ARG1 and inflammatory bowel disease: Ly6g, a neutrophil-expressed maturation marker [38, 39] was significantly increased by DNBS in CR mice, but only showed trends towards increases in ABX and GF mice (Fig. 3H), while the activated neutrophil marker Arginase (Arg1), the release of which is associated with T-cell dysfunction (which is implicated in the development of inflammation in IBD [40, 41], was massively upregulated in CR and ABX mice in response to DNBS (though only significantly in the latter), with relatively no effect in GF mice (Fig. 3I).