Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina

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 rs2018736 fibulin-5 polymorphism as a determinant for pelvic organ prolapse: a case-control study

OBJECTIVE

Fibulin-5 is a connective tissue component and may play a role in pelvic organ prolapse (POP) pathogenesis. This study aimed to verify the association of the rs2018736 polymorphism of the fibulin-5 gene with POP in postmenopausal Brazilian women, and to determine the risk factors for POP.

METHOD

This observational, cross-sectional, case-control study assessed postmenopausal women with advanced POP (stages III and IV) and control women (stages 0 and I) by examination and peripheral blood sample collection. DNA sequences were analyzed by real-time reverse-transcriptase polymerase chain reaction. A logistic regression model was used with p < 0.05 for significance.

RESULTS

A total of 565 participants were evaluated (325 POP and 240 control). The homozygous C allele of rs2018736 (CC) was protective against POP (odds ratio [OR] 0.49, 95% confidence interval [CI] 0.26-0.91). Age (OR 1.09, 95% CI 1.05-1.13), number of pregnancies (OR 1.14, 95% CI 1.01-1.28), vaginal delivery (OR 5.32, 95% CI 2.58-11.01), forceps delivery (OR 3.34, 95% CI 1.72-6.47), weight of newborn (OR 1.0007, 95% CI 1.0002-1.0011), family history of POP (OR 2.35, 95% CI 1.24-4.44), hypertension (OR 1.74, 95% CI 1.01-3.00) and diabetes (OR 2.19, 95% CI 1.07-4.48)] were independent predictors for POP; cesarean (OR 0.02, 95% CI 0.005-0.09) was protective.

CONCLUSION

The rs2018736-CC genotype of the fibulin-5 gene has a protective role against POP.

Remodeling of murine vaginal smooth muscle function with reproductive age and elastic fiber disruption

Advanced maternal age during pregnancy is associated with increased risk of vaginal tearing during delivery and maladaptive postpartum healing. Although the underlying mechanisms of age-related vaginal injuries are not fully elucidated, changes in vaginal microstructure may contribute. Smooth muscle cells promote the contractile nature of the vagina and contribute to pelvic floor stability. While menopause is associated with decreased vaginal smooth muscle content, whether contractile changes occur before the onset of menopause remains unknown. Therefore, the first objective of this study was to quantify the active mechanical behavior of the murine vagina with age. Further, aging is associated with decreased vaginal elastin content. As such, the second objective was to determine if elastic fiber disruption alters vaginal contractility. Vaginal samples from mice aged 2-14 months were used in maximum contractility experiments and biaxial extension-inflation protocols. To evaluate the role of elastic fibers with age, half of the vaginal samples were randomly allocated to enzymatic elastic fiber disruption. Contractile potential decreased and vaginal material stiffness increased with age. These age-related changes in smooth muscle function may be due, in part, to changes in microstructural composition or contractile gene expression. Furthermore, elastic fiber disruption had a diminished effect on smooth muscle contractility in older mice. This suggests a decreased functional role of elastic fibers with age. Quantifying the age-dependent mechanical contribution of smooth muscle cells and elastic fibers to vaginal properties provides a first step towards better understanding how age-related changes in vaginal structure may contribute to tissue integrity and healing. STATEMENT OF SIGNIFICANCE: Advanced maternal age at the time of pregnancy is linked to increased risks of vaginal tearing during delivery, postpartum hemorrhaging, and the development of pelvic floor disorders. While the underlying causes of increased vaginal injuries with age and associated pathologies remain unclear, changes in vaginal microstructure, such as elastic fibers and smooth muscle cells, may contribute. Menopause is associated with fragmented elastic fibers and decreased smooth muscle content; however, how reproductive aging affects changes in the vaginal composition and the mechanical properties remains unknown. Quantifying the mechanical contribution of smooth muscle cells and elastic fibers to vaginal properties with age will advance understanding of the potential structural causes of age-related changes to tissue integrity and healing.

Collagen organization and structure in FLBN5-/- mice using label-free microscopy: implications for pelvic organ prolapse

Pelvic organ prolapse (POP) is a gynecological disorder described by the descent of superior pelvic organs into or out of the vagina as a consequence of disrupted muscles and tissue. A thorough understanding of the etiology of POP is limited by the availability of clinically relevant samples, restricting longitudinal POP studies on soft-tissue biomechanics and structure to POP-induced models such as fibulin-5 knockout (FBLN5-/-) mice. Despite being a principal constituent in the extracellular matrix, little is known about structural perturbations to collagen networks in the FBLN5-/- mouse cervix. We identify significantly different collagen network populations in normal and prolapsed cervical cross-sections using two label-free, nonlinear microscopy techniques. Collagen in the prolapsed mouse cervix tends to be more isotropic, and displays reduced alignment persistence via 2-D Fourier Transform analysis of images acquired using second harmonic generation microscopy. Furthermore, coherent Raman hyperspectral imaging revealed elevated disorder in the secondary structure of collagen in prolapsed tissues. Our results underscore the need for in situ multimodal monitoring of collagen organization to improve POP predictive capabilities.

Pregnancy-induced remodeling of the murine reproductive tract: a longitudinal in vivo magnetic resonance imaging study

Mammalian pregnancy requires gradual yet extreme remodeling of the reproductive organs to support the growth of the embryos and their birth. After delivery, the reproductive organs return to their non-pregnant state. As pregnancy has traditionally been understudied, there are many unknowns pertaining to the mechanisms behind this remarkable remodeling and repair process which, when not successful, can lead to pregnancy-related complications such as maternal trauma, pre-term birth, and pelvic floor disorders. This study presents the first longitudinal imaging data that focuses on revealing anatomical alterations of the vagina, cervix, and uterine horns during pregnancy and postpartum using the mouse model. By utilizing advanced magnetic resonance imaging (MRI) technology, T1-weighted and T2-weighted images of the reproductive organs of three mice in their in vivo environment were collected at five time points: non-pregnant, mid-pregnant (gestation day: 9-10), late pregnant (gestation day: 16-17), postpartum (24-72 h after delivery) and three weeks postpartum. Measurements of the vagina, cervix, and uterine horns were taken by analyzing MRI segmentations of these organs. The cross-sectional diameter, length, and volume of the vagina increased in late pregnancy and then returned to non-pregnant values three weeks after delivery. The cross-sectional diameter of the cervix decreased at mid-pregnancy before increasing in late pregnancy. The volume of the cervix peaked at late pregnancy before shortening by 24-72 h postpartum. As expected, the uterus increased in cross-sectional diameter, length, and volume during pregnancy. The uterine horns decreased in size postpartum, ultimately returning to their average non-pregnant size three weeks postpartum. The newly developed methods for acquiring longitudinal in vivo MRI scans of the murine reproductive system can be extended to future studies that evaluate functional and morphological alterations of this system due to pathologies, interventions, and treatments.

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.

Current practice in animal models for pelvic floor dysfunction

INTRODUCTION AND HYPOTHESIS

The objective was to explore the current practice of using animal models for female pelvic floor dysfunction (PFD).

METHODS

By applying PFD and animal models as the keywords, we made a computerized search using PubMed, Ovid-Medline and Ovid-Embase from 2000 to 2022. The publications on the construction and application of animal models for PFD were included, and the results are presented in narrative text.

RESULTS

Studies on PFD primarily use rodents, large quadrupeds, and nonhuman primates (NHPs). NHPs are closest to humans in anatomy and biomechanics of the pelvic floor, followed by large quadrupeds and rodents. Rodents are more suitable for studying molecular mechanism, histopathology of PFD, and mesh immune rejection. Large quadrupeds are adaptable to the study of pelvic floor biomechanics and the development of new surgical instruments for PFD. NHPs are suitable for studying the occurrence and pathogenesis of pelvic organ prolapse. Among modeling methods, violent destruction of pelvic floor muscles, regulation of hormone levels, and denervation were used to simulate the occurrence of PFD. Gene knockout can be used to study both the pathogenesis of PFD and the efficacy of treatments. Other methods such as abdominal wall defect, vaginal defect, and in vitro organ bath system are more frequently used to observe wound healing after surgery and to verify the efficacy of treatments.

