Immunolocalization of Advanced Glycation End Products, Mitogen Activated Protein Kinases, and Transforming Growth Factor-β/Smads in Pelvic Organ Prolapse

An Improved Understanding of the Pathophysiology of Pelvic Organ Prolapse: A 3D In Vitro Model under Static and Mechanical Loading Conditions

The suboptimal outcomes of pelvic organ prolapse (POP) surgery illustrate the demand for improved therapies. However, their development is hampered by the limited knowledge on the cellular pathophysiology of POP. Current investigations, that are limited to tissues and 2D in vitro models, provide highly inconclusive results on how the extracellular matrix (ECM) metabolism and fibroblasts are affected in POP. This study uses a physiologically relevant 3D in vitro model to investigate the cellular pathophysiology of POP by determining the differences between POP and non-POP fibroblasts on ECM metabolism, proliferation, and fibroblast-to-myofibroblast (FMT) transition. This model, based on the synthetic and biomimetic polyisocyanide hydrogel, enables the incorporation of mechanical loading, which simulates the forces exerted on the pelvic floor. Under static conditions, 3D cultured POP fibroblasts are less proliferative, undergo FMT, and exhibit lower collagen and elastin contents compared to non-POP fibroblasts. However, under mechanical loading, the differences between POP and non-POP fibroblasts are less pronounced. This study contributes to the development of more comprehensive models that can accurately mimic the POP pathophysiology, which will aid in an enhanced understanding and may contribute to improved therapies in the future.

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.

A comprehensive evaluation of spontaneous pelvic organ prolapse in rhesus macaques as an ideal model for the study of human pelvic organ prolapse

Pelvic organ prolapse (POP) seriously affects a woman's quality of life, and the treatment complications are severe. Although new surgical treatments are being developed, the host tissue responses and safety need to be evaluated in preclinical trials. However, there is a lack of suitable animal models, as most quadrupeds exhibit different structural and pathological changes. In this study, 72 elderly rhesus macaques (Macaca mulatta) were physically examined, and the incidence of spontaneous POP was similar to that in humans. The vaginal wall from five control monkeys and four monkeys with POP were selected for further analysis. Verhoeff-van Gieson staining showed that elastin content decreased significantly in monkeys with POP compared with control samples. Immunohistological staining revealed that the smooth muscle bundles in monkey POP appeared disorganized, and the number of large muscle bundles decreased significantly. The collagen I/III ratio in monkey POP also significantly decreased, as revealed by Sirius Red staining. These histological and biochemical changes in monkeys with POP were similar to those in humans with POP. Moreover, we generated a single-cell transcriptomic atlas of the prolapsed monkey vagina. Cross-species analysis between humans and monkeys revealed a comparable cellular composition. Notably, a differential gene expression analysis determined that dysregulation of the extracellular matrix and an immune disorder were the conserved molecular mechanisms. The interplay between fibroblasts and macrophages contributed to human and monkey POP. Overall, this study represents a comprehensive evaluation of spontaneous POP in rhesus macaques and demonstrates that monkeys are a suitable animal model for POP research.

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.

PPAR-Gamma Orchestrates EMT, AGE, and Cellular Senescence Pathways in Colonic Epithelium and Restrains the Progression of IBDs

Intestinal fibrosis, the most common complication of inflammatory bowel disease (IBD), is characterized by an uncontrolled deposition of extracellular matrix proteins leading to complications resolvable only with surgery. Transforming growth factor is the key player in the epithelial-mesenchymal transition (EMT) and fibrogenesis process, and some molecules modulating its activity, including peroxisome proliferator-activated receptor (PPAR)-γ and its agonists, exert a promising antifibrotic action. The purpose of this study is to evaluate the contribution of signaling other than EMT, such as the AGE/RAGE (advanced glycation end products/receptor of AGEs) and the senescence pathways, in the etiopathogenesis of IBD. We used human biopsies from control and IBD patients, and we used a mouse model of colitis induced by dextran-sodium-sulfate (DSS), without/with treatments with GED (PPAR-gamma-agonist), or 5-aminosalicylic acid (5-ASA), a reference drug for IBD treatment. In patients, we found an increase in EMT markers, AGE/RAGE, and senescence signaling activation compared to controls. Consistently, we found the overexpression of the same pathways in DSS-treated mice. Surprisingly, the GED reduced all the pro-fibrotic pathways, in some circumstances more efficiently than 5-ASA. Results suggest that IBD patients could benefit from a combined pharmacological treatment targeting simultaneously different pathways involved in pro-fibrotic signals. In this scenario, PPAR-gamma activation could be a suitable strategy to alleviate the signs and symptoms of IBD and also its progression.

