Preventative effects of a probiotic,Lactobacillus salivarius ssp.salivarius,in the TNBS model of rat colitis

R5; AIM: To investigate the intestinal anti-inflammatory effect and mechanism of a probiotic Lactobacillus sakuvarius ssp.salivariusCECT5713 in the TNBS model of rat colitis.METHODS: Female Wistar rats (180-200 g) were used in this study. A group of rats were administered orally the probiotic L. salivarius ssp. salivarius (5×108 CFU suspended in 0.5 mL of skimmed milk) daily for 3 wk. Two additional groups were used for reference, a non-colitic and a control colitic without probiotic treatment, which received orally the vehicle used to administer the probiotic. Two weeks after starting the experiment, the rats were rendered colitic by intracolonic administration of 10 mg of TNBS dissolved in 0.25 mL of 500 mL/L ethanol. One week after colitis induction, all animals were killed and colonic damage was evaluated both histologically and biochemically. The biochemical studies performed in colonic homogenates include determination of myeloperoxidase (MPO) activity,glutathione (GSH) content, leukotriene B4 (LTB4) and tumor necrosis factor α (TNF-α) levels, as well as inducible nitric oxide synthase (iNOS) expression. In addition, the luminal contents obtained from colonic samples were used for microbiological studies, in order to determine Lactobacilli and Bifidobacteria counts.RESULTS: Treatment of colitic rats with L. salivarius ssp.salivarius resulted in amelioration of the inflammatory response in colitic rats, when compared with the corresponding control group without probiotic treatment. This antiinflammatory effect was evidenced macroscopically by a significant reduction in the extent of colonic necrosis and/or inflammation induced by the administration of TNBS/ethanol (2.3+0.4 cm vs3.4+0.3 cm in control group,P＜0.01) and histologically by improvement of the colonic architecture associated with a reduction in the neutrophil infiltrate in comparison with non-treated colitic rats. The latter was confirmed biochemically by a significant reduction of colonic MPO activity (105.3+26.0 U/g vs180.6±21.9 U/g, P＜0.05), a marker of neutrophil infiltration. The beneficial effect was associated with an increase of the colonic GSH content (1 252±42 nmol/g vs 1 087+51 nmol/g, P＜0.05),which is depleted in colitic rats, as a consequence of the oxidative stress induced by the inflammatory process. In addition, the treatment of colitic rats with L. salivarius resulted in a significant reduction of colonic TNF-α levels (509.4±68.2 pg/g vs782.9±60.1 pglg, P＜0.01) and in a lowe