Medicine & Health

IF synthetic mitochondrial N-formyl peptide (fMLF; 10–100 nM, intracoronary micro-infusion over 60 seconds) is administered as a macropinocytosis-priming pre-treatment, followed immediately by intracoronary delivery of high-quality allogeneic donor mitochondria (10⁸ organelles/mL, isolated from young syngeneic skeletal muscle and quality-filtered by JC-1 membrane potential above 0.9 ΔΨm threshold) to aged (22–24 month) male C57BL/6J mice with documented cardiac mtDNA mutational burden, in the absence of surgical ischemia,

THEN donor mitochondrial retention at 7 and 28 days post-delivery will be significantly greater than in unprimmed allogeneic delivery controls (≥3-fold increase in absolute donor mtDNA copies by droplet digital PCR), and this retention will produce a measurable heteroplasmy shift (≥15% reduction in mutant:wildtype mtDNA ratio by long-range nanopore sequencing) in the left ventricular free wall, alongside ≥20% improvement in left ventricular ejection fraction (LVEF) by echocardiography compared to age-matched vehicle controls,

BECAUSE the following mechanistic cascade is proposed:

1. Aged cardiomyocytes accumulate clonally expanded mutant mtDNA (deletions and point mutations), impairing Complex I/IV activity and reducing ATP synthesis capacity — per the literature synthesis on MitoSENS damage accumulation described in the evidence set (McCully et al., American Journal of Physiology-Heart and Circulatory Physiology, as cited in evidence set).
2. Exogenous mitochondrial transplantation rescues this deficit, but uptake by cardiomyocytes is actin-dependent

IF sub-lethal digoxin (0.25 mg/kg IP every 48 hours for 14 days) is administered to aged male C57BL/6J mice (22–24 months) prior to a GPNMB peptide-adjuvant vaccine,

THEN flow cytometric mean fluorescence intensity (MFI) of surface GPNMB on circulating and tissue-resident p16⁺/SA-β-gal⁺ senescent cells will increase ≥1.8-fold above vehicle-treated aged controls by day 14, and subsequent vaccination will reduce p16⁺ senescent cell burden by ≥40% more than vaccination alone, measured by p16-3MR reporter luminescence and tissue immunofluorescence at day 42,

BECAUSE the following causal chain operates:

1. Digoxin inhibits the Na⁺/K⁺-ATPase α1 subunit on senescent cells, elevating intracellular Na⁺ and triggering reversal-mode Na⁺/Ca²⁺ exchange, producing a sustained intracellular calcium transient (cardiac glycosides canonically inhibit the Na⁺/K⁺-ATPase)[https://doi.org/10.1038/s42255-019-0122-z].
2. Elevated intracellular Ca²⁺ activates the phosphatase calcineurin, which dephosphorylates TFEB at Ser211, promoting its nuclear translocation and activation of the CLEAR (Coordinated Lysosomal Expression and Regulation) gene network [SPECULATIVE: direct calcineurin→TFEB→GPNMB axis not yet demonstrated for cardiac glycosides; inferred from established calcineurin-TFEB literature].
3. Ouabain's senolytic mechanism in BRAF-V600E senescent cells operates through Na,K-ATPase–dependent signal transduction engaging the autophagy-lysosomal axis, and cardiac glycosides restore autophagy flux in cellular stress models, confirming lysosomal pathway engagement (ouabain engages Na,K-ATPase–

IF a two-component AAV9 vector system encoding (1) a computationally redesigned MEF2C variant (hereafter "sMEF2C"), generated via RFdiffusion motif-scaffolding of the MADS-MEF2 domain (residues 1–86, anchored on PDB: 1EGW/6BYY backbone) followed by ProteinMPNN sequence optimization and AlphaFold2 structural validation — with mutations targeting the DNA-recognition α-helix for increased affinity at the CTA(A/T)₄TAG consensus and the hydrophobic cofactor-docking groove for enhanced p300/CBP recruitment and steric exclusion of class IIa HDACs — and (2) a dCas9-p300 fusion guided by a pool of three sgRNAs targeting H3K27me3-silenced promoter/enhancer regions of MYH6, TNNT2, and ACTC1 respectively, is delivered by direct intramyocardial injection (10¹¹ vg per construct) into aged C57BL/6J mice (18–22 months, both sexes) 72 hours after surgically induced myocardial infarction (LAD ligation), alongside wildtype GATA4 and TBX5 (GHMT backbone),

