogen-associated molecular patterns. Furthermore, lipopolysaccharide inappropriately activates the earliest stage of follicle development, and perturbs the normal processes of oocyte maturation and early embryo development. In conclusion, endocrine cells of the bovine endometrium and ovary have roles in innate immunity and the defence against microbes, whilst cellular responses to the pathogen-associated molecular patterns disrupt the physiology of reproduction.

© 2014 Society for Reproduction and Fertility