Figure 4. Acute GVHD blocks stromal reorganization and repair of the FRC network.

(A) Heatmap depicting relative expression values of specific genes involved in a stromal reorganization program. Relative expression is shown in FRCs isolated from untransplanted mice, or from TCDBM recipients and TCDBM+T recipients 7 days following F→M BMT. (B) Absolute numbers of host and donor LTi cells were evaluated at indicated time points in the presence or absence of acute GVHD following F→M BMT. Dotted line indicates mean absolute numbers of LTi cells in untreated mice. Statistical analysis is of donor cells only. Data derived from 3 independent experiments. (C) Surface expression of VCAM1 and ICAM1 on CD45^–CD31^–gp38⁺ LN stromal cells in untransplanted controls (gray) and BMT recipients of TCDBM alone (blue) or TCDBM+T (red) at indicated time points after F→M BMT. Summary data depicting MFI of VCAM1 within the CD45^–CD31^–gp38⁺ population in TCDBM or TCDBM+T recipients is shown below the respective flow cytometry plots (data derived from 6 independent experiments). (D) [Rorc WT→Rorc WT] or [Rorc KO→Rorc WT] chimeras were analyzed for the presence of LTi cells within LNs at 8 weeks after primary BMT. Plots depict expression of CD127 and RORγt among lineage^–CD117⁺ cells. Percentage and absolute numbers of FRCs is shown for [Rorc WT→Rorc WT] and [Rorc KO→Rorc WT] chimeras at 8 weeks after primary BMT (data derived from 3 independent experiments). (E) Eight weeks after the first BMT, [Rorc WT→Rorc WT] and [Rorc KO→Rorc WT] chimeras were reirradiated and underwent secondary F→M BMT with either TCDBM alone or TCDBM+T to induce acute GVHD. Plots show percentage (left) and absolute numbers (right) of FRCs analyzed at 2 weeks after the second transplantation (data derived from 2 independent experiments). Data represent mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001 by Mann-Whitney U test (B and C) or Kruskal-Wallis ANOVA (E).