Histoimmunological Evaluation for the Efficacy of Entero Nutrient Containing n-3 Fatty Acids in TNBS Rat Colitis Model

Abstract

Inflammatory bowel disease (IBD) is a chronic disease of the digestive tract, with complicated and multifactoral etiology. An exaggerated intestinal immune response to otherwise innocuous stimuli plays a key role in the pathophysiology of this intestinal disorder. Nutritional intervention is an important therapy for patients with IBD. But the ratio of n-3 and n-6 fatty acids on the modulation of intestinal inflammation is not clear. Interleukin-16 (IL-16) is a pleiotrophic cytokine secreted mainly by CD8+ T cells. The properties of IL-16 suggest that it may be involved in pathophysiological process of chronic inflammatory diseases. The aim was to determine the effect of an n-3 fatty acid-rich diet (RACOL®) on the expressions of cytokines and mucosal integrity in trinitrobenzene surufonic acid (TNBS) induced rat colitis. 7 week-male Wistar rats were divided into 4 groups. 1. Normal laboratory diet (n = 10), 2. RACOL® diet only (n = 10), 3. TNBS induced colitis with normal laboratory diet (n = 10), 4. TNBS induced colitis with RACOL® diet (n = 10). TNBS induced colitis rats were given an intracolonic injection of 50 mg of TNBS dissolved in 50% ethanol. From day 2, rats were fed 80 kcal/day of RACOL® and/or normal laboratory diet, and sacrified on the 14th and the 28th days. One hour before sacrifice, 0.2 mg/g/rat of BrdU was injected. The expressions of BrdU labeled cells, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-16 were studied by the ABC staining method and DAB staining lesions in colonic mucosa were estimated by an image analyzer system. Apoptosis was assessed by the TUNEL method. Macroscopic and histological findings were classified by the Morris and Vilaseca method. TNBS application increased colonic epithelial cell proliferation, but nutrition by RACOL® reduced this stimulation. Number of apoptosis cells was also increased by TNBS application, but nutrition of RACOL® reduced the number of apoptosis cells, which had been increased by TNBS treatment. The expressions of cytokines had been increased in TNBS-colitis rats, but were reduced by the RACOL®. In conclusion, the effect of nutrition by n-3 fatty acid-rich diet, RACOL®, is an important treatment through the inhibition of inflammatory mediators, and colonic hyper-proliferation.