Immunogenicity of Mycobacterium avium subsp. paratuberculosis proteins in Crohn's disease patients
Horacio Bach1, Hin Hin Ko, Eran A Raizman
1Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia, Canada. horacio.bach@gmail.com
Unlabelled:
The association between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) is supported by several studies reporting the detection or isolation of MAP from human tissues, but a direct association is still debatable.
Objective:
To evaluate the survival of MAP in human intestinal cells and to measure the presence of antibodies against two mycobacterial proteins necessary for the survival of the bacterium in the sera of CD patients.
Material And Methods:
Human-derived intestinal cells were infected with three isolates of MAP and the survival of the microorganism was determined. The presence of antibodies against protein tyrosine phosphatase A (PtpA) and protein kinase G (two proteins secreted within the host in the early stages of the invasion) in the sera of CD patients was evaluated. Sera of 20 CD patients and 20 controls were collected and the presence of the antibodies was assayed using enzyme-linked immunosorbent assay (ELISA). Secretion of the PtpA in vivo was visualized by immunostaining.
Results:
MAP survived in intestinal cells, and immunostaining of PtpA showed that the protein was secreted within these cells. Wilcoxon rank sum test revealed that CD patient sera had significantly higher titer of antibodies specific for both of these antigens compared to controls. ELISA results for either protein were not statistically different between men and women.
Conclusions:
The presence of specific antibodies against mycobacterial proteins essential for establishing an infection in the host suggests that MAP can potentially be active in CD patients, and a serological test can be developed for early detection of MAP in CD patients.
Insights
Mycobacterium avium subsp. paratuberculosis (MAP) survives in human intestinal cells, and Crohn
Area of Science:
- Gastroenterology
- Microbiology
- Immunology
Background:
- The link between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) remains debated despite MAP detection in human tissues.
- Investigating MAP's interaction with host cells and immune responses is crucial for understanding CD pathogenesis.
Purpose of the Study:
- To assess MAP survival within human intestinal cells.
- To quantify antibodies against key MAP proteins (PtpA, PrgB) in Crohn's disease patients' sera.
- To explore the potential for a serological diagnostic test for MAP in CD.
Main Methods:
- Human intestinal cells infected with MAP isolates to determine bacterial survival.
- Enzyme-linked immunosorbent assay (ELISA) used to measure antibodies against MAP's PtpA and PrgB proteins in sera from 20 CD patients and 20 controls.
- Immunostaining to visualize PtpA secretion in host cells.
Main Results:
- MAP demonstrated survival within human intestinal cells.
- Significant elevation of antibodies against PtpA and PrgB was observed in CD patients compared to controls.
- PtpA was confirmed to be secreted within intestinal cells.
Conclusions:
- The presence of specific antibodies suggests active MAP infection in CD patients.
- MAP's ability to survive in intestinal cells supports its role in Crohn's disease.
- A serological test targeting these MAP antigens could aid in early CD detection.
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