Abstract:Aim: To explore the mechanism of interkingdom interactions among endodontic infection causing microbes (C. albicans and E. faecalis) that trigger pathogenesis of the disease and cause ecological shifts within root canal.
Methodology: Biofilms of two endodontically relevant microorganisms from different kingdoms were selected and grown at 8 hours and 24 hours to make mature dual species biofilms. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to assess the expression of key virulence genes in both microorganisms. Next, RNA sequencing was performed on whole C. albicans cells to identify differentially expressed genes and pathways in response to the presence of E. faecalis. Finally, nanodiamonds and small molecules from FDA-approved drug library were evaluated to target virulence mechanisms and compare the behaviour of the dual-species biofilm with that of single-species biofilms.
Results: E. faecalis downregulated key virulence genes in C. albicans, while C. albicans upregulated genes that are associated with E. faecalis adhesion and biofilm formation. Moreover, the presence of E. faecalis significantly altered the transcriptome of C. albicans. The most significantly upregulated pathways in C. albicans included stress responses, oxidoreductase activity, amino acid biosynthesis, and fungal biofilm matrix p>0.05. Genes involved in glucose sensation and transportation, glycerol biosynthesis process, and arginine catabolic pathways were significantly downregulated P<0.05. The coexistence of both microorganisms in dual-species biofilms also resulted in increased tolerance to nanodiamonds and small molecules from FDA approved drugs. Conclusion: As evidenced by transcriptomic results the interkingdom interaction caused an ecological shift that affected virulence of both microorganisms. Moreover, the findings provide important insights into the potential for repurposing drugs and nanomaterials as broad antimicrobial agents, which could be effective against biofilms formed by these microorganisms.