Chronic NSAID use reduces prostaglandin E2 (PGE2) signaling, which in turn diminishes mitochondrial citrate export and ATP‑citrate lyase (ACLY) activity, lowering nuclear acetyl‑CoA pools. Reduced acetyl‑CoA limits histone acetylation, especially H3K27ac, and shifts the epigenetic landscape toward a pattern seen in accelerated aging. This hypothesis predicts that long‑term NSAID users will show higher epigenetic age (e.g., GrimAge) and lower nuclear acetyl‑CoA/H3K27ac levels compared with age‑matched non‑users, independent of underlying pain status.

Mechanistic Rationale

• PGE2 binds EP2/EP4 receptors → Gs → ↑cAMP → PKA activation → phosphorylation and activation of ACLY in cytosol and nucleus.
• Active ACLY cleaves citrate to acetyl‑CoA + oxaloacetate, feeding cytosolic and nuclear acetyl‑CoA pools.
• Nuclear acetyl‑CoA is the substrate for histone acetyltransferases (p300/CBP) that deposit H3K27ac at enhancers of DNA‑damage‑response and metabolic genes.
• Reduced H3K27ac leads to tighter chromatin, diminished transcription of repair genes, and increased recruitment of DNA methyltransferases (DNMT3A/B) at CpG islands.
• The resulting epigenetic drift mirrors clocks such as GrimAge, which weigh methylation at sites linked to smoking, plasma proteins, and aging‑related phenotypes.

Experimental Design

1. Cohort assembly – Recruit three groups of adults aged 50‑75: (i) chronic NSAID users (≥6 months daily ibuprofen or celecoxib), (ii) pain‑matched controls using acetaminophen (non‑COX‑2 inhibitor), and (iii) healthy controls with no regular analgesic use. Target n=150 per group to detect a 0.5‑year difference in GrimAge with 80% power.
2. Baseline measurements – Collect fasting blood for plasma PGE2 (ELISA), nuclear acetyl‑CoA (LC‑MS from isolated nuclei), global H3K27ac (Western blot and ChIP‑seq for H3K27ac at promoters of TP53, SOD2, and PPP1CA), oxidative stress marker 8‑iso‑PGF2α, hemoglobin, and a comprehensive pain questionnaire (VAS, WOMAC).
3. Epigenetic aging – Generate genome‑wide methylation arrays (EPIC) and compute multiple clocks (Horvath, Hannum, GrimAge, PhenoAge).
4. Intervention arm – In a subset of NSAID users, randomize to 4‑week add‑on of sodium acetate (1.5 g/day) or PGE2 analog (misoprostol low dose) versus placebo, with repeat measurements of nuclear acetyl‑CoA, H3K27ac, and epigenetic age.
5. Cell‑culture validation – Treat primary human fibroblasts with ibuprofen (100 µM) ± PGE2 (10 nM) or acetate (5 mM) for 48 h; assess ACLY phosphorylation (Western), nuclear acetyl‑CoA, H3K27ac, and senescence‑associated β‑galactosidase.

Predictions

• Plasma PGE2 will positively correlate with nuclear acetyl‑CoA levels (r > 0.4, p < 0.001).
• NSAID users will exhibit ~15 % lower H3K27ac at DNA‑repair gene promoters and a GrimAge acceleration of 0.8‑1.2 years relative to controls, independent of pain scores.
• Acetate or PGE2 rescue will restore nuclear acetyl‑CoA and H3K27ac to control levels and blunt GrimAge acceleration in vitro.
• Acetaminophen users will not show the acetyl‑CoA/H3K27ac deficit, isolating the COX‑2‑dependent effect.

Potential Confounders

• Oxidative stress and gastrointestinal blood loss will be measured and included as covariates in regression models.
• Lifestyle factors (diet, exercise, smoking) will be recorded and matched or adjusted for.
• Sub‑analysis will exclude participants with liver or renal impairment that could alter acetyl‑CoA metabolism.

Falsification If chronic NSAID users show no significant difference in nuclear acetyl‑CoA, H3K27ac, or epigenetic age compared with controls, or if plasma PGE2 fails to predict these markers, the hypothesis is refuted. Conversely, a clear dose‑dependent link between NSAID exposure, reduced PGE2, lowered nuclear acetyl‑CoA/H3K27ac, and increased GrimAge would support the idea that analgesic‑induced prostaglandin suppression, rather than pain silencing, contributes to accelerated biological aging.