Asiatic acid stabilizes cytoskeletal proteins and prevents TNF-α-induced disorganization of cell-cell junctions in human aortic endothelial cells

Abstract

Endothelial hyperpermeability represents an initiating step in early atherosclerosis and it often occurs as a result of endothelial barrier dysfunction. Asiatic acid, a major triterpene isolated from Centella asiatica (L.) Urban, has previously been demonstrated to protect against tumor necrosis factor (TNF)-α-induced endothelial barrier dysfunction. The present study aimed to investigate the mechanisms underlying the barrier protective effect of asiatic acid in human aortic endothelial cells (HAECs). The localization of F-actin, diphosphorylated myosin light chain (diphospho-MLC), adherens junctions (AJs) and tight junctions (TJs) was studied using immunocytochemistry techniques and confocal microscopy. Their total protein expressions were examined using western blot analysis. The endothelial permeability was assessed using In Vitro Vascular Permeability Assay kits. In addition, intracellular redistribution of the junctional proteins was evaluated using subcellular fractionation kits. We show that asiatic acid stabilized F-actin and diphospho-MLC at the cell periphery and prevented their rearrangement stimulated by TNF-α. However, asiatic acid failed to attenuate cytochalasin D-induced increased permeability. Besides, asiatic acid abrogated TNF-α-induced structural reorganization of vascular endothelial (VE)-cadherin and β-catenin by preserving their reticulum structures at cell-cell contact areas. In addition, asiatic acid also inhibited TNF-α-induced redistribution of occludin and zona occludens (ZO)-1 in different subcellular fractions. In conclusion, the barrier-stabilizing effect of asiatic acid might be associated with preservation of AJs and prevention of TJ redistribution caused by TNF-α. This study provides evidence to support the potential use of asiatic acid in the prevention of early atherosclerosis, which is initiated by endothelial barrier dysfunction.

Therapeutic Potential of Centella asiatica and Its Triterpenes: A Review

“…A cell experiment found that asiatic acid reduced atherosclerosis by inhibiting the redistribution of occludin and zona occludens -1 (ZO-1). Furthermore, it decreased F-actin rearrangement and myosin light chain (MLC)dephosphorylation (Fong et al, 2019). Clinical studies have shown that after 4 years of intervention in patients with Pycnogenol ® 100 mg/day plus C. asiatica (100 mg/ day), the combined treatment group has reduced plaque progression, reduced oxidative stress, and mild transient brain deficiency as compared to the control group.…”

Combined Extract of Vitis vinifera L. and Centella asiatica Synergistically Attenuates Oxidative Damage Induced by Hydrogen Peroxide in Human Umbilical Vein Endothelial Cells

“…In another study, the major compound of VE, quercetin 3-glucuronide, was shown to inhibit ROS generation and lipid peroxidation by increasing the activities of antioxidant enzymes, such as SOD and CAT, by upregulating heme oxygenase-1 via the transcription factors nuclear factor E2-related factor 2 and activator protein-1 ( Lee et al, 2017 ). In the case of C. asiatica , the major active compounds asiaticoside and asiatic acid protect against TNF-a-induced endothelial barrier dysfunction by abrogating the structural reorganization of occludin, ZO- 1, and adherens junction proteins, such as VE-cadherin and β-catenin ( Fong et al, 2015 ; Fong et al, 2019 ). Furthermore, madecassoside, another active constituent, inhibits p38 MAPK activity induced by H 2 O 2 in HUVECs ( Bian et al, 2012 ).…”

Malaysian Tualang Honey Inhibits Hydrogen Peroxide-Induced Endothelial Hyperpermeability

“…The immunofluorescence staining of filamentous actin (F-actin) was conducted according to the methods reported previously [15]. Briefly, HUVECs were cultured on fibronectin-coated round coverslips at 1.5 × 10 5 cells/well for 4 d at 37°C to reach confluence.…”