Hypothesis

Intermittent administration of a low-dose mTOR inhibitor (e.g., rapamycin) aligned with the late-fasting phase of time-restricted eating (TRE) will potentiate senolytic clearance of senescent cells by boosting TFEB-mediated lysosomal biogenesis, thereby enhancing degradation of senolytic-induced apoptotic debris and extending healthspan beyond that achieved by senolytics + TRE alone.

Mechanistic Rationale

Senolytics such as dasatinib plus quercetin (D+Q) induce apoptosis in senescent cells, generating intracellular debris that must be cleared to prevent secondary inflammation [[https://doi.org/10.1038/s41591-018-0092-9]]. TRE upregulates autophagy markers LC3A, ATG12 and SIRT1, and raises β‑hydroxybutyrate, which further stimulates autophagic flux [[https://pmc.ncbi.nlm.nih.gov/articles/PMC7616065/]]. However, autophagy alone may insufficiently handle the bulk of apoptotic bodies released after senolytic dosing.

Recent work shows that fasting‑activated TFEB translocates to the lysosome, driving expression of lysosomal hydrolases and membrane proteins, thereby expanding degradative capacity [[https://doi.org/10.1016/j.cell.2020.05.018]]. mTORC1 directly phosphorylates TFEB, retaining it in the cytoplasm; thus, transient mTOR inhibition during the fasting window releases TFEB, synergizing with TRE‑induced lysosomal priming.

We propose that a brief rapamycin pulse (e.g., 1 mg/kg oral, 2 h before the end of a 16‑h fast) will:

1. Temporarily inhibit mTORC1, permitting TFEB nuclear translocation.
2. Amplify lysosomal biogenesis and cathepsin activity beyond the baseline TRE effect.
3. Enhance phagolysosomal degradation of senolytic‑generated apoptotic bodies, reducing proinflammatory spillover.
4. Lower the effective senolytic dose required for comparable senescent cell depletion, mitigating off‑target toxicity.

Testable Predictions

1. Biomarker level – In human peripheral blood mononuclear cells (PBMCs) from aged volunteers, the combination TRE + intermittent rapamycin + low‑dose D+Q will produce a greater increase in lysosomal markers (LAMP1, CTSB) and a larger decrease in senescence‑associated secretory phenotype (SASP) factors (IL‑6, IL‑8) than TRE + D+Q alone.
2. Cellular clearance – Using a senescent‑cell reporter mouse model (p16‑3MR), the triple regimen will reduce p16‑positive cell burden by >50 % more than D+Q + TRE after four weekly cycles.
3. Functional outcome – Treated mice will show improved grip strength and treadmill endurance relative to D+Q + TRE controls, correlating with lysosomal activity readouts.
4. Falsifiability – If rapamycin administration does not further increase LAMP1/CTSB expression or senescent‑cell depletion beyond TRE + D+Q, the hypothesis is falsified.

Experimental Design

• Human pilot (n=30, aged 65‑80, randomized, double‑blind, crossover): 4‑week cycles of (a) TRE alone, (b) TRE + D+Q (standard intermittent dose), (c) TRE + D+Q + low‑dose rapamycin (timed as above). Primary endpoints: plasma SASP panel, PBMC lysosomal gene expression (qPCR), and circulating cell‑free DNA as a proxy for apoptotic debris clearance. Secondary: physical performance (Short Physical Performance Battery).
• Mouse validation (p16‑3MR, n=15/group): identical dosing schedule adapted to murine metabolism. Longitudinal imaging of senescent‑cell burden via bioluminescence, lysosomal activity assay (Magic Red cathepsin B) in spleen/liver, and frailty index.

Potential Confounds and Controls

• Rapamycin’s immunosuppressive effects could independently affect inflammation; include a rapamycin‑only control arm to isolate lysosomal contribution.
• Variability in fasting adherence; monitor β‑hydroxybutyrate levels to confirm metabolic state.
• Off‑target senolytic toxicity; assess liver/kidney function tests.

Conclusion

By positioning mTOR inhibition at the metabolic peak of TRE, we exploit a natural checkpoint that couples nutrient sensing to lysosomal capacity. This mechanistic synergy should sharpen senolytic action, offering a concrete, falsifiable route to surpass the healthspan gains of current senolytic + TRE strategies and providing a platform for further damage‑repair interventions targeting other SENS pillars.