CONCLUSIONS

The rat is currently the most applicable animal type for numerous modeling methods. Vaginal dilation is the most widely used modeling method for research on the pathogenesis, pathological changes, and treatment of PFD.

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.

Multiparity and Aging Impact Chondrogenic and Osteogenic Potential at Symphyseal Enthesis: New Insights into Interpubic Joint Remodeling

Pregnancy and childbirth cause adaptations to the birth canal to allow for delivery and fast recovery. To accommodate delivery through the birth canal, the pubic symphysis undergoes changes that lead to the interpubic ligament (IpL) and enthesis formation in primiparous mice. However, successive deliveries influence joint recovery. We aimed to understand tissue morphology and chondrogenic and osteogenic potential at symphyseal enthesis during pregnancy and postpartum in primiparous and multiparous senescent female mice. Morphological and molecular differences were found at the symphyseal enthesis among the study groups. Despite the apparent incapacity to restore cartilage in multiparous senescent animals, the symphyseal enthesis cells are active. However, these cells have reduced expression of chondrogenic and osteogenic markers and are immersed in densely packed collagen fibers contiguous to the persistent IpL. These findings may indicate alterations of key molecules in the progenitor cell population maintenance of the chondrocytic and osteogenic lineages at the symphyseal enthesis in multiparous senescent animals, possibly compromising the mouse joint histoarchitecture recovery. This sheds light on the distention of the birth canal and the pelvic floor that may play a role in pubic symphysis diastasis (PSD) and pelvic organ prolapse (POP), both in orthopedic and urogynecological practice in women.

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.

Fibulin7 aggravates calcium oxalate-induced acute kidney injury by binding to calcium oxalate crystals

Fibulin7 (Fbln7) is a matricellular protein that is structurally similar to short fibulins but does not possess elastogenic abilities. Fbln7 is localized on the cell surface of the renal tubular epithelium in the adult kidney. We previously reported that Fbln7 binds artificial calcium phosphate particles in vitro, and that heparin counteracts this binding by releasing Fbln7 from the cell surface. Fbln7 gene (Fbln7) deletion in vivo decreased interstitial fibrosis and improved renal function in a high phosphate diet-induced chronic kidney disease mouse model. However, the contribution of Fbln7 during acute injury response remains largely unknown. We hypothesized that Fbln7 serves as an exacerbating factor in acute kidney injury (AKI). We employed three AKI models in vivo and in vitro, including unilateral ureteral obstruction (UUO), cisplatin-induced AKI, and calcium oxalate (CaOx)-induced AKI. Here, we report that Fbln7KO mice were protected from kidney damage in a CaOx-induced AKI model. Using HEK293T cells, we found that Fbln7 overexpression enhanced the CaOx-induced upregulation of EGR1 and LAMB3, and that heparin treatment canceled this effect. Interestingly, the protective function observed in Fbln7KO kidneys was limited to the CaOx-induced AKI model, while Fbln7KO mice were not protected against UUO-induced renal fibrosis or cisplatin-induced renal tubular damage. Taken together, our study indicates that Fbln7 mediates the local deposition of CaOx and damages the renal tubular epithelium. Releasing Fbln7 from the cell surface via heparin/heparin derivatives or Fbln7 inhibitory antibodies may provide a general strategy to mitigate calcium crystal-induced kidney injuries.

Progesterone and its receptor signaling in cervical remodeling: Mechanisms of physiological actions and therapeutic implications

The remodeling of the cervix from a closed rigid structure to one that can open sufficiently for passage of a term infant is achieved by a complex series of molecular events that in large part are regulated by the steroid hormones progesterone and estrogen. Among hormonal influences, progesterone exerts a dominant role for most of pregnancy to initiate a loss of tissue strength yet maintain competence in a phase termed softening. Equally important are the molecular events that abrogate progesterone function in late pregnancy to allow a loss of tissue competence and strength during cervical ripening and dilation. In this review, we focus on current understanding by which progesterone receptor signaling for the majority of pregnancy followed by a loss/shift in progesterone receptor action at the end of pregnancy, collectively ensure cervical remodeling as necessary for successful parturition.

Collagen and elastic fiber remodeling in the pregnant mouse myometrium†

The myometrium undergoes progressive tissue remodeling from early to late pregnancy to support fetal growth and transitions to the contractile phase to deliver a baby at term. Much of our effort has been focused on understanding the functional role of myometrial smooth muscle cells, but the role of extracellular matrix is not clear. This study was aimed to demonstrate the expression profile of sub-sets of genes involved in the synthesis, processing, and assembly of collagen and elastic fibers, their structural remodeling during pregnancy, and hormonal regulation. Myometrial tissues were isolated from non-pregnant and pregnant mice to analyze gene expression and protein levels of components of collagen and elastic fibers. Second harmonic generation imaging was used to examine the morphology of collagen and elastic fibers. Gene and protein expressions of collagen and elastin were induced very early in pregnancy. Further, the gene expressions of some of the factors involved in the synthesis, processing, and assembly of collagen and elastic fibers were differentially expressed in the pregnant mouse myometrium. Our imaging analysis demonstrated that the collagen and elastic fibers undergo structural reorganization from early to late pregnancy. Collagen and elastin were differentially induced in response to estrogen and progesterone in the myometrium of ovariectomized mice. Collagen was induced by both estrogen and progesterone. By contrast, estrogen induced elastin, but progesterone suppressed its expression. The current study suggests progressive extracellular matrix remodeling and its potential role in the myometrial tissue mechanical function during pregnancy and parturition.

Aging of Pelvic Floor in Animal Models: A Sistematic Review of Literature on the Role of the Extracellular Matrix in the Development of Pelvic Floor Prolapse

Pelvic organ prolapse (POP) affects many women and contributes significantly to a decrease in their quality of life causing urinary and/or fecal incontinence, sexual dysfunction and dyspareunia. To better understand POP pathophysiology, prevention and treatment, many researchers resorted to evaluating animal models. Regarding this example and because POP affects principally older women, our aim was to provide an overview of literature on the possible biomechanical changes that occur in the vaginas of animal models and their supportive structures as a consequence of aging. Papers published online from 2000 until May 2021 were considered and particular attention was given to articles reporting the effects of aging on the microscopic structure of the vagina and pelvic ligaments in animal models. Most research has been conducted on rodents because their vagina structure is well characterized and similar to those of humans; furthermore, they are cost effective. The main findings concern protein structures of the connective tissue, known as elastin and collagen. We have noticed a significant discordance regarding the quantitative changes in elastin and collagen related to aging, especially because it is difficult to detect them in animal specimens. However, it seems to be clear that aging affects the qualitative properties of elastin and collagen leading to aberrant forms which may affect the elasticity and the resilience of tissues leading to pelvic floor disease. The analysis of histological changes of pelvic floor tissues related to aging underlines how these topics appear to be not fully understood so far and that more research is necessary.

International Urogynecological Consultation (IUC): pathophysiology of pelvic organ prolapse (POP)

INTRODUCTION AND HYPOTHESIS

This manuscript is the International Urogynecology Consultation (IUC) on pelvic organ prolapse (POP) chapter one, committee three, on the Pathophysiology of Pelvic Organ Prolapse assessing genetics, pregnancy, labor and delivery, age and menopause and animal models.

MATERIALS AND METHODS

An international group of urogynecologists and basic scientists performed comprehensive literature searches using pre-specified terms in selected biomedical databases to summarize the current knowledge on the pathophysiology of the development of POP, exploring specifically factors including (1) genetics, (2) pregnancy, labor and delivery, (3) age and menopause and (4) non-genetic animal models. This manuscript represents the summary of three systematic reviews with meta-analyses and one narrative review, to which a basic scientific comment on the current understanding of pathophysiologic mechanisms was added.

