Lachnospiraceae have indeed been associated with the production of SCFAs,34 35 which in turn have been linked to the induction of Foxp3+ Treg cells.35–38 Therefore, further assessment of SCFAs from faecal samples of our IBD and PSC-IBD cohort and mouse models of sclerosing cholangitis is required to test whether the enrichment in Lachnospiraceae is indeed associated with increased SCFA levels and subsequently increased Foxp3+ Treg-cell numbers. Here, FOXP3 is linked to sclerosing cholangitis.