Jason Todd Primm

Document Type:

MasterŐs Thesis

Name:

Jason Todd Primm

Email Address:

primm@utmem.edu

Title:

Differential Stimulation of Monocytes to Secrete Secretory Leukocyte Protease Inhibitor by Lipopolysaccharide of Periodontal Pathogens

Degree:

Master of Dental Science

Major:

Periodontology

Program:

 

Track, if Integrated Program in Biomedical Sciences:

Research Advisor:

Jegdish Babu Ph.D.

Advisor's Email:

jbabu@utmem.edu

Committee Members:

Predeep C. Adatrow, D.D.S.

 

Sidney H. Stein, D.D.S., Ph.D.

 

 Edwin L. Thomas, Ph.D.

 

 David A. Tipton, D.D.S., Ph.D.

Keywords:

LPS, Periodontitis, SLPI

Availability:

World-Wide Web Access

 

 

Abstract

               Lipopolysaccharide (LPS), or endotoxin, is the major component of the outer surface of gram-negative bacteria. LPS is a potent activator of cells of the immune and 
inflammatory systems, including macrophages, monocytes, and endothelial cells, and contributes to systemic changes known as septic shock. Each LPS molecule has three 
regions: oligosaccharide, core, and lipid A. Oligosaccharide is exposed on the cell surface, and lipid A anchors LPS in the outer membrane. Recent studies from our lab demonstrated that 
LPS of periodontal pathogens suppresses neutrophil's ability to secrete super oxide ions and also shown it to interfere with neutrophil chemotaxis. These factors are believed to aid the 
pathogens to remain "stealthy" and avoid killing by the mononuclear phagocyte cells. Secretory Leukocyte Protease Inhibitor (SLPI) is a single-chain serine protease inhibitor secreted from 
secretary and inflammatory cells that protects tissue from damage caused by the inflammatory response. The present study examined the interaction of LPS prepared from periodontal
 pathogens with monocytes to stimulate them to secrete SLPI. The hypothesis of this study is that (1) LPS molecules of more pathogenic periodontal pathogens are better inducer of monocots
 to secrete SLPI, and (2) Secreted SLPI in turn inhibits the production of inflammatory cytokines produced by monocytes in response to LPS. The limited stimulation of monotypic cells to 
secrete super oxide ions as shown previously along with the proposed hypothesis that pathogenic organisms produces more SLPI to suppress the inflammatory cytokines may aid the pathogens 
to remain undetected by mononuclear phagocytes.
 
               The LPS from three different periodontal pathogens, Porphyromonas gingivalis, Prevotella denticola, and Fusobacterium nucleatum were isolated for this study under identical 
conditions. Cultured human monocytic cells were incubated with LPS and the amounts of SLPI secreted were measured. Monocytic cells were also incubated with endogenous SLPI along 
with LPS of the selected periodontal pathogens and the secretion of the cytokines IL-1β and TNF-α was measured by ELISA.
 
               The results demonstrated that LPS of periodontal pathogens differ in their ability to stimulate inflammatory cytokines. Pathogenic strains appear to induce secretion of greater amounts 
of cytokines than the less pathogenic organisms. Pathogenic organisms tested also showed to induce the cultured THP-1 cells to secrete SLPI. In the presence of exogenous SLPI, the amounts 
of inflammatory cytokines secreted by THP cells when stimulated with LPS appeared to be diminished.
 

The long-term objective is to understand the mechanisms, by which the periodontal pathogens escape detection by human defensive cells, colonize the gingival tissue and cause severe periodontitis. Understanding the evasive mechanisms by which pathogenic microorganisms escape detection or stimulate the host cells to secrete proteins, such as SLPI, which suppresses production of inflammatory cytokines, may aid the pathogenic organisms to survive in the oral cavity and continue their pathogenic effects.

Attached File(s)

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Revised 20 June 2009