[Pirfenidone alleviates urethral stricture following urethral injury in rats by suppressing TGF-β1 signaling and inflammatory response]

OBJECTIVE

To investigate the effect of pirfenidone for reducing urethral stricture following urethral injury in rats and explore the possible mechanism.

METHODS

Thirty male SD rats were randomly assigned into negative control group, positive control group and pirfenidone group (n=10). In pirfenidone and positive control groups, the rats were subjected to incision of the posterior urethral cavernous body followed by daily intraperitoneal injection of pirfenidone (100 mg/kg) and an equivalent volume of solvent, respectively. The rats in the negative control group were given intraperitoneal injections of solvent without urethral injury. At two weeks after modeling, retrograde urethrography was performed for observing urethral stricture, and the injured urethral tissues were harvested for HE staining, Masson staining, immunohistochemical staining and Western blotting for detecting the protein expressions of α-SMA and TGF-β1. The mRNA expressions of the inflammatory factors TNF-α, IL-6, and IL-1β were detected using qRT-PCR.

RESULTS

The body weight of the rats in pirfenidone group was significantly decreased compared with that in the other two groups (P < 0.05). Retrograde urethrography showed significant narrowing of the urethra in the positive control group but not in the pirfenidone group. HE staining of the injured urethral tissues showed obvious proliferation of urethral epithelial cells with narrow urethral cavity and increased inflammatory cells in positive control group. The pathological findings of the urethra were similar between pirfenidone group and the negative control group. Masson staining revealed obviously reduced collagen fibers and regular arrangement of the fibers in pirfenidone group as compared to the positive control group. Compared with those in the negative control group, the expressions of α-SMA and TGF-β1 were significantly increased in the positive control group, and pirfenidone treatment significantly inhibited their expressions (P < 0.05 or 0.01). Pirfenidone also significantly inhibited the mRNA expressions of TNF-α, IL-6, and IL-1β in the injured urethral tissue (P < 0.05 or 0.01).

CONCLUSION

Pirfenidone can prevent urethral fibrosis and stricture after urethral injury possibly by inhibiting the TGF-β1 pathway and inflammatory response.

A Rho kinase inhibitor (Fasudil) suppresses TGF-β mediated autophagy in urethra fibroblasts to attenuate traumatic urethral stricture (TUS) through re-activating Akt/mTOR pathway: An in vitro study

AIMS

Transforming growth factor-β (TGF-β) mediated super-activation of urethra fibroblasts contributes to the progression of traumatic urethral stricture (TUS), and the Rho-associated kinase inhibitors, Fasudil, might be a novel therapeutic agent for TUS, but the underlying mechanisms had not been studied.

MATERIALS AND METHODS

The primary urethral fibroblasts (PUFs) were isolated from rabbit urethral scar tissues and cultured in vitro, and the PUFs were subsequently treated with TGF-β (10 μg/L) to simulate the realistic conditions of TUS pathogenesis. Next, the PUFs were exposed to Fasudil (50 μM) and autophagy inhibitor 3-methyladenine (3-MA) treatment. Genes expression was examined by Western Blot and immunofluorescence staining, and cellular functions were determined by MTT assay and Transwell assay.

KEY FINDINGS

TGF-β promoted cell proliferation, migration, autophagy, and secretion of extracellular matrix (ECM), including collagen I and collagen III, which were reversed by co-treating cells with both Fasudil and 3-MA. In addition, TGF-β treatment decreased the expression levels of phosphorylated Akt (p-Akt) and mTOR (p-mTOR) to inactivate the Akt/mTOR pathway in the PUFs, which could be re-activated by Fasudil. Then, the fibroblasts were treated with the Pan-Akt inhibitor (GDC-0068), and we surprisingly found that GDC-0068 abrogated the inhibiting effects of Fasudil on cell autophagy and proliferation in the PUFs treated with TGF-β.

SIGNIFICANCE

Fasudil regulated Akt/mTOR pathway mediated autophagy to hamper TGF-β-mediated super-activation in PUFs, which supported that Fasudil might be an ideal candidate therapeutic agent for TUS treatment for clinical utilization.

