Description
How does gut microbiome dysbiosis contribute to neuroinflammation and neurodegeneration through toll-like receptor TLR signaling and short-chain fatty acids SCFAs
Resolution criteria
Resolution requires: (1) Prospective interventional trial or well-controlled germ-free model establishing dose-response of microbiome dysbiosis on TLR4-mediated neuroinflammation: LPS levels in portal circulation correlate with hippocampal IL-1beta and microglial morphology changes (r>=0.6, n>=30 per condition); (2) SCFA loss-of-function: SCFA transporter knockout (Slc5a8) or antibiotic-induced depletion reduces brain butyrate by >=50% and increases neuroinflammatory markers by >=1.8-fold vs controls, with dose-response relationship established; (3) Clinical validation: human fecal microbiota transplant (FMT) from neurodegeneration patients to germ-free recipients reproduces CNS inflammation markers detectable in CSF (IL-6, TNF-alpha above 95th percentile of healthy donor FMT group). Correlation data from observational microbiome studies without causal manipulation is insufficient.
Evidence summary
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