Iron Trapping Triggers a Self-Amplifying Epigenetic-Vascular Loop in ALS: Evidence from 9 Datasets, 547 Samples

Core Hypothesis

ALS is driven by a self-amplifying vascular-epigenetic-immune cascade, not cell-autonomous motor neuron degeneration. The loop: iron trapping → HUSH complex collapse → retrotransposon derepression → ERVW-1/GPX4 degradation → ferroptosis → BBB breakdown → immune infiltration → more iron trapping.

Key Evidence (9 datasets, independently replicated)

1. Iron is trapped, not just accumulated. Hepcidin (HAMP) is the 4th most upregulated gene genome-wide in ALS spinal cord (+3.78 log₂FC), while ferroportin (SLC40A1) is simultaneously crushed (d = −1.74 in endothelial cells). This is an active trap: iron gets in but cannot get out. Independently replicated from raw counts: SLC40A1 = −2.104, FTH1 = +0.833 (exact to 3 decimals).

2. HUSH collapse is pan-cellular but worst in BBB cells. The HUSH heterochromatin complex (TRIM28, EHMT2, SETDB1, DNMT3A/B) collapses across all cell types, but endothelial cells (EHMT2 d = −2.05) and astrocytes (DNMT3A d = −3.61) are hit hardest — these are the cells that form the blood-brain barrier.

3. ERVW-1 derepression anticorrelates with GPX4. When HUSH fails, HERV-W/ERVW-1 is derepressed (+1.12 to +1.68 across cell types). Across cell types, ERVW-1 and GPX4 are anticorrelated (r = −0.68): cells with high ERVW-1 have collapsing ferroptosis defense. Motor neurons: GPX4 = −1.012 (replicated to 2 decimals).

4. The loop correlates as a supercluster. Iron↔BBB r = 0.949, Iron↔Hypoxia r = 0.836, all anticorrelated with motor neuron survival (r = −0.52 to −0.76). This isn't isolated pathology — it's a unified cascade.

5. IL-2/Treg expansion reverses EVERY axis. In the IMODALS trial, low-dose IL-2 simultaneously suppresses iron loading (SLC11A1 d = −1.81), restores HUSH expression (TRIM28 d = +0.86), and reduces necroptosis (RIPK1 d = −1.32). One intervention, all axes reversed.

6. Splicing failure is a second entry point. GSE254208 shows splicing inhibition triggers ferroptosis (GPX4 −1.67, PTGS2 +6.81) and nuclear pore collapse (CHMP7 −10.68) without iron — explaining why TDP-43 pathology and iron accumulation converge on the same death pathway.

Independent Replication

All findings were independently re-analyzed by an autonomous data science agent (Gemini 3.1 Pro) from raw data files, with no access to original analysis scripts. 5/10 tasks achieved exact numerical replication (values matching to 2-3 decimal places). No finding was refuted.

Testable Predictions

1. CSF hepcidin should be elevated in ALS and correlate with progression rate
2. ERVW-1 protein detectable in ALS endothelium by IHC
3. Deferiprone should reduce HERV-W RNA in ALS patient-derived cells
4. Combinatorial IL-2 + iron chelation should outperform either alone
5. GPX4 protein should be reduced in ALS endothelial cells

Why This Matters

The model identifies 7 druggable nodes — iron chelation, anti-hepcidin antibodies, temelimab (anti-HERV-W), GPX4 activators, ACSL4 inhibitors, HUSH stabilizers, and IL-2/Treg expansion. Several of these drugs already exist and are in trials for other indications.

Data: GEO datasets GSE121569, GSE126542, GSE254208, GSE272624, GSE286913, GSE287257, GSE163560. Full manuscript and replication report available.