title: HMG-CoA reductase inhibition induces IL-1beta release through Rac1/PI3K/PKB-dependent caspase-1 activation.
abstract: Mevalonate kinase deficiency (MKD) is an autoinflammatory disorder characterized by recurring fever episodes and results from disturbed isoprenoid biosynthesis. Lipopolysaccharide-stimulated peripheral blood mononuclear cells from MKD patients secrete high levels of interleukin-1beta (IL-1beta) because of the presence of hyperactive caspase-1, and this has been proposed to be the primary cause of recurring inflammation. Here we show that inhibition of HMG-CoA reductase by simvastatin treatment, mimicking MKD, results in increased IL-1beta secretion in a Rac1/PI3K-dependent manner. Simvastatin treatment was found to activate protein kinase B (PKB)/c-akt, a primary effector of PI3K, and ectopic expression of constitutively active PKB was sufficient to induce IL-1beta release. The small GTPase Rac1 was activated by simvastatin, and this was required for both PKB activation and IL-1beta secretion. IL-1beta release is mediated by caspase-1, and simvastatin treatment resulted in increased caspase-1 activity in a Rac1/PI3K-dependent manner. These data suggest that, in MKD, dysregulated isoprenoid biosynthesis activates Rac1/PI3K/PKB, resulting in caspase-1 activation with increased IL-1beta release. Importantly, inhibition of Rac1 in peripheral blood mononuclear cells isolated from MKD patients resulted in a dramatic reduction in IL-1beta release. These data suggest that pharmacologic inhibition of Rac1 could provide a novel therapeutic strategy for treatment of MKD.
authors.affiliation: Department of General Pediatrics, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Loes M
authors.initials: LM
authors.lastname: Kuijk
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Beekman
authors.forename: Janet
authors.initials: J
authors.lastname: Koster
authors.forename: Hans R
authors.initials: HR
authors.lastname: Waterham
authors.forename: Joost
authors.initials: J
authors.lastname: Frenkel
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Coffer
mesh_terms: D001483:Base Sequence; D020170:Caspase 1 / Q000378:metabolism*; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D054078:Mevalonate Kinase Deficiency / Q000188:drug therapy / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D019821:Simvastatin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D017931:DNA Primers; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; C107953:RAC1 protein, human; D019821:Simvastatin; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D048051:p38 Mitogen-Activated Protein Kinases; D020170:Caspase 1; D020830:rac1 GTP-Binding Protein