Effects of a gamma-secretase inhibitor of notch signalling on transforming growth factor β1-induced urethral fibrosis

Gamma-Secretase Inhibitors Downregulate the Profibrotic NOTCH Signaling Pathway in Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare skin fragility disorder caused by mutations in COL7A1. RDEB is hallmarked by trauma-induced unremitting blistering, chronic wounds with inflammation, and progressive fibrosis, leading to severe disease complications. There is currently no cure for RDEB-associated fibrosis. Our previous studies and increasing evidence highlighted the profibrotic role of NOTCH pathway in different skin disorders, including RDEB. In this study, we further investigated the role of NOTCH signaling in RDEB pathogenesis and explored the effects of its inhibition by γ-secretase inhibitors DAPT and PF-03084014 (nirogacestat). Our analyses demonstrated that JAG1 and cleaved NOTCH1 are upregulated in primary RDEB fibroblasts (ie, RDEB-derived fibroblasts) compared with controls, and their protein levels are further increased by TGF-β1 stimulation. Functional assays unveiled the involvement of JAG1/NOTCH1 axis in RDEB fibrosis and demonstrated that its blockade counteracts a variety of fibrotic traits. In particular, RDEB-derived fibroblasts treated with PF-03084014 showed (i) a significant reduction of contractility, (ii) a diminished secretion of TGF-β1 and collagens, and (iii) the downregulation of several fibrotic proteins. Although less marked than PF-03084014-treated cells, RDEB-derived fibroblasts exhibited a reduction of fibrotic traits also upon DAPT treatment. This study provides potential therapeutic strategies to antagonize RDEB fibrosis onset and progression.

Pharmacotherapy of urethral stricture

Urethral stricture is characterized by the chronic formation of fibrous tissue, leading to the narrowing of the urethral lumen. Despite the availability of various endoscopic treatments, the recurrence of urethral strictures remains a common challenge. Postsurgery pharmacotherapy targeting tissue fibrosis is a promising option for reducing recurrence rates. Although drugs cannot replace surgery, they can be used as adjuvant therapies to improve outcomes. In this regard, many drugs have been proposed based on the mechanisms underlying the pathophysiology of urethral stricture. Ongoing studies have obtained substantial progress in treating urethral strictures, highlighting the potential for improved drug effectiveness through appropriate clinical delivery methods. Therefore, this review summarizes the latest researches on the mechanisms related to the pathophysiology of urethral stricture and the drugs to provide a theoretical basis and new insights for the effective use and future advancements in drug therapy for urethral stricture.

DKK1 Ameliorates Myofibroblast Differentiation in Urethral Fibrosis in Vivo and in Vitro by Regulating the Canonical Wnt Pathway

Background: Urethral stricture is a common disorder of the lower urinary tract in men. A complex network of pathways and interactions are involved in the pathogenesis of urethral fibrosis. However, the mechanisms underlying urethral fibrosis remain poorly understood. Objectives: To investigate the critical role of the canonical Wnt pathway in development of urethral fibrosis and explore DKK1, the endogenous inhibitor of Wnt pathway, as a potential target to prevent urethral fibrosis in vitro and in vivo. Methods: Urethral fibrosis tissue derived from patients and rat models were harvested to assess the activation of the canonical Wnt pathway by using western blot, qRT-PCR and immunohistochemistryWe performed histological staining, western blot, qRT-PCR and immunohistochemistry to examine the effects of DKK1 treatment on in vivo rat urethral fibrosis models. In vitro, human urethral fibroblasts (HUFs) were cultured to examine the effects of DKK1 in TGFβ1-induced HUFs by CCK-8 assay, hydroxyproline assay, flow cytometry, cell migration assay, western blot, qRT-PCR and immunofluorescence. Results: The key components of Wnt signaling were upregulated in urethral fibrosis tissue derived from patients and rat models while DKK 1 was downregulated. DKK1 ameliorated TGFβ1-induced urethral fibrosis in rats. TGFβ1 induced myofibroblast differentiation by upregulating collagen I, collagen III, α-SMA, β-catenin and p-GSK-3β, while DKK1 was decreased. DKK1 significantly inhibited cell proliferation, collagen content, cell migration and promoted cell apoptosis in TGFβ1-induced HUFs. DKK1 significantly suppressed myofibroblast differentiation of TGFβ1-induced HUFs by downregulating collagen I, collagen III, α-SMA, β-catenin and p-GSK-3β with a mechanism independent of Smad2/3. Conclusions: Our study demonstrated that canonical Wnt pathway may be an essential mechanism underlying the pathogenesis of urethral fibrosis and explored the potential role of DKK1 participation in the development of urethral fibrosis.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

