Gut Bacterial Metabolite-AhR Dysregulation Converts SCFA-Deficiency into IDO1-Driven Kynurenine Neurotoxicity
🧪 Overview
Aryl hydrocarbon receptor (AhR), expressed in microglia, astrocytes, and neurons, normally ligates tryptophan catabolites from gut bacteria (indole, indole-3-propionate). Dysbiosis depletes tryptophan-metabolizing commensals, reducing AhR ligand availability. Simultaneously, chronic neuroinflammation elevates IDO1, shunting tryptophan toward kynurenine pathway, producing quinolinic acid (NMDAR agonist) and ROS. SCFAs normally suppress IDO1 via GPR41/GPR43-STAT3 signaling, creating a protective deficit.
🧬 Mechanism
Curated pathway from expert analysis
flowchart TD
A["Tryptophan<br/>Metabolism"]
B["AHR Activation<br/>Transcription Factor"]
C["IDO1 / KYNU<br/>Kynurenine Pathway"]
D["KYNA Synthesis<br/>Neuroprotective Metabolite"]
E["QUIN Synthesis<br/>Neurotoxic Metabolite"]
F["GRIN2A Activation<br/>Excitotoxicity"]
G["STAT3<br/>Pro-inflammatory Signaling"]
H["Neuronal<br/>Excitotoxicity"]
A --> B
B --> C
C --> D
C --> E
D --> F
E --> F
B --> G
G --> H
F --> H
style A fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style D fill:#1b5e20,stroke:#a5d6a7,color:#a5d6a7
style E fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style H fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a⚖️ Evidence
No linked papers recorded for this hypothesis yet.
🏥 Translation
🧬 3D Protein Structure — AHR
No curated PDB or AlphaFold mapping for AHR yet. Search RCSB →
🧠 GTEx v10 Brain ExpressionJSON
Median TPM across 13 brain regions for AHR, IDO1, KYNU, HAAO, GRIN2A, STAT3 from GTEx v10.
💉 Clinical Trials
No clinical trials data linked to this hypothesis yet.
No curated ClinVar variants loaded for this hypothesis.
Run scripts/backfill_clinvar_variants.py to fetch P/LP/VUS variants.
No DepMap CRISPR Chronos data found for AHR, IDO1, KYNU, HAAO, GRIN2A, STAT3.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
🏆 Tournament
🏆 Arenas / Elo
📊 Market Indicators
💾 Resource Usage
No resource usage or linked notebooks recorded for this hypothesis yet.
🔮 Predictions
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF germ-free mice or antibiotic-induced dysbiosis mice are colonized with SCFA-producing commensals (e.g., Faecalibacterium prausnitzii, Roseburia intestinalis) or receive oral SCFA supplementation (b | Kynurenine/tryptophan ratio in prefrontal cortex will decrease from ~0.15 to <0.10; quinolinic acid levels will drop from ~800 pg/mg to <560 pg/mg; microglial I | — no observation — | pending | 0.72 |
| IF we stratify a cohort of 500 Parkinson's disease patients and 500 age-matched controls by fecal SCFA concentrations (low tertile vs. high tertile) and measure CSF kynurenine/tryptophan ratio and qui | Low-SCBA group will have mean CSF kynurenine/tryptophan ratio of 0.28 ± 0.09 vs. 0.16 ± 0.06 in high-SCBA group; quinolinic acid: 1250 ± 380 pg/mL vs. 595 ± 210 | — no observation — | pending | 0.68 |
▸Metadatasource: v1_phase_c_backfill · origin_type: debate_synthesizer
| source | v1_phase_c_backfill |
| origin_type | debate_synthesizer |
| _schema_version | 1 |