Molecular Landscape of Pelvic Organ Prolapse Provides Insights into Disease Etiology

Pelvic organ prolapse (POP) represents a major health care burden in women, but its underlying pathophysiological mechanisms have not been elucidated. We first used a case-control design to perform an exome chip study in 526 women with POP and 960 control women to identify single nucleotide variants (SNVs) associated with the disease. We then integrated the functional interactions between the POP candidate proteins derived from the exome chip study and other POP candidate molecules into a molecular landscape. We found significant associations between POP and SNVs in 54 genes. The proteins encoded by 26 of these genes fit into the molecular landscape, together with 43 other POP candidate molecules. The POP landscape is located in and around epithelial cells and fibroblasts of the urogenital tract and harbors four interacting biological processes-epithelial-mesenchymal transition, immune response, modulation of the extracellular matrix, and fibroblast function-that are regulated by sex hormones and TGFB1. Our findings were corroborated by enrichment analyses of differential gene expression data from an independent POP cohort. Lastly, based on the landscape and using vaginal fibroblasts from women with POP, we predicted and showed that metformin alters gene expression in these fibroblasts in a beneficial direction. In conclusion, our integrated molecular landscape of POP provides insights into the biological processes underlying the disease and clues towards novel treatments.

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.

Is there an association between pelvic organ prolapse and oxidative stress? A systematic review

Introduction and hypothesis

The pathophysiology of pelvic organ prolapse (POP) has not been fully elucidated, although accumulating evidence suggests that oxidative stress is involved. The present systematic review comprehensively discusses this topic.

Methods

The PubMed/Medline, Scopus, and Web of Science databases were searched for relevant studies published up to May 2021. This systematic review was registered in the PROSPERO database (registration number CRD42021242240). Two independent researchers screened and selected articles that fulfilled predefined inclusion criteria, performed a quality assessment, and extracted the relevant data. Of 901 original articles retrieved, 8 fulfilled the selection criteria and were included in the review.

Results

Elevated levels of markers of oxidative stress, such as advanced glycation end products, hydroxynonenal and hydroxydeoxyguanosine, were found in various parts of the pelvic floor of patients with POP. Accordingly, the levels of glutathione peroxidase and superoxide dismutase, known as major antioxidant enzymes, were reduced, compared to those in healthy controls. Levels of two other markers (mitofusin 2 and nuclear factor erythroid derived 2) also support hypotheses suggesting the involvement of oxidative stress in POP.

Conclusions

In the literature available, an association between oxidative stress and pelvic organ prolapse was confirmed.

The antiinflammatory and antifibrotic effect of olive phenols and Lactiplantibacillus plantarum IMC513 in dextran sodium sulfate-induced chronic colitis

OBJECTIVES

After a chronic intestinal injury, several intestinal cells switch their phenotype to activated myofibroblasts, which in turn release an abnormal amount of extracellular matrix proteins, leading to the onset of the fibrotic process. To date, no resolutive pharmacological treatments are available, and the identification of new therapeutic approaches represents a crucial goal to achieve. The onset, maintenance, and progression of inflammatory bowel disease are related to abnormal intestinal immune responses to environmental factors, including diet and intestinal microflora components. This study aimed to evaluate the potential antiinflammatory and antifibrotic effect of a biologically debittered olive cream and its probiotic oral administration in an experimental model of dextran sodium sulfate (DSS)-induced chronic colitis.

