Hypothesis

Persistent intestinal barrier leakage allows microbial products to enter circulation, where they activate the cGAS‑STING pathway in circulating CD8⁺ T cells. This activation drives a senescent phenotype marked by a SASP rich in CXCL10 and IL‑6, which in turn further damages the epithelial barrier through STAT1‑dependent tight‑junction disruption. Consequently, a self‑reinforcing gut‑immune loop accelerates systemic inflammaging and immunosenescence. We propose that a combined regimen of intermittent fasting, specific prebiotic fiber (e.g., inulin‑type fructans), and timed aerobic exercise will restore barrier integrity, reduce microbial translocation, and lower cGAS‑STING activation more effectively than senolytic monotherapy, thereby breaking the loop at its source.

Mechanistic Rationale

1. Barrier leakage and microbial translocation – Chronic low‑grade endotoxemia raises circulating LPS, which engages TLR4 on immune cells and triggers NF‑κB signaling, priming cells for senescence 1.
2. cGAS‑STING activation – Cytosolic DNA from bacterial debris or mitochondrial damage activates cGAS‑STING, leading to IRF3‑driven transcription of CXCL10 and IL‑6, a SASP signature distinct from the classic IL‑1α/IL‑1β profile 4.
3. SASP‑mediated barrier damage – Secreted CXCL10 binds CXCR3 on epithelial cells, altering actin cytoskeleton and decreasing occludin expression, thereby increasing permeability 5.
4. Holistic interventions – Intermittent fasting elevates NAD⁺ and SIRT1 activity, enhancing DNA repair and suppressing cGAS‑STING; prebiotic fiber fuels SCFA‑producing bacteria that strengthen tight junctions via GPR43 signaling; aerobic exercise boosts autophagy and IL‑10 production, shifting the IL‑10/IL‑6 ratio toward anti‑inflammatory states 2 3.
5. Senolytic limitation – Senolytics clear existing SASP⁺ cells but do not impede continual generation of new senescent cells driven by ongoing barrier leakage 1 4.

Testable Predictions

• In a randomized controlled trial, participants receiving the combined fasting‑fiber‑exercise protocol will show a ≥30% reduction in serum LPS‑binding protein and a ≥25% decrease in circulating CXCL10⁺ CD8⁺ T cells after 12 weeks, whereas the senolytic arm will show no significant change in these markers.
• Fecal SCFA concentrations will rise proportionally with improvements in tight‑junction marker (zonulin) expression, correlating with reduced SASP markers.
• The IL‑10/IL‑6 ratio will increase only in the holistic arm, predicting slower accumulation of senescence‑associated β‑galactosidase⁺ cells in peripheral blood mononuclear cells.
• Combining senolytics with the holistic regimen will not produce additive benefits over the holistic arm alone, indicating that upstream barrier restoration is the dominant factor.

Falsifiability

If the holistic protocol fails to lower serum LPS, CXCL10⁺ T cells, or improve barrier markers compared with senolytics, or if senolytics outperform the combined approach in reducing SASP burden, the hypothesis is refuted.