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Prostaglandin E2 secretion, cell maturation, and CD14 expression by monocyte-derived macrophages from localized
L Shapira1, W A Soskolne, T E Van Dyke
1Department of Periodontology, Hebrew University-Hadassah Faculty of Dental Medicine, Jerusalem, Israel.
Abstract:
Previous studies from our laboratory have demonstrated that freshly isolated peripheral blood monocytes from localized juvenile periodontitis (LJP) patients secrete more prostaglandin E2 (PGE2) after stimulation by lipopolysaccharide (LPS) than do monocytes from healthy subjects. However, it is not clear if the altered function of LJP monocytes is intrinsic to the cells or is induced by the persistent infection of the periodontium. The present study was designed to compare PGE2 secretion by freshly-isolated peripheral blood monocytes (FIM) from LJP and control subjects to in vitro monocyte-derived macrophages (MDM) from the same subjects. We also examined monocyte maturation into macrophage-like cells and the cell-surface expression of the LPS, receptor, CD14 during the culture period. FIM from LJP patients and controls were stimulated by different concentrations of LPS (O to 30 micrograms/ml) for 24 hours. These experiments were performed immediately after cell separation and after 10 days in culture, which allowed differentiation of monocytes into MDM. PGE2 levels in the culture media were determined using a radioimmunoassay. Cell surface expression of CD71, a cell maturation marker, and CD14 were assayed by cell-ELISA in relation to beta-2-microglobulin. LPS-stimulated FIM from LJP patients secreted 3 to 4 times more PGE2 than control FIM at all LPS concentrations tested. After 10 days in culture, the LJP MDM secretion of PGE2 reduced to control MDM level of PGE2 secretion. These levels of PGE2 secretion were comparable to PGE2 secretion from FIM of controls. Cell maturation, as verified by CD71 expression, was found not to differ between the groups. However, the expression of CD14 by LJP FIM was much lower than on control FIM (approximately equal to 50%). After 5 or 10 days in culture, MDM from both control and LJP subjects expressed comparable amounts of CD14. The results suggest that in vitro conditions reverse the hypersensitivity of LJP monocytes to LPS into control levels and CD14 expression is not correlated to the hyper-responsiveness of the cells to LPS.
Insights
Monocytes from localized juvenile periodontitis (LJP) patients show increased prostaglandin E2 (PGE2) secretion. In vitro culture normalizes this hyper-responsiveness, suggesting it
Area of Science:
- Immunology
- Periodontology
- Cell Biology
Background:
- Peripheral blood monocytes from localized juvenile periodontitis (LJP) patients exhibit heightened prostaglandin E2 (PGE2) secretion upon lipopolysaccharide (LPS) stimulation.
- It remains unclear whether this altered monocyte function is an intrinsic cellular trait or a consequence of chronic periodontal infection.
Purpose of the Study:
- To compare PGE2 secretion in freshly isolated monocytes (FIM) and in vitro-differentiated macrophages (MDM) from LJP patients and healthy controls.
- To investigate monocyte maturation and CD14 receptor expression during in vitro culture.
Main Methods:
- Monocytes were isolated from LJP patients and controls, stimulated with LPS, and their PGE2 secretion was measured via radioimmunoassay.
- Experiments were conducted on FIM and after 10 days of culture to generate MDM.
- Cell surface expression of CD71 (maturation marker) and CD14 was analyzed using cell-ELISA.
Main Results:
- LPS-stimulated FIM from LJP patients secreted 3-4 times more PGE2 than controls.
- After 10 days in culture, LJP MDM exhibited normalized PGE2 secretion, comparable to control MDM.
- LJP FIM showed significantly lower CD14 expression than controls, which became comparable after in vitro maturation.
Conclusions:
- In vitro culture conditions reverse the hyper-responsiveness of LJP monocytes to LPS, normalizing PGE2 secretion.
- The reduced CD14 expression on LJP monocytes is not directly correlated with their hyper-responsiveness to LPS.