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Preferential adsorption of human neutrophil myeloperoxidase isoform III by oral bacteria
1Section of Oral Biology, UCLA School of Dentistry 90024-1668.
Abstract:
Neutrophil myeloperoxidase (MPO) adsorbs to bacteria as a pre-requisite for killing by the MPO/hydrogen-peroxide/chloride system. Three chromatographically distinct isoforms of MPO (MPO I, MPO II, and MPO III) have been isolated from human neutrophils. The purpose of this study was to determine whether oral bacteria--including Actinobacillus actinomycetemcomitans, Capnocytophaga sputigena, Haemophilus aphrophilus, and Eikenella corrodens--differentially adsorb the three major isoforms of MPO from a mixture of MPO I, II, and III, and to assess the effect of pH and normal human serum (NHS) on MPO adsorption. MPO III adsorbed preferentially (i) at high bacterial concentrations, (ii) in the pH range of 6.0-8.0, and (iii) in the presence and absence of NHS. These results support the role of MPO III in the killing of oral bacteria.
Insights
Neutrophil myeloperoxidase isoform III preferentially adsorbs to oral bacteria. This finding supports the role of myeloperoxidase (MPO) III in the MPO/hydrogen-peroxide/chloride system for bacterial killing.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Neutrophil myeloperoxidase (MPO) is crucial for bacterial killing via the MPO/hydrogen-peroxide/chloride system.
- Three distinct MPO isoforms (MPO I, II, and III) have been isolated from human neutrophils.
Purpose of the Study:
- To investigate differential adsorption of MPO isoforms by oral bacteria.
- To assess the influence of pH and normal human serum (NHS) on MPO adsorption.
Main Methods:
- Isolation of three MPO isoforms from human neutrophils.
- Incubation of MPO isoforms with a mixture of oral bacteria (A. actinomycetemcomitans, C. sputigena, H. aphrophilus, E. corrodens).
- Analysis of MPO isoform adsorption under varying pH and NHS conditions.
Main Results:
- MPO III demonstrated preferential adsorption to oral bacteria.
- Optimal adsorption of MPO III occurred at high bacterial concentrations and pH range of 6.0-8.0.
- NHS presence or absence did not significantly alter MPO III adsorption patterns.
Conclusions:
- MPO III plays a significant role in the interaction with and killing of oral bacteria.
- The findings highlight the specific contribution of MPO III in the innate immune response against oral pathogens.