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Mechanisms of attachment of Mycoplasma arthritidis to host cells in vitro
L R Washburn1, S Hirsch, L L Voelker
1Department of Microbiology, University of South Dakota School of Medicine, Vermillion 57069.
Abstract:
Although other investigators have reported that Mycoplasma arthritidis failed to attach to several types of mammalian cells in vitro, we showed that it attached well to rat synovial fibroblasts, lung cells, and skin cells but not to kidney cells, suggesting that receptor sites are unequally expressed or distributed among different rat tissues. M. arthritidis also attached poorly to canine kidney and to baby hamster kidney cells, although it did attach to human fetal lung and fetal amnion cells. Four M. arthritidis strains, two virulent and two avirulent, all attached equally well to rat lung cells. Attachment was inhibited by trypsinization, suggesting that the major adhesins are protein. Fab' fractions of rabbit antisera against four M. arthritidis strains partially inhibited adherence of both homologous and heterologous strains, although not to the same extent, indicating some degree of antigenic heterogeneity among their adhesins. A filter-cloned variant of M. arthritidis 158p10p9, designated LC1, attached poorly compared with the parent strain. Missing from this variant were two proteins migrating within the 81- to 90-kDa range by polyacrylamide gel electrophoresis; in their place was a 24-kDa antigen that may be a truncated version of one of these proteins. A monoclonal antibody that partially inhibited attachment recognized all these peptides by Western immunoblotting. An additional attachment-inhibiting monoclonal antibody recognized a 71-kDa antigen present in both low-adherence and fully adherent populations. The low-adherence variant LC1 induced slightly but significantly less arthritis in Lewis rats than did a fully adherent clone.
Insights
Mycoplasma arthritidis attachment varies by cell type and host. Protein adhesins mediate this binding, with variations influencing disease severity.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Mycoplasma arthritidis adherence to host cells is crucial for pathogenesis but poorly understood.
- Previous studies showed inconsistent in vitro attachment of M. arthritidis to mammalian cells.
Purpose of the Study:
- To investigate the cell tropism and adherence mechanisms of Mycoplasma arthritidis.
- To identify the specific proteins involved in M. arthritidis attachment.
Main Methods:
- In vitro adherence assays using various mammalian cell lines (rat, canine, hamster, human).
- Treatment of M. arthritidis with trypsin to assess protein involvement in adherence.
- Immunological studies using antisera and monoclonal antibodies to identify adhesins.
- Analysis of a low-adherence variant using polyacrylamide gel electrophoresis and Western immunoblotting.
Main Results:
- M. arthritidis demonstrated differential attachment to rat tissues, binding well to synovial fibroblasts, lung, and skin cells, but not kidney cells.
- Attachment was inhibited by trypsin, indicating protein adhesins are key.
- Antisera and monoclonal antibodies identified specific M. arthritidis adhesins in the 81-90 kDa and 71 kDa ranges.
- A low-adherence variant showed reduced virulence in a rat arthritis model.
Conclusions:
- Mycoplasma arthritidis exhibits specific adherence patterns to host cells, influenced by tissue-specific receptor expression.
- Proteinaceous adhesins, including those in the 81-90 kDa and 71 kDa ranges, are critical for M. arthritidis attachment.
- Adherence efficiency correlates with the capacity of M. arthritidis to induce arthritis.