RESULTS

The original searches revealed over 15,000 manuscripts and abstracts which were screened, resulting in 202 manuscripts that were ultimately used. In the area of genetics the DNA polymorphisms rs2228480 at the ESR1 gene, rs12589592 at the FBLN5 gene, rs1036819 at the PGR gene and rs1800215 at the COL1A1 gene are significantly associated to POP. In the area of pregnancy, labor and delivery, the analysis confirmed a strong etiologic link between vaginal birth and symptoms of POP, with the first vaginal delivery (OR: 2.65; 95% CI: 1.81-3.88) and forceps delivery (OR: 2.51; 95% CI: 1.24-3.83) being the main determinants. Regarding age and menopause, only age was identified as a risk factor (OR : 1.102; 95% CI: 1.02-1.19) but current data do not identify postmenopausal status as being statistically associated with POP. In several animal models, there are measurable effects of pregnancy, delivery and iatrogenic menopause on the structure/function of vaginal support components, though not on the development of POP.

CONCLUSIONS

Genetics, vaginal birth and age all have a strong etiologic link to the development of POP, to which other factors may add or protect against the risk.

Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review

INTRODUCTION AND HYPOTHESIS

Mouse knockout (KO) models of pelvic organ prolapse (POP) have contributed mechanistic evidence for the role of connective tissue defects, specifically impaired elastic matrix remodeling. Our objective was to summarize what mouse KO models for POP are available and what have we learned from these mouse models about the pathophysiological mechanisms of POP development.

METHODS

We conducted a systematic review and reported narrative findings according to PRISMA guidelines. Two independent reviewers searched PubMed, Scopus and Embase for relevant manuscripts and conference abstracts for the time frame of January 1, 2000, to March 31, 2021. Conference abstracts were limited to the past 5 years.

RESULTS

The search strategy resulted in 294 total titles. We ultimately included 25 articles and an additional 11 conference abstracts. Five KO models have been studied: Loxl1, Fbln5, Fbln3, Hoxa11 and Upii-sv40t. Loxl1 and Fbln5 KO models have provided the most reliable and predictable POP phenotype. Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging. These mouse KO models have been used for a wide variety of investigations including genetic pathways involved in development of POP, biomechanical properties of the pelvic floor, elastic fiber deposition, POP therapies and the pathophysiology associated with mesh complications.

CONCLUSIONS

Mouse KO models have proved to be a valuable tool in the study of specific genes and their role in the development and progression of POP. They may be useful to study POP treatments and POP complications.

Structural, functional and molecular pathogenesis of pelvic organ prolapse in patient and Loxl1 deficient mice

Pelvic organ prolapse is a worldwide health problem to elderly women. Understanding its pathogenesis and an ideal animal model are crucial to developing promising treatments. The present study aimed to investigate new clinical significance and detailed mechanism of pelvic organ prolapse by comparing the structural, functional and molecular dysfunctions of pelvic organ prolapse in patient and Loxl1 deficient mice. Our results showed that human vagina tissues from prolapsed site showed disarranged collagen and elastic fibers compared with the non-prolapse tissue. A gene ontology (GO) analysis of differentially expressed genes revealed molecular changes mainly related to inflammatory response and extracellular matrix (ECM) organization. While the mice lacking Loxl1 developed stable POP phenotype and disordered ECM structure in histology. Such Loxl1 knockout mice exhibited a significantly urinary dysfunction and decreased mechanical properties of the pelvic floor tissues, implying that POP in human condition might be induced by progressively decreased mechanics of pelvic tissues following ECM catabolism. Similarly, we not only identified significant up-regulated ECM catabolism processes and down-regulated ECM synthesis processes, but also characterized high level of inflammatory response in vagina tissue of the Loxl1 deficient mice. Thus, all these pathological changes in the POP mice model was consistent with those of the clinical elderly patients. These findings provide new insight into remodeling of POP by LOXL1 regulation and be of great importance to develop combination treatments of ECM metabolism and inflammation regulation strategy.

Investigation of Murine Vaginal Creep Response to Altered Mechanical Loads

The vagina is a viscoelastic fibromuscular organ that provides support to the pelvic organs. The viscoelastic properties of the vagina are understudied but may be critical for pelvic stability. Most studies evaluate vaginal viscoelasticity under a single uniaxial load; however, the vagina is subjected to dynamic multiaxial loading in the body. It is unknown how varied multiaxial loading conditions affect vaginal viscoelastic behavior and which microstructural processes dictate the viscoelastic response. Therefore, the objective was to develop methods using extension-inflation protocols to quantify vaginal viscoelastic creep under various circumferential and axial loads. Then, the protocol was applied to quantify vaginal creep and collagen microstructure in the fibulin-5 wildtype and haploinsufficient vaginas. To evaluate pressure-dependent creep, the fibulin-5 wildtype and haploinsufficient vaginas (n = 7/genotype) were subjected to various constant pressures at the physiologic length for 100 s. For axial length-dependent creep, the vaginas (n = 7/genotype) were extended to various fixed axial lengths then subjected to the mean in vivo pressure for 100 s. Second-harmonic generation imaging was performed to quantify collagen fiber organization and undulation (n = 3/genotype). Increased pressure significantly increased creep strain in the wildtype, but not the haploinsufficient vagina. The axial length did not significantly affect the creep rate or strain in both genotypes. Collagen undulation varied through the depth of the subepithelium but not between genotypes. These findings suggest that the creep response to loading may vary with biological processes and pathologies, therefore, evaluating vaginal creep under various circumferential loads may be important to understand vaginal function.

Summary of Utah Project on Exfoliation Syndrome (UPEXS): using a large database to identify systemic comorbidities

The purpose of the Utah Project on Exfoliation Syndrome (UPEXS) is to identify associations between exfoliation syndrome (XFS) and other diseases that share the commonality of abnormalities in elastin and Lysyl Oxidase-Like 1 gene regulation. The UPEXS is unique because it uses the Utah Population Database, which is linked to the Utah genealogy, that contains a compilation of large pedigrees of most families in the state of Utah that go back multiple generations (3 to ≥11). The health and medical records of these family members are linked to vital records and can be used effectively in studies focused on genetic disorders like XFS, where familial clustering of a disorder is a trend. There is increasing evidence that patients with XFS have a higher risk of certain systemic disorders that reflect the systemic tissue abnormalities of XFS. Epidemiological studies focused on patients with XFS have shown that there is an increased risk of these individuals developing other pathologies that have abnormalities in extracellular matrix metabolism and repair. UPEXS has focused on suspected comorbidities that involve abnormalities in elastin maintenance, a protein that plays a role in the makeup of the extracellular matrix. In this paper, the results from the analysis of chronic obstructive pulmonary disease, inguinal hernias, pelvic organ prolapse, obstructive sleep apnoea and atrial fibrillation are summarised along with the utility of using such a large dataset.

Role of fibulin-5 insufficiency and prolapse progression on murine vaginal biomechanical function

The vagina plays a critical role in supporting the pelvic organs and loss of support leads to pelvic organ prolapse. It is unknown what microstructural changes influence prolapse progression nor how decreased elastic fibers contributes to vaginal remodeling and smooth muscle contractility. The objective for this study was to evaluate the effect of fibulin-5 haploinsufficiency, and deficiency with progressive prolapse on the biaxial contractile and biomechanical function of the murine vagina. Vaginas from wildtype (n = 13), haploinsufficient (n = 13), and deficient mice with grade 1 (n = 9) and grade 2 or 3 (n = 9) prolapse were explanted for biaxial contractile and biomechanical testing. Multiaxial histology (n = 3/group) evaluated elastic and collagen fiber microstructure. Western blotting quantified protein expression (n = 6/group). A one-way ANOVA or Kruskal-Wallis test evaluated statistical significance. Pearson's or Spearman's test determined correlations with prolapse grade. Axial contractility decreased with fibulin-5 deficiency and POP (p < 0.001), negatively correlated with prolapse grade (ρ = - 0.80; p < 0.001), and positively correlated with muscularis elastin area fraction (ρ = - 0.78; p = 0.004). Circumferential (ρ = 0.71; p < 0.001) and axial (ρ = 0.69; p < 0.001) vaginal wall stresses positively correlated with prolapse grade. These findings demonstrated that fibulin-5 deficiency and prolapse progression decreased vaginal contractility and increased vaginal wall stress. Future work is needed to better understand the processes that contribute to prolapse progression in order to guide diagnostic, preventative, and treatment strategies.

