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A novel mechanism of action for statins against diabetes-induced oxidative stress
C Vecchione1, M T Gentile, A Aretini
1Department of Angio-cardio-neurology, IRCCS Neuromed, Località Camerelle, 86077, Pozzilli (IS), Italy.
Insights
Atorvastatin reduces oxidative stress and vascular dysfunction in diabetes by inhibiting Rac-1 activation. This mechanism involves a reduction in geranylgeranyl pyrophosphate (GGPP), highlighting Rac-1 as a therapeutic target.
Area of Science:
- Cardiovascular Research
- Endocrinology
- Pharmacology
Background:
- Diabetes mellitus is associated with significant vascular complications, including oxidative stress and endothelial dysfunction.
- Statins, such as atorvastatin, demonstrate beneficial effects on vascular health in diabetic patients, but the precise mechanisms remain unclear.
- The small GTPase Rac-1 plays a critical role in regulating oxidative stress and vascular tone.
Purpose of the Study:
- To investigate the role of Rac-1 in the protective vascular effects of atorvastatin in diabetes.
- To determine if atorvastatin modulates Rac-1 activity and its downstream signaling pathways in the context of high glucose and diabetes-induced vascular dysfunction.
Main Methods:
- Human aortic endothelial cells (HAECs) were exposed to high glucose conditions to mimic the diabetic environment.
- Rac-1 activity was assessed by measuring its translocation to the cell membrane and its association with p21-activated kinase.
- In vivo studies utilized a murine model of diabetes mellitus, assessing vascular function, oxidative stress, and Rac-1 activity in atorvastatin-treated mice.
- Experiments involved manipulating Rac-1 activity using adenoviral vectors expressing constitutively active Rac-1 mutants and assessing the impact of geranylgeranyl pyrophosphate (GGPP).
Main Results:
- Atorvastatin treatment attenuated high glucose-induced oxidative stress and impaired Rac-1 activation in HAECs.
- Similar protective effects and inhibition of Rac-1 activation were observed in atorvastatin-treated diabetic mice.
- Supplementation with GGPP reversed the protective effects of atorvastatin, indicating its crucial role in the mechanism.
- Atorvastatin lost its protective capacity in vessels expressing a constitutively active Rac-1 mutant.
Conclusions:
- The vascular antioxidant and protective effects of atorvastatin in diabetes are mediated by the inhibition of Rac-1.
- This inhibition is linked to a reduction in geranylgeranyl pyrophosphate (GGPP) availability.
- Targeting Rac-1 through selective inhibition presents a promising pharmacological strategy to mitigate vascular complications in diabetes mellitus.
Aims/Hypothesis:
Atorvastatin exerts beneficial vascular effects in diabetes, but the underlying mechanisms are yet to be elucidated. The aim of the present study was to determine whether Rac-1 is involved in the effect of atorvastatin on oxidative stress and vascular dysfunction.
Materials And Methods:
Using human aortic endothelial cells (HAECs) we evaluated the effect of high glucose levels on peroxide production by dihydrodichlorofluorescein and on Rac-1 activity using immunocytochemistry to detect Rac-1 translocation to the membrane. We evaluated vascular function, peroxide production by dihydroethidium and NADPH oxidase activity in vessels from atorvastatin-treated mice. Rac-1 activity was also assessed, both by immunoprecipitation of the Rac-p21-activated kinase complex and by analysis of Rac-1 translocation to the membrane. These experiments were also conducted in vessels infected with an adenoviral vector carrying a constitutively active mutant of Rac-1.
Results:
In HAECs exposed to high glucose levels, atorvastatin prevented oxidative stress, and this protection was associated with impaired Rac-1 activation. This effect was also observed in a murine model of diabetes mellitus. More importantly, the addition of geranylgeranyl pyrophosphate (GGPP) blocked the effects of atorvastatin in both glucose-exposed HAECs and diabetic vessels. Atorvastatin failed to afford protection against vascular abnormalities in the presence of a constitutively active mutant of Rac-1.
Conclusions/Interpretation:
The results of this study demonstrate that the vascular antioxidant effect of atorvastatin in diabetes is mediated through inhibition of Rac-1 via a reduction in GGPP. Thus, selective Rac-1 inhibition should be considered in the design of novel pharmacological strategies to reduce the impact of diabetes mellitus on vascular function.
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