Comment on: ‘Metagenome-wide association study of gut microbiome revealed novel aetiology of rheumatoid arthritis in the Japanese population’ by Kishikawaet al

Response to: ‘Comment on ‘Metagenome-wide association study of gut microbiome revealed novel aetiology of rheumatoid arthritis in the Japanese population’ by Kishikawaet al.’ by Kitamuraet al

“…We thank Kitamura et al for their interest in our study and for providing their thoughts through correspondence 1. They reported interesting characteristics of Porphyromonas gingivalis ( Pg ) regarding rheumatoid arthritis (RA) as follows: (1) oral infection of Pg increased serum levels of lipopolysaccharide (LPS)2 3; (2) oral administration o f Pg decreased the proportion of phylum Bacteroidetes 3; and (3) serum LPS levels were inversely associated with Bacteroides counts.…”

“…Another concern by Kitamura et al was the distinct distributions of the RA prognostic factors between the RA case groups with high and low abundance in the Prevotella spp or Pg . They reported that serum LPS-binding protein was positively correlated with activity indices and biomarkers of RA (e.g., Disease Activity Score 28-joint count C reactive protein (DAS28CRP), CRP, rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA)) 1. We assessed whether the relative abundance of the Prevotella spp and Pg showed the correlation with RF, ACPA, DAS28-CRP and the Steinbrocker stage.…”