METHODS

Chronic colitis was induced in mice by three cycles of oral administration of 2.5% DSS (5 d of DSS followed by 7 d of tap water). Mice were randomly divided into five groups: 10 control mice fed with standard diet (SD), 20 mice receiving SD and DSS (SD+DSS), 20 mice receiving an enriched diet (ED) with olive cream and DSS (ED+DSS), 20 mice receiving SD plus probiotics (PB; Lactiplantibacillus plantarum IMC513) and DSS (SD+PB+DSS), and 20 mice receiving ED plus PB and DSS (ED+ PB+DSS). Clinical features and large bowel macroscopic, histologic, and immunohistochemical findings were evaluated.

RESULTS

The simultaneous administration of ED and PB induced a significant reduction in macroscopic and microscopic colitis scores compared with the other DSS-treated groups. In addition, ED and PB led to a significant decrease in the expression of inflammatory cytokines and profibrotic molecules.

CONCLUSIONS

The concomitant oral administration of a diet enriched with biologically debittered olive cream and a specific probiotic strain (Lactiplantibacillus plantarum IMC513) can exert synergistic antiinflammatory and antifibrotic action in DSS-induced chronic colitis. Further studies are needed to define the cellular and molecular mechanisms modulated by olive cream compounds and by Lactiplantibacillus plantarum IMC513.

Mesenchymal stem cell transplantation for vaginal repair in an ovariectomized rhesus macaque model

BACKGROUND

Current surgical therapies for pelvic organ prolapse (POP) do not repair weak vaginal tissue and just provide support; these therapies may trigger severe complications. Stem cell-based regenerative therapy, due to its ability to reconstruct damaged tissue, may be a promising therapeutic strategy for POP. The objective of this study is to evaluate whether mesenchymal stem cell (MSC) therapy can repair weak vaginal tissue in an ovariectomized rhesus macaque model.

METHODS

A bilateral ovariectomy model was established in rhesus macaques to induce menopause-related vaginal injury. Ten bilaterally ovariectomized rhesus macaques were divided into two groups (n=5/group): the saline group and the MSC group. Three months after ovariectomy, saline or MSCs were injected in situ into the injured vaginal wall. The vaginal tissue was harvested 12 weeks after injection for histological and biochemical analyses to evaluate changes of extracellular matrix, microvascular density, and smooth muscle in the vaginal tissue. Biomechanical properties of the vaginal tissue were assessed by uniaxial tensile testing. Data analysis was performed with unpaired Student's t test or Mann-Whitney.

RESULTS

Twelve weeks after MSC transplantation, histological and biochemical analyses revealed that the content of collagen I, elastin, and microvascular density in the lamina propria of the vagina increased significantly in the MSC group compared with the saline group. And the fraction of smooth muscle in the muscularis of vagina increased significantly in the MSC group. In addition, MSC transplantation improved the biomechanical properties of the vagina by enhancing the elastic modulus.

CONCLUSION

Vaginal MSC transplantation could repair the weak vaginal tissue by promoting extracellular matrix ingrowth, neovascularization, and smooth muscle formation and improve the biomechanical properties of the vagina, providing a new prospective treatment for POP.

Mechanical stress influences the morphology and function of human uterosacral ligament fibroblasts and activates the p38 MAPK pathway

Introduction and hypothesis

Pelvic organ prolapse (POP) is a common condition in older women that affects quality of life. Mechanical injury of the pelvic floor support system contributes to POP development. In our study, we aimed to examine the mechanical damage to human uterosacral ligament fibroblasts (hUSLFs) to preliminarily explore the mechanism of mechanical transduction in POP.

Methods

hUSLFs were derived from POP and non-POP patients. Mechanical stress was induced by the FX-5000 T-cell stress loading system. Student’s t-test was used for comparisons between different groups.

Results

We found that hUSLFs from POP patients were larger and longer than those from non-POP patients and exhibited cytoskeleton F-actin rearrangement. Collagen I and III expression levels were lower and matrix metalloproteinase 1 (MMP1) levels were higher in POP patients than in non-POP patients. Additionally, the apoptosis rate was significantly increased in POP patients compared to non-POP patients. After mechanical stretching, hUSLFs underwent a POP-like transformation. Cells became longer, and the cytoskeleton became thicker and rearranged. The extracellular matrix (ECM) was remodelled because of the upregulation of collagen I and III expression and downregulation of MMP1 expression. Mechanical stress also induced hUSLF apoptosis. Notably, we found that the p38 MAPK pathway was activated by mechanical stretching.

