Cristae Stabilization as a Gatekeeper of Mitochondrial DNA‑Driven Inflammaging

Hypothesis

Stabilizing mitochondrial inner‑membrane cristae blocks minority mitochondrial outer membrane permeabilization (miMOMP), thereby preventing cytosolic mtDNA release and downstream cGAS‑STING‑mediated inflammaging without compromising basal ATP production.

Mechanistic Rationale

Cristae architecture regulates the accessibility of BAX/BAK to the outer membrane. Tight cristae junctions, maintained by OPA1 and the MICOS complex, sequester cytochrome c and limit BAK oligomerization, reducing the probability of miMOMP【https://pmc.ncbi.nlm.nih.gov/articles/PMC12620326】. When cristae remodel upon stress, junctions widen, allowing BAX/BAK to accumulate at contact sites and trigger miMOMP, releasing mtDNA into the cytosol where it activates cGAS‑STING and drives the SASP【https://doi.org/10.1101/gad.331272.119】. Pharmacologic agents that reinforce cristae (e.g., SS‑31 peptide or OPA1‑activating small molecules) should therefore raise the threshold for miMOMP, attenuating inflammaging while preserving oxidative phosphorylation.

This idea extends the observation that ρ0 cells lacking mtDNA do not senesce【https://pmc.ncbi.nlm.nih.gov/articles/PMC12727128】by suggesting that the presence of mtDNA is only pathogenic when it can escape via miMOMP, a process gated by cristae state. It also reconciles why some models show high mtDNA mutation loads without respiratory decline【https://www.sciencedaily.com/releases/2025/05/250527135239.htm】: the mutations matter less than the membrane dynamics that permit their release.

Experimental Design

1. Cell model – Primary human dermal fibroblasts induced to senesce by low‑dose etoposide (10 µM, 24 h).
2. Intervention – Treat parallel cultures with SS‑31 (1 µM) or an OPA1‑activating compound (e.g., BGP‑15) versus vehicle control.
3. Readouts (48 h post‑treatment):
   • Cytosolic mtDNA measured by qPCR of mitochondrial genes in the cytosolic fraction【https://doi.org/10.15252/embj.201592862】.
   • cGAMP levels via ELISA.
   • SASP cytokine secretion (IL‑6, IL‑8) by Luminex.
   • Senescence markers (SA‑β‑gal, p16^INK4a^).
   • Mitochondrial respiration (Seahorse OCR) to confirm ATP production is unchanged.
4. Controls – ρ0 fibroblasts (mtDNA‑depleted) to verify assay specificity; BAX/BAK double‑KO cells to confirm miMOMP dependence.

Predicted Outcomes and Falsifiability

If cristae stabilization raises the miMOMP threshold, we expect:

• Significant reduction in cytosolic mtDNA (≥50 % drop vs control).
• Corresponding decrease in cGAMP and SASP cytokines.
• Lower SA‑β‑gal and p16 expression, indicating attenuated senescence.
• Basal OCR and ATP‑linked respiration remain within 10 % of vehicle‑treated cells.

Conversely, if SS‑31 or OPA1 activation fails to lower cytosolic mtDNA or SASP despite verified cristae tightening (assessed by EM or MT‑GFP microscopy), the hypothesis is falsified. Likewise, if inflammaging is suppressed but ATP production collapses, the claim that the intervention specifically uncouples inflammaging from bioenergetic failure would be unsupported.

Broader Implication

Targeting cristae stability offers a tractable upstream lever to modulate the mitochondrial DNA‑driven arm of aging, complementing nuclear‑centric approaches and providing a testable node where mito‑nuclear crosstalk converges on the innate immune axis.