Resveratrol plays an anti-fibrotic and anti-autophagy role by stimulating miR-192-5p expression in urethral fibrosis

BACKGROUND

Resveratrol (RSV) exerts anti-fibrotic effects on various fibrotic diseases. Whereas the biological role of RSV on urethral fibrosis remains to be elucidated. This study aimed to determine the mechanisms by which RSV affects urethral fibrosis and autophagy.

METHODS

Sprague‒Dawley rats and primary fibroblasts were treated with transforming growth factor-β1 (TGFβ1) to generate in vivo and in vitro fibrosis models. Then, those were treated with RSV, and autophagy and fibrosis-related indicators were tested.

RESULTS

Firstly, we found that RSV reversed the upregulation of indicators related to TGFβ1-induced fibrosis (TGFβ1, α-smooth muscle actin, collagen type I, and collagen type III), autophagy (TFEB and LC3), and TGFβR1/Smad4 pathway, as well as the downregulation of p62 and miR-192-5p expression both in vivo and in vitro. Overexpression of miR-192-5p suppressed the upregulation of fibrosis-related markers expression, as well as TFEB and LC3 expression, induced by TGFβ1, while the expression trend of p62 was the opposite. Inhibiting miR-192-5p reversed the effects of RSV on the model group cells. It was also shown that RSV combined with sh-Smad4 inhibited autophagy more effectively than RSV alone.

CONCLUSION

These results suggest that RSV inhibits urinary fibrosis and autophagy via the miR-192-5p/TGFβR1/Smad4 pathway. RAV may be a potential drug for alleviating urethral fibrosis.

The effect of intraurethral heparin on inflammation and spongiofibrosis in a rat model of experimentally induced urethral trauma

AIM

To determine the effect of heparin administered during the early post urethral trauma period on inflammation and spongiofibrosis in rats.

MATERIALS AND METHODS

The study included 24 male rats that were randomized into 3 groups of 8 each. The urethra was traumatized using a 24-G needle sheath in all rats. Group 1 (control group) received intraurethral saline 0.9% injected b.i.d. for 27 days, group 2 received intraurethral Na-heparin (liquemine-Roche) 1500 IU kg^-1 injected b.i.d. for 27 days, and group 3 received intraurethral Na-heparin 1500 IU kg^-1 injected b.i.d and saline 0.9% s.i.d. for 27 days. On day 28 the rats' penises were degloved and penectomy was performed. Inflammation, spongiofibrosis, and congestion in the urethra were investigated in each group.

RESULTS

A statistically significant difference was found between the three groups (control, heparin, and heparin + saline) in the histopathological status of spongiofibrosis, inflammation, and congestion, respectively (P = 0.0001, P = 0.002, P = 0.0001). Severe spongiofibrosis was observed in six (75%) of the rats in group 1 (control group), whereas severe spongiofibrosis was not observed in group 2 (heparin) or group 3 (heparin + saline).

CONCLUSION

We observed that intraurethral Na-heparin 1500 IU kg^-1 injectioned during the early posturethral trauma period in rats significantly decreased inflammation, spongiofibrosis, and congestion.