Carnosol as a Nrf2 Activator Improves Endothelial Barrier Function Through Antioxidative Mechanisms

Area of Science:

• Biochemistry
• Cell Biology
• Pharmacology

Background:

• Diabetic microangiopathy is primarily caused by oxidative stress, leading to damage in microvascular endothelial cells and compromising the vascular barrier.
• Oxidative stress contributes to the pathogenesis of microvascular complications in diabetes, necessitating therapeutic interventions.
• Understanding the protective mechanisms against oxidative stress in endothelial cells is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the protective effects of carnosol against oxidative stress in human microvascular endothelial cells (HMVECs).
• To elucidate the underlying antioxidative mechanisms of carnosol, including its impact on cellular viability, barrier integrity, and key signaling pathways.
• To evaluate the therapeutic potential of carnosol for microvascular endothelial cell injury.

Main Methods:

• Assessed carnosol's antioxidant activity by measuring its effects on cell viability, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production, and nitric oxide (NO) generation.
• Evaluated carnosol's impact on vascular barrier integrity by examining the protein expression of vascular endothelial cadherin (VE-cadherin).
• Investigated carnosol's molecular mechanisms by assessing its effects on Nrf2-Keap1 interaction, antioxidant-responsive element (ARE) activity, heme oxygenase 1 (HO-1), nuclear factor-erythroid 2 related factor 2 (Nrf2), and endothelial nitric oxide synthase (eNOS) expression.

Main Results:

• Carnosol pretreatment significantly suppressed tert-butyl hydroperoxide (t-BHP)-induced decreases in HMVEC viability and LDH production.
• Carnosol reduced ROS production and increased nitric oxide (NO) production in stressed HMVECs.
• Carnosol enhanced VE-cadherin expression, preserving intercellular junction integrity and protecting the microvascular barrier against oxidative stress.
• Carnosol interrupted Nrf2-Keap1 interaction, stimulated ARE-driven luciferase activity, and promoted the expression of HO-1, Nrf2, and eNOS.

Conclusions:

• Carnosol exhibits significant protective effects on human microvascular endothelial cells against oxidative stress through potent antioxidative mechanisms.
• The compound enhances vascular barrier integrity and promotes the expression of key proteins involved in cellular defense and NO synthesis.
• These findings suggest that carnosol holds considerable therapeutic potential for treating microvascular endothelial cell injury, particularly in the context of diabetic complications.