{"id":1556,"date":"2025-10-12T21:06:49","date_gmt":"2025-10-13T01:06:49","guid":{"rendered":"https:\/\/www.madischu.com\/?p=1556"},"modified":"2025-10-12T21:06:49","modified_gmt":"2025-10-13T01:06:49","slug":"promising-therapy-in-alzheimers-disease","status":"publish","type":"post","link":"https:\/\/www.life360coach.com\/index.php\/2025\/10\/12\/promising-therapy-in-alzheimers-disease\/","title":{"rendered":"Promising Therapy in Alzheimer’s Disease"},"content":{"rendered":"
Short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, emerge as promising therapeutic agents in Alzheimer’s disease (AD).
\nShort-chain fatty acids are produced by gut microbiota fermentation of dietary fibers.
\nThese SCFAs play a complex role in Alzheimer’s disease (AD) through the microbiota-gut-brain axis.
\nAD patients exhibit gut dysbiosis with reduced SCFA-producing bacteria (e.g., <\/span>Faecalibacterium prausnitzii<\/span><\/span>, <\/span>Roseburia<\/span><\/span> spp.), leading to altered circulating SCFA levels\u2014typically elevated acetate and valerate but decreased butyrate\u2014which correlate with amyloid-\u03b2 (A\u03b2) deposition, tau pathology, neuroinflammation, and cognitive decline.
\nSCFAs modulate AD progression by influencing microglial activation, blood-brain barrier(BBB) integrity, and synaptic plasticity, though effects can be beneficial (e.g., anti-inflammatory) or detrimental (e.g., impaired A\u03b2 phagocytosis) depending on concentration, disease stage, and context.<\/span><\/span><\/span><\/span>Recent 2024\u20132025 studies emphasize the SCFAs-microglia pathway as a therapeutic target, with preclinical evidence supporting microbiome modulation to restore SCFA homeostasis and slow neurodegeneration.<\/p>\n


\nKey Mechanisms<\/strong>
\n<\/span><\/span><\/span>SCFAs exert dual effects in AD via epigenetic, signaling, and metabolic pathways, primarily targeting microglia\u2014the brain’s resident immune cells that drive neuroinflammation and A\u03b2\/tau pathology.<\/span><\/span><\/span><\/p>\n

