Figure 1.

Schematic of mouse infection protocol and characteristics of infection. (A) In our laboratory, mice are treated with 17β-estradiol to promote Gc infection by implantation of a slow-release pellet under their skin (Jerse, 1999; not shown) or subcutaneous administration of water-soluble estradiol (estradiol_ws; 0.5 mg) on days −2, 0, and 2 (Song et al., 2008). The benefit of using estradiol_ws is that serum estradiol concentrations return to physiological levels within 24 h after administration, and in our treatment protocol, Gc is not exposed to abnormal levels by day 3 of infection as shown. The dotted line corresponds to estradiol levels in normal proestrus stage mice (Dalal et al., 2001) Mice are inoculated with bacteria on day 0. Not shown is the antibiotic treatment regimen, which has been adjusted over time due to changes in breeders and husbandry practices. Currently, streptomycin sulfate (Sm; 2.4 mg) and vancomycin hydrochloride (0.4 mg) are administered via intraperitoneal (i.p.) inoculation twice daily until day 2 of the infection period. Drinking water with trimethoprim sulfate (0.04 g/100 ml water) is used over the course of the experiment, with Sm (0.5 g/100 ml water) added on day 2 of the infection period. (B) An example of the average number of CFU recovered from a single vaginal swab suspended in 100 μl of PBS (left axis) and percent of PMNs in stained vaginal smears (right axis) is shown. Mice (n = 6) in this experiment were inoculated with 10⁶ CFU of strain FA1090. In published (Packiam et al., 2010) and unpublished data from our laboratory, increased levels of proinflammatory cytokines and chemokines are detected on day 5 of infection as shown, which corresponds to the influx of PMNs in infected mice. Asterisks denote time points at which the percentage of PMNs in infected mice (dashed lines, solid squares) was significantly higher than that in mice given PBS (dashed lines, open squares). Increased PMNs were observed in control mice on days 9 and 10, which is due to the effects of the estradiol wearing off and the resumption of the estrous cycle. Mice were colonized for an average of 9.9 days in this 12-day experiment. This figure was constructed with combined data reported in (Song et al., 2008; Packiam et al., 2010).