Uterosacral ligament smooth muscle cell apoptosis is increased in women with uterine prolapse

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse (POP) involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity, and vaginal structure is an essential factor. In POP, the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and functions. The intricate etiology of POP and the prohibition of transvaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy development. Human umbilical cord mesenchymal stromal cells (hucMSCs) present limitations, but their exosomes (hucMSC-Exo) are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix remodeling.

AIM

To investigate the effects of hucMSC-Exo on the functions of primary vaginal fibroblasts and to elucidate the underlying mechanism involved.

METHODS

Human vaginal wall collagen content was assessed by Masson's trichrome and Sirius blue staining. Gene expression differences in fibroblasts from patients with and without POP were assessed via RNA sequencing (RNA-seq). The effects of hucMSC-Exo on fibroblasts were determined via functional experiments in vitro. RNA-seq data from fibroblasts exposed to hucMSC-Exo and microRNA (miRNA) sequencing data from hucMSC-Exo were jointly analyzed to identify effective molecules.

RESULTS

In POP, the vaginal wall exhibited abnormal collagen distribution and reduced fibroblast 1 quality and quantity. Treatment with 4 or 6 μg/mL hucMSC-Exo suppressed inflammation in POP group fibroblasts, stimulated primary fibroblast growth, and elevated collagen I (Col1) production in vitro. High-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11 (MMP11) expression.

CONCLUSION

HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in vitro. Abundant miRNAs in hucMSC-Exo targeted and downregulated MMP11 expression. HucMSC-Exo-based therapy may be ideal for safely and effectively treating POP.

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse (POP) involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity, and vaginal structure is an essential factor. In POP, the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and functions. The intricate etiology of POP and the prohibition of transvaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy development. Human umbilical cord mesenchymal stromal cells (hucMSCs) present limitations, but their exosomes (hucMSC-Exo) are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix remodeling.

AIM

To investigate the effects of hucMSC-Exo on the functions of primary vaginal fibroblasts and to elucidate the underlying mechanism involved.

METHODS

Human vaginal wall collagen content was assessed by Masson’s trichrome and Sirius blue staining. Gene expression differences in fibroblasts from patients with and without POP were assessed via RNA sequencing (RNA-seq). The effects of hucMSC-Exo on fibroblasts were determined via functional experiments in vitro. RNA-seq data from fibroblasts exposed to hucMSC-Exo and microRNA (miRNA) sequencing data from hucMSC-Exo were jointly analyzed to identify effective molecules.

RESULTS

In POP, the vaginal wall exhibited abnormal collagen distribution and reduced fibroblast 1 quality and quantity. Treatment with 4 or 6 μg/mL hucMSC-Exo suppressed inflammation in POP group fibroblasts, stimulated primary fibroblast growth, and elevated collagen I (Col1) production in vitro. High-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11 (MMP11) expression.

CONCLUSION

HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in vitro. Abundant miRNAs in hucMSC-Exo targeted and downregulated MMP11 expression. HucMSC-Exo-based therapy may be ideal for safely and effectively treating POP.

Effect of Vaginal Microecological Alterations on Female Pelvic Organ Prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to investigate the correlation between endogenous vaginal microecological alterations and female pelvic organ prolapse (POP).

METHODS

Patients who underwent vaginal hysterectomy were retrospectively analyzed as the POP group (n = 30) and the non-POP group (n = 30). The vaginal microbial metabolites and enzyme levels were tested using the dry chemoenzymatic method. The mRNA and protein expression were tested using real-time quantitative PCR and immunohistochemistry. SPSS version 25.0 and GraphPad Prism 8.0 were performed for statistical analysis.

RESULTS

Compared with the non-POP group, the vaginal pH, H2O2 positivity and leukocyte esterase positivity were higher in patients with POP (all p < 0.05). Further analysis showed that patients with pelvic organ prolapse quantification (POP-Q) stage IV had higher rates of vaginal pH, H2O2 positivity and leukocyte esterase positivity than those with POP-Q stage III. Additionally, the mRNA expression of decorin (DCN), transforming growth factor beta 1 (TGF-β1), and matrix metalloproteinase-3 (MMP-3) in uterosacral ligament tissues were higher, whereas collagen I and III were lower. Similarly, the positive expression of MMP-3 in uterosacral ligament tissue was significantly upregulated in the POP group compared with the non-POP group (p = 0.035), whereas collagen I (p = 0.004) and collagen III (p = 0.019) in uterosacral ligament tissue were significantly downregulated in the POP group. Correlation analysis revealed that there was a significant correlation between vaginal microecology and collagen metabolism. In addition, MMP-3 correlated negatively with collagen I and collagen III (p = 0.002, r = -0.533; p = 0.002, r = -0.534 respectively), whereas collagen I correlated positively with collagen III (p = 0.001, r = 0.578).

