Bifidobacterium, Lactobacillus, and Roseburia spp metabolize polyunsaturated fatty acids, including omega-3 and omega-6 fatty acids, to conjugated linoleic acid (CLA) (53, 54), thereby inhibiting COX-2/5-LOX and TLR4/NF-κB signaling pathway and attenuating skin lesions of AD (55). This evidence concerns the gene TLR4 and Alzheimer disease.