The aim of the present study was to investigate the protective effect of integrin β1 in the treatment of stress urinary incontinence (SUI) by electrical stimulation, and the underlying mechanisms by which electrical stimulation regulates the collagen metabolism of female vaginal wall fibroblasts (FVWFs). FVWFs obtained from the vaginal wall tissue of patients with (Ingelman‑Sundberg scale; grade II, n=8; grade III, n=10) or without (n=8) SUI during gynecological operations were isolated by enzymatic digestion and subsequently identified by immunocytochemistry. Following this, cultured FVWFs were treated with an inhibitor of integrin β1, recombinant human integrin β1 and electrical stimulation (100 mv/mm, 2 h, 20 Hz), followed by total mRNA and protein extraction. mRNA and protein expression levels of integrin β1, transforming growth factor (TGF)‑β1 and collagen (COL) I and III in FVWFs were quantified by reverse transcription‑quantitative PCR (RT‑qPCR) and western blot analysis respectively. Integrin β1, TGF‑β1 and COL I and III expression levels were decreased in patients with SUI compared with healthy controls, and the grade III group had lower levels than the grade II group. Following electrical stimulation treatment, the expression levels of TGF‑β1, COL I and III were enhanced in the grade II group, but not in the grade III group. Nevertheless, the inhibitor of integrin β1 reduced the protective effect of electrical stimulation in the grade II group. In addition, electrical stimulation combined with recombinant human integrin β1 could also protect cells from SUI in the grade III group. The present study provides evidence for the increased degradation of the extracellular matrix and integrin β1 in the vaginal wall tissues of patients with SUI, and the protective effect of electrical stimulation against SUI via integrin β1. These results provide a novel mechanism for the treatment of SUI using electrical stimulation.

Apoptosis and oxidative damage are involved in the pathogenesis and progression of stress urinary incontinence (SUI). Our previous results indicate that cell apoptosis and oxidative damage increase in a mouse model of mechanical injury-induced SUI and in fibroblasts treated with excessive mechanical strain. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a well-characterized global antioxidant gene inducer that can reduce oxidative damage and apoptosis. Therefore, we predicted that Nrf2 may have a protective role in mechanical trauma-induced SUI. To test this hypothesis, a mouse model of vaginal distension- (VD-) induced SUI was established. Leak point pressure (LPP); levels of apoptosis, apoptosis-related proteins, and peroxidation products; and the activities of antioxidative proteins in the anterior vaginal wall were measured in wild-type (Nfe2l2+/+) C57BL/6 mice and Nrf2-knockout mice (Nfe2l2-/-). The results showed that Nrf2 knockout aggravated VD-induced reduction in LPP, increase in cell apoptosis and peroxidation product levels, decrease in antioxidative protein activities, and alterations in apoptosis-related protein levels in the vaginal walls of mice. To further confirm the role of Nrf2 in mechanical trauma-induced apoptosis and SUI, VD was performed on mice overexpressing Nrf2 via in vivo transfection of LV-Nfe2l2. The results showed that Nrf2 overexpression significantly alleviated VD-induced abnormalities in the anterior vaginal wall. Taken together, our data suggested that Nrf2 is a potential protective factor in mechanical trauma-induced apoptosis in a mouse model of SUI. Antioxidative therapy may be a promising treatment for mechanical trauma-related SUI.

We investigated the effect of punicalagin (PUN; 2,3-hexahydroxydiphenoyl-gallagyl-D-glucose), on mechanical-trauma-induced stress urinary incontinence (SUI) in mouse and the mechanisms underlying any effects.