CONCLUSIONS

Vaginal microecological dysbiosis affects the occurrence of female POP, which could be considered a novel therapeutic option.

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.

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.

Emerging trends on the mechanism of pelvic organ prolapse from 1997 to 2022: visualization and bibliometric analysis

Objective

At present, there is no feature description of the mechanism of pelvic organ prolapse (POP) in the literature. This study aimed to map the emerging trends regarding the mechanism of POP from inception to 2022 by bibliometric analysis and to analyze its research hotspots and frontiers.

Methods

We downloaded pertinent publications from inception to 2022 from the Web of Science Core Collection (WoSCC) on 30 June 2022. The data were then examined using the Bibliometrix program in R (Version 4.1.0), CiteSpace software, the Online Analysis Platform of Literature Metrology (https://bibliometric.com), and a bibliometrix online interface.

Results

A total of 290 qualified records on the mechanism of POP were identified and included in the analysis. The most productive journal was International Urogynecology Journal. Bump RC and Olsen AL were the most cited authors. Extracellular matrix, collagen, apoptosis, elastin, oxidative stress, gene expression, matrix metalloproteinase, and tissue engineering were among the 25 most relevant terms. According to the analysis of trending topics, tissue engineering has become a new research hotspot.

Conclusion

Extracellular matrix remodeling, oxidative stress and apoptosis are the three main directions for studying the mechanism of POP. In addition, tissue engineering has become a new research hotspot. In the future, in-depth research on the interaction between different mechanisms will be carried out, and attempts will be made to combine biomimetic materials and seed cells to achieve the regeneration and reconstruction of POP-related organs.

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.

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.

Using the novel pelvic organ prolapse histologic quantification system to identify phenotypes in uterosacral ligaments in women with pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse is common, but the underlying etiologies are poorly understood, which limits our current prevention and treatment options.

OBJECTIVE

Our primary objective was to compare the uterosacral ligament histologic features in women with and without prolapse using the novel pelvic organ prolapse histologic quantification system. Our secondary aim was to determine whether composite histologic findings in uterosacral ligaments are associated with prolapse risk factors.

STUDY DESIGN

This was a prospective cohort study in which paracervical uterosacral ligament biopsies were performed at the time of hysterectomy for primary prolapse or other benign gynecologic indications and processed for histologic evaluation. The pelvic organ prolapse quantification system was used to determine the prolapse stage. In this study, 9 prominent histologic features were semiquantitatively scored using the pelvic organ prolapse histologic quantification system in a blinded fashion and compared between prolapse and control groups. Unbiased principal component analysis of these scores was independently performed to identify potential relationships between histologic measures and prolapse risk factors.

RESULTS

The histologic scores of 81 prolapse and 33 control ligaments were analyzed. Compared with the control group, women in the prolapse group were significantly older and more likely to be in the menopausal phase. There was no difference in the number of vaginal deliveries, body mass index, hormone use, or smoking status between the groups. To control for baseline differences, patients were also stratified by age over 40 years and menopausal status. Compared with the control group, the prolapse ligaments in the premenopausal group had significantly more loss of smooth muscle fibers within the fascicles (P<.001), increased inflammatory infiltrates of neutrophils within the tissue and perineural inflammatory cells (P<.01 and P=.04, respectively), and reduced neointimal hyperplasia (P=.02). Prolapse ligaments in the postmenopausal group exhibited elevated adipose content compared with that of the control group (P=.05). Amount of fibrillar collagen, total nonvascular smooth muscle, and muscle fiber vesicles of prolapse ligaments did not differ in either the premenopausal or postmenopausal group compared with that of the control group. Unbiased principal component analysis of the histologic scores separated the prolapse ligaments into 3 phenotypes: (1) increased adipose accumulation, (2) increased inflammation, and (3) abnormal vasculature, with variable overlap with controls. Posthoc analysis of these subgroups demonstrated a positive correlation between increasing number of vaginal deliveries and body mass index with increasing adipose content in the adipocyte accumulation and inflammatory phenotype and increasing neointimal hyperplasia in the vascular phenotype. However, only the relationship between vaginal delivery and adipocytes was significant in the adipose phenotype (R²=0.13; P=.04).

