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Activity of polymorphonuclear leukocytes in the presence of sulfide
R Claesson1, M Granlund-Edstedt, S Persson
1Department of Oral Microbiology, University of Umeå, Sweden.
Abstract:
Polymorphonuclear leukocytes (PMN) isolated from human blood were exposed to various levels of hydrogen sulfide. The effect on respiratory burst, myeloperoxidase activity, and capacity to phagocytose and kill bacteria were studied. A 1-h exposure of the PMN to 1 mM sulfide did not decrease their myeloperoxidase activity or their capacity to initiate a respiratory burst. Actually the products of the respiratory burst rapidly oxidized sulfide. The phagocytosis and killing of bacteria in the presence of 1 mM sulfide was only decreased to a minor extent. Myeloperoxidase in cell extract was, however, almost completely inhibited by 1 microM sulfide. These results indicate that hydrogen sulfide does not easily permeate PMN. PMN may be able to function in infected sites with high sulfide levels such as in the gingival pockets of periodontal disease. In the oxygenated areas of these sites the PMN may actually help in the detoxification of sulfide.
Insights
Hydrogen sulfide (H2S) at 1 mM did not impair polymorphonuclear leukocytes (PMN) function, suggesting PMNs can operate in infected sites with high H2S levels, aiding in its detoxification.
Area of Science:
- Immunology
- Biochemistry
- Microbiology
Background:
- Polymorphonuclear leukocytes (PMNs) are crucial immune cells involved in fighting bacterial infections.
- Hydrogen sulfide (H2S) is a gas produced endogenously and by bacteria, with complex roles in inflammation.
- Periodontal disease sites can exhibit elevated H2S levels, posing a challenge for PMN function.
Purpose of the Study:
- To investigate the impact of hydrogen sulfide exposure on human PMN functions.
- To determine if PMNs can maintain antimicrobial activity in the presence of H2S.
- To assess the potential role of PMNs in H2S detoxification at infection sites.
Main Methods:
- Isolation of human PMNs from blood.
- Exposure of PMNs to varying concentrations of hydrogen sulfide (H2S).
- Assay of respiratory burst activity, myeloperoxidase (MPO) activity, and bacterial phagocytosis/killing capacity.
Main Results:
- 1-hour exposure to 1 mM H2S did not significantly reduce PMN myeloperoxidase activity or respiratory burst initiation.
- The respiratory burst products rapidly oxidized H2S.
- Phagocytosis and bacterial killing by PMNs were only slightly decreased in the presence of 1 mM H2S.
- Myeloperoxidase activity in cell extracts was strongly inhibited by 1 µM H2S, indicating limited H2S penetration into PMNs.
Conclusions:
- Hydrogen sulfide does not easily permeate human PMNs.
- PMNs retain significant antimicrobial function even at high H2S concentrations.
- PMNs may be functional in H2S-rich environments like periodontal pockets.
- PMNs could contribute to H2S detoxification in oxygenated areas of infected sites.