Moderate and severe fetal pyelectasis: Correlation between prenatal aspects and postnatal outcome

BACKGROUND

Renal pelvic dilatation (RPD) is a frequent finding in fetal ultrasound. The aim of the study is to correlate the prenatally detected moderate and severe pyelectasis with the postnatal outcome.

METHODS

A retrospective analysis involving 90 cases of prenatally detected moderate and severe RPD referred to our prenatal diagnosis centre with 18 months of urological follow-up. Prenatal ultrasound was correlated with postnatal renal function, assessed by plasmatic creatinine and/or renal scintigraphy performed before surgery.

RESULTS

Cases were divided between two groups according to postnatal management: group A including 35 newborns (38.9%) that needed surgical treatment and group B with 55 patients (61.1%) who were managed conservatively. The group A presented higher median RPD (18 mm, IQR 12-25 mm) compared to the group B (11 mm, IQR 10-14 mm). The most common anomaly detected within group A was pelvi-ureteric junction (PUI) obstruction (43%). Within group B 32 cases (58%) showed spontaneous resolution of hydronephrosis during postnatal follow up. In case of moderate pyelectasis the risk of postnatal surgery was 25% and raised to 60% for severe RPD. In our study, 29 newborns showed pathologic scintigraphies: 25 required surgery while 4 did not find indication for surgery due to ipsilateral renal function irreversible damage. 6 patients had high creatinine level (>0.6 mg/dl). 35 cases out of 90 (39%) developed monolateral irreversible renal function impairment.

CONCLUSION

Moderate and severe RPD are often correlated with postnatal renal damage, therefore a close multidisciplinary follow-up is required. Prenatal scanning is highly predictive of postnatal outcome and can address properly the prenatal counseling.

The effect of rapamycin on TGFβ1 and MMP1 expression in a rabbit model of urethral stricture

PURPOSE

To investigate the effect of rapamycin on TGFβ1 and MMP1 expression in a rabbit model of urethral stricture.

METHODS

Twenty-four adult New Zealand male rabbits underwent an electrocoagulation of the bulbar urethra with a 13Fr pediatric resectoscope. Then rabbits were randomly divided into three groups: (1) normal control group: normal saline (NS), (2) the vehicle control group: dimethyl sulfoxide (DMSO), and (3) the treatment group: effective-dose rapamycin in DMSO (Ra), with 12, 6, and 6 rabbits in each group, respectively. Drugs were given by urethral irrigation daily for 4 weeks. Urethral tissue was harvested for histological and molecular analyses. TGFβ1 and MMP1 expression levels were evaluated by real-time quantitative PCR and immunohistochemistry.

RESULTS

Ten, six, and six rabbits were evaluated finally in Ra, DMSO, and NS group, respectively. Histological examination revealed the distribution of fibrosis and the degree of collagen deposition in the Ra group were smaller and slighter than the two control groups. Collagen content was significantly less in the Ra group than in the DMSO group (P < 0.001) and the NS group (P < 0.001). qRT-PCR analysis showed a higher expression of MMP1 mRNA in the Ra group than in the DMSO group (P < 0.001) and the NS group (P < 0.001). Immunohistochemistry showed the protein levels of MMP1 in the Ra group were significantly increased when compared with the DMSO group (P < 0.01) and the NS group (P < 0.01). On the other hand, no statistical difference could be found between every two groups in both mRNA and protein levels of TGFβ1.

CONCLUSIONS

Rapamycin enhances the expression of MMP1 in a rabbit model of urethral stricture, but has no direct effect on the expression of TGFβ1.

