Mosaic chromosomal alterations drive a pro‑inflammatory extracellular vesicle niche that fuels clonal hematopoiesis and tissue‑specific cancer risk
Hypothesis
Mosaic chromosomal alterations (mCAs) are not merely passive markers of aging‑associated genomic instability; they actively shape the tissue microenvironment by altering the cargo of extracellular vesicles (EVs) released from affected cells. Specific mCAs—particularly copy‑neutral loss of heterozygosity (cnLOH) and large deletions—lead to aberrant DNA fragment generation that is packaged into EVs and transferred to neighboring stromal and immune cells. This EV‑mediated DNA transfer triggers innate immune sensing (cGAS‑STING) and a chronic senescence‑associated secretory phenotype (SASP), creating an inflammatory niche that favors the expansion of clones with growth‑advantage alterations (e.g., +12, ‑Y, del(13q)).
Rationale
- Large‑scale cohorts show that expanded autosomal mCAs (>10% fraction) increase hematologic cancer risk >100‑fold, with the highest HR for CLL (HR=121.9)【https://pmc.ncbi.nlm.nih.gov/articles/PMC7685330/】.
- mCAs elevate lung cancer risk, especially in smokers and cnLOH carriers (OR up to 1.56)【https://pmc.ncbi.nlm.nih.gov/articles/PMC10435278/】.
- Deletions predominate over duplications and correlate with genomic instability (Spearman rho=0.386)【https://pmc.ncbi.nlm.nih.gov/articles/PMC3014828/】.
- Tissue‑specific expansion patterns (pancreas ↑23‑fold recombinant cells, skin stable) indicate that clonal expansion dynamics, not mutation rate, drive age‑related mCA accumulation【https://pmc.ncbi.nlm.nih.gov/articles/PMC3014828/】.
- Unexpectedly, CNV prevalence is higher in centenarians than middle‑aged individuals, suggesting context‑dependent adaptive roles【https://www.aging-us.com/article/101461/text】.
These observations imply that certain mCAs may be tolerated or even beneficial in specific contexts (e.g., longevity), while others become pathogenic when they alter EV composition and provoke inflammation.
Testable Predictions
- EV DNA content: Individuals with high‑fraction mCAs will have elevated levels of chromosomal DNA fragments (size 100‑500 bp) in circulating EVs compared to age‑matched controls.
- Inflammatory signature: EVs isolated from mCA‑high donors will induce stronger cGAS‑STING‑dependent IFN‑β and SASP cytokine (IL‑6, IL‑8) secretion in recipient macrophages in vitro.
- Clonal impact: Co‑culture of hematopoietic stem/progenitor cells (HSPCs) with EVs from mCA‑positive donors will increase the frequency of colonies harboring known driver alterations (e.g., JAK2 V617F, DNMT3A) relative to EVs from mCA‑low donors.
- In vivo validation: Mouse models engineered to carry a heterozygous chromosome‑12 cnLOH in hematopoietic cells will show increased EV‑associated DNA, heightened serum SASP factors, and accelerated development of CLL‑like disease when crossed with a Jak2^V617F background.
- Longevity exception: Centenarian‑derived EVs, despite containing CNVs, will fail to trigger cGAS‑STING activation, indicating protective modifications (e.g., DNA methylation or protein shielding) that prevent inflammatory signaling.
Experimental Approach
- Collect peripheral blood from stratified cohorts (young, old, centenarians, mCA‑high vs. mCA‑low based on SNP‑array).
- Isolate EVs via ultracentrifugation/size‑exclusion chromatography; quantify DNA using qPCR for Alu/L1 repeats and sequencing for fragment size distribution.
- Stimulate THP‑1 macrophages or primary murine macrophages with EVs; measure phospho‑TBK1/IRF3, IFN‑β, and SASP cytokines by ELISA and RNA‑seq.
- Perform colony‑forming unit (CFU) assays with HSPCs exposed to EVs; assess clonal outgrowth by single‑cell DNA sequencing.
- Generate CRISPR‑edited mice with inducible cnLOH on Chr12; longitudinally monitor EV DNA, serum cytokines, and hematologic malignancy.
Falsifiability
If EVs from mCA‑high individuals do not show increased chromosomal DNA content or fail to activate cGAS‑STING/SASP in recipient cells, the central mechanistic link is refuted. Likewise, if EV transfer does not alter clonal outgrowth of HSPCs or accelerate malignancy in mouse models, the hypothesis would be falsified.
Implications
Demonstrating an EV‑mediated inflammatory niche would reposition mCAs as active drivers of age‑related cancer predisposition, open avenues for diagnostic EV‑DNA biomarkers, and suggest therapeutic strategies targeting EV release, cGAS‑STING, or SASP components to mitigate clonal expansion and cancer risk in aging populations.