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Interaction of Haemophilus influenzae with the mammalian extracellular matrix
R Virkola1, K Lähteenmäki, T Eberhard
1Department of Biosciences, University of Helsinki, Finland.
Abstract:
The adhesiveness of 2 unencapsulated nonfimbriated strains of Haemophilus influenzae, 23459 and 23330, and the encapsulated fimbriated strain 770235 to extracellular matrix (ECM) and to its isolated components was studied, as was the potential of H. influenzae plasminogen receptors to enhance degradation of ECM and bacterial penetration through basement membrane. All strains exhibited efficient adhesiveness to reconstituted basement membrane and to ECM from cultured human endothelial cells. Strains 23459 and 23330 efficiently adhered to immobilized laminin, fibronectin, and various collagens. Strain 770235 adhered efficiently to fibronectin and type I and III collagens and with low efficiency to laminin. With all 3 strains, plasmin generated on H. influenzae plasminogen receptors degraded laminin and fibronectin as well as ECM from human endothelial cells. Plasmin bound on H. influenzae cells also potentiated penetration of bacteria through a basement membrane preparation reconstituted on membrane filters. These results give evidence for a role of ECM adherence and plasminogen activation in the spread of H. influenzae through tissue barriers.
Insights
Haemophilus influenzae uses extracellular matrix (ECM) adherence and plasminogen activation to degrade tissue barriers. This mechanism facilitates bacterial spread and tissue invasion, highlighting potential therapeutic targets.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Haemophilus influenzae is a significant human pathogen.
- Bacterial invasion of host tissues is crucial for pathogenesis.
- Extracellular matrix (ECM) components play vital roles in tissue structure and cell adhesion.
Purpose of the Study:
- To investigate the adherence of Haemophilus influenzae strains to ECM components.
- To determine the role of bacterial plasminogen receptors in ECM degradation.
- To assess the impact of ECM adherence and plasminogen activation on bacterial penetration through basement membranes.
Main Methods:
- Studied adhesiveness of encapsulated and unencapsulated H. influenzae strains to ECM and isolated components.
- Utilized reconstituted basement membrane and ECM from cultured human endothelial cells.
- Investigated plasmin generation on bacterial plasminogen receptors and its effect on ECM degradation and basement membrane penetration.
Main Results:
- All H. influenzae strains showed efficient adherence to basement membrane and endothelial cell ECM.
- Specific adherence patterns were observed for different bacterial strains to laminin, fibronectin, and collagens.
- Plasmin generated on bacterial receptors degraded ECM components and enhanced bacterial penetration through basement membranes.
Conclusions:
- ECM adherence is a key factor in H. influenzae pathogenesis.
- Plasminogen activation by H. influenzae contributes to ECM degradation and tissue invasion.
- These findings suggest ECM interactions and plasminogen activation are critical for H. influenzae spread through tissue barriers.