CONCLUSION

Histologic phenotypes exist in pelvic support ligaments that can be distinguished using the pelvic organ prolapse histologic quantification system and principle component analysis. Vaginal delivery is associated with aberrant adipose accumulation in uterosacral ligaments. Our findings support a multifactorial etiology for pelvic organ prolapse contributing to altered smooth muscle, vasculature, and connective tissue content in crucial pelvic support structures. To confirm these associations and evaluate the biomechanical properties of histologic phenotypes of prolapse, larger studies are warranted. Closing this gap in knowledge will help optimize personalized medicine and help identify targets for prevention and treatment of this complex condition.

Oxidative status of cardinal ligament in pelvic organ prolapse

Pelvic organ prolapse (POP) is a common and distressing health problem in adult women, but the pathophysiological mechanism is yet to be fully elucidated. Previous studies have indicated that oxidative stress may be associated with POP. Thus, the aim of the present study was to investigate the oxidative status of pelvic supportive tissue in POP and further demonstrate that oxidative stress is associated with the pathogenesis of POP. A total of 60 samples were collected from females undergoing hysterectomy for POP or cervical intraepithelial neoplasia (CIN). This included 16 females with POP II, 24 females with POP III–IV (according to the POP-Q system) and 20 females with CIN II–III as the control group. Immunohistochemistry was utilized to measure the expression of oxidative biomarkers, 8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxynonenal (4-HNE). Major antioxidative enzymes, mitochondrial superoxide dismutase (MnSOD) and glutathione peroxidase 1 (GPx1) were measured through reverse transcription-quantitative polymerase chain reaction, western blotting and enzyme activity assays. The results demonstrated that in the cardinal ligament, the expression of 8-OHdG and 4-HNE was higher in the POP III–IV group compared with the POP II group and control group. The MnSOD and GPx1 protein level and enzyme activity were lower in the POP III–IV group compared with the POP II or the control group, while the mRNA expression level of MnSOD and GPx1 was increased. In conclusion, oxidative damage is increased in the pelvic supportive ligament of female patients with POP and the antioxidative defense capacity is decreased. These results support previous findings that oxidative stress is involved in the pathogenesis of POP.

Hypoxia Induces Apoptosis through HIF-1α Signaling Pathway in Human Uterosacral Ligaments of Pelvic Organ Prolapse

The purpose of this study is to evaluate the expression of hypoxia-inducible factor-1α (HIF-1α) in women uterosacral ligament tissues with pelvic organ prolapse and women with normal uterine support structures and illuminate its relationship with apoptosis. Samples were collected from 38 women with pelvic organ prolapse and 31 age matched controls. The expression levels of HIF-1α and BNIP3 in the uterosacral ligaments were measured using immunohistochemistry, qRT-PCR, and Western blot. To assess apoptosis we performed TUNEL assay and Western blot analyses. Lastly, the short form of the Pelvic Floor Impact Questionnaire-7 (PFIQ-7) was used to evaluate prognosis of surgical patients and twenty patients finished the follow-up. The expressions of HIF-1α and BNIP3 in the uterosacral ligaments were significantly higher in patients with pelvic organ prolapse than in control group. Pearson's correlation test revealed significant positive correlations between HIF-1α and apoptosis index. Similarly, Western blot analysis showed the expression of proapoptosis proteins (Bax and Bad), Cytochrome-c, cleaved caspase-3, and caspase-9 in patients with pelvic organ prolapse was upregulated. The PFIQ-7 scores were higher in HIF-1α positive group than in the negative group. Hypoxia may contribute to the pathological process of pelvic organ prolapse by increasing apoptosis via activating HIF-1α signaling pathway.

