Changes in biological characteristics during the cellular aging of ligament fibroblasts derived from patients with prolapsus uteri

Potential molecular targets for intervention in pelvic organ prolapse

Pelvic organ prolapse (POP) is a concerning gynecological benign illness in middle-aged and senior women. Its etiology is complex, the incidence rate is high, symptoms are clinically subjective, and its influence tends to be polarized. At present, for those who need medical treatment, whether surgical or non-surgical, complications cannot be ignored, and treatment effect needs to be optimized. However, there is a lack of accurate molecular biological interventions for the prevention, diagnosis, progression delay, and treatment of POP. Here, we reviewed the current state of understanding of the molecular mechanisms and factors associated with POP etiology. These factors include cyclins, matrix metal peptidases/tissue inhibitors of metalloproteinases, microRNAs, homeobox A11, transforming growth factor β1, insulin-like growth factor 1, fibulin 5, lysyl oxidase-like 1, oxidative stress, inflammatory response, estrogen, and other potential biomarkers associated with POP. In addition, relevant molecular targets that may be used to intervene in POP are summarized. The aim of this review was to provide more information to identify accurate potential biomarkers and/or molecular targets for the prevention, diagnosis, progression delay, and treatment of POP, with the goal of improving medical treatment for patients at-risk for POP or having POP. Continued research is needed to identify additional details of currently accepted molecular mechanisms and to identify additional mechanisms that contribute to POP.

Correlation Between Autophagy and Collagen Deposition in Patients With Pelvic Organ Prolapse

OBJECTIVES

The aim of this study was to explore the link between autophagy and collagen metabolism in patients with pelvic organ prolapse (POP) by detecting the expressions of autophagy factors, collagen, desmin, cytokeratin, and vimentin.

METHODS

Histology of anterior vaginal wall and uterosacral ligament was assessed by hematoxylin-eosin staining in POP and non-POP control patients (n = 50 per group). Expressions of collagen types I and III, LC3II, beclin 1, and p62 were examined by Western blot analysis. Expressions of LC3, vimentin, desmin, and cytokeratin were detected by immunohistochemical staining. A linkage between the mean of LC3 integrated option density summation (IOD SUM) and POP clinicopathologic parameters including Pelvic Organ Prolapse Quantification (POP-Q) staging, age, body mass index, gravidity, and parity was analyzed by χ test, respectively.

RESULTS

Compared with the control group, the following differences were found both in the vaginal wall and in the uterosacral ligament of the POP group: hematoxylin-eosin staining showed that collagen was more fragmented and disorganized. Expressions of collagen types I and III, LC3II, and beclin 1 were diminished, whereas the p62 level was elevated in Western blotting. Immunohistochemical staining showed that expression of LC3 was down-regulated, whereas vimentin level was increased. There were no significant differences in the expressions of desmin and cytokeratin in the 2 groups (P > 0.05). Mean of LC3 IOD SUM was highly linked to the POP-Q stage in the POP group (P < 0.05), whereas there was no significant correlation between the mean of LC3 IOD SUM and POP groups in age, body mass index, gravidity, and parity, respectively(P > 0.05).

CONCLUSIONS

Autophagic activity is impaired in the POP group, which may relate to collagen deposition.

Proliferative behavior of vaginal fibroblasts from women with pelvic organ prolapse

OBJECTIVE

Pelvic organ prolapse (POP) significantly impacts quality of life of women, especially with advancing age. Cell proliferation is a critical parameter in both normal and pathophysiological processes. We sought to examine fibroblast proliferation in premenopausal women with and without POP and menopausal women with POP, and examine whether TGF-β1, a fibroblast mitogen, could stimulate proliferation in vaginal fibroblasts from these populations.

STUDY DESIGN

Vaginal wall biopsies were obtained from asymptomatic women (controls) and women with POP (cases). Fibroblasts were cultured from these tissues. Vaginal fibroblasts were treated with or without TGF-β1. Cell proliferation rate (mitotic index) was measured with time-lapse dark-field microscopy. Cell mitosis was counted with ImageJ software after analysis of time-lapse images as Quick time movies.

RESULTS

There was no significant difference in mitotic index throughout different time points of observation between premenopausal controls and cases of similar ages. However, a significant difference in mitotic index was seen between premenopausal and menopausal cases (p=0.01), with the menopausal group exhibiting significantly lower mitotic indices. When treated with different doses of TGF-β1, premenopausal control fibroblast proliferation increased with 5ng/ml of TGF-β1 compared to non-treated fibroblasts (p=0.04). TGF-β1 stimulation did not affect fibroblasts from either premenopausal or menopausal cases.

