Advanced oxidation protein products induce intestine epithelial cell death through a redox-dependent, c-jun N-terminal kinase and poly (ADP-ribose) polymerase-1-mediated pathway

OPEN Citation: Cell Death and Disease (2014) 5, e1006; doi:10.1038/cddis.2013.542 & 2014 Macmillan Publishers Limited All rights reserved 2041-4889/14 www.nature.com/cddis Advanced oxidation protein products induce intestine epithelial cell death through a redox-dependent, c-jun N-terminal kinase and poly (ADP-ribose) polymerase-1-mediated pathway F Xie1, S Sun2, A Xu3, S Zheng4, M Xue1, P Wu1, JH Zeng4 and L Bai*,1,5 Advanced oxidation protein products (AOPPs), a novel protein marker of oxidative damage, have been confirmed to accumulate in patients with inflammatory bowel disease (IBD), as well as those with diabetes and chronic kidney disease. However, the role of AOPPs in the intestinal epithelium remains unclear. This study was designed to investigate whether AOPPs have an effect on intestinal epithelial cell (IEC) death and intestinal injury. Immortalized rat intestinal epithelial (IEC-6) cells and normal Sprague Dawley rats were treated with AOPP-albumin prepared by incubation of rat serum albumin (RSA) with hypochlorous acid. Epithelial cell death, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit activity, reactive oxygen species (ROS) generation, apoptosis-related protein expression, and c-jun N-terminal kinase (JNK) phosphorylation were detected both in vivo and in vitro. In addition, we measured AOPPs deposition and IEC death in 23 subjects with Crohn’s disease (CD). Extracellular AOPP-RSA accumulation induced apoptosis in IEC-6 cultures. The triggering effect of AOPPs was mainly mediated by a redox-dependent pathway, including NADPH oxidase-derived ROS generation, JNK phosphorylation, and poly (ADP-ribose) polymerase-1 (PARP-1) activation. Chronic AOPP-RSA administration to normal rats resulted in AOPPs deposition in the villous epithelial cells and in inflammatory cells in the lamina propria. These changes were companied with IEC death, inflammatory cellular infiltration, and intestinal injury. Both cell death and intestinal injury were ameliorated by chronic treatment with apocynin. Furthermore, AOPPs deposition was also observed in IECs and inflammatory cells in the lamina propria of patients with CD. The high immunoreactive score of AOPPs showed increased apoptosis. Our results demonstrate that AOPPs trigger IEC death and intestinal tissue injury via a redox-mediated pathway. These data suggest that AOPPs may represent a novel pathogenic factor that contributes to IBD progression. Targeting AOPP-induced cellular mechanisms might emerge as a promising therapeutic option for patients with IBD. Cell Death and Disease (2014) 5, e1006; doi:10.1038/cddis.2013.542; published online 16 January 2014 Subject Category: Experimental Medicine The term inflammatory bowel disease (IBD) encompasses two major forms: ulcerative colitis and Crohn’s disease (CD), both of which are characterized by chronic or recurrent relapsing gastrointestinal inflammation.1 Although a number of risk factors have been identified, IBD etiology and pathogenesis remain unclear. A peroxidation/antioxidation imbalance has been demonstrated in IBD development,2,3 and this results in excessive reactive oxygen species (ROS) generation and oxidative stress. Such changes are able to induce the oxidative modification of proteins, thus causing structural and functional changes.4 The recently discovered advanced oxidation protein products (AOPPs) are dityrosinecontaining and cross-linking protein products formed during 1 oxidative stress that are formed mainly by the reaction of plasma proteins with chlorinated compounds.5,6 Increased plasma AOPP formation has been reported in patients with chronic kidney disease,5 diabetes,7 and chronic hepatitis C.8 As a novel protein marker of oxidant-mediated protein damage, AOPPs participate in these pathophysiologic conditions. They are capable of inducing vascular endothelial dysfunction via a receptor for advanced glycation endproducts (RAGE)-mediated signaling pathway.9 AOPPs have also been reported to induce overproduction of extracellular matrix and the fibrogenic factor transforming growth factor-b1. Furthermore, Zhou et al. reported that AOPP accumulation promotes podocyte apoptosis and depletion through RAGE.10 Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Department of Hepatobiliary Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China; 3Huizhou Medical Institute, Huizhou, China; 4Department of Orthopedic and Spinal Surgery, Southern Medical University, Guangzhou, China and 5Department of Huiqiao Building, Southern Medical University, Guangzhou, China *Corresponding author: L Bai, Department of Huiqiao Building, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. Tel: +86 20 61642251; Fax: +86 20 61642494; E-mail: Keywords: AOPPs; intestine epithelial cell; death; redox; c-jun N-terminal kinase; PARP-1 Abbreviations: AIF, apoptosis-inducing factor; AOPPs, advanced oxidation protein products; CD, Crohn’s disease; DPI, diphenylene iodinium; IBD, inflammatory bowel disease; IEC, intestinal epithelial cell; JNK, c-jun N-terminal kinase; PAR, polymers of ADP-ribose; PARP-1, poly(ADP-ribose) polymerase-1; PBS, phosphatebuffered saline; RAGE, receptor for advanced glycation end products; RSA, rat serum albumin; ROS, reactive oxygen species; TUNEL, terminal deoxynucleotidyl transferase dUTP nick-end labeling; UC, ulcerative colitis 2 Received 20.9.13; revised 04.12.13; accepted 05.12.13; Edited by A Stephanou AOPPs induce intestinal cell death via redox and PARP-1 F Xie et al 2 Our recent study demonstrated that AOPPs inhibit the proliferation and differentiation of rat osteoblast-like cells via ROS generation and nuclear factor-kB signaling.11 Intestinal epithelial cells (IECs) are organized as a single cell layer that forms a contiguous lining and functional barrier that maintains gut structural integrity to separate the bowel wall from microbes and toxins.12,13 IEC proliferation and death must be tightly regulated to maintain the structural integrity of the intestinal mucosal epithelium, and changing this balance can have pathological consequences. There is a growing body of literature showing that excessive cell death is associated with chronic inflammation, as seen in patients with IBD, and this could contribute to IBD pathophysiology.14,15 Two major cell death pathways, the caspase-3 pathway and the recently identified caspase-independent pathway mediated by the activation of poly (ADP-ribose) polymerase-1 (PARP-1), lead to apoptotic cell death following ischemia, inflammatory injury, and ROS-induced injury.15,16 Although previous studies have revealed that oxidative stress results in plasma accumulation of AOPPs in IBD,17,18 the effects of AOPPs on IECs remain unclear. It is unknown whether AOPPs affect IEC proliferation and death or intestinal tissue injury. Moreover, there is (...truncated)