SkillsMechanism: Intermittent fasting activates autophagy in aged HSCs while senolytics clear senescent thymic cells, creating a permissive environment for immune rejuvenation. Readout: Readout: Naïve CD4+ T-cell output increases by ≥70%, plasma IL-6 and TNF-α levels decrease by ≥50%, and antigen-specific IgG titers achieve young control levels.
Hypothesis
Intermittent fasting (IF) enhances the efficacy of senolytic drugs in reversing immunosenescence by simultaneously rejuvenating hematopoietic stem cell (HSC) niches and thymic stromal function.
Mechanistic Rationale
- IF activates autophagy in aged HSCs, reducing myeloid skewing and restoring lymphoid potential [1].
- Senolytics (e.g., dasatinib + quercetin) eliminate senescent thymic epithelial cells, lowering local SASP and permitting IL‑7‑driven thymopoiesis [2].
- Combined, IF‑induced autophagy clears intracellular damage while senolytics remove the inflammatory niche, creating a permissive environment for naïve T‑cell output and reducing circulating pro‑inflammatory cytokines.
Testable Predictions
- In 20‑month‑old mice, IF alone will increase autophagy markers (LC3‑II) in HSCs by ~30 % but will not significantly alter senescent cell burden in the thymus.
- Senolytic treatment alone will decrease thymic p16^INK4a^‑positive cells by ~40 % without changing HSC autophagy.
- The IF + senolytic combination will:
- Raise naïve CD4^+ T‑cell output from the thymus by ≥70 % relative to baseline.
- Lower plasma IL‑6 and TNF‑α levels by ≥50 %.
- Improve response to a novel antigen (e.g., OVA) measured by antigen‑specific IgG titers, achieving titers comparable to 6‑month‑old controls.
- Either monotherapy will produce ≤30 % improvements on these endpoints.
Experimental Design
- Groups (n=10 per group): young control, aged control, aged + IF (20 % alternate‑day fasting), aged + senolytic (dasatinib 5 mg/kg + quercetin 50 mg/kg weekly), aged + IF + senolytic.
- Duration: 12 weeks.
- Readouts: flow cytometry for lineage‑negative Sca‑1^+c‑Kit^+ (LSK) HSCs, autophagy flux (LC3‑II/I, p62), thymic senescence (p16^INK4a^, SA‑β‑gal), peripheral naïve/memory T‑cell ratios, cytokine plasma ELISA, vaccine challenge.
Falsifiability
If the IF + senolytic group fails to show a statistically significant synergistic increase (defined as > additive effect of monotherapies) in naïve T‑cell output or cytokine reduction, the hypothesis is refuted. Conversely, a clear synergistic benefit supports the notion that metabolic rejuvenation and senescent cell clearance are interdependent levers for reversing immunosenescence.
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