Targeting Donor XCR1+ and CD11b+ Dendritic Cells Prevents Th1 and Th17-dependent GVHD Within the Gastrointestinal Tract
Researchers at the Fred Hutchinson Cancer Center have found specific donor dendritic cell subsets are dominant drivers of gastrointestinal acute GVHD that can be therapeutically targeted to prevent lethal disease. In this study, published in Blood, they demonstrate that donor XCR1⁺ conventional dendritic cells are the key alloantigen-presenting population that promotes Th1 differentiation and gut-homing programming, whereas donor CD11b⁺ conventional dendritic cells support a separate Th17-dependent pathogenic axis. The authors conclude that gut GVHD is not driven uniformly by “dendritic cells” as a whole, and that selectively interrupting XCR1⁺ and CD11b⁺ donor cDC pathways can blunt Th1- and Th17-mediated intestinal GVHD.
Acute GI GVHD remains a major cause of early mortality after allogeneic BMT and is fundamentally dependent on MHC-II–restricted alloantigen presentation to donor CD4 T cells. Previously, the authors established that recipient APC initiate GVHD, but donor APC amplify and sustain it, making donor APC an attractive therapeutic target. The authors therefore performed high-resolution tissue mapping of donor DC subsets in gut compartments and draining mesenteric lymph nodes (mLN) during GVHD, then used subset-specific depletion tools to establish causality. They leveraged Xcr1-DTR mice to deplete donor XCR1⁺CD103⁺CD11b⁻ cDC and Clec4c-DTR mice to deplete donor plasmacytoid DC, and used a TEa TCR-transgenic system in which CD4 T-cell activation depends on donor APC presenting a defined alloantigen in isolation. In parallel, the authors also tested a pharmacologic strategy, WIN18,446, a pan-ALDH1A inhibitor that blocks retinoic acid biosynthesis, to assess whether dendritic cell functional pathways could be therapeutically modulated rather than genetically deleted.
Donor SiglecH⁺ pDC were prominent in the ileal epithelium of non-GVHD controls but were largely absent during GVHD and were YAe-negative, consistent with minimal alloantigen presentation. In contrast, donor CD103⁺CD11b⁻ (XCR1⁺) cDC showed marked enrichment in the mLN during GVHD and were strongly YAe⁺, identifying them as the dominant alloantigen-presenting subset. Functionally, depleting donor XCR1⁺ cDC, but not donor pDC, significantly reduced GVHD lethality in models where donor APC-mediated priming is isolated, and reduced T cells physically proximate to XCR1⁺ cDC in mLN compared with pDC. XCR1⁺ cDC depletion decreased alloantigen-specific CD4 T-cell expansion in the GI tract and mLN, reduced IFN-γ–producing TEa cells, and lowered gut-homing integrin α4β7 expression and α4β7⁺ TEa numbers. Pharmacologically, WIN18,446 improved survival and unexpectedly acted primarily by suppressing CD11b⁺ cDC expansion (rather than XCR1⁺ cDC), reducing alloantigen-specific Th17 differentiation; these effects were abolished when donor bone marrow lacked ALDH1A1, supporting an ALDH1A1-dependent mechanism. Together, these data establish two mechanistically distinct donor cDC pathways, XCR1⁺ cDC driving Th1 and gut imprinting and CD11b⁺ cDC driving Th17, and suggest that selectively targeting these donor APC axes could prevent lethal intestinal GVHD while avoiding broader immune ablation.
Reference:
Takahashi S, Inoue T, Ensbey KS, et al. Targeting donor XCR1+ and CD11b+ dendritic cells prevents Th1 and Th17-dependent GVHD within the Gastrointestinal Tract. Blood. Published online February 9, 2026.