Decreased endopelvic fascia elastin content in uterine 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.

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.

Induction of Cellular Senescence in Rat Vaginal Fibroblasts and Treatment With Senolytics: An in Vitro Model for the Study of Pelvic Organ Prolapse

OBJECTIVE

The objective of this study was to develop an in vitro model of cellular senescence using rat vaginal fibroblasts and determine the effects of treatment with senolytics.

METHODS

Rat vaginal tissue biopsies were collected. Primary vaginal fibroblasts were isolated and characterized by immunofluorescence. To induce cellular senescence, fibroblasts were treated with etoposide at 3, 10, and 20 mM for 24 hours, followed by treatment with the senolytics dasatinib (1 mM) and/or quercetin (20 mM). After treatment, RNA was extracted and the expression of selected genes was quantified. Immunostaining of senescence markers was also performed.

RESULTS

Fibroblasts were confirmed by positive immunostaining for α-smooth muscle actin and vimentin, and negative immunostaining for pan-cytokeratin. Treatment with etoposide resulted in a dose-dependent increase in expression of the senescence-associated secretory phenotype markers MMP-7, MMP-9, and IL-b1 (P < 0.05) compared with controls. Immunostaining showed increased expression of γ-H2A and p21 after treatment with etoposide. Cells treated with dasatinib and quercetin after etoposide treatment had decreased expression of p21, MMP-7, MMP-9, and IL-1b compared with cells treated only with etoposide (P < 0.05).

CONCLUSIONS

Upregulation of senescence-associated factors provided evidence that senescence can be induced in vaginal fibroblasts in vitro. Furthermore, treatment with the senolytics dasatinib and quercetin abrogated the senescence phenotype induced by etoposide in rat vaginal fibroblasts. Our findings provide a novel model for the study and development of new therapies targeting the disordered extracellular matrix associated with pelvic organ prolapse.

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.

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.

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.

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.

Therapeutic potential of muscle growth promoters in a stress urinary incontinence model

Weakness of urinary sphincter and pelvic floor muscles can cause insufficient urethral closure and lead to stress urinary incontinence. Bimagrumab is a novel myostatin inhibitor that blocks activin type II receptors, inducing skeletal muscle hypertrophy and attenuating muscle weakness. β₂-Adrenergic agonists, such as 5-hydroxybenzothiazolone derivative (5-HOB) and clenbuterol, can enhance muscle growth. We hypothesized that promoting muscle growth would increase leak point pressure (LPP) by facilitating muscle recovery in a dual-injury (DI) stress urinary incontinence model. Rats underwent pudendal nerve crush (PNC) followed by vaginal distension (VD). One week after injury, each rat began subcutaneous (0.3 mL/rat) treatment daily in a blinded fashion with either bimagrumab (DI + Bim), clenbuterol (DI + Clen), 5-HOB (DI + 5-HOB), or PBS (DI + PBS). Sham-injured rats underwent sham PNC + VD and received PBS (sham + PBS). After 2 wk of treatment, rats were anesthetized for LPP and external urethral sphincter electromyography recordings. Hindlimb skeletal muscles and pelvic floor muscles were dissected and stained. At the end of 2 wk of treatment, all three treatment groups had a significant increase in body weight and individual muscle weight compared with both sham-treated and sham-injured rats. LPP in DI + Bim rats was significantly higher than LPP of DI + PBS and DI + Clen rats. There were more consistent urethral striated muscle fibers, elastin fibers in the urethra, and pelvic muscle recovery in DI + Bim rats compared with DI + PBS rats. In conclusion, bimagrumab was the most effective for increasing urethral pressure and continence by promoting injured external urethral sphincter and pelvic floor muscle recovery.

Anatomical structures at risk using different approaches for sacrospinous ligament fixation

For 50 years now, sacrospinous ligament fixation (SSLF) has been used to treat pelvic organ prolapse consequent on altered integrity of the pelvic myofascial structures. It is usually performed vaginally, but it has recently been performed laparoscopically through either an anterior or a posterior approach, with the broad ligament as a landmark to differentiate the two. In the present study, these two laparoscopic approaches were assessed using Thiel-embalmed cadavers. The anterior and posterior approaches were compared in terms of the closest distance to anatomical structures at risk, including pelvic viscera, the obturator nerve, and vascular structures. The posterior approach was more often closer to the investigated vessels and the rectum. The obturator nerve and the ureter were close to both the anterior and posterior approaches. The urinary bladder was closer using the anterior approach. From an anatomical standpoint, therefore, the anterior laparoscopic approach for SSLF is more likely to cause injury to the urinary bladder, whereas the posterior approach is more prone to causing rectal and vessel injuries. This study illustrates, from a basic science perspective, the importance of combining fascia research, novel endoscopic or minimally invasive surgical exposures informed by anatomy, and contemporary trends in gynecology in order to improve patient outcomes. Clin. Anat. 33:522-529, 2020. © 2019 Wiley Periodicals, Inc.

