Cyclooxygenase-2 inhibitor ameliorates ureteric damage in rats with obstructed uropathy

Administration of a combination of COX-2/TGF-β1 siRNAs induces hypertrophic scar fibroblast apoptosis through a TP53 mediated caspase pathway

Hypertrophic scar (HTS) formation is a pathological fibrotic skin disease, with no satisfactory treatments available currently. Inducing apoptosis of HTS-derived fibroblasts (HSFs) are becoming promising approaches. In this research, we aim to improve the technology with co-delivery COX-2 and TGF-β1 siRNAs and further investigate the underlying mechanism. Firstly, the HSFs were transfected with 1 µg/ml COX-2 and/or TGF-β1 siRNAs, and proved that the apoptosis of HSFs was greater induced by COX-2/TGF-β1 siRNAs than either COX-2 or TGF-β1 siRNA alone by flow cytometry. To investigate the impact of co-silencing TGF-β1 and COX-2 mRNA expression in vivo, we established HTSs model in rat tails. Our results confirmed that co-silencing of TGF-β1 and COX-2 mRNA expression could significantly alleviate the HTS formation in vivo. Furthermore, we explored the potential molecular mechanism and revealed that the protein levels of TP53, Bcl-2 and Caspase-3 were downregulated while Bax and Cleaved Caspase-3 were upregulated in the COX-2/TGF-β1 siRNA groups compared with HKP group. Taken together, our results demonstrated that simultaneous silencing of COX-2 and TGF-β1 expression by siRNAs induced HSF apoptosis through a TP53 mediated caspase pathway. Therefore, COX-2/TGF-β1 siRNAs might serve as a novel and effective therapeutic alternative for HTSs treatments.

Macrophage-secreted TGF-β1 contributes to fibroblast activation and ureteral stricture after ablation injury

Iatrogenic injury to the healthy ureter during ureteroscope-guided ablation of malignant or nonmalignant disease can result in ureteral stricture. Transforming growth factor (TGF)-β1-mediated scar formation is considered to underlie ureteral stricture, but the cellular sources of this cytokine and the sequelae preceding iatrogenic stricture formation are unknown. Using a swine model of ureteral injury with irreversible electroporation (IRE), we evaluated the cellular sources of TGF-β1 and scar formation at the site of injury and examined in vitro whether the effects of TGF-β1 could be attenuated by pirfenidone. We observed that proliferation and α-smooth muscle actin expression by fibroblasts were restricted to injured tissue and coincided with proliferation of macrophages. Collagen deposition and scarring of the ureter were associated with increased TGF-β1 expression in both fibroblasts and macrophages. Using in vitro experiments, we demonstrated that macrophages stimulated by cells that were killed with IRE, but not LPS, secreted TGF-β1, consistent with a wound healing phenotype. Furthermore, using 3T3 fibroblasts, we demonstrated that stimulation with paracrine TGF-β1 is necessary and sufficient to promote differentiation of fibroblasts and increase collagen secretion. In vitro, we also showed that treatment with pirfenidone, which modulates TGF-β1 activity, limits proliferation and TGF-β1 secretion in macrophages and scar formation-related activity by fibroblasts. In conclusion, we identified wound healing-related macrophages to be an important source of TGF-β1 in the injured ureter, which may be a paracrine source of TGF-β1 driving scar formation by fibroblasts, resulting in stricture formation.

Ureteral Access Sheath Influence on the Ureteral Wall Evaluated by Cyclooxygenase-2 and Tumor Necrosis Factor-α in a Porcine Model

Objective: To examine the effect of ureteral access sheath (UAS) on the expression of the pro-inflammatory mediators cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) in the ureteral wall.

Material and Methods: In 22 pigs an UAS was inserted and removed after 2 minutes on one side and 2 hours on the contralateral side. Postoperatively ureters were excised in vivo, and tissue samples from the distal (2 minutes/2 hours) and proximal ureter (2 minutes/2 hours) were snap-frozen before quantitative polymerase chain reaction analysis of COX-2 and TNF-α. Five unmanipulated ureteral units from other pigs served as the control group.

Results: Compared to controls COX-2 mRNA was significantly upregulated in all UAS treated ureteral groups. Similarly, TNF-α mRNA was upregulated in all groups except the 2-minute proximal ureteral group. Both COX-2 and TNF-α expression were significantly higher in the distal than in the proximal ureter in the UAS treated ureters. After UAS insertion for 2 minutes, expression levels in the distal ureter were increased 6.5- and 8-fold for COX-2 and TNF-α, respectively; and after 2 hours of UAS placement COX-2 and TNF-α mRNA expression levels were increased 9- and 9.5-fold, respectively.

Conclusion: The pro-inflammatory mediators COX-2 and TNF-α were significantly upregulated in the ureteral wall by the influence of UAS. These findings may have implications for postoperative pain, drainage, and complications.

