MAPT and Alzheimer disease: Additionally, the gut microbiome’s altered state in AD could influence the disease course through its impact on the metabolism of amyloid precursors and tau phosphorylation, thereby affecting the aggregation of amyloid plaques and the formation of neurofibrillary tangles, hallmark features of Alzheimer’s pathology.74 Under this hypothesis, the microbial dysbiosis can induce an increase in generalized reactive oxygen species generation, that activate NF-kB and proinflammatory mRNA-34a, eventually downregulating TREM-2 receptors on microglial cells.