Although A33+ Li-EVs and A33+ Li-EVs of IBD mice (IBD-A33+ Li-EVs) had similar size distributions (Supplementary Table 1), IBD-A33+ Li-EVs contained more TGF-β1 as measured by western blot analysis, and showed a stronger inhibitory effect on CD4+ T-cell proliferation in vitro than did A33+ Li-EVs (Fig. 3a,b). This evidence concerns the gene TGFB1 and inflammatory bowel disease.