The effects of Arcanobacterium pyogenes on endometrial function in vitro, and on uterine and ovarian function in vivo

Abstract

Uterine bacterial infection after parturition causes endometritis, perturbs ovarian function and leads to infertility in cattle. Although endometritis is caused by mixed infections, endometrial pathology is associated with the presence of Arcanobacterium pyogenes. The aims of the present study were to determine the effects of A. pyogenes on endometrial function in vitro, and on uterine and ovarian function in vivo. Heat-killed A. pyogenes did not affect the production of prostaglandin F2alpha (PGF) or prostaglandin E(2) (PGE) from endometrial explants, or purified populations of endometrial epithelial or stromal cells. However, the explants produced more PGF and PGE than controls when treated with a bacteria-free filtrate (BFF) cultured from A. pyogenes. Similarly, BFF stimulated PGF and PGE production by epithelial and stromal cells, respectively. So, BFF or control PBS was infused into the uterus of heifers (n=7 per group) for 8 days, starting the day after estrus. Emergence of the follicle wave, dominant follicle or corpus luteum diameter, and peripheral plasma FSH, LH, estradiol, progesterone, PGFM, or acute phase protein concentrations were unaffected by the BFF infusion. In the live animal it is likely that the intact uterine mucosa limits the exposure of the endometrial cells to the exotoxin of A. pyogenes, whereas the cells are readily exposed to the toxin in vitro.

Figure 1

The mean + SEM production of prostaglandin F₂ by endometrial (a) explants, and (b) epithelial cells treated with heat killed A. pyogenes (HKAP) at the concentrations indicated for 24 h.

Figure 2

The mean + SEM production of (a) prostaglandin F_2α and (b) prostaglandin E₂, by tissue explants treated for 24 h with BFF at the concentrations indicated or 1 μg/mL E. coli LPS. Values differ significantly from control ***P < 0.01, **P < 0.05

Figure 3

The mean + SEM production of (a) prostaglandin F₂ by endometrial epithelial cells, and (b) prostaglandin E₂ by stromal cells treated with BFF at the concentrations indicated or 1 μg/mL E. coli LPS. Values differ significantly from control ***P < 0.01, *P < 0.05

Figure 4

The mean ± SEM (a) diameter of the dominant follicle and peripheral plasma concentrations of (b) estradiol, (c) FSH, and (d) progesterone, for of 7 heifers infused with control PBS (■) or BFF (●) for 8 days.

Figure 5

Representative peripheral plasma LH concentration profiles after PG₂ and PG₃ for animals that were infused with (a) control PBS, or (b) BFF.