title: Dysregulated production of interleukin-1β upon activation of the NLRP3 inflammasome in patients with familial Mediterranean fever.
abstract: Familial Mediterranean fever (FMF) is caused by mutations in pyrin, a protein expressed in innate immune cells that interacts with caspase-1 and other inflammasome components to regulate interleukin (IL)-1β maturation. Since NLRP3 inflammasome represents major source of IL-1β, we studied its protein expression and function in FMF. We isolated peripheral white blood cells (WBCs) from 20 symptoms-free FMF patients and 21 healthy individuals. Intracellular protein expression of NLRP3, caspase-1, IL-1β at baseline and after LPS/ATP sequential treatment for NLRP3 activation was assessed by immunoblotting. Secreted IL-1β was quantified by ELISA. THP-1 cells were transfected with wild-type or mutant pyrin and IL-1β secretion was measured. FMF WBCs exhibited lower NLRP3 and active caspase-1 protein expression compared to healthy individuals, and LPS/ATP treatment resulted in significantly lower intracellular IL-1β levels in FMF patients. Likewise, LPS/ATP induced caspase-1-dependent IL-1β release at significantly lower amounts in the FMF group (1182±192 versus 2134±245pg/mL in controls, p=0.004). Consistently, THP-1 cells transfected with FMF-associated M694V mutant pyrin displayed lower LPS/ATP-induced IL-1β compared with wild-type pyrin-transfected cells. FMF WBCs demonstrate reduced NLRP3-mediated IL-1β production. Additional studies are needed to define whether this finding represents a compensatory mechanism to control inflammation or is directly linked to disease pathogenesis.
authors.affiliation: Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece; Division of Infections and Immunity, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece. Electronic address: arrepa2002@yahoo.gr.
authors.forename: Argyro
authors.initials: A
authors.lastname: Repa
authors.affiliation: Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece; Division of Infections and Immunity, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece. Electronic address: gbert@med.uoc.gr.
authors.forename: George K
authors.initials: GK
authors.lastname: Bertsias
authors.affiliation: Laboratory of Molecular Medicine and Human Genetics, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Petraki
authors.affiliation: Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece; Division of Infections and Immunity, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece. Electronic address: choulaki@med.uoc.gr.
authors.forename: Christianna
authors.initials: C
authors.lastname: Choulaki
authors.affiliation: Division of Nano-biotechnology, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece. Electronic address: dvassou@imbb.forth.gr.
authors.forename: Despoina
authors.initials: D
authors.lastname: Vassou
authors.affiliation: Laboratory of Molecular Hematology, Democritus University of Thrace, 68100 Alexandroupolis, Greece. Electronic address: kkampas@hotmail.com.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Kambas
authors.affiliation: Division of Infections and Immunity, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece; Third Department of Medicine, Rheumatology-Clinical Immunology Unit, "Sotiria" General Hospital of Thoracic Diseases, 152 Mesogion Avenue, 11527 Athens, Greece; Biomedical Research Foundation of the Academy of Athens, 4 Soranou Ephessiou, 115 27 Athens, Greece. Electronic address: boumpasd@med.uoc.gr.
authors.forename: Dimitrios T
authors.initials: DT
authors.lastname: Boumpas
authors.affiliation: Laboratory of Molecular Medicine and Human Genetics, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece. Electronic address: goulielmos@med.uoc.gr.
authors.forename: George
authors.initials: G
authors.lastname: Goulielmos
authors.affiliation: Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine, University of Crete, 71003 Iraklion, Greece; Division of Infections and Immunity, Institute of Molecular Biology and Biotechnology-FORTH, Nikolaou Plastira 100, 70013 Iraklion, Greece. Electronic address: sidiropp@med.uoc.gr.
authors.forename: Prodromos
authors.initials: P
authors.lastname: Sidiropoulos
mesh_terms: D000328:Adult; D002352:Carrier Proteins / Q000502:physiology*; D020170:Caspase 1 / Q000378:metabolism; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics; D010505:Familial Mediterranean Fever / Q000276:immunology*; D005260:Female; D006801:Humans; D058847:Inflammasomes / Q000502:physiology*; D053583:Interleukin-1beta / Q000096:biosynthesis*; D008297:Male; D009154:Mutation; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D000071198:Pyrin
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; C000604192:MEFV protein, human; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D000071198:Pyrin; D020170:Caspase 1
keywords: Autoinflammatory disorders; Cytokine; Inflammasome; Innate immunity