Biology of Blood and Marrow Transplantation The Intestinal Stem Cell Compartment is the Initial Target of T Cell Invasion in GI Gvhd  Ya-Yuan Fu, Anastasiya Egorova, Catherine Sobieski, Marco Calafiore, Hans Clevers, Alan M. Hanash  Biology of Blood and Marrow Transplantation  Volume 24, Issue 3, (March 2018) DOI: 10.1016/j.bbmt.2017.12.638 Copyright © 2017 Terms and Conditions

Figure 1 B6→BALB/c BMT indicates preferential T cell invasion of the lower crypt region in the small intestine and GFP* donor T cells direct contact with ISC compartment at the crypt base 4 days post-BMT. (A) Imaged intestinal tissue was divided into villus and crypt regions and stained with antic-CD3 (red) to indentify T cell localization within 3-D architecture of gut. (B) Representative 3-D images show T cell infiltration of the lower crypt region after T cell replete BMT; scale bars, 100 µm. (C) Quantification of donor T cell density; ***P < .001. Right panel shows GFP* T cells adjacent to a crypt base lacking ISCs, serosal surface view from the bottom of the crypt base (red, lysozyme; green, GFP; blue, nuclei); scale bars, 25 µm. Biology of Blood and Marrow Transplantation 2018 24, DOI: (10.1016/j.bbmt.2017.12.638) Copyright © 2017 Terms and Conditions

Figure 2 MAdCAM-1* vasculature clusters around the crypt compartment. (A) 3-D imaging of small intestine vasculature with MAdCAM-1 vessels (red) and MAdCAM-1 staining (light blue) demonstrates greater vascular density in the villus region (above the dash line) compared to the crypt region (below the dash line), but MAdCAM-1 vasculature was predominantly localized arount the crypt compartment; scale bars, 150 µm. (B) Quantification of MAdCAM-1 density; **P < .01;. ***P < .001. Biology of Blood and Marrow Transplantation 2018 24, DOI: (10.1016/j.bbmt.2017.12.638) Copyright © 2017 Terms and Conditions

Figure 3 Treatment with anti-MAdCAM-1 reduced crypt region invasion by donor T cells, resulting in ISC protection. (A) Quanfication of donor T cell densities indicate the reduction of donor T cells infiltration in the lower crypt region with anti-MAdCAM-1 treatment; **P < .01. (B) Representative nuclear images of crypt base columnar ISCs (light blue) and Paneth cells (dark blue) in 3-D after treatment with isotype antibody or anti-MAdCAM-1; scale bars, 25 µm. Biology of Blood and Marrow Transplantation 2018 24, DOI: (10.1016/j.bbmt.2017.12.638) Copyright © 2017 Terms and Conditions