Clinical Relevance of Elastin in the Structure and Function of Skin

Elastin is the main component of elastic fibers, which provide stretch, recoil, and elasticity to the skin. Normal levels of elastic fiber production, organization, and integration with other cutaneous extracellular matrix proteins, proteoglycans, and glycosaminoglycans are integral to maintaining healthy skin structure, function, and youthful appearance. Although elastin has very low turnover, its production decreases after individuals reach maturity and it is susceptible to damage from many factors. With advancing age and exposure to environmental insults, elastic fibers degrade. This degradation contributes to the loss of the skin's structural integrity; combined with subcutaneous fat loss, this results in looser, sagging skin, causing undesirable changes in appearance. The most dramatic changes occur in chronically sun-exposed skin, which displays sharply altered amounts and arrangements of cutaneous elastic fibers, decreased fine elastic fibers in the superficial dermis connecting to the epidermis, and replacement of the normal collagen-rich superficial dermis with abnormal clumps of solar elastosis material. Disruption of elastic fiber networks also leads to undesirable characteristics in wound healing, and the worsening structure and appearance of scars and stretch marks. Identifying ways to replenish elastin and elastic fibers should improve the skin's appearance, texture, resiliency, and wound-healing capabilities. However, few therapies are capable of repairing elastic fibers or substantially reorganizing the elastin/microfibril network. This review describes the clinical relevance of elastin in the context of the structure and function of healthy and aging skin, wound healing, and scars and introduces new approaches being developed to target elastin production and elastic fiber formation.

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

INTRODUCTION AND HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Mass cytometry and transcriptomic profiling reveal body-wide pathology induced by Loxl1 deficiency

Objective

The loss of LOXL1 expression reportedly leads to the prolapse of pelvic organs or to exfoliation syndrome glaucoma. Increasing evidence suggests that LOXL1 deficiency is associated with the pathogenesis of several other diseases. However, the characterization of the systemic functions of LOXL1 is limited by the lack of relevant investigative technologies.

Materials and Methods

To determine the functions of LOXL1, a novel method for body‐wide organ transcriptome profiling, combined with single‐cell mass cytometry, was developed. A body‐wide organ transcriptomic (BOT) map was created by RNA‐Seq of tissues from 17 organs from both Loxl1 knockout (KO) and wild‐type mice.

Results

The BOT results indicated the systemic upregulation of genes encoding proteins associated with the immune response and proliferation processes in multiple tissues of KO mice, and histological and immune staining confirmed the hyperplasia and infiltration of local immune cells in the tissues of KO mice. Furthermore, mass cytometry analysis of peripheral blood samples revealed systemic immune changes in KO mice. These findings were well correlated with results obtained from cancer databases. Patients with tumours had higher Loxl1 mutation frequencies, and patients with Loxl1‐mutant tumours showed the upregulation of immune processes and cell proliferation and lower survival rates.

Conclusion

This study provides an effective strategy for the screening of gene functions in multiple organs and also illustrates the important biological roles of LOXL1 in the cells of multiple organs as well as in systemic immunity.

Elastin homeostasis is altered with pelvic organ prolapse in cultures of vaginal cells from a lysyl oxidase-like 1 knockout mouse model

Pelvic organ prolapse (POP) decreases quality of life for many women, but its pathophysiology is poorly understood. We have previously shown that Lysyl oxidase‐like 1 knockout (Loxl1 KO) mice reliably prolapse with age and increased parity, similar to women. Both this model and clinical studies also indicate that altered elastin metabolism in pelvic floor tissues plays a role in POP manifestation, although it is unknown if this is a cause or effect. Using Loxl1 KO mice, we investigated the effects of genetic absence of Loxl1, vaginal parity, and presence of POP on the expression of genes and proteins key to the production and regulation of elastic matrix. Cultured cells isolated from vaginal explants of mice were assayed with Fastin for elastic matrix, as well as RT‐PCR and Western blot for expression of genes and proteins important for elastin homeostasis. Elastin synthesis significantly decreased with absence of LOXL1 and increased with parity (p < .001), but not with POP. Cells from prolapsed mice expressed significantly decreased MMP‐2 (p < .05) and increased TIMP‐4 (p < .05). The results suggest changes to elastin structure rather than amounts in prolapsed mice as well as poor postpartum elastin turnover, resulting in accumulation of damaged elastic fibers leading to abnormal tropoelastin deposition. POP may thus, be the result of an inability to initiate the molecular mechanisms necessary to clear and replace damaged elastic matrix in pelvic floor tissues after vaginal birth.

A Non-Invasive Determination of LOXL1 and Fibulin-5 Levels in the Vaginal Secretions of Women with and Without Pelvic Organ Prolapse

OBJECTIVES

The aim of this study was to determine if lysyl oxidase-like 1 (LOXL1) and Fibulin-5 (Fib-5), two crucial proteins in the elastin metabolism pathway, are detectable in the vaginal secretions of women with and without pelvic organ prolapse (POP). We then sought to quantify levels of these proteins in relation to prolapse.

METHODS

Vaginal secretions were obtained from 48 subjects (13 (27.1%) without and 35 (72.9%) with POP-Q Stage 2-4 prolapse). Eleven (22.9%) subjects were premenopausal and 37 (77.1%) were postmenopausal. Presence of LOXL-1 and Fibulin-5 within specimens were first identified via western blotting. Enzyme-Linked Immunosorbent Assays specific for LOXL1 and Fibulin-5 were conducted to quantify total protein secretion.

RESULTS

LOXL1 was detected in 45/48 (93.8%) and Fibulin-5 was seen in 24/48 (50%) of subjects. LOXL1 values were lower in women without prolapse (13.3 ng/100 mg median, 24.4 IQR) vs. those with prolapse (26.4 ng/100 mg, 102.2 IQR). On multivariate analysis controlling for age, women with prolapse had a 544% (p=0.0042 higher LOXL1 protein level compared to those without. There was no significant differences in LOXL1 or Fibulin-5 protein detection with relation to menopausal status in bivariate analysis.

CONCLUSIONS

This is the first published report of non-invasively measuring urogenital LOXL1 and Fibulin-5. In vaginal secretions, LOXL1 protein is higher in subjects with POP than those without.

Upregulation of PTK7 and β-catenin after vaginal mechanical dilatation: an examination of fibulin-5 knockout mice

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) in women is associated with deficiency of elastic fibers, and fibulin-5 is known to be a critical protein in the synthesis of elastin. The purpose of this study is to investigate the related pathway for the synthesis of elastin via fibulin-5 using fibulin-5 knockout mice.

METHODS

Fibulin-5 knockout mice were generated using the CRISPR/Cas9 system, and vaginal dilatation was used to mimic vaginal delivery. We divided the mice into three groups: Fbln5^+/+ mice immediately after dilatation (Fbln5^+/+ day0), Fbln5^+/+ mice 3 days after dilatation (Fbln5^+/+ day3) and Fbln5^-/- mice 3 days after dilatation (Fbln5^-/- day3). Proteins related to elastogenesis in the vaginal wall were measured by liquid chromatography mass spectrometry (LC-MS/MS) analysis, and differences in the expression of these proteins between the Fbln5^-/- mice and the Fbln5^+/+ mice were analyzed using western blotting.

