Oxidative Stress: A Possible Trigger for 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.

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.

Single-cell analysis of uterosacral ligament revealed cellular heterogeneity in women with pelvic organ prolapse

Pelvic organ prolapse (POP) markedly affects the quality of life of women, including significant financial burden. Using single-cell RNA sequencing, we constructed a transcriptional profile of 30,452 single cells of the uterosacral ligament in POP and control samples, which has never been constructed before. We identified 10 major cell types, including smooth muscle cells, endothelial cells, fibroblasts, neutrophils, macrophages, monocytes, mast cells, T cells, B cells, and dendritic cells. We performed subpopulation analysis and pseudo-time analysis of POP primary cells, and explored differentially expressed genes. We verified previous cell clusters of human neutrophils of uterosacral ligaments. We found a significant reduction in receptor-ligand pairs related to ECM and cell adhesion between fibroblasts and endothelial cells in POP. The transcription factors related to the extracellular matrix, development, and immunity were identified in USL. Here we provide insight into the molecular mechanisms of POP and valuable information for future research directions.

The mechanism of adipose mesenchymal stem cells to stabilize the immune microenvironment of pelvic floor injury by regulating pyroptosis and promoting tissue repair

Pelvic organ prolapse (POP) has a high incidence rate among Chinese women. Repeated mechanical stimulation is an important factor causing POP, but the injury mechanism has not yet been elucidated. The purpose of this study is to explore the related mechanisms of pelvic floor supporting tissue damage caused by mechanical force and the application of stem cell therapy. First, we obtained vaginal wall and sacral ligament tissue samples from clinical patients for examination. Pelvic floor support tissues of POP patients displayed high expression of inflammation and immune disorders. Then, we constructed a rat model of childbirth injury. In vivo and in vitro experiments investigated the key mechanism of pelvic floor support tissue injury caused by mechanical force. We discovered that after mechanical force, a large number of reactive oxygen species (ROS) and macrophages rapidly accumulated in pelvic floor tissues. ROS stimulated macrophages to produce NLRP3 inflammatory complex, induced the release of interleukin (IL-1β) and pyroptosis and exacerbated the inflammatory state of damaged tissues, persisting chronic inflammation of fibroblasts in supporting tissues, thus causing the pelvic floor's extracellular matrix (ECM) collagen metabolic disorder. Resultingly impeding the repair process, thereby causing the onset and progression of the disease. Through their paracrine ability, we discovered that adipose mesenchymal stem cells (ADSCs) could inhibit this series of pathological processes and promote tissue repair, asserting a good therapeutic effect. Simultaneously, to overcome the low cell survival rate and poor therapeutic effect of directly injecting cells, we developed a ROS-responsive PVA@COLI hydrogel with ADSCs. The ROS-scavenging properties of the gel could reshape the site of inflammation injury, enhance cell survival, and play a role in subsequent treatment. The findings of this study could serve as a basis for early, targeted intervention therapy for POP and representing a promising approach.

Quercetin antagonized advanced glycated end products induced apoptosis and functional inhibition of fibroblasts from the prolapsed uterosacral ligament

The altered behaviors and functions of pelvic floor fibroblasts are pathophysiological changes of pelvic organ prolapse (POP). Our previous study showed that advanced glycated end products (AGEs) accumulated in the pelvic tissues of POP and induced fibroblast apoptosis. The study was designed to investigate whether quercetin antagonize AGEs-induced apoptosis and functional inhibition of fibroblasts. The uptake of 5-ethynyl-2'-deoxyuridine (EdU) was evaluated for cell proliferation. Flow cytometric analysis was applied for cell apoptosis. Intracellular reactive oxygen species (ROS) content was determined by the fluorescence of dichlorofluorescein (DCF). The contractility of fibroblasts was measured by collagen gel contraction assay. The expressions of extracellular matrix (ECM) related genes and the expression of miR-4429 and caspase-3 were quantified by qPCR. The expressions of phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K), serine-threonine kinase (Akt), and phosphorylated Akt (p-Akt) were analyzed by Western Blot. The down-regulation of miR-4429 was achieved by cell transfection. Quercetin antagonized AGEs-induced apoptosis, proliferation inhibition, and ROS increase in fibroblasts. Quercetin did not alleviate AGEs-induced contractile impairment of fibroblasts. Quercetin reduced the gene expressions of lysyl oxidase like protein 1 (LOXL1)and matrix metallopeptidase 1 (MMP1), and increased the gene expressions of lysyl oxidase (LOX) and fibrillin 2 (FBN2) in fibroblasts. Quercetin reversed AGEs-induced upregulation of PTEN and downregulation of PI3K, P-Akt, and miR-4429 in fibroblasts. The inhibitory effect of quercetin on AGEs-induced fibroblast apoptosis was inhibited by downregulating the expression of miR-4429. In conclusion, quercetin antagonized AGEs-induced apoptosis and functional inhibition of fibroblasts from the prolapsed uterosacral ligament. And inhibiting AGEs-induced down-regulation of miR-4429/PTEN/PI3K/Akt pathway was the mechanism underlying the antagonistic effect of quercetin on AGEs-induced apoptosis.

