Previous Article | Next Article ![]()
Infect. Immun., Aug 1997, 3248-3254, Vol 65, No. 8
FA Roberts, GJ Richardson and SM Michalek
The mononuclear phagocyte plays an important role in the regulation of
microbe-induced inflammation, in part through its ability to secrete
mediators, particularly cytokines, in response to microorganisms and their
products. To evaluate the effects of the microbial flora associated with
chronic adult periodontitis on cytokine induction, lipopolysaccharide (LPS)
from the periodontopathogen Porphyromonas gingivalis was used to stimulate
naive and phorbol ester-primed U937 monocytic cells, as well as elutriated
human peripheral blood monocytes. We assessed the effect of this LPS, in
comparison to that of LPS from Escherichia coli, on cell proliferation,
cytokine induction, and surface expression of the LPS receptor CD14. P.
gingivalis LPS stimulated proliferation of U937 cells at concentrations of
greater than 1 ng/ml, while E. coli LPS inhibited proliferation. Phorbol
myristic acid (PMA)-treated U937 cells and elutriated monocytes responded
to E. coli LPS activation by producing tumor necrosis factor alpha
(TNF-alpha) mRNA and protein; however, P. gingivalis LPS induced greater
numbers of TNF-alpha mRNA-positive cells and higher (P < 0.05) levels of
protein than did E. coli LPS. Both cell types expressed interleukin-1 beta
(IL-1beta) mRNA and protein in response to either LPS treatment. Compared
with E. coli LPS, P. gingivalis LPS induced significantly (P < 0.05)
higher numbers of IL-1 mRNA-positive U937 cells and elutriated monocytes,
as well as production of significantly more (P < 0.05) IL-1 protein by
the monocytes. The PMA-treated U937 cells and the monocytes produced high
levels of IL-1 receptor antagonist mRNA and protein which were only
marginally affected by the LPS preparations. While E. coli LPS induced
expression of CD 14 on the surface of PMA-primed U937 cells and monocytes,
P. gingivalis LPS exhibited a significantly (P < 0.05) greater ability
to enhance receptor levels. Our results indicate that P. gingivalis LPS can
activate the mononuclear phagocyte for proliferation, cytokine production,
and CD14 expression, providing evidence for the potential of this bacterial
component to act as a critical regulatory factor in the chronic
inflammatory response associated with periodontitis.
Copyright © 1997, American Society for Microbiology
Effects of Porphyromonas gingivalis and Escherichia coli lipopolysaccharides on mononuclear phagocytes
Department of Periodontics, School of Dentistry, The University of Alabama at Birmingham, 35294, USA.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|