    \n
  • Epigenetic Regulation<\/span><\/span><\/strong>:
    \nButyrate and propionate inhibit histone deacetylases (HDACs), promoting hyperacetylation (e.g., H3K9, H3K18) that suppresses NF-\u03baB translocation and pro-inflammatory genes (IL-1\u03b2, TNF-\u03b1, COX-2), shifting microglia from M1 (pro-inflammatory) to M2 (anti-inflammatory) phenotypes.
    \nIn APP\/PS1 mice, oral acetate administration for 4 weeks upregulated GPR41 in A\u03b2-stimulated BV-2 microglia, inhibiting HDAC-related pathways and reducing inflammatory markers.
    \nSodium butyrate induced hyperacetylation at H3K9 and H3K18 sites in LPS-stimulated BV-2 microglia. In AD mouse models, sodium butyrate ameliorates synaptic plasticity impairment by inhibiting neuroinflammation via HDAC inhibition.<\/span><\/span><\/li>\n
  • Receptor-Mediated Signaling<\/span><\/span><\/strong>: SCFAs bind G-protein-coupled receptors (FFAR2\/3, GPR109A) on microglia, inhibiting TLR4\/NF-\u03baB and ERK\/JNK pathways, reducing ROS\/NO production, and enhancing phagocytosis or autophagy for A\u03b2 clearance. Over 60% of hippocampal FFAR3 expression co-localizes with activated microglia. In APP\/PS1 mice, acetate upregulated GPR41 in BV-2 microglia, inhibiting phosphorylation of NF-\u03baB p65, ERK, and JNK, and reducing COX-2 and IL-1\u03b2 levels. Butyrate reduced A\u03b2-induced CD11b and COX-2 in BV-2 microglia and inhibited NF-\u03baB p65 phosphorylation. Knockout of GPR41\/43 accelerated cognitive decline and impaired hippocampal neurogenesis in 5\u00d7FAD mice, but SCFAs intake reversed this by upregulating defensive genes (e.g., B2m, Fgl2, H2-K1) and antigen presentation pathways.<\/span><\/span><\/li>\n
  • Metabolic Reprogramming<\/span><\/span><\/strong>: SCFAs restore tricarboxylic acid (TCA) cycle flux and mitochondrial function in microglia, balancing energy and curbing inflammasome (NLRP3) activation, which exacerbates synaptic loss in AD.
    \nGut-derived 13C-acetate can reach the brain and be metabolized by microglia into TCA cycle intermediates (e.g., citrate, \u03b1-ketoglutarate, fumarate, malate, succinate), thereby restoring the mitochondrial dysfunction observed in germ-free mice. In 5\u00d7FAD mice, acetate inhibited phagocytosis by inducing cytokine expression, exacerbating A\u03b2 burden, and increased mitochondrial activity, ROS production, oxidative phosphorylation, and membrane potential in A\u03b2-phagocytosing microglia. Acetate improved TCA cycle flux by stimulating short-chain CoA metabolism and increasing acetyl-CoA levels, reducing microglial reactivity. Butyrate reversed FXN depletion-induced mitochondrial oxidative capacity loss via GPR109A, stimulating the itaconate-Nrf2-GSH pathway and reducing ROS.<\/span><\/span><\/li>\n
  • Indirect Effects via Gut-Brain Axis<\/span><\/span><\/strong>: Circulating SCFAs influence peripheral immunity (e.g., Treg\/Th17 balance) and vagal signaling, reducing gut permeability and systemic translocation of inflammatory signals to the brain. Propionate pre-treatment reduced peripheral Th17 infiltration and IL-17A levels, decreasing microglial activation in perioperative cognitive dysfunction models relevant to AD. FFAR2 knockout in myeloid cells downregulated microglial inflammatory genes.
    \nSCFAs promoted Treg generation in the spleen, affecting microglial cytokine release. In 5\u00d7FAD mice, peripheral immune pathways mediated SCFAs’ effects on microglial transcriptome and neurogenesis. Elevated acetate may worsen A\u03b2 burden by impairing microglial metabolism, while butyrate supports barrier integrity and BDNF expression.
    \nSCFAs suppress pro-inflammatory cytokines (IL-1\u03b2, MCP-1, TNF-\u03b1) and reduce THP-1 phagocytosis; acetate reverses LPS-induced phospholipase C \u03b21\/COX-1\/COX-2 and reduces TNF-\u03b1\/IL-6 in astrocytes via p38 MAPK\/NF-\u03baB downregulation, increasing IL-4 via TGF-\u03b21\/H3K9 acetylation;
    \nButyrate inhibits COX-2 in A\u03b2-microglia via NF-\u03baB.<\/span><\/span><\/li>\n<\/ul>\n

    Evidence from Preclinical and Clinical Studies
    \n<\/strong>
    \n<\/span><\/span><\/span>Studies reveal context-dependent SCFA effects, with 2025 cross-sectional data confirming AD-specific plasma signatures.
    \nBelow is a summary of key 2024\u20132025 findings:<\/span><\/span><\/span><\/p>\n

