Abstract
Intestinal epithelial cells can respond to certain bacteria by producing an array of cytokines and chemokines which are associated with host immune responses. Lactobacillus acidophilus NCFM is a characterized probiotic, originally isolated from human feces. This study aimed to test the ability of L. acidophilus NCFM to stimulate cytokine and chemokine production in intestinal epithelial cells and to elucidate the mechanisms involved in their upregulation. In experiments using intestinal epithelial cell lines and mouse models, we observed that L. acidophilus NCFM could rapidly but transiently upregulate a number of effector genes encoding cytokines and chemokines such as interleukin 1α (IL-1α), IL-1β, CCL2, and CCL20 and that cytokines showed lower expression levels with L. acidophilus NCFM treatment than chemokines. Moreover, L. acidophilus NCFM could activate a pathogen-associated molecular pattern receptor, Toll-like receptor 2 (TLR2), in intestinal epithelial cell lines. The phosphorylation of NF-κB p65 and p38 mitogen-activated protein kinase (MAPK) in intestinal epithelial cell lines was also enhanced by L. acidophilus NCFM. Furthermore, inhibitors of NF-κB (pyrrolidine dithiocarbamate [PDTC]) and p38 MAPK (SB203580) significantly reduced cytokine and chemokine production in the intestinal epithelial cell lines stimulated by L. acidophilus NCFM, suggesting that both NF-κB and p38 MAPK signaling pathways were important for the production of cytokines and chemokines induced by L. acidophilus NCFM.