Levy, R. B. | bioRxiv Science

bioRxiv2026

The TET-dependent DNA demethylation pathway is the driving force of hematopoiesis

A complex network of signaling cascades regulates the differentiation of hematopoietic stem and progenitor cells (HSPCs) into mature blood cells during hematopoiesis. We demonstrated that DNA demethylation driven by Ten-Eleven Translocation (TET) enzymes controls the activity of multiple of these signaling cascades. This occurs because dozens of genes, essential for the specification (e.g., Gata1, Tcf7, Bcl11b, Pou2af1) and maturation (e.g., TCR and BCR signaling) of erythroblasts, T cells, and B cells, are highly methylated in HSPCs and must be demethylated by TET enzymes to be activated in their respective blood lineages. Many genes required for the maturation, but not for the specification, of monocytes and granulocytes are highly methylated in HSPCs, a condition that does not impede the emergence of these cells but can significantly impair their function. Loss of TET activity leads to severe impairment of hematopoiesis and results in hematological malignancies.

immunology↗

bioRxiv2025

Pretransplant targeting of TNFRSF25 and CD25 stimulates recipient Tregs in target tissues ameliorating GVHD post-HSCT

The current approach to minimize transplant-associated complications, including graft-versus-host disease (GVHD) includes long-term pharmacological immune suppression frequently accompanied by unwanted side effects. Advances in targeted immunotherapies regulating alloantigen responses in the recipient continue to reduce the need for pan-immunosuppression. Here, in vivo targeting of the TNF superfamily receptor 25 (TNFRSF25) and the high affinity IL-2 receptor with a TL1A-Ig fusion protein and low dose IL-2, respectively, was used to pretreat recipient mice prior to allogeneic-HSCT (aHSCT). Pretreatment induced Treg expansion persisting early post-aHSCT leading to diminished GVHD and improved transplant outcomes. Expansion was accompanied by an increase in frequency of stable and functionally active Tregs as evidenced by in vitro assays using cells from major GVHD target tissues including colon, liver, and eye. Importantly, pretreatment supported epithelial cell function/integrity, a diverse microbiome including reduction of pathologic bacteria overgrowth and promotion of butyrate producing bacteria, while maintaining physiologic levels of obligate/facultative anaerobes. Notably, using a sphingosine 1-phosphate receptor agonist to sequester T cells in lymphoid tissues, we found that the increased tissue Treg frequency included resident CD69+CD103+FoxP3+ hepatic Tregs. In contrast to infusion of donor Treg cells, the strategy developed here resulted in the presence of immunosuppressive target tissue environments in the recipient prior to the receipt of donor allo-reactive T cells and successful perseveration of GVL responses. We posit strategies that circumvent the need of producing large numbers of ex-vivo manipulated Tregs, may be accomplished through in vivo recipient Treg expansion, providing translational approaches to improve aHSCT outcomes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/633453v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@10ef7aforg.highwire.dtl.DTLVardef@1a70f03org.highwire.dtl.DTLVardef@caa144org.highwire.dtl.DTLVardef@121b657_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