     <\/p>\n

    \n\n\n\n\n\n\n\n\n\n
    \n
    Study Type\/Source<\/span><\/span><\/div>\n<\/th>\n
    		\n
    Key Findings<\/span><\/span><\/div>\n<\/th>\n
    		\n
    Model\/Population<\/span><\/span><\/div>\n<\/th>\n
    		\n
    Outcomes\/Implications<\/span><\/span><\/div>\n<\/th>\n<\/tr>\n
    \n
    Cross-Sectional Observational<\/span><\/span><\/span> (PMC, Jun 2025)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Elevated plasma acetate\/valerate and reduced butyrate in CI-AD (n=28) vs. controls (n=10) and non-AD impairment (n=29); valerate ratios positively correlate with amyloid PET (rho=0.35\u20130.59) and GFAP\/NFL (rho=0.45\u20130.59). Acetate distinguishes CI-AD from non-AD (AUC=0.954).<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Human cohorts (n=67)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    SCFAs as biomarkers for AD differential diagnosis; excess acetate links to inflammation, butyrate depletion to pathology.<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n
    \n
    Review: SCFAs-Microglia Pathway<\/span><\/span><\/span> (J Neuroinflammation, May 2025)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Butyrate suppresses A\u03b2-induced microglial activation (CD11b\/COX-2 \u2193) via HDAC\/NF-\u03baB inhibition; acetate reduces LPS-ERK\/JNK in BV-2 cells. GPR41\/43 KO worsens hippocampal neurogenesis; SCFAs reverse via defensive genes (B2m, Fgl2 \u2191). Dual effects: germ-free models show SCFAs \u2191 APOE, impair A\u03b2 phagocytosis.<\/span><\/span><\/div>\n<\/td>\n
    		\n
    APP\/PS1, 5xFAD mice; BV-2\/in vitro microglia<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Highlights dose\/stage dependency; supports targeted modulation to enhance M2 shift and clearance.<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n
    \n
    Preclinical: Butyrate Supplementation<\/span><\/span><\/span> (Chem Biol Interact, cited 2025 review)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Oral butyrate (4 weeks) upregulates GPR41, inhibits NF-\u03baB\/IL-1\u03b2 in A\u03b2-stimulated microglia, improves cognition in APP\/PS1 mice.<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Male APP\/PS1 mice<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Reduces neuroinflammation and A\u03b2; potential for HDAC-focused therapies.<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n
    \n
    Preclinical: Fiber\/SCFAs<\/span><\/span><\/span> (J Neurosci, cited 2025)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Dietary fiber boosts SCFAs, activates microglial FFAR2\/3, reduces plaques\/inflammation in 5\u00d7FAD; inulin restores TNF-\u03b1 to youthful levels in aged mice.<\/span><\/span><\/div>\n<\/td>\n
    		\n
    5xFAD and aged mice<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Prebiotics as non-invasive intervention; links low SCFAs to senescence markers (Ccl4, lgals3 \u2191).<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n
    \n
    Mechanistic: Propionate Effects<\/span><\/span><\/span> (ACS Chem Neurosci, 2024)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Propionate \u2193 microglial phagocytosis of fibrillar A\u03b2, maintains homeostatic phenotype without M2 shift.<\/span><\/span><\/div>\n<\/td>\n
    		\n
    A\u03b2-induced IMG microglia (in vitro)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Cautions against indiscriminate supplementation; low doses may impair clearance in early AD.<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n
    \n
    Microbiota-FMT<\/span><\/span><\/span> (Mol Nutr Food Res, cited 2025)<\/span><\/span><\/div>\n<\/td>\n
    		\n
    Clostridium butyricum<\/span><\/span><\/span> colonization \u2191 butyrate, inhibits microglial activation via GPR43 in APP\/PS1.<\/span><\/span><\/div>\n<\/td>\n
    		\n
    APP\/PS1 mice<\/span><\/span><\/div>\n<\/td>\n
    		\n
    FMT boosts SCFA-producers for anti-inflammatory effects.<\/span><\/span><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n


    \nHuman evidence is emerging:<\/strong>
    \nSalivary acetate\/propionate \u2191 in AD, correlating with periodontal risk; plasma SCFAs associate with brain acetate uptake in MCI.<\/span><\/span><\/span><\/p>\n

    Therapeutic Applications<\/strong>
    \n<\/span><\/span><\/span>SCFAs offer adjunctive strategies to target early AD dysbiosis, with 2025 reviews advocating precision interventions to leverage beneficial effects while mitigating risks like impaired phagocytosis.<\/span><\/span><\/span><\/p>\n