THEN the efficiency of direct cardiac fibroblast-to-induced cardiomyocyte (iCM) conversion will increase from the current 3–9% baseline observed with wildtype GMT/GHMT to ≥25% cTnT⁺/αMHC⁺ cells at 8 weeks post-delivery, with durable (≥12-week) genome-wide H3K27ac deposition and reciprocal H3K27me3 eviction confirmed at the three targeted loci, measurable by CUT&RUN and ATAC-seq, and accompanied by a ≥15% improvement in left ventricular ejection fraction (LVEF) by echocardiography relative to wildtype GMT/GHMT controls,

BECAUSE the following causal chain is supported by the evidence:

1. H3K27me3 marks deposited by EZH2 at *MYH

IF allogeneic bone marrow-derived mesenchymal stromal cells (MSCs; 1×10^6 cells per lobe, delivered via 29–30 gauge needle at a 30–45° angle under direct visualization following partial upper median sternotomy) preconditioned for 72 hours on decellularized aged (18-month-old C57BL/6 donor) thymic extracellular matrix scaffolds — prepared via three freeze-thaw cycles (−80°C/37°C) followed by sequential 1% Triton X-100 / 0.1% SDS detergent treatment and extensive PBS wash — are administered by intrathymic injection into 18–22 month-old C57BL/6 mice (both sexes, n=15 per group),

THEN at week 12 post-injection, the frequency of CD44^low CD62L^high cells among peripheral blood CD4^+ and CD8^+ T cells will reach ≥40% of 8-week-old reference controls (versus <20% in PBS vehicle controls), the splenic TCRβ CDR3 Shannon entropy index will increase by ≥0.3 units versus vehicle, and thymic cellularity at sacrifice will show a statistically significant increase in total thymocyte number versus aged vehicle — and critically, aged-ECM-preconditioned MSCs will outperform both PBS vehicle and naive (unconditioned) MSCs by ≥15 percentage points in naive T cell frequency recovery, with this superiority explained by the hypothesis that aged thymic ECM acts as a damage-specific molecular "blueprint" that calibrates the MSC secretome toward simultaneous anti-fibrotic and thymopoietic repair programming, an effect not recapitulated by naive MSCs or — as proposed in the novel extension — by MSCs conditioned on young thymic ECM,

BECAUSE the following step-by-step causal chain connects th

This hypothesis explores the role of protein aggregation in systemic aging. What does the evidence suggest, and how might we test it?

Hypothesis

We propose that serial measurement of the serum soluble CD30 (sCD30) to soluble CD26 (sCD26/DPP-IV) ratio, integrated with a T-cell receptor clonotype divergence index quantifying Th17/Treg lineage commitment asymmetry in peripheral blood, identifies patients with axial spondyloarthritis (axSpA) who will develop clinically significant peripheral joint involvement 6–14 months before conventional detection by tender/swollen joint counts or ultrasonographic synovitis.

Rationale

sCD30, a marker of Th2/activated T-cell turnover, and sCD26 (dipeptidyl peptidase-IV), which modulates chemokine bioactivity and Th1/Th17 polarization, reflect complementary arms of immune regulation. In axSpA, the transition from purely axial disease to mixed axial-peripheral phenotype represents a critical inflection in disease trajectory that determines treatment strategy (IL-17 inhibitors vs. TNF inhibitors vs. JAK inhibitors) and long-term outcomes.

Simultaneously, TCR sequencing of sorted Th17 (CCR6+CXCR3−) and Treg (CD25hiCD127lo) populations can quantify clonotype divergence — the degree to which these lineages are drawing from non-overlapping TCR repertoires. A rising divergence index suggests loss of peripheral tolerance checkpoints that may precede tissue-specific inflammation.

Testable Predictions

1. Primary: A composite biomarker combining sCD30/sCD26 ratio slope (>2 SD increase over 3 consecutive monthly measurements) with Th17/Treg clonotype divergence index (>0.65 on normalized Jaccard dissimilarity) will predict peripheral joint involvement with >80% sensit

This hypothesis explores an underappreciated dimension of cellular aging.