Genome‑wide DNA methylation analysis of uterosacral ligaments in women with pelvic organ prolapse

Pelvic organ prolapse (POP) is an increasingly serious health problem that impairs quality of life and is caused by multiple additive genetic and environmental factors. As the uterosacral ligaments (ULs) provide primary support for the pelvic organs, it was hypothesized that disruption of these ligaments (as a result of aberrant methylation) may lead to a loss of support and eventually contribute to POP. In the present study, whether there are any aberrant methylations in the ULs of patients with POP compared to those of controls was investigated. Genomic DNA was isolated from the ULs of five women with POP and four women without POP, as controls, undergoing hysterectomy for benign conditions. An Illumina Infinium Methylation EPICBeadChips Infinium Human Methylation 850 K bead array was used to investigate the total methylation in the ULs. There were 3,723 differentially methylated CpG sites (Δβ<0.14; P<0.05), including 3,576 hypermethylation and 147 hypomethylation sites in the ULs of patients with POP compared with the normal controls. There were more hypermethylated CpG sites, but a high ratio of hypomethylation between CpG islands and the N-shelf; in the gene structure, there was more hypermethylation than hypomethylation in TSS1500 and the 5′ untranslated region. Gene ontology analysis demonstrated that these differentially methylated genes were associated with ‘cell morphogenesis’, ‘extracellular matrix’, ‘cell junction’, ‘protein binding’ and ‘guanosine triphosphatase activity’. Several significant pathways were identified, including ‘focal adhesion’ and ‘extracellular matrix-receptor interaction pathway’. This study provides evidence that there are differences in genome-wide DNA methylation between ULs in menopausal women with and without POP, and that epigenetic mechanisms may partly contribute to POP pathogenesis.

Vaginal Expression of LOXL1 in Premenopausal and Postmenopausal Women With Pelvic Organ Prolapse

OBJECTIVES

This study aimed to compare cellular expression of lysyl oxidase-like 1 (LOXL1), a key enzyme in elastin metabolism, of premenopausal women with pelvic organ prolapse (POP) compared with premenopausal controls without POP and postmenopausal women with POP. In addition, we examined whether variation of LOXL1 expression was dependent on biopsy site.

METHODS

A standardized protocol was utilized to obtain vaginal biopsies from 30 women (10 premenopausal POP, 10 postmenopausal POP, and 10 premenopausal non-POP). Expression levels of messenger RNA (mRNA) and protein of LOXL1 were determined using real-time quantitative polymerase chain reactions and enzyme-linked immunosorbant assays. Analysis was performed to determine if there were differences between group or biopsy site.

RESULTS

Significant differences in LOXL1 mRNA expression were found between patient groups (P = 0.0033). LOXL1 mRNA expression (relative to 18S) was upregulated in the postmenopausal POP group (54.5 ± 14.7) compared with the premenopausal POP group (5.2 ± 14.7, P = 0.0034) and the premenopausal non-POP group (23 ± 18, P = 0.0359). No significant differences in LOXL1 protein expression (nanogram/milliliter per microgram total protein) were seen between groups (premenopausal POP, 3.2 × 10 ± 6.3 × 10; postmenopausal POP, 4.3 × 10 ± 6.3 × 10; premenopausal non-POP, 5.0 × 10 ± 7.7 × 10; P = 0.15). No differences in mRNA expression were seen between sites (P = 0.74), but significant variation was noted in protein expression (P = 0.001).

CONCLUSIONS

Premenopausal and postmenopausal women with POP exhibit differential expression of LOXL1 suggesting different pathways in the pathogenesis of POP. The role of biopsy location on LOXL1 expression requires further investigation.

Role of transforming growth factor β‑1 in the pathogenesis of pelvic organ prolapse: A potential therapeutic target

The present study aimed to reveal the metabolic alterations of the extracellular matrix (ECM) in uterosacral ligament (USL) with pelvic organ prolapse (POP) and to explore the role of transforming growth factor-β1 (TGF-β1) in pathogenesis of POP. For this purpse, 60 participants who underwent hysterectomy for benign indications were enrolled, 30 of which had symptomatic POP (grade II, III or IV) and composed the POP group, and the other 30 had asymptomatic POP (grade I or less) and served as the controls. Collagen fibers, elastin, matrix metalloproteinase (MMP)-2/9, tissue inhibitor of matrix metalloproteinases (TIMP)-2 and TGF-β1 were examined by Masson's trichrome staining, immunohistochemistry and RT-qPCR using USL biopsies. In vitro, human USL fibroblasts (hUSLFs) were primary cultured, pre-treated with recombinant TGF-β1 (0, 5, or 10 ng/ml) and then subjected to cyclic mechanical stretching (CMS; 0 or 5,333 με strain). Changes in the expression levels of collagen type I/III, elastin, TIMP-2, MMP-2/9 and Smad were detected. Our results revealed that at the tissue level, the expression of collagen fibers, elastin, TIMP-2 and TGF-β1 was significantly reduced in the POP group, while the activities of MMP-2/9 were significantly upregulated, compared with the control group. Statistical analysis indicated that the mRNA expression of TGF-β1 inversely correlated with the severity of POP partially. Our in vitro experimental data demonstrated that a CMS of 5333 με strain promoted the degradation of ECM proteins, inhibited the synthesis of TIMP-2, and upregulated the proteolytic activities of MMP-2/9. Pre-treatment with TGF-β1 attenuated the loss of ECM by stimulating the synthesis of TIMP-2 and inhibiting the activities of MMP-2/9 through the TGF-β1/Smad3 signaling pathway. On the whole, our data indicate that the reduced anabolism and increased catabolism of ECM proteins in USL are the pathological characteristics of POP. TGF-β1 not only has a specific value in predicting the severity of POP, but should also be considered as a novel therapeutic target for POP.

