Asiaticoside Attenuates Cell Growth Inhibition and Apoptosis Induced by A beta(1-42) via Inhibiting the TLR4/NF-kappa B Signaling Pathway in Human Brain Microvascular Endothelial Cells

作者：Song Daqiang; Jiang Xian; Liu Yiliu; Sun Yuhong; Cao Shousong^*; Zhang Zhuo^*

来源：Frontiers in Pharmacology, 2018, 9: 28.

DOI：10.3389/fphar.2018.00028

• Alzheimer's disease
• asiaticoside
• human brain microvascular endothelial cells (hBMECs)
• A beta(1-42)
• TLR4
• NF-kappa B

Alzheimer's disease (AD) is a very common progressive neurodegenerative disorder with the highest incidence in the world. Dysfunction of the blood-brain barrier (BBB) may be responsible for the pathogenesis and pathology of AD for abnormally transporting amyloid-beta (A beta, the main component of the senile plaques) from the sera into the central nervous system. A beta peptides induce apoptosis in human brain microvascular endothelial cells (hBMECs), the main component of BBB. Apoptosis in neuronal cells plays a critical role in the pathogenesis of AD. Asiaticoside, a natural glycoside extracted from Centella asiatica (L.) Urban, has an anti-apoptotic effect on hBMECs but the molecule mechanism remains unclear. Therefore, we investigate the protective effect of asiaticoside on A beta(1-42)-induced cytotoxicity and apoptosis as well as associated mechanism in hBMECs with commonly used in vitro methods for clinical development of asiaticoside as a novel anti-AD agent. In the present study, we investigated the effects of asiaticoside on cytotoxicity by Cell Counting Kit-8 assay, mitochondrial membrane potential by JC-1 fluorescence analysis, anti-apoptosis by Hoechst 33258 staining and Annexin V-FITC (fluorescein isothiocyanate) and propidium iodide (PI) analyses, the expressions of TNF-alpha and IL-6 by enzyme-linked immunosorbent assay (ELISA) and TLR4, MyD88, TRAF6, p-NF-kappa B p65, and total NF-kappa B p65 by Western blotting, and nuclear translocation of NF-kappa B p65 by immunofluorescence analysis in hBMECs. The results showed that pretreatment of asiaticoside (25, 50, and 100 mu M) for 12 h significantly attenuated cell growth inhibition and apoptosis, and restored declined mitochondrial membrane potential induced by A beta(1-42) (50 mu M) in hBMECs. Asiaticoside also significantly downregulated the elevated expressions of TNF-alpha, IL-6, TLR4, MyD88, TRAF6, and p-NF-kappa B p65, as well as inhibited NF-kappa B p65 translocation from cytoplasm to nucleus induced by A beta(1-42) in hBMECs in a concentration-dependent manner. The possible underlying molecular mechanism of asiaticoside may be through inhibiting the TLR4/NF-kappa B signaling pathway. Therefore, asiaticoside may be developed as a novel agent for the prevention and/or treatment of AD clinically.

• 出版日期2018-1-30