Rhein from Rheum rhabarbarum Inhibits Hydrogen-Peroxide-Induced Oxidative Stress in Intestinal Epithelial Cells Partly through PI3K/Akt-Mediated Nrf2/HO-1 Pathways

Abstract

Rheum rhabarbarum has been widely used as a herbal medicine and food in China. The objective of this study was to investigate the cytoprotective action and underlying mechanisms of rhein, one active ingredient isolated from R. rhabarbarum, on H2O2-challenged rat small intestine epithelial cells (IEC-6 cells). H2O2-challenged IEC-6 cells were incubated in the pretreatment with or without rhein or LY294002, a PI3K/Akt inhibitor. The cell viability, apoptosis, intracellular reactive oxygen species (ROS), and antioxidants were measured. The expressions of heme oxygenase 1 (HO-1), nuclear factor erythroid 2-related factor (Nrf2), Akt, and p-Akt were evaluated by western blotting. Meanwhile, LY294002 was also used to investigate the role of PI3K/Akt in the rhein-induced cytoprotective role. The results showed that pretreatment of rhein could reverse the inhibition of cell viability and suppress the apoptosis, caspase-3 activity, and intracellular ROS induced by H2O2. Rhein also supported SOD activity catalase activity, glutathione S-transferase activity, and glutathione content. Furthermore, rhein induced the protein expression of HO-1 together with its upstream mediator Nrf2 and activated the phosphorylation of Akt in IEC-6 cells. LY294002 inhibited increased cell viability, upregulated the lowered apoptotic rate, and enhanced the weakened ROS levels. Although the inhibition of PI3K/Akt did not inhibit the Nrf2 nuclear level under 4 μM rhein, LY294002 inhibited the Nrf2 nuclear level under 2 μM rhein and blocked HO-1 expression. These data demonstrated that rhein protected IEC-6 cells against oxidative damage partly via PI3K/Akt and Nrf2/HO-1 pathways.

Curcumin Protects Human Trophoblast HTR8/SVneo Cells from H2O2-Induced Oxidative Stress by Activating Nrf2 Signaling Pathway

“…It is well established that H2O2 could be used to stimulate oxidative stress in vitro [30][31][32]. In the present study, we found that treatment with 400 μM H2O2 resulted in decreased cell viability in HTR8/SVneo cells, which is consistent with a previous study [1].…”

“…The transcription of HO-1 and NQO1, the downstream genes of Nrf2, are primarily under the control of Nrf2 in maintaining cell redox balance [49,50]. Under oxidative stress, Nrf2 could translocate into the nucleus to activate the expression of its downstream antioxidant enzymes [32]. Similar with the previous studies, the Nrf2 signaling was activated by H 2 O 2 treatment in order to compensate for the oxidative damage [32,51].…”

“…Bcl-2/Bax ratio has been reported to be an important determinant factor of apoptosis [40]. Ample pieces of evidence have also proven that H 2 O 2 treatment could increase cell apoptosis [32,41]. However, pre-treatment with curcumin inhibited cell apoptosis, which was demonstrated by declined apoptosis rate, reduced protein expression of cleaved-caspase 3 and increased expression level of Bcl-2/Bax ratio.…”

Protective Effects of Fucoidan against Hydrogen Peroxide-Induced Oxidative Damage in Porcine Intestinal Epithelial Cells

“…The increased nuclear NRF2 fluorescence intensity in IPEC-1 cells subjected to H 2 O 2 in the current study was therefore a cellular defense response. Recently, Zhuang et al [49] also reported that H 2 O 2 induces a translocation of NRF2 to the nuclei in rat small intestine epithelial cells. Contradictory with the increase in the nuclear NRF2 accumulation, the mRNA expression of NQO1 and SOD1 was downregulated in IPEC-1 cells during oxidative stress, and this may be due to cell antioxidant system failure.…”

Astragaloside IV Protects Against Oxidative Stress in Calf Small Intestine Epithelial Cells via NFE2L2-Antioxidant Response Element Signaling

“…Oxidative stress, arising from the excessive generation of reactive oxygen species (ROS) and imbalances in the antioxidant system, can damage multiple cellular components through DNA hydroxylation, protein denaturation, lipid peroxidation, and membrane rupture. This outcome leads to apoptosis and other modes of cell death [4,5]. Given the small intestine of calf gastrointestinal hypoplasia, oxidative stress can disrupt the integrity and functioning of calf intestinal epithelial cells, thereby affecting absorption and allowing pathogen invasion and disease [6].…”