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Pioneer oral streptococci produce immunoglobulin A1 protease
M F Cole1, M Evans, S Fitzsimmons
1Department of Microbiology, Georgetown University Medical Center, Washington, D.C. 20007.
Insights
Pioneer viridans streptococci in neonates produce immunoglobulin A1 (IgA1) protease, aiding survival. Some strains modify IgA1 susceptibility, potentially enhancing colonization in the infant oral cavity.
Area of Science:
- Microbiology
- Immunology
- Oral Health
Background:
- Viridans streptococci are early colonizers of the infant oral cavity.
- The secretory immune system, particularly immunoglobulin A1 (IgA1), plays a role in host defense against oral bacteria.
- Understanding bacterial enzymes that interact with IgA1 is crucial for deciphering colonization dynamics.
Purpose of the Study:
- To investigate the production of IgA1 protease and glycosidases by pioneer viridans streptococci in neonates.
- To determine the prevalence of IgA1 protease activity among different streptococcal species.
- To explore how streptococcal enzymes and host IgA1 interact and influence bacterial survival.
Main Methods:
- Collection of 367 viridans streptococci isolates from 40 neonates within the first month postpartum.
- Testing isolates for the production of immunoglobulin A1 (IgA1) protease and glycosidases.
- Analysis of IgA1 cleavage patterns and susceptibility to enzymatic degradation.
Main Results:
- Fifty percent of streptococcal isolates produced IgA1 protease, with high prevalence in Streptococcus oralis and Streptococcus sanguis.
- Three distinct IgA1 heavy chain cleavage patterns were observed.
- Some IgA1 protease-negative isolates modified IgA1, rendering it resistant to cleavage by other streptococcal IgA1 proteases.
Conclusions:
- Certain pioneer streptococci possess IgA1 protease, contributing to their survival in the oral cavity.
- The ability of some strains to alter IgA1 susceptibility may be a mechanism for immune evasion.
- These enzymatic activities are significant factors in the early colonization of the infant oral microbiome.
Abstract:
As part of a longitudinal study of the relationship between bacterial colonization and the secretory immune response, 367 isolates of pioneer viridans streptococci collected from 40 breast- and bottle-fed neonates within the first month postpartum were tested for the production of immunoglobulin A1 (IgA1) protease and glycosidases. Fifty percent of the streptococci isolated produced IgA1 protease, including all isolates of Streptococcus oralis and S. sanguis, 60.7% of S. mitis biovar 1 isolates, and some isolates that could not be identified. Three cleavage patterns of alpha 1 heavy chains were observed. Six isolates of S. mitis biovar 1 that did not produce IgA1 protease attacked the alpha 1 chain. Incubation of IgA1 protease-negative S. mitis biovar 1 isolates with IgA1, either prior to or together with S. sanguis, rendered the IgA1 paraprotein resistant to cleavage by the IgA1 protease of S. sanguis. The ability of some pioneer streptococci in the human oral cavity to produce IgA1 protease and of others to modify the susceptibility of IgA1 to cleavage by IgA1 protease perhaps enhances their ability to survive in this habitat.