IF a mutant-selective allosteric inhibitor of the DNMT3A R882H/R878H homodimer interface at PDB: 6W8B (target affinity Ki ≤500 nM by SPR) is administered by oral gavage at 15 mg/kg/day for 12 weeks to 12-month-old Vav1-Cre; Dnmt3a-R878H/+ mice of both sexes, compared with age-matched vehicle-treated knock-in littermates and 6-month reference controls,

THEN bone-marrow Lin-Sca1+cKit+ (LSK) cells will decrease by at least 40% by flow cytometry, plasma IL-6 and TNF-α will decrease by at least 30% by Luminex, the peripheral CD11b+Gr1+ / CD3+B220+ ratio will shift toward 6-month control levels, competitive transplant engraftment from treated donors will fall, and targeted bisulfite-seq will show methylation recovery at p15INK4b and RASSF1A; an exploratory downstream effect should be reduction of mutant monocyte-derived microglial signatures in aged tissues.

BECAUSE:

1. The provided Research Context identifies DNMT3A R882H/R878H as creating a targetable neomorphic homodimer interface at PDB: 6W8B, with TR-FRET nominated as the direct target-engagement assay [provided Research Context; no DOI/URL in retrieved literature].
2. [SPECULATIVE] Disrupting this mutant interface will restore a more normal methylation program at CHIP-relevant tumor-suppressor loci such as p15INK4b and RASSF1A, which can be distinguished from nonspecific cytotoxicity by paired bisulfite-seq and viability assays [provided Research Context; no DOI/URL in retrieved literature].
3. [SPECULATIVE] Recovery of methylation at these loci will reduce the competitive fitness of already-expanded mutant HSC clones, le

IF a recombinant MyoAAV vector encoding a nuclear-optimized MOTS-c transgene placed under the transcriptional control of a synthetic Antioxidant Response Element (ARE)/NRF2-responsive promoter (MyoAAV-ARE-MOTS-c), delivered at ≥5×10¹³ vg/kg via bilateral intramuscular injection into the gastrocnemius and tibialis anterior, is administered to aged (22–24 month), male C57BL/6J mice with established sarcopenia,

THEN the following measurable outcomes will be observed compared to vehicle-injected aged controls at 12 weeks post-injection:

• ≥20% improvement in grip strength (force normalized to body mass)
• ≥15% increase in hindlimb muscle mass (gastrocnemius wet weight)
• Restored AMPK phosphorylation (pAMPK/AMPK ratio, western blot) to levels approximating 4–6 month reference animals
• Improved mitochondrial oxygen consumption rate (OCR, Seahorse XF) in isolated myofibers
• Re-engagement of stress-responsive nuclear gene programs (NRF2 target genes: HMOX1, NQO1, GCLC; quantified by RT-qPCR) will be observed,

BECAUSE the following step-by-step causal chain connects the intervention to the outcome:

1. Aged skeletal muscle accumulates a chronic MOTS-c signaling deficit. Endogenous MOTS-c levels decline markedly with age due to progressive deterioration in mitochondrial transcriptional and translational fidelity, eroding the retrograde nuclear-mitochondrial communication axis. This accumulated deficit — not merely future decline — underpins the established bioenergetic and proteostatic dysfunction of sarcopenic muscle. (MOTS-c age-related decline and sarcopenia association)[

IF a uPAR-specific chimeric antigen receptor is stably transduced into allogeneic human Vγ9Vδ2 γδ T cells (anti-uPAR CAR-γδ T cells), generating an inherently dual-sensing "AND-gate" senolytic living drug, and this product is administered as a single intravenous infusion (~5×10⁶ cells per mouse) to naturally aged (24-month-old) male and female C57BL/6 mice,

THEN durable multi-tissue clearance of uPAR⁺ senescent cells (≥60% reduction in p21⁺/p16⁺ co-positive cells by IHC at 6 months post-infusion) will be observed across the liver, visceral adipose tissue, lung, kidney, and hippocampal subgranular zone, accompanied by: restoration of hippocampal neurogenesis (≥40% increase in BrdU⁺/DCX⁺ cells in the SGZ); improved systemic metabolic function (reduced glucose tolerance AUC vs. aged controls); and a markedly safer cytokine release profile compared to conventional anti-uPAR αβ CAR-T cells — with no detectable graft-versus-host disease (GvHD), no grade ≥2 cytokine release syndrome, and no on-target off-tumor toxicity in uPAR-low healthy tissues —

