SkillsMechanism: The combination of senolytics (D+Q) clears senescent cells, while lamivudine (3TC) inhibits LINE-1 reverse transcriptase, synergistically suppressing cGAS-STING activation from L1 cDNA, cf-mtDNA, and EV-L1 RNA. Readout: Readout: This leads to a ≥40% reduction in plasma type-I IFN signature, ≥30% depletion of EV LINE-1 RNA cargo, and a ≥50% reduction in L1 cDNA burden, improving cognition and reducing senescent cell burden by ≥40%.
IF oral lamivudine (3TC, 100 mg/kg/day via drinking water) combined with an intermittent senolytic regimen of dasatinib (5 mg/kg) plus quercetin (50 mg/kg) administered by oral gavage on a 2-days-on/28-days-off cycle (D+Q) is administered to aged C57BL/6J mice (20–22 months, both sexes) for 16 weeks,
THEN the following measurable outcomes will be observed relative to vehicle-treated aged controls:
- ≥50% reduction in hippocampal and cortical cytoplasmic LINE-1 (L1) cDNA burden (measured by slot-blot and L1-specific qPCR on cytoplasmic DNA fractions)
- ≥40% suppression of plasma type-I interferon (IFN-I) signature (Mx1, ISG15, IFIT1 by qRT-PCR and ELISA)
- ≥30% depletion of circulating extracellular vesicle (EV) LINE-1 RNA cargo (nanoparticle tracking analysis + EV-isolated RNA sequencing)
- Statistically significant rescue of hippocampus-dependent cognition toward young reference values (novel object recognition discrimination index and Barnes maze escape latency)
- Reduction in p21+/p16+ senescent cell burden in brain and liver by ≥40% (immunofluorescence + SA-β-gal)
BECAUSE the following step-by-step causal chain converges on synergistic suppression of cGAS-STING-driven neuroinflammation through two mechanistically independent inputs simultaneously repaired by the combination:
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Epigenetic derepression of LINE-1 in senescent cells generates the primary cytoplasmic cDNA insult. During biological aging, loss of heterochromatin integrity in senescent cells allows transcriptional reactivation of L1 retrotransposons. L1-encoded reverse transcriptase (ORF2p) converts this RNA into cytoplasmic cDNA, which is recognized by cGAS as a viral-like DAMP, activating STING and triggering a robust type-I IFN response that constitutes the inflammatory SASP. (L1 drives IFN in senescent cells and promotes age-associated inflammation, Nature 2019, cited in Evidence Set)
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Senescent cells independently release cell-free mitochondrial DNA (cf-mtDNA) as a second cGAS-STING activating input. Immunofluorescence and quantitative analysis in aged multi-organ tissues demonstrate that accumulating senescent cells are a principal source of cf-mtDNA with aging, and that senolytic clearance of these cells reduces cf-mtDNA-driven cGAS-STING-mediated inflammation and improves transplanted organ survival. (Senolytics prevent mt-DNA-induced inflammation and promote the survival of aged organs following transplantation)[https://doi.org/10.1038/s41467-020-18039-x]
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Senescent cells shed pro-aging extracellular vesicles loaded with LINE-1 RNA that propagate paracrine senescence by delivering L1 RNA to recipient cells. Upon EV uptake, this exogenous L1 RNA is reverse-transcribed into cDNA by ORF2p activity within the recipient cell's cytoplasm, converting naïve cells to a cGAS-STING-activated, IFN-I-secreting, senescent-like state—creating a self-amplifying inflammatory circuit that disseminates inflammaging systemically and across the blood-brain barrier. (LINE...
SENS category: GlycoSENS
Key references: • doi.org/10.1038/s41467-020-18039-x] • doi.org/10.1038/s41467-020-18039-x],
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