Hypothesis

Chronic accessibility of the DUSP10 enhancer in aged memory CD8+ T cells drives a paracrine signal that reprograms hematopoietic stem cells (HSCs) toward increased chromatin openness and myeloid skewing. Inhibiting this enhancer will normalize HSC epigenetics and reduce aging‑associated inflammation.

Rationale

• ATAC‑seq shows that the defining chromatin signature of human immune aging is gained accessibility at inflammatory loci like DUSP10 in memory CD8+ T cells 1.
• DUSP10 encodes a MAPK phosphatase that, when overexpressed, skews cytokine production toward IL‑6 and TNF‑α, factors known to activate RhoA signaling in HSCs 3.
• Elevated RhoA activity in aged HSCs correlates with global chromatin opening, a hallmark of intrinsic HSC aging that can be reversed by RhoA inhibition 2.
• Immune‑derived inflammatory pathways are upregulated across multiple tissues during aging, suggesting a systemic effector role 4.
• Loss of multilineage priming accessibility in HSCs links epigenetic drift to reduced regenerative capacity 5.

Together, these observations suggest a feed‑forward loop: DUSP10‑driven cytokine release from CD8+ T cells activates RhoA in HSCs, opening chromatin and locking cells into a myeloid‑biased, inflammatory state that further fuels immune dysregulation.

Predictions

1. CRISPRi‑mediated silencing of the DUSP10 enhancer in purified memory CD8+ T cells from old donors will decrease IL‑6 and TNF‑α secretion.
2. Conditioned media from edited T cells will reduce RhoA‑GTP levels in cultured young HSCs.
3. HSCs exposed to edited T‑cell conditioned media will show decreased global ATAC‑seq signal at promoters of myeloid genes and increased accessibility at lymphoid‑associated loci.
4. In vivo, adoptive transfer of edited T cells into aged mice will lower circulating inflammatory cytokines, reduce HSC chromatin accessibility (measured by ATAC‑seq on sorted Lin‑Sca1+‑cKit+ cells), and shift myeloid‑to‑lymphoid output toward youthful ratios.

Experimental Design

In vitro

• Isolate CD8+CD45RO+ T cells from peripheral blood of donors >65 y and <30 y (controls).
• Deliver CRISPRi (dCas9‑KRAB) targeting the DUSP10 enhancer via lentivirus; include non‑targeting gRNA control.
• After 72 h, measure cytokine secretion (ELISA) and confirm enhancer accessibility loss by ATAC‑seq or qPCR‑based accessibility assay.
• Collect conditioned media, treat CD34+ HSCs from cord blood, assess RhoA‑GTP pull‑down, phospho‑MYPT1 (Western), and perform ATAC‑seq after 48 h.

In vivo

• Use 20‑month‑old C57BL/6 mice; isolate memory CD8+ T cells, transduce ex vivo with CRISPRi‑DUSP10 or control, then inject 1×10^6 cells retro‑orbitally.
• After 2 weeks, collect serum for cytokine multiplex, bone marrow for HSC phenotyping (LSK, CD150+, CD48‑), and perform ATAC‑seq on sorted HSCs.
• Quantify myeloid (Gr‑1+Mac‑1+) vs lymphoid (B220+, CD3+) cells in blood and spleen.
• Include groups receiving aged control T cells and young T cells as baselines.

Potential Outcomes

• Supportive: Edited T cells show lowered IL‑6/TNF‑α, HSCs exhibit reduced RhoA activity, chromatin accessibility shifts toward a youthful pattern (decreased myeloid gene promoters, increased lymphoid enhancers), and peripheral blood displays improved lymphoid‑myeloid balance.
• Refutant: No change in cytokine output, HSC epigenetics, or lineage output despite confirmed enhancer silencing, indicating DUSP10 is not the critical mediator or that additional signals sustain the loop.

Implications

If validated, this hypothesis positions a specific epigenetic node in memory T cells as a programmable lever to reset hematopoietic aging. It reframes immune‑driven aging as a targetable circuit rather than a global decline, offering a precise intervention point for chromatin‑based rejuvenation therapies.

Key References

[1] Human immune aging chromatin signature in CD8+ T cells – pmc5626401 [2] RhoA inhibition reverses HSC chromatin opening – doi:10.1101/2025.04.23.647902 [3] Epigenetic remodeling in immune cells drives systemic aging – pmc6351880 [4] Immune pathway up‑regulation widespread in aging tissues – doi:10.1101/gr.240093.118 [5] HSC multilineage priming loss with age – pmc7789351