RESULTS

In the LC-MS/MS analysis, protein tyrosine kinase 7 (PTK7) was not detected in the Fbln5^-/- day3 group, although the expression increased by > 1.5 times between the Fbln5^+/+ day0 and day3 groups. PTK7 and β-catenin are known to act in the Wnt/β-catenin pathway, and both were upregulated after dilatation in the Fbln5^+/+ mice, though not in the Fbln5^-/- mice.

CONCLUSION

Our findings suggest that these proteins are involved in elastogenesis via fibulin-5, and the impairment of these proteins might be the underlying cause of POP manifestation.

Dysregulated assembly of elastic fibers in fibulin-5 knockout mice results in a tendon-specific increase in elastic modulus

Elastic fiber assembly is coordinated in part by fibulin-5, a matricellular protein. When fibulin-5 is not available to guide elastogenesis, elastin forms into disconnected globules instead of the dense elastic fiber core found in healthy tissues. Despite the growing evidence for a significant role of elastic fibers in tendon mechanics and the clinical relevance to cutis laxa, a human disease which can be caused by a mutation in the gene encoding fibulin-5, it is unknown how malformed elastic fibers affect tendon function. Therefore, this study investigated the effects of dysregulated elastic fiber assembly in tendons from fibulin-5 knockout mice in comparison to wild-type controls. Due to evidence for a more prominent role of elastic fibers in tendons with higher functional demands, both the energy-storing Achilles tendon and the more positional tibialis anterior tendon were evaluated. The linear modulus of knockout Achilles tendons was increased compared to controls, yet there was no discernible change in mechanical properties of the tibialis anterior tendon across genotypes. Transmission electron microscopy confirmed the presence of malformed elastic fibers in knockout tendons while no other changes to tendon composition or structure were found. The mechanism behind the increase in linear modulus in fibulin-5 knockout Achilles tendons may be greater collagen engagement due to decreased regulation of strain-induced structural reorganization. These findings support the theory of a significant, functionally distinct role of elastic fibers in tendon mechanics.

Pelvic Organ Prolapse: A Review of In Vitro Testing of Pelvic Support Mechanisms

Background: Pelvic organ prolapse (POP) affects a significant portion of the female population, impacting quality of life and often requiring intervention. The exact cause of prolapse is unknown.

Methods: We review some of the current research that focuses on defining the elements involved in POP, with a focus on in vitro testing.

Results: Treatment for POP, ranging from physical therapy or pessary use to more invasive surgery, has varying success rates. This variation is, in part, because the pathophysiology of pelvic floor support—and thus dysfunction—is incompletely understood, particularly regarding the structural components and biomechanical properties of tissue. However, researchers are working to identify and quantify the structural and functional dysfunction that may lead to the development of this condition.

Conclusion: Given the limited understanding of prolapse development, more research is needed to quantify the microstructure of the pelvic organs and pelvic support structures, with and without prolapse. Identifying biomechanical properties in multiaxial configurations will improve our understanding of pelvic tissue support, as well as our ability to establish predictive models and improve clinical treatment strategies.

Differential Lysyl oxidase like 1 expression in pseudoexfoliation glaucoma is orchestrated via DNA methylation

Pseudoexfoliation syndrome (PXF) is the most common cause of secondary open angle glaucoma worldwide. Single nucleotide polymorphisms (SNPs) in the gene Lysyl oxidase like 1 (LOXL1) are strongly associated with the development of pseudoexfoliation glaucoma (PXFG). However, these SNPs are also present in 50-80% of the general population, suggestive of other factors being involved in the pathogenesis of PXFG. In this study, we aimed to investigate the influence of epigenetic regulation, specifically DNA methylation, on LOXL1 expression in PXFG using human tenons fibroblasts (HTFs), aqueous humour and serum samples from donors with and without PXFG. LOXL1 expression in HTFs was measured by qPCR and Western Blotting and LOXL1 concentration in aqueous humour was determined by ELISA. Global DNA methylation levels were quantified using an ELISA for 5-methylcytosine. MeDIP assays assessed the methylation status of the LOXL1 promoter region. Expression of methylation-associated enzymes (DNMT1, DNMT3a and MeCP2) were determined by qPCR and inhibited by 0.3 μM 5-azacytidine (5-aza). Results showed that LOXL1 expression was significantly decreased in PXFG HTFs compared with Control HTFs at gene (Fold change 0.37 ± 0.05, P < 0.01) level and showed a decrease, when measured at the protein level (Fold change 0.65 ± 0.42, P = 0.22), however this was not found to be significant. LOXL1 concentration was increased in the aqueous of PXFG patients compared with Controls (2.76 ± 0.78 vs. 1.79 ± 0.33 ng/ml, P < 0.01). Increased global methylation (56.07% ± 4.87% vs. 32.39% ± 4.29%, P < 0.01) was observed in PXFG HTFs compared with Control HTFs, as was expression of methylation-associated enzymes (DNMT1 1.58 ± 0.30, P < 0.05, DNMT3a 1.89 ± 0.24, P < 0.05, MeCP2 1.63 ± 0.30, P < 0.01). Methylation-associated enzymes were also increased when measured at protein level (DNMT1 5.70 ± 2.64, P = 0.04, DNMT3a 1.79 ± 1.55, P = 0.42, MeCP2 1.64 ± 1.33, P = 0.45). LOXL1 promoter methylation was increased in patients with PXFG compared to Control patients in both blood (3.98 ± 2.24, 2.10 ± 1.29, P < 0.05) and HTF cells (37.31 ± 22.0, 8.66 ± 10.40, P < 0.01). Treatment of PXFG HTFs with in 5-azacytidine increased LOXL1 expression when compared with untreated PXFG HTFs (Fold change 2.26 ± 0.67, P < 0.05). These data demonstrate that LOXL1 expression is altered in PXFG via DNA methylation and that reversal of these epigenetic changes may represent future potential therapeutic targets in the management of PXFG.

Role of lysyl oxidase like 1 in regulation of postpartum connective tissue metabolism in the mouse vagina†

Pelvic organ prolapse (POP) in lysyl oxidase like-1 knockout (Loxl1 KO) mice occurs primarily in parous mice and is rare in nulliparous mice. We determined the effect of Loxl1 deficiency on postpartum regulation of connective tissue metabolism genes and degradative enzyme activity in the vagina at 20 days gestation or 4 h, 48 h, 7 days, 15 days, 25 days, 7 weeks, or 12 weeks postpartum. Nulliparous Loxl1 KO and wildtype (WT) mice aged 11, 18, or 23 weeks were controls. Gene expression and enzyme activity were assessed using real-time quantitative reverse transcription PCR and fluorescein conjugated gelatin zymography, respectively. Parity, but not aging, had a significant influence on gene expression both with time postpartum and between KO and WT mice. Mmp2, Timp1, Timp2, Timp3, Timp4, Col1a1, Col3a1, Acta2, and Bmp1 were differentially expressed between KO and WT mice. Correlational analysis of gene-gene pairs revealed 10 significant differences between parous KO and WT groups, 5 of which were due to lack of co-expression of Bmp1 in KO mice. The overall enzyme activity that could be attributed to MMPs was significantly higher in WT compared to KO mice both 25 days and 12 weeks postpartum, and MMP activity was significantly lower 15 days and 25 days postpartum compared to KO nulliparous controls, but not WT. These findings suggest that Loxl1 deficiency combined with parity has a significant impact on postpartum regulation of connective tissue metabolism, particularly as it relates to co-expression of Bmp1 and altered proteolytic activity.

