Extracellular matrix proteases contribute to progression of pelvic organ prolapse in mice and humans
Madhusudhan Budatha, Shayzreen Roshanravan, Qian Zheng, Cecilia Weislander, Shelby L. Chapman, Elaine C. Davis, Barry Starcher, R. Ann Word, Hiromi Yanagisawa
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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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 3

Gelatin zymography using conditioned media from primary vaginal stromal cells.

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Gelatin zymography using conditioned media from primary vaginal stromal ...
(A) Conditioned media were harvested from WT cells after 24 hours of stimulation. Fibronectin (FN) did not alter gelatinolytic activity in WT cells. TNF-α was used as positive control for MMP-9 induction. (B) Fbln5–/– (KO) or Fbln5RGE/RGE (R) cells were incubated with FN, fibulin-5 (F5), or both simultaneously (FN+F5). Note a marked upregulation of MMP-9 after fibronectin stimulation in mutant cells. Whereas fibulin-5 alone showed no effects, fibulin-5 inhibited fibronectin-induced upregulation of proMMP-9. (C and D) Incubation with β1 integrin–blocking antibody or RGD peptides inhibited fibronectin-induced upregulation of MMP-9 in KO (C) and RGE (D) stromal cells. Experiments were performed 4 times using independent primary cell preparations. In B, the last 7 lanes were run on the same gel but were noncontiguous.