TRIM21 and systemic lupus erythematosus: The identified taxa, including those with interactions with the SLE-risk HLA alleles, include those that contribute to pathways that are implicated to tonically suppress inflammation (inclusive of the production of butyrate25,26 and indole-3-propionic acid).27 van der Meulen et al. studied a cohort of patients who met criteria for primary SS and SLE with anti-SSA/Ro positivity of 90% and 38%, respectively.28 They report lower bacterial richness, lower Firmicutes/Bacteroidetes ratio and higher relative abundance of Bacteroides species in fecal samples compared with population controls.