Related Experiment Videos
Regulation of plasminogen activator secretion in mouse peritoneal macrophages. II. Inhibition by immunomodulators of
Abstract:
Two classes of immunomodulators of bacterial origin, peptidoglycan derivatives and lipopolysaccharides, are able to block in vitro the production of plasminogen activator by elicited macrophages: the release of the enzyme into the medium is inhibited and the intracellular activity reduced. In the case of peptidoglycan derivatives, high molecular weight compounds like WSA (water-soluble adjuvant) are stronger inhibitors than small molecules like MPP (muramyl pentapeptide). MDP (muramyl dipeptide) gives partial inhibition only. WSA (at 100 micrograms/ml) completely inhibits plasminogen activator production; the inhibition is reversible and specific. LPS is active at low concentrations (25-100 ng/ml). At concentrations higher than 50-100 ng/ml the action of LPS becomes irreversible and less specific. Peptidoglycan-derived immunomodulators can inhibit plasminogen activator production in the presence of polymixin B or in the case of macrophages obtained from C3H/HeJ mice; LPS is inactive under such conditions.
Insights
Bacterial immunomodulators, including peptidoglycan derivatives and lipopolysaccharides, inhibit plasminogen activator production in macrophages. High molecular weight peptidoglycans are more effective inhibitors than lipopolysaccharides.
Area of Science:
- Immunology
- Biochemistry
Background:
- Macrophages play a key role in immune responses.
- Plasminogen activator is an enzyme involved in various physiological and pathological processes.
- Immunomodulators derived from bacteria can influence macrophage activity.
Purpose of the Study:
- To investigate the in vitro effects of bacterial immunomodulators on plasminogen activator production by elicited macrophages.
- To compare the inhibitory potential of peptidoglycan derivatives and lipopolysaccharides on plasminogen activator release and activity.
Main Methods:
- Macrophages were elicited and treated with various bacterial immunomodulators.
- Plasminogen activator production (release into medium and intracellular activity) was measured.
- The effects of different concentrations and molecular weights of immunomodulators were assessed.
- Specificity and reversibility of inhibition were evaluated.
Main Results:
- Both peptidoglycan derivatives and lipopolysaccharides inhibited plasminogen activator production.
- High molecular weight peptidoglycans (e.g., water-soluble adjuvant - WSA) were stronger inhibitors than low molecular weight ones (e.g., muramyl pentapeptide - MPP).
- Muramyl dipeptide (MDP) showed partial inhibition.
- WSA completely inhibited production at 100 µg/ml, reversibly and specifically.
- Lipopolysaccharide (LPS) was effective at low concentrations (25-100 ng/ml) but became irreversible and less specific at higher doses.
- Peptidoglycan derivatives inhibited plasminogen activator production even with polymyxin B or in C3H/HeJ macrophages, where LPS was inactive.
Conclusions:
- Bacterial immunomodulators, particularly high molecular weight peptidoglycan derivatives, effectively inhibit macrophage plasminogen activator production.
- The inhibitory mechanisms and specificity differ between peptidoglycan derivatives and LPS.
- These findings highlight the potential of bacterial-derived compounds in modulating immune responses via plasminogen activator inhibition.