@article{3002786,
    title = "Enhanced activity of NLRP3 inflammasome in peripheral blood cells of patients with active rheumatoid arthritis",
    author = "Choulaki, C. and Papadaki, G. and Repa, A. and Kampouraki, E. and Kambas, K. and Ritis, K. and Bertsias, G. and Boumpas, D.T. and Sidiropoulos, P.",
    journal = "Arthritis Research and Therapy",
    year = "2015",
    volume = "17",
    number = "1",
    publisher = "BioMed Central Ltd.",
    doi = "10.1186/s13075-015-0775-2",
    keywords = "adenosine triphosphate;  caspase 3;  caspase 7;  caspase 8;  cryopyrin;  inflammasome;  interleukin 1beta;  interleukin 1beta converting enzyme;  lipopolysaccharide;  membrane protein;  polyinosinic polycytidylic acid;  protein ASC;  toll like receptor 2;  toll like receptor 3;  toll like receptor 4;  unclassified drug;  carrier protein;  cryopyrin;  inflammasome;  NLRP3 protein, human, adult;  Article;  blood cell;  cell level;  clinical article;  controlled study;  cytokine release;  disease activity;  drug targeting;  enzyme activity;  enzyme inhibition;  female;  human;  human cell;  immunoblotting;  male;  pathophysiology;  protein analysis;  protein expression;  protein function;  protein induction;  protein synthesis inhibition;  rheumatoid arthritis;  supernatant;  blood;  enzyme linked immunosorbent assay;  immunology;  leukocyte;  middle aged;  rheumatoid arthritis;  Western blotting, Arthritis, Rheumatoid;  Blotting, Western;  Carrier Proteins;  Enzyme-Linked Immunosorbent Assay;  Female;  Humans;  Inflammasomes;  Leukocytes;  Male;  Middle Aged;  NLR Family, Pyrin Domain-Containing 3 Protein",
    abstract = "Introduction: Interleukin-1β (IL-1β) is a major inflammatory cytokine, produced predominantly by innate immune cells through NLRP3-inflammasome activation. Both intrinsic and extrinsic danger signals may activate NLRP3. Genetic variations in NLRP3-inflammasome components have been reported to influence rheumatoid arthritis (RA) susceptibility and severity. We sought to assess the activity of NLRP3-inflammasome in patients with active RA compared to healthy individuals. Method: Intracellular protein expression of NLRP3, ASC, pro- and active caspase-1, pro- and active IL-1β was assessed by immunoblotting both at baseline and upon inflammasome activation. NLRP3 function (IL-1β secretion) was assessed upon priming of TLR2 (Pam(3)CysSK(4), TLR3 (poly(I:C)) or TLR4 (LPS) and ATP sequential treatment. We used caspase inhibitors (casp-1, 3/7 and 8) to assess their contribution to IL-1β maturation. All experiments were performed in whole blood cells. Results: Active RA patients (n = 11) expressed higher basal intracellular levels of NLRP3 (p < 0.008), ASC (p < 0.003), active caspase-1 (p < 0.02) and pro-IL-1β (p < 0.001). Upon priming with TLR4 (LPS) and ATP, RA-derived cell extracts (n = 7) displayed increased expression of NLRP3 (p < 0.01) and active caspase-1 (p < 0.001). Secreted IL-1β in culture supernatants from whole blood cells activated with TLR4 (LPS) or TLR3 agonist (poly(I:C)) plus ATP was higher in RA patients (n = 20) versus controls (n = 18) (p < 0.02 for both). Caspase-1 inhibition significantly reduced IL-1β secretion induced by all stimuli, whereas caspase-8 inhibition affected only TLR4 and TLR3 cell priming. Conclusion: Patients with active RA have increased expression of NLRP3 and NLRP3-mediated IL-1β secretion in whole blood cells upon stimulation via TLR3 and TLR4 but not TLR2. In these patients, IL-1β secretion seems to be predominately driven by caspase-1 and caspase-8. Targeting NLRP3 or downstream caspases may be of benefit in suppressing IL-1β production in RA. © 2015 Choulaki et al."
}