The proposed studies are focused on detailed characterization of the molecular mechanism of CD14-dependent activation of immunocompetent cells during sepsis and septic shock. CD14 is a membrane GPI-anchored """"""""pattern recognition receptor"""""""" that is found to be associated with sphingolipid-rich microdomains in monocytes and macrophages. Although CD14 lack of a transmembrane domain, it is capable of recognizing a variety of gram-negative and gram-positive bacterial components including but, perhaps, not limited, lipopolysaccharide (LPS), peptidoglycan, lipoarabinomannan (LAM), and lipoproteins. This CD14-mediated activation of monocytes/macrophages by bacterial products results in a potent host cytokine response. Evidently, specific binding of microbial constituents to CD14 initiates a signal transduction cascade in the target cells. The potential role of CD14 in the pathophysiologic sequelae of bacterial sepsis is supported by studies on CD14 knockout mice that strongly indicate the resistance of these mice to otherwise lethal LPS-mediated shock and to the effects of severe bacterial infection. However, the mechanism of CD14-dependent activation of phagocytes remains poor understood. A number of Toll-like receptors (TLRs), that are homologues to the Drosophila Toll receptor, have recently been characterized. It was shown that TLRs mediate signaling by LPS and other microbial constituents in mammalian cells. The PI and his colleagues have demonstrated a direct association between Toll-like receptors and LPS in the cell membrane. To define the functional role of CD14 and TLRs in signaling and activation of myeloid cells, it is proposed to use a combination of biochemical (delineation of CD14-TLR associated kinase cascade) and genetic approaches (selection of mutant macrophage cells and correction of their specific defects with a cDNA library). The relationship between CD14, scr kinases, G proteins and the TLRs in mechanism of signaling will be defined, as will cellular location. These studies will help to define how host invasion by microbes leads to septic shock and may provide novel targets for the design of therapeutic interventions against the life-threatening conditions associated with bacterial sepsis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM063244-02
Application #
6387315
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Program Officer
Somers, Scott D
Project Start
2000-09-01
Project End
2004-08-31
Budget Start
2001-09-01
Budget End
2002-08-31
Support Year
2
Fiscal Year
2001
Total Cost
$371,907
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
660735098
City
Worcester
State
MA
Country
United States
Zip Code
01655
van Lint, Allison L; Murawski, Matthew R; Goodbody, Rory E et al. (2010) Herpes simplex virus immediate-early ICP0 protein inhibits Toll-like receptor 2-dependent inflammatory responses and NF-kappaB signaling. J Virol 84:10802-11
Kurt-Jones, Evelyn A; Chan, Melvin; Zhou, Shenghua et al. (2004) Herpes simplex virus 1 interaction with Toll-like receptor 2 contributes to lethal encephalitis. Proc Natl Acad Sci U S A 101:1315-20
Solomon, Keith R; Sharma, Parul; Chan, Melvin et al. (2004) CD109 represents a novel branch of the alpha2-macroglobulin/complement gene family. Gene 327:171-83
Fitzgerald, Katherine A; Rowe, Daniel C; Barnes, Betsy J et al. (2003) LPS-TLR4 signaling to IRF-3/7 and NF-kappaB involves the toll adapters TRAM and TRIF. J Exp Med 198:1043-55
Sandor, Frantisek; Latz, Eicke; Re, Fabio et al. (2003) Importance of extra- and intracellular domains of TLR1 and TLR2 in NFkappa B signaling. J Cell Biol 162:1099-110
Malley, Richard; Henneke, Philipp; Morse, Sarah C et al. (2003) Recognition of pneumolysin by Toll-like receptor 4 confers resistance to pneumococcal infection. Proc Natl Acad Sci U S A 100:1966-71
Latz, Eicke; Visintin, Alberto; Lien, Egil et al. (2003) The LPS receptor generates inflammatory signals from the cell surface. J Endotoxin Res 9:375-80
Espevik, Terje; Latz, Eicke; Lien, Egil et al. (2003) Cell distributions and functions of Toll-like receptor 4 studied by fluorescent gene constructs. Scand J Infect Dis 35:660-4
Visintin, Alberto; Latz, Eicke; Monks, Brian G et al. (2003) Lysines 128 and 132 enable lipopolysaccharide binding to MD-2, leading to Toll-like receptor-4 aggregation and signal transduction. J Biol Chem 278:48313-20
Compton, Teresa; Kurt-Jones, Evelyn A; Boehme, Karl W et al. (2003) Human cytomegalovirus activates inflammatory cytokine responses via CD14 and Toll-like receptor 2. J Virol 77:4588-96

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