Advances in molecular mechanisms of pelvic organ prolapse (Review)

The Application of Shear Wave Elastography to Determine the Elasticity of the Levator Ani Muscle and Vaginal Tissue in Patients With Pelvic Organ Prolapse

OBJECTIVES

The changes of the extracellular matrix of the connective tissue have significantly contributed to the incidence of pelvic organ prolapse (POP). It seems reasonable that sonoelastography could be a useful tool to evaluate the elasticity of pelvic floor tissue in patients with POP and compare it to those without POP. The main aim of this pilot study was to determine if there are differences in the elasticity of the levator ani muscle (LAM) and vaginal tissue between patients with and without POP.

METHODS

Prospective observation study, including 60 patients (30 with POP and 30 without POP). Sonoelastography was performed to evaluate the elasticity (in kilopascals, kPa) of the following regions of interest: vagina at the level of middle third of the urethra; vagina at the level of the bladder trigone; vagina in the anterior and posterior fornix; vagina at the level of middle third of the anorectal canal; posterior third of the LAM.

RESULTS

A total of 60 patients completed the study (30 with POP, 30 without POP). In the POP group, 18/30 (60%) had an anterior vaginal wall prolapse, 3/30 (10%) a uterine prolapse, 15/30 (50%) a rectocele, and 6/30 (20%) a enterocele. Patients with POP had higher elasticity in all anatomical study areas, with statistically significant differences in the anterior fornix (13.6 vs 11.2 kPa; P: .012). A multiple regression (controlling age, menopausal stage, and parity) allowed to detect statistically significant differences in the elasticity of the middle third of the urethra (P: .03) and the middle third of the anorectal canal (P: .019).

CONCLUSION

It is possible to evaluate the elasticity of the LAM and vaginal tissue using sonoelastography, detecting a higher elasticity in patients with POP than in those without POP.

The alteration of apoptosis-related genes in female pelvic supportive tissues with regard to menopausal status

PURPOSE

We aimed to compare the expression levels of anti-apoptotic and proapoptotic genes in the parametrium, sacrouterine and round ligaments with respect to menopausal status in women presenting without any indication of pelvic organ prolapse (POP). We hypothesized that apoptosis related gene expressions in female pelvic tissues may be altered during menopause.

METHODS

The study groups consisted of pre-menopausal (n = 10) and menopausal (n = 10) females who did not have POP symptoms. Three different types of tissue samples (Parametrium, Round Ligament and Sacrouterine Ligament) were obtained and RNA was isolated from these tissues. After purifying and quantifying RNA samples, qPCR was used to determine the expression levels of anti-apoptotic and pro-apoptotic genes.

RESULTS

BCL-2 gene expression levels were significantly lower in all the tissues of menopausal patients compared to those of premenopausal patients. In comparison to premenopausal patients, the sacrouterine ligament tissue BAD expression level was significantly high (p = 0.035), and the BCL-2/BAD ratio was significantly lower in menopausal patients (p = 0.006).

CONCLUSION

Apoptosis-related protein levels change during menopause; pro-apoptotic gene expressions decrease and anti-apoptotic gene expressions increase. The significant alteration of BCL-2 and BAD expression in sacrouterine ligament with respect to menopausal status was observed and this suggested that when compared to other pelvic tissues, the sacrouterine ligament, which plays a crucial role for genital organs in restoring normal pelvic anatomy and providing support, could be affected more by menopause.

Estrogen inhibits the differentiation of fibroblasts induced by high stiffness matrix by enhancing DNMT1 expression

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse(POP) is a multifactorial connective tissue disorder caused by damage to the supporting structures of the pelvic floor. Evidence from several studies suggests that anterior vaginal wall stiffness is higher in patients with POP, but the mechanisms involved remain unknown.

METHODS

Tissue from the anterior vaginal wall of patients with POP or other benign diseases was obtained. The modulus of elasticity of the anterior vaginal wall was measured using a microindenter. Cells were cultured in vitro on acrylamide gels of different stiffness and treated with DNMT1 inhibitor, microtubule polymerisation inhibitor and estrogen. Western blot or immunohistochemical staining was performed to detect DNA Methyltransferase 1, α-smooth muscle actin(α-SMA) expression, and connective tissue growth factor(CTGF) expression.

CONCLUSION

Estrogen can inhibit high stiffness matrix-induced fibroblast differentiation, by enhancing DNMT1 expression. This study may help to elucidate the complex crosstalk between fibroblasts and their surrounding matrix under healthy and pathological conditions and provide new insights into the options for material-related therapeutic applications.

Knowledge mapping and visualization analysis of pelvic organ prolapse repair with mesh from 2001 to 2021

Aims: In recent decades, extensive attention has been paid to the application of mesh to repair pelvic floor defects. However, a large body of related literature has not been system summarized. The purpose of this study is to summarize and visualize the literature on pelvic organ prolapse (POP) repair with mesh using bibliometrics. Methods: Medical literature regarding POP repair with mesh were searched and obtained in the Web of Science™ Core (WoSCC) database from 2001 to 2021. Microsoft Excel 2020, CiteSpace and VOSviewer were used to conduct the bibliometric and knowledge-map analysis. Results: In the past 20 years, a total of 2,550 articles and reviews have been published in 35 journals, and the published and cited results show a growing trend. Cosson M and International Urogynecology Journal were the authors and journals with the highest output, respectively. The United States, France and the United Kingdom are among the top three countries/organizations in relevant publications in worldwide. 584 key words in the literature are divided into 8 clusters, which are mainly related to prolapse type, risk factors, surgical methods, imaging, quality of life and bioengineering. Using clinical research and tissue engineering technology to reduce mesh complications is the current hot spot in this field. Conclusion: Reasonable application of mesh and avoiding mesh complications are still the most concerned topics in POP research. Although clinical research, surgical improvement, biological mesh and bioengineering technology have shown promising results, it is still urgent to carry out clinical transformation application research.

