SLC9A3 and colitis: Our study and those in NHE3-/- mice found a significant expansion in Proteobacteria (Engevik et al., 2013; Larmonier et al., 2013), which is consistent with our previous report that ~50% of NHE3IEC-KO mice develop mild to moderate colitis three weeks after induction of intestinal NHE3 deletion (Xue et al., 2020).