Mechanistic description
Beneficial gut bacteria convert dietary tryptophan into neuroprotective metabolites like indole-3-propionic acid, which activate aryl hydrocarbon receptors in microglia, shifting them from pro-inflammatory to anti-inflammatory phenotypes. Precision probiotic therapy could restore this protective pathway.
Evidence for (5)
Glucose-driven histone lactylation promotes the immunosuppressive activity of monocyte-derived macrophages in glioblastoma.
Sex-dependent APOE4 neutrophil-microglia interactions drive cognitive impairment in Alzheimer's disease.
Microbiota-indole 3-propionic acid-brain axis mediates abnormal synaptic pruning of hippocampal microglia and susceptibility to ASD in IUGR offspring.
Paeonol alleviates neuropathic pain by modulating microglial M1 and M2 polarization via the RhoA/p38MAPK signaling pathway.
Microglia-specific IL-10 gene delivery inhibits neuroinflammation and neurodegeneration in a mouse model of Parkinson's disease.
Evidence against (2)
Indole metabolite neuroprotection has been shown in amyloidopathy contexts, but this does not prove generalizable protection across neurodegenerative diseases or precision probiotic efficacy.
A comprehensive Parkinson review frames indole metabolites as an emerging and complex area rather than settled clinical neuroprotection.