LAUSR

OBJECTIVE To invest the saliva microbiome in patients with immunoglobulin G4-related disease (IgG4RD) compared with primary Sjögren's syndrome (SS). METHODS Saliva samples were collected from 11 IgG4RD and 11 SS patients who visited IMSUT Hospital, The Institute of Medical Science, the University of Tokyo. DNA was extracted from the samples, and primers were used to amplify the V3-V4 region of bacterial and archaeal 16S rRNA, which was then analyzed by paired-end sequencing. Amplicon reads were processed using QIIME2 to generate representative sequences. The Greengenes database was used to identify the bacterial flora in each sample and compare them between groups. RESULTS The IgG4RD and SS groups exhibited differences in bacterial diversity. Cluster analyses of attributed classification groups by species and disease showed that IgG4RD and SS cases formed individual clusters. Significant differences in relative abundance between IgG4RD and SS were observed for the following organisms: Mogibacterium (p=0.0051), Solobacterium moorei (p=0.0195), Slackia (p=0.0356), and Moryella (p=0.0455). CONCLUSION Salivary microbiome analysis of IgG4RD and SS patients revealed significantly higher relative proportions of Mogibacterium, Solobacterium moorei, Slackia, and, Moryella bacteria in IgG4RD compared with SS.