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[Adherence of E. coli strains with various adhesins to macrophages from bone marrow and the cell line P 388D1]
Abstract:
The adherence of E. coli with different hemagglutination patterns to mouse-bone-marrow-derived macrophages and macrophages of the cell line P 388D1 was investigated. The bacterial strains used showed different adherence to macrophages or red blood cells. MS-adhesins identified by hemagglutination tests were also involved in the attachment of bacteria to macrophages. In addition, strains containing both, MS and MR adhesins, simultaneously showed a participation of their MR-adhesins in adherence to macrophages. This could be shown by inhibition experiments with alpha-D-mannose. Bacteria of strain D 133 failed to induce hemagglutination of any source of erythrocytes tested, though MR-adherence to macrophages could be found. In contrast, other strains known to carry MR-hemagglutinins on their cell surface, did not attach to macrophages, even if much higher numbers of bacteria were used. A linear correlation between the amount of bacteria used and the number of adherent bacteria/macrophage was detectable. The number of bacteria found on the macrophages differed according to the population of macrophages studied, indicating differences in the expression of corresponding receptors in the macrophage plasma membrane. In order to investigate the role of fimbriae in adherence, bacteria were used which had been grown under fimbriae suppressing conditions. Some of the bacterial strains showed a 10 to 30 fold reduction in adherence to macrophages upon this treatment, indicating the importance of fimbriae-associated adhesins in the interaction of bacteria and phagocytes. On the other hand, three bacterial strains could be identified, whose adherences was not influenced by such culture conditions. This means that beside fimbrial adhesins even membrane bound adhesins could be involved in the phagocytic process.
Insights
Escherichia coli (E. coli) adherence to macrophages varies based on adhesins, with fimbriae playing a key role. Different macrophage populations also influence bacterial attachment, highlighting diverse interaction mechanisms.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Escherichia coli (E. coli) exhibits diverse hemagglutination patterns.
- Macrophage adherence by bacteria is crucial for host-pathogen interactions.
- Adhesins mediate bacterial attachment to host cells.
Purpose of the Study:
- To investigate the adherence patterns of E. coli strains to macrophages.
- To determine the role of specific adhesins (MS and MR) and fimbriae in bacterial attachment.
- To explore differences in macrophage receptor expression affecting bacterial adherence.
Main Methods:
- Hemagglutination assays to identify bacterial adhesins.
- Co-incubation of E. coli strains with mouse-bone-marrow-derived macrophages and P 388D1 cell line.
- Inhibition experiments using alpha-D-mannose.
- Culturing bacteria under fimbriae-suppressing conditions.
Main Results:
- MS-adhesins are involved in E. coli attachment to macrophages.
- MR-adhesins contribute to adherence in strains possessing both MS and MR adhesins.
- Fimbriae-associated adhesins significantly influence bacterial adherence, though some strains utilize membrane-bound adhesins independently.
Conclusions:
- Bacterial adhesin type and fimbrial expression critically affect E. coli adherence to macrophages.
- Macrophage receptor expression varies, influencing bacterial attachment efficiency.
- Both fimbrial and non-fimbrial adhesins play roles in E. coli-macrophage interactions.