BECAUSE the following causal chain is supported by cross-paper synthesis:

1. uPAR (PLAUR) is broadly and robustly upregulated on the surface of senescent cells across liver, lung, adipose, kidney, heart, and brain in aged mice, confirmed across three independent senescence models by comparative RNA-seq and protein profiling, providing a pan-tissue surface target for engineered cytolytic cells (uPAR broadly induced on senescent cells across tissues)[https://doi.org/10.1038/s41586-020-2403-9].

2. Conventional αβ CAR-T cells targeting

Core Hypothesis

Exposure to ultraviolet B (UVB) radiation from sunlight stimulates the synthesis of vitamin D in the skin, which in turn plays a critical role in calcium metabolism, immune function, and overall health.

This hypothesis has been registered as an on-chain IP-NFT and documented in a Molecule Data Room. See links below.

🔬 Discovered Mechanisms

Research into the sunlight–vitamin D pathway has revealed a precise, multi-step biological cascade:

1. Photochemical Conversion (Skin)

UVB radiation (~290–315 nm) converts 7-dehydrocholesterol in skin keratinocytes into previtamin D3, which thermally isomerizes to vitamin D3 (cholecalciferol). This identifies the skin as a primary endocrine organ for vitamin D hormone production.

2. Hepatic Hydroxylation

IF an anti-DPP4/CD26 antibody-drug conjugate (ADC) — constructed using a high-affinity, internalizing anti-human DPP4 monoclonal antibody conjugated via a protease-cleavable valine-alanine (Val-Ala) dipeptide linker to a pyrrolobenzodiazepine (PBD) dimer payload (analogous to SG3249/tesirine, drug-to-antibody ratio [DAR] 2) — is administered systemically (intravenous, 1–3 mg/kg, q2w × 3 cycles) or via local intra-adipose injection to aged (20–24 month) male and female C57BL/6J mice bearing high visceral fat burden (or, in Phase 1, to primary human adipose-derived stromal cells [hASCs] driven to senescence in vitro),

THEN a ≥50% selective depletion of DPP4-high senescent cells in visceral and subcutaneous white adipose tissue (WAT) — quantified by flow cytometry for DPP4⁺/p16^INK4a⁺/SA-β-gal⁺ co-positivity, and by single-cell RNA sequencing — will be observed at 4–8 weeks post-treatment compared to isotype-ADC-treated age-matched controls, accompanied by ≥30% reduction in adipose tissue SASP cytokines (IL-6, IL-8, MMP-3 by ELISA/Luminex), improved systemic insulin sensitivity (glucose tolerance test), and preserved non-senescent adipose progenitor cell viability (DPP4-low/negative fraction ≥85% survival),

BECAUSE the following mechanistic chain is operative:

1. DPP4/CD26 is transcriptionally induced and selectively enriched on the plasma membrane of senescent human cells — identified and validated by mass spectrometry of the senescent membrane proteome — making it a bona fide, accessible extracellular target that distinguishes senescent from non-senescent cells in human ad

IF AAV8-CYP27A1-F444A (gain-of-function variant; 1×10¹² vg, single tail-vein injection) is administered to 12-week-old male ApoE−/− mice on a Western diet,

THEN aortic plaque 7-KC burden will be reduced ≥50% by LC-MS/MS and aortic root lesion area ≥30% by Oil Red O at 24 weeks post-injection, and plasma HDL-associated 7-KC esters will be reduced ≥40% and aortic CYP7A1 activity (hepatic bile acid output) will be increased ≥2-fold, compared to AAV8-GFP controls,

BECAUSE the following causal chain operates across two anatomical compartments:

1. Macrophage lysosomal 7-KC is esterified by SOAT1 and exported selectively to HDL in peripheral/extra-hepatic cells, because those tissues lack robust oxidative machinery and rely on esterification as primary 7-KC handling. (7-KC esterification and HDL efflux as extra-hepatic clearance mechanism)[https://doi.org/10.1016/j.bbalip.2015.01.007] This makes HDL-7-KC esters a quantifiable biomarker of macrophage lysosomal 7-KC efflux.

