Estrogen Affects the Glycosaminoglycan Layer of the Murine Bladder

Abstract

Objectives Urinary tract infections (UTIs), commonly caused by uropathogenic Escherichia coli (UPEC), confer significant morbidity among postmenopausal women. Glycosaminoglycans (GAGs) comprise the first line of defense at the bladder’s luminal surface. Our objective was to use a murine model of menopause to determine whether estrogen status affects the GAG layer in response to UPEC infection. Methods Adult female mice underwent sham surgery (SHAM, n = 18) or oophorectomy (OVX, n = 66) to establish a murine model of menopause. A subset of oophorectomized mice underwent hormone therapy (HT, n = 33) with 17β-estradiol. Mice were inoculated with UPEC and killed at various time points; bladders were collected and GAG layer thickness was assessed in multiple bladder sections. Sixteen measurements were made per bladder. A repeated-measures 2-way analysis of variance was performed to determine the effect of time after infection and hormonal condition on GAG thickness. We also investigated the molecular underpinnings of GAG biosynthesis in response to alterations in estrogen status and infection. Results We did not observe significant difference of GAG thickness among the 3 hormonal conditions; however, the time course of GAG thickness was significantly different (P <0.05). The OVX mice demonstrated significantly greater thickness at 72 hours after infection (P = 0.0001), and this effect was shifted earlier (24 hours after infection) on the addition of HT (P = 0.001). At 2 to 4 weeks after infection, GAG thickness among all cohorts was not significantly different from baseline. In addition, quantitative reverse transcription–polymerase chain reaction analysis revealed that GAG biosynthesis is altered by estrogen status at basal level and on infection. Conclusions The GAG layer is dynamically altered during the course of UTI. Our data show that HT positively regulates GAG layer thickness over time, as well as the composition of the GAGs. In addition, the GAG sulfation status can be influenced by estrogen levels in response to UPEC infection. The protective effects of the GAG layer in UTI may represent pharmacologic targets for the treatment and prevention of post-menopausal UTI.

Estrogenic Modulation of Uropathogenic Escherichia coli Infection Pathogenesis in a Murine Menopause Model

“…We have previously shown that levels of a GAG-sulfating enzyme, HS6ST1, a key modulator of Bmp4 signaling, are increased upon infection (49). Additionally, we have shown that estrogen plays a key role in influencing the GAG thickness and the increased expression of GAG sulfation enzymes over the course of UPEC infection (29). Together, this leads us to speculate that increased sulfation of GAGs may modulate the downregulation of Bmp4 signaling and thereby the USC niche response to infection.…”

“…Seven-to 8-week-old C57BL/6 female mice (NCI Mouse Repository, Frederick, MD) were anesthetized and the ovaries excised as described previously (29). For sham surgery, the same procedures were performed without removal of the ovaries.…”

Mucoadhesive polyacrylamide nanogel as a potential hydrophobic drug carrier for intravesical bladder cancer therapy

“…8a2, the yz cross-section image at a higher magnification shows the thickness of the fluorescent nanogel-covered layer. This thickness approximately corresponds to the GAG layer on the urothelium surface, which has been reported to the 30-50 lm in the thickness (Anand et al, 2012;Birder and Andersson, 2013). In addition, quantification of fluorescence intensity was also carried out by integrating the intensity throughout the whole volume scanned by CLSM at a fixed magnification for a fixed area of 1.62 Â 10 6 lm 2 .…”

Recurrent urinary tract infections in healthy and nonpregnant women

“…Furthermore, in murine models, decreases in estrogen have been found to be related to delayed development of the protective bladder glycosaminoglycan layer, increasing susceptibility to bacterial colonization and IBC formation. 49 Postmenopausal women aged ≥ 70 years face unique challenges with regard to RUTI due to institutionalization and decreased functional status. Increased rates of catheterization, incontinence, and prolapse surgery lead to a substantial increase in risk of RUTI in this specific population.…”