Autophagy Deficiency Diminishes Indomethacin-Induced Intestinal Epithelial Cell Damage through Activation of the ERK/Nrf2/HO-1 Pathway

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause epithelial cell damage in the stomach, intestine, and colon. NSAIDs are reported to induce autophagy and apoptosis in intestinal epithelial cells; however, their role in cell damage is poorly understood. To examine the role of autophagy in cell damage, we used autophagy-related gene Atg5-conditional knockout mice, in which the Atg5 gene is only knocked out in intestinal epithelial cells. In an indomethacin (IM)-induced gastrointestinal ulcer mouse model, intestinal epithelium damage was reduced in Atg5-conditional knockout mice compared with wild-type mice. IM-induced damage in IEC6 rat intestinal epithelial cells was reduced when Atg5 was silenced (IEC6shAtg5 cells). Western blot analyses indicated that IM-induced apoptosis decreased, and the potent, oxidative stress-related extracellular signal-regulated kinase (ERK)/nuclear factor-erythroid2-like2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was upregulated in IEC6shAtg5 cells. An experiment using a reactive oxygen species (ROS)-sensitive fluorescent dye in IEC6shAtg5 cells revealed that the amount of ROS at the baseline and the rate of increase after IM treatment were lower than in intact IEC6 cells. The mitochondrial membrane potential at the baseline and the reduction rate in IM-treated IEC6shAtg5 cells were lower than in intact IEC6 cells, indicating that autophagy deficiency increased ROS production caused by mitochondrial disturbance. Furthermore, MnTMPyP, a manganese-superoxide dismutase mimetic, significantly inhibited IM-induced autophagy and subsequent apoptosis as well as activation of the ERK/Nrf2/HO-1 pathway. These data suggest that autophagy deficiency and subsequent activation of the ERK/Nrf2/HO-1 pathway diminished IM-induced, apoptosis-mediated intestinal epithelial cell damage, and genetic analyses of single nucleotide polymorphisms in autophagyrelated genes could predict NSAID-induced intestinal injury.

Natural polyphenols prevent indomethacin-induced and diclofenac-induced Caco-2 cell death by reducing endoplasmic reticulum stress regardless of their direct reactive oxygen species scavenging capacity

“…In this study, both INDO and DIC were able to induce cytotoxicity in human intestinal Caco‐2 cells possibly via production of ROS, ER stress and mitochondria dysfunction. Several studies suggested that ROS was an underlying cause of intestinal cell damage after exposure to either INDO or DIC . Both INDO and DIC were able to increase intracellular ROS in intestinal Caco‐2 cells possibly through inhibiting mitochondrial complex I activity .…”

Tetrahydroxystilbene Glucoside Exerts Cytoprotective Effect against Hydrogen Peroxide-induced Cell Death Involving ROS Production and Antioxidant Enzyme Activation

“…In GES-1cells, HO-1 was increased about 2.16 folds compared with that of control group and NQO1 was increased about 1.66 folds. In SGC-7901 cells, HO-1 was increased [4,20] .…”

Anti-Ulcer Efficacy of Soluble Epoxide Hydrolase Inhibitor TPPU on Diclofenac-Induced Intestinal Ulcers

“…ER stress and apoptosis are involved in NSAID-induced ulcers in stomach and intestine (Tsutsumi et al, 2004;LoGuidice et al, 2010;Ohyama et al, 2012;Harada et al, 2015). TPPU might have decreased the number of ulcers by suppressing ER stress, because sEH inhibition and sEH gene deletion are reported to decrease ER stress in different disease models (Bettaieb et al, 2013;Harris et al, 2015).…”

“…TPPU might have decreased the number of ulcers by suppressing ER stress, because sEH inhibition and sEH gene deletion are reported to decrease ER stress in different disease models (Bettaieb et al, 2013;Harris et al, 2015). NSAIDinduced intestinal ulcers are characterized by apoptosis of intestinal epithelial cells (Harada et al, 2015). EETs, sEH inhibition, and sEH gene deletion decrease apoptosis of cells (Luo et al, 2010;Liu et al, 2013).…”