Synthesis and evaluation of long-acting D-penicillamine derivatives

This study extends the use of two lathyrogens, ss-aminopropionitrile (BAPN) and D-penicillamine (DPA) from daily systemic or local-topical administration to long-time acting agents. This was achieved by converting the hydrophilic drugs into lipophilic derivatives. The synthesis of functional derivatives of DPA consisted in esterification with methyl-, hexyl-, or benzyl alcohols in the presence of thionylchloride. The esters formed were hydrochlorides, acidic and soluble in water. During neutralization in vitro or in vivo by tissue fluid, an oily substance is formed that elutes from a hydrogel polymer at a much slower rate than hydroplilic DPA itself. The degree of lipophilicity, measured as a partition coefficient between octanol/water, was highest for hexyl ester and lowest for methyl ester DPA. A single injection of either DPA hexyl ester HCl or 3-hexyl(amino) propionitrile into the full thickness skin incision wound in rats significantly lowered the breaking strength of the wound 12 days after injection, indicating the interference with collagen cross-linking. Both agents injected into the breast adenocarcinoma in Fisher rats significantly inhibited tumor growth without any signs of local or systemic toxicity. We conclude that these lipophilic lathyrogens with prolonged effectiveness are suitable in the treatment of pathologies, consisting of excessively cross-linked or deposited collagen (fibrotic adhesions, strictures, stenosis, and scar contractures) and in the treatment of single, solitary tumors, malignant and benign.

An experimental model for stricture studies in the anterior urethra of the male rabbit

In this study, an animal model was developed for the examination of urethral strictures (US). Through a resectoscope, a resection was made in the urethras of 15 male rabbits. After 30 days, the rabbits were evaluated with urethrography, impedance planimetry and either histology or the determination of collagen content. Fifteen rabbits serving as controls were evaluated in the same way. Three rabbits in the resection group and one in the control group died before evaluation. Urethrography demonstrated a stricture in the remaining 12 animals in the resection group. The urethras of the control animals were all normal. Impedance planimetry confirmed that the luminal cross sectional area (CSA) of the strictures was significantly smaller than the CSA of the corresponding part of the urethra in the control group. No difference in CSA was found 1 cm proximal to the stricture. The strictures consisted of densely woven collagen which sent tongues into the adjacent normal parts of the urethra. No difference in collagen content was found between the two groups either at the stricture site or 1 cm proximally. The described method of producing US in the rabbit model was very consistent with all operated animals developing a stricture. The model might prove valuable in evaluating new methods for the treatment of US.

Immunohistochemical and molecular analysis in recurrent urethral stricture

The authors have analyzed the most recent additions to the literature of immunohistochemical and molecular assessment of acquired urethral strictures and report on their data obtained in a selected clinical series. Innovative immunohistochemical studies in patients presenting with plurirecurrent symptoms suggest that urethral mesenchymal changes caused by tissue de-epithelialization may be the underlying cause of stricture. This condition may be congenital or acquired. It may determine aberrant connective tissue formation induced by abnormal fibroblastic activation with formation of over abundant hyperdense collagen scar tissue.

Biochemical characterization and quantitation of the collagenous components of urethral stricture tissue

The collagenous composition of normal and strictured human urethral tissue was analyzed qualitatively by immunohistochemistry and quantitatively by 2-dimensional gel electrophoresis of cyanogen bromide digested tissue. Histological comparison of the normal and strictured urethral tissue showed that the normal urethral spongiosum was replaced by densely packed connective tissue fibers interspersed with fibroblasts in the strictured tissue. The immunohistochemical analysis of urethral tissue identified the presence of types I and III collagen fibers in normal spongiosum and in the connective tissue scar of strictured tissue. Estimation of the collagen type III:I ratio using scanning densitometry revealed a CB5:CB8 peptide ratio of 0.357 +/- 0.058 in the normal tissue, while the urethral stricture tissue had a CB5:CB8 ratio of 0.203 +/- 0.079 (p = 0.010). Total collagen content, as determined by hydroxyproline analysis, revealed no statistically significant differences between control and strictured tissue. Therefore, the normal urethral spongiosum was comprised of 75.1% type I collagen and 24.9% type III collagen. In contrast, the type I collagen in urethral stricture tissue was increased (83.9%), with a corresponding decrease in type III collagen (16.1%). This alteration in the ratio of collagen type III:I may explain the fibrotic noncompliant nature of urethral stricture scar tissue.