Fig. 2

Oral microbial diversity in SLE was increased. A Rarefaction analysis between the number of samples and the number of OTUs. As the number of samples increased, the number of OTUs approached saturation in SLE (n = 100) and HC (n = 200). Compared with the HC, the number of OTUs in SLE was increased significantly. B As measured by the Shannon index, the oral microbial diversity was significantly increased in SLE (n = 100) versus HC (n = 200) (p < 0.001). C As measured by the Simpson index, the oral microbial diversity was significantly increased in SLE (n = 100) versus HC (n = 200) (p < 0.001). D As estimated by the NMDS analysis, the OTU distribution was significantly different between SLE (n = 100) and HC (n = 200). E As estimated by the PCoA, the OTU distribution was significantly different between SLE (n = 100) and HC (n = 200). F A Venn diagram showed that 709 out of 832 OTUs were shared in both groups, while 70 OTUs were specific to SLE (n = 100). ***, p < 0.001. HC healthy controls, SLE systemic lupus erythematosus, OTU operational taxonomic unit, NMDS nonmetric multidimensional scaling, PCoA, principal coordinate analysis