Effect of Porphyromonas gingivalis and Fusobacterium nucleatum on FABP4 Expression

Objectives: we observed whether the periodontal pathogens, P.gingivalis and F. nucleatum, affect FABP4 expression in macrophages and further investigated the mechanism that modulates FABP4. Through this study, we intend to gain knowledge on the correlation between periodontitis and systemic diseases in a mechanistic way.
Methods: Raw264.7 were grown in 75-cm2 flasks in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% heat -inactivated fetal bovine serum (FBS). Cells were maintained at 37°C in a 5% CO2 humidified incubator. Fusobacterium nucleatum polymorphum and Porphyromonas gingivalis strain 381 were maintained in GAM broth containing 5 mg/mL hemin and 5 μg/mL vitamin K in an anaerobic chamber at 37°C. P. gingivalis and F. nucleatum were suspended in reduced transport fluid (RTF)and 4% sterile carboxymethylcellulose (CMC) for oral administration. Six-weekold-female C57BL/6 mice from KOATECH (Korea) were maintained in groups and housed in cages.
Results: P. gingivalis and F. nucleatum induce morphological changes and increase FABP4 expression in Raw264.7 macrophages.
FABP4 expression by periodontal pathogens is dependent on both Mitogen Activated Protein (MAP) kinase and PI3K/Akt pathways.
Mice administered with F. nucleatum showed increased FABP4 expression.
Mice administered with P. gingivalis or F. nucleatum exhibited higher levels of glucose and serum insulin levels compared with the control group
Conclusions: Our results show that the levels of FABP4 were more elevated in the serum of mice administered F.nucleatum than in non-infected or P. gingivalis-infected mice. Additionally, the insulin levels were higher in mice administered F. nucleatum than in non-infected or P. gingivalis infected mice. These findings suggest that F. nucleatum may play a role in insulin resistance.