Probiotic Escherichia coli Nissle 1917 activates DC and prevents house dust mite allergy through a TLR4-dependent pathway.

Experimental animal and human studies have demonstrated that probiotic strains have beneficial effects on allergy. Here we report that the probiotic Escherichia coli Nissle 1917 strain (EcN) is able to activate DC, as shown by important cytokine synthesis together with up-regulation of membrane expression of CD40, CD80 and CD86. This EcN-induced DC activation was strictly dependent on the TLR4 signaling pathway and was also associated with stimulation of NF-kappaB and MAPK.