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Serum antibody response to Bacteroides fragilis in experimental sinusitis
K M Westrin1, P Stierna, A Weintraub
1Dept. of Otorhinolaryngology, Karolinska Institute, Huddinge University Hospital, Sweden.
Abstract:
Maxillary sinusitis was induced in New Zealand white rabbits by local inoculation of 10(6) colony-forming units of Bacteroides fragilis NCTC 9343, and the serum IgG, IgA and IgM antibody responses to cell wall antigens were studied. Prior to inoculation, and one, two, three and four weeks after induction, serum samples were obtained and analysed for antibodies to the lipopolysaccharide and the capsular polysaccharide. Capsular polysaccharide from B. fragilis ATCC 23745 was used as control. The rise in IgG activity against NCTC 9343 capsular polysaccharide and lipopolysaccharide was most marked and sustained throughout the four weeks. The increases in IgA concentration were moderate and sometimes transient, and a more pronounced IgA increase was seen with IFA than with EIA. The IgM peak levels were weak and usually declined within two to three weeks. The development of antibody to the lipopolysaccharide was similar to that of the NCTC 9343 capsular polysaccharide antibodies, though somewhat delayed in time. No significant increase in antibody to the control capsular polysaccharide was seen.
Insights
This study investigated the immune response to Bacteroides fragilis in rabbits with maxillary sinusitis. Rabbits showed a strong and sustained IgG antibody response to bacterial cell wall antigens, indicating a significant immune reaction.
Area of Science:
- Immunology
- Microbiology
- Otolaryngology
Background:
- Maxillary sinusitis is a common condition often associated with bacterial infections.
- Bacteroides fragilis is a Gram-negative anaerobic bacterium implicated in various infections, including sinusitis.
- Understanding the host immune response to specific bacterial components is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the serum antibody responses (IgG, IgA, IgM) to cell wall antigens of Bacteroides fragilis in a rabbit model of maxillary sinusitis.
- To analyze the temporal dynamics of these antibody responses over a four-week period post-induction.
- To differentiate the immune response to specific antigens like lipopolysaccharide and capsular polysaccharide.
Main Methods:
- Maxillary sinusitis was induced in New Zealand white rabbits via local inoculation of Bacteroides fragilis NCTC 9343.
- Serum samples were collected at baseline and at one, two, three, and four weeks post-induction.
- Antibody levels against lipopolysaccharide and capsular polysaccharide of B. fragilis were measured using immunoassay techniques (IFA and EIA).
Main Results:
- A marked and sustained increase in IgG antibody levels against both capsular polysaccharide and lipopolysaccharide of B. fragilis was observed throughout the four weeks.
- Moderate and sometimes transient increases in IgA were detected, with a more pronounced response noted with indirect fluorescent antibody (IFA) compared to enzyme immunoassay (EIA).
- IgM antibody levels peaked weakly and generally declined within two to three weeks; no significant antibody response was seen against a control capsular polysaccharide.
Conclusions:
- Rabbits infected with Bacteroides fragilis mount a robust and persistent IgG antibody response to key cell wall antigens, suggesting their importance in the host defense against this pathogen.
- The observed antibody profiles indicate distinct kinetics for IgG, IgA, and IgM responses, with IgG being the most dominant and long-lasting.
- These findings contribute to understanding the immunopathogenesis of Bacteroides fragilis-associated maxillary sinusitis and highlight potential targets for immunomodulatory therapies.