Recent Advances in Understanding Pelvic-Floor Tissue of Women With and Without Pelvic Organ Prolapse: Considerations for Physical Therapists

Pelvic organ prolapse is a fairly common condition that imposes significant symptoms, diminished quality of life, social burden, financial expense, and surgical risk on women. As evidence supporting the benefit of pelvic-floor muscle training in nonsurgical management of pelvic organ prolapse grows, physical therapists are becoming a provider of choice interacting with women affected by pelvic organ prolapse. This perspective article will review recent research on tissue characteristics of 3 key components of pelvic organ support: skeletal muscle, ligament, and vaginal wall. This information will be summarized as implications for physical therapists. An improved understanding of pelvic-floor tissue in women with and without pelvic organ prolapse will provide a more comprehensive appreciation of the interaction of multiple systems in the disorder.

Proteomic Analysis of the Uterosacral Ligament in Postmenopausal Women with and without Pelvic Organ Prolapse

BACKGROUND

Pelvic organ prolapse (POP) is a major health problem in adult women that involves many factors. No proteomic analysis has been conducted exclusively in POP patients. This study aimed to identify the differential expression of proteins that may be involved in POP by proteomic analysis.

METHODS

Samples of the uterosacral ligament (USL) were collected from five POP patients and five non-POP patients matched according to age, parity, and menopausal status and analyzed using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the mRNA expression of proteins that showed differential expression in the proteomic analyses.

RESULTS

Proteins differentially expressed between POP and non-POP patients were detected. Eight proteins that were down-regulated in the POP group were identified by MALDI-TOF-MS. These proteins included electron transfer flavoprotein, apolipoprotein A-I, actin, transgelin, cofilin-1, cyclophilin A, myosin, and galectin-1, and their expression was verified by qRT-PCR.

CONCLUSION

Using comparative proteomics, we identified eight differentially expressed proteins (including four cytoskeleton proteins and three proteins related to apoptosis) in the USL that may be involved in apoptosis associated with the tissue effects in POP pathophysiology.

Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament‑derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse

Pelvic organ prolapse (POP) is a global health problem, for which the pathophysiological mechanism remains to be fully elucidated. The loss of extracellular matrix protein has been considered to be the most important molecular basis facilitating the development of POP. Oxidative stress (OS) is a well-recognized mechanism involved in fiber metabolic disorders. The present study aimed to clarify whether OS exists in the uterosacral ligament (USL) with POP, and to investigate the precise role of OS in collagen metabolism in human USL fibroblasts (hUSLFs). In the present study, 8-hydroxyguanosine (8-OHdG) and 4 hydroxynonenal (4-HNE), as oxidative biomarkers, were examined by immunohistochemistry to evaluate oxidative injury in USL sections in POP (n=20) and non-POP (n=20) groups. The primary cultured hUSLFs were treated with exogenous H₂O₂ to establish an original OS cell model, in which the expression levels of collagen, type 1, α1 (COL1A1), matrix metalloproteinase (MMP)-2, tissue inhibitor of metalloproteinase (TIMP)-2 and transforming growth factor (TGF)-β1 were evaluated by western blot and reverse transcription-quantitative polymerase chain reaction analyses. The results showed that the expression levels of 8-OHdG and 4-HNE in the POP group were significantly higher, compared with those in the control group. Collagen metabolism was regulated by H₂O₂ exposure in a concentration-dependent manner, in which lower concentrations of H₂O₂ (0.1–0.2 mM) stimulated the anabolism of COL1A1, whereas a higher concentration (0.4 mM) promoted catabolism. The expression levels of MMP-2, TIMP-2 and TGF-β1 exhibited corresponding changes with the OS levels. These results suggested that OS may be involved in the pathophysiology of POP by contributing to collagen metabolic disorder in a severity-dependent manner in hUSLFs, possibly through the regulation of MMPs, TIMPs and TGF-β1 indirectly.

Association between the poly(ADP-ribose) polymerase-1 gene polymorphism and advanced pelvic organ prolapse

OBJECTIVE

Apoptotic cell death, probably induced by oxidative stress, contributes to the development of pelvic organ prolapse. Because poly(ADP-ribose) polymerase-1 is an important mediator of cellular response to oxidative stress, genetic variations in the poly(ADP-ribose) polymerase-1 gene may play a role in the pathogenesis of pelvic organ prolapse. This study aimed to determine the association between advanced pelvic organ prolapse and Val762Ala polymorphism in the poly(ADP-ribose) polymerase-1 gene.

