Probiotic–intestinal epithelium crosstalk: mechanisms of adhesion, signalling, and immunomodulation

A large number of studies have highlighted the important role of probiotics in maintaining intestinal homeostasis and promoting host health. Although, several mechanisms have been proposed in recent years the exact mechanisms by which probiotic exert their effect on the immune system are not completely understood. However, intestinal epithelial cells (IEC) have an undisputed participation in the initial stages of communication between probiotics and host cells. This review summarises the current knowledge on the interaction of probiotics with IEC and the consequent stimulation of gut immune cells. In addition, it emphasises the importance of probiotics adhesion to the intestinal mucus or to the IEC as a crucial step to sustain the gut immune surveillance, ensure the probiotic efficacy and promote the activation of immune cells in organs beyond the gut.