Hypothesis

We propose that age‑dependent loss of accessibility at NF‑κB binding sites in stem cell enhancers triggers a compensatory increase in cytosolic NF‑κB activity, priming the NLRP3 inflammasome and thereby linking chromatin erosion to chronic inflammation and stem cell dysfunction.

Mechanistic Model

• Step 1: Erosion of enhancer accessibility – ATAC‑seq shows decreased openness at enhancers near lineage‑specifying genes (e.g., PBX1, NAT1) in aged HSCs, MSCs and satellite cells {ATAC‑seq erosion in aged stem cells}.
• Step 2: Specific depletion of NF‑κB motifs – Motif analysis reveals that the lost peaks are enriched for NF‑κB consensus sequences, reducing basal sequestration of p65/p50 dimers at chromatin {TF motif enrichment}.
• Step 3: Cytosolic NF‑κB surge – With fewer chromatin docking sites, free NF‑κB accumulates in the cytoplasm, where it can be activated by ROS or lysosomal damage, leading to NLRP3 inflammasome assembly.
• Step 4: Inflammasome‑mediated inflammation – Active caspase‑1 cleaves IL‑1β and IL‑18, creating a paracrine inflammatory milieu that reinforces chromatin compaction via HDAC recruitment, establishing a vicious cycle.

Testable Predictions

1. Aged stem cells will show higher cytosolic NF‑κB p65 levels and increased NLRP3 inflammasome activity compared with young counterparts.
2. Restoring accessibility at NF‑κB‑rich enhancers (e.g., by CRISPR‑dCas9‑p300 epigenomic editing) will reduce cytosolic NF‑κB, lower inflammasome signaling, and improve lineage fidelity.
3. Pharmacological inhibition of NLRP3 (MCC950) will break the feedback loop, partially rescuing chromatin accessibility without directly altering DNA methylation.

Experimental Approach

• Use scATAC‑seq and scRNA‑seq on young vs. aged murine HSCs, intestinal stem cells, and muscle satellite cells to quantify NF‑κB motif loss {scATAC‑Ref database}.
• Measure cytoplasmic NF‑κB by subcellular fractionation and Western blot; assess inflammasome activation via ASC speck formation and caspase‑1 activity.
• Perform epigenomic editing with dCas9‑p300 targeted to eroded NF‑κB enhancers in aged HSCs (derived from GSE156910 human senescence data) {GSE156910 human senescence ATAC‑seq}.
• Evaluate functional outcomes: colony‑forming unit assays, differentiation bias, and transplantation efficacy.
• Apply MCC950 treatment in parallel cultures to test inflammasome dependence.

If predictions hold, the hypothesis links chromatin erosion to inflammasome‑driven inflammation, offering a mechanistic bridge between epigenetic aging and stem cell decline that can be therapeutically targeted.