NFKB1 and major depressive disorder: Lactobacillus reukii NK33, Bifidobacterium adolescentis NK98, and Lactobacillus gasseri NK109 can reverse the intestinal flora imbalance induced by Escherichia coli K1, inhibit NF‐κB activation in the hippocampus of mice, effectively prevent the occurrence of inflammatory responses in the brain, and reduce K1‐induced cognitive impairment and depression‐like behaviors [131, 132].