Stress urinary incontinence (SUI) is a public health issue attributed to weakened pelvic supporting tissues. Electrical stimulation (ES) is one of the first-line conservative treatments for SUI. However, the underlying mechanism of ES in the treatment of SUI is not clear. Here, we show that ES suppresses cell apoptosis and upregulates collagen expression by functioning as a cell growth inducer to activate the calpain 2/talin 1/integrin β1/transforming growth factor (TGF)-β1 axis. Specifically, ES promoted Ca2+ to flow into the cytoplasm through the calcium channel, Cav 3.2, thereby activating calpain 2. Then, the activated calpain 2 cleaved talin 1, which induced the activation of integrin β1 and upregulated the TGF-β1-mediated transcription of collagen I and III. Notably, blocking Cav 3.2 suppressed calcium influx and inhibited the activation of downstream proteins. Furthermore, the knockdown of calpain 2 resulted in the reduction of cleaved talin 1, and the shRNA-integrin β1 treatment downregulated the level of activated integrin β1 and the expression of TGF-β1-induced collagen I and III. An association of the ES-modulated collagen I and III upregulation with the therapeutic effect of the ES-Ca2+/calpain 2/talin 1/integrin β1/TGF-β1 axis was demonstrated in mouse fibroblast and mouse SUI models established through vaginal distension (VD). This outcome provides insight into clinical diagnosis and treatment.

Stress urinary incontinence (SUI) is a common hygienic problem affecting the quality of women's life worldwide. In this research, we revealed the involvement and regulation of extracellular matrix (ECM) remodeling, oxidative damage, and TGF-β1 signaling in the pathological mechanisms of mechanical trauma-induced SUI. We found that excessive mechanical strain significantly increased apoptosis rate, decreased cell viability and ECM production, and broke the balance of MMPs/TIMPs compared with the nonstrain control (NC) group. The expression levels of TGFβ1, p-Smad3, Nrf2, GPx1, and CAT were downregulated, the production of ROS, 8-OHdG, 4-HNE, and MDA was increased, and the nuclear translocation of Smad2/3 was suppressed after 5333 μstrain's treatment. Both mTGF-β1 pretreatment and Nrf2 overexpression could reverse mechanical injury-induced TGFβ1/Smad3 signaling inhibition and ECM remodeling, whereas mTGF-β1 had no effect on Nrf2 expression. Nrf2 overexpression significantly alleviated mechanical injury-induced ROS accumulation and oxidative damage; in contrast, Nrf2 silencing exhibited opposite effects. Besides, vaginal distention- (VD-) induced in vivo SUI model was used to confirm the in vitro results; Nrf2 knockout aggravates mechanical trauma-induced LPP reduction, ECM remodeling, oxidative damage, and TGF-β1/Smad3 suppression in mice. Therefore, we deduce that mechanical injury-induced ECM remodeling might be associated with Nrf2/ARE signaling suppression mediating TGF-β1/Smad3 signaling inhibition. This might reflect a new molecular target for SUI researches.

Electrical stimulation (ES) therapy has good effects in patients with nervous system injury-related diseases. ES promotes nerve cell regeneration and stimulates Schwann cells to express neurotrophic factors. The incidence of stress urinary incontinence (SUI) among elderly people is increasing. Some studies suggest that damage to the pudendal nerve is closely related to the pathogenesis of SUI. It has also been found that pelvic ES can reduce SUI symptoms in a rat model of SUI caused by pudendal nerve injury. Clinically, pelvic floor electrical stimulation is effective in patients with mild to moderate SUI. These studies indicate that ES may ameliorate damage to the pudendal nerve and thus achieve the goal of SUI treatment, although the mechanism of action of this treatment remains unclear. Therefore, the purpose of the present study was to clarify the relationships among ES, neural cells and Schwann cells at the cellular level. We applied ES to nerve cells at 100 mV/mm or 200 mV/mm for 0, 0.5, 1, or 2 h to investigate changes in nerve cell activity. We then co-cultured the nerve cells with Schwann cells to explore the influence of single-culture and co-culture conditions on the nerve cells. Compared to non-ES, ES of the nerve cells increased their activity. Compared to those in single culture, co-cultured nerve cells exhibited an additional increase in activity. We also found that Schwann cell derived exosomes could promote the activity of nerve cells, with glutamate and calcium ions playing a potential role in this process. These results suggest that the mutual regulation of neural cells and Schwann cells plays an important role in the process by which ES ameliorates neurological function, which may provide a basis for subsequent studies.