Lactobacillus bulgaricus inhibits colitis-associated cancer via a negative regulation of intestinal inflammation in azoxymethane/dextran sodium sulfate model

BACKGROUND Colitis-associated cancer (CAC) accounts for 2%-3% of colorectal cancer (CRC) cases preceded by inflammatory bowel diseases (IBD) such as Crohn's disease and ulcerative colitis. Intestinal microbiota has been reported to play a central role in the pathogenesis of IBD and CAC. Recently, numerous prebiotics and probiotics have being investigated as antitumor agents due to their capacity to modulate inflammatory responses. Previous studies have indicated that lactic acid bacteria could be successfully used in managing sporadic CRC, however little is known about their role in CAC. AIM To investigate the effect of the probiotic Lactobacillus bulgaricus (L. bulgaricus) during the development of an experimental model of colitis associated colon cancer (CAC). METHODS C57BL/6 mice received an intraperitoneal injection of azoxymethane (10 mg/kg), followed by three cycles of sodium dextran sulphate diluted in water (5% w/v). Probiotic group received daily L. bulgaricus. Intestinal inflammation was determined by scoring clinical signs. Cytokines levels were determined from colon and/or tumor samples by ELISA BD OptEIATM kits. The level of significance was set at P < 0.05. Graphs were generated and statistical analysis performed using the software GraphPad Prism 6.0. RESULTS L. bulgaricus treatment inhibited of total tumor volume and mean size of tumors. In addition, the probiotic also attenuated the clinical signs of intestinal inflammation inducing a decrease in intestinal and tumor levels of IL-6, TNF-alpha, IL-17, IL-23 and IL-1 beta. CONCLUSION Our results suggest a potential chemopreventive effect of probiotic on CAC. L. bulgaricus regulates the inflammatory response and preventing CAC.