[A preliminary study on the effect of histatin 5 inhibiting Porphyromonas gingivalis and Fusobacterium nucleatum co-aggregation].

Objective: To detect the inhibitory ability of histatin 5 on the auto-aggregation of Porphyromonas gingivalis (Pg), and the co-aggregation of Pg with Fusobacterium nucleatum (Fn); and to provide a theoretical basis for the role of oral innate immunity played in the inhibition of chronic periodontitis. Methods: Saliva and supragingival, subgingival plaque samples were collected from 49 chronic periodontitis patients in School of Stomatology, China Medical University and 27 periodontal healthy individuals. Enzyme linked immunosorbent assay was used to assess the amount of histatin 5 in saliva, absolute quantitative real-time PCR (qPCR) was applied to detect the DNA copies of Fn, Pg and total bacteria in supragingival and subgingival plaque samples. The effects of histatin 5 on auto- and co-aggregation were assessed by bacterial adhesion test and scanning electron microscopy. Hemagglutinin gene, arginine-gingipains gene in Pg and FomA gene in Fn were tested by relative qPCR. Independent samples t-test was used to calculate the significance between the experimental group and the control group. P-value<0.05 was considered statistically significant. Results: For chronic periodontitis patients, there was an inverse correlation between the concentration of histatin 5 and Fn and Pg in supragingival plaque samples (r=-0.379, r=-0.624). Similarly, an inverse correlation was also observed between the concentration of histatin 5 and subgingival Fn and Pg, respectively (r=-0.404, r=-0.314). As for periodontally healthy individuals, there was an inverse correlation between the concentration of histatin 5 and supragingival and subgingival Pg (r=-0.572, r=-0.533). Bacterial adhesion test and scanning electron microscopy certified that 25 mg/L histatin 5 inhibited the auto-aggregation of Pg-Pg and the co-aggregation of Pg-Fn. Results of qPCR showed that 25 mg/L histatin 5 up-regulated hemagglutinin gene by (14.52±3.25) fold and down-regulated FomA gene to (0.22±0.10) fold. Conclusions: Histatin 5 could inhibit the auto-aggregation of Pg-Pg and the co-aggregation of Pg-Fn by regulating hemagglutinin gene and FomA gene expression.