Recruitment of monocytes and mature macrophages in mouse pubic symphysis relaxation during pregnancy and postpartum recovery†

Appropriate remodeling of the female lower reproductive tract and pelvic floor is essential during normal mammalian pregnancy, labor, and postpartum recovery. During mouse pregnancy, in addition to reproductive tract modifications, the pubic symphysis (PS) is remodeled into a soft interpubic ligament (IpL) to provide safe delivery of the offspring and fast postpartum recovery. Although temporal changes in the phenotypes of myeloid cells, such as mononuclear phagocytes, are crucial to remodeling the lower reproductive tract organs in preparation for a safe delivery, little is known about the involvement of recruited monocytes or macrophages in mouse PS remodeling. We used combined light microscopy, electron microscopy, and qPCR analysis to investigate the profile of recruited monocytes and macrophage polarization markers in C57Bl6 mouse interpubic tissues during pregnancy (D12, D18, and D19) and early days postpartum (1 dpp and 3 dpp) to better identify their presence in proper remodeling of the mouse PS. Our morphological data show that the number of recruited monocytes is increased in interpubic tissues and that recruited monocytes differentiate into proinflammatory or anti-inflammatory macrophage phenotypes from D18 to 3 dpp, which may contribute to dynamic changes in the gene expression of specific inflammatory mediators involved in interpubic tissue remodeling at these time points. Therefore, our morphological and quantitative gene expression data suggest that both differentiated macrophages from recruited monocytes and polarized macrophages may collaborate for IpL relaxation at labor and the appropriate repair of the PS after the first pregnancy.

Oxidative Stress: A Possible Trigger for Pelvic Organ Prolapse

Pelvic organ prolapse is a frequent health problem in women, encountered worldwide, its physiopathology being still incompletely understood. The integrity of the pelvic-supportive structures is a key element that prevents the prolapse of the pelvic organs. Numerous researchers have underlined the role of connective tissue molecular changes in the pathogenesis of pelvic organ prolapse and have raised the attention upon oxidative stress as an important element involved in its appearance. The advancements made over the years in terms of molecular biology have allowed researchers to investigate how the constituent elements of the pelvic-supportive structures react in conditions of oxidative stress. The purpose of this paper is to underline the importance of oxidative stress in the pathogenesis of pelvic organ prolapse, as well as to highlight the main oxidative stress molecular changes that appear at the level of the pelvic-supportive structures. Sustained mechanical stress is proven to be a key factor in the appearance of pelvic organ prolapse, correlating with increased levels of free radicals production and mitochondrial-induced fibroblasts apoptosis, the rate of cellular apoptosis depending on the intensity of the mechanical stress, and the period of time the mechanical stress is applied. Oxidative stress hinders normal cellular signaling pathways, as well as different important cellular components like proteins, lipids, and cellular DNA, therefore significantly interfering with the process of collagen and elastin synthesis.

Evaluation of the fibulin 5 gene polymorphism as a factor related to the occurrence of pelvic organ prolapse

OBJECTIVE Pelvic organ prolapse (POP) is a very frequent situation in our population that may lead to a significant decrease in patients' quality of life. Currently, we are looking for predictive factors for the development of POPs; thus, this study seeks to evaluate whether the Fibulin 5 polymorphism (FBLN5) is associated with the occurrence of POP. METHODS This is a cohort study with postmenopausal women who were divided into groups by POP stage: POP stages 0 and I (control group) and POP stages III and IV (case group). Subsequently, analyses of genetic polymorphisms of FBLN5 were performed using the Restriction Fragment Length Polymorphism (RFLP) technique. RESULTS A total of 292 women were included in the study. Pregnancy, parity and vaginal delivery in the patients, as well as in data described in the literature, were related to the occurrence of POP in the univariate analysis. However, after binary logistic regression, home birth and age remained independent risk factors for POP. We found no association between the FBLN5 polymorphism and the occurrence of POP (p = 0.371). CONCLUSION There was no association between the FBLN5 polymorphism and the occurrence of POP in Brazilian women.

Protease Inhibition Improves Healing of The Vaginal Wall after Obstetrical Injury: Results from a Preclinical Animal Model

Vaginal delivery with obstetrical trauma is a risk factor for pelvic organ prolapse later in life. Loss of fibulin-5 (FBLN5), an elastogenesis-promoting cellular matrix protein, results in prolapse in mice. Here, we evaluated effects of pregnancy, parturition, and obstetrical injury on FBLN5 content, elastic fibers, biomechanics, and histomorphology of the vaginal wall in rats. Further, we analyzed the effects of actinonin, a protease inhibitor, on obstetrical injury of the vaginal wall. Vaginal FBLN5 decreased significantly in pregnancy, and injury resulted in further downregulation. Stiffness of the vaginal wall decreased 82% in pregnant rats and 74% (p = 0.019) with injury relative to uninjured vaginal delivery controls at 3d. Actinonin ameliorated loss of FBLN5, rescued injury-induced loss of elastic fibers and biomechanical properties after parturition, and reduced the area of injury 10-fold. We conclude that pregnancy and parturition have a profound impact on vaginal FBLN5 and biomechanics of the vaginal wall. Further, obstetrical injury has significant deleterious impact on recovery of the vaginal wall from pregnancy. Actinonin, a non-specific matrix metalloprotease inhibitor, improved recovery of the parturient vaginal wall after obstetrical injury.

Shear Wave Elastography to Assess Perineal Body Stiffness During Labor

OBJECTIVES

The objective of this study was to evaluate perineal body stiffness intrapartum using shear wave elastography ultrasound and to study its association with maternal and labor characteristics.

METHODS

This was a prospective observational study. Pregnant women with term pregnancy who had been admitted for labor management were recruited into the study. Transperineal shear wave elastography of perineal body was performed. Maternal and labor data were retrieved from electronic medical charts.

RESULTS

Thirty-two patients' data were available for analysis. Mean (SD) melastography modulus was 15.33 (5.49). While comparing the mean elastography modulus across maternal and labor characteristics, the difference was statistically different between parity, cervical dilation, and perineal laceration presence groups (P < 0.05). The mean of elastography modulus of primiparous women with cervical dilation less than 3 cm was 21.47 kPa, whereas that of multiparous women was 13.17 kPa (P = 0.0511). Perineal laceration was more prevalent in women with stiffer perineal body. The risk of having perineal laceration compared with no perineal laceration was 29.1% higher for each additional unit increase in perineal body elastography modulus (odds ratio, 0.709; 95% confidence interval, 0.507-0.992).

CONCLUSIONS

Shear wave elastography can be used to quantify perineal body stiffness. Primiparous women in early stages of labor have stiffer perineal body than multiparous women in any stage of labor and primiparous women in late stage of labor.

Lysyl Oxidase Like 1: Biological roles and regulation

Lysyl Oxidase Like 1 (LOXL1) is a gene that encodes for the LOXL1 enzyme. This enzyme is required for elastin biogenesis and collagen cross-linking, polymerising tropoelastin monomers into elastin polymers. Its main role is in elastin homeostasis and matrix remodelling during injury, fibrosis and cancer development. Because of its vast range of biological functions, abnormalities in LOXL1 underlie many disease processes. Decreased LOXL1 expression is observed in disorders of elastin such as Cutis Laxa and increased expression is reported in fibrotic disease such as Idiopathic Pulmonary Fibrosis. LOXL1 is also downregulated in the lamina cribrosa in pseudoexfoliation glaucoma and genetic variants in the LOXL1 gene have been linked with an increased risk of developing pseudoexfoliation glaucoma and pseudoexfoliation syndrome. However the two major risk alleles are reversed in certain ethnic groups and are present in a large proportion of the normal population, implying complex genetic and environmental regulation is involved in disease pathogenesis. It also appears that the non-coding variants in intron 1 of LOXL1 may be involved in the regulation of LOXL1 expression. Gene alteration may occur via a number of epigenetic and post translational mechanisms such as DNA methylation, long non-coding RNAs and microRNAs. These may represent future therapeutic targets for disease. Environmental factors such as hypoxia, oxidative stress and ultraviolet radiation exposure alter LOXL1 expression, and it is likely a combination of these genetic and environmental factors that influence disease development and progression. In this review, we discuss LOXL1 properties, biological roles and regulation in detail with a focus on pseudoexfoliation syndrome and glaucoma.

