Extracellular matrix proteases contribute to progression of pelvic organ prolapse in mice and humans
Madhusudhan Budatha, … , R. Ann Word, Hiromi Yanagisawa
Madhusudhan Budatha, … , R. Ann Word, Hiromi Yanagisawa
Published April 25, 2011
Citation Information: J Clin Invest. 2011;121(5):2048-2059. https://doi.org/10.1172/JCI45636.
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Research Article

Extracellular matrix proteases contribute to progression of pelvic organ prolapse in mice and humans

Abstract

Pelvic organ prolapse (POP) is a common condition affecting almost half of women over the age of 50. The molecular and cellular mechanisms underlying this condition, however, remain poorly understood. Here we have reported that fibulin-5, an integrin-binding matricellular protein that is essential for elastic fiber assembly, regulated the activity of MMP-9 to maintain integrity of the vaginal wall and prevented development of POP. In murine vaginal stromal cells, fibulin-5 inhibited the β1 integrin–dependent, fibronectin-mediated upregulation of MMP-9. Mice in which the integrin-binding motif was mutated to an integrin-disrupting motif (Fbln5RGE/RGE) exhibited upregulation of MMP-9 in vaginal tissues. In contrast to fibulin-5 knockouts (Fbln5–/–), Fbln5RGE/RGE mice were able to form intact elastic fibers and did not exhibit POP. However, treatment of mice with β-aminopropionitrile (BAPN), an inhibitor of matrix cross-linking enzymes, induced subclinical POP. Conversely, deletion of Mmp9 in Fbln5–/– mice significantly attenuated POP by increasing elastic fiber density and improving collagen fibrils. Vaginal tissue samples from pre- and postmenopausal women with POP also displayed significantly increased levels of MMP-9. These results suggest that POP is an acquired disorder of extracellular matrix and that therapies targeting matrix proteases may be successful for preventing or ameliorating POP in women.

Authors

Madhusudhan Budatha, Shayzreen Roshanravan, Qian Zheng, Cecilia Weislander, Shelby L. Chapman, Elaine C. Davis, Barry Starcher, R. Ann Word, Hiromi Yanagisawa

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Figure 6

Attenuation of prolapse phenotypes in Fbln5–/–;Mmp9–/– (DKO) mice.

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Attenuation of prolapse phenotypes in Fbln5–/–;Mmp9–/– (DKO) mice. (...
(A) Postnatal analysis of MMP-9 levels in WT and Fbln5–/– (KO) vaginas. Vaginas were harvested at indicated day and subjected to gelatin zymography. Note an increase in MMP-9 activity in the mutants at 24 days of age but not in WT. PC, adult KO vagina serves as a positive control. In WT gel, first 11 lanes were run on the same gel but were not contiguous. (B) Prolapse development in Fbln5+/+ (n = 16–23, white circles), Fbln5–/–;Mmp9+/+ (n = 25–36, black triangles), Fbln5–/–;Mmp9+/– (n = 39–42, black squares), and DKO (n = 18–25, black circles) from 6–46 weeks. Data represent percentage of animals developing overt prolapse (≥ stage 2). Although prolapse was assessed weekly, for simplicity, data are presented at 4-week intervals. *P < 0.01 compared with Fbln5–/–;Mmp9+/+ or Fbln5–/–;Mmp9+/–, log-rank survival analysis. (C) Representative images of KO (left) and DKO (right) littermates at 33 weeks. Note rescue of urogenital bulge (arrow) and anal prolapse (a) in DKO. (D) Representative Hart’s staining (upper panels) of transverse sections of the mid-vagina from KO (n = 6) or DKO (n = 6) mice at 1 year of age. A marked increase in elastic fiber density is observed in the subepithelial stroma of DKO mice. Pentachrome staining (lower panels) of the vagina from KO (n = 3) or DKO (n = 3) mice at 1 year old. Note collagen fibrils were thicker and continuous in DKO mice compared with Fbln5–/– mice (insets). Scale bars: 20 μm. (E) Quantification of elastic fiber density. (F) Collagen area fraction. Each symbol represents mean determination from a single animal. Data are represented as mean ± SEM. *P < 0.05.