Hypothesis

Combined pharmacological inhibition of the NLRP3 inflammasome and blockade of IL-6 signaling will synergistically restore thymic output and macrophage proinflammatory capacity in aged mice, exceeding the effects of either monotherapy.

Mechanistic Rationale

NLRP3 activation in aged thymic stromal cells generates IL-1β, which induces SOCS3 expression in resident macrophages. SOCS3 then attenuates IL-6 trans‑signaling, creating a feedback loop that locks macrophages into a low‑TNF‑α/IL-6 state despite high inflammasome activity. Blocking NLRP3 reduces IL-1β‑driven SOCS3 up‑regulation, while IL-6R blockade prevents the residual immunosuppressive signal, allowing macrophages to regain LPS‑induced TNF‑α production. Simultaneously, reduced inflammasome activity lessens caspase‑1‑mediated damage to thymic epithelium, preserving naive T‑cell niches.

Experimental Design

• Animals: 20‑month‑old C57BL/6 mice (n=10 per group).
• Groups: (1) Vehicle control, (2) MCC950 (NLRP3 inhibitor, 10 mg/kg i.p. q.d.), (3) Tocilizumab‑equivalent anti‑IL‑6R antibody (10 mg/kg i.p. twice weekly), (4) Combination of MCC950 + anti‑IL‑6R.
• Duration: 4 weeks.
• Readouts:
  • Thymic cellularity and CD4⁺CD8⁺ double‑positive flow cytometry.
  • Peripheral naive CD62L⁺CD44⁻ T‑cell frequency.
  • Ex vivo bone‑marrow‑derived macrophages stimulated with LPS (100 ng/ml) for 6 h; measure TNF-α and IL‑6 by ELISA.
  • Western blot for phosphorylated STAT3 and SOCS3 in macrophages.
  • Serum IL-1β and cholesterol levels as inflammasome activity markers.

Expected Outcomes

• Monotherapy groups will show moderate improvements: MCC950 ↑ thymic cellularity (~30 %) but limited macrophage TNF‑α; anti‑IL‑6R ↑ macrophage TNF‑α (~25 %) with modest thymic effect.
• Combination group is predicted to exhibit additive to synergistic gains: thymic cellularity ↑ >55 %, naive T‑cell pool ↑ >50 %, and macrophage TNF‑α production restored to ≥90 % of young‑mouse levels.
• SOCS3 protein should be lowest in the combination group, confirming disruption of the IL‑1β‑SOCS3‑IL‑6 feedback loop.

Falsifiability

If the combination does not produce a statistically significant greater improvement over the best single treatment (p > 0.05, ANOVA with post‑hoc Tukey), the hypothesis is refuted. Conversely, a significant synergistic effect supports the proposed mechanistic link between NLRP3‑driven IL‑1β, SOCS3‑mediated IL‑6 resistance, and immunosenescence.