Lactobacillus reuteri NK33 and Bifidobacterium adolescentis NK98 Alleviate Escherichia coli-Induced Depression and Gut Dysbiosis in Mice

Lactobacillus reuteri NK33 (NK33) and Bifidobacterium adolescentis NK98 (NK98) alleviate immobilization stress-induced depression. To understand the gut microbiota-mediated mechanisms of NK33 and NK98 against depression, we examined their effects on Escherichia coli K1 (K1)-induced depression and gut dysbiosis in mice. NK33, NK98, and their mixtures (1:1, 4:1, and 9:1) mitigated K1-induced depression and colitis. NK33 and NK98 additively or synergistically increased BDNF(+)/NeuN(+) cell population and suppressed NF-κB action in the hippocampus. They alleviated gut dysbiosis by reducing the Proteobacteria population and increasing the Clostridia population. These results suggest that NK33 and NK98 may alleviate depression and colitis by ameliorating gut dysbiosis.