In up to 80% of patients with symptoms of an autoinflammatory syndrome (periodic fever syndrome) a molecular diagnosis is currently not possible. Procaspase-1 (aka IL-1 converting enzyme, ICE) is a component of the CIAS1/NALP3 ‘inflammasome’ and plays critical roles in releasing the proinflammatory cytokine IL-1b. and regulating the NFkB-activating RIP-2 pathway. Sequencing of the procaspase-1 coding region from 200 patients with undiagnosed autoinflammatory syndromes revealed mutations in 8 patients, 7 of whom were heterozygous. The autoinflammatory syndrome associated with these mutations has tentatively been termed ‘ICE Fever’. X-ray crystallography and functional studies revealed that the resulting amino acid changes destabilize interactions within the interface of the mature caspase-1 tetramer and thus reduce proteolytic activity and IL-1b release. One consequence is an overactivity of the pro-inflammatory RIP-2 pathway due to diminished proteolytic inactivation of RIP-2 by caspase-1, potentially leading to autoinflammation. We propose to establish a mouse model for ‘ICE Fever’ by generating transgenic mice in which a single amino acid substitution in the active center has abolished the proteolytic activity of procaspase-1. For transgenesis, a novel ‘switch dual color’ vector will be used that allows to reproduce the wild type, heterozygous and homozygous states. Mice will be monitored in detail for the development of signs, symptoms and laboratory abnormalities suggestive of autoinflammation. Monosodium urate crystals, which are known to activate the NALP3 inflammasome, and the murine air pouch model of inflammation will be used to test for a possible exaggerated innate immune response. This will be the first mouse model for an inflammasome-associated autoinflammatory syndrome. It may afford new insights into the pathogenesis and treatment of ‘ICE Fever’ and into the roles of procaspase-1 and the RIP-2 pathway in inflammation in gener