Steroidal regulation of uterine resistance to bacterial infection in livestock

Abstract

Postpartum uterine infections reduce reproductive efficiency and have significant animal welfare and economic consequences. Postpartum uterine infections are classified as nonspecific, but Arcanobacterium pyogenes and Escherichia coli are usually associated with them in cattle and sheep. Pyometra is the most common type of uterine infection in dairy cattle, and it is detected almost exclusively in cows with active corpora lutea. Luteal progesterone typically down-regulates uterine immune functions and prevents the uterus from resisting infections. Progesterone also can down-regulate uterine eicosanoid synthesis. This seems to be a critical event in the onset of uterine infections, because eicosanoids can up-regulate immune cell functions in vitro. In addition, exogenous prostaglandin F2 alpha stimulates uterine secretion of prostaglandin F2 alpha and enhances immune functions in vivo. Thus, one may hypothesize that eicosanoids can override the negative effects of progesterone and that the up-regulatory effects of exogenous prostaglandin F2 alpha allow the uterus to resolve an infection, regardless of progesterone concentrations. Based on the results of studies to test that hypothesis, cows, sheep, and pigs in various physiological statuses are resistant to intrauterine infusions of Arcanobacterium pyogenes and Escherichia coli, unless progesterone concentrations are increased. In sheep and pigs, exogenous prostaglandin F2 alpha stimulates uterine production of prostaglandin F2 alpha and allows the uterus to resolve Arcanobacterium pyogenes-Escherichia coli-induced infections, even when progesterone is maintained at luteal phase concentrations before and after treatment. Prostaglandin F2 alpha is a proinflammatory molecule that stimulates the production of various proinflammatory cytokines, and it may enhance uterine production of leukotriene B4. Proinflammatory cytokines and leukotriene B4 enhance phagocytosis and lymphocyte functions. Even though there are clear associations among prostaglandin F2 alpha, leukotriene B4, proinflammatory cytokines, phagocytosis, and lymphocyte functions, the mechanism of action of exogenous prostaglandin F2 alpha in overriding the down-regulatory effects of progesterone and resolving uterine infections has not been elucidated. Defining this mechanism should yield new prevention and treatment strategies for uterine infections that do not rely on antibiotic and antimicrobial compounds.

Breed-specific differences in the immune response to lipopolysaccharide in ewes

“…; Lutalyse, Pharmacia and UpJohn, New York, NY) at CIDR removal (Dixon et al, 2007). Estrous synchronization ensured similar hormonal stage of all ewes, as reproductive hormones are known to affect the inflammatory response (Lewis, 2003). On day 4 after estrus, ewes were weighed (without food or water restriction), sorted into pens in the barn, and given hay and water free choice.…”

Tolerance and Innate Immunity Shape the Development of Postpartum Uterine Disease and the Impact of Endometritis in Dairy Cattle

“…One consideration about the links between the uterus and ovary is that ovarian steroid hormones can also influence the development of postpartum uterine disease. Progesterone is immunosuppressive, whereas estradiol may enhance immunity and was used to treat uterine disease (147). However, there are conflicting data about how estradiol could increase uterine resistance.…”

Innate immunity and inflammation of the bovine female reproductive tract in health and disease

“…Presumably, this allows T. pyogenes and pyolysin to access the stromal compartment of the endometrium to establish infection and cause tissue damage. The duration and severity of clinical endometritis following infusion of bacteria can be increased by administering exogenous progesterone to the animal, or by infusion of bacteria during the luteal phase of the oestrous cycle (Rowson et al 1953, Lewis 2003. Similarly, early ovulation after parturition and establishment of a progesterone-dominated phase before pathogenic bacteria are eliminated predisposes to the development of pyometra (Olson et al 1984).…”

“…Similarly, early ovulation after parturition and establishment of a progesterone-dominated phase before pathogenic bacteria are eliminated predisposes to the development of pyometra (Olson et al 1984). Conversely, administering oestrogens or oestrus often precludes the establishment of uterine disease (Rowson et al 1953, Lewis 2003. However, the mechanisms linking the steroids to immunity are yet to be fully elucidated and are complex because there are interactions between the physiological effects of ovarian steroids and the inflammation caused by infusion of bacteria or LPS (Peter et al 1989, Karsch et al 2002, Lewis 2003.…”