Hypothesis

Intermittent senolytic treatment triggers a lasting metabolic shift in surviving cells that suppresses SASP through AMPK‑dependent mitochondrial uncoupling, independent of continued drug presence.

Rationale

Senolytics such as dasatinib plus quercetin (D+Q) reduce senescent cell burden to ~6% in tissues, yet systemic benefits persist beyond the clearance window 1. This suggests that senolytics may remodel the microenvironment or reprogram non‑senescent cells to maintain a low‑SASP state. AMPK activation is known to inhibit NF‑κB signaling and promote mitochondrial fidelity, both of which attenuate SASP 4. Mitochondrial uncoupling, a downstream effect of AMPK, lowers ROS production and limits the inflammasome activation that fuels SASP 5. We propose that senolytics induce a transient AMPK surge that locks cells into a metabolically tolerant, SASP‑low phenotype through epigenetic remodeling of SASP promoters.

Testable Predictions

1. Mice treated with an intermittent D+Q regimen will show elevated phospho‑AMPK (Thr172) and increased mitochondrial uncoupling protein (UCP2/3) expression in tissues 7 days after the final dose, correlating with reduced SASP markers (IL‑6, IL‑1β, MMP‑3).
2. Pharmacologic inhibition of AMPK (Compound C) administered during the senolytic window will abolish the long‑term SASP suppression despite equivalent senescent cell clearance.
3. Overexpression of a dominant‑negative AMPK subunit in endothelial cells will prevent the persistence of low SASP levels after senolytic clearance, leading to rapid frailty recurrence.
4. Metabolomic profiling will reveal increased NAD⁺/NADH ratio and elevated TCA‑cycle intermediates in treated tissues, indicative of a shifted metabolic state.

Experimental Approach

• Animal model: Aged (20‑month) C57BL/6 mice receive either vehicle, single D+Q dose, or three intermittent D+Q doses (weekly ×3). Tissues (aortic endothelium, adipose, hippocampus) harvested at 24 h, 72 h, and 7 days post‑last dose.
• Readouts: Western blot for p‑AMPK, total AMPK, UCP2/3; ELISA for SASP cytokines; senescence‑associated β‑gal staining; flow cytometry for senescent cell markers (p16^INK4a^).
• Intervention arms: Sub‑groups receive Compound C (AMPK inhibitor) or vehicle during the senolytic window; separate cohorts undergo endothelial‑specific AMPK knockdown via AAV‑CRISPR.
• Analysis: Two‑way ANOVA with post‑hoc Tukey test; correlation analysis between p‑AMPK levels and SASP suppression.

Falsifiability

If intermittent senolytic dosing fails to produce sustained AMPK activation or mitochondrial uncoupling, or if AMPK inhibition does not attenuate the prolonged SASP reduction, the hypothesis is refuted. Conversely, observing the predicted metabolic and signaling changes that persist after senescent cell clearance would support the mechanism.

This hypothesis extends the current view of senolytics as mere clearance agents by proposing that they imprint a durable metabolic program that keeps the SASP silenced, offering a new avenue for optimizing hit‑and‑run dosing and minimizing off‑target effects.