Major review: Exfoliation syndrome; advances in disease genetics, molecular biology, and epidemiology

Exfoliation syndrome (XFS) is a common age-related disorder that leads to deposition of extracellular fibrillar material throughout the body. The most recognized disease manifestation is exfoliation glaucoma (XFG), which is a common cause of blindness worldwide. Recent developments in XFS genetics, cell biology and epidemiology have greatly improved our understanding of the etiology of this complex inherited disease. This review summarizes current knowledge of XFS pathogenesis, identifies gaps in knowledge, and discusses areas for future research.

Methylation of LOXL1 Promoter by DNMT3A in Aged Human Skin Fibroblasts

Lysyl oxidase-like 1 (LOXL1) is an amino-oxidase involved in maturation of elastic fibers. Its downregulation has been associated with elastic fibers repair loss in aging aorta, lung, ligament, and skin. Several evidences of LOXL1 epigenetic silencing by promoter methylation were reported in cancer and cutis laxa syndrome. We hypothesized that this mechanism could be implicated in skin aging process, as far as elastic fibers are also concerned. Anti-DNMT3A chromatin immunoprecipitation was conducted with nuclear extracts from skin fibroblasts isolated from young and elderly individuals, and showed a higher level of DNMT3A protein binding to the LOXL1 promoter in older cells concomitantly to the decrease of LOXL1 mRNA expression and the increase of LOXL1 promoter methylation. Using luciferase reporter assay driven by LOXL1 promoter in HEK293 cells, we demonstrated that LOXL1 transcriptional activity was dramatically reduced when a recombinant DNMT3A was concomitantly overexpressed. LOXL1 promoter transcriptional activity was restored in the presence of a broad-spectrum inhibitor of DNMT activity, 5-aza-2'-deoxycytidine. Finally, to assess whether the interplay between DNMT3A and LOXL1 promoter could be targeted to increase LOXL1 mRNA expression level, an Origanum majorana extract was selected among 43 plant extracts as a new inhibitor of human DNMT3A activity to restore LOXL1 secretion without cytotoxicity in aged skin fibroblasts.

Estradiol plays a role in regulating the expression of lysyl oxidase family genes in mouse urogenital tissues and human Ishikawa cells

The lysyl oxidase (LOX) family encodes the copper-dependent amine oxidases that play a key role in determining the tensile strength and structural integrity of connective tissues by catalyzing the crosslinking of elastin or collagen. Estrogen may upregulate the expression of LOX and lysyl oxidase-like 1 (LOXL1) in the vagina. The objective of this study was to determine the effect of estrogen on the expression of all LOX family genes in the urogenital tissues of accelerated ovarian aging mice and human Ishikawa cells. Mice and Ishikawa cells treated with estradiol (E2) showed increased expression of LOX family genes and transforming growth factor β1 (TGF-β1). Ishikawa cells treated with TGF-β1 also showed increased expression of LOX family genes. The Ishikawa cells were then treated with either E2 plus the TGF-β receptor (TGFBR) inhibitor SB431542 or E2 alone. The expression of LOX family genes induced by E2 was reduced in the Ishikawa cells treated with TGFBR inhibitor. Our results showed that E2 increased the expression of the LOX family genes, and suggest that this induction may be mediated by the TGF-β signal pathway. E2 may play a role in regulating the expression of LOX family genes.

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

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

Changes in muscularis propria of anterior vaginal wall in women with pelvic organ prolapse

The objective of this study was to evaluate the morphological and immunohistochemical alterations of tissue removed from the upper third of anterior vaginal wall in a sample group of the female population presenting homogenous risk factors associated with Pelvic Organ Prolapse (POP). The case study consisted of 14 patients with POP and there were 10 patients in the control group. Patient selection was carried on the basis of specific criteria and all of the patients involved in the study presented one or more of the recognized POP risk factors. Samples were taken from POP patients during vaginal plastic surgery following  colpohysterectomy, and from control patients during closure of the posterior fornix following hysterectomy. Samples were processed for histological and  immunohistochemical analyses for Collagen I and Collagen III, α-Smooth Muscle Actin (α-SMA), Platelet-Derived-Growth-Factor (PDGF), matrix metalloproteinase 3 (MMP3), Caspase3. Immunofluorescence analyses for Collagen I and III and PDGF were also carried out. In prolapsed specimens our results show a disorganization of smooth muscle cells that appeared to have been displaced by an increased collagen III deposition resulting in rearrangement of the muscularis propria architecture. These findings suggest that the increase in the expression of collagen fibers in muscularis could probably due to a phenotypic switch resulting in the dedifferentiation of smooth muscle cells into myofibroblasts. These alterations could be responsible for the compromising of the dynamic functionality of the pelvic floor.

