title: An Essential Role for SHARPIN in the Regulation of Caspase 1 Activity in Sepsis.
abstract: Sepsis is burdened by high mortality due to uncontrolled inflammatory response to pathogens. Increased caspase 1 activation causing maturation of IL1β/18 remains a therapeutic challenge in sepsis. SHARPIN (shank-associated regulator of G-protein signaling homology domain-interacting protein), a component of the LUBAC (linear ubiquitin chain-assembly complex), regulates inflammation, with unknown effects on caspase 1 activation. Mice lacking Casp1, Casp11, or both in a Sharpin-deficient background were generated, exposed to lipopolysaccharide-induced endotoxemia, and injected with caspase 1 inhibitor. We monitored survival, Il1β/18, and caspase 1/11 levels in plasma and organs and deciphered mechanisms of SHARPIN-dependent caspase 1 inhibition. A correlation between LUBAC and active caspase 1 was found in blood mononuclear cells from septic patients. SHARPIN bound caspase 1 and disrupted p20/p10 dimer formation, the last step of caspase 1 processing, thereby inhibiting enzyme activation and maturation of IL1β/18 in a LUBAC-independent manner. In septic patients, LUBAC-independent decline in SHARPIN correlated with enhancement of active caspase 1 in circulating mononuclear cells. Septic Sharpin-deficient mice displayed enrichment in mature Il1β/18 and active caspase 1, and shortened survival. Inhibition of caspase 1 reduced levels of Il1β/18 and splenic cell death, and prolonged survival in septic Sharpin-deficient mice. Our findings identify SHARPIN as a potent in vivo caspase 1 inhibitor and propose the caspase 1-SHARPIN interaction as a target in sepsis.
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany; National Institute for Chemical-Pharmaceutical Research and Development, Bucharest, Romania.
authors.forename: Madalina-Viviana
authors.initials: MV
authors.lastname: Nastase
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Jinyang
authors.initials: J
authors.lastname: Zeng-Brouwers
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Frey
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Louise Tzung-Harn
authors.initials: LT
authors.lastname: Hsieh
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Chiara
authors.initials: C
authors.lastname: Poluzzi
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Janet
authors.initials: J
authors.lastname: Beckmann
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Schroeder
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeilschifter
authors.affiliation: Institute of Biochemistry II, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Jaime
authors.initials: J
authors.lastname: Lopez-Mosqueda
authors.affiliation: Department of Anaesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Mersmann
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Ikeda
authors.affiliation: Department of Pathology, Anatomy and Cell Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Renato V
authors.initials: RV
authors.lastname: Iozzo
authors.affiliation: Institute of Biochemistry II, Goethe Universität, Frankfurt am Main, Germany.
authors.forename: Ivan
authors.initials: I
authors.lastname: Dikic
authors.affiliation: Pharmacenter Frankfurt/ZAFES, Institute of General Pharmacology and Toxicology, Goethe Universität, Frankfurt am Main, Germany. Electronic address: schaefer@med.uni-frankfurt.de.
authors.forename: Liliana
authors.initials: L
authors.lastname: Schaefer
mesh_terms: D000818:Animals; D020170:Caspase 1 / Q000172:deficiency / Q000378:metabolism*; D061945:Caspase Inhibitors / Q000494:pharmacology; D020169:Caspases / Q000172:deficiency / Q000378:metabolism; D053471:Caspases, Initiator; D002478:Cells, Cultured; D003872:Dermatitis / Q000201:enzymology; D015536:Down-Regulation / Q000502:physiology; D019446:Endotoxemia / Q000139:chemically induced; D055785:Gene Knockdown Techniques; D020382:Interleukin-18 / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000201:enzymology; D008070:Lipopolysaccharides / Q000633:toxicity; D008168:Lung / Q000201:enzymology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000502:physiology*; D010641:Phenotype; D012475:Salmonella; D018805:Sepsis / Q000201:enzymology*; D014162:Transfection
chemical_list: D061945:Caspase Inhibitors; D020382:Interleukin-18; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; C425287:sharpin; C101136:Casp4 protein, mouse; D020169:Caspases; D053471:Caspases, Initiator; D020170:Caspase 1