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Adherence of Mycoplasma pneumoniae to human alveolar macrophages
A Athamna1, M R Kramer, I Kahane
1Department of Membrane and Ultrastructure Research, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
Abstract:
The human pathogen Mycoplasma pneumoniac causes primary atypical-cold agglutinin-positive pneumonia. Since alveolar macrophages internalize mycoplasma as part of their immune defense, we studied characteristics of the human macrophage receptor for opsonized and nonopsonized M. pneumoniae. The glass-adhering subpopulation of M. pneumoniae attached more than the non-adherent subpopulation. The attachment was dose-dependent and enhanced by opsonization in the presence of human serum. It is inhibited by sulfated compounds such as dextran-sulfate and polyanetholsulfonic acid, but not by dextran or several monosaccharides, suggesting that sulfated glycolipids on the macrophage surface may act as receptors for M. pneumoniae binding. In addition, sialylated compounds, such as fetuin and alpha 1-acid glycoprotein, were found to be potent inhibitors of the attachment, also indicating the role of sialic acid residue in recognition and attachment of M. pneumoniae to human alveolar macrophages.
Insights
Mycoplasma pneumoniae attachment to human immune cells involves specific receptors. Sulfated compounds and sialic acid residues on macrophages are key to this interaction, influencing pneumonia development.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Mycoplasma pneumoniae is a human pathogen causing pneumonia.
- Alveolar macrophages are crucial immune cells that internalize M. pneumoniae.
- Understanding macrophage receptors for M. pneumoniae is vital for immune defense mechanisms.
Purpose of the Study:
- To characterize the human macrophage receptor involved in M. pneumoniae binding.
- To investigate the role of opsonization in M. pneumoniae attachment.
- To identify specific molecular components on macrophages that mediate M. pneumoniae recognition.
Main Methods:
- Studied attachment of M. pneumoniae subpopulations to human macrophages.
- Investigated dose-dependency and serum opsonization effects on attachment.
- Assessed inhibition of attachment by various sulfated and sialylated compounds.
Main Results:
- Glass-adhering M. pneumoniae showed higher attachment rates.
- Attachment was dose-dependent and enhanced by human serum opsonization.
- Sulfated compounds (dextran-sulfate, polyanetholsulfonic acid) and sialylated compounds (fetuin, alpha 1-acid glycoprotein) potently inhibited attachment.
Conclusions:
- Sulfated glycolipids on macrophage surfaces may act as receptors for M. pneumoniae.
- Sialic acid residues on macrophages play a significant role in M. pneumoniae recognition and attachment.
- These findings elucidate key molecular interactions in M. pneumoniae pathogenesis and host defense.