Expression of matrix metalloproteinase-1 in round ligament and uterosacral ligament tissue from women with pelvic organ prolapse

The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis

BACKGROUND

Studies on the changes of extracellular matrix (ECM) in pelvic organ prolapse (POP) are still controversial.

OBJECTIVE

To identify the changes in the ECM in POP patients.

SEARCH STRATEGY

Comprehensive searching in Embase, PubMed, Web of Science and the Cochrane Library was carried out until 23 February 2023.

SELECTION CRITERIA

Studies comparing the protein levels of ECM-related components between women with and without POP.

DATA COLLECTION AND ANALYSIS

Quality and risk of bias were assessed using the Agency for Healthcare Research and Quality assessment. Indicators were pooled with random or fixed effect meta-analysis based on heterogeneity and sub-grouped analysed by the biopsy site.

MAIN RESULTS

Thirty cross-sectional studies were included, comprising 840 POP cases and 755 controls. Overall results showed that the expression of type III collagen (COLIII) and several matrix metalloproteinases (MMP-1, -2 and -9) were increased, whereas those of type I collagen (COLI), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were decreased in patients with POP. Subgroup analysis showed that the expression of COLIII in the anterior vaginal wall (AVW) and COLIII, MMP-2 and -9 in the uterosacral ligament (USL) were consistent with the overall results. However, the expression of COLI and MMP-1 in the AVW showed no difference and the expression of COLI and MMP-1 in the USL is still controversial based on current studies.

CONCLUSIONS

Patients with POP have lower expression of COLI and TIMP-1 and higher expression of COLIII and MMPs compared with non-POP cases, but further studies are required to investigate in specified anatomical sites.

Exosomes derived from mesenchymal stromal cells: a promising treatment for pelvic floor dysfunction

Pelvic floor dysfunction (PFDs), which include pelvic organ prolapse (POP), stress urinary incontinence (SUI) and anal incontinence (AI), are common degenerative diseases in women that have dramatic effects on quality of life. The pathology of PFDs is based on impaired pelvic connective tissue supportive strength due to an imbalance in extracellular matrix (ECM) metabolism, the loss of a variety of cell types, such as fibroblasts, muscle cells, peripheral nerve cells, and oxidative stress and inflammation in the pelvic environment. Fortunately, exosomes, which are one of the major secretions of mesenchymal stromal cells (MSCs), are involved in intercellular communication and the modulation of molecular activities in recipient cells via their contents, which are bioactive proteins and genetic factors such as mRNAs and miRNAs. These components modify fibroblast activation and secretion, facilitate ECM modelling, and promote cell proliferation to enhance pelvic tissue regeneration. In this review, we focus on the molecular mechanisms and future directions of exosomes derived from MSCs that are of great value in the treatment of PFD.

Age and/or postmenopausal status as risk factors for pelvic organ prolapse development: systematic review with meta-analysis

INTRODUCTION AND HYPOTHESIS

Age is named as a risk factor for pelvic organ prolapse (POP), despite not being the primary outcome for many observational studies. Postmenopausal status is another associated factor but has many confounders. We aimed to systematically review the role of age and/or postmenopausal status in POP development.

METHODS

Systematic review addressing age and hormones, more specifically by postmenopausal status, from inception to March 2020 in four databases (PubMed, Embase, WOS, Cochrane Library). Quality of evidence was classified by the ROBINS-I classification for non-randomized studies. Experimental studies, animal studies, studies linking age with recurrent POP and case series were excluded. Effect estimates were collected from adjusted odds ratio plus 95% confidence intervals. Significance level was 5%. A discussion exploring mechanistic factors was also included.

RESULTS

Nineteen studies (11 cross sectional, 6 cohort and 2 case control) were included for quantitative analysis. Only two studies presented a low overall risk of bias for age; most of the domains were of moderate risk. Every additional year was responsible for a 10% increase in the risk to develop POP (OR = 1.102 [1.021-1.190]; i² = 80%, random analysis, p = 0.012). This trend was confirmed when age was dichotomized into a cutoff of 35 (p = 0.035) and 50 (p < 0.001) years. Although an increase in the risk for POP was noted in postmenopausal women, this did not reach statistical significance (OR = 2.080 [0.927-4.668], i² = 0%, p = 0.076).