METHODS

A total of 340 women were enrolled in the study. The pelvic organ prolapse group consisted of 185 women with stage III or IV pelvic organ prolapse, whereas the control group consisted of 155 postmenopausal women with stage 0 or I pelvic organ prolapse who visited the hospital for treatment of benign gynecologic disease or routine gynecologic checkup. Genotyping of the poly(ADP-ribose) polymerase-1 Val762Ala polymorphism was performed by real-time polymerase chain reaction analysis using a TaqMan assay.

RESULTS

Genotype distribution in the pelvic organ prolapse group was different from that in the control group (P = 0.024). Furthermore, C-allele frequency was lower in the pelvic organ prolapse group than in the control group (P = 0.029). Women with the CC genotype had a 0.461-fold lower risk of developing advanced pelvic organ prolapse than women with the TT genotype (95% CI, 0.245-0.870; P = 0.017), and women with the C-allele had a 0.716-fold lower risk of developing advanced pelvic organ prolapse than women with the T-allele (95% CI, 0.527-0.973; P = 0.033).

CONCLUSIONS

These findings suggest that the poly(ADP-ribose) polymerase-1 Val762Ala polymorphism is associated with a decreased risk of advanced pelvic organ prolapse.

Alteration of apoptosis-related genes in postmenopausal women with uterine prolapse

INTRODUCTION AND HYPOTHESIS

We aimed to compare expression levels of antiapoptotic and proapoptotic genes in parametrial and vaginal tissues from postmenopausal women with and without pelvic organ prolapse (POP). We hypothesized that the expression of genes that induce apoptosis may be altered in vaginal and parametrial tissues in postmenopausal women with POP.

METHODS

Samples of vaginal and parametrial tissues were obtained from postmenopausal women with (n = 10) and without (n = 10) POP who underwent vaginal or abdominal hysterectomy. Expression levels of antiapoptotic (BCL-2, BCL-XL) and proapoptotic (BAX, BAD) genes were studied by real-time reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

Gene expression levels of BCL-2 (P < 0.001), BCL-XL (P < 0.001), BAX (p = 0.001), and BAD (p = 0.004) were all higher in vaginal tissues from the POP group compared with the non-POP group. Similarly, gene expression levels of BCL-2 (p < 0.001), BCL-XL (p < 0.001), BAX (p < 0.001), and BAD (p < 0.001) in parametrial tissues were also significantly higher in the POP group compared with the non-POP group. Additionally, expression levels of BCL-2 (p = 0.05), BCL-XL (p < 0.05), BAX (p = 0.05), and BAD (p = 0.07) in the POP group were higher in parametrial tissue than in vaginal tissue samples.

CONCLUSIONS

Antiapoptotic and proapoptotic gene expression levels differed significantly between postmenopausal women with and without POP. Bcl-2 family genes were overexpressed in the parametrium of patients with POP compared with vaginal tissue, suggesting that the processes responsible for POP have a greater effect on parametrial tissue than vaginal tissue during the development of POP.

Association between pelvic organ prolapse and stress urinary incontinence with collagen

The aim of the present study was to investigate the ultrastructure and content of collagen in uterosacral ligaments and paraurethral tissues in patients with pelvic organ prolapse (POP) and stress urinary incontinence (SUI), analyzing the association between POP and collagen dysfunction. The study comprised three groups: Control, POP and POP with SUI (n=30 per group). Histological characteristics of collagen fiber were observed and the diameters were measured using light and electron microscopy to determine the Type I and Type III collagen content of the main ligament in the urethral specimens. In the POP and POP with SUI groups, observations included diffuse atrophy of smooth muscles, active fibroblast metabolism, swollen mitochondria and visible Golgi apparatus. The collagen fibril diameters in the cardinal ligaments, uterosacral ligaments and paraurethral tissues were significantly greater in the POP and POP with SUI groups compared with those in the control group (P<0.01). In addition, the expression levels of Type I and Type III collagen were significantly lower in the POP and POP with SUI groups when compared with the control group (P<0.01). In the POP with SUI group, pelvic tissues were frail, resulting in smooth muscle bundles comminuting and arranging in a disorganized pattern. Fibroblast and myoblast metabolisms were active and new microvascular cells were weak. However, the collagen fibril diameter increased. Thus, collagen and ultrastructural changes in the pelvic floor may be associated with the development of POP and SUI.

