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Modulation of human neutrophil adherence by oral bacteria
W K Seow1, L M Whitman, P S Bird
1Department of Dentistry, University of Queensland.
Abstract:
Polymorphonuclear neutrophils (PMNs) comprise over 90 per cent of leukocytes in the oral cavity. Although these phagocytic cells have primary defence roles in the gingiva, their stimulation by micro-organisms may also cause substantial tissue damage due to the release of lysosomal enzymes and oxygen radicals. Adherence of PMNs to the endothelium and their subsequent diapedesis and egress to areas of infection are considered early vital events in the inflammatory process. In this study, oral bacteria were screened to determine their direct effects on PMN activation using an in vitro method of measuring PMN adherence to Dacron fibres. Most of the bacteria investigated increased PMN adherence, indicating their potential to cause tissue damage through the release of PMN lysosomal enzymes and other products. In contrast, Bacteroides species suppressed PMNs, indicating their ability to circumvent the phagocytic cells, thus gaining a potential advantage in dental colonization. The modulatory effects of oral bacteria on PMN activation may have significant roles in the immunopathogenesis of oral disease.
Insights
Oral bacteria significantly impact polymorphonuclear neutrophils (PMNs), immune cells crucial for oral health. Some bacteria activate PMNs, potentially causing tissue damage, while others, like Bacteroides, suppress them, aiding dental colonization.
Area of Science:
- Immunology
- Microbiology
- Oral Biology
Background:
- Polymorphonuclear neutrophils (PMNs) are key immune cells in the oral cavity, defending against pathogens.
- While essential for defense, PMN activation by microorganisms can lead to tissue damage via lysosomal enzymes and oxygen radicals.
- PMN adherence and diapedesis are critical early steps in oral inflammation.
Purpose of the Study:
- To investigate the direct effects of various oral bacteria on PMN activation.
- To assess the potential of oral bacteria to modulate PMN adherence and function.
- To understand the role of bacterial modulation of PMNs in the immunopathogenesis of oral diseases.
Main Methods:
- Screening of oral bacteria for their direct impact on PMN activation.
- Utilizing an in vitro method to measure PMN adherence to Dacron fibres.
- Quantifying bacterial effects on PMN function.
Main Results:
- Most tested oral bacteria increased PMN adherence, suggesting a role in initiating tissue damage.
- Bacteroides species demonstrated an ability to suppress PMN activity.
- This suppression by Bacteroides may facilitate dental colonization by evading phagocytic defenses.
Conclusions:
- Oral bacteria exhibit diverse modulatory effects on PMN activation.
- Bacterial-induced PMN suppression, as seen with Bacteroides, offers a survival advantage for colonization.
- These interactions are significant in the immunopathogenesis of oral diseases, influencing inflammatory responses and tissue integrity.