Systemic Associations of Exfoliation Syndrome

Exfoliation syndrome (XFS) is an age-related disease characterized by the production, deposition, and progressive accumulation of a white, fibrillar, extracellular material in many ocular tissues, most prominent on the anterior lens surface and pupillary border. Its prevalence increases steadily with age in all populations. It is the most common identifiable cause of open-angle glaucoma worldwide and is a potentially reversible or even curable disease. First described in Finland in 1917 by Lindberg, it has long been associated with open-angle glaucoma. However, in recent years, it is being increasingly reported in conjunction with a multiplicity of both ocular and systemic disorders, and the number of these is expected to grow, particularly with investigations based on attempts to associate other diseases with those genes known to be associated with XFS. Despite the focus on XFS as a cause of open-angle glaucoma for nearly a century, in reality it is still only an ocular manifestation of a protean systemic disease. It is a unique disorder with extensive and often serious ocular and systemic manifestations and not, as it has long been termed, a "form" or "type" of glaucoma. This misconception has delayed research into the molecular and cellular processes involved in its development, and the underestimation of its overall importance and its underlying causative mechanisms have largely been long ignored. The purpose of this article is to review the systemic disorders which are becoming increasingly associated with XFS. Reviews of epidemiology, genetics, biomarkers, molecular mechanisms of development, and ocular findings may be found elsewhere.

Expression of fibulin-5 in the skin of patients with rectal prolapse

AIM

Components of connective tissue other than collagen have been found to be involved in patients with rectal prolapse. The organization of elastic fibres differs between controls and subsets of patients with rectal prolapse, and their importance for maintaining the structural and functional integrity of the pelvic floor has been demonstrated in transgenic mice, with animals which have a null mutation in fibulin-5 (Fbln5(i/i)) developing prolapse. This study aimed to compare fibulin-5 expression in the skin of patients with and without rectal prolapse.

METHOD

Between January 2013 and February 2014, skin specimens were obtained during surgery from 20 patients with rectal prolapse and from 21 without prolapse undergoing surgery for other indications. Fibroblasts from the skin were cultured and the level of fibulin-5 expression was determined on cultured fibroblasts, isolated from these specimens by quantitative real-time polymerase chain reaction. Immunohistochemistry was performed on fixed tissue specimens to assess fibulin-5 expression.

RESULTS

Fibulin-5 mRNA expression and fibulin-5 staining intensity were significantly lower in young male patients with rectal prolapse compared with age-matched controls [fibulin-5 mean ± SD mRNA relative units, 1.1 ± 0.41 vs 0.53 ± 0.22, P = 0.001; intensity score, median (range), 2 (0-3) vs 1 (0-3), P = 0.05]. There were no significant differences in the expression of fibulin-5 in women with rectal prolapse compared with controls.

CONCLUSION

Fibulin-5 may be implicated in the aetiology of rectal prolapse in a subgroup of young male patients.

Structural study of endopelvic fascia in prostates of different weights. Anatomic study applied to radical prostatectomy

PURPOSE

To evaluate the structure of the endopelvic fascia in prostates of different weights.

METHODS

We studied 10 patients with BPH (prostates> 90 g); 10 patients with prostate adenocarcinoma (PAC) (prostates< 60 g) and five young male cadavers (control group). During the surgery a small sample of endopelvic fascia was obtained. We analyzed elastic fibers, collagen and smooth muscle. The stereological analysis was done with the Image Pro and Image J programs. Means were statistically compared using the one-way ANOVA with the Bonferroni test and a p<0.05 was considered statistically significant.

RESULTS

The mean of the prostate weight was 122 g in BPH patients, 53.1g in PAC patients and 18.6g in control group. Quantitative analysis documented that there are no differences (p=0.19) in Vv of elastic fibers and in Vv of type III collagen (p=0.88) between the three groups. There was a significant difference (p=0<0.0001) in the quantification of SMC in patients with prostates > 90 g (mean=9.61%) when compared to patients with prostates < 60 g (mean=17.92%) and with the control group (mean=33.35%).

CONCLUSION

There are differences in endopelvic fascia structure in prostates> 90 g, which can be an additional factor for pre-operatory evaluation of radical prostatectomy.

Mutation screen of LOXL1 in patients with female pelvic organ prolapse

OBJECTIVES

The LOXL1 (lysyl oxidase-like 1) gene encodes a copper-dependent monoamine oxidase that catalyzes the deamination of a lysine residue in the cross-linking of tropoelastin monomers to form elastin. LOXL1-KO mice do not deposit normal elastic fibers in their genitourinary tract resulting in postpartum pelvic organ prolapse and lower urinary tract dysfunction with decreased bladder capacity and lower voiding pressure. We sought to identify which single nucleotide polymorphisms in the LOXL1 coding sequence play a role in female pelvic organ prolapse.

METHODS

A total of 66 patients were screened, 48 in the case group and 18 in the control group. The 7 exons of LOXL1 were evaluated for any polymorphisms.