Effect of Protease Inhibitors in Healing of the Vaginal Wall

Impaired elastogenesis and increased degradation of elastic fibers has been implicated in the pathogenesis of pelvic organ prolapse. Loss of the elastogenic organizer, fibulin-5 (FBLN5), leads to pelvic organ prolapse in mice. The objective of this study was to investigate the regulation of FBLN5 after surgical injury of the vaginal wall using the rat as a preclinical animal model. Both endogenous and recombinant FBLN5 were degraded after surgical injury. Estrogen did not alter the dramatic loss of vaginal FBLN5 in the acute phase after injury (12–48 h), but resulted in rescue of the poor recovery of FBLN5 levels in the late phase (7 d) of healing in ovariectomized animals. In contrast with estrogen, the general MMP inhibitor, actinonin, abrogated injury-induced degradation of FBLN5 significantly. Further, actinonin rescued the negative effects of injury on biomechanics, histomorphology, and elastic fibers. Control of excessive matrix degradation by local application of actinonin at the time of surgery may lead to improved elastic fiber regeneration and wound healing, thereby potentially enhancing pelvic floor recovery after reconstructive surgery for prolapse.

Managing female pelvic floor disorders: a medical device review and appraisal

Pelvic floor disorders (PFDs) will affect most women during their lifetime. Sequelae such as pelvic organ prolapse, stress urinary incontinence, chronic pain and dyspareunia significantly impact overall quality of life. Interventions to manage or eliminate symptoms from PFDs aim to restore support of the pelvic floor. Pessaries have been used to mechanically counteract PFDs for thousands of years, but do not offer a cure. By contrast, surgically implanted grafts or mesh offer patients a more permanent resolution but have been in wide use within the pelvis for less than 30 years. In this perspective review, we provide an overview of the main theories underpinning PFD pathogenesis and the animal models used to investigate it. We highlight the clinical outcomes of mesh and grafts before exploring studies performed to elucidate tissue level effects and bioengineering considerations. Considering recent turmoil surrounding transvaginal mesh, the role of pessaries, an impermanent method, is examined as a means to address patients with PFDs.

Alterations of elastin in female reproductive tissues arising from advancing parity

Female reproductive tissues undergo significant alterations during pregnancy, which may compromise the structural integrity of extracellular matrix proteins. Here, we report on modifications of elastic fibers, which are primarily composed of elastin and believed to provide a scaffold to the reproductive tissues, due to parity and parturition. Elastic fibers from the upper vaginal wall of virgin Sprague Dawley rats were investigated and compared to rats having undergone one, three, or more than five pregnancies. Optical microscopy was used to study fiber level changes. Mass spectrometry, ¹³C and ²H NMR, was applied to study alterations of elastin from the uterine horns. Spectrophotometry was used to measure matrix metalloproteinases-2,9 and tissue inhibitor of metalloproteinase-1 concentration changes in the uterine horns. Elastic fibers were found to exhibit increase in tortuosity and fragmentation with increased pregnancies. Surprisingly, secondary structure, dynamics, and crosslinking of elastin from multiparous cohorts appear similar to healthy mammalian tissues, despite fragmentation observed at the fiber level. In contrast, elastic fibers from virgin and single pregnancy cohorts are less fragmented and comprised of elastin exhibiting structure and dynamics distinguishable from multiparous groups, with reduced crosslinking. These alterations were correlated to matrix metalloproteinases-2,9 and tissue inhibitor of metalloproteinase-1 concentrations. This work indicates that fiber level alterations resulting from pregnancy and/or parturition, such as fragmentation, rather than secondary structure (e.g. elastin crosslinking density), appear to govern scaffolding characteristics in the female reproductive tissues.

The effect of consecutive pregnancies on the ovine pelvic soft tissues: Link between biomechanical and histological components

BACKGROUND

Pelvic organ prolapse, various types of incontinence (urinary incontinence, defecatory dysfunction), chronic cystourethritis, and sexual dysfunctions remain between the most common disorders in urogynecology. Currently, it is believed that the nature and number of births plays a major role in their development. Moreover, after these events, pelvic floor tissues may not recover to their original statuses. The close anatomical relationship among the vaginal wall, bladder and rectum often contribute to the emergence of anatomical-functional failure of adjacent organs and systems.

BASIC PROCEDURES

The aim of this study was to investigate the effect of consecutive pregnancies on pelvic floor soft tissues, conducting biomechanical and histological analysis. Fifteen Swifter ewes: virgins, parous and pregnant were used. Samples, for uniaxial tension tests and histological analysis, were cut out from fresh tissue. A description of the mechanical properties of native tissue was obtained from the stress-strain curve. Histological samples were stained with Miller's Elastica staining and analyzed using ImageJ software. Collagen, elastin, and smooth muscle contents (%) were analyzed along the full wall thickness of the selected organs. The links between mechanical properties of the soft tissues and histological parameters were analyzed.

MAIN FINDINGS

Mechanically, vaginal wall tissue and cervix of pregnant sheep were more compliant. In contrast, bladder and rectum became stiffer and had the highest total collagen content. Parous sheep rectum and bladder were stiffer, compared to virgin sheep.

PRINCIPAL CONCLUSIONS

Tensile strength appears to be linked to total collagen content. Elastin and smooth muscle show a direct influence on tissue compliance.

Effects of elastase digestion on the murine vaginal wall biaxial mechanical response

Although the underlying mechanisms of pelvic organ prolapse (POP) remain unknown, disruption of elastic fiber metabolism within the vaginal wall extracellular matrix has been highly implicated. It has been hypothesized that elastic fiber fragmentation correlates to decreased structural integrity and increased risk of prolapse; however, the mechanisms by which elastic fiber damage may contribute to prolapse are poorly understood. Further, the role of elastic fibers in normal vaginal wall mechanics has not been fully ascertained. Therefore, the objective of this study is to investigate the contribution of elastic fibers to murine vaginal wall mechanics. Vaginal tissue from C57BL/6 female mice were mechanically tested using biaxial extension-inflation protocols before and after intraluminal exposure to elastase. Elastase digestion induced marked changes in the vaginal geometry, and biaxial mechanical properties, suggesting that elastic fibers may play an important role in vaginal wall mechanical function. Additionally, a constitutive model that considered two diagonal families of collagen fibers with a slight preference towards the circumferential direction described the data reasonably well before and after digestion. The present findings may be important to determine the underlying structural and mechanical mechanisms of POP, and aid in the development of growth and remodeling models for improved assessment and prediction of changes in structure-function relationships with prolapse development. Keywords: vaginal wall, women's health, mechanical testing, pelvic floor disorders, elastic fibers Disclosures: none.

Evaluation of the bioactivity about anti-sca-1/basic fibroblast growth factor-urinary bladder matrix scaffold for pelvic reconstruction

Introduction and hypothesis: Pelvic support structure injury is the major cause of pelvic organ prolapse. At present, polypropylene-based filler material has been suggested as a common method to treat pelvic organ prolapse. However, it cannot functionally rehabilitate the pelvic support structure. In addition to its poor long-term efficiency, the urinary bladder matrix was the most suitable biological scaffold material for pelvic floor repair. Here, we hypothesize that anti-sca-1 monoclonal antibody and basic fibroblast growth factor were cross-linked to urinary bladder matrix to construct a two-factor bioscaffold for pelvic reconstruction.

METHODS

Through a bispecific cross-linking reagent, sulfosuccinimidyl 4-[N-maleimidomethyl] cyclohexane-1-carboxylate (sulfo-smcc) immobilized anti-sca-1 and basic fibroblast growth factor to urinary bladder matrix. Then scanning electron microscope and plate reader were used to detect whether the anti-sca-1/basic fibroblast growth factor-urinary bladder matrix scaffold was built successfully. After that, the capacity of enriching sca-1 positive cells was measured both in vitro and in vivo. In addition, we evaluated the differentiation capacity and biocompatibility of the scaffold. Finally, western blotting was used to detect the level of fibulin-5 protein.

