Salivary microbiome variations in type 2 diabetes mellitus patients with different stages of periodontitis

Abstract

Background: To investigate the difference of salivary microbiome composition in type 2 diabetes mellitus with different stages of periodontitis.

Methods: 105 patients diagnosed with T2DM were divided into four groups according to the Stage of periodontitis.The 16 S rDNA hypervariable regions V3-V4 were amplified by polymerase chain reaction (PCR) after saliva DNA was extracted. The library was constructed and Illumina sequencing was performed. The sequencing results were compared with the silva 138 database, and the salivary microbiome of the four groups of patients was studied by species composition analysis, species difference analysis, principal coordinate analysis, and correlation analysis.

Results: There were significant differences in alpha diversity of salivary microbiome among the four groups, but no difference in Beta diversity. At the phylum level, there was one differential bacteria-Firmicutes, while at the genus level, there were 16 differential bacteria. Spearman's correlation analysis identified significant correlations between periodontal health indices (PLI, SBI, AL and PD) and the abundances of over 13 genera, including Streptococcus, Gemella and Capnocytophaga, etc. Additionally, the duration of diabetes exhibited a positive correlation with AL and PD.

Conclusions: There are differences in salivary microbial composition in patients with type 2 diabetes mellitus with different stages of periodontitis. There is a correlation between some saliva microbiota and periodontal inflammation.

Keywords: Correlation analysis; Microbiota; Periodontitis; Saliva; Type 2 diabetes mellitus.

Fig. 1

Venn diagram (A) and rarefaction curve (B) of the Stage1, Stage2, Stage3 and Stage4 groups. The number of overlapping parts in the Venn diagram represents the number of OTUs shared by the four groups, and the number of non-overlapping parts represents the number of OTUs unique to the four groups

Fig. 2

Relative abundance of salivary microbiota at the phylum level (A) and Firmicutes (B) of the Stage1, Stage2, Stage3 and Stage4 groups

Fig. 3

Heatmap of the relative abundances of 50 dominant genera (A) and relative abundances of genera of Streptococcus (B), Porphyromonas (C), Capnocytophaga (D), Peptostreptococous (E), norank_f Lachnospiraceae (F), Lentimicrobium (G), Peptococcus (H), Bifidobacterium (I), Scardovia (J), Pseudopropionibacterium (k), norank_f_norank_o_norank_c_Gracilibacteria (L), unclassified_f Streptococcaceae (M), Parascardovia (N), Alloscardovia (O), Prevotellaceae_UCG-004 (P), Cutibacterium (Q). The Stage1 group is shown in red. The Stage2 group is shown in blue. The Stage3 group is shown in green. The Stage4 group is shown in purple. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 4

Alpha diversity of the saliva microbiome in Stage1, Stage2, Stage3 and Stage4 groups. (A) Sobs index; (B) Shannon index; (C) Simpson index; (D) Ace index; (E) Chao index; (F) Goods_coverage index. *P < 0.05, **P < 0.01

Fig. 5

PCoA plot. The red circle represents the Stage1 group, the blue triangle represents the Stage2 group, the green diamond represents the Stage3 group and the purple cross represents the Stage4 group. Each point represents a sample, and the distance between the points represents the degree of difference

Fig. 6

The heatmap shows Spearman correlation coefficients between the abundance of 50 genera and the periodontal indices in patients with T2DM and periodontitis. The R value is shown in different colors in the figure, red indicates R > 0, blue indicates R < 0. *P < 0.05; **P < 0.01;***P < 0.001