Irène Lemelle

NLRP3-associated autoinflammatory disease is a heterogenous group of monogenic conditions caused by NLRP3 gain-of-function mutations. The poor functional characterization of most NLRP3 variants hinders diagnosis despite efficient anti-IL-1 treatments. Additionally, while NLRP3 is controlled by priming and activation signals, gain-of-functions have only been investigated in response to priming. Here, we characterize 34 NLRP3 variants in vitro, evaluating their activity upon induction, priming, and/or activation signals, and their sensitivity to four inhibitors. We highlight the functional diversity of the gain-of-function mutants and describe four groups based on the signals governing their activation, correlating partly with the symptom severity. We identify a new group of NLRP3 mutants responding to the activation signal without priming, associated with frequent misdiagnoses. Our results identify key NLRP3 residues controlling inflammasome activity and sensitivity to inhibitors, and antagonistic mechanisms with broader efficacy for therapeutic strategies. They provide new insights into NLRP3 activation, an explanatory mechanism for NLRP3-AID heterogeneity, and original tools for NLRP3-AID diagnosis and drug development.

A 20-year-old man presented with recurrent subdural haemorrhages on a background of progressive sensorineural hearing loss, juvenile idiopathic arthritis and intracranial hypertension of unknown cause. His mother had a similar previous history. They both had a persistently mildly elevated serum C reactive protein. Repeat lumbar punctures identified persistently elevated intracranial pressure and mild pleocytosis. A dural biopsy showed necrotising pachymeningitis with granulomatous vasculitis. The underlying cause in both patients was a cryopyrin-associated periodic syndrome. We discuss its varied phenotype and how clinicians need to be aware of this treatable genetic condition to facilitate early treatment and to prevent accumulation of disability.