This FIRST award proposal investigates alterations in intracellular signal transduction as molecular mechanisms in sepsis and endotoxemia. Gram- negative sepsis is a leading cause of death worldwide. Treatment remains supportive. New and more effective therapies will require defining the pathogenesis of sepsis at molecular levels within the cell. The central hypothesis of this proposal is that specific intracellular signal transduction pathways are altered in macrophages upon repetitive endotoxin (LPS) stimulation. The activation states of these pathways ultimately protect or harm the host by exerting translational control of cytokine gene expression.
The specific aims of this proposal focus on distinct LPS-signaling pathways which diverge at inositol phosphate turnover. The pathway LPS chooses to take is proposed to determine the cellular LPS response. Using molecular biology tools applied to cell culture and animal models of LPS presensitization (tolerance), we propose to confirm or exclude the following: 1) Altered inositol phosphate signaling limits LPS responses; 2) LPS signaling is linked to translational control of cytokine gene expression through phosphorylation of specific cytoplasmic proteins; 3) Upon repetitive LPS stimulation, cell signaling shifts away from these pathways allowing the cell and host to regulate its response while confronting the bacterial threat. In a clinically relevant model of experimental sepsis, we propose to pharmacologically redirect cellular signaling and provide a protective survival benefit. Preliminary data suggest the central hypothesis is correct, and moreover, point to an unexpected link between LPS and insulin as extracellular ligands: co-utilization of signaling pathways coupling ligand binding with the translational control of cellular protein synthesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29GM053724-05
Application #
6019128
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Project Start
1996-03-01
Project End
2001-07-31
Budget Start
1999-08-01
Budget End
2000-07-31
Support Year
5
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Surgery
Type
Schools of Medicine
DUNS #
660735098
City
Worcester
State
MA
Country
United States
Zip Code
01655
Potter, M W; Shah, S A; Elbirt, K K et al. (2001) Endotoxin (LPS) stimulates 4E-BP1/PHAS-I phosphorylation in macrophages. J Surg Res 97:54-9
Vittimberga Jr, F J; Foley, D P; Perugini, R A et al. (1999) Endotoxin fails to stimulate inositol triphosphate production in macrophages. Int J Surg Investig 1:229-35
Vittimberga Jr, F J; McDade, T P; Perugini, R A et al. (1999) Sodium salicylate inhibits macrophage TNF-alpha production and alters MAPK activation. J Surg Res 84:143-9