RESULTS

The scanning electron microscope and plate reader revealed that the double-factor biological scaffold was built successfully. The scaffold could significantly enrich a large number of sca-1 positive cells both in vitro and in vivo, and obviously accelerate cells and differentiate functional tissue with good biocompatibility. Moreover, the western blotting showed that the scaffold could improve the expression of fibulin-5 protein.

CONCLUSION

The anti-sca-1/basic fibroblast growth factor-urinary bladder matrix scaffold revealed good biological properties and might serve as an ideal scaffold for pelvic reconstruction.

Genetics of the extracellular matrix in aortic aneurysmal diseases

Aortic aneurysms are morbid conditions that can lead to rupture or dissection and are categorized as thoracic (TAA) or abdominal aortic aneurysms (AAA) depending on their location. While AAA shares overlapping risk factors with atherosclerotic cardiovascular disease, TAA exhibits strong heritability. Human genetic studies in the past two decades have successfully identified numerous genes involved in both familial and sporadic forms of aortic aneurysm. In this review we will discuss the genetic basis of aortic aneurysm, focusing on the extracellular matrix and how insights from these studies have informed our understanding of human biology and disease pathogenesis.

Biaxial Mechanical Assessment of the Murine Vaginal Wall Using Extension-Inflation Testing

Progress toward understanding the underlying mechanisms of pelvic organ prolapse (POP) is limited, in part, due to a lack of information on the biomechanical properties and microstructural composition of the vaginal wall. Compromised vaginal wall integrity is thought to contribute to pelvic floor disorders; however, normal structure-function relationships within the vaginal wall are not fully understood. In addition to the information produced from uniaxial testing, biaxial extension-inflation tests performed over a range of physiological values could provide additional insights into vaginal wall mechanical behavior (i.e., axial coupling and anisotropy), while preserving in vivo tissue geometry. Thus, we present experimental methods of assessing murine vaginal wall biaxial mechanical properties using extension-inflation protocols. Geometrically intact vaginal samples taken from 16 female C57BL/6 mice underwent pressure-diameter and force-length preconditioning and testing within a pressure-myograph device. A bilinear curve fit was applied to the local stress-stretch data to quantify the transition stress and stretch as well as the toe- and linear-region moduli. The murine vaginal wall demonstrated a nonlinear response resembling that of other soft tissues, and evaluation of bilinear curve fits suggests that the vagina exhibits pseudoelasticity, axial coupling, and anisotropy. The protocols developed herein permit quantification of biaxial tissue properties. These methods can be utilized in future studies in order to assess evolving structure-function relationships with respect to aging, the onset of prolapse, and response to potential clinical interventions.

Differential gene expression of extracellular-matrix-related proteins in the vaginal apical compartment of women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) is a multifactorial disorder that impairs the quality of life (QoL) of older women in particular. The purpose of this study was to elucidate the pathogenesis of POP by focusing on the extracellular matrix (ECM).

METHODS

Patients were classified into two groups-with or without cervical elongation-using the POP quantification system. Specimens were obtained from 29 women with POP during hysterectomy. The expression of fibulin-5, elastin, integrin β1 (ITGβ1), lysyl oxidase-like protein-1 (LOXL1) and collagen in the vagina, uterosacral ligament, and uterine cervix was investigated by quantitative real-time polymerase chain reaction (RT-PCR) and correlation between gene levels and severity of POP examined. The location of proteins was analyzed using immunohistochemical staining and expression of fibulin-5 protein analyzed by Western blotting.

RESULTS

Fibulin-5 and elastin were mainly expressed in lamina propria and fibromuscular layers of the vagina and uterosacral ligament. Gene levels of fibulin-5 and ITGβ1 in uterosacral ligaments increased with severity of POP in women with cervical elongation, while no correlation was observed in women with a normal cervix. In women with uterine cervical elongation, each ECM-related gene significantly increased with POP staging. Furthermore, fibulin-5 protein also increased in the uterosacral ligament and uterine cervix.

CONCLUSIONS

The severity of POP and gene expression of ECM-related proteins were inversely correlated in vaginal tissue in a normal and elongated cervix. These results suggested that the differing progression of the two types of POP have a relationship with ECM-related protein.

Identification of key genes and pathways in pelvic organ prolapse based on gene expression profiling by bioinformatics analysis

PURPOSE

The aim of this study was to elucidate the molecular mechanisms and to identify the key genes and pathways for pelvic organ prolapse (POP) using bioinformatics analysis.

METHODS

The microarray data for GSE53868 included 12 POP and 12 non-POP anterior vaginal wall samples. Differentially expressed genes (DEGs) were identified by GEO2R online tool. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the DAVID database, and a DEG-associated protein-protein interaction (PPI) network was constructed using STRING and visualized in Cytoscape. MCODE was used for module analysis of the PPI network.

RESULTS

A total of 257 upregulated and 333 downregulated genes were identified. GO and KEGG pathway enrichment analyses showed that the upregulated DEGs were strongly associated with immune response, complement activation, classical pathway, phagocytosis, and recognition; the downregulated genes were mainly associated with cellular response to zinc ion, negative regulation of growth, and apoptotic process. Based on the PPI network, IL6, MYC, CCL2, ICAM1, PTGS2, SERPINE1, ATF3, CDKN1A, and CDKN2A were screened as hub genes. The four most significant sub-modules of DEGs were extracted after network module analysis. These genes were mainly associated with the negative regulation of growth and inflammatory response. The KEGG pathway enrichment analysis revealed that these genes were associated with Mineral absorption, Jak-STAT signaling pathway, cytokine-cytokine receptor interaction, and chemokine signaling pathway.

CONCLUSIONS

These microarray data and bioinformatics analyses provide a useful method for the identification of key genes and pathways associated with POP. Moreover, some crucial DEGs, such as IL6, MYC, CCL2, ICAM1, PTGS2, SERPINE1, ATF3, CDKN1A, and CDKN2A, potentially play an important role in the development and progression of POP.

Maintaining Elastogenicity of Mesenchymal Stem Cell-Derived Smooth Muscle Cells in Two-Dimensional Culture

Abdominal aortic aneurysms (AAAs) are localized expansions of the abdominal aorta that grow slowly to rupture. AAA growth is driven by irreversible elastic matrix breakdown in the aorta wall by chronically upregulated matrix metalloproteases (MMPs). Since adult vascular smooth muscle cells (SMCs) poorly regenerate elastic matrix, we previously explored utility of bone marrow mesenchymal stem cells and SMCs derived therefrom (BM-SMCs) for this purpose. One specific differentiated phenotype (cBM-SMCs) generated on a fibronectin substrate in presence of exogenous transforming growth factor-β and platelet-derived growth factor exhibited superior elastogenicity versus other phenotypes, and usefully provided proelastogenic and antiproteolytic stimuli to aneurysmal SMCs. Since in vivo cell therapy demands large cell inoculates, these derived SMCs must be propagated in vitro while maintaining their superior elastogenic, proelastogenic, and antiproteolytic characteristics. In this work, we thus investigated the culture conditions that must be provided to this propagation phase, which ensure that the differentiated SMCs maintain their phenotype and matrix regenerative benefits. Our results indicate that our BM-SMCs retain their phenotype in long-term culture even in the absence of differentiation growth factors and fibronectin substrate, but these conditions must be continued to be provided during postdifferentiation propagation if they are to maintain their superior elastic matrix deposition, crosslinking, and fiber formation properties. Our study, however, showed that cells propagated under these conditions exhibit higher expression of MMP-2, but favorably, no expression of elastolytic MMP-9. Hence, the study outcomes provide crucial guidelines to maintain phenotypic stability of cBM-SMCs during their propagation in two-dimensional culture before their delivery to the AAA wall for therapy.