RESULTS

Three missense sequence changes (Arg141Leu, Gly153Asp, and Ser159Ala) and 3 silent mutations (Asp292Asp, Ala320Ala, and Ile521Ile) were identified. None of these polymorphisms were found to differ significantly in frequency in the case group compared with the control group.

CONCLUSIONS

Our findings do not support an association of any LOXL1 exonal single nucleotide polymorphisms with the diagnosis of female pelvic organ prolapse.

Ocular and systemic manifestations of exfoliation syndrome

Exfoliation syndrome is an age-related disease characterized by the production and progressive accumulation of a fibrillar extracellular material in many ocular tissues. It leads to the most common identifiable cause of open-angle glaucoma worldwide, comprising the majority of glaucoma in some countries. The material in the eye appears as white deposits on the anterior lens surface and/or pupillary border. During pupillary movement, the iris scrapes exfoliation material from the lens surface, while the material on the lens causes rupture of iris pigment epithelial cells, with concomitant pigment dispersion into the anterior chamber and its deposition on anterior chamber structures. Exfoliation material can be found in many different organs. It is an ischemic disease and is associated with elevated serum homocysteine. Systemic associations include transient ischemic attacks, hypertension, angina, myocardial infarction, cerebrovascular and cardiovascular disease, aortic aneurysm, Alzheimer disease, and hearing loss. The discovery in 2007 of nonsynonymous single nucleotide polymorphisms in the LOXL1 (lysyl oxidase-like 1) gene are expected to make a major impact not only in understanding exfoliation syndrome, but in leading to new avenues of therapy.

Association between pelvic organ prolapse and stress urinary incontinence with collagen

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

Animal models of female pelvic organ prolapse: lessons learned

Pelvic organ prolapse is a vaginal protrusion of female pelvic organs. It has high prevalence worldwide and represents a great burden to the economy. The pathophysiology of pelvic organ prolapse is multifactorial and includes genetic predisposition, aberrant connective tissue, obesity, advancing age, vaginal delivery and other risk factors. Owing to the long course prior to patients becoming symptomatic and ethical questions surrounding human studies, animal models are necessary and useful. These models can mimic different human characteristics - histological, anatomical or hormonal, but none present all of the characteristics at the same time. Major animal models include knockout mice, rats, sheep, rabbits and nonhuman primates. In this article we discuss different animal models and their utility for investigating the natural progression of pelvic organ prolapse pathophysiology and novel treatment approaches.

Human copper-dependent amine oxidases

Copper amine oxidases (CAOs) are a class of enzymes that contain Cu(2+) and a tyrosine-derived quinone cofactor, catalyze the conversion of a primary amine functional group to an aldehyde, and generate hydrogen peroxide and ammonia as byproducts. These enzymes can be classified into two non-homologous families: 2,4,5-trihydroxyphenylalanine quinone (TPQ)-dependent CAOs and the lysine tyrosylquinone (LTQ)-dependent lysyl oxidase (LOX) family of proteins. In this review, we will focus on recent developments in the field of research concerning human CAOs and the LOX family of proteins. The aberrant expression of these enzymes is linked to inflammation, fibrosis, tumor metastasis/invasion and other diseases. Consequently, there is a critical need to understand the functions of these proteins at the molecular level, so that strategies targeting these enzymes can be developed to combat human diseases.

The role of mode of delivery on elastic fiber architecture and vaginal vault elasticity: a rodent model study

We report on an experimental study of the role of mode of delivery and pregnancy on the architecture of vaginal elastic fibers and vaginal vault elasticity in female Sprague-Dawley rats. In primiparous rats submitted to spontaneous or Cesarean delivery and virgin rats submitted to simulated delivery, the tortuosity of elastic fibers (defined as the ratio of length to end-to-end distance) was observed to decrease when measured from two days to two weeks postpartum. In addition, the measured tortuosity of elastic fibers in multiparous rats was greater than that of virgin rats. The tortuosity of elastic fibers of all rats measured at two days postpartum was found to be similar to that of multiparous rats. At two weeks postpartum the measured tortuosity of vaginal elastic fibers was indistinguishable from virgin rats, regardless of the delivery method. Borrowing from the field of polymer physics, a model is suggested that connects elastic fiber tortuosity to the resulting tension under an applied stress; fibers having high tortuosity are expected to provide less structural support than more linear, low tortuosity fibers. To probe the macroscopic effects in elasticity due to architectural changes observed in elastic fibers, we have measured the stiffness of the vaginal vault in each cohort using a pressure-infusion system. The vaginal vault stiffness of all primiparous rats measured two weeks postpartum was greater than that measured two days postpartum. In addition, the vaginal vault of virgin rats was stiffer than that of multiparous rats. These observations confirmed that vaginal vault elastic fibers undergo significant remodeling due to pregnancy and parturition, and that the complex remodeling may be a significant contributor to tissue elasticity. Remarkably, regardless of the mode of delivery or simulated tissue trauma, elastic fiber tortuosity is observed to decrease from two days to two weeks postpartum indicating the onset of repair and recovery of tissue stiffness.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Induced Regenerative Elastic Matrix Repair in LOXL1 Knockout Mouse Cell Cultures: Towards Potential therapy for Pelvic Organ Prolapse

