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Role of platelet-activating-factor (PAF) on cellular responses after stimulation with leptospire lipopolysaccharide
1Department of Preventive Dentistry, Health Sciences University of Hokkaido, Japan.
Abstract:
Leptospire lipopolysaccharide (LPS) stimulated the adherence of polymorphonuclear neutrophils (PMNs) to human umbilical vein endothelial cells (HUVEC). Enhanced PMN adherence in response to leptospire LPS can be mediated by platelet-activator-factor (PAF), because a PAF antagonist reduced adherence. Leptospire LPS also induced the adherence platelets or U937. The second experiment involved leptospire LPS elicited platelet aggregation in a PMN-platelet mixture, because leptospire LPS stimulated human PMN but not the human platelets. The platelet response was observed only in the mixture system and was inhibited by a PAF antagonist. PAF could be an important pathogenic factor in human leptospirosis.
Insights
Leptospire lipopolysaccharide (LPS) increases neutrophil adherence to endothelial cells, potentially via platelet-activating factor (PAF). This LPS also triggers platelet aggregation in a mixed cell environment, suggesting PAF
Area of Science:
- Immunology
- Microbiology
- Pathology
Background:
- Leptospire lipopolysaccharide (LPS) is a key component of pathogenic Leptospira bacteria.
- Leptospirosis is a significant global zoonotic disease with diverse clinical manifestations.
- The interaction between bacterial components and host immune cells is crucial in disease pathogenesis.
Purpose of the Study:
- To investigate the role of Leptospire LPS in modulating host cell interactions.
- To determine the involvement of platelet-activating factor (PAF) in LPS-induced cellular responses.
- To explore the effect of Leptospire LPS on platelet aggregation in the context of immune cell presence.
Main Methods:
- Human umbilical vein endothelial cells (HUVEC) and polymorphonuclear neutrophils (PMNs) were used in adherence assays.
- Leptospire LPS was applied to cell cultures to assess its effects on PMN-HUVEC adherence.
- Platelet aggregation assays were performed using PMN-platelet mixtures, with and without a PAF antagonist.
Main Results:
- Leptospire LPS significantly enhanced the adherence of PMNs to HUVECs.
- The addition of a PAF antagonist partially reduced LPS-induced PMN adherence, indicating PAF mediation.
- Leptospire LPS induced platelet aggregation specifically in a PMN-platelet mixture, an effect inhibited by a PAF antagonist.
Conclusions:
- Leptospire LPS plays a role in promoting inflammatory responses by increasing neutrophil adherence.
- Platelet-activating factor (PAF) is implicated as a mediator in LPS-induced PMN adherence and platelet aggregation.
- These findings suggest that PAF may be a critical pathogenic factor in human leptospirosis.