CONCLUSIONS

Vaginal fibroblast proliferation decreases with age and this association does not appear to be affected by the presence of pelvic organ prolapse. TGF-β1 stimulation increased cell proliferation of premenopausal control fibroblasts. In contrast, there was no response seen in fibroblasts from premenopausal and menopausal cases.

Changes of glycoprotein and collagen immunolocalization in the uterine artery wall of postmenopausal women with and without pelvic organ prolapse

Pelvic organ prolapse (POP) is accompanied by an altered composition of the extracellular matrix (ECM). However, it is unclear whether the changed ECM is the cause or the consequence of POP, as stretching of the tissue may have an effect on the composition of the ECM. To address this question, we analyzed the connective tissues of the uterine artery wall of postmenopausal women with and without POP. The uterine artery wall is stretched in patients with POP, but this stretching is unlikely to cause the POP. Twenty-one women (13 with POP and 8 without POP) hospitalized for hysterectomy were included in this study. Tissue samples from the uterine artery were analyzed for collagen (types I, III, IV, V and VI) and other ECM proteins (fibronectin, laminin, tenascin, vitronectin and elastin) using immunofluorescence microscopy. Results revealed that uterine artery samples of women with prolapse showed a significantly weaker immunoreactivity to type VI collagen, vitronectin and elastin and a stronger immunostaining for type III collagen and tenascin as compared to control samples. Our results suggest that the ECM may be altered in response to mechanical stretch. Changes in the ECM composition as observed in POP may not necessarily be the reason for the development of pelvic floor relaxation in postmenopausal women.

Differential elastin and tenascin immunolabeling in the uterosacral ligaments in postmenopausal women with and without pelvic organ prolapse

Connective tissue, consisting mainly of collagen and structural glycoproteins, is an important part of the supportive structures of the genitourinary region. Relatively few data have been published with respect to the role of elastin and glycoproteins in pelvic organ prolapse (POP). Connective tissue of the uterosacral ligament in postmenopausal women with and without genital prolapse was compared. Fifty-nine consecutive women referred for hysterectomy were included in the study. The patients had POP or benign gynecological disease (e.g. myoma of the uterus). Tissue samples from the uterosacral ligament were investigated for localization and distribution of tenascin and elastin using immunofluorescence microscopy. Tissue samples of women with prolapse showed a significantly (p<0.001) weaker immunofluorescent labeling of tenascin compared to samples taken from women without prolapse. Tenascin was detectable in tissues of all women with POP, whereas its immunolabeling was decreased in the uterosacral ligament in women without POP. Intact elastin fibers were observed in tissues of all women without POP, whereas elastin was undetectable or sometimes fragmented in the uterosacral ligament in women with POP. Greater amounts of tenascin and lesser amounts of elastin were therefore found in patients with POP. These results suggest that an altered turnover of connective tissue in the uterosacral ligament might be responsible for the presence of pelvic floor relaxation in postmenopausal women. These data indicate a complex architecture of the extracellular matrix in the uterosacral ligaments, with marked differences in tenascin and elastin expression between postmenopausal women with or without POP.

Increased expression of matrix metalloproteinase 2 in uterosacral ligaments is associated with pelvic organ prolapse

The uterosacral ligaments are an important part of the pelvic support system and connective tissue alterations are thought to contribute to the development of pelvic organ prolapse (POP). The objective of this study was to compare the expression of matrix metalloproteinases (MMPs) 1 and 2 in these ligaments in women with and without POP. We analyzed the tissue samples obtained from left and/or right uterosacral ligaments of 17 women with POP and 18 controls by immunohistochemistry. There was no difference in MMP-1 expression between women with POP and those without. In contrast, the MMP-2 expression was significantly related to the presence of POP (p=0.004) rather than to age or parity. There was no difference in MMP-1 and MMP-2 expression between left and right uterosacral ligaments in women with POP compared to controls. Our findings strongly indicate that increased MMP-2 expression in uterosacral ligaments is associated with POP.

Uterosacral ligament in postmenopausal women with or without pelvic organ prolapse

The uterosacral ligaments are thought to contribute to pelvic support. The objective of this study was to compare the structural components of these ligaments in women with and without pelvic organ prolapse (POP). We characterized uterosacral ligaments of 25 postmenopausal women with POP and 16 controls histomorphologically and immunohistochemically by quantifying their content of collagen I, III, and smooth muscle using a computerized image analysis. In 84% the uterosacral ligaments were composed of more than 20% of smooth muscle cells. There was no difference in collagen I expression and smooth muscle cell amount between women with POP and those without. In contrast, the collagen III expression was significantly related to the presence of POP (p<0.001) rather than age or parity. Our findings suggest that the higher collagen III expression might be a typical characteristic of POP patients' connective tissue. The considerable amount of smooth muscle cells in uterosacral ligaments may provide pelvic support.