PI3K mediates stretch-induced COX-2 expression during urinary tract obstruction

BACKGROUND AND PURPOSE

Stretch-induced cyclooxygenase-2 (COX-2) expression occurs in urothelial cells during urinary tract obstruction (UTO). This increases COX-2-dependent prostanoid synthesis in stretched urothelial cells. These prostanoids then act on afferent neurons and smooth muscle cells in the ureter to amplify nociceptive and contractile responses, respectively. We previously used a unilateral ureteral obstruction (UUO) mouse model and a primary human urothelial cell (HUC) stretch model to describe ureteral COX-2 expression during UTO. The current study was performed to determine whether phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathways are necessary for stretch-induced COX-2 expression in urothelial cells.

MATERIALS AND METHODS

Adult male CD-1 mice were treated with 25% dimethyl sulfoxide/phosphate buffered saline or PI3K inhibitor LY294002 (3 mg/kg, 30 mg/kg) for 1 hour before performing UUO for up to 4 hours. Obstructed and contralateral mouse ureters were analyzed via immunohistochemistry or Western blotting to assess in vivo stretch-induced COX-2 expression. In addition, HUCs were cyclically stretched (5%-20% displacement, 12 cycles/min) on collagen I-coated stretch plates and assessed for COX-2 expression via Western blotting.

RESULTS

Histologic analyses of obstructed ureters show that urothelial cells stretch in response to external obstruction, COX-2 expression increases in the stretched urothelial cells, and no infiltrating immune cells were present under the conditions of the study. PI3K inhibitor LY294002 (30 mg/kg) attenuated in vivo stretch-induced COX-2 expression. LY294002 or RNA-interference also attenuated (HUC) stretch-induced COX-2 expression in vitro. Furthermore, the results also show that LY294002 inhibits stretch-induced protein kinase C (PKCζ) activation previously identified upstream of stretch-induced COX-2 expression in HUCs.

CONCLUSIONS

The results indicate that PI3K is a mediator of stretch-induced COX-2 expression in urothelial cells. Identifying molecules that couple urothelial cell stretch to COX-2 expression may provide targets of drug action for effective therapeutics for UTO.

Atorvastatin ameliorates tissue damage of obstructed ureter in rats

AIMS

To investigate the effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor on the tissue damage and fibrosis of obstructed ureters, 80 rats were studied.

MAIN METHODS

Atorvastatin, a HMG-CoA reductase inhibitor, was administered to 40 rats at the dose of 20 mg/kg per day 1day before unilateral ligation of ureters and every day thereafter. The other rats served as controls. Eight rats from each group were sacrificed for examination on days 7, 14, 21, 28 and 42 after ligation, respectively. The expressions of transforming growth factor-β1 (TGF-β1), Interleukine-1β (IL-1β), Interleukine-6 (IL-6), tumor necrosis factor-alpha (TNF-α), proliferation cell nuclear antigen (PCNA), and the apoptotic cells in the ureteric smooth muscle were examined.

KEY FINDINGS

Hydroureter and fibrosis of the muscle layer became progressively aggravated in the ligated ureters of the atorvastatin-treated group and control group. The severities of hydroureter and muscle layer fibrosis in the ligated ureters of the treated group were significantly less than in the control group. The atorvastatin administration also decreased the expression of TGF-β1, IL-1β, IL-6, TNF-α, PCNA and the labeling index of apoptotic cells in the smooth muscle layer of ligated ureters in the treated group.

SIGNIFICANCE

We concluded that atorvastatin might ameliorate the tissue damage of obstructed ureters, at least partially, via the inhibition on TGF-β1) expression and by diminishing the effects of pro-inflammatory cytokines.

uPA is upregulated by high dose celecoxib in women at increased risk of developing breast cancer

Background

While increased urokinase-type plasminogen activator (uPA) expression in breast cancer tissue is directly associated with poor prognosis, recent evidence suggests that uPA overexpression may suppress tumor growth and prolong survival. Celecoxib has been shown to have antiangiogenic and antiproliferative properties. We sought to determine if uPA, PA inhibitor (PAI)-1 and prostaglandin (PG)E₂ expression in nipple aspirate fluid (NAF) and uPA and PGE₂ expression in plasma were altered by celecoxib dose and concentration in women at increased breast cancer risk.

Methods

NAF and plasma samples were collected in women at increased breast cancer risk before and 2 weeks after taking celecoxib 200 or 400 mg twice daily (bid). uPA, PAI-1 and PGE₂ were measured before and after intervention.

Results

Celecoxib concentrations trended higher in women taking 400 mg (median 1025.0 ng/mL) compared to 200 mg bid (median 227.3 ng/mL), and in post- (534.6 ng/mL) compared to premenopausal (227.3 ng/mL) women. In postmenopausal women treated with the higher (400 mg bid) celecoxib dose, uPA concentrations increased, while PAI-1 and PGE₂ decreased. In women taking the higher dose, both PAI-1 (r = -.97, p = .0048) and PGE₂ (r = -.69, p = .019) in NAF and uPA in plasma (r = .45, p = .023) were correlated with celecoxib concentrations.

Conclusion

Celecoxib concentrations after treatment correlate inversely with the change in PAI-1 and PGE₂ in the breast and directly with the change in uPA in the circulation. uPA upregulation, in concert with PAI-1 and PGE₂ downregulation, may have a cancer preventive effect.