Urinary incontinence is a major public health problem in the United States, resulting in an 11% lifetime risk of surgery for women with incontinence and/or prolapse. The basic molecular pathophysiology of urinary incontinence is poorly understood and, therefore, the development of medical prophylaxis or therapy for this growing area of disability for older women has lagged. The investigators hypothesize that stress urinary incontinence (SUI) results from abnormal pelvic collagen metabolism as a function of differential expression of the matrix metalloproteinases (MMPs) known to degrade extracellular matrix collagen and the tissue inhibitors of metalloproteinases (TIMPs) which specifically inhibit MMP proteolytic activity. Thus, variations in the expression of MMPs and TIMPs govern the amount and type of collagen in the supporting pelvic structures by controlling proteolysis. They propose to investigate MMP and TIMP expression in vaginal cuff tissue isolated from women with SUI and continent women before and after menopause to delineate differences in proteolytic activity and pelvic collagen content by, first, measuring mRNA and protein expression of MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 by quantitative, competitive reverse transcription polymerase chain reaction, Western blot analysis, and zymography. Second, they will culture tissue fibroblasts from vaginal cuff samples from control and incontinent women and determine the in vitro mRNA and protein expression of MMPs and TIMPs in response to gonadal steroid, cytokine, and growth factor modulation. Third, to confirm differences in collagenolysis between control and incontinent women, they will measure and compare total collagen content, ratio of type I/type III collagen, amount of the carboxy-terminal epitope, COL2-3/4Cshort, generated by the initial collagen cleavage, and level of pyridinoline crosslinks from both in vivo isolated vaginal cuff tissue and in vitro cultured fibroblasts from control and incontinent patients. Two-thirds of the burden of urinary incontinence is borne by women with prevalence rates of 14 to 41%. The investigators do not believe that any medical therapy for SUI is available. Their fourth goal is to determine the ability of a clinically relevant MMP inhibitor (RS113,456; Roche Bioscience, Inc.) to ablate in vivo MMP proteolysis in fibroblast cultures from women with SUI and control women. Such MMP inhibitors may offer a therapeutic intervention to reverse the pathophysiologc degradation of collagen in women as they age, which results in incontinence.
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