TNF and Cowden disease: gnavus comprises at least two clades, one of which is enriched in CD patients and produces inflammatory polysaccharides, which induce the production of TNF-α by dendritic cells via TLR4.28,29 Although the immunostimulatory effects of R. gnavus 131A1 isolated herein were weak, R. gnavus may facilitate the colonization of other bacteria associated with CD pathogenesis.