Community Development between Porphyromonas gingivalis and Candida albicans Mediated by InlJ and Als3

Area of Science:

• Microbiology
• Oral Health
• Infectious Diseases

Background:

• Candida albicans is a significant opportunistic pathogen, particularly in immunocompromised individuals.
• In the oral cavity, C. albicans forms polymicrobial communities, where interactions can promote virulence factors like hyphal and biofilm formation.
• C. albicans colonization is more frequent in the subgingival area, correlating with increased incidence of periodontal disease.

Purpose of the Study:

• To investigate the specific interactions between the fungal pathogen Candida albicans and the bacterial periodontal pathogen Porphyromonas gingivalis.
• To elucidate the molecular mechanisms underlying the coadhesion and community development between these two species.
• To understand the impact of these interspecies interactions on the gene expression and potential virulence of P. gingivalis.

Main Methods:

• Assessing coadhesion of C. albicans and P. gingivalis in planktonic and sessile states.
• Utilizing protein deletion mutants (InlJ in P. gingivalis, Als3 in C. albicans) to study adhesion mechanisms.
• Employing recombinant proteins to confirm binding interactions.
• Performing transcriptional profiling using RNA sequencing (RNA-Seq) to analyze gene expression changes in co-cultures.

Main Results:

• C. albicans and P. gingivalis were found to coadhere in both planktonic and sessile phases.
• The internalin-family protein InlJ in P. gingivalis was crucial for adhesion to C. albicans, and recombinant InlJ inhibited this binding.
• Als3, a major hyphal protein in C. albicans, was involved in binding to P. gingivalis, with InlJ interacting with Als3.
• RNA-Seq revealed 57 uniquely upregulated genes in P. gingivalis in a manner dependent on InlJ, including those related to growth and division.
• C. albicans induced the upregulation of the type IX secretion apparatus in P. gingivalis.

Conclusions:

• InlJ-Als3-dependent binding is a key mechanism facilitating interdomain community development between C. albicans and P. gingivalis.
• The interaction enhances the potential virulence of P. gingivalis within these polymicrobial communities.
• These findings provide critical insights into interdomain microbial interactions that can exacerbate diseases like periodontal disease.