Aim: to study a correlation between clinical stage of pelvic organ prolapse (POP), a histological structure and results of immunohistochemical study of the vaginal wall were evaluated.
Materials and methods: A total of 60 peri- and postmenopausal women (average age 61.9+/-8.4 years) with POP of stage II-IV, according to the POP-Q classification, or with stress urinary incontinence and cystocele of stage I-II, who undergone to surgical treatment, were included in the study. During a procedure, a biopsy from the anterior vaginal wall was taken. Depending on the stage of POP, patients was divided into two groups. In the group 1, 30 patients with stage I and II of POP were included, while group 2 included 30 women with POP of stage III and more. The control group (group 3) consisted of 20 patients without POP (mean age 63.4+/-11.0 years) who underwent a hysterectomy due to to other indications. A histological and immunohistochemical studies of vaginal wall tissue was performed in order to determine the tissue content of collagen type I and III; matrix metalloproteinases 1 and 2 (MMP-1 and MMP-2), a tissue inhibitor of metalloproteinases 1 (TIMP-1), vimentin and smooth muscle actin.
Results: In contrast to two other groups, in group 2 there were significant changes in the connective tissue. Collagen has a form of fibrous mass with areas of reduced content. In addition, scarring areas with an increase in the content of type III collagen, a decrease in the amount of type I collagen and elastic fibers with significant fragmentation, were seen. Moreover, in patients with severe POP (III-IV), degradation of collagen fibers with a decrease in connective tissue strength and elasticity was detected. Women with POP had a low ratio of type I:III collagen. Analysis of the collagen content in the vaginal wall in patients with mild POP (I-II) revealed a significant increase in the level of collagen type I (p=0.0003) and a decrease in the content of type III (p=0.045), compared to patients with more severe POP (III-IV). The level of MMP-1 and MMP-2 in women with POP was higher, than in control group by 1.7 times (p<0.05). The content of TIMP-1 in the group 1 was significantly lower by 1.5 and 2.2 times, compared to group 2 and 3, respectively. An analysis of MMP-1 and MMP-2 concentration in patients of groups 1 and 2 revealed a significant (p=0.04) decrease in their activity in severe POP (III-IV). In women of the group 2, biopsy of the vaginal wall showed that expression of vimentin and smooth muscle actin in the connective tissue was significantly higher, than in group 1 and 3 (p<0.05). Vimentin expression in the group 2 was 1.4 and 2.6 times higher than in the group 1 and 3, respectively. In the control group, the expression of these markers in the vaginal wall was minimal and focal.
Conclusion: Our data indicate that fibrosis and degradation of the connective tissue in the vaginal wall predominate in POP, and these changes are a consequence, but not a cause of PG. The aggravation of degenerative changes in the connective tissue leads to the progression of POP.
Keywords: collagen; epithelial-mesenchymal transition; metalloproteinase; pelvic organ prolapse; vimentin and smooth muscle actin.