Distinct Natural Killer Cell Signature in Still Disease: Insights From a Multinational Immunome Project Consortium...

Area of Science:

• Immunology
• Molecular Biology

Background:

• Still's disease (SD) is a rare systemic inflammatory disorder with unknown etiology.
• Natural killer (NK) cells are implicated in SD pathogenesis, but their exact role is unclear.

Purpose of the Study:

• To comprehensively characterize NK cell phenotype in SD and compare it to other systemic autoinflammatory diseases.
• To identify potential molecular regulators and therapeutic targets for SD-associated NK cell dysfunction.

Main Methods:

• NK cell phenotyping was performed on an international cohort of 121 patients with systemic autoinflammatory diseases (including 53 SD) and 32 healthy controls.
• Analysis included flow cytometry, assessment of apoptosis, cytokine responsiveness, and transcriptomic profiling (identifying miR-146a).

Main Results:

• SD patients exhibited a unique NK cell signature: reduced frequency, elevated Fas expression leading to increased apoptosis, and a hyperactivated yet exhausted phenotype with cytokine unresponsiveness.
• These NK cell abnormalities normalized during clinical remission and could be recapitulated by exposing healthy NK cells to inflammatory cytokines (IL-12, IL-15, IL-18).
• MicroRNA miR-146a was identified as a potential regulator of this NK cell dysfunction.

Conclusions:

• NK cell apoptosis, exhaustion, and cytokine unresponsiveness are defining immunological features of SD, differentiating it from other autoinflammatory diseases.
• This dysfunctional NK cell state may contribute to macrophage activation syndrome in SD.
• Inflammatory cytokines and miR-146a represent potential therapeutic targets for mitigating SD severity and preventing complications.