학회지 리뷰

Fusobacterium nucleatum has been reported to be more abundant in subgingival microbiome of smokers than that of non-smokers. This study investigated in vitro effect of cigarette smoke condensate (CSC) on F. nucleatum subsp. Nucleatum ATCC 25586. Sterile CSC-rich broth (400 ml) was prepared with smoke derived from 40 burning cigarettes (8 mg tar and 0.7 mg nicotine/cigarette). The total growth of F. nucleatum for 24 h decreased in the presence of CSC (6.25–25%). Whereas the relative biofilm formation, auto-aggregation activity, and resistance to erythromycin increased in the presence of CSC. Genome-wide transcriptome analysis revealed that a total of 163 genes were differentially expressed more than 2-fold by CSC. Most of these were functionally related to transport and metabolism of inorganic ion and amino acid, and energy production and conversion. Upregulation of the gene encoding macrolide-efflux protein was also identified. The genes most prominently upregulated by CSC were associated with iron acquisition and use of glutamate and tryptophan, all of which can directly affect the transition of F. nucleatum to a biofilm state. Meanwhile, the genes related to utilization of tyrosine and serine were downregulated. Collectively, CSC induced phenotypic changes of F. nucleatum subsp. nucleatum, such as decreased cell division, transition to a biofilm state and reduced susceptibility to some antibiotics. These phenotypic changes seem to be partly related to altered expression of genes associated with iron utilization and amino acid preference. Our results provide new clues into the role of F. nucleatum in the oral cavity of smokers.