2. Circulating HDL delivers 7-KC esters to the liver, where hepatic lipase and CETP activity release free 7-KC into hepatocytes — the primary site of sterol catabolism — making hepatic enzyme upregulation the ideal single intervention point for systemic 7-KC clearance. [SPECULATIVE: direct evidence that HDL-7-KC esters are preferentially hepatically catabolized is not yet in the evidence set.]

3. Recombinant CYP27A1 directly hydroxylates 7-KC to 7-KC-27OH and further oxidation products; the F444A mutation [SPECULATIVE: the specific F444A residue is inferred from structural analogy to CYP7A1 a

IF a multi-epitope mRNA–lipid nanoparticle (LNP) neoantigen vaccine — encoding a concatenated polyepitope construct of (a) 9–15-mer peptides spanning the DNMT3A R882H substitution optimized for both MHC class I (e.g., HLA-A*02:01) and MHC class II presentation, and (b) novel open-reading-frame (neoORF) peptides derived from the most recurrent TET2 frameshift/nonsense truncations — formulated with a TLR4 agonist adjuvant (MPLA) and administered intramuscularly (prime × 2, boost × 1 over 6 weeks) to aged (18–22 month), male and female C57BL/6 mice bearing confirmed high-variant-allele-frequency (VAF ≥ 10%) somatic Dnmt3a hotspot or Tet2 loss-of-function CHIP clones (induced by retroviral transduction or aged naturally),

THEN a ≥ 30% reduction in CHIP clone VAF in bone marrow and peripheral blood (measured by droplet digital PCR at 12 and 24 weeks post-vaccination), suppressed progression to myelodysplastic phenotype, reduced IL-1β/IL-6 systemic inflammatory burden, and emergence of mutation-specific tetramer-positive CD4⁺ and CD8⁺ T cell populations will be observed,

BECAUSE of the following mechanistic chain:

1. CHIP-derived CD14⁺ monocytes carrying DNMT3A and TET2 mutations constitutively upregulate MHC class II HLA genes relative to wild-type controls, making them intrinsically superior professional antigen-presenting cells for their own mutant-derived peptides — thereby creating a pre-existing, exploitable immunological vulnerability on the surface of the very clones to be eliminated. (Mutated cells mediate distinct inflammatory responses in clonal hematopoies

IF lysosome-targeted recombinant DNase II nanoparticles (lyso-DNase II; formulated as mannose-6-phosphate receptor-targeted lipid nanoparticles encapsulating recombinant human DNase II optimized for activity at pH 4.5–5.0, administered intravenously at 3 mg/kg twice weekly for 8 weeks) are administered to aged female C57BL/6J mice (22–24 months),

THEN a significant reduction (≥40%) in cytoplasmic mitochondrial DNA (mtDNA) burden within Lin⁻Sca1⁺cKit⁺ (LSK) HSCs, suppression of cGAS-STING-NFκB signaling, restoration of HSC long-term repopulation capacity to ≥60% of young controls in competitive transplantation assays, and reduction of myeloid-biased output will be observed,

BECAUSE the following causal chain operates:

1. Aged HSCs exhibit lysosomal hyperactivation that is paradoxically dysfunctional: despite elevated degradative enzyme activity, lysosomal membrane permeabilization and impaired substrate processing result in failure to degrade mitochondrial DNA delivered via mitophagy, causing cytoplasmic mtDNA accumulation (Mount Sinai group work: https://scholars.mssm.edu/en/publications/reversing-lysosomal-dysfunction-restores-youthful-state-in-aged-h/).

2. Aged cells accumulate extranuclear DNA that engages the autophagy-lysosome system for clearance; when this clearance fails, cytoplasmic DNA persists and activates innate immune sensing (extranuclear DNA accumulation drives senescence and inflammation via autophagy-lysosome processing failure)[https://doi.org/10.1111/acel.12901].

3. Leaked cytoplasmic mtDNA activates cGAS, producing cGAMP, which engages STING, trigg