Conclusions

Mechanical stress induced morphological changes in ligament fibroblasts, leading to cytoskeleton and ECM remodelling and cell apoptosis. p38 MAPK might be involved in this process, providing novel insights into the mechanical biology of and possible therapies for this disease.

SMAD2, SMAD3 and TGF-β GENE expressions in women suffering from urge urinary incontinence and pelvic organ prolapse

We evaluated the changes in the levels of TGF-β and SMAD gene and protein expression in the uterosacral ligament (USL) of patients with concomitant pelvic organ prolapse (POP) and urgency urinary incontinence (UUI) to illuminate the pathophysiology of UUI. The TGF-β pathway is involved in collagen synthesis and degradation. The Transforming Growth Family-β (TGF-β) superfamily has essential intracellular signaling components, such as newly identified SMAD family members. We evaluated the changes in the levels of TGF-β and SMAD gene and protein expression in the USL of patients with concomitant pelvic organ prolapse (POP) and UUI. This study included 10 patients who had been diagnosed with POP and UUI in the study group and 14 asymptomatic women without complaints of POP and UUI in the control group. Biopsy samples were collected from bilateral USL tissues during vaginal or abdominal hysterectomy. Total RNA was extracted from USL tissue and analyzed by qPCR. The protein expression levels were also analyzed with ELISA. In UUI patients, SMAD3 and TGF-ß1 gene expression levels significantly decreased compared to the control patients (p = 0.008 and p = 0.006, respectively). SMAD2 mRNA levels did not differ between the study and control groups (p = 0.139). No differences was found in the levels of SMAD2, SMAD3, and TGF-ß1 protein expression between the two groups. The reduction in the gene and protein expression levels of SMAD3 and TGF-ß1 in women with UUI and lax uterosacral ligaments may indicate a causal link.Clinical trial registration: NCT04525105.

Evaluation of extracellular matrix protein expression and apoptosis in the uterosacral ligaments of patients with or without pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

This study aimed to compare the expression levels of extracellular matrix (ECM) and apoptosis proteins in the uterosacral ligament (USL) of patients with and without pelvic organ prolapse (POP).

METHODS

The USL were obtained from patients with POP-Q ≥ III (n = 35) and without POP (n = 20). Immunohistochemistry (IHC) staining and RT-qPCR were conducted to assess the protein and mRNA levels, respectively. The levels of type I collagen (COLI), type III collagen (COLIII), matrix metalloproteinase (MMP)1, MMP2, MMP9, tissue inhibitor of metalloproteinase (TIMP)1, TIMP2, estrogen receptor (ER)α, ERβ and apoptosis-related gene B cell lymphoma 2 (Bcl-2)-associated agonist of cell death (Bad) and Bcl-2-associated X (Bax) in the USL were analyzed.

RESULTS

The protein expression and mRNA levels of MMP2 and MMP9, mRNA levels of BAD and BAX, and protein expression of active cleaved-Caspase3 were significantly higher in the POP group. There were no evident differences in COLIII, MMP1 or ERβ expression at either the mRNA or protein level or in TIMP1, TIMP2 or Caspase3 by IHC between the two groups. However, obvious decreases in COLI and ERα were evident at both the mRNA and protein levels in the POP group, and the mRNA levels of TIMP1 and TIMP2 were also decreased compared to those of the control group.

CONCLUSION

ECM in the USL tissues of POP patients is remodeled compared with non-POP patients and is characterized by decreased synthesis and increased degradation of collagen; moreover, the levels of the main proteins involved in apoptosis are increased in POP tissue.

Changes in β-Catenin Expression in the Anterior Vaginal Wall Tissues of Women With Pelvic Organ Prolapse: A Potential Pathophysiological Mechanism

OBJECTIVES

The purpose of this study was to investigate the expression of β-catenin in the lamina propria of the anterior vaginal wall of women with pelvic organ prolapse (POP) compared with the expression in the controls.