CONCLUSION

Age is a risk factor for POP; postmenopausal status was not statistically associated with POP, prompting the need for further studies addressing this factor.

Mechanics of Uterosacral Ligaments: Current Knowledge, Existing Gaps, and Future Directions

The uterosacral ligaments (USLs) are important anatomical structures that support the uterus and apical vagina within the pelvis. As these structures are over-stretched, become weak, and exhibit laxity, pelvic floor disorders such as pelvic organ prolapse occur. Although several surgical procedures to treat pelvic floor disorders are directed toward the USLs, there is still a lot that is unknown about their function. This manuscript presents a review of the current knowledge on the mechanical properties of the USLs. The anatomy, microstructure, and clinical significance of the USLs are first reviewed. Then, the results of published experimental studies on the in vivo and ex vivo, uniaxial and biaxial tensile tests are compiled. Based on the existing findings, research gaps are identified and future research directions are discussed. The purpose of this exhaustive review is to help new researchers navigate scientific literature on the mechanical properties of the USLs. The use of these structures remains very popular in reconstructive surgeries that restore and augment the support of pelvic organs, especially as synthetic surgical mesh implants continue to be highly controversial.

Single-cell transcriptome profiling of the vaginal wall in women with severe anterior vaginal prolapse

Anterior vaginal prolapse (AVP) is the most common form of pelvic organ prolapse (POP) and has deleterious effects on women's health. Despite recent advances in AVP diagnosis and treatment, a cell atlas of the vaginal wall in AVP has not been constructed. Here, we employ single-cell RNA-seq to construct a transcriptomic atlas of 81,026 individual cells in the vaginal wall from AVP and control samples and identify 11 cell types. We reveal aberrant gene expression in diverse cell types in AVP. Extracellular matrix (ECM) dysregulation and immune reactions involvement are identified in both non-immune and immune cell types. In addition, we find that several transcription factors associated with ECM and immune regulation are activated in AVP. Furthermore, we reveal dysregulated cell-cell communication patterns in AVP. Taken together, this work provides a valuable resource for deciphering the cellular heterogeneity and the molecular mechanisms underlying severe AVP.

From molecular to macro: the key role of the apical ligaments in uterovaginal support

To explain the pathophysiology of pelvic organ prolapse, we must first understand the complexities of the normal support structures of the uterus and vagina. In this review, we focus on the apical ligaments, which include the cardinal and uterosacral ligaments. The aims of this review are the following: (1) to provide an overview of the anatomy and histology of the ligaments; (2) to summarize the imaging and biomechanical studies of the ligament properties and the way they relate to anterior and posterior vaginal wall prolapse; and (3) to synthesize these findings into a conceptual model for the progression of prolapse.

Genome‑wide DNA methylation analysis of uterosacral ligaments in women with pelvic organ prolapse

Pelvic organ prolapse (POP) is an increasingly serious health problem that impairs quality of life and is caused by multiple additive genetic and environmental factors. As the uterosacral ligaments (ULs) provide primary support for the pelvic organs, it was hypothesized that disruption of these ligaments (as a result of aberrant methylation) may lead to a loss of support and eventually contribute to POP. In the present study, whether there are any aberrant methylations in the ULs of patients with POP compared to those of controls was investigated. Genomic DNA was isolated from the ULs of five women with POP and four women without POP, as controls, undergoing hysterectomy for benign conditions. An Illumina Infinium Methylation EPICBeadChips Infinium Human Methylation 850 K bead array was used to investigate the total methylation in the ULs. There were 3,723 differentially methylated CpG sites (Δβ<0.14; P<0.05), including 3,576 hypermethylation and 147 hypomethylation sites in the ULs of patients with POP compared with the normal controls. There were more hypermethylated CpG sites, but a high ratio of hypomethylation between CpG islands and the N-shelf; in the gene structure, there was more hypermethylation than hypomethylation in TSS1500 and the 5′ untranslated region. Gene ontology analysis demonstrated that these differentially methylated genes were associated with ‘cell morphogenesis’, ‘extracellular matrix’, ‘cell junction’, ‘protein binding’ and ‘guanosine triphosphatase activity’. Several significant pathways were identified, including ‘focal adhesion’ and ‘extracellular matrix-receptor interaction pathway’. This study provides evidence that there are differences in genome-wide DNA methylation between ULs in menopausal women with and without POP, and that epigenetic mechanisms may partly contribute to POP pathogenesis.