Impaired elastic matrix remodeling occurs in reproductive tissues after vaginal delivery. This has been linked to development of pelvic organ prolapse (POP) for which there currently is no pharmacologic therapy. Hyaluronan oligomers and transforming growth factor beta 1 (termed elastogenic factors, EFs) have been shown to significantly enhance tropoelastin synthesis, elastic fiber assembly, and crosslinking by adult vascular smooth muscle cells (SMCs). The goal of this study was to ascertain if these factors similarly improve the quantity and quality of elastic matrix deposition by vaginal SMCs (VSMCs) isolated from lysyl oxidase like-1 knock out (LOXL1 KO) mouse model of POP. Cells isolated from whole vagina of a LOXL1 KO mouse (multiparous, stage 3 prolapse) were cultured and identified as SMCs by their expression of various SMC markers. Passage 2 vaginal SMCs (VSMCs; 3×10⁴/10 cm²) were cultured for 21 days with EFs. Cell layers and spent medium aliquots were assessed for elastin content and quality. EF-treated VSMCs proliferated at a similar rate to untreated controls but synthesized more total elastin primarily in the form of soluble matrix elastin. Elastin mRNA was also increased compared to controls. The elastic matrix was significantly denser in EF-treated cultures, which was composed of more mature, non-interrupted elastic fibers that were absent in controls. The results are promising towards development of a therapy to enhance regenerative elastic matrix repair in post-partum female pelvic floor tissues.

Histologic and immunohistochemical studies of rectus sheath in obese patients

BACKGROUND

Obesity is a well-established risk factor for incisional hernia development. The exact causative factors have not been clearly defined, and development may result from structural disruptions in the connective tissue of the fasciae. The goal of this study was to compare the content of elastin in the rectus muscle sheath of obese patients and nonobese controls.

MATERIALS AND METHODS

The study group consisted of 20 patients with body mass index over 35 kg/m(2) and the control group included 19 patients with normal-range body mass index. The biopsy specimens harvested during surgery were subjected to histologic evaluation, an immunohistochemical reaction with monoclonal anti-elastin antibodies, and the DAB chromatic reaction. The photomicrographs were evaluated using ImageJ software and the percentage of the area affected by the color reaction was assessed. A statistical evaluation was performed.

RESULTS

The specimens harvested from persons in the control group showed in hematoxylin-eosin staining a high density of fibrous elements, arranged in regular bundles. In specimens obtained from the morbidly obese, the density of the fibers was lower and their architecture was disrupted; the bundles were thinner and less regularly arranged. Most photographs show adipose tissue infiltrating the structure of the fascia. Statistical analysis of the percentage of the area occupied by elastin showed a statistically significant difference in favor of the controls.

CONCLUSIONS

The quantitative and qualitative changes in the elastin content of rectus abdominis muscle sheath fascia in the obese population may indicate a possible local mechanism influencing the development of incisional hernias.

Elastic fiber assembly in the adult mouse pubic symphysis during pregnancy and postpartum

Impairment of pelvic organ support has been described in mice with genetic modifications of the proteins involved in elastogenesis, such as lysyl oxidase-like 1 (LOXL1) and fibulin 5. During pregnancy, elastic fiber-enriched pelvic tissues are modified to allow safe delivery. In addition, the mouse pubic symphysis is remodeled in a hormone-controlled process that entails the modification of the fibrocartilage into an interpubic ligament (IpL) and the relaxation of this ligament. After first parturition, recovery occurs to ensure pelvic tissue homeostasis. Because ligaments are the main supports of the pelvic organs, this study aimed to evaluate elastogenesis in the IpL during mouse pregnancy and postpartum. Accordingly, virgin, pregnant, and postpartum C57BL/6 mice were studied using light, confocal, and transmission electron microscopy as well as Western blots and real-time PCR. Female mice exhibited the separation of the pubic bones and the formation, relaxation, and postpartum recovery of the IpL. By the time the IpL was formed, the elastic fibers had increased in profile length and diameter, and they consisted of small conglomerates of amorphous material distributed among the bundles of microfibrils. Our analyses also indicated that elastin/tropoelastin, fibrillin 1, LOXL1/Loxl1, and fibulin 5 were spatially and temporally regulated, suggesting that these molecules may contribute to the synthesis of new elastic fibers during IpL development. Overall, this work revealed that adult elastogenesis may be important to assure the elasticity of the pelvic girdle during preparation for parturition and postpartum recovery. This finding may contribute to our understanding of pathological processes involving elastogenesis in the reproductive tract.

Decreased expression of elastin, fibulin-5 and lysyl oxidase-like 1 in the uterosacral ligaments of postmenopausal women with pelvic organ prolapse

AIM

Pelvic organ prolapse is associated with defects in connective tissues, including elastic fibers. The purpose of this study was to investigate the expression of fibulin-5 and lysyl oxidase-like 1 (LOXL1), which play an essential role in the synthesis and assembly of elastic fibers, in the uterosacral ligaments of women with advanced pelvic organ prolapse (POP) compared with controls.

