Dual NLRP3 and IL-6R blockade restores NAD+–dependent mitochondrial fitness to reverse human immunosenescence

Hypothesis: Simultaneous inhibition of NLRP3 inflammasome assembly and IL-6 signaling synergistically reverses age‑associated immunosenescence by preserving cellular NAD+ pools, thereby enhancing SIRT3‑mediated mitochondrial antioxidant defenses and reducing mtDNA oxidative damage that fuels inflammasome priming.

Rationale: NLRP3 activation driven by cytosolic oxidized mtDNA triggers caspase‑1–dependent pyroptosis, releasing IL-1β and IL‑18 that amplify IL-6 production 1. Elevated IL-6 sustains chronic inflammation via STAT3‑driven Th17 differentiation and reinforces the senescence‑associated secretory phenotype (SASP) 2. This feed‑forward loop is potentiated by mitochondrial dysfunction, where ROS‑induced mtDNA damage further activates NLRP3 3, and IL-6 exposure reprograms immune cell metabolism to heighten NLRP3 responsiveness 4. Critically, both NLRP3 activation and IL-6/STAT3 signaling consume NAD+: inflammasome‑triggered PARP activation repairs mtDNA breaks, while STAT3 upregulates the NAD+‑glycohydrolase CD38, accelerating NAD+ depletion. NAD+ loss diminishes SIRT3 deacetylase activity, leading to hyperacetylated, ROS‑prone mitochondria and a vicious cycle of inflammasome priming.

We propose that combined NLRP3 inhibition (e.g., MCC950 binding the NACHT domain) and IL-6R blockade (e.g., tocilizumab) will preserve NAD+ by reducing PARP and CD38‑mediated consumption. Elevated NAD+ will reactivate SIRT3, which deacetylates and activates mitochondrial superoxide dismutase (SOD2) and glutathione peroxidase, lowering ROS and mtDNA damage. Consequently, inflammasome assembly declines, IL-6 production drops, and the SASP attenuates. This metabolic reset should restore hematopoietic stem cell (HSC) self‑renewal and increase naïve T‑cell output, measurable as improved colony‑forming unit (CFU) assays and higher CD45RA+CCR7+ T‑cell frequencies.

Testable predictions: (1) Ex vivo treatment of aged human peripheral blood mononuclear cells (PBMCs) or CD34+ HSCs with MCC950 plus anti‑IL‑6R will yield greater NAD+ levels (measured by LC‑MS) than either monotherapy. (2) SIRT3 activity (fluorometric deacetylase assay) and mitochondrial ROS (MitoSOX fluorescence) will improve only under dual treatment. (3) Senescence markers (p16^INK4a, SASP cytokines IL‑6, IL‑8) will show the most pronounced reduction with combined blockade. (4) Functional immune reconstitution—naïve T‑cell proportion and HSC CFU‑GEMM output—will be significantly higher in the dual‑condition versus single‑agent or vehicle controls.

Falsification: If dual NLRP3/IL-6R inhibition fails to raise NAD+ or improve mitochondrial ROS, SIRT3 activity, senescence markers, or functional immune readouts beyond the best single agent, the hypothesis is refuted, indicating that NAD+ preservation is not a critical convergent node of the NLRP3‑IL-6 loop in human immunosenescence.