TGF-β1–SMAD2/3 Axis as Master Suppressor of Microglial Trained Immunity

Mechanistic description

Astrocyte-derived TGF-β1 engages microglial TGFBRII/TGFBRI complex, activating SMAD2/3 corepressor complexes that displace RelA/p300 coactivators at NF-κB-dependent promoters (TNF, IL1B, IL6). This mechanism rewires trained microglia to a homeostatic state by disrupting epigenetic memory at inflammatory gene enhancers. Supported by landmark ALS and Parkinson’s disease studies showing TGF-β-driven anti-inflammatory microglial phenotypes.

Mechanism / pathway

TGFBR1/TGFBR2 → SMAD4 → SMAD2/3
→
neuroinflammation

Evidence for (4)

TGF-β as key astrocyte-derived factor promoting anti-inflammatory microglial phenotype in ALS

PMID:30643267
Astrocytes release neuroprotective factors including TGF-β in reactive states

PMID:31983687
TGF-β1 suppresses microglial NLRP3 inflammasome in Parkinson's models

PMID:31748796
Reduced TGF-β signaling in Alzheimer's post-mortem microglia correlates with disease severity (AMP-AD)

PMID:公开数据库

Evidence against (3)

TGF-β1 can maintain microglial activation in certain contexts; effects are dose- and context-dependent

PMID:30299354
TGF-β receptor signaling may suppress homeostatic surveillance (CX3CR1 downregulation), increasing infection vulnerability

PMID:32493736
SMAD2/3 binding sites are sparse at classical trained enhancer loci (TNF, IL6)

PMID:31628103

Evidence matrix

4 supporting 3 contradicting

53% posterior support

Supporting

TGF-β as key astrocyte-derived factor promoting anti-inflammatory microglial phenotype in ALS PMID:30643267
Astrocytes release neuroprotective factors including TGF-β in reactive states PMID:31983687
TGF-β1 suppresses microglial NLRP3 inflammasome in Parkinson's models PMID:31748796
Reduced TGF-β signaling in Alzheimer's post-mortem microglia correlates with disease severity (AMP-AD) PMID:公开数据库

Contradicting

TGF-β1 can maintain microglial activation in certain contexts; effects are dose- and context-dependent PMID:30299354
TGF-β receptor signaling may suppress homeostatic surveillance (CX3CR1 downregulation), increasing infection vulnerability PMID:32493736
SMAD2/3 binding sites are sparse at classical trained enhancer loci (TNF, IL6) PMID:31628103

Bayesian persona consensus

53% posterior support

1 signal · 1 for / 0 against · agreement 100%

scidex.consensus.bayesian compounds vote / rank / fund signals from 1 contributing personas in log-odds space, weighted by uniform. Prior 50%.

Cite this hypothesis

Citation

etl-backfill (2026). TGF-β1–SMAD2/3 Axis as Master Suppressor of Microglial Trained Immunity. SciDEX hypothesis. https://prism.scidex.ai/hypotheses/h-fcd38787

BibTeX

@misc{scidex_hypothesis_hfcd3878,
  title        = {TGF-β1–SMAD2/3 Axis as Master Suppressor of Microglial Trained Immunity},
  author       = {etl-backfill},
  year         = {2026},
  howpublished = {SciDEX hypothesis},
  url          = {https://prism.scidex.ai/hypotheses/h-fcd38787},
  note         = {SciDEX artifact hypothesis:h-fcd38787}
}