Association between susceptibility to advanced pelvic organ prolapse and glutathione S-transferase P1 Ile105Val polymorphism

OBJECTIVE

Oxidative stress is associated with the pathogenesis of pelvic organ prolapse (POP). Because glutathione S-transferases (GSTs) are the major detoxification enzymes which protect cells against oxidative stress, genetic variations in the GST gene may modulate the risk of POP. This study aimed to determine the association between advanced POP and the polymorphisms of GSTM1, GSTT1 and GSTP1 (rs1695).

STUDY DESIGN

This is a hospital-based case-control study. The POP group consisted of 189 women diagnosed with POP stage III or IV, and the control group consisted of 156 postmenopausal women with POP stage 0 or I. The GSTM1 and GSTT1 null mutations were detected by multiplex PCR, and the GSTP1 Ile105Val polymorphism was genotyped by real-time PCR analysis using a TaqMan assay.

RESULTS

There was no significant association between the GSTM1 and GSTT1 null mutations and advanced POP (p>0.05). The distribution of the GSTP1 Ile105Val genotypes, however, was significantly different between the POP and control groups (AA/AG/GG rates=74.1%/25.9%/0% vs. 64.1%/32.1%/3.8%, p=0.008), and the G allele frequency was significantly lower in the POP group than in the control group (13.0% vs. 19.9%, p=0.014). Women with the non-AA genotype had a 0.63-fold lower risk of developing advanced POP than women with the AA genotype (95% CI, 0.39-0.99), and women with the G allele had a 0.60-fold lower risk of advanced POP than women with the A allele (95% CI, 0.40-0.90).

CONCLUSIONS

The GSTP1 Ile105Val polymorphism is a protective factor against advanced POP.

Estrogen-related genome-based expression profiling study of uterosacral ligaments in women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The aim of the study was to identify the differential expression of estrogen-related genes that may be involved in the menopause and pelvic organ prolapse (POP) using microarray analysis.

METHODS

An age, parity, and menopausal status-matched case-control study with 12 POP patients and 5 non-POP patients was carried out. The study was conducted from January to December 2010 at Yonsei University, Severance Hospital. We examined microarray gene expression profiles in uterosacral ligaments (USLs) from POP and non-POP patients. Total RNA was extracted from USL samples to generate labeled cDNA, which was hybridized to microarrays and analyzed for the expression of 44,049 genes. We identified differentially expressed genes and performed functional clustering. After clustering, we focused on transcriptional response and signal transduction gene clusters, which are associated with estrogen, and then validated the changes of gene expression levels observed with the microarray analysis using quantitative polymerase chain reaction (qPCR).

RESULTS

The data from the microarray analysis using more than a 1.5-fold change with p value <0.05 resulted in 143 upregulated genes and 87 downregulated genes. Of 59 genes identified to be associated with signal transduction and transcription, 4 genes were chosen for qPCR that have been classified to be associated with estrogen. We found that estrogen receptor-related receptor-α (ERRα) was downregulated and that the expression of death-associated protein kinase 2 (DAPK 2), signal-transducing adaptor protein-2 (STAP-2), and interleukin (IL)-15 were upregulated.

CONCLUSIONS

We found four differentially expressed genes by microarray analysis that may account for the way in which changes in estrogen level affect POP pathophysiology.

Involvement of oxidative stress and mitochondrial apoptosis in the pathogenesis of pelvic organ prolapse

PURPOSE

Biomechanical weakness of the pelvic supportive structures has been proposed to be a cause of pelvic organ prolapse. However, the molecular mechanism involved in these changes is not completely understood. In this investigation we evaluated oxidative stress biomarkers in the uterosacral ligaments of women with pelvic organ prolapse and compared them with those of women with normal support. In addition, mitochondrial apoptosis was examined.

MATERIALS AND METHODS

Samples were collected from 26 women with advanced stage pelvic organ prolapse and 29 age matched controls. The expression levels of 8-OHdG and 4-hydroxy-2-nonenal in the uterosacral ligaments were measured using immunohistochemistry. To assess mitochondrial apoptosis we performed TUNEL assay, immunohistochemistry for cleaved caspase-3 and cytochrome c, and Western blot analyses for cleaved caspase-3 and caspase-9.

