IRGM and colitis: DSS treated Irgm1-/- mice did have a reduced number of macrophages, but unlike the WT response to C. rodentium, the number of macrophages in WT mice did not increase during DSS colitis, suggesting that the cause for macrophage decline in Irgm1-/- mice in DSS colitis was distinct from mechanisms underpinning failure to expand macrophages for C. rodentium immunity.