Changes of collagen type III and decorin in paraurethral connective tissue from women with stress urinary incontinence and prolapse

Advances in the molecular pathogenesis and cell therapy of stress urinary incontinence

Stress urinary incontinence (SUI) is very common in women. It affects patients' mental and physical health, and imposed huge socioeconomic pressure. The therapeutic effect of conservative treatment is limited, and depends heavily on patient persistence and compliance. Surgical treatment often brings procedure-related adverse complications and higher costs for patients. Therefore, it is necessary to better understand the potential molecular mechanisms underlying stress urinary incontinence and develop new treatment methods. Although some progress has been made in the basic research in recent years, the specific molecular pathogenic mechanisms of SUI are still unclear. Here, we reviewed the published studies on the molecular mechanisms associated with nerves, urethral muscles, periurethral connective tissue and hormones in the pathogenesis of SUI. In addition, we provide an update on the recent progresses in research on the use of cell therapy for treating SUI, including research on stem cells therapy, exosome differentiation and gene regulation.

Molecular Processes in Stress Urinary Incontinence: A Systematic Review of Human and Animal Studies

Stress urinary incontinence (SUI) is a common and burdensome condition. Because of the large knowledge gap around the molecular processes involved in its pathophysiology, the aim of this review was to provide a systematic overview of genetic variants, gene and protein expression changes related to SUI in human and animal studies. On 5 January 2021, a systematic search was performed in Pubmed, Embase, Web of Science, and the Cochrane library. The screening process and quality assessment were performed in duplicate, using predefined inclusion criteria and different quality assessment tools for human and animal studies respectively. The extracted data were grouped in themes per outcome measure, according to their functions in cellular processes, and synthesized in a narrative review. Finally, 107 studies were included, of which 35 used animal models (rats and mice). Resulting from the most examined processes, the evidence suggests that SUI is associated with altered extracellular matrix metabolism, estrogen receptors, oxidative stress, apoptosis, inflammation, neurodegenerative processes, and muscle cell differentiation and contractility. Due to heterogeneity in the studies (e.g., in examined tissues), the precise contribution of the associated genes and proteins in relation to SUI pathophysiology remained unclear. Future research should focus on possible contributors to these alterations.

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.

BMMSC-sEV-derived miR-328a-3p promotes ECM remodeling of damaged urethral sphincters via the Sirt7/TGFβ signaling pathway

Background

Stress urinary incontinence (SUI) is a common and bothersome condition. Invasive surgery will always be considered after conservative treatment fails, but the rates of postoperative complications and long-term recurrence are high. Thus, a new treatment strategy is still needed. In recent years, bone marrow mesenchymal stem cells (BMMSC) have shown great promise for SUI treatment. The therapeutic effects of BMMSC on SUI are achieved mainly by paracrine pathway signaling molecules, such as small extracellular vesicles (sEV). sEV are recognized as essential mediators of cell-to-cell communication. However, the therapeutic effects and detailed mechanisms of BMMSC-derived sEV in SUI remain mostly unexplored.

Methods

The effects of BMMSC-sEV on extracellular matrix (ECM) metabolism were assessed in vitro and in vivo. In a SUI rat model, TGF-β1 signaling was examined with or without BMMSC-sEV stimulation. sEV miRNAs were deeply sequenced, and the most likely miRNAs were evaluated as mediators of the TGF-β1 signaling pathway.

Results

BMMSC-sEV enhanced the synthesis of ECM components, including elastin, collagen I, and collagen III, and improved urethral function. Furthermore, BMMSC-sEV activated TGF-β1 signaling in primary fibroblast cells and in rat urethras. Several differentially expressed miRNAs were identified in the BMMSC-sEV. Bioinformatics analysis and in vitro studies showed that BMMSC-sEV miR-328a-3p can be transferred from BMMSC to fibroblasts and can regulate the Sirt7/TGF-β1 signaling pathway.

Conclusion

BMMSC-sEV promote ECM remodeling of damaged urethral sphincters by transferring miR-328a-3p to regulate the Sirt7/TGF-β1 signaling pathway.

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.

Role of vasoactive intestinal peptide and pituitary adenylate cyclase activating polypeptide in the vaginal wall of women with stress urinary incontinence and pelvic organ prolapse

Pelvic floor connective tissue degeneration is closely associated with retrogradation of its dominating nerve fibers. We hypothesized that some neuropeptides from pelvic floor tissue might be involved in the pathological progress of stress urinary incontinence (SUI) and pelvic organ prolapse (POP) in women. Thirty premenopausal and 31 postmenopausal patients participated in the study. The morphological appearance in the vaginal tissue was examined. The vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide-38 (PACAP) immunoreactivities (ir-VIP, ir-PACAP) were tested by immunohistochemistry and radioimmunoassay. We found that the VIP and PACAP immunostainings were weaker and sparser, and ir-VIP and ir-PACAP levels were significantly decreased in the anterior vaginal wall in the premenopausal and postmenopausal SUI or POP patients. Ir-VIP and ir-PACAP levels were reversely correlated with the age and menopausal status in the SUI or POP patients. Our data suggest that VIP and PACAP may participate in the pathophysiological process of SUI and POP.