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Possible role for a polysaccharide antigen shared between Streptococcus pyogenes and S. mutans in the pathogenesis of
Abstract:
Streptococcus mutans has been shown to share a polysaccharide (PS) antigen with S. pyogenes strains isolated from patients with acute poststreptococcal glomerulonephritis (PSGN), using a monoclonal antibody f-77 reactive with the PS. To investigate the pathogenetic role of the shared PS in PSNG, experimental nephritis was induced in animals. Rats were immunized thrice with heat-killed cells of S. mutans or S. pyogenes, followed by an intravenous injection of live cells of S. pyogenes. Histologic examination showed that both animal groups had comparable degrees of diffuse proliferative nephritis characterized by immune deposits. The shared PS antigen was detected in glomeruli of all nephritic rats by immunofluorescence using monoclonal antibody f-77. Furthermore, all nephritic rats had an elevated antibody titer to the shared PS antigen. These results suggest that prior sensitization (infections such as dental caries) to S. mutans modulates immune responses to subsequent S. pyogenes infections and induces immune-complex disease (PSGN) through the shared PS antigen.
Insights
Prior Streptococcus mutans infection may trigger post-streptococcal glomerulonephritis (PSGN) in susceptible individuals. A shared antigen between S. mutans and S. pyogenes appears to play a key role in this immune-complex disease.
Area of Science:
- Immunology
- Microbiology
- Nephrology
Background:
- Streptococcus mutans shares a polysaccharide (PS) antigen with Streptococcus pyogenes strains.
- This shared antigen is implicated in acute post-streptococcal glomerulonephritis (PSGN).
Purpose of the Study:
- To investigate the pathogenetic role of the shared PS antigen in PSGN.
- To determine if prior sensitization to S. mutans influences immune responses to S. pyogenes.
Main Methods:
- Experimental nephritis was induced in rats by immunizing with heat-killed S. mutans or S. pyogenes, followed by live S. pyogenes.
- Histological examination and immunofluorescence using monoclonal antibody f-77 were performed.
- Antibody titers to the shared PS antigen were measured.
Main Results:
- Both immunization groups developed diffuse proliferative nephritis with immune deposits.
- The shared PS antigen was detected in the glomeruli of all nephritic rats.
- Nephritic rats exhibited elevated antibody titers to the shared PS antigen.
Conclusions:
- Prior sensitization to S. mutans can modulate immune responses to subsequent S. pyogenes infections.
- The shared PS antigen appears to be a critical factor in inducing immune-complex disease (PSGN).