Contents lists available at ScienceDirect European Journal of Pharmacology journal homepage: www.elsevier.com/locate/ejphar Full length article Ameliorating effect of TI-1-162, a hydroxyindenone derivative, against TNBS-induced rat colitis is mediated through suppression of RIP/ASK-1/ MAPK signaling Pallavi Gurung 1 , Suhrid Banskota 1 , Nikita Katila, Jaya Gautam, Tara Man Kadayat, Dong-Young Choi, Eung Seok Lee, Tae Cheon Jeong, Jung-Ae Kim ⁎ College of Pharmacy, Yeungnam University, Gyeongsan 38541, South Korea ARTICLE INFO Keywords: Inflammatory bowel disease (IBD) TNF-α RIP-1 ASK-1 Epithelial apoptosis Hydroxyindenone derivative TI-1-162 ABSTRACT The pathogenesis of inflammatory bowel disease (IBD) is associated with production of immense pro-in- flammatory cytokines including TNF-α. Once generated, TNF-α stimulates production of various pro-in- flammatory cytokines and disrupts mucosal barrier by inducing inflamed mucosal epithelial cell death. In the present study, we investigated inhibitory effects of TI-1-162, a hydroxyindenone derivative, against TNF-α- induced and TNBS-induced colon inflammation. TI-1-162 showed inhibitory effect on the TNF-α-induced ad- hesion of U937 monocytic cells to HT-29 colonic epithelial cells (IC 50 = 0.83 ± 0.12 μM), which is an in vitro model representing the initial step of colitis. In addition, TI-1-162 suppressed TNF-α-stimulated caspase-3 ac- tivation and HT-29 cell apoptosis. These in vitro inhibitory activities of TI-1-162 correlated to recovery changes in in vivo colon tissues, such as downregulation of adhesion molecules (ICAM-1, VCAM-1) and chemokines (CCL11, CXCL1, CXCL2, CXCL3, CX3CL1) revealed by gene expression array and Western blot analyses. Such molecular recovery of colon epithelium from TNBS-treated rats corresponded to the recovery in body weight, colon weight/length, and myeloperoxidase level by TI-1-162 (10 and 30 mg/kg/day, orally). In relation to action mechanism, TI-1-162 did not disturb TNF-α binding to its receptor, but suppressed phosphorylation of RIP-1, ASK-1, JNK and p38, and nuclear translocation of NF-kB and AP-1, which corresponded to down regulation of inflammatory cytokines in TNF-α-treated cells (HT-29 and U937) and TNBS-treated rat colon tissues. Taken together, the results indicate that the protective effects of TI-1-162 against colon inflammation and epithelial cell death are associated with its inhibitory action in RIP/ASK-1/MAPK signaling pathway downstream to TNF re- ceptor 1. 1. Introduction Inflammatory Bowel Disease (IBD), encompassing Crohn's Disease (CD) and Ulcerative colitis (UC), describes chronic and progressive in- flammation of the digestive tract (Yapali, 2007). Both CD and UC usually involve severe diarrhea, abdominal pain, fatigue and weight loss, which may lead to debilitating complications. The etiology of IBD has not been completely revealed, however, aberrant and prolonged immune response triggered by genetic and environmental factors are considered as the major etiology of the disease (Danese et al., 2004; Rocchi et al., 2012). IBD is often characterized by an infiltration of mucosal immune cells (macrophages, neutrophils and lymphocytes) into the intestinal tissue producing a wide range of pro-inflammatory cytokines, resulting in imbalance between pro- and anti-inflammatory cytokines (Neurath, 2014a; Rogler and Andus, 1998). The increased levels of pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6, and IFN-γ are mostly responsible for the pathogenesis of IBD (Schreiber et al., 1995; Zhang and Li, 2014). In the inflamed mucosa of patients with IBD, TNF-α exerts various functions such as stimulating production of other pro-inflammatory cytokines and chemokines, disrupting barrier function, and promoting cell death of intestinal epithelial cells (Neurath, 2014a; Parameswaran and Patial, 2010). Binding of TNF-α to its receptor (TNFR) induces receptor trimerization and recruits downstream adaptor molecules, such as TNF receptor type 1-associated death domain protein (TRADD), TNF receptor-associated factor 2 (TRAF2), and receptor interacting protein-1 (RIP-1). In turn, RIP-1 recruits mitogen-activated protein ki- nase kinase and p38 to activate inhibitor of κB kinase (IKK) complex https://doi.org/10.1016/j.ejphar.2018.03.027 Received 24 December 2017; Received in revised form 14 March 2018; Accepted 15 March 2018 ⁎ Corresponding author. 1 These authors contributed equally to this work. E-mail address: jakim@yu.ac.kr (J.-A. Kim). European Journal of Pharmacology 827 (2018) 94–102 Available online 16 March 2018 0014-2999/ © 2018 Published by Elsevier B.V. T