FFAR3 and Alzheimer disease: Beyond alleviating AD progression by repairing the intestinal barrier (Section 3.1) and inhibiting neuroinflammation (Section 3.5), its metabolite propionate has also been shown to regulate mitochondrial fission and autophagy through GPR41/43 receptors, maintaining neuronal mitochondrial homeostasis and thereby ameliorating Aβ-induced neurotoxicity, adding another significant mechanistic dimension to the protective role of A. muciniphila in AD (Wang et al., 2025).