Associations of Salivary BPIFA1 Protein in Chronic Periodontitis Patients with Type 2 Diabetes Mellitus

Abstract

Aims: To explore the differences in salivary BPI fold containing family A, member 1 (BPIFA1) concentration among type 2 diabetes mellitus (T2DM) subjects with various severities of chronic periodontitis and to determine whether BPIFA1 in saliva can be used as a potential biomarker of T2DM.

Methods: Unstimulated saliva samples were collected from 44 subjects with T2DM and 44 without T2DM (NDM). Additionally, demographic data and general health parameters, including fasting blood glucose (FBG) and body mass index (BMI), were collected. We also detected full-mouth clinical periodontal parameters including probing pocket depth (PPD), clinical attachment level (CAL), bleeding index (BI), and plaque index (PLI). Salivary BPIFA1, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) concentrations were also detected.

Results: BPIFA1 in saliva was detected at relatively high levels. T2DM subjects had decreased salivary BPIFA1 concentrations (P = 0.031). In T2DM subjects with nonperiodontitis or severe periodontitis, the level of BPIFA1 was significantly lower compared with that of NDM. Salivary TNF-α concentration displayed a similar trend to BPIFA1 in the NDM group.

Conclusions: BPIFA1 protein is rich in saliva and might be used as a potential predictive biomarker of T2DM, especially in patients with severe periodontitis and nonperiodontitis. This trial is registered with ChiCTR-ROC-17010310.

Figure 1

A histogram showing the concentrations of salivary BPIFA1, TNF-α, and IL-6 (pg/mL, median (IQR)) in NDM and T2DM subjects. The blue stripes represent NDM subjects, the red stripes represent T2DM subjects, and the purple stripes represent all subjects. Each group is presented by median (stripes) and interquartile range (bars). Salivary BPIFA1 concentration was significantly higher in the NDM group than in the T2DM group. The significant differences are indicated by an asterisk (^∗P = 0.031). No significant difference in TNF-α or IL-6 concentration was observed between T2DM and NDM groups.

Figure 2

Line graph including salivary BPIFA1, TNF-α, and IL-6 (pg/mL, median (IQR)) concentrations in different severities of periodontitis stratified by T2DM. Blue lines and dots represent NDM subjects, and the red lines and dots represent T2DM subjects. Each group included 4 grades of periodontitis by severity including none, mild, moderate, and severe, and the median values are displayed (dots). The concentration of BPIFA1 (a) in the nonperiodontitis group was significantly higher than in the moderate periodontitis group. The level of BPIFA1 in the moderate periodontitis group was significantly lower than in the severe periodontitis group. The concentration of BPIFA1 was at its lowest in the moderate periodontitis group. However, in those with T2DM, the concentration of BPIFA1 (b) was significantly lower in the nonperiodontitis group in comparison to both the mild periodontitis and moderate periodontitis groups. BPIFA1 in the severe periodontitis group was significantly lower than in the mild and moderate periodontitis groups. Comparisons between the T2DM and NDM groups revealed that in T2DM subjects without periodontitis, BPIFA1 levels were significantly lower in those NDM subjects without periodontitis and was significantly lower in T2DM subjects with severe periodontitis individuals compared with NDM subjects with severe periodontitis. The concentration of TNF-α is shown in (c) and (d). In NDM subjects, the concentration of TNF-α in the nonperiodontitis group was significantly higher than in the mild periodontitis group and moderate periodontitis groups. BPIFA1 was significantly lower in the moderate periodontitis group compared with the severe periodontitis group. However, in those subjects with T2DM, the concentration of TNF-α was significantly lower in the severe periodontitis group in comparison to the moderate periodontitis group. Comparisons between T2DM and NDM groups revealed that T2DM subjects with moderate periodontitis had significantly lower BPIFA1 than NDM subjects. The concentration of IL-6 among the NDM and T2DM groups is presented in (e) and (f), which showed that the concentration of IL-6 in the moderate periodontitis group was significantly higher than in the severe periodontitis group, among T2DM subjects.

Figure 3

Curve correlation between the concentration of BPIFA1 (pg/mL) and periodontal parameters among individuals with or without T2DM. Blue lines and dots represent NDM subjects, and red lines and dots represent T2DM subjects. Equations and correlation coefficients are shown. As shown in (a), in NDM subjects, PLI and the concentration of salivary BPIFA1 had a statistically significant relationship in the form of a quadratic term. In T2DM subjects (b), CAL and the concentration of salivary BPIFA1 had a statistically significant relationship in the form of a quadratic term.