METHODS

Anterior vaginal wall tissues were obtained from women undergoing POP surgery for stage 3 or greater POP (POP group, n = 30; age, 58 ± 7.839 years), with a menopause rate of 70%, and from women without POP undergoing hysterectomy for benign indications (control group, n = 30; age, 54.7 ± 7.173 years), with a menopause rate of 50%. Hematoxylin and eosin staining and Masson trichrome staining were performed on anterior vaginal wall sections. β-Catenin, p-β-catenin, glycogen synthase kinase 3β (GSK3β), p-GSK3β, collagen I, collagen III, MMP2, MMP9, TIMP2, caspase 3, proliferating cell nuclear antigen, and cyclin D1 were evaluated using immunohistochemical analysis. Lamina propria tissues were obtained for Western blot analyses.

RESULTS

Hematoxylin and eosin staining and Masson trichrome staining showed that the collagen fibers were more disorganized and fragmented in the POP group than in the control group. In the POP samples, β-catenin (mean density, POP vs control, 0.43 ± 0.13 vs 0.58 ± 0.16), p-GSK3β, collagen I, collagen III, proliferating cell nuclear antigen, and cyclin D1 were downregulated in the lamina propria, whereas in the control group, p-β-catenin, TIMP2, and caspase 3 were downregulated (P < 0.05 for all). GSK3β was not different between the 2 groups (P > 0.05).

CONCLUSION

We demonstrated that decreased β-catenin may play an important role in the onset of POP by affecting collagen anabolism.

Neurovascular alterations of muscularis propria in the human anterior vaginal wall in pelvic organ prolapse

In the pathophysiology and progression of pelvic organ prolapse (POP), it has been demonstrated that there is a reorganisation of the muscularis propria of the anterior vaginal wall due to a phenotypic smooth muscle cell to myofibroblast switch. An abnormal deposition of collagen type III seems to be influenced by the involvement of advanced glycation end‐products. The aim of the present study was to evaluate the hypothesis that this connective tissue remodelling could also be associated with neurovascular alterations of the muscularis in women with POP compared with control patients. We examined 30 women with POP and 10 control patients treated for uterine fibromatosis. Immunohistochemical analysis, using glial fibrillary acidic protein, S‐100 protein, receptor tyrosine kinase, neurofilament and α‐smooth muscle actin antibodies, was performed. S‐100, receptor tyrosine kinase and neurofilament were also evaluated using Western blot analysis. We observed a decrease in all neurovascular‐tested markers in nerve bundles, ganglia and interstitial cells of Cajal from POP samples as compared with controls. Even if the processes responsible for these morphological alterations are still not known, it is conceivable that collagen III deposition in the anterior vaginal wall affects not only the architecture of the muscle layer but could also modify the intramuscular neurovascularisation and account for an alteration of the neuromuscular plasticity of the layer.

Collagen changes in pelvic support tissues in women with pelvic organ prolapse

Pelvic organ prolapse is a group of diseases caused by weakened pelvic supportive tissue, but the pathophysiology is not completely understood. Collagen is one of the most important components of the extracellular matrix in connective tissue, as it maintains the supportive functions of the pelvic floor. Collagen I and III are two major subtypes in pelvic tissues. With conflicting results of different studies, changes of their content and ratio are still disputed. The structure of collagen fibrils of pelvic organ prolapse patients become loose, disorderly and discontinuous and become stiffer than control group. Strong mechanical stress and imbalance matrix metalloproteinases /tissue-derived inhibitors of metalloproteinases can lead to collagen anabolism abnormalities causing changes of collagen content and structure. These changes are inter-influenced and are involved by multiple signaling pathways, including TGF-β/Smad, AGE/RAGE, MAPK, PI3K/AKT, and NF-κB. Collagen changes, including content, morphologic and biomechanical changes and catabolism abnormalities, can destroy the supportive function of the pelvic floor and are closely related to the development of pelvic organ prolapse. Epidemiological data also show a genetic predisposition to collagen changes. Research about collagen changes in the pelvic floor supportive tissues is limited and controversial. Small sample sizes and different recruitment criteria, biopsy sites, and research methods make comparisons between various studies difficult. More research concerning collagen changes is needed to better understand the pathogenesis of pelvic organ prolapse.