| Summary: | Stress incontinence (SI) is more common in white women (61%) than in black African women (27%). Previous studies have demonstrated that collagen XVII is increased and the collagen I:III ratio is decreased in continent black women compared to white suggesting better adhesiveness and elasticity in the tissue of black women. We decided to examine this concept further and analyse the elastin content in paraurethral vaginal tissue of black and white women with or without stress incontinence. A further study was set up to examine if topical oestrogen could increase elastin and change associated components of white women with pelvic organ prolapse (POP). Oestrogen treatment has been shown to increase pro-mmp2 and new collagen formation in SI women, therefore it seemed possible that such treatment could affect the collagen and elastin components of POP favourably. The clinical symptoms of POP and surgical outcome may also be improved. The first study examined the elastin content by histochemistry in paraurethral vaginal tissue while the second study assessed how locally applied oestrogen (Vagifem) given over three months influenced the mRNA expression of MMP2, elastin and collagen XVII and also elastin, collagen I and collagen III protein content of vaginal skin from women with POP. In the racial comparison study black controls showed a highly significant increase in elastin content compared with white controls (p<0.01). For SI to occur in black women a severe insult that reduces elastin production appears to be necessary as black women with SI showed significantly lower elastin content compared with black controls (p<0.05). After application of topical oestrogen to white women with POP it was shown that mRNA for MMP2 is up-regulated (p<0.01) while that for ER alpha receptor is not (p=NS). The message for collagen XVII was down-regulated (p<0.01) while collagen I and III protein were increased significantly (p<0.001 in both cases). The mRNA for elastin was significantly increased (p<0.05) after treatment but the increase in elastin protein staining did not quite reach significance. In conclusion, black women have higher elastin content in vaginal tissue compared to white and this may contribute to the lower incidence of SI in black women. Topical oestrogen over a short period has remodelling effects on key factors of the extracellular matrix of vaginal tissue. Although significant rises in elastin mRNA were shown but not protein, this treatment over longer term application could enhance some of the changes seen. This research provides evidence that black women have beneficial characteristics of vaginal skin that could resist SI and POP. Oestrogen treatment with refinements for white women could mimic black characteristics and alleviate POP symptoms.
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