METHOD

Specimens were obtained prospectively during transvaginal or abdominal hysterectomy from 30 women with advanced pelvic organ prolapse and 30 controls matched to the POP group for age and parity among postmenopausal women with benign gynecologic diseases. The expressions of elastin, fibulin-5 and LOXL1 in uterosacral ligaments were measured by immunohistochemistry.

RESULTS

We detected a decreased, sometimes absent, expression of fibulin-5 and LOXL1 in the uterosacral ligaments of women with POP, despite a positive expression of elastin. There was a decrease in positive percentage of LOXL1 in the POP group (23.3%) compared with the controls (60%) (P = 0.004). With immunolabeling intensity classified as negative, weak, moderate or strong, there was a decrease in the expression of fibulin-5 in the POP group (P = 0.049). We also detected a significantly decreased expression of LOXL1 in the POP group (P = 0.001).

CONCLUSIONS

There was decreased expression of fibulin-5 and LOXL1 in the uterosacral ligaments of patients with pelvic organ prolapse, while the elastin expression was equivalent, which may suggest the possibility of defects in elastic fiber remodeling in the postpartum period and contribute to POP.

Knockdown of Hoxa11 in vivo in the uterosacral ligament and uterus of mice results in altered collagen and matrix metalloproteinase activity

Homeobox (HOX) genes are evolutionarily conserved genes encoding transcription factors that regulate mammalian embryonic growth and development of the urogenital tract. In both humans and mice, HOXA11 persists in the adult reproductive tract and is thought to play an important role in maintaining tissue developmental plasticity by regulating the expression of genes involved in extracellular matrix metabolism in the reproductive organs. Previously, we have shown that HOXA11 is necessary for development of the uterosacral ligaments in mice and is deficient in women with pelvic organ prolapse. Therefore, we hypothesized that Hoxa11 regulates the synthesis and/or metabolism of collagens in the uterosacral ligaments and uterus, and tested this by establishing an in utero and peritoneal Hoxa11 gene knockdown system in C57/BL6 mice using vectors bearing Hoxa11 short hairpin RNA. Specific knockdown of Hoxa11 transcripts and protein levels were confirmed versus control vectors. Protein and mRNA expression of collagen types I and III exhibited significant decreases following Hoxa11 knockdown according to Western blot analysis and real-time PCR. Tissue inhibitor of matrix metalloproteinase 1 (MMP1) expression also exhibited a significant decrease. Gelatinase zymography confirmed increases in pro-MMP2 and MMP9, as well as activated MMP2, following Hoxa11 knockdown. These results reveal that Hoxa11 knockdown in the uterosacral ligaments and uterus increases extracellular matrix degradation. More importantly, it suggests a mechanism in the weakening of the pelvic floor support in women, because decreased HOXA11 gene expression has been reported to be associated with decreased collagen and increased MMP2 expression in the uterosacral ligaments of women with pelvic organ prolapse.

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

INTRODUCTION AND HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Alterations in connective tissue metabolism in stress incontinence and prolapse

PURPOSE

We describe current knowledge about collagen/elastin and extracellular matrix metabolism in the genitourinary tract with special emphasis on stress urinary incontinence. We also explored the influence of genetics and reproductive hormones on extracellular matrix metabolism.

MATERIALS AND METHODS

We performed a MEDLINE® search from 1995 to February 2011 using the key words stress urinary incontinence, pelvic organ prolapse, extracellular matrix, collagen, elastin, matrix metalloproteinase, collagenase, tissue inhibitors of matrix metalloproteinase, elastin metabolism, elastase, connective tissue, supportive tissue, mechanical stress, biomechanical properties, selective estrogen receptor modulators, transforming growth factor-β and wound healing.

RESULTS

The literature searched produced data on 4 areas of significance for extracellular matrix metabolism in patients with stress urinary incontinence and prolapse, including collagen, elastin and transforming growth factor-β. Data on collagen metabolism continue to support the hypothesis of increased turnover involving matrix metalloproteinases and serine proteases in pelvic tissues of affected individuals. Elastin metabolism studies suggest increased degradation but also abnormal elastin fiber synthesis. Epidemiological data indicate a genetic predisposition to abnormal extracellular matrix in affected individuals while human tissue and animal models reveal differential expression of candidate genes involved in structural proteins. Transforming growth factor-β pathways have been documented to be involved in stress urinary incontinence in human tissues and animal models. Finally, these extracellular matrix metabolisms are modulated by reproductive hormones and selective estrogen receptor modulators.

CONCLUSIONS

Pelvic tissue from women with stress urinary incontinence and pelvic organ prolapse show a genetic predisposition to abnormal extracellular matrix remodeling, which is modulated by reproductive hormones, trauma, mechanical stress load and aging. This progressive remodeling contributes to stress urinary incontinence/pelvic organ prolapse by altering normal tissue architecture and mechanical properties.

