Related Experiment Videos
Porphyromonas gingivalis lipopolysaccharide stimulation of human monocytes: dependence on serum and CD14 receptor
L Shapira1, S Takashiba, S Amar
1Department of Periodontology, Eastman Dental Center, Rochester, New York.
Abstract:
The purpose of this study was to investigate factors influencing the ability of lipopolysaccharide (LPS) derived from Porphyromonas gingivalis to elicit secretion of tumor necrosis factor-alpha (TNF alpha) from human monocytes (adherent mononuclear cells). The results indicate that P. gingivalis LPS stimulation of TNF alpha from monocytes is comparable to LPS from Escherichia coli. Both LPS, although structurally different, increased TNF alpha secretion in a dose-dependent manner. In serum-free conditions, TNF alpha secretion was relatively low, but it dramatically increased at human serum concentrations as low as 1%. Maximal secretion was observed in the presence of 10% serum, with a slight decrease at higher serum concentrations. The CD14 molecule is a putative monocyte LPS receptor. When cells were pre-incubated with a blocking monoclonal antibody (My4) to CD14, TNF alpha-mRNA accumulation and TNF alpha secretion were reduced to control levels at LPS concentrations of up to 10 ng/ml. At higher LPS concentrations, the blocking effect was only partial, in spite of 50-fold excess antibody concentration. The blocking effect was observed only in the presence of serum. The effect of the CD14 antibody was dose-dependent with saturation at 2.5 micrograms/ml. The results suggest that CD14 is one of the major receptors for P. gingivalis LPS but highlight the necessity to investigate other cell-surface receptors mediating P. gingivalis-LPS interactions. These interactions are believed to be important in the pathogenesis of periodontal destruction.
Insights
Porphyromonas gingivalis lipopolysaccharide (LPS) triggers tumor necrosis factor-alpha (TNF alpha) secretion from human monocytes, similar to E. coli LPS. CD14 acts as a key receptor, especially with serum present, but other receptors are also involved.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Porphyromonas gingivalis is implicated in periodontal disease pathogenesis.
- Lipopolysaccharide (LPS) is a key bacterial component that can activate immune responses.
- Tumor necrosis factor-alpha (TNF alpha) is a critical inflammatory cytokine.
Purpose of the Study:
- To investigate factors influencing TNF alpha secretion from human monocytes stimulated by P. gingivalis LPS.
- To compare the effects of P. gingivalis LPS with Escherichia coli LPS on monocyte TNF alpha secretion.
- To explore the role of the CD14 molecule in mediating P. gingivalis LPS-induced TNF alpha release.
Main Methods:
- Human monocytes were stimulated with P. gingivalis LPS and E. coli LPS.
- TNF alpha secretion was measured under varying serum concentrations.
- Monocytes were pre-incubated with a CD14 blocking antibody (My4) before LPS stimulation.
- TNF alpha mRNA accumulation and protein secretion were quantified.
Main Results:
- P. gingivalis LPS induced TNF alpha secretion comparable to E. coli LPS in a dose-dependent manner.
- Serum significantly enhanced LPS-induced TNF alpha secretion, with optimal levels at 10% serum.
- CD14 blocking antibody reduced TNF alpha secretion and mRNA accumulation, particularly at lower LPS concentrations and in the presence of serum.
- The CD14 blocking effect was dose-dependent and saturated at 2.5 µg/ml.
Conclusions:
- CD14 is a significant receptor for P. gingivalis LPS on human monocytes.
- Serum enhances the interaction between P. gingivalis LPS and monocytes.
- Additional cell-surface receptors likely mediate P. gingivalis LPS interactions, warranting further investigation.
- Understanding these interactions is crucial for elucidating the pathogenesis of periodontal destruction.