4D DIA-PRM proteomic study identifying modulated pathways and biomarkers associated with pelvic organ prolapse

Pelvic organ prolapse (POP) is a highly disabling condition that negatively affects the quality of life of millions of women worldwide. However, the underlying mechanisms associated with the development and progression of the disease remain poorly understood. Here, an untargeted four-dimensional data-independent acquisition (4D DIA)-based proteomics approach was applied to vaginal wall tissue samples from POP (n = 19) and control (n = 8) patients to identify potential diagnostic biomarker(s) for POP and examine the molecular mechanisms underlying the disease. Of the 5713 tissue proteins that were detected, 1957 proteins were significantly changed in POP patients. Further bioinformatics analysis revealed that multiple biological processes including protein digestion & absorption, retrograde endocannabinoid signaling, tyrosine metabolism, and nucleotide metabolism were significantly enriched and associated with the pathogenesis of POP. Interestingly, 16 of these differentially expressed proteins associated with four pathways were also identified by targeted parallel reaction monitoring (PRM) proteomics analysis on the same 27 tissue samples. Changes in 94 % (15/16) of these proteins were consistent with the 4D DIA data. Furthermore, most proteins displayed good diagnostic accuracy with high area under the curve (AUC) values (AUC＞0.8). Specifically, five proteins including ELN, COL6A2, ENTPD1, AOC3, and COX7A2 distinguished between POP and control patients with very high accuracy (AUC ≥ 0.95) in both 4D DIA and PRM analyses, and may therefore be potential diagnostic biomarkers for POP. In summary, the present study not only provided several potential biomarker(s) for effective POP diagnosis, but extended our knowledge of the key regulatory pathways associated with the disease.

Ferrostatin-1 alleviates the damage of C2C12 myoblast and mouse pelvic floor muscle induced by mechanical trauma

Ferroptosis is a special form of regulated cell death, which is reported to play an important role in a variety of traumatic diseases by promoting lipid peroxidation and devastating cell membrane structure. Pelvic floor dysfunction (PFD) is a kind of disease affecting the quality and health of many women's lives, which is closely related to the injury of the pelvic floor muscle. Clinical findings have discovered that there is anomalous oxidative damage to the pelvic floor muscle in women with PFD caused by mechanical trauma, but the specific mechanism is still unclear. In this study, we explored the role of ferroptosis-associated oxidative mechanisms in mechanical stretching-induced pelvic floor muscle injury, and whether obesity predisposed pelvic floor muscle to ferroptosis from mechanical injury. Our results, in vitro, showed that mechanical stretch could induce oxidative damage to myoblasts and trigger ferroptosis. In addition, glutathione peroxidase 4 (GPX4) down-regulation and 15-lipoxygenase 1(15LOX-1) up-regulation exhibited the same variational characteristics as ferroptosis, which was much more pronounced in palmitic acid (PA)-treated myoblasts. Furthermore, ferroptosis induced by mechanical stretch could be rescued by ferroptosis inhibitor (ferrostatin-1). More importantly, in vivo, we found that the mitochondria of pelvic floor muscle shrank, which were consistent with the mitochondrial morphology of ferroptosis, and GPX4 and 15LOX-1 showed the same change observed in cells. In conclusion, our data suggest ferroptosis is involved in the injury of the pelvic floor muscle caused by mechanical stretching, and provide a novel insight for PFD therapy.

Identification of the genetic basis of sow pelvic organ prolapse

Introduction: Pelvic organ prolapse (POP) is one contributor to recent increases in sow mortality that have been observed in some populations and environments, leading to financial losses and welfare concerns. Methods: With inconsistent previous reports, the objective here was to investigate the role of genetics on susceptibility to POP, using data on 30,429 purebred sows, of which 14,186 were genotyped (25K), collected from 2012 to 2022 in two US multiplier farms with a high POP incidence of 7.1% among culled and dead sows and ranging from 2% to 4% of all sows present by parity. Given the low incidence of POP for parities 1 and >6, only data from parities 2 to 6 were retained for analyses. Genetic analyses were conducted both across parities, using cull data (culled for POP versus another reason), and by parity, using farrowing data. (culled for POP versus culled for another reason or not culled). Results and Discussion: Estimates of heritability from univariate logit models on the underlying scale were 0.35 ± 0.02 for the across-parity analysis and ranged from 0.41 ± 0.03 in parity 2 to 0.15 ± 0.07 in parity 6 for the by-parity analyses. Estimates of genetic correlations of POP between parities based on bivariate linear models indicated a similar genetic basis of POP across parities but less similar with increasing distance between parities. Genome wide association analyses revealed six 1 Mb windows that explained more than 1% of the genetic variance in the across-parity data. Most regions were confirmed in several by-parity analyses. Functional analyses of the identified genomic regions showed a potential role of several genes on chromosomes 1, 3, 7, 10, 12, and 14 in susceptibility to POP, including the Estrogen Receptor gene. Gene set enrichment analyses showed that genomic regions that explained more variation for POP were enriched for several terms from custom transcriptome and gene ontology libraries. Conclusion: The influence of genetics on susceptibility to POP in this population and environment was confirmed and several candidate genes and biological processes were identified that can be targeted to better understand and mitigate the incidence 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.