A functional inflammasome activation assay differentiates patients with pathogenic NLRP3 mutations and symptomatic patients with low penetrance variants

- NLRP3 inflammasome products are increased after stimulation in CAPS patients.
- No increase was found in patients with low penetrance NLRP3 variants.
- IL-1β secretion in patients with CAPS mutations correlated with disease severity.
- This inflammasome activation assay points towards alternative pathophysiological mechanisms in low penetrance NLRP3 variants.

Cryopyrin-associated periodic syndromes (CAPS) are characterized by recurrent episodes of systemic inflammation caused by mutations in the NLRP3 gene. Besides confirmed pathogenic NLRP3 mutations, patients with CAPS-like symptoms frequently show low penetrance variants in NLRP3. The disease relevance of these variants is inconsistent. In this study, we investigated if an inflammasome activation assay differentiates between patients with confirmed pathogenic CAPS mutations, patients with low penetrance NLRP3 variants (V198M and Q703K) and healthy controls. The release of mature IL-1β, IL-18, and caspase-1 into cell culture supernatants after 4 h of inflammasome stimulation was significantly increased in patients with confirmed pathogenic CAPS mutations compared to low penetrance NLRP3 variants and controls. IL-1β secretion in CAPS patients correlated with disease severity. This inflammasome activation assay differentiates between autoinflammation patients with confirmed pathogenic CAPS mutations and patients with low penetrance NLRP3 variants, and points towards alternative pathophysiological mechanisms in low penetrance NLRP3 variants.