Lactobacillus spp. inhibits the growth of HCT-116 and reduces IL-8 secretion by Salmonella typhimurium-infected HCT-116 colorectal carcinoma cells

Abstract

Salmonella typhimurium causes symptoms resembling typhoid fever and gastroenteritis in humans. Its toxicity is due to an outer membrane consisting largely of lipopolysaccharides (LPS) which is responsible for the host immune response. The aim of this study is to evaluate the antimicrobial, anti-apoptotic ability of Lactobacillus plantarum and reduce Salmonella-induced pro-inflammatory cytokine IL-8 secretion. Adhesive tests were performed using lactobacilli co-cultured with the colon cancer cell line HCT-116 for 2 hours. The strains displaying the highest adhesion were selected for downstream 3- (4, 5- Dimethylthiazol -2-yl) -2, 5- diphenyltetrazolium bromide (MTT) tests to assess cytotoxicity. The supernatants of Lactobacillus cultured with HCT-116 cells for 24 and 48 h to evaluate the inhibitory effect. To determine Interleukin 8 (IL-8) secretion in colon cancer induced by S. typhimurium, we stimulated HCT-116 cells with S. typhimurium and co-cultured with lactobacilli for 24 h. Lactobacilli had the most significant inhibitory effects on cell growth, and their inhibitory effects were time-dependent. Strain No. 03-03-026 caused cancer cell deoxyribonucleic acid (DNA) fragmentation, and the anti-apoptosis protein (B-cell lymphoma 2) was reduced in the HCT-116 cells as determined. IL-8 production in colon cancer cells was significantly reduced by these lactobacilli. Our results suggested that lactobacilli maybe effectively reduce the numbers of S. typhimurium, IL-8 levels and the anti-apoptotic phosphorylated-p38 mitogen-activated protein kinase and B-cell lymphoma 2 proteins. Lactobacillus can be added to the diet as a food additive to prevent colorectal cancer and used to be the prophylactic agent against S. typhimurium.