Nitric oxide differentially affects ERK and Akt in type 1 and type 2 diabetic rats

Human urine kininogenase attenuates balloon-induced intimal hyperplasia in rabbit carotid artery through transforming growth factor β1/Smad2/3 signaling pathway

OBJECTIVE

Effective treatments against restenosis after percutaneous transluminal angioplasty and stenting are largely lacking. Human tissue kallikrein gene transfer has been shown to be able to attenuate neointima formation induced by balloon catheter. As a tissue kallikrein in vivo, human urinary kininogenase (HUK) is widely used to prevent ischemia-reperfusion injury. However, the effects of HUK on neointima formation have not been explored. We therefore investigated whether HUK could alleviate balloon catheter-induced intimal hyperplasia in rabbits fed with high-fat diets.

METHODS

The effects of HUK on neointima and atherosclerosis formation were analyzed by hematoxylin-eosin staining and immunohistochemical staining in balloon-injured carotid arteries of rabbits. Local inflammatory response was evaluated by detecting the gene expression of tumor necrosis factor α and interleukin 1β with real-time quantitative polymerase chain reaction plus the invasion of macrophages with immunohistochemical staining. Western blotting was employed to investigate the effects of HUK on activities of endothelial nitric oxide synthase (eNOS), transforming growth factor β1 (TGF-β1), and Smad signaling pathway. The long-term effect of HUK on intimal hyperplasia of the injured carotid artery was assessed by angiography.

RESULTS

Quantitative image analysis showed that intravenous administration of HUK for 14 days significantly decreased the intimal areas and intima area/media area ratios (day 14, 54% decrease in intimal area and 58% decrease in intima area/media area ratios; day 28, 63% and 85%). Significant decreases were also noted in macrophage foam cell-positive area after 7-day or 14-day administration of HUK (day 7, 69% decrease in intimal area and 78% decrease in media area; day 14, 79% and 60%; day 28, 68% and 44%). Actin staining for smooth muscle cells in neointima at 2 months showed similar results (vascular smooth muscle cell-positive area of neointima, 28.21% ± 5.58% vs 43.78% ± 8.36%; P < .05). Real-time quantitative polymerase chain reaction or Western blot analysis showed that HUK reduced expression of tumor necrosis factor α, interleukin 1β, TGF-β1, and p-Smad2/3 but increased the expression of p-eNOS. Angiography analysis showed that 14-day administration of HUK significantly decreased the degree of stenosis (26.8% ± 7.1% vs 47.9% ± 5.7%; P < .01) at 2 months after balloon injury.

CONCLUSIONS

Our results indicate that HUK is able to attenuate atherosclerosis formation and to inhibit intimal hyperplasia by downregulating TGF-β1 expression and Smad2/3 phosphorylation, upregulating eNOS activity. HUK may be a potential therapeutic agent to prevent stenosis after vascular injury.

Nitric oxide affects UbcH10 levels differently in type 1 and type 2 diabetic rats

BACKGROUND

Nitric oxide (NO) more effectively inhibits neointimal hyperplasia in type 2 diabetic versus nondiabetic and type 1 diabetic rodents. NO also decreases the ubiquitin-conjugating enzyme UbcH10, which is critical to cell-cycle regulation. This study seeks to determine whether UbcH10 levels in the vasculature of diabetic animal models account for the differential efficacy of NO at inhibiting neointimal hyperplasia.

MATERIALS AND METHODS

Vascular smooth muscle cells (VSMCs) harvested from nondiabetic lean Zucker (LZ) and type 2 diabetic Zucker diabetic fatty (ZDF) rats were exposed to high glucose (25 mM) and high insulin (24 nM) conditions to mimic the diabetic environment in vitro. LZ, streptozotocin-injected LZ (STZ, type 1 diabetic), and ZDF rats underwent carotid artery balloon injury (±10 mg PROLI/NO), and vessels were harvested at 3 and 14 d. UbcH10 was assessed by Western blotting and immunofluorescent staining.

RESULTS

NO more effectively reduced UbcH10 levels in LZ versus ZDF VSMCs; however, addition of insulin and glucose dramatically potentiated the inhibitory effect of NO on UbcH10 in ZDF VSMCs. Three days after balloon injury, Western blotting showed NO decreased free UbcH10 and increased polyubiquitinated UbcH10 levels by 35% in both STZ and ZDF animals. Fourteen days after injury, immunofluorescent staining showed increased UbcH10 levels throughout the arterial wall in all animal models. NO decreased UbcH10 levels in LZ and STZ rats but not in ZDF.

CONCLUSIONS

These data suggest a disconnect between UbcH10 levels and neointimal hyperplasia formation in type 2 diabetic models and contribute valuable insight regarding differential efficacy of NO in these models.