Colonization with ubiquitous protist Blastocystis ST1 ameliorates DSS-induced colitis and promotes beneficial microbiota and immune outcomes

Abstract

<jats:title>Abstract</jats:title><jats:p><jats:italic>Blastocystis</jats:italic> is a species complex that exhibits extensive genetic diversity, evidenced by its classification into several genetically distinct subtypes (ST). Although several studies have shown the relationships between a specific subtype and gut microbiota, there is no study to show the effect of the ubiquitous <jats:italic>Blastocystis</jats:italic> ST1 on the gut microbiota and host health. Here, we show that <jats:italic>Blastocystis</jats:italic> ST1 colonization increased the proportion of beneficial bacteria <jats:italic>Alloprevotella</jats:italic> and <jats:italic>Akkermansia</jats:italic>, and induced Th2 and Treg cell responses in normal healthy mice. ST1-colonized mice showed decreases in the severity of DSS-induced colitis when compared to non-colonized mice. Furthermore, mice transplanted with ST1-altered gut microbiota were refractory to dextran sulfate sodium (DSS)-induced colitis via induction of Treg cells and elevated short-chain fat acid (SCFA) production. Our results suggest that colonization with <jats:italic>Blastocystis</jats:italic> ST1, one of the most common subtypes in humans, exerts beneficial effects on host health through modulating the gut microbiota and adaptive immune responses.</jats:p>