RESULTS

The mean percentage of cells immunopositive for 8-OHdG, 4-hydroxy-2-nonenal, TUNEL, cleaved caspase-3 and cytochrome c in the uterosacral ligaments was significantly higher in patients with pelvic organ prolapse than in controls. Similarly, Western blot analysis revealed increased expression of cleaved caspase-3 and caspase-9 in patients with pelvic organ prolapse. Correlation analyses revealed significant positive correlations between the percentage of cells immunopositive for 8-OHdG or 4-hydroxy-2-nonenal and markers of mitochondrial apoptosis. Analyzing by pelvic organ prolapse quantification system stage according to C point, the mean percentage of cells immunopositive for 8-OHdG, 4-hydroxy-2-nonenal and cytochrome c was significantly higher in patients with pelvic organ prolapse compared to controls, regardless of stage. However, the mean percentage of TUNEL and cleaved caspase-3 positive cells was significantly higher only in patients with stage III or IV pelvic organ prolapse.

CONCLUSIONS

Oxidative stress and increased mitochondrial apoptosis may contribute to the pathological process of pelvic organ prolapse.

Tissue composition of the vaginal wall in women with pelvic organ prolapse

BACKGROUND/AIMS

To determine the composition of the vaginal wall and to explore the connective tissue layer, muscularis and basement membrane in relation to the pathogenesis of pelvic organ prolapse (POP).

METHODS

We performed a histopathological study with respect to the composition of the vaginal wall of 33 patients and 9 controls. Tissue samples from the vaginal wall were analysed for collagens II and IV, desmin, elastin, fibronectin, smooth muscle actin (SMA) and transforming growth factor (TGF)-β1 using (immuno)histochemistry. Morphometric analyses were also performed.

RESULTS

Morphometric characteristics and expression of SMA, TGF-β1, elastin and collagen II were significantly altered in women with POP.

CONCLUSION

Our results suggest that there could be an altered tissue composition of the vaginal wall in women with POP. SMA expression could play a role in the pathogenesis of POP. The alterations in elastin and TGF-β1 expression are likely a result of POP.

TGF-beta 1 is a potential regulator of vaginal tropoelastin production

INTRODUCTION AND HYPOTHESIS

Our aims were to correlate transforming growth factor (TGF)-β1 and elastin mRNA expression in the vagina of women and to measure the effects of TGF-β1 on vaginal smooth muscle cell (SMC) proliferation and tropoelastin production.

METHODS

Vaginal walls were sampled in women (n = 20). TGF-β1 and elastin mRNA expression was assessed by RT-PCR. SMC cultures were performed from vaginal wall biopsies. SMC were incubated with TGF-β1, and cell proliferation was assessed by MTT-assay. Tropoelastin production was measured by the Fastin Elastin Assay.

RESULTS

There was a significant positive correlation between TGF-β1 and elastin mRNA (r = 0.784, P < 0.01). SMC proliferation was significantly increased by 10 ng/mL TGF-β1 [relative cell number, mean ± SD, 198% ± 32% of control (P = 0.01)]. Tropoelastin production was significantly increased by TGF-β1 [mean ± SD, 645% ± 180% of control (P = 0.01)].

CONCLUSIONS

There is a positive correlation between TGF-β1 and elastin mRNA expression in the vaginal wall. In vitro, TGF-β1 increases vaginal tropoelastin production in vaginal SMC.

Expression of apoptotic factors in vaginal tissues from women with urogenital prolapse

AIMS

Increased apoptotic activity in pelvic tissues may contribute to development of pelvic floor disorders. We evaluated expression of apoptotic factors (Bcl-2 family) in vaginal tissues from women with pelvic organ prolapse (POP) and how these factors correlate with severity of prolapse.

METHODS

mRNA and protein expression of anti-apoptotic and pro-apoptotic factors in vaginal tissues from subjects and controls were determined by real-time PCR and Western blot. Severity of prolapse was staged using POP-Q criteria.

RESULTS

Differential expression of Bcl-2 family factors was observed in protein rather than in gene expression. During the secretory phase, the anti-apoptotic (Bcl-2, Bcl-xl) and pro-apoptotic protein (Bax) were upregulated in controls compared to cases (P < 0.05). The ratios of Bcl-2/Bax and Bcl-2/Bad, which determine cellular sensitivity to induction of apoptosis, were higher in controls versus cases. Higher ratios indicate reduced cellular sensitivity to apoptosis. Protein expression of Bax and Bad was higher in women with severe compared to mild prolapse (P < 0.05).

CONCLUSION

Increased expression of Bad, Bax, and decreased ratios of Bcl-2/Bax, Bcl-2/Bad suggest increased apoptotic activity or sensitivity to induction of apoptosis in vaginal tissues of women with POP.

