Suppressive Effects of Hydroxytyrosol on Oxidative Stress and Nuclear Factor-κB Activation in THP-1 Cells

Abstract

Recent publications have shown that an oxidized cytosolic environment amplifies activation of nuclear factor kappaB (NF-kB), which plays a critical role during inflammatory processes by activating many genes encoding for proinflammatory cytokines and immunoregulatory mediators.1) Some publications have also suggested that reactive oxygen species (ROS) influence inflammatory processes through mechanisms that are dependent on NF-kB.2) In the course of many inflammatory diseases reduced levels of glutathione (GSH) and/or increased levels of free radicals have been detected, 3,4) indicating the involvement of oxidative stress.Hydroxytyrosol (HT), present in the phenolic fraction of virgin olive oil in a concentration range of 10-300 ppm, is abundant in naturally fermented table olives and can be also recovered from virgin olive oil by-products. 5) At nutritionally relevant concentrations, HT possesses marked antioxidant activity and is a good radical scavenger.6,7) HT in vitro prevents protein damage in melanoma cells by ROS induced by long-wave ultraviolet light 8) and DNA damage in Jurkat cells exposed to hydrogen peroxide (H 2 O 2 ).9) Preincubation of intestinal Caco-2 cells with HT prevents the typical damages of oxidative stress. 10) Similarly, HT exerts protective effects against H 2 O 2 -induced oxidative hemolysis and malondialdehyde (MDA) formation in red blood cells.11) It also exerts inhibitory effects on GSH depletion induced by tert-butylhydroperoxide (t-BHP) in HepG2 cells.12) However, little information is available about the effects of HT on oxidative stress and NF-kB activation in LPS-stimulated THP-1 cells. In this study we assessed supression by HT of nitric oxide (NO), ROS, NF-kB activation, and the increase of GSH contents in lipopolysaccharide (LPS)-stimulated THP-1 cells. MATERIALS AND METHODS ChemicalsThe sample of HT was supplied by Eisai Food & Chemical Co., Ltd., Japan. LPS (Escherichia coli LPS, serotype 0127:B8), and 2Ј,7Ј-dichlorofluorescein diacetate (DCFH-DA) were purchased from Sigma (St. Louis, MO, U.S.A.).Cell Culture and Treatment Human monocytic THP-1 cells (American Type Culture Collection, Manassas, VA, U.S.A.) were obtained from Peking Union Medical College (Peking, China) and cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum (Gibco), penicillin (100 U/ml; Gibco), and streptomycin (100 mg/ml; Gibco) at 37°C in a 5% CO 2 -humidified incubator. The cells were treated with or without the indicated concentrations of HT (25, 50, 100 mM) or N-acetylcysteine (NAC) (2.5 mM) for 10 min then incubated with LPS (1.0 mg/ml) for 3 h.Measurement of ROS Intracellular ROS production was measured using DCFH-DA by the method of Bass and coworkers, 13) with some modification. DCFH-DA penetrates the cells and is hydrolyzed by intracellular esterases to the nonfluorescent DCFH, which can be rapidly oxidized to the highly fluorescent 2,7-dichlorofluorescein (DCF) in the presence of ROS. THP-1 monocytes were inoculated into sixwell plates; the numbers of cells were 2ϫ10 5 cells/...

3,4-Dihydroxyphenylethanol alleviates early brain injury by modulating oxidative stress and Akt and nuclear factor-κB pathways in a rat model of subarachnoid hemorrhage

“…In the present study, the administration of DOPET restrained NF-κB protein expression following SAH. This is consistent with a study conducted by Zhang et al (38), which suggested that treatment with DOPET significantly suppressed NF-κB expression in THP-1 cells. These results support the implication of the Akt/NF-κB pathway in the neuroprotective effect of DOPET in the EBI after SAH.…”

Olive oil and its phenolic compounds (hydroxytyrosol and tyrosol) ameliorated TCDD-induced heptotoxicity in rats via inhibition of oxidative stress and apoptosis

“…In this study, we found that OO, HT, and TY co-treated animals showed resistance to the production of NO on TCDD treatment, implying that these compounds could prevent or be helpful in reducing the complications of TCDD-induced oxidative stress. Substantial evidence in the literature shows that the olive oil phenolic compound HT treatment suppresses the activation of NF-kB and attenuate oxidative stress in THP-1 cells by decreasing NO production (Zhang et al, 2009). …”

B-Cell Lymphoma-2 Over-Expression Protects .DELTA.-Elemene-Induced Apoptosis in Human Lung Carcinoma Mucoepidermoid Cells via a Nuclear Factor Kappa B-Related Pathway

“…[10][11][12][13][14]16,17) In order to determine how the over-expression of Bcl-2 and Bcl-xL affects the NF-kappa B activity in NCI-H292 cells treated either d-elemene or b-elemene, the cells transfected with either Bcl-2 or Bcl-xL were incubated with 200 mM of d-elemene or b-elemene or vehicles. The nuclear protein was isolated after incubation.…”

“…[12][13][14][15][16] Inducible loss of NF-kappa B activity is associated with the down-regulation of anti-apoptotic Bcl-2 family members and the occurence of apoptosis. Furthermore, the promoter regions of both Bcl-2 and Bcl-xL genes contain binding sites for NF-kappa B.…”