The calpain system as a potential target for pelvic muscle reinforcement

The fascial and muscular components within the pelvic floor create a support mechanism that facilitates storage and voiding of urine. Their constituents are mainly fibrillar collagens I and III, which are responsible for maintaining tensile strength. Stretching and recoiling is enabled by the elastic fibers consisting of elastin on a scaffold of microfibrils, fibrillin-1 and -2. Calpains are intracellular Ca2+ -dependent cysteine proteases found in almost all eukaryotes and some bacteria. Calpains display limited proteolytic activity at neutral pH, proteolyzing substrates to transform and modulate their structures and activities, and are therefore called “modulator proteases”. By making selective limited proteolytic cleavages, they modulate the activity of enzymes, including key signaling molecules, and induce specific cytoskeletal rearrangements, accounting for their roles in signal transduction and structural stabilization. Understanding these mechanisms should provide avenues for novel therapeutic strategies to treat pathological processes such as urinary incontinence and pelvic prolapse.

Pelvic floor disorders: linking genetic risk factors to biochemical changes

Pelvic floor disorders (PFDs) such as stress urinary incontinence (SUI) and pelvic organ prolapse (POP) may share a common pathophysiological process related to pelvic floor tissue laxity and loss of support. We reviewed recent literature on observed biochemical changes in women with SUI and POP, linking them to genetic predisposition. We found that studies of pelvic tissues showed differences between control subjects and women with POP and SUI in collagen and elastin structure at a molecular and fibrillar level. Studies were heterogeneous but showed a trend towards decreased collagen and elastin content. The contribution of matrix metalloproteinases to increased collagenolysis can be related to genetic polymorphisms present in higher frequency in women with PFD. Extracellular matrix (ECM) protein turnover plays a role in the development of POP and SUI, but much remains to be understood of this complex dynamic interplay of enzymes, proteins and molecules. Genotyping of candidate genes participating in ECM formation will elucidate the missing link between the manifestation of the disease and the biochemical changes observed systematically, in addition to those in the pelvic floor.

Genetics of pelvic organ prolapse: crossing the bridge between bench and bedside in urogynecologic research

An increasing number of scientists have studied the molecular and biochemical basis of pelvic organ prolapse (POP). The extracellular matrix content of the pelvic floor is the major focus of those investigations and pointed for potential molecular markers of the dysfunction. The identification of women predisposed to develop POP would help in the patients' management and care. This article includes a critical analysis of the literature up to now; discusses implications for future research and the role of the genetics in POP.

Changes of glycoprotein and collagen immunolocalization in the uterine artery wall of postmenopausal women with and without pelvic organ prolapse

Pelvic organ prolapse (POP) is accompanied by an altered composition of the extracellular matrix (ECM). However, it is unclear whether the changed ECM is the cause or the consequence of POP, as stretching of the tissue may have an effect on the composition of the ECM. To address this question, we analyzed the connective tissues of the uterine artery wall of postmenopausal women with and without POP. The uterine artery wall is stretched in patients with POP, but this stretching is unlikely to cause the POP. Twenty-one women (13 with POP and 8 without POP) hospitalized for hysterectomy were included in this study. Tissue samples from the uterine artery were analyzed for collagen (types I, III, IV, V and VI) and other ECM proteins (fibronectin, laminin, tenascin, vitronectin and elastin) using immunofluorescence microscopy. Results revealed that uterine artery samples of women with prolapse showed a significantly weaker immunoreactivity to type VI collagen, vitronectin and elastin and a stronger immunostaining for type III collagen and tenascin as compared to control samples. Our results suggest that the ECM may be altered in response to mechanical stretch. Changes in the ECM composition as observed in POP may not necessarily be the reason for the development of pelvic floor relaxation in postmenopausal women.

Joint hypermobility and rectal evacuatory dysfunction: an etiological link in abnormal connective tissue?

BACKGROUND

  Previous studies report an association between joint hypermobility (JHM), as a clinical feature of underlying connective tissue (CT) disorder, and pelvic organ prolapse. However, its association with rectal evacuatory dysfunction (RED) has not been evaluated. To investigate the prevalence of JHM in the general population and in patients with symptoms of RED referred for anorectal physiological investigation.

METHODS

Bowel symptom and Rome III questionnaires to detect irritable bowel syndrome were sent to 273 patients with RED. Patients then underwent full investigation, including evacuation proctography. A validated 5-point self-reported questionnaire was used to assess JHM in both the patient group and 100 age- and sex-matched controls [87 female, median age 55 (range 28-87)].

KEY RESULTS

Seventy-three patients were excluded from analysis (incomplete questionnaire or investigation). Of 200, 65 patients [32%: 63 female, median age 52 (range 15-80)] and 14% of controls (P = 0.0005 vs patients) had features satisfying criteria for JHM. Overall constipation score (P < 0.0001), abdominal pain (P = 0.003), need for manual assistance (P = 0.009), and use of laxatives (P = 0.03) were greater in the JHM group than the non-JHM group. On proctography, 56 of JHM patients (86%) were found to have significant morphological abnormalities (e.g. functional rectocoele), compared with 64% of the non-JHM group (P = 0.001).

CONCLUSIONS & INFERENCES

The greater prevalence of JHM in patients with symptoms of RED, and the demonstration of significantly higher frequencies of morphological abnormalities than those without JHM, raises the possibility of an important pathoaetiology residing in either an enteric or supporting pelvic floor abnormality of CT.

[Connective tissue and prolapse genesis]

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