The Bacteria Key: A Novel Theoretical Dual-Target Mechanism Linking Gut-Derived Butyrate to Blood-Brain Barrier Integrity and Non-Amyloidogenic APP Processing in Alzheimer's Disease Prevention

Alzheimer’s Disease (AD) pathogenesis is fundamentally driven by a multi-faceted cascade involving homeostatic breakdowns within both the central nervous system (CNS) and its surrounding vascular boundaries. This academic proposal delineates a novel theoretical framework designated as “The Bacteria Key”. We hypothesize that targeted therapeutic modulation of the intestinal microbiota to optimize endogenous Short-Chain Fatty Acid (SCFA) production—specifically butyrate—can concurrently address these distinct pathological vectors. Mechanistically, this model positions butyrate as a dual-action epigenetic and cellular signaling mediator that upregulates vital endothelial tight junction proteins (Claudin-5 and Occludin) to reinforce BBB structural integrity, while simultaneously functioning as a histone deacetylase (HDAC) inhibitor to upregulate ADAM10 (α-secretase) expression. By shifting metabolic kinetics toward the non-amyloidogenic pathway, this endogenous biochemical axis offers a non-pharmacological, preventative paradigm that circumvents the classic constraints of drug delivery across the BBB.