Salivary features of periodontitis and gingivitis in type 2 diabetes mellitus

Abstract

Type 2 diabetes mellitus (T2DM) is associated with cellular abnormalities, tissue and organ dysfunctions, and periodontitis. This investigation examined the relationship between the oral microbiome and salivary biomarkers in T2DM patients with or without periodontitis. This cohort (35-80 years) included systemically healthy non-periodontitis (NP; n = 31), T2DM without periodontitis (DWoP; n = 32) and T2DM with periodontitis (DWP; n = 29). The oral microbiome [Operational Taxonomic Units (OTUs)] (16 s rRNA sequencing) and targeted host salivary biomarkers (immunoassays) were assessed. We identified 47 OTUs that were significantly different in abundance between NP samples and any disease subset or between disease subgroups. The most unique microbiome patterns were observed in the DWP group. Differences in genera/species abundance were also observed when T2DM patients were stratified by extent of periodontal inflammation and disease (i.e., generalized versus localized gingivitis/periodontitis). Salivary biomarkers showed significant elevations in MMP-8, MMP-9, resistin, IL-1β, IL-6, IFNα, and BAFF (THFSR13b) comparing generalized to localized periodontitis. Salivary analytes showed significant positive correlations with specific microbiome members, predominantly in DWP patients. Odds ratio analyses reinforced that a panel of biologic markers (IL-6, MMP-8) and bacteria (e.g., Bacteroidetes, Fusobacteria, Spirochaetes) discriminated the severity and extent of periodontal disease in this diabetic population.

Keywords: Diabetes; Inflammation; Microbiome; Periodontitis; Saliva.

Fig. 1

Clinical features of patient groups (NP—non-periodontitis; DWoP—T2DM without periodontitis; DWP—T2DM with periodontitis). The DWoP group had localized (LG) or generalized (GG) gingivitis. The DWP group had localized (LP) or generalized (GP) periodontitis. The bars are the group means and the vertical brackets enclose 1 SEM. The connecting horizontal bars identify significant differences between the groups and the asterisk (*) for BMI values denotes significantly different than the NP group at p < 0.05 as determined by an ANOVA.

Fig. 2

Relative abundance of different phyla to total sequence readouts in individual (A) NP, (B) DWoP, or (C) DWP subjects identified as generalized or localized disease.

Fig. 2

Relative abundance of different phyla to total sequence readouts in individual (A) NP, (B) DWoP, or (C) DWP subjects identified as generalized or localized disease.

Fig. 3

Relative abundance of OTUs (eg. species, genera) in to total sequence readouts of NP, DWoP (GG, LG), and DWP (GP, LP) in salivary microbiome samples. Panels A, B and C organize the microbes based upon general relative abundance across the samples. Bars denote group means with asterisk (*) signifying a significant difference between NP and disease groups, and hashtag (#) identifying one or more disease subsets that differs in OTU (eg. species, genera) abundance from the other groups. OTUs were only included if a significant difference at p < 0.01 was detected for any comparison as determined by ANOVA.

Fig. 4

Levels of salivary analytes in subsets of DWoP and DWP T2DM patients with localized (LG, LP) or generalized (GG, GP) disease compared to control subjects (NP). Bars denote group means and vertical brackets signify 1 SEM. Significance is indicated compared to the NP group, as well as between the various disease strata as determined by ANOVA.

Fig. 5

Frequency of OTUs with significant correlations with levels of the individual salivary analytes. (A) Bars denote the number of positive or negative correlations for each analyte within the groups. (B) Frequency of significant correlations across the 11 salivary analytes with the individual OTUs. Each dot represents the number of significant (p < 0.05) correlations for a specific subject group. Only OTUs were included where there was any significant correlation in one or more patient groups.

Fig. 6

Display of Odd Ratios (OR) for various microbes (TOP panel) and host factors (BOTTOM panel) comparing (A) localized gingivitis (LG) to localized periodontitis (LP) and generalized gingivitis (GG) to generalized periodontitis (GP), and (B) LG to GG and LP to GP in the T2DM groups. Each point denotes an OR value for the specific variable (microbe, host factor). Positive OR denotes elevated level in generalized disease compared to localized disease or in gingivitis vs. periodontitis. A negative OR denotes elevated level in LG, LP, or gingivitis compared to generalized disease or periodontitis, respectively.