The protective effect of 17 β-estradiol on human uterosacral ligament fibroblasts from postmenopausal women with pelvic organ prolapse

This study aims to explore the protective effects of 17 β-estradiol on the human uterosacral ligament fibroblasts (hUSLFs) under static or stretched conditions. The experiments were performed on hUSLFs derived from pelvic organ prolapse (POP) and non-POP patients. Fibroblasts were cultured after collagenase digestion and identified by morphological observation and immunocytochemical methods. 17 β-estradiol (10⁻¹⁰ M and 10⁻⁹ M) and mechanical stress induced by the FX-5000 T-cell stress loading system under a loading strain of 1/2 sin waveform uniaxial cyclic stress with a tensile strain of 20% and a frequency of 0.5 Hz were either or both applied on hUSLFs. Cell proliferation was measured by CCK8, and cell apoptosis and death were detected using Annexin V/7-AAD staining and flow cytometric analysis. We found that the fibroblasts growth rate of POP patients was significantly lower than controls. The cell apoptosis and death rate increased as the mechanical load intensifying. After 20% mechanical stretching for 24 h, the dead cell rate was higher in POP than control. Notably, 17 β-estradiol treatment reversed mechanical stress induced hUSLFs apoptosis and death in both POP and Control cells. The protein and mRNA levels of anti-apoptotic PARP1 (poly-ADP-ribose polymerase) and Bcl-2 were increased by estrogen treatment. Meanwhile, expression of estrogen receptor α, a target of Poly-ADP-Ribosylation of PARP1, was also enhanced by 17 β-estradiol under the mechanical load. In conclusion, estrogen application ameliorates the mechanical strain induced cell apoptosis and death in hUSLFs from POP patients. PARP1 might be involved in this protective process, providing novel insights into the mechanical biology of and possible therapies for POP.

Construction of a focal adhesion signaling pathway-related ceRNA network in pelvic organ prolapse by transcriptome analysis

Objective: Pelvic organ prolapse (POP) affects a large proportion of adult women, but the pathogenesis of POP remains unclear. The increase in global population aging will impose a substantial medical burden. Herein, we aimed to explore the related RNAs regulating the occurrence of POP and provide potential therapeutic targets.

Method: Tissue biopsies were collected from the anterior vaginal wall of six women with POP and six matched subjects without POP. The profiles of mRNAs, circRNAs, lncRNAs, and miRNAs were obtained by whole transcriptome RNA sequencing.

Result: The findings revealed that 71 circRNAs, 76 known lncRNAs, 84 miRNAs, and 931 mRNAs were significantly altered (p < 0.05 and |log2FC| > 1). GO and KEGG enrichment analyses indicated that the differentially expressed genes (DEGs) were mainly enriched in the focal adhesion signaling pathway. FLT, ITGA9, VEGFD, PPP1R12B, and ROCK2 were identified as focal adhesion signaling pathway-related hub genes by protein–protein interaction network analysis. Based on the relationships between the DEGs and miRNA, lncRNA and circRNA targets, we constructed a focal adhesion signaling pathway-related ceRNA network. The ceRNA network includes hsa_circ_0002190/hsa_circ_0046843/lnc-CARMN -miR-23a-3p - ROCK2 and hsa_circ_0001326/hsa_circ_0007733/lnc-AC107959/lnc-TPM1-AS - miR-205-5p - ROCK2/PPP1R12B/VEGFD. Moreover, abnormalities in the cytoskeleton in fibroblasts from individuals with POP were observed.

Conclusion: In this study, a focal adhesion signaling pathway-related ceRNA network was constructed, and this network may serve as a target for finding suitable drugs for the treatment of POP.

The difference in collagen type-1 expression in women with and without pelvic organ prolapse: a systematic review and meta-analysis

INTRODUCTION AND HYPOTHESIS

This study was aimed at identifying the difference in collagen type-1 expression in women with and without pelvic organ prolapse (POP).

METHODS

A systematic review and meta-analysis was carried out women with and without pelvic organ prolapse. This meta-analysis was conducted on research articles describing the evaluation of collagen type-1 expression between patients with and without POP. The articles were obtained from PubMed, EBSCO, and ProQuest, and were published between January 2000 and June 2021. Pooled mean difference (MD) and pooled odds ratio (OR) were calculated using fixed effect models. Review Manager (RevMan 5.4) was used to analyze the data. The main outcome measures were pooled MD and pooled OR of collagen type-1 expression in patients with and without POP.

RESULTS

A total of seven case-control studies were included in the meta-analysis using the effect size of the MD and two case-control studies were included in the meta-analysis using the effect size of the OR. A total of 247 POP cases and 132 non-POP cases were identified from the studies. Our study indicated that patients with POP had a lower level of collagen type-1 expression than non-POP patients (MD = -6.77; 95% CI: -8.37, -5.17, p < 0.00001). Patients with low expression of collagen type-1 in pelvic support tissue are at a more than 3 times higher risk of suffering from pelvic organ prolapse (OR = 3.23, 95% CI: 1.52 to 6.87, p = 0.002).

CONCLUSION

The results of this study showed that patients with pelvic organ prolapse have lower expression of collagen type-1 than nonpelvic organ prolapse patients.