ABSTRACT: NLRP3 nucleates the inflammasome, a protein complex responsible for cleavage of prointerleukin-1beta (IL-1beta) to its active form. Mutations in the NLRP3 gene cause the autoinflammatory disease spectrum cryopyrin-associated periodic syndromes (CAPS). The central role of IL-1beta in CAPS is supported by the response to IL-1-targeted therapy. We developed two Nlrp3 mutant knockin mouse strains to model CAPS to examine the role of other inflammatory mediators and adaptive immune responses in an innate immune-driven disease. These mice had systemic inflammation and poor growth, similar to some human CAPS patients, and demonstrated early mortality, primarily mediated by myeloid cells. Mating these mutant mice to various gene mutant backgrounds showed that the mouse disease phenotype required an intact inflammasome, was only partially dependent on IL-1beta, and was independent of T cells. These data suggest that CAPS are true inflammasome-mediated diseases and provide insight for more common inflammatory disorders.
Immunity 07/2009; 30(6):875-87. · 21.64 Impact Factor
ABSTRACT: Inflammation under sterile conditions is a key event in autoimmunity and following trauma. Hyaluronan, a glycosaminoglycan released from the extracellular matrix after injury, acts as an endogenous signal of trauma and can trigger chemokine release in injured tissue. Here, we investigated whether NLRP3/cryopyrin, a component of the inflammasome, participates in the inflammatory response to injury or the cytokine response to hyaluronan. Mice with a targeted deletion in cryopyrin showed a normal increase in Cxcl2 in response to sterile injuries but had decreased inflammation and release of interleukin-1beta (IL-1beta). Similarly, the addition of hyaluronan to macrophages derived from cryopyrin-deficient mice increased release of Cxcl2 but did not increase IL-1beta release. To define the mechanism of hyaluronan-mediated activation of cryopyrin, elements of the hyaluronan recognition process were studied in detail. IL-1beta release was inhibited in peritoneal macrophages derived from CD44-deficient mice, in an MH-S macrophage cell line treated with antibodies to CD44, or by inhibitors of lysosome function. The requirement for CD44 binding and hyaluronan internalization could be bypassed by intracellular administration of hyaluronan oligosaccharides (10-18-mer) in lipopolysaccharide-primed macrophages. Therefore, the action of CD44 and subsequent hyaluronan catabolism trigger the intracellular cryopyrin --> IL-1beta pathway. These findings support the hypothesis that hyaluronan works through IL-1beta and the cryopyrin system to signal sterile inflammation.
Journal of Biological Chemistry 04/2009; 284(19):12762-71. · 4.77 Impact Factor
ABSTRACT: Familial cold autoinflammatory syndrome (FCAS) is characterized by rash, fever, and arthralgia in response to cold exposure. CIAS1, the gene that codes for cryopyrin, is mutated in FCAS. Treatment with anakinra (IL-1 receptor antagonist) prevents symptoms, indicating a crucial role for IL-1 in this disease.
To study cytokine responses to cold exposure in monocytes from subjects with FCAS.
Adherence-enriched monocytes were incubated at 32 degrees C or 37 degrees C. Transcription and release of IL-1beta, IL-6, and TNF-alpha were monitored by quantitative PCR and ELISA.
The FCAS monocytes but not control cells responded to 4 h incubation at 32 degrees C with significant secretion of IL-1beta. At 16 h, IL-1beta, IL-6, and TNF-alpha were all significantly elevated in FCAS monocytes at 32 degrees C. Increased cytokine transcription was observed in all monocytes at 4 hours, but at 16 hours it was only seen in FCAS monocytes incubated at 32 degrees C. Incubation at 32 degrees C for as little as 1 hour sufficed to induce measurable IL-1beta release. Caspase-1 inhibitors prevented the cold-induced IL-1beta release, whereas a purinergic antagonist did not. Anakinra had no effect on the early IL-1beta release but significantly reduced the late-phase transcription and release of all cytokines.
FCAS monocytes respond to mild hypothermia with IL-1beta release, which in turn induces autocrine transcription and secretion of IL-6 and TNF-alpha as well as stimulation of further IL-1beta production.
These results confirm the central role of IL-1beta in FCAS and support the use of IL-1 targeted therapy in these patients.
Journal of Allergy and Clinical Immunology 05/2007; 119(4):991-6. · 11.00 Impact Factor