Nod2-Nodosome in a Cell-Free System: Implications in Pathogenesis and Drug Discovery for Blau Syndrome and Early-Onset Sarcoidosis.

Nucleotide-binding oligomerization domain-containing protein (Nod) 2 is an intracellular pattern recognition receptor, which recognizes muramyl dipeptide (N-Acetylmuramyl-L-Alanyl-D-Isoglutamine: MDP), a bacterial peptidoglycan component, and makes a NF-κB-activating complex called nodosome with adaptor protein RICK (RIP2/RIPK2). Nod2 mutants are associated with the autoinflammatory diseases, Blau syndrome (BS)/early-onset sarcoidosis (EOS). For drug discovery of BS/EOS, we tried to develop Nod2-nodosome in a cell-free system. FLAG-tagged RICK, biotinylated-Nod2, and BS/EOS-associated Nod2 mutants were synthesized, and proximity signals between FLAG-tagged and biotinylated proteins were detected by amplified luminescent proximity homogeneous assay (ALPHA). Upon incubation with MDP, the ALPHA signal of interaction between Nod2-WT and RICK was increased in a dose-dependent manner. The ALPHA signal of interaction between RICK and the BS/EOS-associated Nod2 mutants was more significantly increased than Nod2-WT. Notably, the ALPHA signal between Nod2-WT and RICK was increased upon incubation with MDP, but not when incubated with the same concentrations, L-alanine, D-isoglutamic acid, or the MDP-D-isoform. Thus, we successfully developed Nod2-nodosome in a cell-free system reflecting its function in vivo, and it can be useful for screening Nod2-nodosome-targeted therapeutic molecules for BS/EOS and granulomatous inflammatory diseases.

Anakinra improves sensory deafness in a Japanese patient with Muckle-Wells syndrome, possibly by inhibiting the cryopyrin inflammasome.

Muckle-Wells syndrome (MWS) is a dominantly inherited autoinflammatory syndrome. Patients with MWS have a mutation in CIAS1, the gene encoding cryopyrin, a component of the inflammasome that regulates the processing of interleukin-1beta (IL-1beta). In this report we describe an 8-year-old Japanese girl with MWS who had symptoms of periodic fever, urticarial rash, conjunctivitis, arthropathy, and sensory deafness. Laboratory analysis of the patient's serum showed abnormally high concentrations of C-reactive protein, serum amyloid A, and IL-1beta, and she had a heterozygous mutation in the CIAS1 gene, with C-to-T transversion at nucleotide position 778, encoding an arginine-to-tryptophan mutation at position 260 (R260W). Mononuclear cells (MNCs) isolated from the patient secreted large amounts of IL-1beta, without stimulation, and were highly sensitive to muramyldipeptide and lipopolysaccharide. After treatment with anakinra, laboratory results normalized, and clinical symptoms, including sensory deafness, disappeared, while MNCs appeared to remain activated. Thus, our case suggests that anakinra possibly affects the cryopyrin inflammasome and markedly improves the clinical and laboratory manifestations of MWS.