Matrix Metalloproteinase-1 Expression in Women With and Without Pelvic Organ Prolapse: A Systematic Review and Meta-analysis

This meta‐analysis was conducted to estimate the association between matrix metalloproteinase‐1 (MMP‐1) expression and pelvic organ prolapse (POP) in women. Relevant studies published before 6 December 2015 were identified by searching PubMed, Ovid, EBSCO, and EMBASE. A total number of five case–control studies, including 182 POP cases and 192 controls, were identified. The results indicated that women without POP had a lower MMP‐1 level of expression compared with women with POP (odds ratio = 0.54, 95% confidence interval: 0.43–0.67, P = 0.000). After stratification by biopsy site, ethnicity, or menopausal status, this finding was also confirmed in the subgroup analysis with no significant changes. Egger's linear regression test revealed a potential publication bias (P = 0.028). The findings of our study indicate that women who suffer from POP have a higher expression level of MMP‐1 than women without POP.

3D finite element modeling of pelvic organ prolapse

OBJECTIVES

The purpose of this study is to develop a validated 3D finite element model of the pelvic floor system which can offer insights into the mechanics of anterior vaginal wall prolapse and have the ability to assess biomedical device treatment methods. The finite element results should accurately mimic the clinical findings of prolapse due to intra-abdominal pressure (IAP) and soft tissues impairment conditions.

METHODS

A 3D model of pelvic system was created in Creo Parametric 2.0 based on MRI Images, which included uterus, cervix, vagina, cardinal ligaments, uterosacral ligaments, and a simplified levator plate and rectum. The geometrical model was imported into ANSYS Workbench 14.5. Mechanical properties of soft tissues were based on experimental data of tensile test results from current literature. Studies were conducted for IAP loadings on the vaginal wall and uterus, increasing from lowest to extreme values.

RESULTS

Anterior vaginal wall collapse occurred at an IAP value corresponding to maximal valsalva and showed similar collapsed shape as clinical findings. Prolapse conditions exhibited high sensitivity to vaginal wall stiffness, whereas healthy tissues was found to support the vagina against prolapse. Ligament impairment was found to have only a secondary effect on prolapse.

Role of mechanical strain-activated PI3K/Akt signaling pathway in pelvic organ prolapse

Mechanical loading on pelvic supports contributes to pelvic organ prolapse (POP). However, the underlying mechanisms remain to be elucidated. Our previous study identified that mechanical strain induced oxidative stress (OS) and promoted apoptosis and senescence in pelvic support fibroblasts. The aim of the present study is to investigate the molecular signaling pathway linking mechanical force with POP. Using a four-point bending device, human uterosacral ligament fibroblasts (hUSLF) were exposed to mechanical tensile strain at a frequency of 0.3 Hz and intensity of 5333 µε, in the presence or absence of LY294002. The applied mechanical strain on hUSLF resulted in apoptosis and senescence, and decreased expression of procollagen type I α1. Mechanical strain activated phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt signaling and resulted in downregulated expression of glutathione peroxidase 1 and Mn-superoxide dismutase, and accumulation of intracellular reactive oxygen species. These effects were blocked by administration of LY294002. Furthermore, it was demonstrated that PI3K/Akt was activated in the uterosacral ligaments of POP patients, and that OS was increased and collagen type I production reduced. The results from the present study suggest that mechanical strain promotes apoptosis and senescence, and reduces collagen type I production via activation of PI3K/Akt-mediated OS signaling pathway in hUSLF. This process may be involved in the pathogenesis of POP as it results in relaxation and dysfunction of pelvic supports.