[Connective tissue and prolapse genesis]

The pathophysiology of pelvic floor disorders still remains not well understood. Increasing age as well as vaginal multiparity are the main commonly accepted factors. The hypothesis of a defect of connective tissues of the pelvic floor with aging due to collagen deficiency and/or elastic fiber degradation is often highlighted. The issue of a potential protective role of HRT is also discussed although the recent results from the WHI would suggest a negative impact of HRT on urinary incontinence, especially when HRT is initiated in elderly women, far from the menopause. Nevertheless, environmental factors cannot explain the full pathogenesis of pelvic organ prolapse (POP) and the contribution of genetic factors to the development of pelvic floor disorders is widely recognized. Support for a genetic influence on POP derives from reports suggesting that heritability is a strong contributing factor and a familial history of POP is considered as a classical risk factor. However, the characterization of the underlying molecular mechanisms remains limited, since POP may be considered the end result of a multifactorial process leading to destruction of vaginal wall connective tissue. Experimental studies in mice with null mutations in the genes encoding different putative factors involved in elastic fibers remodeling and homeostasis are crucial in the understanding of the pathogenesis of POP. Mice with null mutation in the gene encoding lysyl oxidase-like 1 (LOXL1) or fibulin-5, demonstrate signs of elastinopathy including the development of a POP in the postpartum. Likewise, homeobox genes such as HOXA11, which are essential in the embryonic development of the urogenital tract might also be involved in the pathogenesis of POP. The better understanding of the underlying determinants of pelvic floor disorders with a special focus on genetic factors may offer new therapeutic strategies, in addition to or replacement of surgical procedures.

Differential expression of smooth muscle regulatory proteins in the uterosacral ligaments of women with uterine prolapse

OBJECTIVE

To compare smooth muscle regulatory protein expression in the uterosacral ligament (USL) of women with and without uterine prolapse.

STUDY DESIGN

USLs ligament were sampled in women with (n = 9) or without (n = 9) uterine prolapse. Caldesmon, smooth muscle actin (SMA), myosin heavy chain, and zinc finger protein messenger RNA expression was assessed by quantitative real-time polymerase chain reaction. Immunohistochemistry and digital image analysis were used to determine protein expression.

RESULTS

Caldesmon messenger RNA expression and the ratio of caldesmon-SMA messenger RNA expression was significantly increased in the USL from women with uterine prolapse compared with women without prolapse (caldesmon mean +/- standard deviation messenger RNA, 0.81 +/- 0.46 vs 0.39 +/- 0.16; P = .01 and caldesmon-SMA messenger RNA ratio, mean +/- standard deviation, 0.11 +/- 0.04 vs 0.07 +/- 0.02; P = .01). In addition, the ratio of caldesmon-SMA staining was significantly increased in women with uterine prolapse compared with women without prolapse (mean +/- standard deviation, 0.44 +/- 0.28 vs 0.28 +/- 0.16; P = .03).

CONCLUSION

Uterine prolapse is associated with an increased ratio of caldesmon-SMA actin expression.

HOXA11 promotes fibroblast proliferation and regulates p53 in uterosacral ligaments

The uterosacral ligaments (USLs) are key support structures of the uterus and upper vagina. Previously, we have shown that HOXA11 is necessary for the development of the USLs, is deficient in women with pelvic organ prolapse (POP) and regulates expression of extracellular matrix (ECM) proteins. Here we sought to determine if HOXA11 regulates cell proliferation in the USLs in women. Like others, we have found that, there is decreased cellularity in prolapsed USLs compared to USLs in women with normal pelvic support. We have also demonstrated that HOXA11 promotes cell proliferation in murine fibroblasts and primary human USL cells in vitro. These findings support a relationship between HOXA11 expression, rates of proliferation and phenotypic abnormalities in the USL. Based on these findings, we sought to determine if HOXA11 regulates p53, a tumor suppressor gene which controls progression through the cell cycle and regulates ECM genes. We have demonstrated that expression of HOXA11 represses expression of p53, suggesting a mechanism by which HOXA11 regulates of the morphology and integrity of the USLs. A better understanding of the influence of these genes on the homeostasis of the ECM and interactions with each other may prove beneficial in defining the underlying etiologies of the development of POP and aid in the development of new treatment options for women with this disorder.