Novel features of the rat model of inflammatory bowel disease based on 2,4,6-trinitrobenzenesulfonic acid- induced acute colitis

The 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced acute inflammatory bowel disease (IBD) model in the rat is discussed, focusing on the details of the TNBS instillation and highlighting the advantages and limitations of this model. For determination of the timedependent action of 50% ethanol and different doses of TNBS, male Wistar rats were treated with 50% ethanol or 10 mg or 30 mg of TNBS dissolved in 50% ethanol. The TNBS-induced inflammation peaked 48-72 h after installation and the colitis caused by 30 mg of TNBS was more severe than that caused by 10 mg of TNBS. To test the effectiveness of sulfasalazine (SASP), male rats were treated with 10 mg of TNBS or with 10 mg of TNBS and SASP, and 72 h later the extent of mucosal damage was determined. Orally administered 50 mg/kg/day SASP proved to reduce the TNBS-induced colonic inflammation in rats significantly. The TNBS-induced colitis model facilitates a better understanding of the immunopathological mechanisms of IBD. Optimization of the dose of TNBS and oral SASP as positive control in TNBS-induced colitis in rats furnishes an appropriate test system for new anti-IBD drugs. Acta Biol Szeged 58(2):127-132 (2014) Key WordS colitis rat IBD model TNBS Accepted Dec 2, 2014 *Corresponding author. E-mail: [email protected] 127 Inflammatory bowel disease (IBD) is a chronic disease of the gastrointestinal tract, primarily manifested as Crohn’s disease (CD) and ulcerative colitis (UC). Environmental, genetic and immunological factors all contribute significantly to the pathophysiology of IBD, but the precise mechanisms remain unclear (Kaser et al. 2010). Epidemiological studies have revealed an increasing incidence of IBD in northwestern Europe, the USA and eastern Canada, suggesting that environmental and lifestyle factors play a major role in the development and progression of this disease (Vatn 2008; Kappelman et al. 2013; Ng et al. 2013). Several animal models have been developed in attempts to understand the pathogenesis of IBD and to test pharmacological molecules and therapeutic targets. However, CD and UC are chronic diseases, while animal models are necessarily primarily acute, in order to limit the discomfort and the pain caused to the animals and to reduce the costs associated with the use of reagents and supplies. Invertebrate models of IBD, involving Caenorhabditis elegans (Chinnadurai et al. 2008; Kang et al. 2010) and Drosophila melanogaster (Liu et al. 2010; Apidianakis et al. 2011), have been used to investigate the genetic factors and signalling pathways involved in the pathogenesis of these diseases and to identify novel therapeutic agents (Lin et al. 2011). However, the various vertebrate models (most commonly mice and rats) more closely resemble the complexity of the human physiology than those with invertebrate animals, and may reflect the different subtypes of patients with IBD, and they are important in preclinical studies (Jurjus et al. 2004). Rodent models of chemically induced IBD are widely used because of their simplicity and the possibility of the control of the degree of inflammation (Table 1). However, the differences in protocols lead to difficulties in reproducing reported experiments and in comparing measured parameters between studies. The inconsistent variables generally include the rodent strains used, the amounts and concentrations of chemical agents and the time of sacrifice in relation to the treatment. The 2,4,6-trinitrobenzenesulfonic acid (TNBS) model was originally described by Morris et al. (Morris et al. 1989). TNBS (0.5 to 4.0 mg for mice and 10 to 30 mg for rats) is dissolved in 45% or 50% ethanol, which can lead to the destruction of the mucosal barrier. As a hapten, TNBS can bind to the endogenous proteins, giving rise to haptenprotein formation, which induces the interleukin-12 (IL-12) and T helper 1-mediated local immunological response. The activated macrophages produce inflammatory mediators,