Sepsis is the leading cause of death in noncoronary intensive care units in the US. A pathognomonic feature of sepsis is severe tissue injury secondary to a profound release of host cell cytokines. Activation of tumor necrosis factor receptor associated factor (TRAF) proteins is crucial to septic inflammation as these proteins link cell surface signals to cytokine release. The mechanistic platform of this proposal resides on our discovery of a unique molecular model of innate immunity for cytokine release whereby a relatively new protein, Fbxo3, potently stimulates cytokine secretion from human inflammatory cells by destabilizing a sentinel TRAF inhibitor, Fbxl2 (Nature Immunology 14:470-9, 2013). Our pilot data indicate that Fbxo3 and TRAF proteins in circulation positively correlate with cytokine responses in septic subjects. We also identified a hypofunctional Fbxo3 human polymorphism. By targeting the prokaryotic-like Fbxo3 ApaG molecular signature, we developed a unique genus of small molecule inhibitors that lessen severity of cytokine-driven inflammation in murine models. Hence, in this application we will elucidate how Fbxo3 degrades Fbxl2 (Aim 1), test a novel chemical entity acting as a Fbxo3 ApaG inhibitor in septic models (Aim 2), and biologically characterize a Fbxo3->TRAF pathway and naturally occurring polymorphism in a prospective cohort study in subjects with sepsis (Aim 3). These studies will provide a new pathway of innate immunity that may identify subjects with altered immune responses during critical illness or provide a basis for therapeutic intervention targeting TRAF protein abundance.

Public Health Relevance

Sepsis is a major cause of morbidity and mortality in the US and evidence suggests that patients die from overwhelming systemic inflammation. This inflammation is caused from the release of proteins, called cytokines. We have discovered a new model of inflammation in subjects with sepsis. This discovery led us to develop a new family of small molecules that lessen severity of cytokine-driven inflammation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL097376-05A1
Application #
8694679
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Harabin, Andrea L
Project Start
2009-09-30
Project End
2018-04-30
Budget Start
2014-05-07
Budget End
2015-04-30
Support Year
5
Fiscal Year
2014
Total Cost
$412,976
Indirect Cost
$144,374
Name
University of Pittsburgh
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Liu, Yuan; Mallampalli, Rama K (2016) Small molecule therapeutics targeting F-box proteins in cancer. Semin Cancer Biol 36:105-19
Kitsios, Georgios D; Morris, Alison; McVerry, Bryan J (2016) Antibiotic de-escalation: observational causal inference and culture dependence. Intensive Care Med 42:1647-8
Zou, Chunbin; Synan, Matthew J; Li, Jin et al. (2016) LPS impairs oxygen utilization in epithelia by triggering degradation of the mitochondrial enzyme Alcat1. J Cell Sci 129:51-64
Krzysiak, Troy C; Chen, Bill B; Lear, Travis et al. (2016) Crystal structure and interaction studies of the human FBxo3 ApaG domain. FEBS J 283:2091-101
Agassandian, Marianna; Tedrow, John R; Sembrat, John et al. (2015) VCAM-1 is a TGF-β1 inducible gene upregulated in idiopathic pulmonary fibrosis. Cell Signal 27:2467-73
Han, SeungHye; Lear, Travis B; Jerome, Jacob A et al. (2015) Lipopolysaccharide Primes the NALP3 Inflammasome by Inhibiting Its Ubiquitination and Degradation Mediated by the SCFFBXL2 E3 Ligase. J Biol Chem 290:18124-33
Londino, James D; Gulick, Dexter; Isenberg, Jeffrey S et al. (2015) Cleavage of Signal Regulatory Protein α (SIRPα) Enhances Inflammatory Signaling. J Biol Chem 290:31113-25
Chen, Wei; Xiong, Sheng; Li, Jin et al. (2015) The ubiquitin E3 ligase SCF-FBXO24 recognizes deacetylated nucleoside diphosphate kinase A to enhance its degradation. Mol Cell Biol 35:1001-13
Liu, Yuan; Lear, Travis; Iannone, Olivia et al. (2015) The Proapoptotic F-box Protein Fbxl7 Regulates Mitochondrial Function by Mediating the Ubiquitylation and Proteasomal Degradation of Survivin. J Biol Chem 290:11843-52
Liu, Y; Lear, T; Zhao, Y et al. (2015) F-box protein Fbxl18 mediates polyubiquitylation and proteasomal degradation of the pro-apoptotic SCF subunit Fbxl7. Cell Death Dis 6:e1630

Showing the most recent 10 out of 50 publications